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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。
One friable mutant was obtained from the F2 population of three cross combinations Ⅱ-32B // Xieqingzao B / Dular, and the whole plant showed full-fledged fragility. Based on the phenotype of this mutant, it was named Bc18 (Brittle culm 18). In order to better identify the mutant, Bc18 crispbred near-isogenic line Bc18 and Bc18 were created by crossbreeding with 9B in the normal stem intensity cultivar. The phenotypic identification showed that there was no significant difference in the main agronomic and yield traits of mutant Bc18 between the wild type and B9 in the growth stage, plant height, number of panicle per plant, grain number per spike, seed setting rate and grain weight per plant, Mechanical strength decreased by 70.70% and 47.16% respectively. Analysis of cell wall components showed that the content of cellulose and lignin in stem and leaves of mutant Bc18 was not significantly different from that of wild type 9B, but the content of hemicellulose increased by 31.84% and 17.35% respectively. Genetic analysis of 6 crosses F2 and 12 backcross BC1F1 populations demonstrated that the Bc18 fragile mutation is controlled by a dominant-dominant gene. The F2 locus population of Bc18 / 02428 and Bc18 / 9311 was constructed by using map-based cloning technique. Finally, the Bc18 gene was mapped on InDel-tagged PBC22 on chromosome 1 using the published SSR marker and the newly designed InDel marker PBC33 between the interval of about 154kb.