title: Molecular nature of mutations induced by high-LET irradiation with argon and carbon ions in Arabidopsis thaliana.
abstract: Linear energy transfer (LET) is an important parameter to be considered in heavy-ion mutagenesis. However, in plants, no quantitative data are available on the molecular nature of the mutations induced with high-LET radiation above 101-124keVμm(-1). In this study, we irradiated dry seeds of Arabidopsis thaliana with Ar and C ions with an LET of 290keVμm(-1). We analyzed the DNA alterations caused by the higher-LET radiation. Mutants were identified from the M(2) pools. In total, 14 and 13 mutated genes, including bin2, egy1, gl1, gl2, hy1, hy3-5, ttg1, and var2, were identified in the plants derived from Ar- and C-ions irradiation, respectively. In the mutants from both irradiations, deletion was the most frequent type of mutation; 13 of the 14 mutated genes from the Ar ion-irradiated plants and 11 of the 13 mutated genes from the C ion-irradiated plants harbored deletions. Analysis of junction regions generated by the 2 types of irradiation suggested that alternative non-homologous end-joining was the predominant pathway of repair of break points. Among the deletions, the proportion of large deletions (>100bp) was about 54% for Ar-ion irradiation and about 64% for C-ion irradiation. Both current results and previously reported data revealed that the proportions of the large deletions induced by 290-keVμm(-1) radiations were higher than those of the large deletions induced by lower-LET radiations (6% for 22.5-30.0keVμm(-1) and 27% for 101-124keVμm(-1)). Therefore, the 290keVμm(-1) heavy-ion beams can effectively induce large deletions and will prove useful as novel mutagens for plant breeding and analysis of gene functions, particularly tandemly arrayed genes.
authors.affiliation: Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Tomonari
authors.initials: T
authors.lastname: Hirano
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kazama
authors.forename: Sumie
authors.initials: S
authors.lastname: Ohbu
authors.forename: Yuki
authors.initials: Y
authors.lastname: Shirakawa
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kambara
authors.forename: Nobuhisa
authors.initials: N
authors.lastname: Fukunishi
authors.forename: Tomoko
authors.initials: T
authors.lastname: Abe
mesh_terms: D017360:Arabidopsis / Q000528:radiation effects*; D001128:Argon; D001483:Base Sequence; D002244:Carbon; D018744:DNA, Plant / Q000235:genetics; D017343:Genes, Plant / Q000528:radiation effects*; D020450:Heavy Ions / Q000009:adverse effects*; D018499:Linear Energy Transfer; D009154:Mutation / Q000528:radiation effects*; D012639:Seeds / Q000235:genetics / Q000528:radiation effects; D017384:Sequence Deletion
chemical_list: D018744:DNA, Plant; D001128:Argon; D002244:Carbon