EFFECTS OF ION BEAM IRRADIATION ON MUTATION INDUCTION IN RICE.

Abstract

Heavy- ion beam irradiation is an effective technique for mutation breeding to produce new cultivars. We evaluated the conditions of heavy-ion beam irradiation on mutation induction in rice (Oryza sativa L.). Rice seeds were irradiated by C or Ne ions accelerated to 135MeV/u within a dose range of 10 to 400 Gy. The LET (linear energy transfer) range of the C-ion beam was 23 to 100keV/μm and that of the Ne-ion beam was 60 to 100keV/μm. To evaluate the effect of irradiation, survival rate and the seed fertility were examined in M1 plants and the frequency of chlorophyll deficient mutants (CDM) was examined in M2 plants. The conditions of C-ion and Ne-ion irradiation to maintain high survival rate were up to 20Gy with 23-40keV/μm, and up to 10Gy with 60-80 keV/μm, respectively. Seed fertility tended to be unaffected by LET values of 23-70 keV/μm with the same dose of irradiation. The highest frequency of CDM was observed in 10Gy at C or Ne ion irradiation with 60-70 keV/μm. In this study, we isolated several mutant lines such as salt-tolerant, bronzing, crinkled-dwarf, necrosis and chlorosis. These mutants could be important as genetic resources for research in plant functional genomics.