Mutational effects of -rays and carbon ion beams in seedlings

Yoshihara, Ryohei*; Nozawa, Shigeki; Hase, Yoshihiro; Narumi, Issei; Hidema, Jun*; Sakamoto, Ayako

To assess the mutational effects of radiations in vigorously proliferating plant tissue, mutation spectrum was analyzed with seedlings via plasmid rescue method. Transgenic plants containing gene were irradiated with -rays and carbon ion beams (320 MeV C), and mutations in the gene were analyzed. Mutant frequency was significantly increased by -rays, but not by 320 MeV C. Mutation spectrum showed that both radiations increased the frequency of frameshifts and other mutations including deletion/insertion but that only -rays increased the frequency of total base substitutions. These results suggest that the type of DNA lesions which cause base substitutions were less induced by 320 MeV C than by -rays in seedlings. -rays never increased the frequencies of G:C to T:A and A:T to C:G transversions, which are caused by oxidized guanine, though 320 MeV C slightly increase the both transversions. Instead, -rays significantly increased the frequency of G:C to A:T transition. These results suggest that 8-oxoguanine has little effect on mutagenesis in cells.