Identification and Gene Mapping of Dwarf and Brittle Culm Mutant dbc1 in Oryza sativa

One dwarf and brittle culm mutant dbc1 was identified from the progeny of restorer line Jinhui10 which seeds were treated by ethyl methanesulfonate(EMS).From the seedling stage to the mature stage,dbc1 showed obvious characteristics of dwarfism and frangibility.In detail,the mutant shortened each internode with a plant height of 58.93 cm,belonging to the dn type of dwarfism mutation.Treated by GA 3,the dbc1 showed more insensitive compared with its original parent Jinhui10.One thousand grain weight,seed-setting rate,and tiller numbers did not change while panicle length,grain number per panicle and full grain number decreased significantly in the mutant.Further analysis showed that mechanical strengths declined significantly in the mutational leaf blades and culms.Interestingly,cellulose content was not changed and lignin content slightly decreased compared with those of wild type,with a significant difference at P0.05 between them.Genetic analysis indicated that the mutation was controlled by one recessive nuclear gene.In this paper,DBC1 gene was finally mapped between SSR markers RM13943 and RM13952 on chromosome 2 based on 886 F 2 mutational plants of Xinong1A/dbc1.In the restricted region,the physical distance was 197 kb and contained 52 annotated genes.These results provide a foundation for DBC1 gene cloning and its application in the molecular breeding.