Chlorophyll-deficient mutants of rice demonstrated the deletion of a DNA fragment by heavy-ion irradiation.

Heavy-ion irradiation is a new method of mutation breeding to produce new cultivars. We established the application of this method in rice plants to obtain mutants. Rice seeds were irradiated by C or Ne ions (135MeV/u) with a LET (linear energy transfer) of 22.7 or 64.2 keV/microm, respectively. Chlorophyll-deficient mutants (CDM) segregated in M2 progeny were albino, pale-green, yellow or striped-leave phenotypes. The highest rate of CDM with C-ion irradiation, 7.31%, was obtained at 40 Gy among the doses examined. Ne-ion irradiation gave the highest rate, 11.6%, at 20 Gy. We used the RLGS (Restriction Landmark Genomic Scanning) method to analyze DNA deletion in an albino mutant genome. Not I-landmark RLGS profiles detected about 2000 spots in rice. We found that one of the polymorphic spots was strongly linked to the albino phenotypic mutant derived from deleting of a DNA fragment, and demonstrated the high ability to detect of polymorphic regions by the RLGS method.