Abstract
We have developed fifty thousands insertion lines using the endogenous retrotransposon Tos17. Large scale phenotyping for mutant lines shows that half of mutant lines have at least one phenotypic change. However, co-segregation analysis between genotype of Tos17 and phenotype indicates relatively low efficient for tagging by Tos17. We have been analyzing the whole genome sequence of regenerated rice plants to detect cause of the somaclonal variation. We sequenced two lines of regenerated rice at M4 stage using a next-generation sequencer (Solexa). At least, 1 mutation / Mb in the regenerated plant at M1 stage is estimated. Estimated mutations were validated by Dyedeoxy terminator method. The mutation spectrum of somaclonal variation is analogous to the spectrum of spontaneous mutation of Arabidopsis except the relatively low level of transition from C to T. The C to T transition is caused by deamination of methyl-cytosine. Because no enzymatic repairing process in the deamination of methyl-cytosine, it is suggested that the high frequency of mutations in somatic cells is caused by suppression of mutation repairs.
