陆地棉第10染色体衣分、纤维品质性状QTL精细定位及候选基因筛选

Cotton is important nature fiber crop. It is important to fine-map QTL controlling yield and fiber quality traits and to identify QTL candidate genes for molecular assisted selection breeding in cotton. In our previous studies, QTL affecting lint percentage and fiber quality traits were identified on a high maker density region on chromosome 10 in composite cross population((7235 × Yumian 1) ×(cri 35 × Yumian 1 )) and recombinant inbred line population (7235 × Yumian 1) in upland cotton, and the QTL explained more than 10% of trait variances. To find the exact QTL position and identify the markers which are closely linked with QTL, a mapping population with about 3000 individuals is established from a cross between a recombinant line RIL10 and Yumian 1. For RIL10, the QTL region was donated by line 7235, and the other chromosome regions were donated by Yumian 1. SSR markers mapped on chromosome 10 from (RIL10 × Yumian 1) recombinant inbred line population, ET-ISJ, IT-ISJ, SRAP, SSR designed from D genome sequence which responds to the QTL region and SSR designed from upland cotton BAC-ends sequences where the QTL located will be used to construct a saturated QTL region map on chromosome 10. Based on the lint percentage and fiber quality traits identified in (RIL10 × Yumian 1) F2 population, F3 and F4 recombinant lines, the QTL affecting lint percentage and fiber quality traits are fine-mapped. Sequencing will be conducted on the BAC clones where the QTL locates, and the putative QTL candidate genes are confered according the BAC sequences. RT-PCR and QPCR will be used to analyze the expression pattern of putative QTL candidate genes during the different stages of developing fiber. According the result of expression analysis, the QTL candidate genes will be confirmed and cloned.

棉花是最重要的天然纤维作物。精细定位棉花产量、纤维品质QTL和鉴定QTL候选基因对棉花分子标记辅助育种意义重大。本项目前期利用复合杂交群体和重组近交系群体，在第10染色体检测到环境稳定解释性状变异10%以上的衣分、纤维品质QTL。为进一步弄清QTL的准确位置和鉴定与QTL紧密连锁的标记，本项目选择第10染色体QTL区域为7235提供（其它染色体为渝棉1号提供）的株系RIL10与渝棉1号杂交，建立（RIL010×渝棉1号）F2大群体。利用第10染色体上的SSR与ET-ISJ、IT-ISJ、SRAP、QTL区域对应的D基因组SSR和QTL区域陆地棉BAC末端SSR，构建QTL区域饱和遗传图，以F2群体、F3和F4重组系的产量、纤维品质鉴定结果，精细定位第10染色体衣分、纤维品质QTL。随后全测序QTL所在BAC克隆，推测QTL初步候选基因。根据初步候选基因的表达分析结果，确定并克隆候选基因。

棉花是最重要的天然纤维作物。精细定位棉花产量、纤维品质QTL与鉴定QTL候选基因对棉花分子标记辅助育种具有重要意义。实验室前期利用重组近交系群体在陆地棉第10染色体检测到环境稳定解释性状变异10%以上的衣分、纤维品质性状QTL。为进一步精细定位衣分、纤维品质性状QTL，本研究选择第10染色体QTL区域为7235提供（其它染色体区域为渝棉1号提供）的株系RIL179与渝棉1号杂交，建立了（RIL0179×渝棉1号）F2大群体及F2:3重组系群体。利用第10染色体上原有的SSR标记与QTL区域对应的雷蒙德氏棉、亚洲棉和陆地棉基因组序列设计的SSR引物共计3730对，构建了QTL区域高密度遗传图图，以F2群体和F2:3重组系的产量、纤维品质鉴定结果，将第10染色体衣分、纤维品质性状QTL定位到0.37cM的区间内（侧翼标记SWU9011和SWU8326），该区域对应陆地棉A10染色体432kb，包含21个注释基因。表达谱测序和基因序列分析结果表明，ROPGEFs5可能为第10染色体控制纤维发育的目的基因。研究结果为陆地棉分子标记辅助选择育种和棉花纤维发育机制研究奠定基础。