Mobilization Of Transposons MPing And Pong And Alterations In DNA Methylation Induced By γ Irradiation In Rice

γirradiation is a traditional method for crop improvement. Here, we used molecular technology to study the possible epigenetic alterations induced by the irrradiation.Transposons are genetic elements that can move or sometimes spread within their host genomes. Activatin of mobile elements induced by specific inducible conditions is important to further understand the biological roles of this epigenetic modification. We found in this study that 60Coγirradiated rice seeds produced plants with much lower rate of germination, and several apparent phenotypic mutate traits including later-riping and albino . Transposon display (TD) analysis on randomly selected mutant individuals indicated that mPing, a recently discovered endogenous MITE (miniature inverted repeat transposable element) in rice, together with its putative transposase-encoding partners Pong, was mobilized in somatic cells of these rice plants. And mutated individuals tended to have many mPing and Pong insersion events, base on mPing-horboring locus-specific PCR assays.Intrinsic DNA methylation pattern is an integral component of the epigenetic network in many eukaryotes. We analysed three hyper-methylated mobile elements by the McrBC digestion, and found that they appeared obviously hypo-methylation alteration. In contrast, the methylation sensitive amplified polymer-phism (MSAP) assays indicated that M0 individuals appeared hyper-methylation.Based on the above observations, we conclude that 60Coγirradiation represents a effective mutagen for rice, by not only inducing classical sequences alterations, but also the epigenetic changes including activation of mobile elements and alterations in DNA methylation patterns. So the study may provide some reference information for designging irradiation-based crop muational breeding.