@misc{oai:repo.qst.go.jp:00066886,
 author = {長谷, 純宏 and 長谷 純宏},
 month = {Aug},
 note = {The major goal of our research is to elucidate the mutagenic effects of ion beams and the development of efficient mutagenic techniques. The molecular nature of mutations induced by ion beams is being discovered since the 2000s. It is the current understanding that ion beams tend to induce deletions and structural alterations of chromosomes more frequently than gamma-rays or X-rays, and this tendency is more evident as the LET value of ion beams increases. Generally, mutation breeding is perceived as a random process and no effective methods have been established to control the direction of mutations in practical mutation breeding. We investigated the mutation frequency using 7,258 chrysanthemum plants regenerated from petal and leaf tissues irradiated with 1 - 5 Gy of argon ions. We demonstrated that more flower colour mutants were obtained from cultured petals than from leaves irradiated by ion beams, whereas the regeneration frequency and the stem length of the regenerated plants did not differ between these two tissues. Similarly, in petunia seedlings, sucrose treatment to stimulate pigment biosynthesis resulted in a higher frequency of flower colour mutants after 8 Gy of carbon-ion irradiation compared to mock treated controls, although the frequency of chlorophyll mutants was unaffected. Most recently, we compared the characteristics of mutations in Arabidopsis derived from dry seeds and seedlings, both irradiated with carbon ions. Dry seeds and 7-day-old seedlings were irradiated with doses corresponding to 50% and 75% of the shoulder dose of survival curve for each material (125 and 175 Gy for dry seeds, and 20 and 30 Gy for seedlings). Whole-genome re-sequencing of randomly chosen M2 plants (six independent plants for each dose) revealed that the frequency of Indels was about three times higher in dry-seed irradiation than in seedling irradiation, while the frequency of single base substitution was not significantly different. These results suggested that the physiological status of plant tissue greatly affects the frequency and type of mutations. These findings are highly relevant for developing more efficient mutagenesis techniques and also for understanding the molecular mechanism of mutagenesis by ionizing radiation., FAO/IAEA International Sympodium on Plant Mutation Breeding and Biotechnology},
 title = {Mutagenic effects of ion beams and development of efficient mutagenesis techniques},
 year = {2018}
}