水稻显性脆秆突变体Bc18的鉴定和基因定位

Characterization and Gene Mapping of a Dominant Brittle Culm Mutant Bc18 in Rice(Oryza sativa L.)

从三交组合Ⅱ-32B//协青早B/Dular的F2群体中获得了1个脆性突变体,整个植株表现全生育期脆性。根据该突变体的表型,将其命名为Bc18(Brittle culm 18)。为了更好地鉴定该突变体,用正常茎秆强度品种中9B作轮回亲本与Bc18杂交,创制了Bc18脆秆近等基因系中脆B和中9B。表型鉴定显示,突变体Bc18在生育期、株高、单株穗数、每穗粒数、结实率和千粒重等主要农艺和产量性状上与野生型中9B无显著差别,但茎、叶的机械强度分别下降了70.70%和47.16%。细胞壁组分分析表明,突变体Bc18茎、叶的纤维素和木质素含量与野生型中9B无显著差异,但半纤维素含量分别提高了31.84%和17.35%。6个杂交组合F2和12个回交BC1F1群体的遗传分析证明Bc18脆性突变由单显性基因控制。采用图位克隆技术,构建了Bc18/02428和Bc18/9311的F2定位群体,并利用网上公布的SSR标记和新设计的InDel标记,最终将Bc18基因定位在第1染色体长臂端InDel标记PBC22与PBC33之间约154kb的区间内。

A brittle culm mutant was obtained from the F2 population of three-way crossⅡ-32B//Xieqingzao B/Dular and named as Brittle culm 18(Bc18)according to its phenotypes.Each part of plant showed brittleness during the whole growth period.In order to identify the mutant,near isogenic line populations of Zhongcui B and Zhong 9Bwere created with Bc18 mutant as the donor of brittle gene and Zhong 9B,a normal culm-strength variety,as the receptor and recurrent parent.Compared with wild type,Bc18 significantly declined by 70.70% and 47.16% in mechanical strength of culm and leaves,respectively.No significant differences were found in terms of growth duration,plant height,panicle number per plant,spikelet number per panicle,seed setting rate and 1000-grain weight.Cell wall components analyses showed that cellulose content and lignin content in Bc18 had no significant difference as compared with those of wild type,while hemicellulose content in culm and leaf dramatically increased by 31.84% and 17.35%,respectively.Genetic analyses of six F2 and twelve BC1F1 backcross populations revealed that the phenotype of Bc18 was controlled by a single dominant gene.Bc18/02428 and Bc18/9311F2 populations were developed for Bc18 gene mapping.By means of map-based cloning technology,with some SSR markers published online and new designed InDel markers,Bc18 was localized between InDel marker PBC22 and PBC33at a physical distance of about 154 kb on the long arm of chromosome 1.This work laid the foundation for cloning Bc18 gene in the future.