Transpositional Activation Of Two Endogeneous Mobile Elements Inducing By The Tissue Culture In Rice (Oryza Sativa L.) Genome

In this thesis, regenerated plants were obtained from embryonic calli induced from eachof several rice–Zizania introgression lines, their rice parental line (Matsumae) as well as F1hybrids between introgression lines and the parental line, by using mature seeds as explants.Transpositional activity of two typical transposable elements, a MITE transposon mPing and aLTR-type retrotransposon Tos17 were analyzed in the regenerated rice plants of various lines.Results showed that compared to uncultured seed-plants, mPing was active in regeneratedplants of some of the lines whereas Tos17 was active in all lines. Of particular interest are thefindings that the transpositional frequencies of the two mobile elements appeared to be verydifferent both between the introgression lines and their rice parent, and between F1 hybridsand their parental lines. This suggests importance of genotype in controlling activity ofmobile elements under tissue culture conditions. Possible causes of these phenomena arediscussed.