P Chromosomes Involved in Intergenomic Rearrangements of Kengyilia Thoroldiana Affected by the Environment

c Indian Academy of Sciences

RESEARCH NOTE

P chromosomes involved in intergenomic rearrangements of Kengyilia thoroldiana affected by the environment

QIUXIA WANG1,2, HAIMING HAN1, AINONG GAO1, XINMING YANG1 and LIHUI LI1∗

1The National Key Facilities for Crop Gene Resources and Genetic Improvement, The National Key Facilities for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, People’s Republic of China 2Institute of Special Wild Economic Animals and Plants, Chinese Academy of Agricultural Sciences, Changchun, Jilin, People’s Republic of China

[Wang Q., Han H., Gao A., Yang X. and Li L. 2014 P chromosomes involved in intergenomic rearrangements of Kengyilia thoroldiana affected by the environment. J. Genet. 93, 199–202]

Introduction and Z2633 from 4710 m, were selected from the nine populations (Wang et al. 2012) in the present study. Chromosome rearrangement plays an important role in plant evolution, being ubiquitous after polyploidization. Genomic changes in resynthesized and natural polyploids are com- Materials and methods mon consequences of polyploidization across a wide range of species (Wendel 2000;Chen2007; Hegarty and Hiscock Materials 2005; Leitch and Leitch 2008; Soltis and Soltis 2009; Gaeta Two populations, Z2538 from 4015 m and Z2633 from and Pires 2010;Wanget al. 2012; Lavania et al. 2012). 4710 m, were selected from the nine populations of Newly formed polyploid hybrids are not true species unless K. thoroldiana, and three to five individuals including they are genetically, ecologically or reproductively isolated chromosome translocations that we had detected in the from their parental taxa (Ungerer et al. 1998). It is assumed two populations were randomly selected for two-colour that chromosome rearrangements facilitate the establishment genomic in situ hybridization (GISH) and fluorescence in situ of newly formed polyploid as successful species (Wendel hybridization (FISH) analyses separately (Wang et al. 2012). et al. 1995; Feldman et al. 1997; Hegarty and Hiscock 2008). Chromosomes were prepared as described by Wu et al. The P genome is important in Triticeae and is found (2006). in the genera Agropyron, Kengyilia and Douglasdeweya.It has always been considered independently inherited, and no genes were transferred from the P genome to others with- Labelling of probes out biotechnology (Dewey 1984; Jensen and Griffin 1994). However, we found that the P genome did not behave inde- Total genomic DNA were extracted from young leaves of = = pendently, but was very active and subject to natural rear- Pseudoroegneria spicata (2n 2x 14, StSt), Agropyron = = rangements with other genomes after polyploidization, and cristatum (2n 4x 28, PPPP), Triticum aestivum L. cv. = = frequency and type of intergenomic rearrangements between Chinese Spring (2n 6x 42, AABBDD) and Brachy- the relatively large P genome and the small genomes, St and podium sylvaticum (L.) Beauv., using phenol–chloroform Y, were affected predominantly by ecological factors and extraction (Sharp et al. 1988) as modified by Devos et al. altitude in nine populations of Kengyilia thoroldiana (Wang (1993). Total genomic DNA of Pd. spicata and A. cristatum et al. 2012). To investigate the effects of different altitudes on were labelled separately with Biotin-Nick-Translation Mix different P chromosomes involved in intergenomic transloca- (Roche, Mannheim, Germany) and Dig-Nick-Translation tions in K. thoroldiana, two populations, Z2538 from 4015 m Mix (Roche) for two-colour GISH. FISH was carried out using the followings as probes: a subfamily clone of the pAs1 repetitive sequence originally cloned by Rayburn and Gill (1986) from Aegilops squar- ∗ For correspondence. E-mail: [email protected]. rosa, and the pHvG39 sequence containing GAA satellite Keywords. Triticeae; P chromosomes; intergenomic rearrangements; environment.

Journal of Genetics, Vol. 93, No. 1, April 2014 199 Qiuxia Wang et al.

Figure 1. Identification of rearrangements among St, P, and Y genomes in population Z2538. Red colour indicates fragments of P chromosomes, blue colour indicates fragments of Y chromosomes for GISH (a); pAs1 repetitive DNA probe signal is green, pHvG39 repetitive DNA probe signal is red for FISH (b). sequences amplified from the genomic DNA of Hordeum Results vulgare (Pedersen and Langridge 1997).ThepAs1and pHvG39 sequences were labelled separately by Biotin-Nick Identification of rearrangements among St, P and Y genomes Translation Mix (Roche) and Dig-Nick-Translation Mix in K. thoroldiana (Roche). St, P and Y chromosome translocations were identified using GISH and FISH in both populations (figure 1).

GISH and FISH analyses The two-colour GISH and FISH methods were adopted from Wang et al. (2010). The chromosomes of 5–10 cells for each individual were used to identify genotype after GISH and FISH, and P chromosomes were named and arranged according to Wang et al. (2010).

Figure 2. Idiogram of the P chromosomes in one individual Figure 3. Idiogram of the P chromosomes in two individuals including translocation chromosomes from population Z2538. Red including translocation chromosomes from population Z2633. Red colour indicates fragments of P chromosomes, blue colour indi- colour indicates fragments of P chromosomes, blue colour indicates fragments of Y chromosomes for GISH; pAs1 repetitive DNA cates fragments of Y chromosomes for GISH; pAs1 repetitive DNA probe signal is green, pHvG39 repetitive DNA probe signal is red probe signal is green, pHvG39 repetitive DNA probe signal is red for FISH. for FISH.

200 Journal of Genetics, Vol. 93, No. 1, April 2014 P chromosomes involved in intergenomic rearrangements

P chromosomes involved in intergenomic rearrangements extremely variable and harsh according to Piao et al. (2006). in population Z2538 The complex and changeable environment of the Tibetan Five individuals including chromosome translocations were Plateau region may disturb normal chromosome pairing in used for GISH and FISH analyses in population, Z2538. The meiosis in K. thoroldiana, consequently leading to genome P chromosomes involved in translocations in the five indi- rearrangements (Wang et al. 2012), thus it could influence viduals were all 1P and 7P, and the breakpoints of 1P and 7P the P chromosomes involved in translocations so much, and were all near centromere on the long arm (figure 2). even the P chromosomes of very low polymorphisms were involved in translocation. The effects of the environment on different chromosomes evolution of the same genome are different. P chromosomes involved in intergenomic rearrangements in population Z2633 Three individuals including chromosome translocations were Acknowledgements used for GISH and FISH analyses in population, Z2633. The Financial support provided by the National Key Technology R & D P chromosome involved in translocations in one individual Programme (project no. 2013BAD01B02) is gratefully appreciated. was 5P with the breakpoint at the terminal region on the long We are very grateful to BioMedES Ltd (Inverurie, Aberdeenshire, arm (figure 3a). The P chromosomes involved in transloca- AB51 0LX, UK) for improving the article linguistically. tions in another two individuals were all 2P chromosomes and the breakpoints of 2P were all near centromere on the short arm (figure 3b). References

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Received 12 August 2013, in revised form 9 October 2013; accepted 17 October 2013 Published on the Web: 8 April 2014

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