Kantama L.,Kasetsart University |
Junbuathong S.,Pathumthani Rice Research Center |
Sakulkoo J.,Kasetsart University |
de Jong H.,Wageningen University |
Apisitwanich S.,Kasetsart University
Molecular Breeding | Year: 2013
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. © 2013 Springer Science+Business Media Dordrecht.
Calingacion M.,International Rice Research Institute |
Calingacion M.,Wageningen University |
Laborte A.,International Rice Research Institute |
Nelson A.,International Rice Research Institute |
And 48 more authors.
PLoS ONE | Year: 2014
With the ever-increasing global demand for high quality rice in both local production regions and with Western consumers, we have a strong desire to understand better the importance of the different traits that make up the quality of the rice grain and obtain a full picture of rice quality demographics. Rice is by no means a 'one size fits all' crop. Regional preferences are not only striking, they drive the market and hence are of major economic importance in any rice breeding / improvement strategy. In this analysis, we have engaged local experts across the world to perform a full assessment of all the major rice quality trait characteristics and importantly, to determine how these are combined in the most preferred varieties for each of their regions. Physical as well as biochemical characteristics have been monitored and this has resulted in the identification of no less than 18 quality trait combinations. This complexity immediately reveals the extent of the specificity of consumer preference. Nevertheless, further assessment of these combinations at the variety level reveals that several groups still comprise varieties which consumers can readily identify as being different. This emphasises the shortcomings in the current tools we have available to assess rice quality and raises the issue of how we might correct for this in the future. Only with additional tools and research will we be able to define directed strategies for rice breeding which are able to combine important agronomic features with the demands of local consumers for specific quality attributes and hence, design new, improved crop varieties which will be awarded success in the global market.