Structural and Regulatory Genes Controlling the Biosynthesis of Essential Oil Constituents in Lavender
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STRUCTURAL AND REGULATORY GENES CONTROLLING THE BIOSYNTHESIS OF ESSENTIAL OIL CONSTITUENTS IN LAVENDER By Lukman Syed Sarker M.Sc., University of British Columbia, 2013 M.Sc., University of Dhaka, 2009 B.Sc., University of Dhaka, 2007 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OFTHE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE COLLEGE OF GRADUATE STUDIES (Biology) THE UNIVERSITY OF BRITISH COLUMBIA April 2020 © Lukman Sarker, 2020 i The following individuals certify that they have read, and recommend to the College of Graduate Studies for acceptance, a thesis/dissertation entitled: Structural and regulatory genes controlling the biosynthesis of essential oil constituents in lavender Submitted by Lukman Sarker in partial fulfillment of the requirements of the degree of Doctor of Philosophy Dr. Soheil S. Mahmoud, Biology, Irving K. Barber School of Arts and Sciences, UBC Supervisor Dr. Michael Deyholos, Biology, Irving K. Barber School of Arts and Sciences, UBC Supervisory Committee Member Dr. Mark Rheault, Biology, Irving K. Barber School of Arts and Sciences, UBC Supervisory Committee Member Dr. Frederic Menard, Chemistry, Irving K. Barber School of Arts and Sciences, UBC University Examiner Dr. Philipp Zerbe, Department of Plant Biology, University of California External Examiner Additional Committee Members include: Dr. Thu-Thuy Dang, Chemistry, Irving K. Barber School of Arts and Sciences, UBC Supervisory Committee Member ii Abstract This thesis describes research conducted to enhance our understanding of essential oil (EO) metabolism in lavender (Lavandula). Specific experiments were carried out in three areas. First, we developed a comprehensive transcriptomic database to facilitate the discovery of novel structural and regulatory essential oil biosynthetic genes in lavender. The database includes 101,618 contigs (N50 = 831 bp), over 75% of which were successfully annotated. Annotated sequences include full length transcripts for all previously reported genes involved in the MVA and MEP pathways of isoprenoid metabolism, all prenyltransferases involved in the isoprenoid biosynthesis, and all terpene synthase genes cloned from various lavender species. They also contain novel EO-related genes, as exemplified by the S-linalool synthase (Li(S)-LINS) gene we cloned using this database. Further, the database contains 1633 TFs, representing 2.1% of the lavenders' transcriptome, some of which have been shown to regulate secondary metabolism in plants. The most abundant TF families were bHLH (209), WRKY (190), and MYB (189) followed by AP2 (79), bZIP (77), and zinc finger (19), NAC (13), and MYC (9). Second, we isolated the 5' upstream genomic DNA (promoter) sequences for linalool synthase (LiLINS) and 1,8-cineole synthase (LiCINS) genes from L. x intermedia and used them to conduct a Yeast One-Hybrid Assay in order to identify TFs that regulate the expression of LiLINS and LiCINS genes in this plant. The assay identified 96 proteins that interacted with one or both promoters. To elucidate the nature of this interaction further, the LiLINS and LiCINS promoter fragments were each fused to the E. coli gusA (GUS) reporter gene. The constructs were separately transformed into tobacco (Nicotiana benthamiana) leaves, co-expressing individually a subset of ten representative transcription factors. Six TFs iii induced expression from both promoters, two activated LiCINS promoter alone, and two did not induce expression from either promoter. Finally, we isolated and functionally characterized genes for two acetyltransferases, LiLAT-3 & LiLAT-4, which convert some of the monoterpene EO constituents into their respective esters in lavender. Our results, which have enhanced our understanding of EO biosynthesis in plants, will help improve EO yield and composition in lavender and other plants through plant breeding and biotechnology. iv Lay Summary Lavender is an economically important plant known for its essential oils (EO), which is dominated by a group of small, volatile biochemical compounds known as monoterpenoids. To understand the genetic basis of lavender EO constituent production, we developed a comprehensive transcriptome database, which facilitates the discovery of structural and regulatory genes involved in terpenoids biosynthesis, as well as other important processes such as defense against pest and herbivores. Further, we employed a Yeast One-Hybrid Assay to identify transcription factors that control the expression of two important genes responsible for the production of linalool and cineole in lavenders. Finally, we cloned genes for two acetyltransferase enzymes involved in the conversion of monoterpenes to their corresponding esters in lavender plants. v Preface Chapter 2 has been published in a journal Planta and the contents were reprinted/ adapted by permission from Springer Nature: Planta, 249(1):271–290, RNA-Seq in the discovery of a sparsely expressed scent-determining monoterpene synthase in lavender (Lavandula), Ayelign M. Adal, Lukman S. Sarker, Radesh PN Malli, Ping Liang and Soheil S. Mahmoud, © 2018, License # 4718011260334. I designed the experiment to develop the lavender transcriptomic database. I also helped Ayelign Adal to clone the S-linalool synthase. I helped in the writing procedure; however, Ayelign Adal led the manuscript preparation with the guidance of Dr. Soheil Mahmoud. Both Lukman Sarker and Ayelign Adal share an equal contribution in publishing this manuscript. Mr. Radesh PN Malli and Dr. Ping Liang analyzed genomic seq and copy numbers of S-linalool synthase in the genome. Chapter 3 has been published in Planta, and the contents were reprinted/ adapted by permission from Springer Nature: Planta, (2020) 251: 5 (online version), Diverse transcription factors control monoterpene synthase expression in lavender (Lavandula). Lukman S. Sarker, Ayelign M. Adal, and Soheil S. Mahmoud, © 2019, License # 4718020130702. I have designed and conducted the experiment. Ayelign Adal took the lead to write the manuscript with the help of myself and Dr. Soheil Mahmoud. Chapter 4 has been published in Planta, and the contents were reprinted/ adapted by permission from Springer Nature: Planta, 242 (3): 709-19. Cloning and functional characterization of two monoterpene acetyltransferases from glandular trichomes of L. x intermedia. Lukman S. Sarker and Soheil S. Mahmoud, © 2015, License vi #4718020297429. I have designed and conducted the experiments and wrote the manuscript with the guidance of Dr. Soheil Mahmoud. During my Ph.D. thesis work, I also co-authored the following manuscripts: a) Malli RPN, Adal AM, Sarker LS, Liang P, and Mahmoud SS (2019) De novo sequencing of the Lavandula angustifolia genome reveals highly duplicated and optimized features for essential oil production, Planta, 249(1):251–256. (I collected leaf tissues, prepared genomic DNA for sequencing and provided ESTs and transcriptomes for annotation). b) Wells R, Truong F, Adal AM, Sarker LS, and Mahmoud SS (2018) Lavandula essential oils: a current review of applications in medicinal, food, and cosmetic industries of lavender. Natural Product Communications, 13(10): 1403-1417. (I wrote a section of the review and helped with reference management and manuscript preparation). c) Adal AM, Sarker LS, Lemke A, Mahmoud SS (2017) Isolation and functional characterization of a methyl jasmonate-responsive 3-carene synthase from Lavandula x intermedia. Plant Molecular Biology, 93: 641-657. I helped Ayelign Adal with qPCR experimentation and writing the manuscript. vii Table of Contents Abstract ................................................................................................................................... iii Lay Summary .......................................................................................................................... v List of Tables .......................................................................................................................... xi Table of Figures..................................................................................................................... xii List of Symbols ..................................................................................................................... xiv Acknowledgments ................................................................................................................ xvi Dedication............................................................................................................................ xviii 1 Chapter: Introduction ...................................................................................................... 1 1.1 Biosynthesis of lavender terpenoids .......................................................................................... 3 1.1.1 Isoprene biosynthesis ...................................................................................................... 4 1.1.2 Mono- and sesquiterpene synthesis ................................................................................. 7 1.1.2.1 Mono and sesquiterpene synthases .......................................................................... 8 1.1.2.2 EO Esters and ketones in lavender ......................................................................... 10 1.2 Storage and secretion of volatile terpenoids ............................................................................ 11 1.3 Regulation of terpenoid synthesis ...........................................................................................