水稻矮秆脆性突变体dbc1的鉴定与基因定位

利用EMS诱变籼型水稻恢复系缙恢10号，获得一个稳定遗传的矮化脆性突变体dbc1，苗期即表现矮化、叶片变脆，一直保持到成熟。与原始亲本相比，突变体的各节间均显著缩短，株高仅58.93 cm，略有包穗，属于dn型矮化变异，对赤霉素的敏感性显著下降，有效穗、千粒重和结实率无明显变化，穗长、穗粒数和实粒数则极显著下降。进一步分析发现，dbc1的茎秆和叶片的载荷强度极显著下降，纤维素含量无变化，木质素含量则略有下降，差异达显著水平。遗传分析表明该性状受1对隐性核基因调控，利用886株西农1A/dbc1的F₂变异单株，最终把DBC1基因定位在第2染色体SSR标记RM13943和RM13952之间，物理距离仅197 kb，含有52个注释基因。这为下一步调控基因的克隆和dbc1材料的育种应用奠定了基础。

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 mutantshortened each internode with a plant height of 58.93 cm, belonging to the dn type of dwarfism mutation. Treated by GA₃, 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 P<0.05 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 F₂ 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.