Mutational effects of UV and ionizing radiations in higher plants; Mutation spectrum analysis using

Yoshihara, Ryohei; Takimoto, Koichi*; Hase, Yoshihiro; Nozawa, Shigeki; Sakamoto, Ayako; Narumi, Issei

We constructed a mutation detection system by integrating a linearized plasmid DNA that has gene into the chromosomal DNA of . We first analyzed the UV-induced mutation spectrum. The frequency of G to A transitions was increased after the exposure to UV light. To evaluate the effects of photorepair activity for CPDs in maintaining genomic integrity, we constructed RNAi plants in which the expression of CPD photolyase was suppressed. The mutation spectrum analysis in the RNAi plants showed that the frequency of frameshift mutations was increased together with that of G to A transitions. This suggests that the suppression of CPD photorepair not only increase the typical base substitutions but also other kinds of mutations. We next analyzed the mutation spectrum induced by rays and carbon-ion beams (LET 121.5 keV/m). The results showed that rays tended to induce shorter size of deletions than the carbon ions.