陆地棉第六染色体衣分和纤维品质性状QTL图位克隆与功能分析

Cotton is the most important natural fiber crop. It is significantly important for cotton molecular breeding to map-based clone QTL for yield and fiber quality. With the financial support from the National Science Foundation for Young Scientists of China, the fine mapping populations with 1440 F2 individuals and 4313 F3 individuals were established from a cross between recombinant line RIL118 and Yumian 1. For RIL118, the QTL region on chromosome 6 derived from T586 and the other chromosome regions derived from Yumian 1. The QTL/genes for trichome, lint percentage and fiber quality traits were mapped within a region with 0.20cM on chromosome 6. The SSR markers located on QTL region were used to screen upland cotton BAC clone bank, and 5 positive BAC clones were attained. However, it is still unclear whether the genetic relationship is pleiotropic or polygenic linkage among genes/QTLs for trichome, lint percentage and fiber quality traits on chromosome 6. In order to make clear the genetic relationship among trichome, lint percentage and fiber quality, the present study first map-based clone the candidate genes for trichome, lint percentage and fiber quality traits, and then conduct on analyses including functional complementation, expression and regulation, promoter activity and gene location. The research results will pave a way for studying the molecular mechanism of fiber development and improving cotton variety with molecular breeding methods.

棉花是世界上重要的天然纤维作物。图位克隆棉花产量、纤维性状QTL对棉花分子育种具有重要意义。本项目组在国家自然科学基金青年基金项目资助下，利用陆地棉品种渝棉1号与（T586×渝棉1号）重组近交群体重组系RIL118杂交建立的分别包括1440和4313个单株的F2、F3群体，将第6染色体植株绒毛、衣分以及纤维品质性状QTL/基因定位到0.20cM区域内。随后利用QTL区域SSR标记筛选陆地棉BAC库，获得5个阳性BAC克隆。但第6染色体植株绒毛、衣分和纤维品质性状QTL/基因间是一因多效或多基因连锁的遗传关系仍不清楚。为进一步阐明第6染色体植株绒毛、衣分和纤维品质性状QTL/基因间的遗传关系，本项目在图位克隆候选基因的基础上，通过功能互补、表达调控、启动子活性和基因定位分析，对植株绒毛、衣分、纤维品质性状QTL/基因进行深入研究，为棉花分子育种和纤维发育分子机理研究奠定基础

棉花是最重要的天然纤维作物。克隆和鉴定纤维品质QTL候选基因对棉花分子标记辅助育种意义重大。本项目前期利用重组自交系群体，在第6染色体精细定位到环境稳定的纤维品质性状QTL。为进一步确定QTL候选基因和进行基因功能分析，本项目选择第6染色体来自T586，其他染色体来自渝棉1号的重组系RIL118与渝棉1号杂交建立的次级F2分离群体，将第6染色体纤维品质性状QTL定位到0.28cM内，并利用表达谱测序和qRT-PCR分析鉴定到3个QTL候选基因，克隆比较T586与渝棉1号3个基因的启动子和基因组全长，最终鉴定到有差异的候选基因，构建该基因的超量、抑制和纤维特异表达载体，以及该基因的T586与渝棉1号启动子表达载体转入陆地棉品种冀棉14号，目前已获得超量表达该基因的转基因棉花。