Phylogenetic Relationships among Indigenous and Introduced
Bamboo Species and Genetic Diversity Study of Ethiopian Lowland
Bamboo [Oxytenanthera abyssinica (A. Rich.) Munro] Using cpDNA
Genes ( matK , ndhF and rps16 ) and ISSR Markers
Oumer Abdie Oumer
Addis Ababa University
Addis Ababa Ethiopia
July, 2020
Phylogenetic Relationships among Indigenous and Introduced
Bamboo Species and Genetic Diversity Study of Ethiopian Lowland
Bamboo [Oxytenanthera abyssinica (A. Rich.) Munro] Using cpDNA
Genes ( matK , ndhF and rps16 ) and ISSR Markers
Oumer Abdie Oumer
A Dissertation Submitted to Department of Microbial, Cellular and Molecular Biology in Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Biology (Applied Genetics)
Addis Ababa University
Addis Ababa Ethiopia
July, 2020
DECLARATION
I declare that this Dissertation entitled “Phylogenetic Relationships among Indigenous and
Introduced Bamboo Species and Genetic Diversity Study of Ethiopian Lowland Bamboo
[Oxytenanthera abyssinica (A. Rich.) Munro] Using cpDNA Genes ( matK , ndhF and rps16 )
and ISSR Markers” submitted for the Degree of Doctor of Philosophy (PhD) in Biology
(Applied Genetics) to the School of Graduate Studies, Addis Ababa University, is my original
work and its composition has never been submitted elsewhere for any other award. All sources
of materials used for the Dissertation have been duly acknowledged.
Name: Oumer Abdie
Signature: .
Date: 20- July-2020 .
i
ACKNOWLEDGMENT .( ْٱﻟ َﺤ ْﻤﺪ ُ ِ ﱠ ِ َ ﺭ ِّ ﺏ ْٱﻟ َٰﻌ َﻠ ِﻤ َﻴﻦ ) First and for most, I would like to thank the Almighty I am highly indebted to express my deepest and genuine appreciation and thanks to my supervisors: the late Dr. Kifle Dagne, Dr. Tileye Feyissa and Dr. Kassahun Tesfaye for their excellent guiding, follow-up and support. Without the encouragement and guidance, the completion of this work on this form may not have been possible. Next, I would also like to owe my special thanks to Pakistani supervisor Dr. Muhammad Zeeshan Hyder from Biochemistry, Molecular Biology and Biotechnology (BMBB) Lab., Department of Biosciences, faculty of Sciences, COMSATS University Islamabad (CUI), Islamabad, Pakistan, for inviting me to BMBB laboratory as a Visiting PhD Scholar via The World Academy of Science - COMSATS University Islamabad (the then COMSATS Institute of Information Technology) (TWAS-CIIT) scholarships and for his advice on phylogenetics study.
I extend my deepest acknowledgments to different institutions that have provided financial support: Department of Microbial, Cellular and Molecular Biology (MCMB) of Addis Ababa University (AAU), Assosa University (ASU), TWAS-CIIT scholarships, training the next generation of scientists provided by Carnegie Cooperation of New York (CCNY) through the Regional Universities Forum for Capacity Building in Agriculture (RUFORUM), International Network for Bamboo and Rattan (INBAR) head quarter and East Africa Regional Office. I am thankful to Ethiopian Biodiversity Institute (EBI) for providing bamboo seeds and export permit and Central Ethiopia Environment and Forest Research Center (CE-EFRC) for providing cars to collect samples from Ormoia, Gambella and South nations nationalities and peoples (SNNPs) region for this study.
I am also grateful to former Department Head of MCMB Dr. Gurja B., stream supervisor Dr. Dereje B., current Department Head Dr. Adey F., former Department Head of BMBB Dr. Teyab J. and all department staff members of MCMB for their retireless support and advice.
Dr. Solange U., the former manager for Partnerships and Business Management (PBM) at RUFORUM and currently deputy director general in charge of Animal Resources Research ii and Technology Transfer at Rwanda Agriculture and Animal Resources Development Board (RAB), Jayaraman D., project manager INBAR global programme East Africa Regional Office, Ernest N. A., project manager Inter Africa Bamboo Development Programme INBAR West Africa Regional Office, Dr. Abeje E., former CE-EFRC director and Dagnew Y., former program leader for non-timber forest products at CE-EFRC must be duly acknowledged for their contribution to get research funds.
I would like to thank also my colleagues Dr. Mohammed A., Dr. Fekadu G., Mr. Muluken B., Ms. Hawi N. Mr. Asmamaw A., Mr. Amare E., and Pakistani friends Sana B. A., M. Shoiab and M. Shafiq as well as many more others for their friendly advice and support.
Last but not least, my family (beloved mother Medina Zekat, brothers and sisters) deserves special thanks for their all sided support. My wife Hawa Alkadir, my son M. Amin and daughter Haniyah for their patience, encouragement and giving hope at all times of this study period.
Oumer Abdie
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TABLE OF CONTENTS DECLARATION...... i ACKNOWLEDGMENT ...... ii TABLE OF CONTENTS ...... iv LIST OF TABLES ...... viii LIST OF FIGURES ...... ix LIST OF APPENDICES ...... xii LIST OF ABBREVIATIONS ...... xiii ABSTRACT ...... xiv CHAPTER ONE ...... 1 1. General Introduction ...... 1 1.1. Background ...... 1 1.2. Statement of the problem ...... 4 1.3. Hypothesis ...... 7 1.4. Objectives ...... 8 1.4.1. General Objective ...... 8 1.4.2. Specific objectives ...... 8 CHAPTER TWO ...... 9 2. Literature Review ...... 9 2.1. Taxonomy of Bamboo ...... 9 2.2. Bamboo Cytogenetics, Ploidy Level and Genome Size ...... 10 2.3. Area Coverage and Geographical Distribution of Bamboo ...... 12 2.3.1. Bamboo Distribution in Africa, Ethiopia and Pakistan ...... 13 2.4. Assessment of Phylogenetics and Genetic Diversity Study ...... 15 2.4.1. Chloroplast Genes Based Phylogenetics and Genetic Diversity Study ...... 18 2.4.2. ISSR Based Phylogenetics, Genetic Diversity and Population Structure Study ..22 2.5. Phylogenetic Tree Construction Methods ...... 23 CHAPTER THREE ...... 25 3. Phylogenetic Relationships among the Indigenous and Introduced Bamboo Species using cpDNA Genes Sequences ...... 25 3.1. Materials and Methods ...... 25 iv
3.1.1. Plant Materials and Sample Collections ...... 25 3.1.2. DNA Extraction and Primer Screening ...... 25 3.1.3. PCR Product Profiling, Sequencing and Alignment ...... 26 3.1.4. Phylogenetics Analyses ...... 27 3.2. Results ...... 29 3.2.1. Chloroplast DNA Sequence Character and Sequence Divergence ...... 29 3.2.1.1. GC and AC content analysis ...... 29 3.2.2. Phylogenetic Inference and Relationship...... 31 3.2.2.1. Maximum Parsimony Method Phylogenetics Tree Construction ...... 31 3.2.2.2. Maximum Likelihood Method Phylogenetics Tree Construction ...... 32 3.2.2.3. Neighbor-Joining Method Phylogenetics Tree Construction ...... 33 3.3. Discussion ...... 39 CHAPTER FOUR ...... 42 4. Genetic Diversity, Population Structure and Gene Flow Analysis of Ethiopian Lowland Bamboo [Bambusinea: Oxytenanthera abyssinica (A. Rich.) Munro] Using cpDNA Genes Sequences ...... 42 4.1. Materials and Methods ...... 42 4.1.1. DNA Extraction and PCR amplification...... 44 4.1.2. PCR product profiling, sequencing, and alignment ...... 44 4.1.3. Evolutionary tree construction and network analysis ...... 45 4.1.4. Measuring nucleotide diversity, InDel polymorphism, and gene low and genetic differentiation ...... 46 4.2. Results ...... 47 4.2.1. Chloroplast DNA sequence character and sequence divergence ...... 48 4.2.2. Phylogenetic inference and relationship ...... 49 4.2.2.1. Maximum parsimony method evolutionary history analysis ...... 49 4.2.2.2. Neighbor-Joining method evolutionary history analysis ...... 49 4.2.3. Network Analysis...... 51 4.2.4. Nucleotide Diversity Analysis ...... 53 4.2.5. InDel Polymorphism Analysis ...... 54 4.2.6. Analysis of DNA Divergence ...... 55 v
4.2.7. Gene Flow and Genetic Differentiation ...... 58 4.3. Discussion ...... 59 CHAPTER FIVE ...... 64 5. Genetic Relationship among Indigenous and Introduced Bamboo Species and ISSR Markers Efficiency Analysis ...... 64 5.1. Materials and Methods ...... 64 5.1.1. Plant Material Collection and Sampling Strategy ...... 64 5.1.2. DNA Extraction and Primer Screening ...... 64 5.1.3. ISSR-PCR Amplification and Gel Electrophoresis ...... 66 5.1.4. Scoring and Data Analysis ...... 67 5.2. Results ...... 70 5.2.1. ISSR Marker Banding Patterns ...... 70 5.2.2. Level of polymorphism in ISSR primers ...... 71 5.2.2.1. ISSR primers on genetic polymorphism ...... 71 5.2.2.2. Calculating Markers Efficiency ...... 73 5.2.2.3. Band Pattern and Heterozygosity ...... 74 5.2.3. Nei’s Genetic Distance and Similarity ...... 76 5.2.4. Cluster Analysis ...... 76 5.2.5. Principal Coordinate (PCoA) Analysis ...... 80 5.3. Discussion ...... 83 CHAPTER SIX ...... 86 6. Genetic Diversity and Population Structure Analysis of Ethiopian Lowland Bamboo [Bambusinea: Oxytenanthera abyssinica (A. Rich.) Munro] Using ISSR Marker ...... 86 6.1. Materials and Methods ...... 86 6.1.1. Plant Material Collection and Sampling Strategy ...... 86 6.1.2. DNA Extraction and Primer Screening ...... 86 6.1.3. ISSR-PCR Amplification and Gel Electrophoresis ...... 88 6.1.4. Scoring and Data Analysis ...... 89 6.2. Results ...... 93 6.2.1. ISSR Marker Banding Patterns ...... 93 6.2.2. Level of Polymorphism of Ethiopian Lowland Bamboo ...... 95 vi
6.2.2.1. ISSR Primers on Genetic Polymorphism of Ethiopian Lowland Bamboo ....95 6.2.2.2. Calculating Markers Efficiency ...... 97 6.2.2.3. Band Pattern and Heterozygosity ...... 98 6.2.3. Genetic Polymorphism and Shanon’s Information Index ...... 100 6.2.4. Analysis of Molecular Variance ...... 103 6.2.5. Cluster Analysis ...... 104 6.2.6. Principal Coordinate (PCoA) Analysis ...... 108 6.2.7. Admixture Analysis ...... 109 6.3. Discussion ...... 111 6.3.1. ISSR Markers for the Genetic Polymorphism in Ethiopian Lowland Bamboo ( O. abyssinica ) Populations ...... 111 6.3.2. Genetic Differentiation and Population Structure...... 114 6.3.3. Levels of Genetic Diversity among and Within Populations...... 116 6.3.4. Patterns of relationship and admixture analysis...... 119 7. Conclusion and Recommendation ...... 121 7.1. Conclusion ...... 121 7.2. Recommendation ...... 122 8. References ...... 126 9. APPENDICES ...... 142
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LIST OF TABLES Table 3-1: cpDNA primer sequences, their approximate amplified size and PCR profile. ... 26 Table 3-2: GC and AT content of each and aggregate cpDNA genes...... 30 Table 3-3: List of bamboo species and an accurate and complete GenBank record and/or accession numbers at NCBI ...... 38 Table 4-1: Samples information along with their GPS location ...... 42 Table 4-2: An accurate and complete GenBank record (accession numbers at NCBI)...... 47 Table 4-3: GC and AT content of each and aggregate cpDNA genes...... 48 Table 4-4: Nucleotide diversity analysis on Ethiopian lowland bamboo populations in different Zones...... 53 Table 4-5: InDel polymorphism of Ethiopian lowland bamboo ( O. abyssinica )...... 54 Table 4-6: Effects of gene flow and genetic differentiation on Ethiopian lowland bamboo. 58 Table 5-1: ISSR primers used for PCR amplification...... 65 Table 5-2: Polymorphism of the fifteen ISSR primers on the phylogenetics study ...... 72 Table 5-3: Polymorphism statistics calculated with iMEC for different types of primers for the 31 taxa of woody bamboos based on fifteen ISSR primers data set...... 74 Table 5-4: Band patterns observed across 31 taxa of bamboos ...... 75 Table 6-1: ISSR primers used for PCR analysis for the study of Ethiopian lowland bamboo87 Table 6-2: Polymorphism of the nineteen ISSR primers on 13 populations of O. abyssinica along with molecular size ranges in bp...... 96 Table 6-3: Polymorphism statistics calculated with iMEC for different types of primers for the lowland bamboo ( O. abyssinica ) based on nineteen ISSR primers data set...... 97 Table 6-4: Band patterns observed across Ethiopian lowland bamboo populations using nineteen ISSR bands ...... 99 Table 6-5: Genetic diversity within populations and genetic differentiation parameters of thirteen populations of O. abyssinica...... 102 Table 6-6: Analysis of molecular variance (AMOVA) for thirteen populations of O. abyssinica with seven administrative Zonal groups and without grouping...... 104
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LIST OF FIGURES Figure 1-1: Invasive bamboo species and their associated region (Canavan et al., 2016)...... 5 Figure 2.1-1: Subtribe relationships and geographic distributions of the four major lineages of bamboos based on plastid (chloroplast) DNA sequences from five loci: ndhF , rpl16 intron, rps16 intron, trnD–trnT intergenic spacer, and trnL–trnF intergenic spacer. (Kelchner and BPG, 2013)...... 10 Figure 2.1-2: Worldwide distribution of bamboo. (A) Neotropical woody bamboos, (B) Temperate woody bamboos, (C) Paleotropical woody bamboos, and (D) Herbaceous bamboos (http://www.eeob.iastate.edu/bamboo/maps.html)...... 12 Figure 2.1-3: Schematic gene map representation of some woody bamboo chloroplast genomes (Zhang et al., 2011; Wu et al., 2015). Inner thick arcs represent the inverted repeat regions (IRA; IRB), large and small single copy (LSC; SSC) region. Genes inside and outside of the circle are transcribed clockwise and counterclockwise and colored according to their functional groups. *: genes used for the study...... 21 Figure 3-1: MP revealed genomic relationships among 31 taxa of Bambusoideae along with reference sequences (with accession numbers starting from “NC”) from NCBI using matK, ndhF and rps16 genes of cpDNA. The indigenous bamboo species are written in red font color and pointed with arrow...... 31 Figure 3-2: ML revealed genomic relationships among 31 taxa of Bambusoideae along with reference sequences using matK , ndhF and rps16 genes of cpDNA. The indigenous bamboo species are written in red font color and pointed with arrow...... 32 Figure 3-3: NJ revealed genomic relationships among 31 taxa of Bambusoideae along with reference sequences using matK gene of cpDNA. The indigenous bamboo species are written in red font color and pointed with arrow...... 34 Figure 3-4: NJ revealed genomic relationships among 31 taxa of Bambusoideae along with reference sequences using (A) ndhF and (B) ndhF plus matK genes of cpDNA. The indigenous bamboo species are written in red font color and pointed with arrow...... 35 Figure 3-5: NJ revealed genomic relationships among 31 taxa of Bambusoideae along with reference sequences using (A) rps16 and (B) cumulative of matK , ndhF and rps16 genes of cpDNA...... 36
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Figure 3-6: NJ revealed genomic relationships among 31 taxa of Bambusoideae along with reference sequences and Ethiopian lowland bamboo ( O. abyssinica ) using matK , ndhF and rps16 genes of cpDNA (I) - Bambusoideae (tropical woody bamboo) and (II) - Arundinareae (temperate woody bamboo)...... 37 Figure 4-1: (A) Bamboo cover map of Ethiopia (Zhao et al., 2018), (B) Map of Ethiopia with sample collection area and (C) Map of the sample collection area ...... 43 Figure 4-2: The Maximum Parsimony tree of O. abyssinica obtained based on pair-wise distance from the combined data of matK, ndhF and rps16...... 49 Figure 4-3: The neighbor joining tree of O. abyssinica obtained based on pair-wise distance from the combined data of matK, ndhF and rps16...... 50 Figure 4-4: The NJ tree obtained based on pair-wise distance from each genes A. matK , B. ndhF , and C. rps16 gene...... 51 Figure 4-5: Haplotype network of the combined cpDNA region obtained based on (A) gaps/missing data considered and (B) gaps/missing data not-considered...... 52 Figure 4-6: Frequency and percentage of InDel polymorphism of Ethiopian lowland bamboo (O. abyssinica )...... 55 Figure 4-7: DNA divergence between different Zones of Ethiopian lowland bamboo populations...... 57 Figure 5-1: A representative of ISSR electrophoresis profile of 31 species of bamboo using ISSR A) UBC-835, B) UBC-873 and C) UBC-841 (single sample representative for fourteen bamboo species)...... 70 Figure 5-2: UPGMA dendrogram depicting clustering patterns for 31 taxa of bamboo based on Jaccard’s similarity coefficient. A. Aggregate of total primers, B. Di-nucleotide also 3’ anchored, C. Tri-nucleotide, D. Tetra-nucleotide, E. Penta-nucleotide, F. 3’ anchored, G. 5’ anchored, H. 3’ and 5’ anchored and I. Unanchored ISSR primers...... 80 Figure 5-3: Three-dimensional representation of principal coordinate analysis of genetic relationships among 31 species of bamboo inferred from similarity matrix using (A) the Jaccard’s index using STATISTICA and (B) Pearson PCA method using XLSTAT...... 82 Figure 6-1: A representative of ISSR electrophoresis profile of 13 populations of O. abyssinica using ISSR markers A) UBC-834, B) UBC-845 and C) UBC-888...... 94
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Figure 6-2: UPGMA based dendrogram for thirteen O. abyssinica populations based on Jaccard’s similarity coefficient using ninteen ISSR primers...... 106 Figure 6-3: NJ analysis of 130 individuals based on Jaccard’s similarity coefficient...... 106 Figure 6-4: UPGMA dendrogram depicting clustering patterns for thirteen populations of O. abyssinica based on Jaccard’s similarity coefficient. A. Di-nucleotide also 3’ anchored, B. Tri- nucleotide, C. Tetra-nucleotide, D. Penta-nucleotide, E.5’ anchored, F. 3’ and 5’ anchored and G. Unanchored ISSR primers...... 107 Figure 6-5: Three-dimensional representation of principal coordinate analysis of genetic relationships among 130 individuals of 13 populations of Ethiopian lowland bamboo ( O. abyssinica ) inferred from similarity matrix using (A) the Jaccard’s index at STATISTICA and (B) Pearson PCA method using XLSTAT...... 109 Figure 6-6: STRUCTURE harvester and CLUMPAK Delta K value estimated using Evano et al. (2005) method and Bayesian model-based estimation of population structure for 130 Ethiopian lowland bamboos ( O. abyssinica ) based on ISSR markers in thirteen pre-determined populations. ( A), ΔK = mean(|L”(K)|)/sd(L(K)). ΔK = 11 indicates the maximum K value; (B), rate of change of the likelihood distribution (mean); (C), mean of estimated Ln probability; (D), absolute value of the 2 nd order rate of change of the likelihood distribution (mean). ... 110
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LIST OF APPENDICES Appendix 1 : SNPs based AMOVA result using GenAlex ...... 142 Appendix 2: Some of Ethiopian lowland bamboo ( O. abyssinica ) sample collection sites. 143 Appendix 3: DNA Dragon sequence alignment and nucleotide peaks for one of cpDNA gene ndhF ...... 144 Appendix 4: MAFFT alignment...... 144 Appendix 5: MEGA realignment...... 145 Appendix 6: Sequence submission to NCBI via Sequin...... 145
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LIST OF ABBREVIATIONS AMOVA Analysis of molecular variance BLAST Basic local alignment search tool BPG Bamboo phylogeny group cpDNA Chloroplast DNA CE-EFRC Central Ethiopia Environment and Forest Research Center CTAB Cetyltrimethyl ammonium bromide CUI COMSATS University Islamabad Dx Average number of nucleotide substitution per site between populations FAO Food and Agricultural Organization GPS Global positioning system He Expected heterozygosity/Nei’s gene diversity Ho Observed heterozygosity I Shannon information index INBAR International network for bamboo and rattan InDel Insertion-Deletion ISSR Inter simple sequence repeats k Average number of nucleotide differences per-sequence MAFFT Multiple sequence alignment software MEGA Molecular evolutionary genetics analysis MP Maximum parsimony MUSCLE Multiple sequence comparison by log-expectation Na Number of alleles NCBI National Centre for Biotechnology Information Ne Number of effective allele NJ Neighbor joining PCoA Principal coordinate analysis RAPD Randoml amplified polymorphic DNA RFLP Restriction fragment length polymorphism θw Population mutation rates per 100 sites π(t) Nucleotide diversity per-site xiii
ABSTRACT Phylogenetic Relationships among Indigenous and Introduced Bamboo Species and Genetic Diversity Study of Ethiopian Lowland Bamboo [Oxytenanthera abyssinica (A. Rich.) Munro] Using cpDNA Genes (matK , ndhF and rps16 ) and ISSR Markers
Oumer Abdie Addis Ababa University, July 2020.
Bamboo is one of the most important non-timber forest resources with potential alternative to wood and wood product, and is recognized as one of fastest-growing plant in the world (100 cm per day). There are two indigenous woody bamboo species in Ethiopia: the highland bamboo (A. alpina ) and the lowland bamboo (O. abyssinica ). There are more than 40 species of bamboo introduced to this country and those are under multiplication in different sites together with previously introduced ones. Although bamboos have immense ecological and economic importance, scientific inquiry particularly on phylogenetics on indigenous vs introduced bamboos as well as genetic diversity on lowland bamboo in Ethiopia is lacking substantially. CTAB solution immersed and silica-gel dried young leaves from 31 species of bamboo and 13 populations of Ethiopian lowland bamboo ( O. abyssinica ) were collected for DNA extraction and PCR amplification. DNA of each site was isolated separately using a modified CTAB DNA isolation method. PCR products were analyzed using 1% agarose gel electrophoresis and purified and pair-end sequenced. Each of the sequences of amplified cpDNA alignments were used to calculate an average number of nucleotide differences (k), nucleotide diversity (π) and population mutation rates per 100 sites (θw), InDel (Insertion-Deletion), DNA divergence, gene flow and genetic differentiation and to construct network analysis, neighbor-joining (NJ), maximum parsimony (MP) and maximum likelihood (ML) trees. Each of the amplified ISSR fragments were used to study band pattern and heterozigosity, level of polymorphism, calculate marker efficiency, Nei`s genetic diversity (H), Shannon diversity index (I), analysis of molecular variance (AMOVA), analysis for cluster, principal coordinates (PCoA), and admixture results. The total sequence generated by cpDNA genes viz. matK , ndhF and rps16 were 1,790 for phylogenetics and 3,694 for genetic diversity study. In the aggregate cpDNA genes, average GC and AT content and total sequence was observed (66.49, 33.51 and 3508.41). Highest AT content (67.4) in G. ampelxifolia and least (66.2) in D. diannanesis was observed by the aggregate genes. cpDNA genes based phylogenetics study shows, mostly O. abyssinica was clustered with genus Bambusa whereas, A. alpina was clustered with genus Phyllostachys . Ethiopian lowland bamboo collected from Gambella region associated differently than other O. abyssinica samples and mostly it is associating with genus Bambusa and Gigantochloa . ISSR based phylogenetics also gives almost similar result with cpDNA genes with few inconsistencies to choose the closest taxa. Partitioning xiv of genetic diversity by analysis of molecular variance (AMOVA) using grouped populations revealed that out of the total genetic diversity, most of the ISSR diversity was distributed within the populations (61.05%), with the remaining diversity being distributed among groups (31.80%) and among populations within groups (7.15%) with F ST = 0.38949, FSC = 0.10486 and F CT = 0.31797. AMOVA with and without grouping revealed the same patterns of genetic diversity and support the larger genetic diversity found within the populations rather than among the populations and are similar to Shannon’s diversity index. Likewise, cluster analysis in all the cases grouped the populations into sharply distinct clusters, which could be attributed to cross pollination nature of the plant and long lived to the area. STRUCTURE analyses for all population gives a result of K = 2. In this study, we provide the first assessment of the phylogenetic relationships of the indigenous and introduced bamboo species and the first wide assessment of genetic diversity, population structure, and gene flow analysis of Ethiopian lowland bamboo (O. abyssinica) using cpDNA genes and ISSR markers. The closest bamboo species for indigenous Ethiopian bamboos were identified and the extent of genetic diversity, gene flow and population structure of O. abyssinica populations also examined. The closest species for lowland bamboo was B. lapidea and B. longinternode where as, highland bamboo was P. pubescenc and P. edulis . Ethiopian lowland bamboo collected from Gambella region associated differently than other O. abyssinica samples and mostly it is associating with genus Bambusa and Gigantochloa . Both cpDNA genes and ISSR markers show Metekel zone of B-Gumuz region was the most diversified population and needs more conservation attention. We believed this is important for understanding the plant's genetic diversity and structure for its conservation and management and to study the phylogenetic relationships of indigenous and introduced bamboo species.
Key words : Bamboo, cpDNA genes, evolutionary tree, gene flow and genetic differentiation, indigenous vs introduced bamboos, ISSR primers, Oxytenanthera abyssinica, population structure, phylogenetics.
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CHAPTER ONE
1. General Introduction
1.1. Background
Bamboo is a member of the grass family (i.e., Poaceae ) and constitutes a single subfamily
Bambusoideae with 121 genera and 1,662 species (Bamboo Phylogeny Group (BPG),
2012; Goyal et al., 2013; Chokthaweepanich, 2014; Canavan et al., 2016). It is one of the most important non-timber forest resources or a potential alternative to wood and wood product (Ekhuemelo et al., 2018) and fastest-growing plant in the world (100 cm per day)
(Zhang et al., 2002; Li et al., 2020).
Bamboo serves as an important part of nature-based development. Known in some parts of the world as “green gold”, “poor man’s timber”, this fast ‐growing grass plant covers over
31.5 million hectares (ha) of land across the tropics and subtropics. Bamboo plants has been proven to help combat a number of global challenges, including rural poverty, land degradation, deforestation, urban development, unsustainable resource use (or reducing pressure on forestry resources) and climate change (Yuen et al., 2017; Ekhuemelo et al.,
2018; Kaushal et al., 2018; Bau and Trinh, 2019). Two and half billion people are estimated to be directly involved in the production and consumption of bamboos (Scurlock et al.,
2000).
Bamboo a multi-purpose plant with over 10, 000 documented uses and applications, with rapid regeneration capacity and the possibility of annual harvesting within a few years of planting has significant advantages over the other forest species (Diver, 2006; Akinlabi et al., 2017). It has been also proven to address a number of global challenges and contributes to United Nations Sustainable Development Goals: SDG 1 (no poverty), SDG 7 (affordable and clean energy), SDG 11 (sustainable and resilient housing), SDG 12 (efficient use of resources), SDG 13 (address climate change); and SDG 15 (life on land) (Yuen et al., 2017;
Ekhuemelo et al., 2018; Kaushal et al., 2018; Bau and Trinh, 2019). Due to its potential for soil erosion and water recharge, bamboo also provides an opportunity for restoration of degraded areas and watershed development (Kaushal et al., 2019; Kaushal et al., 2020).
Furthermore, bamboo is an herbal medicine for a mild case patients for currently occurred
outbreak corona virus disease (COVID-19) (Xu and Zhang, 2020; Shahrajabian et al.,
2020), a food for humans (researcher observed youngsters collecting newly growing shoots
for food in Kemash, Yasso, Manbuk, and Guba districts and generally newly growing
shoots are common for human food consumption in Benishangul-Gumuz Region (BGR))
and feed and fodder for livestock, and it contributes to ensuring food security (Halvorson
et al., 2011; Choudhury et al., 2012; Nongdam and Tikendra, 2014; Mulatu et al., 2019;
Andriarimalala et al., 2019). Bamboo has huge economic potential; the global production
and local consumption are estimated at the USD 60 billions, and the international export is
valued at USD 2 billion per annum (International Network for Bamboo and Rattan
(INBAR), 2019).
Bamboo matures in 3 - 5 years and thereafter can be harvested annually for about 20 years
(Tariyal, 2016; Dalagnol et al, 2018) or longer, depending on the gregarious flowering period, after which bamboo dies. The bamboo gregarious flowering interval can be between 20 and 120 years, depending on the species (Bau and Trinh, 2019).
2
Bamboo plant grows naturally in areas receiving annual rainfall ranging from 1,200 to
4,000 mm, with an average annual temperature of 8 to 36 ° C. They also can grow well in different soil types, ranging rich alluvium to hard lateritic, sandy, and loamy soils. The multi - functional use of bamboo grass taking into account its rapid growth rates, resilience, and the possibility of multiple harvesting in a few years time are significant advantages over the other forest species (Diver, 2006; Akinlabi et al., 2017).
Most common and useful bamboos are those with “woody” (lignified) stems belonging to the tribes Bambuseae and Arundinarieae that show a wide geographical and altitudinal distribution. The roughly 1,300 woody bamboo species often play critical roles in maintaining the ecology of forest habitats and have great economic importance to humans
(Kelchner and BPG, 2013). Herbaceous bamboos (tribe Olyreae) differ from woody bamboos they have not or only weakly lignified culms, usually no culm leaves, and no outer ligules. In addition, they are less popularly known and they are found in tropical forests, predominantly in the New World (BPG, 2012; Kelchner and BPG, 2013).
Phylogeny is the descent history of a group of taxa such as species from their common ancestors including the branching order and even the divergence periods. The expression
"phylogeny" comes from a combination of Greek words. Phylon means "tribe" or "clan" or "race" and genesis mean "source" or "origin." It may have a meaning in genealogy of genes; derived from a common ancestral gene and in molecular phylogeny, the relationships among organisms or genes are studied by comparing DNA homologues or protein sequences. Dissimilarities among the sequences indicate genetic divergence as a
3 result of molecular evolution during the course of time. Major sources of information for molecular evolutions are; morphological characteristics of an organism in classical phylogenetics and nucleotide sequences of DNA, RNA and sequences of amino acids of a protein of molecular approaches. By comparing homologous molecules from different
organisms, it is possible to establish their degree of similarity thereby establishing or
revealing a hierarchy of relationship (Patwardhan et al., 2014).
Genetic diversity is crucial for the effective conservation, management, and efficient
utilization of plant genetic resources, basis of an organism’s ability to adapt to changes in its environment, and can be affected by many factors (Amos and Harwood, 1998).
Environmental (e.g. temperature and precipitation) and geographical (e.g. landscape, latitude, longitude and altitude) factors affect the species genetic diversity and population structure and individuals among populations (Wellenreuther et al., 2011; Pauls et al.,
2013).
1.2. Statement of the problem
The multipurpose function and use of bamboos has led to many species being intentionally moved outside of their native ranges (Canavan et al., 2016). Species movement is often
influenced by its direct human value (McKinney and Lockwood, 1999). Morphological
features have been shown to be significant in promoting the introduction of species (Pysek
and Richardson, 2007). Some traits at the introduction level may be of high value to
humans and thus influence the initial movement of these species into new ranges (Canavan et al., 2016).
4
Bamboos have seen a rise in popularity over the past few decades, driven largely by a view of certain species as wonderful plants or miracle crops, i.e., plants that are thought to be valuable in meeting current economic, environmental and social needs (Hoogendoorn and
Benton, 2014; Liese and Köhl, 2015). In addition, modern processing methods have expanded the product range that can be made from bamboo. Therefore, the rate of introduction and cultivation of species in new areas has increased; in particular, bamboo cultivation in response to increased global demand for timber products (Hunter, 2003;
INBAR, 2003). But out of 1,662 species in 121 genera of Bambusoideae, 232 species
(14%) have been introduced outside of their native ranges and 12 species (0.7%) (Figure
1-1) were found to be invasive (Canavan et al., 2016).
Figure 1-1: Invasive bamboo species and their associated region (Canavan et al., 2016).
5
Genetic erosion of bamboo and their wild relatives are accelerating at a high rate because of human activities such as deforestation, wild firing, overexploitation and introduction of exotic species without investigation and proper research on the potential impact of genetic pollution and general problems associated with transfer of exotic germplasm (Canavan et al., 2016). Ethiopia introduced around twenty-three new species of bamboo in two rounds since 2007. The first entries were by the Ministry of Agriculture and INBAR. Seven species of the 1st entries have been tested for their adaptability and growth performance in different locations without adequate studies and inquiry. The second entries that comprise sixteen species were introduced by Morel Agroindustries LTD. These species are under multiplication at Holetta and Gurd-shola nurseries of CE-EFRC, Addis Ababa (Yigardu et al., 2016). Generally, there are more than 40 species of bamboo introduced to the country and they are under multiplication in different places of the country together with previously introduced bamboo species. Pakistan has also three species that grows naturally and introduced twenty-five species of bamboo from Bangladesh, Thiland and China.
The study by Bystriakova et al. (2004), indicated that as many as half of the world`s woody bamboo species have become vulnerable to extinction as a result of massive forest destruction. The most important problems currently facing bamboos in Ethiopia are related to high abandonment of bamboo plant due to lack of sufficient knowledge on its biology and genetics, presence of high genetic erosion and destruction of the plant due to human activities (Grand Ethiopian Renaissance Dam (GERD) with catchment area of 172, 250 km 2 (Abtew & Dessu, 2019) is built primarily on major lowland bamboo growing areas of
Metekel Zone of BGR. The lack of research studies conducted in Ethiopia especially on
6 the phylogenetics of the introduced bamboo species, diversity and systematics of O.
abyssinica at DNA level prompted the commencement of this research. Therefore, for the present study, we sequenced coding ( matK and ndhF ) and non-coding ( rps16 ) regions of
cpDNA genes and we used 38 ISSR primers aiming to assess the genetic diversity, population structure, and gene flow analysis of Ethiopian lowland bamboo ( O. abyssinica )
collected from lowland bamboo growing areas of the country and to observe the phylogenetic relationships of 31 taxa of bamboos with the indigenous bamboos of Ethiopia.
1.3. Hypothesis
The following null hypotheses have been stated;
- There is a high phylogenetic relationship between introduced and Ethiopian
indigenous bamboo species.
- Ethiopian indigenous bamboo species is distinct as compared to the introduced.
- The sequence based cpDNA and ISSR markers show the same phylogenetics
pattern among introduced and indigenous bamboo species and identify the same
closest species to the Ethiopian bamboos.
- There is high genetic diversity within thirteen populations of Ethiopian lowland
bamboos ( O. abyssinica )
- Genetic distance goes with geographic distance
7
1.4. Objectives
1.4.1. General Objective
To investigate the phylogenetic relationship of the indigenous and introduced bamboo species, to assess the extent of genetic diversity and population structure of lowland bamboo populations and to generate information for conservation and sustainable use of bamboo resources in Ethiopia.
1.4.2. Specific objectives
- To investigate the phylogenetic relationship of the indigenous and introduced
bamboo species and identify closest species to the Ethiopian and Pakistani bamboos
using selected cpDNA genes.
- To investigate the genetic relationship of introduced and indigenous bamboo
species and identify closest species to the Ethiopian and Pakistani bamboos using
selected ISSR primers.
- To screen and develop polymorphic cpDNA genes and ISSR markers.
- To determine the level of genetic variation and its patterns of distribution that exist
within and among Ethiopian lowland bamboo populations using cpDNA genes and
ISSR primers.
- To design relevant recommendations on sustainable development and management
system regarding the phylogenetics on introduced bamboo species and genetic
diversity of Ethiopian lowland bamboo populations.
8
CHAPTER TWO
2. Literature Review
2.1. Taxonomy of Bamboo
Bamboo is an arborescent perennial, giant and wood like grass appears to be the most successful and diverse conspicuous group of plants belonging to order Poales, family
Poaceae (grass family), subfamily Bambusoideae and tribe Bambuseae (Ohrnberger, 1999;
Grass Phylogeny Working Group (GPWG), 2001; Bamboo Phylogeny Group (BPG),
2012; Goyal et al., 2013; Chokthaweepanich, 2014; Canavan et al., 2016; Vorontsova et al., 2016), encompassing 121 genera in ca. 1,662 species (Canavan et al., 2016;
Vorontsova et al., 2016) and 100 species are commercially cultivated around the world (Li et al., 2020).
.
Based on molecular and morphological characteristics, true bamboos (Bambusoideae) are greatly supported as a monophyletic lineage and categorized into three tribes (Figure 2:1):
Bambuseae (tropical woody bamboos), Arundinarieae (temperate woody bamboos) and
Olyreae (herbaceous bamboos) (Sungkaew et al., 2009; BPG, 2012; Kelchner and BPG,
2013; Saarela et al., 2018). The Bambuseae tribe differs from the Olyreae on the basis of
the presence of an abaxial ligules (Zhang and Clark 2000; Grass Phylogeny Working Group
(GPWG), 2001). Within the tribe Bambuseae, there are two clades comprising neotropical
woody bamboos (NWB) and paleotropical woody bamboos (PWB). The NWB clade is
composed of three subtribes: Guaduinae, Arthrostylidiinae, and Chusqueinae whereas
clade PWB has Bambusinae, Racemobambosinae, Melocanninae, and Hickeliinae sub-
tribes. The Olyreae contains three subtribes: Buergersiochloinae and Olyrinae Parianinae
9
(Clark et al., 2007; Sungkaew et al., 2009; BPG, 2012, Kelchner and BPG, 2013; Clark et al., 2015).
Figure 2.1-1: Subtribe relationships and geographic distributions of the four major lineages of bamboos based on plastid (chloroplast) DNA sequences from five loci: ndhF , rpl16 intron, rps16 intron, trnD–trnT intergenic spacer, and trnL–trnF intergenic spacer. (Kelchner and BPG, 2013).
2.2. Bamboo Cytogenetics, Ploidy Level and Genome Size
Chromosome records of woody bamboos show that seemingly consistent ploidy levels define each woody bamboo clade: PWB are mostly hexaploid; NWB, tetraploid; and the
Arundinarieae (temperate woody bamboos), also tetraploid. Woody bamboo genera have a typical basic chromosome number of x = 12, with the exception of Chusquea (x = 10)
(Pohl and Clark, 1992; Chen et al., 2004; Clark et al., 2010). The Ethiopian bamboos O.
10 abyssinica and Y. alpina has a chromosome number of 2n = 6x = 72 and 2n = 4x = 48
with basic chromosome number x = 6 and x = 4.
The previously reported higher number chromosome in bamboos was 2n = 108 recorded in Bambusa schizostachyoides (Kurz) Gamble (Sobita Devi and Sharma, 1993) followed by 2n = 104 in six Chinese species (Chen et al., 2004). But, 2n = 192 is the highest
chromosome number in the entire bamboo family reported for the first time in
Pseudoxytenanthera (Mathu et al., 2015).
Genome size assessments are useful in studying evolutionary and adaptation mechanisms.
Further, this information is pre-requisite for genome sequencing and analysis projects.
However, only 1 % of angiosperms have been investigated for DNA content estimations
(Bennett and Leitch, 1995). Moreover, such information is limited to only few species of bamboo. Flow cytometric studies explored genome size variation among temperate and
tropical bamboo species ranged from 2.04 Gb - 2.6 Gb in temperate and 1.14 Gb - 1.6 Gb
in tropical bamboo species (Gielis 1997). These inferences also suggest that polyploidy is
the imperative powerhouse in the evolution of woody bamboos. Recently, two independent
flow cytometric studies on 37 bamboo species (Kumar et al., 2011) and a tetraploid
Phyllostachys pubescens (Gui et al., 2007) showed that genome size in different bamboo
species ranges from 1.2 Gb to 2.9 Gb, which is slightly higher in range as compared to prior studies by Gielis (1997). Further, these estimates revealed that the genome sizes in bamboo species are more than three to seven folds larger than the genome sizes of
Nipponbare ( Japonica rice) and 10 - 24 times larger than Arabidopsis thaliana genome
11 size and much more smaller than bread wheat (allohexaploid 16 Gb) and durum wheat
(allotetraploid 11 Gb) species respectively (Ganal and Röder, 2007; Mayer et al., 2014).
2.3. Area Coverage and Geographical Distribution of Bamboo
Bamboo is widely distributed in the tropical, subtropical, and temperate countries in Asia,
Latin America, and Africa from sea level to highlands. (Figure 2-2) (BPG, 2012; GPWG
II, 2012; Kelchner and BPG, 2013). About 31.5 million hectares of the earth's surface is
covered by bamboos. The highest species richness is observed in Asia-pacific followed by
South America, while Africa has the least number of species (Bystriakova et al., 2003). It
has been reported that there are no native bamboo species in Europe and the Antarctica
(Zhao et al., 2018). According to the world bamboo resources assessment report, Ethiopia,
Kenya, and Uganda possess most of the bamboo resources in Africa (Lobovikov et al.,
2005; Zhao et al., 2018).
Figure 2.1-2: Worldwide distribution of bamboo. (A) Neotropical woody bamboos, (B) Temperate woody bamboos, (C) Paleotropical woody bamboos, and (D) Herbaceous bamboos (http://www.eeob.iastate.edu/bamboo/maps.html ).
12
2.3.1. Bamboo Distribution in Africa, Ethiopia and Pakistan
Africa has forty-three (43) species occurring on 1.5 million hectares. Of these, 40 are mainly found in Madagascar while the remaining three are in mainland Africa (Embaye,
2000). There are two indigenous woody bamboo species in Ethiopia: the African Alpine
Bamboo or highland bamboo (Yushane alpina K. Shumann Lin; synonym: Arundinaria alpina K. Schumann) and the monotypic genus lowland bamboo (Oxytenanthera
abyssinica A. Richard) Munro. These species occur in some other African countries, but nowhere other than the continent of Africa (Embaye, 2000; Ensermu et al., 2000). They
are indigenous to Ethiopia and endemic to Africa, confined to the sub-Saharan region
(Embaye, 2000). Ethiopia contributes to the leading coverage constituting more than 1.44 million hectares (Zhao et al., 2018). This constitutes about 67% of the total area of bamboo on the continent and 7% of the world (Embaye, 2000). The lowland bamboo (O. abyssinica ) in Ethiopia accounts for 85% of the total national coverage and the rest 15% is
covered by highland bamboo (A. alpina ) (Embaye, 2000; Embaye et al., 2003; FAO and
INBAR, 2005). The lowland bamboo covers a range of elevation between 540 to 1,750 m and highland bamboo at a higher elevation above 2,480 m (Zhao et al., 2018).
The major lowland bamboo (O. abyssinica) growing regions in Ethiopia are Benishangul -
Gumuz, Oromia, Gambella, Southern Nations Nationalities and Peoples (SNNPs),
Amhara and Tigray Regions. Benishangul - Gumuz Region (BGR) has 440,000 hectares of lowland bamboo (O. abyssinica ) which at present is mainly used for subsistence uses. The major African Alpine Bamboo (Y. alpina) growing regions in Ethiopia are Amhara, Oromia
13 and Southern Nations Nationalities and Peoples (SNNPs) and BGR (Embaye et al., 2003;
INBAR, 2010; Zhao et al., 2018).
Bamboos have limited diversity in Pakistan and all bamboo area is reported as private
(Lobovikov et al., 2007). Three species ( Arundinaria falcate, Bambusa bambos and
Dendrocalamus strictus ) grow naturally in Pakistan. The first one ( A. falcate ) grows in the
NW Himalayas at 1,200-2,000 m. It occurs in the undergrowth in forests of oak, firs and
mixed trees, usually on northern slopes or in ravines. It is part of a wider gene pool through
the Himalayas. It is used for making baskets, mats and pipes. The second species ( B.
bambos ) is extensively used for construction. The third species ( D. strictus ) is found in
Punjab and Kashmir. It is found also in mixed vegetation on Marghalla hills surrounding
Islamabad. It is used for construction and a variety of purposes. This forms part of a gene pool extending across Hindustan and usually growing below 1,200 m (FAO, 2006).
According to global forest resources assessment and INBAR (2005), Pakistan has introduced twenty-five species of bamboos. Twenty-one species were from Bangladesh and four species from Thiland and China. Bamboo plantations have been raised on good agricultural lands in Sargodha, Jhang, Khoshab and Mandibhaudin districts of Punjab province. Most of these plantations are on 0.5 acres of lands. In Chunian sub division of
Kasur district, smallholder farmers have also successfully established small bamboo groves of 4 - 10 acres area. Generally, in Pakistan the resources are shrinking and the plantation area increases or decreases with the market demand in the domestic as well as in the Middle East markets (FAO, 2006; Shah et al., 2013).
14
2.4. Assessment of Phylogenetics and Genetic Diversity Study
Phylogenetics is the study of evolutionary relationships among biological entity - often species, individuals or genes (may be referred as taxa) and phylogeny is the history of descent of a group of taxa such as species from their common ancestors including the order of branching and sometimes the times of divergence (Patwardhan et al., 2014). In the
genealogy of genes it might have explanation; derived from a common ancestral gene and
in molecular phylogeny, the relationships among organisms or genes are studied by
comparing homologues DNA or protein sequences. Dissimilarities among the sequences
indicate genetic divergence because of molecular evolution during the course of time
(Vandamme, 2003). Morphological characteristics of an organism in classical phylogenetics and nucleotide sequences of DNA, RNA and amino acids of a protein of
molecular approaches are major sources of information (Vandamme, 2003; Page and
Holmes, 2009; Patwardhan et al., 2014).
Determining phylogenetic relationship between different organisms is a difficult task as
the living world experiences incredible complexity with respect to its species material. This
diversity is not only reflected in phenotypic characters but also in ultra-structural, biochemical and molecular features. Phenotypically similar organisms may have distinct biochemical and molecular features. To understand and express biological terms, has to
know the organism’s evolutionary history since it is the result of an evolutionary process
(Patwardhan et al., 2014).
15
Molecular genetics research and assessment of genetic diversity and population structure is a prerequisite to promote genetic, evolutionary, functional studies of plants to have a comprehensive understanding of the biology and other key characteristics that enable to properly exploit plant resources in general and bamboo in particular (Das et al., 2008; Sui
et al., 2009; Peng et al., 2013). Genetic diversity and population structure within different populations of a particular species is the main building block for understanding
evolutionary and speciation aspects of that species. In addition, genetic diversity is the basis of an organism’s ability to adapt to changes in its environment, crucial for the
effective conservation, management, and efficient utilization of plant genetic resources and can be affected by many factors (Amos and Harwood, 1998). Geographical (e.g. landscape, latitude, longitude and altitude) and environmental (e.g. temperature and precipitation) factors affect the genetic diversity and population structure of a species and the individuals among populations (Wellenreuther et al., 2011; Pauls et al., 2013).
Genetic markers are important developments in the field of plant breeding and conservation
(Kebriyaee et al., 2012). Genetic marker is a morphological trait or gene or DNA sequence with a known chromosome location controlling a particular gene or trait. Genetic markers are closely related with the target gene and they act as sign or flags ( Collard et al., 2005) .
Genetic markers are broadly grouped into two categories: classical markers and
DNA/molecular markers. Morphological, cytological and biochemical markers are types
of classical markers. For the advancement and widely used molecular marker, one of the breakthroughs in biological sciences in general and molecular research in particular, is the
16 invention of Polymerase Chain Reaction (PCR) that amplifies DNA in vitro (Mullis and
Faloona, 1987). Since then, molecular marker techniques were grouped into non-PCR based and PCR-based, depending on the requirement of PCR or not to produce different
DNA fragments. Molecular markers are fragments or nucleotide sequences that can be investigated through the polymorphism present between the fragment and nucleotide sequences of different individuals. Insertion, deletion, point mutations duplication and translocation are basis of these polymorphisms; however, they do not necessarily affect the activity of genes.
An ideal DNA marker should be co-dominant, evenly distributed throughout genome, highly reproducible and having ability to detect higher level of polymorphism (Mondini et
al., 2009). Some examples of DNA markers that used for phylogenetics and genetic
diversity study are restriction fragment length polymorphism (RFLP), amplified fragment
length polymorphism (AFLP), simple sequence repeats (SSRs), inter simple sequence repeats (ISSRs), and single-nucleotide polymorphisms (SNPs) (Jiang, 2013).
Among molecular techniques used for phylogenetics and genetic diversity study, cpDNA genes are more common ( Qiang et al., 2005; Triplett et al., 2010; Goh et al., 2010;
Chokthaweepanich, 2014; Kelchner and BPG, 2013). ISSR markers are also used for phylogenetics and genetic diversity study of some bamboos (Wang et al., 2009; Mukherjee et al., 2010; Desai et al., 20015; Goyal and Sen, 2015).
17
2.4.1. Chloroplast Genes Based Phylogenetics and Genetic Diversity Study
Most molecular phylogenetic and genetic diversity studies on bamboos have utilized nuclear and/or plastid DNA sequences. Single-locus DNA regions were employed by the earlier phylogenetic studies, e.g., those using the cpDNA rpl 16 intron for the
Bambusoideae group in Poaceae (Zhang and Clark, 2000), for Chusquea (Kelchner and
Clark, 1997), and those using the nrITS region for Bambusa (Sun et al., 2005) and for
Alpine woody bamboos (Guo et al., 2001; Zhang et al., 2019). More recently, investigations have utilized combined DNA datasets from multiple DNA regions. This includes potentially more informative characters for resolving phylogenetic relationships at lower taxonomic levels, because different DNA regions evolve at different rates and could be helpful in resolving different parts of the phylogeny. A variety of studies have also revealed that multi-gene analysis provides better resolving power in phylogenetic studies of woody bamboos (Yang et al., 2007; Yang et al., 2008; Fisher et al., 2009;
Sungkaew et al., 2009; Yang et al., 2010; Triplett and Clark, 2010; Zeng et al., 2010).
Chloroplast or plastid is a cellular organelle resulting from endosymbiosis between independent living cyanobacteria and a non-photosynthetic host ~1.5 billion years ago
(Dyall et al., 2004). Each has its own genome that is usually non-recombinant and uniparentally inherited (Birky, 1995). Chloroplast genome of most higher plant have conserved quadripartite structure, consisting two copies of a large inverted repeat (IR) and two sections of unique DNA, which are referred to as the ‘‘large single copy regions
(LSC)’’ and ‘‘small single copy regions (SSC)’’ (Jansen et al., 2005).
18
Chloroplast DNA sequence and its characteristic for phyllogenetic and population genetics study is well known and strongly preferable due to its relative small size (compared to mitochondria and nuclear genome (Wagner, 1992)) and conserved region property (Kim et al., 1999; Chokthaweepanich, 2014; Attigala, 2015). In its evolution, it is assumed to be
conserved in terms of nucleotide substitution with very few rearrangements that allow the
molecule to be used to solve phylogenetic relations and taxonomic annomalies, especially
at deep levels of evolution (Kim et al., 1999).
The focus of plant molecular systematics has shifted towards to more rapid development of cpDNA loci. Simple genetics property, high copy within typical genomic DNA and structural stability makes cpDNA preferable for evolutionary and population genetics studies in many plants since it has protein-coding genes ( matK , ndhF , etc), introns ( trnL ,
rpll6 , rps16 , etc) and intergenic spacer (intergenic spacers between rbcL and atpB , trnT and trnL , trnL and trnF ) regions (Scarcelli et al., 2011; Daniell et al., 2016). As the evolutionary rates of cpDNA with nucleotide substitutions and structural changes are highly conserved (Soltis et al., 2004), both coding and non-coding cpDNA regions are used
to elucidate genetic diversity and population structure, the evolutionary relationships at the
generic and higher taxonomic levels (Shaw et al., 2007; Shaw et al., 2014).
In most angiosperms, matK gene is about 1,515 bp long within the trnK intron, and
functionally may be involved in splicing group II introns (Hilu et al., 1999). This gene's
effective application in plant systems has already been documented on phylogenetics and evolution of woody bamboo, phylogeny of legumes, Saxifragaceae, etc (Johnson and
19
Soltis, 1994, Wojciechowski et al., 2004, Chokthaweepanich, 2014). MatK is known to have relatively high rates of substitution compared to other chloroplast genes (Johnson and
Soltis, 1994). This gene exhibits a relatively high proportion of transversions and the 3' region of its open reading frame (ORF) has been shown to be extremely useful in resolving sub familial and to a certain degree tribal relationship in Poaceae.
The NADH dehydrogenase subunit F ( ndhF ) 3' end gene is ~1,140 bp long cpDNA coding region (Chokthaweepanich, 2014) and in most angiosperms, the ndh proteins associate the
NADH dehydrogenase like complex with nuclear-encoded subunits. This protein complex links with photosystem I for becoming a super-complex that mediates cyclic electron transport, produces ATP to adjust the ATP/NADPH proportion and facilitates chlororespiration when cyclic electron transport pauses during the night (Lin et al.,
2015).
The rps16 gene is a non - coding region of ~860 bp long cpDNA encoding the ribosomal protein S16 and is present in the chloroplast genome of most higher plants (Oxelman et al.,
1997; Chokthaweepanich, 2014).
20
Figure 2.1-3: Schematic gene map representation of some woody bamboo chloroplast genomes ( Zhang et al., 2011; Wu et al., 2015). Inner thick arcs represent the inverted repeat regions (IRA; IRB), large and small single copy (LSC; SSC) region. Genes inside and outside of the circle are transcribed clockwise and counterclockwise and colored according to their functional groups. *: genes used for the study.
Some of these cpDNA markers have been used on crops and trees of Ethiopian origin. To cite few, Coffea spp. (Tesfaye et al., 2007); Guizotia abyssinica (Geleta et al., 2010);
Ensete and Musa species (Bekele and Shigeta, 2011); Cordia Africana (Derero et. al.,
2011); Lobelia (Kebede et al., 2007; Geleta and Bryngelsson, 2012).
21
2.4.2. ISSR Based Phylogenetics, Genetic Diversity and Population Structure Study
An ISSR primer is typically 16 - 25 nucleotides in length and comprises mainly, or solely, of repeated DNA motifs (2 - 5 bp each) intended to be complementary to microsatellite regions in the genome. Depending on the implimentation, there are 3 forms of ISSR primers: (1) unanchored (primer consists only of a repeated motif, e.g. 5'-(AC) 8-3'), (2) 5'- anchored (primer consists of a repeated motif with one or several non-motif nucleotides at the 5'-end, e.g. 5'-GA(AC) 8-3'), and (3) 3'-anchored (primer consists of a repeated motif
with one or several non-motif nucleotides at the 3'-end, e.g. 5'-(AC) 8 AG-3') (Ng and Tan,
2015).
ISSR primers are used to study the phylogenetics and genetic diversity of different species of plants either in combination with other markers or solely. But the use of ISSR markers in bamboo in general and in O. abyssinica in particular is limited or none. The use of SSR
markers is limited by their lack of availability in bamboo; nevertheless, they have been
successfully applied to Phyllostachys (Lai and Hsiao 1997). Phylogenetics study of 22 taxa of bamboos using 12 ISSR primers (Mukherjee et al., 2015) and phylogenetics study of 29
species of bamboo using 16 ISSR primers (Goyal and Sen, 2015) are among the studies
used ISSR primers for phylogenetics study in bamboo.
These markers have been in use to study various crops and cereals of Ethiopian origin but few number of researches on trees and forest plants; to mention few, Eragrostis tef (Assefa et al., 2003); Wheat (Hailu et al., 2005); Hagenia abyssinica (Feyissa et al., 2007); Coffea
(Aga et al., 2005; Tesfaye et al., 2014); Rice (Girma et al., 2010); Enset ( Tobiaw and
22
Bekele, 2011; Getachew et al., 2014 ); Sesame (Admas et al., 2013; Abate et al., 2015;
Woldesenbet et al., 2015); Anchote (Bekele et al., 2014); White lupine (Oumer et al.,
2015); Black cumin (Birhanu et al., 2015); Sorghum (Teshome and Feyissa, 2013).
2.5. Phylogenetic Tree Construction Methods
The phylogenetic tree can be constructed by distance or character-based methods. Distance method transforms the sequence data into pair wise distances and then uses the matrix during tree building by ignoring characters. ME (minimum evolution) (Rzhetsky & Nei,
1993), NJ (neighbor joining) (Saitou & Nei, 1987), UPGMA (unweighted paired group method with arithmetic mean) (Murtagh, 1984) and FM (Fitch-Margoliash) (Fitch &
Margoliash, 1967) are among most commonly used distance-based methods. Character based method uses the aligned sequences directly during tree inference and optimizes the distribution of the actual data pattern for each character. Maximum Parsimony (MP)
(Sober, 1983) and Maximum Likelihood (ML) methods (Felsenstein, 1981) are among the most used character-based methods (Roy et al., 2014).
Computational speed, factual consistency of phylogenetic trees, consistency of evaluated topology, likelihood of getting the right topology, unwavering quality of assessed branch length, and so forth are among those criteria's relying upon which can think about various set up tree-building techniques (Roy et al., 2014). Based on computational speed and other parameters, NJ strategy from distance based is the prevalent one from other tree-building strategies which are at present being used. This method can handle a large number of sequences with bootstrap tests with ease whereas MP and ML from character based and
23
ME from distance-based methods examine all possible topologies searching for the MP,
ML and ME trees. In the case of ME, simplified advanced algorithms have been developed
that are efficient in time scales to obtain the correct tree and for MP methods, when the
number of sequences is relatively high, the branch and bound method is often used (Roy et
al., 2014; Binet et al., 2016).
During the estimation of distance through substitution, NJ and ME strategies are discovered
consistent for estimating trees but MP is often inconsistent (Roy et al., 2014; Binet et al.,
2016). Alternatively, from character-based methods ML methods have the added benefit
of being more flexible in the choice of the evolutionary model. But this method is lengthy
and time consuming (Roy et al., 2014; Binet et al., 2016). The algorithms used to create phylogenetic trees with phylogenetic characters are generally more complex than distance- based methods (Scott & Gras, 2012).
24
CHAPTER THREE
3. Phylogenetic Relationships among the Indigenous and Introduced
Bamboo Species using cpDNA Genes Sequences
3.1. Materials and Methods
3.1.1. Plant Materials and Sample Collections
Young fresh leaves of three individual plants from 31 species of woody bamboo (two
Ethiopian indigenous bamboo species, twenty seven introduced woody bamboo species from central Ethiopia environment and forest research center (CE-EFRC) and two from
Pakistan woody bamboo species) were collected for the study (Table 3-3). The leaves were immersed in 15ml falcon tube containing 2% CTAB solution.
3.1.2. DNA Extraction and Primer Screening
Three independent leaf materials from each species were used for DNA isolation. DNA was isolated separately using a modified CTAB DNA isolation method (Hyder et al., 2007) at the Biochemistry, Molecular Biology and Biotechnology (BMBB) laboratory,
Department of Biosciences, COMSATS University Islamabad (CUI), Pakistan. Test gel electrophoresis in 1% agarose and nanodrop (Implen Nanophotometer 190-1100nm spectrophotometer) of each sample was used to measure DNA quantity and quality. Those with high DNA quantity and quality were used for PCR amplification. Among ten primers selected from Chokthaweepanich (2014) and Attigala (2015) and designed via Primer3
(http://bioinfo.ut.ee/primer3-0.4.0/ ), three chloroplast sequences with coding ( matK and ndhF ) and non-coding ( rps16 intron) were PCR amplified (Table 3-1).
25
Table 3-1: cpDNA primer sequences, their approximate amplified size and PCR profile. Amplification PCR Profile Primer Amplified Primer Sets pattern (All end with name size (bp) 4ºC hold) matK F: CGT TCT GAC CAT ATT GCA CTA TG ~1,350 Excellent 96 °C, 3 min.; R: AAC TAG TCG GAT GGA GTA G 35X (96 °C, 30 ndhF F: GTC TCA ATT GGG TTA TAT GAT G ~1,140 Excellent sec., 53, 30sec., (3'end) R: CCC CCT AYA TAT TTG ATA CCT TCT CC 72 °C 1 min.); rps 16 F:AAA CGA TGT GGT ARA AAG CAA C ~860 Excellent 72 °C, 20 min. R:AAC ATC WAT TGC AAS GAT TCG ATA rpl16 F: GCTATGCTTAGTGTGTGACTCGTTG ~ 1,100 R: CGTACCCATATTTTTCCACCACGAC trnD- F: ACCAATTGAACTACAATCCC ~ 1,100 trnT R: CCCTTTTAACTCAGTGGTA trnT- F: CATTACAAATGCGATGCTCT ~ 880 trnL R: TCTACCGATTTCGCCATATC matKO ~ 1,754 F: CGTCTACCCACTTCTCTTTCAGG R: GGGTTCACCAGGTCATTGATAC psbA ~610 F: GGAAGGAAAGCCAGAAATACCC R: ACAATCCAC TGCCTTGATCC KUN ~1,215 F: CAGAACAACCGTACGTGAGC R: TTCCAGGAGAGATCCTGAGC bad amplificationpattern. GPA1 ~1,155 F: GCTCAAGGGTTACAACTGAAGTCC R: CGCACCTCCAGATCATAAGC Rejected due to andnon reproducible
3.1.3. PCR Product Profiling, Sequencing and Alignment
PCR reaction (50µl per reaction) and amplification contained 7.50µlof 50 - 100ng/µl template DNA, 5.0µl Taq buffer (100mM Tris-HCl, 500mM KCl, 15mM MgCl 2, pH 8.5
(25 oC), 5.0µl dNTPs mix (2.5mM each), 2.5µl Taq DNA Polymerase (5U/µl) (WizPure™
Taq DNA Polymerase), 1.25µl 25pM of each primer and 28.75µl of PCR grade H 2O. The thermal profile for all primer sets included pre-PCR denaturation at 96°C for 3 min. followed by 35 cycles of denaturing at 96°C for 30 seconds, annealing at 53°C for 30 seconds, extension at 72°C for 1 min. a final extension at72°C for 20 min. and hold at 4°C.
3.0µl PCR products were analyzed using standard 1% agarose gel electrophoresis and purified and paired-end sequenced at commercial sequencing facility of Macrogen, Inc.
(Seoul, Korea).
26
The sequence of both strands of every fragment amplified from each sample was assembled separately using DNA Dragon version 1.6.0 and each district was represented by a single sequence with the one very identical and informative among the triplicate samples. The assembled sample was submitted to the GenBank and used for sequence analysis. BLAST searches for each target sequence were used to confirm probable homology (Query cover,
Identity percentage, E-value and Direction of the strand).
Sequences of three genes from thirty one taxa together with nine reference sequences retrived from NCBI were arranged in FASTA format and aligned in MAFFT (multiple sequence alignment software version 7) (Katoh and Standley 2013) and realigned again using MEGA version 7.0 to increase the quality of final alignment product. Sequence information for submission to NCBI was prepared by bankit
(https://www.ncbi.nlm.nih.gov/WebSub/ ) and Sequin v5.51. An accurate and complete
GenBank record or accession number is described in Table 3-2.
3.1.4. Phylogenetics Analyses
The three markers ( matK, ndhF and rps16 ) were analyzed separately and then combined into a single data set. The sequence alignments with MUSCLE (multiple sequence comparison by log-expectation) were used to identify the best nucleotide substitution model and construct MP and ML tree using MEGA 7.0 (Tamura et al., 2013).
To construct MP tree, bootstrap analysis with 1000 replicates was conducted to estimate nodal support. The percentage of replicate trees in which the associated taxa clustered
27 together in the bootstrap test greater than 50% was placed on the branches (Felsenstein,
1985) (Felsenstein 1985). The MP tree was obtained using the Subtree-Pruning-Regrafting
(SPR) algorithm (Nei & Kumar, 2000) with search level 1 in which the initial trees were obtained by the random addition of sequences (10 replicates). The tree is drawn to scale, with branch lengths calculated using the average pathway method and are in the units of the number of changes over the whole sequence. The analysis involved 40 nucleotide sequences. All positions containing gaps and missing data were eliminated.
In the case of ML tree construction method, initial tree(s) for the heuristic search were obtained automatically by applying Neighbor-Join and BioNJ algorithms to a matrix of pairwise distances estimated using the Maximum Composite Likelihood (MCL) approach, and then selecting the topology with superior log likelihood value. The analysis involved
40 nucleotide sequences. All positions containing gaps and missing data were eliminated.
Evolutionary analyses were conducted in MEGA7 (Kumar et al., 2016).
Neighbor-joining (NJ) tree analyses with each separate and combined cpDNA genes were conducted using the Kimura’s two-parameter distance correction mode to construct a phylogenetic tree. The evolutionary distances were computed using the Maximum
Composite Likelihood method (Tamura & Nei, 1993) and are in the units of the number of base substitutions per site. The analysis involved 31 samples of target sequences plus 9 references from NCBI nucleotide sequences. All positions containing gaps and missing data were eliminated. Evolutionary analyses were conducted in MEGA7 (Kumar et al.,
2016).
28
3.2. Results
3.2.1. Chloroplast DNA Sequence Character and Sequence Divergence
3.2.1.1.GC and AC content analysis
GC and AT content of each and aggregate cpDNA genes were analyzed (table 3-2). Highest
AT content (67.4) in G. ampelxifolia and least (66.2) in D. diannanesis was observed by the aggregate genes while the GC content was highest (34.2) in D. diannanesis and the least was observed in G. ampelxifolia (32.6). Average GC and AT content and total sequence was observed (66.49, 33.51 and 3612.58) in the aggregate cpDNA genes respectively.
Highest AT content using matK gene was observed in G. ampelxifolia (67.7) and the least by D. diannanesis (65.8). Highest AT content (67.0) in D. brandisii and least (66.2) in G. atter, B. vulgaris (Green), P. pubescens and A. alpine (Eth_HB) was observed by ndhF gene. Wheras the highest AT content using rps16 gene was observed in G. ampelxifolia
(66.3) and the least by B. vulgaris (Green), P. pubescens, B. multiplex, D. membranaceus
Cx Grandis, G. angustifolia and B. chungii (Pks_WB) (65.7). Species that has highest AT
content percentage will have least GC content and vise versa.
Ethiopian lowland bamboo observed to have (66.3, 33.7 and 3661) GC and AT content and
total sequence and highland bamboo observed (66.5, 33.5 and 3573) GC and AT content
and total sequence. Result of GC and AT content on Ethiopian bamboos were not far from
the average but total sequence was observed higher in lowland bamboo.
29
Table 3-2: GC and AT content of each and aggregate cpDNA genes. matK (~ 1,350 bp) ndhF (~ 1,140 bp) rps16 (~ 860 bp) Aggregate genes Name of the species Percentage Total Percentage Total Percentage Total Percentage Total AT GC Sequence AT GC Sequence AT GC Sequence AT GC Sequence G. sumatra (Black) 66.4 33.6 1766.0 66.5 33.5 1046.0 65.8 34.2 860.0 66.5 33.5 3601.0 D. latiflorus 66.2 33.8 1766.0 66.7 33.3 1044.0 65.8 34.2 860.0 66.4 33.6 3664.0 G. ampelxifolia 67.7 32.3 1773.0 66.9 33.1 1044.0 66.3 33.7 860.0 67.4 32.6 3616.0 G. apus 66.2 33.8 1766.0 66.6 33.4 1044.0 66.0 34.0 860.0 66.4 33.6 3675.0 P. dulcis 66.2 33.8 1766.0 66.6 33.4 1044.0 66.0 34.0 860.0 66.5 33.5 3667.0 G. atter 66.4 33.6 1766.0 66.2 33.8 1044.0 65.8 34.2 843.0 66.3 33.7 3662.0 D. barbatus 66.1 33.9 1766.0 66.6 33.4 1044.0 65.9 34.1 860.0 66.3 33.7 3671.0 B. polymorpha 66.4 33.6 1766.0 66.6 33.4 1044.0 65.9 34.1 860.0 66.5 33.5 3655.0 D. diannanesis 65.8 34.2 1765.0 66.8 33.2 1044.0 65.8 34.2 860.0 66.2 33.8 3661.0 D. fuminesis 66.1 33.9 1766.0 66.7 33.3 1044.0 65.9 34.1 860.0 66.4 33.6 3622.0 D. asper 66.1 33.9 1766.0 66.6 33.4 1044.0 65.8 34.2 860.0 66.4 33.6 3652.0 B. vulgaris (Green) 66.5 33.5 1766.0 66.2 33.8 1044.0 65.7 34.3 860.0 66.4 33.6 3651.0 P. pubescens 66.5 33.5 1775.0 66.2 33.8 1044.0 65.7 34.3 843.0 66.4 33.6 3600.0 G. sumatra (Green) 66.5 33.5 1766.0 66.5 33.5 1044.0 65.8 34.2 860.0 66.6 33.4 3628.0 B. oldhamii 66.5 33.5 1766.0 66.6 33.4 1044.0 65.8 34.2 860.0 66.5 33.5 3652.0 D. gigantus 66.3 33.7 1766.0 66.6 33.4 1044.0 65.9 34.1 860.0 66.5 33.5 3607.0 B. multiplex 66.3 33.7 1763.0 66.4 33.6 1044.0 65.7 34.3 860.0 66.6 33.4 3538.0 D. hamilitonis 66.2 33.8 1766.0 66.6 33.4 1044.0 65.9 34.1 860.0 66.4 33.6 3581.0 A. alpine (Eth_HB) 66.5 33.5 1775.0 66.2 33.8 1044.0 65.8 34.2 843.0 66.5 33.5 3573.0 D. sinicus 66.2 33.8 1766.0 66.8 33.2 1044.0 65.9 34.1 860.0 66.5 33.5 3544.0 D. membranaceus Cx Grandis 66.2 33.8 1766.0 66.7 33.3 1044.0 65.7 34.3 860.0 66.5 33.5 3583.0 D. laosenesis 66.5 33.5 1766.0 66.5 33.5 1044.0 65.8 34.2 860.0 66.5 33.5 3569.0 B. vulgaris (Yellow) 66.5 33.5 1766.0 66.5 33.5 1042.0 65.8 34.2 860.0 66.5 33.5 3573.0 B. tulda 66.3 33.7 1766.0 66.7 33.3 1044.0 65.9 34.1 861.0 66.5 33.5 3635.0 D. brandisii 66.4 33.6 1766.0 67.0 33.0 1044.0 66.1 33.9 861.0 66.7 33.3 3621.0 G. angustifolia 66.6 33.4 1770.0 66.7 33.3 1044.0 65.7 34.3 860.0 66.5 33.5 3661.0 B. longinternode 66.6 33.4 1764.0 66.8 33.2 1044.0 65.9 34.1 860.0 66.6 33.4 3622.0 B. lapidea 66.4 33.6 1766.0 66.8 33.2 1044.0 65.9 34.1 861.0 66.6 33.4 3586.0 O. abyssinica (Eth_LB) 66.5 33.5 1766.0 66.8 33.2 1044.0 65.8 34.2 859.0 66.5 33.5 3661.0 P. nigra (Pks_BB) 66.2 33.8 1775.0 66.5 33.5 1001.0 65.8 34.2 860.0 66.3 33.7 3629.0 B. chungii (Pks_WB) 66.1 33.9 1766.0 66.9 33.1 985.0 65.7 34.3 861.0 66.3 33.7 3609.0 Average 66.4 33.6 1767.0 66.6 33. 4 1040.7 65.9 34.1 858.5 66.49 33.51 3612.58
30
3.2.2. Phylogenetic Inference and Relationship
3.2.2.1.Maximum Parsimony Method Phylogenetics Tree Construction
The evolutionary history was inferred using the Maximum Parsimony method. Tree #1 out of 8 most parsimonious trees (length = 144) is shown (figure 3-1). The consistency index is (0.674), the retention index is (0.854), and the composite index is 0.682 (0.576) for all sites and parsimony-informative sites (in parentheses). Ethiopian lowland bamboo ( O. abyssinica ) clustered with B. lapidea and B. longinternode with tree suppor of 80%.
Highland bamboo ( A. alpina ) observed to cluster with P. pubescence and P. edulis (known as Chinese moso bamboo) with 56% support and with G. atter 99% support.
71 B. vulgaris (Green) B. multiplex B. emeiensis (NC 015830.1) 84 B. oldhamii (NC 012927.1) B. multiplex (NC 024668.1) G. angustifolia G. sumatra (Green) D. laosenesis B. arnhemica (NC 026958.1) B. vulgaris var. striata (Yellow) 62 B. oldhamii G. sumatra (Black) B. bambos BI-1 (NC 026957.1) O. abyssinica 80 B. longinternode 81 B. lapidea B. polymorpha G. ampelxifolia 100 G. angustifolia (NC 029749.1) D. latiflorus D. diannanesis D. barbatus 51 D. brandisii P. dulcis D. sinicus D. gigantus D. membranaceus D. latiflorus (NC 013088.1) D. hamilitonis Neohouzeaua sp. (NC 026963.1) G. apus D. fuminesis 77 D. asper B. tulda A. alpina 56 P. pubescens 99 P. edulis (NC 015817.1) 76 G. atter P. nigra-(Pks-02) 99 B. chungii-(Pks-01) Figure 3-1: MP revealed genomic relationships among 31 taxa of Bambusoideae along with reference sequences (with accession numbers starting from “NC”) from NCBI using matK, ndhF and rps16 genes of cpDNA. The indigenous bamboo species are written in red font color and pointed with arrow. 31
3.2.2.2.Maximum Likelihood Method Phylogenetics Tree Construction
The evolutionary history was inferred by using the Maximum Likelihood method based on the Tamura-Nei model (Tamura and Nei 1993). The tree with the highest log likelihood (-
3448.22) is shown (figure 3-2). The percentage of trees greater than 50% in which the associated taxa clustered together is shown next to the branches. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. Except the percentage difference on tree support, ML method also provides similar result for Ethiopian bamboos.
61 B. vulgaris (Green) B. multiplex 78 B. multiplex (NC 024668.1) B. emeiensis (NC 015830.1) B. oldhamii (NC 012927.1) B. bambos BI-1 (NC 026957.1) O. abyssinica 64 B. lapidea 76 B. longinternode B. polymorpha D. laosenesis G. sumatra (Green) G. sumatra (Black) B. oldhamii B. vulgaris var, striata (Yellow) B. arnhemica (NC 026958.1) G. angustifolia B. tulda 100 G. ampelxifolia 63 G. angustifolia (NC 029749.1) D. brandisii D. barbatus D. diannanesis 68 D. fuminesis D. asper D. gigantus D. membranaceus D. sinicus P. dulcis D. latiflorus G. apus Neohouzeaua sp. (NC 026963.1) D. hamilitonis D. latiflorus (NC 013088.1) B. chungii-(Pks-02) P. nigra-(Pks-01) 99 G. atter 81 A. alpina 99 P. pubescens 61 P. edulis (NC 015817.1)
0.002 Figure 3-2: ML revealed genomic relationships among 31 taxa of Bambusoideae along with reference sequences using matK , ndhF and rps16 genes of cpDNA. The indigenous bamboo species are written in red font color and pointed with arrow.
32
3.2.2.3.Neighbor-Joining Method Phylogenetics Tree Construction
The evolutionary history was inferred using the Neighbor-Joining method (Saitou & Nei,
1987). Each cpDNA genes were analyzed to see their effectiveness in phylogenetics study of 31 taxa of woody bamboos (figure 3-3 to figure 3-5). According to independent cpDNA genes, matK (figure 3-3) and rps16 (figure 3-5A) genes showed better phylogenetic tree as
of the aggregate genes (figure 3-5B) than ndhF (figure 3-4A). Coding cpDNA genes ( ndhF together with matK ) mixed different taxa in different positions but non-coding region rps16 alone shows a better result than the coding and similar phylogenetic tree with the cumulative cpDNA genes.
For the cumulative cpDNA genes, the optimal tree with the sum of branch length = 0.079 is shown (Figure 3-5B). The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (1000 replicates) are shown next to the branches
(Felsenstein, 1985). The tree is drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree.
Again, like the result of MP and ML, NJ also shows Ethiopian lowland bamboo ( O. abyssinica ) clustered with B. lapidea and B. longinternode with tree suppor of 66%.
Highland bamboo ( A. alpina ) observed to cluster with P. pubescence and P. edulis with
74% support and with G. atter 99% support.
33
B.vulgaris-(Green) 68 B. multiplex 77 B. multiplex (NC 024668.1) B. oldhamii (NC 012927.1) B. emeiensis (NC 015830.1) O. abyssinica B. longinternode 66 73 B. lapidea B. polymorpha B. bambos BI-1 (NC 026957.1) D. laosenesis G. sumatra-(Green) G. sumatra (Black) B. oldhamii B. vulgaris-striata-(Yellow) G. angustifolia B. arnhemica (NC 026958.1) B. tulda D. barbatus D. gigantus D. diannanesis 68 D. fuminesis D. asper Neohouzeaua sp. (NC 026963.1) G. apus P. dulcis D. hamilitonis D. latiflorus D. membranaceus D. sinicus D. latiflorus (NC 013088.1) B. chungii-(Pks-02) P. nigra-(Pks-01) 99 G. atter 67 A. alpina 99 P. pubescens 74 82 P. edulis (NC 015817.1) D. brandisii G. ampelxifolia 100 G. angustifolia (NC 029749.1)
0.002 Figure 3-3: NJ revealed genomic relationships among 31 taxa of Bambusoideae along with reference sequences using matK gene of cpDNA. The indigenous bamboo species are written in red font color and pointed with arrow.
34
B. tulda 100 G. ampelxifolia Neohouzeaua sp. (NC 026963.1) 99 G. angustifolia (NC 029749.1) D. hamilitonis 70 D. brandisii D. gigantus 33 G. angustifolia D. asper O. abyssinica D. fuminesis B. longinternode 3199 D. barbatus 79 B. lapidea P. dulcis D. laosenesis G. apus G. sumatra-(Green) D. latiflorus 37 B. oldhamii D. membranaceus 16 G. sumatra (Black) D. diannanesis 30 B. vulgaris-striata-(Yellow) D. latiflorus (NC 013088.1) B. arnhemica (NC 026958.1) D. sinicus B. polymorpha B. polymorpha B. bambos BI-1 (NC 026957.1) B. emeiensis (NC 015830.1) B. bambos BI-1 (NC 026957.1) 9052 B.vulgaris-(Green) B.vulgaris-(Green) 72 B. emeiensis (NC 015830.1) B. oldhamii (NC 012927.1) 42 B. multiplex 100 P. nigra-(Pks-01) 40 B. chungii-(Pks-02) 54 B. multiplex (NC 024668.1) B. multiplex B. tulda B. oldhamii (NC 012927.1) D. barbatus B. multiplex (NC 024668.1) 62 D. fuminesis 62 B. lapidea D. asper 94 O. abyssinica D. gigantus 51 B. longinternode Neohouzeaua sp. (NC 026963.1) 98 B. oldhamii D. hamilitonis D. sinicus G. sumatra (Black) 40 G. sumatra-(Green) G. apus D. laosenesis P. dulcis B. vulgaris-striata-(Yellow) D. latiflorus B. arnhemica (NC 026958.1) D. membranaceus G. angustifolia 64 D. diannanesis G. ampelxifolia D. latiflorus (NC 013088.1) 100 74 D. brandisii P. nigra-(Pks-01) 100 B. chungii-(Pks-02) 76 G. angustifolia (NC 029749.1) G. atter A. alpina G. atter P. pubescens 100 P. pubescens 96 P. edulis (NC 015817.1) 68 P. edulis (NC 015817.1) A. alpina 96 A B 0.05 0.0100 Figure 3-4: NJ revealed genomic relationships among 31 taxa of Bambusoideae along with reference sequences using (A) ndhF and (B) ndhF plus matK genes of cpDNA. The indigenous bamboo species are written in red font color and pointed with arrow.
35
B. tulda 74 B. lapidea Neohouzeaua sp. (NC 026963.1) 66 B. longinternode D. sinicus O. abyssinica D. hamilitonis B. bambos BI-1 (NC 026957.1) D. gigantus B. polymorpha D. fuminesis B. emeiensis (NC 015830.1) D. barbatus B. oldhamii (NC 012927.1) D. membranaceus 77 B. multiplex (NC 024668.1) D. latiflorus 72 B. vulgaris (Green) D. diannanesis 59 B. multiplex D. asper D. laosenesis D. latiflorus (NC 013088.1) G. sumatra (Green) G. apus G. sumatra (Black) 64 P. dulcis B. oldhamii B. longinternode B. vulgaris var. striata (Yellow) B. lapidea B. arnhemica (NC 026958.1) O. abyssinica G. angustifolia P. nigra-(Pks-01) B. tulda B. arnhemica (NC 026958.1) D. barbatus B. chungii-(Pks-02) D. gigantus B. vulgaris-striata-(Yellow) D. diannanesis D. laosenesis 62 D. fuminesis B. oldhamii D. asper G. sumatra-(Green) D. membranaceus G. sumatra (Black) Neohouzeaua sp. (NC 026963.1) B. polymorpha D. hamilitonis 63 B.bambos BI-1 (NC 026957.1) P. dulcis B. emeiensis (NC 015830.1) D. latiflorus B.vulgaris-(Green) G. apus B. multiplex 99 D. latiflorus (NC 013088.1) B. multiplex (NC 024668.1) D. sinicus B. oldhamii (NC 012927.1) D. brandisii G. angustifolia G. ampelxifolia G. ampelxifolia 60 100 G. angustifolia (NC 029749.1) D. brandisii 100 99 G. atter 75 G. angustifolia (NC 029749.1) A. alpina A. alpina 66 74 P. pubescens G. atter P. edulis (NC 015817.1) P. pubescens 82 65 99 P. nigra-(Pks-01) P. edulis (NC 015817.1) B. chungii-(Pks-02)
0.002 0.002 Figure 3-5: NJ revealed genomic relationships among 31 taxa of Bambusoideae along with reference sequences using (A) rps16 and (B) cumulative of matK , ndhF and rps16 genes of cpDNA. NB: - The indigenous bamboo species are written in red font color and pointed with arrow.
36
O.abyssinica-(BGK-Yass) 50 O.abyssinica-(BGK-Kema) O.abyssinica-(BGA-Kurm) 56 B. lapidea O.abyssinica-(ORWW-Gimb) B. longinternode O.abyssinica-(SNNPs-Kont) O.abyssinica-(ORBB-DabuH) Oxytenathera 59 O.abyssinica-(BGM-Dang) 56 O.abyssinica-(BGM-Mand) O.abyssinica-(BGM-Pawe) O. abyssinica O.abyssinica-(BGA-Asso) O.abyssinica-(BGM-Guba) O.abyssinica-(BGA-Bamb) B. polymorpha Bambuseae B. bambos BI-1 (NC 026957.1) B. oldhamii (NC 012927.1) B. emeiensis (NC 015830.1) 80 B. multiplex (NC 024668.1) Bambusa B. vulgaris (Green) 68 57 B. multiplex G. angustifolia D. laosenesis (I) G. sumatra (Green) B. vulgaris (Yellow) B. oldhamii Bambusa B. arnhemica (NC 026958.1) G. sumatra (Black) O. abyssinica-(GAM-Abol) D. latiflorus (NC 013088.1) D. dianxiensis D. sinicus Neohouzeaua sp. (NC 026963.1) G. apus D. hamilitonis D. membranaceus Dendrocalamus D. latiflorus D. fuminesis Bambuseae 62 D. asper P. dulcis D. gigantus D. barbatus D. brandisii G. angustifolia (NC 029749.1) 64 Guadua 100 G. ampelxifolia B. tulda B. chungii-(Pks-02) P. nigra-(Pks-01) 99 77 A. alpina 65 P. edulis (NC 015817.1) Phyllostachys (II) 87 P. pubescens 99 G. atter
0.002 Figure 3-6: NJ revealed genomic relationships among 31 taxa of Bambusoideae along with reference sequences and Ethiopian lowland bamboo ( O. abyssinica ) using matK , ndhF and rps16 genes of cpDNA (I) - Bambusoideae (tropical woody bamboo) and (II) - Arundinareae (temperate woody bamboo). 37
Table 3-3: List of bamboo species and an accurate and complete GenBank record and/or accession numbers at NCBI Origin Accession Numbers of Genes S. Source of Coding Region Intron No. Species Name Genus Subtribe Tribe Origin matK ndhF rps16 1. Gigantochloa_sumatra_(Black) Unclassified Unclassified Introduced 2. Dendrocalamus_latiflorus Dendrocalamus Bambusinae Bambuseae Introduced MT476656 MH72 7666 MT123879 3. Guadua_amplexifolia Phyllostachys Arundinariinae Arundinarieae Introduced 4. Gigantochloa_apus Gigantochloa Bambusinae Bambuseae Introduced MT47665 7 MH727667 MT123876 5. Phyllostachus_dulcis Phyllostachys Arundinariinae Arundinarieae Introduced 6. Gigantochloa_atter Gigantochloa Bambusinae Bambuseae Introduced MT47665 8 MH727668 MT123877 7. Dendrocalamus_barbatus Dendrocalamus Bambusinae Bambuseae Introduced MT476659 MH727669 MT123875 8. Bambusa_polymorpha Bambusa Bambusinae Bambuseae Introd uced MT476660 MH727670 MT123878 9. Dendrocalamus_dianxiensis Unclassified Unclassified Introduced 10. Dendrocalamus_fuminesis Dendrocalamus Bambusinae Bambuseae Introduced 11. Dendrocalamus_asper Dendrocalamus Bambusinae Bambuseae Introduced MT476661 MH7 27671 MT123880 12. Bambusa_vulgaris _(Green) Bambusa Bambusinae Bambuseae Introduced MT476662 MH727672 MT123881 13. Phyllostachus_pubescens Phyllostachys Arundinariinae Arundinarieae Introduced 14. Gigantochloa_sumatra_(Green) Unclassified Unclassified Introduced 15. Bambusa_oldhamii Bambusa Bambusinae Bambuseae Introduced MT4766 63 MH727673 MT123882 16. Dendrocalamus_gigantus Dendrocalamus Bambusinae Bambuseae Introduced 17. Bambusa_multiplex Bambusa Bambusinae Bambuseae Introduced MH727674 MT123883 18. Dendro calamus_hamilitonis Dendrocalamus Bambusinae Bambuseae Introduced 19. Arundinaria_alpina Oldeania Arundinariinae Arundinarieae Ethiopia MT476664 MH727675 MT123884 20. Dendrocalamus_sinicus Dendrocalamus Bambusinae Bambuseae Introduced MT476665 MH727676 MT12 3885 21. Dendrocalamus_membranaceus_Cx_Grandis Dendrocalamus Bambusinae Bambuseae Introduced MT476666 MH727677 MT123886 22. Dendrocalamus_laosenesis Unclassified Unclassified Introduced 23. Bambusa vulgaris var. striata (Yellow) Bambusa Bambusinae Bambuseae Introduced MT476667 MH727678 MT123887 24. Bambusa_tulda Bambusa Bambusinae Bambuseae Introduced MT476668 MH727679 MT123888 25. Dendrocalamus_brandisii Dendrocalamus Bambusinae Bambuseae Introduced MT476669 MH727680 MT123889 26. Guadua_angustifolia Guadua Guaduin ae Bambuseae Introduced MH727681 MT123891 27. Bambusa_longinternode Unclassified Unclassified Introduced 28. Bambusa_lapidea Bambusa Bambusinae Bambuseae Introduced MT476670 MH727682 MT123890 29. Oxytenanthera_abyssinica Oxytenanthera Bambusinae Bambuseae Ethiopia MT476671 MH727683 MT123892 30. Phyllostachys_nigra (black bamboo) Phyllostachys Arundinariinae Arundinarieae Pakistan MT476672 MH727684 MT123894 31. Bambusa_chungii (white bamboo) Bambusa Bambusinae Bambuseae Pakistan MT476673 MH727685 MT123893
38
3.3. Discussion
The taxonomy of bamboo has puzzled researchers because of bamboo reproductive characteristics. Some of the same accessions may have different names, while some different accessions may have the same name (Zhao et al., 2015). Bamboos have long been a problematic plant group to examine with molecular phylogenetic techniques. Rare heterogeneity among lineages, lack of sequence variation in certain genera and subtribes, and short internodes deep within the topology have prevented consistent and well supported resolution of branching order among and within major bamboo clades (Kelchner and BPG, 2013). With the fast development of molecular biology, the molecular marker of bamboo was developed and used for bamboo genetic diversity and phylogenetic analysis which was helpful for its taxonomy.
Many plant phylogenetic studies are based on cpDNA. In plants, cpDNA is smallest as compared to mitochondria and nuclear genome. It is assumed to be conserved in its evolution in terms of nucleotide substitution with very little rearrangements that permit the molecule to be used in resolving phylogenetic relationships especially at deep levels of evolution. Simple genetics property, a high copy within typical genomic DNA, and structural stability make cpDNA preferable for evolutionary studies in many plants (Small et al., 2004). The chloroplast genome can be divided into three functional categories including (1) protein-coding genes, (2) introns, and (3) intergenic spacers; the latter two do not encode proteins and are referred to as non-coding regions. According to the Nicotiana
chloroplast map, approximately 43% of the large single-copy (LSC) and small single-copy
39
(SSC) are noncoding. Fifteen introns make up approximately 10.6% of the single-copy chloroplast DNA, while 92 intergenic spacers comprise 32.3% (Shaw et al., 2007).
This study provides the first information about cpDNA based phylogenetics study of introduced bamboo species over the indigenous Ethiopian bamboos. The molecular topologies recovered in this study provide a number of valuable insights into bamboo evolution and the phylogenetic similarities to Ethiopian and Pakistani woody bamboos.
Among these, several observations can be noted regarding the closest relatives of temperate woody bamboos and tropical woody bamboos (Mukherjee et al., 2010; Kelchner and BPG,
2013; Wu et al., 2015).
Mostly Ethiopian lowland bamboo ( O. abyssinica ) was clustered with Bambusa and
highland bamboo ( A. alpine) was clustered with Phyllostachys and Pakistani woody bamboos P. nigra and B. chungii with Phyllostachys . Clustering of Ethiopian lowland bamboo ( O. abyssinica ) with Bambusa , highland bamboo ( A. alpine) with Phyllostachys and Pakistani woody bamboos P. nigra with Phyllostachys was as of expected and similar to the work of others that temperate woody bamboos clustered with temperate woody bamboos and evolved prior than tropical woody bamboo (Sungkaew et al., 2009;
Bouchenak-Khelladi et al., 2010; Mukherjee et al., 2010; Triplett and Clark, 2010;
Kelchner and BPG, 2013). Kelchner and BPG (2013) using five plastid DNA regions (one gene (ndhF), two group II introns (rpl16 intron, rps16 intron), and two intergenic spacers
(trnD–trnT, trnT–trnL)) have found that O. abyssinica was clustered with B. vulgaris in paleotropical woody bamboo group. But clustering of B. chungii in a genus of Bambusa
40
(tropical woody bamboo) with Phyllostachys and Guadua (both of them are grouped under
temperate woody bamboo) is uncommon and might be sampling error and needs further
detail assessment.
The three cpDNA genes ( matK , ndhF , and rps16 ) were analyzed separately and then
combined into a single data to construct an optimal NJ tree (Figure 4-4 A-D). The matK
and rps16 genes of the cpDNA showed the result similar with the result of the aggregate
cpDNA genes.
Except difference on percentage of tree support, both tree construction methods showed
that, Ethiopian lowland bamboo ( O. abyssinica ) clustered with B. lapidea and B. longinternode with tree support of 80% in MP, 76% in ML and 73% in NJ. Highland bamboo ( A. alpina ) observed to cluster with P. pubescence and P. edulis (known as
Chinese moso bamboo) with 56% support in MP, 61% in ML and 74 % in NJ methods.
A novel result of the present study is, from the overall cpDNA genes based dendrogram
result of 31 taxa and thirteen Ethiopian lowland bamboo populations (figure 3-6). Ethiopian
lowland bamboo ( O. abyssinica ) collected from Gambella region associated differently
than other lowland bamboo ( O. abyssinica ) samples and mostly it is associating with
Bambusa and Gigantochloa . Even it showed morphological variation from others (personal
observation). The leaves were broad and dark green, the culm looks taller and wider in
diameter. This implies samples collected from Gambella region are different from others
and might tell us there might be additional bamboo species in the country or introduced a
long time ago even though there is no evidence. 41
CHAPTER FOUR
4. Genetic Diversity, Population Structure and Gene Flow Analysis of
Ethiopian Lowland Bamboo [Bambusinea: Oxytenanthera abyssinica (A.
Rich.) Munro] Using cpDNA Genes Sequences
4.1. Materials and Methods
Three to five young fresh leaves were immersed in 15ml falcon tube containing 2% CTAB
solution. CTAB solution immersed young fresh leaves of three individual plants of
Ethiopian lowland bamboo ( O. abyssinica ) from thirteen potential bamboo growing areas
across the country were collected for the study. GPS data and altitudinal information for
each sample were also collected and presented in table 4-1. Maps showing sample coverage
and collection sites are described in figure 4-1.
Table 4-1: Samples information along with their GPS location Specific collection GPS Reading Altitude Region Zone District site X Y m.a.s.l Guba Yarenja 11 o 16 ' 13.1 " 035 o 22 ' 15.4 " 824 Dangur Misreta 11 o 18 ' 50.3 " 036 14 ' 10.6 " 1240 Metekel Mandura Et sitsa 11 o 09 ' 14.5 " 036 o 19 ' 50.3 " 1039 Pawe/Almu Mender 30 11 o 18 ' 32.5 " 036 o 24 ' 40.2 " 1118 Benishangul- Bambasi Ambesa Chaka 09 o 53 '55.0 " 034 o 40 ' 01.8 " 1518 Gumuz Assosa Assosa Tsetse Adurnunu 10 o 09 ' 29.9 " 034 o 31 ' 37.1 " 1507 Kurmuk HorAz ab 10 o 32 ' 33.7 " 034 o 28 ' 57.9 " 1275 Kemash Kemash 09 o 29 ' 31.4 " 035 o 52 ' 35.2 " 1234 Kemash Yasso Dangacho 09 o 52 ' 27.5 " 036 o 05 ' 32.6 " 1176 West Wollega Gimbi Aba Sena Forest 09 o 01' 32.2" 035 o 59' 54.1" 1407 Oromia BunoBedele DabuHena Did hessa Valley 08 o 40 ' 21.1 " 036 o 23 ' 32.9 " 1399 Gambella Gambella Abol Penkwe 08 o 14 ' 13.1 " 034 o 31 ' 06.2 " 435 SNNPs Konta Konta Koyshe 06 o 43 ' 35.6 " 036 o 34 ' 26.8 " 958
42
A B
C
Figure 4-1: (A) Bamboo cover map of Ethiopia (Zhao et al., 2018), (B) Map of Ethiopia with sample collection area and (C) Map of the sample collection area
43
4.1.1. DNA Extraction and PCR amplification
Three independent leaf materials from thirteen populations were used for DNA isolation.
DNA was isolated separately using a modified CTAB DNA isolation method (Hyder et al.,
2007) at BMBB laboratory, Department of Biosciences, CUI, Pakistan. Test gel electrophoresis in 1% agarose and nanodrop (Implen Nanophotometer 190-1100nm spectrophotometer) of each sample was used to measure DNA quantity and quality. Those with high DNA quantity and quality were used for PCR amplification. Among 10 primers that amplify 10 specific cpDNA regions selected from Chokthaweepanich (2014) and
Attigala (2015) and designed via Primer3 ( http://bioinfo.ut.ee/primer3-0.4.0/ ) primer
designing program, three chloroplast sequences with coding ( matK and ndhF ) and non-
coding ( rps16 intron) were used (Table 3-1).
4.1.2. PCR product profiling, sequencing, and alignment
PCR reaction (50µl per reaction) and amplification contained 7.50µl of 50 - 100ng/µl
template DNA, 5.0µl of Taq buffer (100mM Tris-HCl, 500mM KCl, 15mM MgCl 2, pH
8.5 (25 0C), 5.0µl of dNTPs mix (2.5mM each), 2.5µl of Taq DNA Polymerase (5U/µl)
(WizPure™ Taq DNA Polymerase), 1.25µl of 25pM of each primer (Table 2) and 28.75µl
of PCR grade H 2O. Profile of PCR for all primer sets included pre-PCR denaturation at 96
°C for 3 minutes followed by 35 cycles of denaturing at 96 °C for 30 seconds, annealing at
53 °C for 30 seconds, extension at 72 °C for 1 minute, a final extension at 72 °C for 20
minutes and hold at 4 °C. 3.0µl PCR products were analyzed using a standard 1% agarose
gel electrophoresis and purified and paired-end sequenced at Macrogen, Inc. Seoul, Korea.
44
The sequence of both strands of every fragment amplified from each sample was assembled separately using DNA Dragon version 1.6.0 and each sampling district was represented by a single sequence with the one very identical and informative among the triplicate samples.
The assembled sample was submitted to the GenBank and used for sequence analysis.
BLAST searches for each target sequence were used to confirm probable homology (Query cover, Identity percentage, E-value and Direction of the strand).
Sequences of three markers from thirteen O. abyssinica cpDNA were arranged in FASTA
format and aligned in MAFFT (multiple sequence alignment software version 7) (Katoh &
Standley, 2013) and realigned again using MUSCLE of MEGA version 7.0 (Kumar et al.,
2016) to increase the quality of final alignment product. Sequence information for
submission to NCBI was prepared by Sequin v5.51. An accurate and complete GenBank
record or accession number is reported in Table 4-3.
4.1.3. Evolutionary tree construction and network analysis
The three markers ( matK , ndhF and rps16 ) were analyzed separately and then combined
into a single data set. The sequence alignments with MUSCLE were used to identify the best nucleotide substitution model and construct the MP tree (Figure 4-2) and NJ tree
(Figure 4-3) using MEGA version 7.0 (Tamura et al., 2013). The MP tree was acquired using the search level 1 Subtree-Pruning-Regrafting (SPR) algorithm (Nei & Kumar, 2000)
(Nei and Kumar 2000) in which the initial trees were obtained by adding sequences in random (10 replicates). The tree is drawn to scale, with branch lengths calculated using the average pathway technique and in the number of change units throughout the sequence.
45
Bootstrap analysis with a thousand replicates was used to estimate nodal support. On the other hand, NJ tree (Figure 3) analysis was conducted using the Kimura’s two-parameter distance correction mode to build a phylogenetic tree.
The evolutionary distances were calculated based on MCL method (Tamura & Nei, 1993)
(Tamura and Nei 1993) and are in the units of the number of base substitutions per site.
Gamma distribution (shape parameter = 1) was used for the rate variation among sites.
Thirteen nucleotide sequences were involved in the analysis. For each sequence pair, all ambiguous positions have been removed and for the final dataset, there were a total of
3,694 positions.
DnaSP version 6.10.01 was used to generate haplotype files (with and without the use of the indels). The generated sequence files saved as Roehl format and network analyses were performed via Network version 5.0.1.1 (http://www.fluxus-engineering.com/sharenet.htm ).
4.1.4. Measuring nucleotide diversity, InDel polymorphism, and gene low and
genetic differentiation
DnaSP version 6.10.01 were used to calculate and analyze (1) nucleotide diversity including an average number of nucleotides difference (k), nucleotides diversity (π), population mutation rates per 100 sites (θw) for total sequence (coding + non-coding regions together) and coding and non-coding regions separately, (2) InDel polymorphism including number of sites with fixed gaps, total number of (InDel and non-InDel) sites, average InDel length, InDel diversity k(i) and InDel diversity per sites π(i), and (3) gene
46 flow and genetic differentiation including Gene flow via genetic differences among population (Gamma St) and average level of gene flow (Fst) and genetic differentiation via nucleotide sequence-based statistics (Ks) and average number of nucleotide differences between population 1 and population 2 (Kxy).
4.2. Results
There were 13 nucleotide sequences involved in the analysis of the current study. For each pair of sequences, each ambiguous position was removed and in the last dataset, there was an aggregate of 3,694 positions. Evolutionary history using MP and NJ together with nucleotide diversity analysis, DNA divergence between populations, InDel polymorphism and gene flow and genetic differentiation analysis on Ethiopian lowland bamboo ( O.
abyssinica ) were investigated to analyze on this part which is the first to study the plants
genetic diversity, population structure and gene flow using coding (matK and ndhF ) and
non-coding ( rps16 ) regions of cpDNA genes. Accession number for matk , ndhF and rps16
obtained from NCBI presented on table 4-2.
Table 4-2: An accurate and complete GenBank record (accession numbers at NCBI). Sample Coding Region Intron No. Collection Area Name matK ndhF rps16 1. BG_Asso_Bambasi Bambasi MH445413 MH445426 MH445439 2. BG_Asso_Assosa Assosa MH445414 MH445427 MH445440 3. BG_Asso_K urmuk Kurmuk MH445415 MH445428 MH445441 4. BG_Metk_Guba Guba MH445416 MH445429 MH445442 5. BG_Metk_Dangur Dangur MH445417 MH445430 MH445443 6. BG_Metk_Mandura Mandura MH445418 MH445431 MH445444 7. BG_Metk_Pawe/Almu Pawe MH445419 MH445432 MH445445 8. BG_Kem_Kema sh Kemash MH445420 MH445433 MH445446 9. BG_Kem_Yasso Yasso MH445421 MH445434 MH445447 10. OR_W/Wollg_Gimbi Gimbi MH445422 MH445435 MH445448 11. OR_B/Bed_Dabu Hena Dedhesa MH445423 MH445436 MH445449 12. GM_Gamb_Abol Abol MH445424 MH445437 MH445450 13. SNNPs_Kon_Kont a Koyshe MH445425 MH445438 MH445451 47
4.2.1. Chloroplast DNA sequence character and sequence divergence
GC and AT content of each and aggregate cpDNA genes were analyzed (table 4-4). Highest AT content (66.6) in Bambasi, Kurmuk and
Pawe populations and least (66.4) in Dangur, Abol and Dabu Hena populations was observed by the aggregate genes while the GC content was highest (33.6) in Dangur, Abol and Dabu Hena populations and the least (33.4) was observed in Bambasi, Kurmuk and
Pawe populations. Average GC and AT content and total sequence was observed (66.5, 33.5 and 3658.6) in the aggregate cpDNA genes respectively. Since the comparison was between different populations of a single species ( O. abyssinica ), there was no significant difference on GC and AT content observed and the result of each samples were close to the average.
Table 4-3: GC and AT content of each and aggregate cpDNA genes. matK (~ 1,350 bp) ndhF (~ 1,140 bp) rps16 (~ 860 bp) Aggregate genes Name of the species Percentage Total Percentage Total Percentage Total Percentage Total AT GC Sequence AT GC Sequence AT GC Sequence AT GC Sequence O. abyssinica -(BGA-Asso) 66.4 33.6 1778.0 66.8 33.2 1057.0 65.9 34.1 848.0 66.5 33.5 3670.0 O. abyssinica -(BAB-Bamb) 66.4 33.6 1778.0 66.7 33.3 1057.0 66.0 34.0 853.0 66.6 33.4 3666.0 O. abyssinica -(BGA-Kurm) 66.4 33.6 1778.0 66.8 33.2 1057.0 66.2 33.8 852.0 66.6 33.4 3669.0 O. abyssinica -(BKK-Kema) 66.4 33.6 1778.0 66.6 33.4 1057.0 66.2 33.8 852.0 66.5 33.5 3662.0 O. abyssinica -(BGK-Yass) 66.4 33.6 1778.0 66.6 33.4 1057.0 66.2 33.8 852.0 66.5 33.5 3656.0 O. abyssinica -(BGM-Dang) 66.4 33.6 1779.0 66.4 33.6 1057.0 66.1 33.9 852.0 66.4 33.6 3680.0 O. abyssinica -(BGM-Guba) 66.4 33.6 1778.0 66.7 33.3 1056.0 66.2 33.8 852.0 66.5 33.5 3634.0 O. abyssinica -(BGM-Mand) 66.4 33.6 1779.0 66.6 33.4 1056.0 66.2 33.8 852.0 66.5 33.5 3635.0 O. abyssinica -(BGM-Pawe) 66.4 33.6 1779.0 66.4 33.6 1057.0 66.1 33.9 852.0 66.6 33.4 3648.0 O. abyssinica -(GAM-Abol) 66.4 33.6 1778.0 66.5 33.5 1058.0 66.0 34.0 852.0 66.4 33.6 3671.0 O. abyssinica -(ORWW-Gimb) 66.3 33.7 1779.0 66.8 33.2 1057.0 66.2 33.8 852.0 66.5 33.5 3648.0 O. abyssinica -(ORBB-DabuH) 66.4 33.6 1779.0 66.4 33.6 1057.0 66.1 33.9 852.0 66.4 33.6 3650.0 O. abyssini ca -(SNNPs-Koys) 66.5 33.5 1778.0 66.4 33.6 1057.0 66.1 33.9 853.0 66.5 33.5 3673.0 Average 66.4 33.6 1778.4 66.6 33.4 1056.9 66.1 33.9 851.8 66.5 33.5 3658.6
48
4.2.2. Phylogenetic inference and relationship
4.2.2.1.Maximum parsimony method evolutionary history analysis The evolutionary history of bamboos was inferred using the MP method. The analysis showed consistency index (0.800), composite index 0.824 (0.706) and retention index
(0.882) for all sites and parsimony-informative sites (in parentheses) (Figure 4-2). The percentage of replicate trees in the bootstrap test (Felsenstein, 1985) (Felsenstein 1985) grouped together by the associated taxa 1000 replicates is shown next to the branches.
Distant populations (SNNPs + Gambella) showed distinctly different from other populations but others showed intermixing up between populations.
Abol Koyshe 95 Mandura 55 Guba 96 Bambasi Assoaa Kurmuk 38 Gimbi 53 Yasso 57 20 85 Kemash 62 Dangur Dabu Hena 77 Pawe
2.5 Figure 4-2: The Maximum Parsimony tree of O. abyssinica obtained based on pair-wise distance from the combined data of matK, ndhF and rps16.
4.2.2.2.Neighbor-Joining method evolutionary history analysis The evolutionary history of bamboos was inferred based on the Neighbor-Joining method
(Saitou & Nei, 1987) (Saitou and Nei 1987). NJ showed the optimal tree with the total
length of the branch = 0.012 (Figure 4-3). Except samples collected from Oromia region
that showed mixing with other groups, other populations form their own group which
secured the distinctness of their population and effectiveness of genes used for sequencing.
49
46 Assosa Assosa Zone Bambasi 54 Kurmuk Assosa Zone
67 Yasso 43 Kemash Zone 63 Kemash
55 Gimbi West Wollega
Guba
59 Mandura Metekel Zone
32 Pawe
Dangur Metekel Zone
79 Dabu Hena Buno Bedelle
Koyshe SNNPs Distant Population 45 Abol Gambella
0.0019 Scale Figure 4-3: The neighbor joining tree of O. abyssinica obtained based on pair-wise distance from the combined data of matK, ndhF and rps16.
The three cpDNA genes ( matK , ndhF 3', and rps16 ) were analyzed separately and then
combined into a single data to construct an optimal NJ tree (Figure 4-4 A-D). The sum of branch length (A) = 0.003, (B) = 0.011, (C) = 0.007 and (D) = 0.006 was obtained. There
was a total of (A) = 1,771, (B) = 1,001, (C) = 834 and (D) = 2,773 positions in the final
dataset. The ndhF 3' end of the cpDNA gene alone showed the result similar with all primers merged together. Three major clusters and three sub-clusters with five clades
(Assosa Zone, Kemash Zone, Metekel Zone, the distant and the intermixed Oromia region
samples) were formed in the final NJ analysis. In all condition’s samples collected from
Kemash Zone is not separated and always clustered together with great nodal support and
this population shows lastly evolved.
50
Koyshe 86 Guba 65 Dabu Hena 17 Mandura Dangur Gimbi 9 Mandura Assosa Bambasi 22 Kemash Guba B 64 Yasso A 94 Kurmuk Kurmuk Kemash 39 Bambasi 59 Yasso Dangur Gimbi Pawe 65 Assosa Dabu Hena Pawe Abol Abol Koyshe
0.000100 0.00050
48 Gimbi 44 Dabu Hena Kemash 52 Yasso Dangur Pawe C Kurmuk Bambasi Assosa Mandura Guba Koyshe Abol 0.00050 Figure 4-4: The NJ tree obtained based on pair-wise distance from each genes A. matK , B. ndhF , and C. rps16 gene.
4.2.3. Network Analysis
Total number of mutations disregarding the torso (130, 27), estimated number of mutations
of shortest tree within the torso (73, 0), estimated number of mutations of shortest tree
(203, 27), total number of taxa (13, 13) and total number of haplotypes (13, 11) were
observed on gaps or missing data considered and not considered network analysis. Number
values before parenthesis are for gaps or missing data considered and after parenthesis for
gaps or missing data not considered. Haplotype 8 (Kurmuk sample of Assosa Zone) from
gaps or missing data considered (Figure 4A) and haplotype 2 (Bambasi sample of Assosa
Zone) from gaps or missing data not-considered (Figure 4B) has descendants around them,
51 many of which differ from them by nucleotide change (at sites shown by numbers), some are more distantly related. Both forms approve that; Assosa Zone is the root of O.
abyssinica and others have diverged from this Zone. The distant populations H_3 (Abol
sample of Gambella Region) and H_11 (Koyshe sample of SNNPs Region) from gaps or
missing data not-considered and H_3 (Abol sample of Gambella Region) and H_13
(Koyshe sample of SNNPs Region) from gaps or missing data considered showed distant
from the root.
A B
Figure 4-5: Haplotype network of the combined cpDNA region obtained based on (A) gaps/missing data considered and (B) gaps/missing data not-considered. Note 1: Haplotypes for figure 5A; H_1 [Assosa], H_2 [Bambasi], H_3 [Abol], H_4 [Kemash], H_5 [Yasso], H_6 [Dangur], H_7 [Pawe], H_8 [Kurmuk], H_9 [Guba], H_10 [Guba], H_11 [Mandura], H_12 [Dabu Hena] and H_13 [Gimbi]. Note 2: Haplotypes for figure 5B; H_1 [Assosa], H_2 [Bambasi], H_3 [Abol], H_4 [Kemash + Yasso], H_5 [Dangur + Dabu Hena], H_6 [Pawe], H_7 [Kurmuk], H_8 [Guba], H_9 [Mandura], H_10 [Gimbi] and H_11 [Koyshe].
52
4.2.4. Nucleotide Diversity Analysis
Metekel Zone found extremely higher k (23.167), π (0.00633 ± 0.00046) and θw (22.33333 ± 0.00099). Distant populations (11.000,
0.00300 ± 0.00150, 11.00000 ± 0.00222) followed by Oromia, Assosa Zone, and Kemash Zone were found to be lower in k, π, and θw
(Table 4-4). This implicates that gene differentiation in Metekel Zone and the distant populations is higher and that makes them a diverse population as compared to others.
Table 4-4: Nucleotide diversity analysis on Ethiopian lowland bamboo populations in different Zones. Analysis in Pair wise Comparisons Total Coding Region Non - Coding Region Pupulation k Π θw k Π θw k π θw Assosa Zone 4.333 0.00118 ± 0.00026 4.33333 ± 0.00063 2.000 0.00071 ± 0.00025 2.00000 ± 0.00053 1.333 0.00159 ± 0.00075 1.33333 ± 0.00132 Metekel Zone 23.167 0.00633 ± 0.00046 22.33333 ± 0.00099 10.667 0.00380 ± 0.00049 10.12121 ± 0.0 0096 1.333 0.00156 ± 0.00034 1.09091 ± 0.00102 Kemash Zone 2.000 0.00055 ± 0.00027 2.00000 ± 0.00047 0.000 0.00000 ± 0.00000 0.00000 ± 0.00000 0.000 0.00000 ± 0.00000 0.00000 ± 0.00000 Oromia 8.000 0.00219 ± 0.00110 8.00000 ± 0.00165 6.000 0.00214 ± 0.0 0107 6.00000 ± 0.00163 2.000 0.00232 ± 0.00116 2.00000 ± 0.00201 Distant Pop. 11.000 0.00300 ± 0.00150 11.00000 ± 0.00222 8.000 0.00283 ± 0.00142 8.00000 ± 0.00213 2.000 0.00233 ± 0.00117 2.00000 ± 0.00202 Note: k denotes average number of nucleotide differences, π (Pi) - pair-wise average nucleotide diversity per 100 sites along with standard deviation and θw (Theta-w) signifies Watterson estimator for population mutation rates per 100 sites with its standard deviation
53
4.2.5. InDel Polymorphism Analysis
Average InDel length was higher on Kemash (15.333) and Metekel Zones (12.214) and the
lower value was observed on Assosa (7.143), distant and Oromia populations (Figure 4-6).
Whereas the total number of InDel and non-InDel sites analyzed were higher for
populations of Metekel (3,692), distant population (3,679) and Assosa Zone (3,678) but
populations from West Wellega and Buno Bedele Zones of Oromia Region and Kemash
Zone populations show relatively smaller value (Table 4-5). Higher frequency of InDel
makes Metekel, the distant population and Assosa Zone populations more diverse than
Oromia (3,654) and Kemash Zone (3,668) populations. From this, we can conclude InDel
plays a significant role in genetic differentiation and population structure of Ethiopian
lowland bamboo ( O. abyssinica ) populations.
Table 4-5: InDel polymorphism of Ethiopian lowland bamboo ( O. abyssinica ). Total Total Total Total number Number of number of number of Average number of (InDel and Collection Site sites with InDel non-InDel InDel k(i) π(i) of InDel non-InDel) fixed gaps sites sites length sites sites analysed analysed analysed Assosa Zone 16 18 3660 18 3678 7.143 4.667 0.00127 Kemash Zone 26 16 3652 16 3668 15.333 3 0.00082 Metekel Zo ne 2 75 3617 75 3692 12.214 6 0.00163 Oromia 40 8 3646 8 3654 4 2 0.00055 Distant Pop. 15 12 3667 12 3679 4.5 4 0.00109 Note: k(i) denotes InDel diversity, π(i) - InDel diversity per sites
54
InDel polymorphism of Ethiopian lowland bamboo (O. abyssinica) Frequency and Percentage
A B C 15, 15.2% 16, 16.2% 12, 9.3% 18, 14.0% 8, 6.2% 3667, 20.1% 3660, 20.1% Category 16, 12.4% Assosa Zone 26, 26.3% 3646, 20.0% 3652, 20.0% Kemash Zone 40, 40.4% Metekel Zone Oromia 2, 2.0% 75, 58.1% 3617, 19.8% Out Group D E F 12, 9.3% 18, 14.0% 3679, 20.0% 3678, 20.0% 4.500, 10.4% 7.143, 16.5% 8, 6.2% 4.000, 9.3% 16, 12.4%
3654, 19.9% 3668, 20.0% 12.214, 28.3% 15.333, 35.5%
75, 58.1% 3692, 20.1%
G H Where 4.667, 23.7% A = Number of sites with fixed gaps 4.000, 20.3% 0.00109, 20.3% 0.00127, 23.7% B = Total number of InDel sites C = Total number of InDel sites analysed 2.000, 10.2% 0.00055, 10.3% D = Total number of non-InDel sites analysed E = Total number of (InDel and non-InDel) sites analysed 3.000, 15.3% 0.00082, 15.3% F = Average InDel length G = InDel diversity, k(i) 6.000, 30.5% 0.00163, 30.4% H = InDel diversity per sites, π(i)
Figure 4-6: Frequency and percentage of InDel polymorphism of Ethiopian lowland bamboo ( O. abyssinica ).
4.2.6. Analysis of DNA Divergence
DNA divergence between populations was higher between populations of Metekel,
Oromia, Kemash and Assosa Zone Vs distant populations in chronological order (Figure
4-7). The k was higher between Metekel Zone Vs distant population (9.5), followed by
Oromia Vs distant population (8.667) and Kemash Zone Vs the distant population (8.467).
The least k was found between populations of Assosa Vs Kemash Zone and between
Assosa Zone Vs Oromia. The π(t) was higher between Metekel Zone Vs distant population
(0.00261), followed by Oromia Vs distant population (0.00238) and Kemash Zone Vs the
distant population (0.00234). The least π(t) was found between populations of Assosa Zone
Vs Kemash Zone and between Assosa Zone Vs Oromia.
55
The MP in P1, but monomorphic in P2 was higher between Metekel Zone Vs distant population (10), followed by Oromia Vs distant population (7) and Metekel Zone Vs
Oromia (5). The MP in P1, but monomorphic in P2 was found zero between populations
of Kemash Vs Metekel Zone and between Kemash Zone Vs Oromia. The MP in P2, but
monomorphic in P1 was higher between Assosa Zone Vs Metekel Zone (11) and between
Kemash Zone Vs Metekel Zone (11) followed by Kemash Zone Vs the distant population
(10). The least MP in P2, but monomorphic in P1 was found between populations of
Metekel Zone Vs Oromia followed by between Assosa Zone Vs Kemash Zone. The π between populations was higher between Kemash Zone (11.5), followed by Metekel Zone
(9.5) and Assosa Zone (9.333) Vs distant population. The least π between populations was
found between populations of Assosa Zone Vs Kemash Zone and between Assosa Zone
Vs Oromia.
56
Any population compared to the distant population found larger DNA divergence than others. This tells us DNA of the distant population is distinctly different from other populations. DNA divergence between Assosa Vs Kemash Zone, Assosa Vs Oromia, and Kemash Zone
Vs Oromia found to be smaller. Those three areas (Assosa Zone, Kemash Zone, and West Wellega and Buno Bedele Zones of Oromia
Region) are very close each other and there might be seed and/or seedling transfer between populations that make them close and related each other on their genetic makeup.
12 10 8 6 4 2 0 Assosa Assosa Assosa Assosa Kemash Kemash Kemash Metekel Metekel Oromia Zone vs Zone vs Zone vs Zone vs Zone vs Zone vs Zone vs Zone vs Zone vs vs Kemash Metekel Oromia Distant Metekel Oromia Distant Oromia Distant Distant Zone Zone Pop. Zone Pop. Pop. Pop. k 3 5.524 4.6 7.4 6.333 5.333 8.467 6.467 9.5 8.667 π(t) 0.00082 0.00153 0.00127 0.00202 0.00175 0.00146 0.00234 0.00179 0.00261 0.00238 MP in P1, but Monomorphic in P2 43340015107 MP in P2, but Monomorphic in P1 1 11 7 10 11 8 10 2 9 9 π between populations 3.5 5.75 5 9.333 6.75 6 11.5 6 9.5 8.5 Dx 0.00096 0.00159 0.00138 0.00255 0.00187 0.00165 0.00263 0.00166 0.00316 0.00233
Figure 4-7: DNA divergence between different Zones of Ethiopian lowland bamboo populations. Note: k denotes average number of nucleotide differences, π(t) - nucleotide diversity, MP - mutations polymorphic, P1 - population 1, P2 - population 2, π - average number of nucleotide differences, Dx - average number of nucleotide substitution per site between populations. 57
4.2.7. Gene Flow and Genetic Differentiation
Extremely higher frequency of genetic differentiation was found between Metekel Zone
Vs the distant population (51.63) and between Assosa Zone Vs Metekel Zone (51.50).
Least frequency was observed between Kemash Zone Vs Oromia (19.25) and between
Assosa Zone Vs Oromia (23.00). Higher frequency of gene flow was found between
Assosa Zone Vs Oromia (0.61) and between Kemash Zone Vs Oromia (0.50) and minimum frequency of gene flow was observed between Metekel Zone Vs the distant population
(0.02) and between Oromia Vs the distant populations (Table 4-6). This implicates that gene flow to Metekel Zone and the distant populations is rare and that makes diverse population as compared to others.
Table 4-6: Effects of gene flow and genetic differentiation on Ethiopian lowland bamboo. Genetic differentiation Gene flow Population comparison Ks Kxy Gamma St Fst Assosa Zone Vs Kemash Zone 16.60000 36.00000 0.56109 0.53241 Assosa Zone Vs Metekel Zone 36.52381 51.50000 0.32779 0.34142 Assosa Zone Vs Oromia 15.80000 23.00000 0.61075 0.60581 Assosa Zone Vs Distant Pop. 18.60000 40.16667 0.34696 0.15942 Kemash Zone Vs Metekel Zone 40.77778 40.50000 0.20076 0.13374 Kemash Zone Vs Oromia 17.00000 19.25000 0.60204 0.50318 Kemash Zone Vs Distant Pop. 20.50000 38.75000 0.58163 0.47097 Metekel Zone Vs Oromia 40.11111 34.87500 0.28104 0.27199 Metekel Zone Vs Distant Pop. 42.44444 51.62500 0.14885 0.02270 Oromia Vs Distant Pop. 19.50000 39.25000 0.38739 0.11688 Note: Ks denotes nucleotide sequence-based statistics, Kxy - average number of nucleotide differences between population 1 and population 2, GammaSt - genetic differences among population and Fst - average level of gene flow
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4.3. Discussion
Assessing the genetic diversity and population structure of any plant’s germplasm is a prerequisite for effective and successful improvement, conservation and management strategies of that plant (Sui et al., 2009). Furthermore, genetic diversity, population
structure, and gene flow analysis within different populations of a species are the main building blocks for understanding the evolutionary and speciation aspect of that species.
Oxytenanthera abyssinica is widely distributed in Ethiopia except for the eastern and southeastern parts of the country.
Genetic diversity is the basis for the ability of an organism to adapt to environmental changes and can be influenced by many factors (Amos and Harwood, 1998). Geographical factors (e.g. landscape, latitude, longitude, and altitude) and environmental factors (e.g. temperature and precipitation) influence the genetic diversity and population structure of a species and the individuals among populations (Wellenreuther et al., 2011; Pauls et al.,
2013). Biological factors such as mutation, genetic drift, mating system, pollination mode, gene flow, and selection also influence the diversity of plant species and population (Schaal et al., 1998).
Several studies applied on the genetic diversity of different bamboo species using phenotypic and different types molecular marker (GPWG, 2001; Nayak et al., 2003; Sun et al., 2006; Gami el al. , 2015). But studying the genetic diversity and population structure of O. abyssinica using either of phenotypic and molecular marker or both has not been done yet.
59
The k, π, and θw for the total sequence (coding + non-coding regions together) and coding and non-coding regions separately were used to calculate nucleotide diversity. The number of sites with fixed gaps, the total number of InDel and non-InDel sites, average InDel length, ki and π(i) were used to calculate InDel polymorphism. The k, π, and mutations polymorphic in population 1, but monomorphic in population 2 and vice-versa, the average number of nucleotide differences between populations, Dx for total sequence were used to calculate DNA divergence. Gamma St and Fs and Ks and Kxy were used to calculate gene flow and genetic differentiation.
The effectiveness of cpDNA regions for phylogenetics and genetic diversity studies are well approved and tested in many plants including prayer plant (Marantaceae) (Prince et al., 2006), palm (Chamaedoreeae) (Cuenca et al., 2008), 12 genera of angiosperms (Dong et al., 2012), paleotropical woody bamboos (Poaceae: Bambusoideae: Bambuseae)
(Chokthaweepanich, 2014), temperate woody bamboos (Attigala et al., 2015). As the
evolutionary rates of cpDNA are highly conserved with structural changes and nucleotides
substitution (Soltis et al., 2004), cpDNA regions that are coding ( matK and ndhF 3’ end) and non-coding ( rps16 ) genes were used to examine genetic diversities, population structure and gene flow analysis of O. abyssinica.
The NJ result retrieved three major clusters and three sub-clusters with five clades (Assosa
Zone, Kemash Zone, Metekel Zone, the distant population and the intermixed Oromia region samples) with their phylogeographic location. But MP result shows the mixing up
60 of some populations with others although major groups are almost similar to NJ. This approves that; phylogeography has a great impact on gene flow and genetic differentiation
(Avise, 2000). Generally, algorithms used to create phylogenetic trees with phylogenetic characteristics are more complex than methods based on distance (Scott & Gras, 2012). In this study, we found a mixing up of some populations with others in the MP method. But major groups are almost similar to NJ evolutionary tree construction method.
DnaSP can estimate multiple measurements of DNA sequence variations within and between populations in non-coding, synonymous or non-synonymous sites, or in different types of codon positions, as well as associating parameters of disequilibrium, recombination, gene flow and gene conversion (Rozas, Ferrer-Mata et al. 2017). Mainly mutations within the DNA are the source of variations. InDels are the main variation sources found within the genomes of various species of plants, including Arabidopsis (Hu
et al., 2011), rice (Lü et al., 2015), tomato (Yang et al., 2014) and chickpea (Das et al.,
2015). InDels usually occur by reason of certain cellular mechanisms, including
transposable elements movement, replication slippage and crossing-over imbalanced
within genomes (Moghaddam et al., 2014). InDels are essential phenomena that can have
a harmful or advantageous effect on specific genomes loci (Pearson et al., 2005; Garcia-
Diaz et al., 2006). Examination of DNA differences among closely related species or
among polymorphic DNA variations of a species will provide insight into mutations nature and evolution process (Britten et al., 2003). InDel analysis on O. abyssinica also shows
that; gene flow between distant populations found rare and genetic diferentioan becomes
higher.
61
Network analysis also shows that, haplotype 8 (Kurmuk sample of Assosa Zone) from gaps
or missing data considered and haplotype 2 (Bambasi sample of Assosa Zone) from gaps
or missing data not-considered has descendants around them, many of which differ from
them by nucleotide change (at sites shown by numbers), some are more distantly related.
Both the gaps and/or missing data considered and not-considered forms approve that,
Assosa Zone is the root of O. abyssinica and others diverge from this Zone. Amharic
Ambesa Chacka (meaning lion’s forest , because of high abundance of lions in the forest)
was one of sample collection site from Assosa Zone of Bambasi district. Years ago, the
area was known for its wide and dense lowland bamboo coverage. But now due to human’s
effect on the forest and/or deforestation, even small wild animals were out of our sight
during sample collection period for four days stay in a specified area.
Populations of O. abyssinica collected in Ethiopia showed clear diversity based on their geographic location. This might be due to the plant is indigenous to the country (Embaye,
2000) and largely abundant with broad geographical coverage for a long time, cross- pollination nature of the flower, and the distance between sample collections sites especially Zones was far and distant. Sample collection sites that have relatively closer distance like Assosa, Kemash, and Oromia, showed smaller nucleotide diversity (Table 4-
4), InDel (Table 4-5 and Figure 4-6), genetic differentiation (Table 4-6) and DNA divergence (Figure 4-7) but higher gene flow between populations (Table 4). These three sites are neighbor to each other. Assosa and Kemash Zones are under the administrative system of BGR and neighbor to each other with relative closer distance as compared to other sampling sites. Samples from Oromia are also neighbor to Kemash Zone. Thus, both
62 geographic range and distribution of populations influence patterns of genetic diversity, differentiation and gene flow of Ethiopian lowland bamboo (O. abyssinica ). Indeed, cross- pollination may have contributed to increasing the heterogeneity of bamboo seedlings
(John and Nadguada, 1999). This result is more in line with the study on African tropical
forest refugia using chloroplast and nuclear DNA phylogeography (Lowe et al., 2010),
classification of the Chloridoideae (Poaceae) based on multi-gene phylogenetic trees
(Peterson et al., 2010), Chinese Cherry revealed by chloroplast DNA trnQ-rps16 intergenic
spacer (Chen et al., 2013), natural populations of Oxalis laciniata from Patagonia
Argentina using ISSR and cpDNA based markers (López & Bonasora, 2017), wild soybean evaluated by chloroplast and nuclear gene sequences from 44 Chinese, four Japanese and five Korean populations (Wang et al., 2017) and endangered basal angiosperm Brasenia schreberi (Cabombaceae) in China using microsatellites (Li et al., 2018).
Based on the results retrieved, Metekel Zone showed the highest diversity among other populations and thus government sectors and other stakeholders are recommended to focus on conservation of lowland bamboo of Metekel Zone and carry out further study on O. abyssinica. The current study was performed only by few chloroplast coding and non- coding genes thus; additional coding, non-coding and spacer chloroplast and nuclear genes on Ethiopian lowland bamboo ( O. abyssinica ) might give additional information on the population genetic diversity, structure and gene flow.
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CHAPTER FIVE
5. Genetic Relationship among Indigenous and Introduced Bamboo Species and ISSR Markers Efficiency Analysis
5.1. Materials and Methods
5.1.1. Plant Material Collection and Sampling Strategy
The same plant materials (Table 3-2) used for the study of phylogenetic relationships among the indigenous and introduced bamboo species using cpDNA genes were also used here for phylogenetics study of introduced bamboo species over the indigenous Ethiopian bamboo species using ISSR markers. But leaf samples used for DNA extraction were silicagel dried. Five to seven young fresh leaves were stored in a zip lock plastic bag with appropriate silica gel. A single woody bamboo species was represented by three individuals for all the 31 species.
5.1.2. DNA Extraction and Primer Screening
Silicagel dried leaves were crashed by a mixer and miller (Retsch Mixer Mill MM 400).
Genomic DNA was isolated separately using a modified 2% CTAB DNA isolation method at Plant Molecular Biology Laboratory (PMBL) and Plant Genetics Research Laboratory
(PGRL) of AAU. Test gel electrophoresis in 1% agarose and nanodrop (Thermo
SCIENTIFIC NANODROP 2000 Spectrophotometer) of each sample was measured and those with high DNA quality used for PCR amplification after normalization of each sample to a concentration of 100ng. Gel documentation was taken by BIORAD Gel Doc TM
EZ System Imager.
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Fifteen ISSR primers were chosen out of 38 ISSR primers designed from University of
British Colombia (UBC) and previous work on the literature. Among fifteen primers, ten were di-nucleotide, one was tri-nucleotide, two were tetra-nucleotide, one was penta- nucleotide, and two were 5` anchored primers. Primers were further categorized into 3` anchored, 5` anchored, and un-anchored based on anchorage property (table 5-2).
Table 5-1: ISSR primers used for PCR amplification Primer Primers Nucleotide Repeat Anchorage Optimized No. name or selected Tm Sequence motifs property Ta Code for PCR
1 (AG) 8T UBC807 Dinucleotide 3’ -anchored
2 (AG) 8C UBC808 '' ''
3 (GA) 8T UBC810 '' '' √ 42
4 (GA) 8A UBC812 '' '' √ 42
5 (CT) 8T UBC813 '' ''
6 (CT) 8G UBC815 '' '' √ 42
7 (TC) 8C UBC823 '' ''
8 (TC) 8G UBC824 '' '' √ 43
9 (AC) 8T UBC825 '' ''
10 (AG) 8YT UBC834 '' '' √ 43
11 (AG) 8YC UBC835 '' '' √ 45
12 (GA) 8YT UBC840 '' '' √ 42
13 (GA) 8YC UBC841 '' '' √ 43
14 (GA) 8YG UBC842 '' ''
15 (CT) 8RC UBC844 '' '' √ 43
16 (CT) 8RG UBC845 '' ''
17 (CA) 8RG UBC848 '' ''
18 (GT) 8YG UBC851 '' ''
19 (TC) 8RT UBC853 '' ''
20 (TC) 8RG UBC854 '' ''
21 (AC) 8YG UBC857 '' ''
22 (ACC) 6 UBC861 Tri Unanchored
23 (AGC) 6 UBC862 '' ''
24 (AGT) 6 UBC863 '' ''
25 (ATG) 6 UBC864 '' '' √ 39
26 (GATA) 4 UBC872 Tetra “
27 (GACA) 4 UBC873 '' '' √ 42
28 (CCCT) 4 UBC874 '' ''
29 (CTAG) 4 UBC875 '' ''
30 (GATA)2(GACA) 2 UBC876 '' '' √ 39 65
31 (CTTCA) 3 UBC879 Penta ''
32 (GGAGA) 3 UBC880 '' '' √ 45
33 (GGGTG) 3 UBC881 '' ''
34 BDB(CA) 7 UBC888 5’-anchored 5’-anchored √ 47
35 DBD(AC) 7 UBC889 '' '' √ 45
36 (AGG) 6 ISSR_1 Tri Unanchored
37 (GACAC) 4 ISS R_2 Penta ''
38 (ACTG) 4 ISSR_3 Tetra '' Y = C or T ‰ (PYramidine), R = A or G ‰ (PuRine), B = C, G, or T ‰ (not A), D = A, G, or T ‰ (not C)
5.1.3. ISSR-PCR Amplification and Gel Electrophoresis
Each DNA amplification reaction was performed in a final volume of 10µl containing 5.5
µl 2x Taq plus Master Mix (containing Taq DNA polymerase, dNTPs, MgCl 2, PCR buffer,
PCR reaction enhancer, stabilizer and a blue tracer dye), 3.5 µl ddH 2O, 0.5 µl ISSR primer and 0.5 µl normalized genomic DNA. The blue dye and a stabilizer of 2x Taq plus Master
Mix help to directly load the final products onto a gel for analysis. The thermal profile included pre-PCR denaturation at 94 °C for 4 minutes followed by 35 cycles of denaturing at 94 °C for 30 seconds, annealing (39 - 47 °C) for 30 seconds (Table 5-1), extension at
72°C for 1 minute and a final extension at 72 °C for 10 minutes. The PCR products were stored at 4 °C until loading on gel electrophoresis. About 5 µl of ISSR-amplification product of each sample DNA was loaded on and were resolved in 1.67% agarose gels in
0.5x TBE buffer at 100 V constant for 1:30 - 2h. The agarose solution was stained with 3.0
µl Ethidium Bromide (EtBr) after the boiling of the powder and 0.5% TBE buffer. The
ISSR profiles were visualized and photographed under BIORAD Gel Doc TM EZ System
Imager that connected to PC with Image Lab software, and stored for later data scoring. To
estimate the molecular sizes of the resolved fragment, 100 bp DNA markers were used.
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5.1.4. Scoring and Data Analysis
Bands were scored manually. According to the weight of the DNA ladder (100 bp), the same weight bands were marked as a line. The bands that were clearly visible and repeatable on the electrophoresis map were marked as “1”, the absence of a band at the same site was marked as “0” and “?” for the ambiguous bands that were not clearly shown were scored as a missing data. Intensity variations among fragments having approximately the same molecular size were not considered although in some cases intensity differences of the bands were observed. A binary data matrix was compiled with individuals in the column and the ISSR markers in the row for each primer set and vise-versa according to the requirements of the software’s. Each amplified fragment was named by the code of the primers across the row and/or column followed by the Arabic numbers starting from the fragment having high molecular weight to the fragments with low molecular weight. Both the total number of bands amplified by each primer and the number of polymorphic bands were calculated. On the basis of the recorded band profiles, different software was employed for the analysis of the data.
POPGENE version1.32 (Yeh et al., 1999) and GenAlEx version 6.5 (Peakall and Smouse,
2012) were used to calculate number of polymorphic loci, percent polymorphism, gene diversity and Shannon diversity index. Shannon diversity index (H) was calculated asH = -
n ∑i=1 Pi ln 2 Pi where pi is the frequency of a given band for each population (Lewontin,
1972). Shannon’s index of diversity was used to measure the total diversity (Hsp) for the species as well as the mean diversity per population (Hpop). The proportion of diversity