Host: The Japan Radiation Research Society, Chairman of the 52nd Annual Meeting, Toshiteru Okubo (Radiation Effects Research Foundation)
Although radiation has been used as the mutagen in mutation breeding, little is known about which types of mutation are induced in plant DNA. In this study, we irradiated carbon ion-beams (220-MeV C : LET=112 keV/μm) and γ-rays to Arabidopsis carrying rpsL gene to analyze mutational effects of these radiations. G:C to A:T transition and > 2 bp deletions/insertions were the major type of mutation by the irradiation of 220-MeV C and γ-rays to Arabidopsis dry seeds. The incidence of −1 and −2 frameshift mutations was also higher in γ-ray-irradiation group, suggesting that γ-rays might induce smaller size of deletion mutation compared to 220-MeV C. Our observation also suggested that induction of oxidized guanine by 220-MeV C and γ-rays was low in dry seeds because of low incidence of G:C to T:A and A:T to C:G transversion in irradiated group. We irradiated γ-rays to Arabidopsis seedling to assess the mutational effect of oxidative DNA damage in plant. Water contents and cell proliferating activity of Arabidopsis seedling are higher than dry seed. Therefore we thought the effect of water radiolysis and misincorporation of oxidized dNTPs during replication could have been investigated. Our result of γ-ray-induced mutation analysis in Arabidopsis seedling was similar to that in dry seed. G:C to T:A and A:T to C:G transversion were not increased, suggesting the mutational effect of radiation used here in higher plant might be different from that in other organisms.
