Epigenetic changes and transposon reactivation in Thai rice hybrids |
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Authors: | Laksana Kantama Supaporn Junbuathong Janejira Sakulkoo Hans de Jong Somsak Apisitwanich |
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Affiliation: | 1. Faculty of Liberal Arts and Science, Kasetsart University, Kamphaengsaen Campus, Nakorn Pathom, 73140, Thailand 2. Pathumthani Rice Research Centre, Bureau of the Research and Development, Rice Department, Minister of Agriculture and Cooperation, Pathum Thani, Thailand 3. Department of Genetics, Faculty of Science, Kasetsart University, Bangkhen Campus, Bangkok, 10900, Thailand 5. Laboratory of Genetics, Wageningen University, P.O. Box 309, 6700 AH, Wageningen, The Netherlands 4. Center of Advanced studies for Tropical Natural Resources, Kasetsart University, Bangkok, 10900, Thailand
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Abstract: | Inter- or intraspecific hybridization is the first step in transferring exogenous traits to the germplasm of a recipient crop. One of the complicating factors is the occurrence of epigenetic modifications of the hybrids, which in turn can change their gene expression and phenotype. In this study we present an analysis of epigenome changes in rice hybrids that were obtained by crossing rice cultivars, most of them of indica type and Thai origin. Comparing amplified fragment length polymorphism (AFLP) fingerprints of twenty-four cultivars, we calculated Nei’s indexes for measuring genetic relationships. Epigenetic changes in their hybrids were established using methylation-sensitive AFLP fingerprinting and transposon display of the rice transposable elements (TEs) Stowaway Os-1 and Mashu, leading to the question whether the relationship between parental genomes is a predictor of epigenome changes, TE reactivation and changes in TE methylation. Our study now reveals that the genetic relationship between the parents and DNA methylation changes in their hybrids is not significantly correlated. Moreover, genetic distance correlates only weakly with Mashu reactivation, whereas it does not correlate with Stowaway Os-1 reactivation. Our observations also suggest that epigenome changes in the hybrids are localized events affecting specific chromosomal regions and transposons rather than affecting the genomic methylation landscape as a whole. The weak correlation between genetic distance and Mashu methylation and reactivation points at only limited influence of genetic background on the epigenetic status of the transposon. Our study further demonstrates that hybridizations between and among specific japonica and indica cultivars induce both genomic DNA methylation and reactivation/methylation change in the Stowaway Os-1 and Mashu transposons. The observed epigenetic changes seem to affect the transposons in a clear manner, partly driven by stochastic processes, which may account for a broader phenotypic plasticity of the hybrids. A better understanding of the epigenome changes leading to such transposon activation can lead to the development of novel tools for more variability in future rice breeding. |
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