Mutational effects of carbon ions near the range end in Arabidopsis

Hase, Yoshihiro; Nozawa, Shigeki; Narumi, Issey*

Little is known about the mutational effects of ion beams near the range end, especially in plants. We analyzed the mutations occurred in the Arabidopsis gene with the emphasis on large deletions. The frequency of glabrous mutant sectors, which is caused by inactivation of gene, was not significantly different between the carbon ions near the range end (mean LET: 425 keV/m, C (425)) and 208 MeV Carbon ions (113 keV/m, C (113)), while the C (425) induced large deletions ( 5 kb) more frequently by 6 times than C (113). These results suggested that the frequency of large deletions is affected by LET. Mutations that have deletion in either one or both of the nearest DNA markers (3.9 kb upstream and 2.8 kb downstream of gene) were further examined to evaluate the total size of deletions. The most of the deletions were larger than 200 kb and the largest deletion was estimated to be more than several Mb. Similar results were obtained in the case of neon ions with a mean LET of 352 keV/m. These results suggest that deletions larger than 200 kb are often induced by the ion beams with a LET higher than 100 keV/m.