棉花深棕色纤维基因Lc_1的遗传定位

Genetic Mapping of the Dark Brown Fiber Lc_1 Gene in Tetraploid Cotton

【目的】研究棉花棕色纤维的遗传规律,寻找并定位与棕色纤维基因连锁的分子标记,为进一步在棉花基因组学水平上定位、克隆棕色纤维基因和棕色棉纤维品质改良奠定基础。【方法】基于陆地棉显性多基因标记系T586(具有深棕色纤维基因Lc1)与海岛棉新海16配制的海岛棉×陆地棉杂交F2群体,结合色彩色差仪对棕色纤维色泽的分类进行分析,并充分利用棉花基因组分子标记遗传连锁图谱信息、多态性分子标记筛选和图位克隆的方法,定位与棕色棉纤维基因Lc1连锁的分子标记。【结果】根据T586与新海16杂交后代F2群体(443个有效纤维单株)深棕色纤维、棕色(中间色)和洁白色纤维的分离比例,将Lc1定位于棉花基因组A亚组第7染色体微卫星标记NAU4030和CGR5119之间约8 cM的遗传距离内,其中,Lc1与标记CGR5119的遗传距离约为2.8 cM,与NAU4030之间的遗传交换距离约为5.1 cM,构建了Lc1位点的遗传连锁图谱。【结论】棉花深棕色纤维性状由单基因控制并呈现半显性遗传方式,Lc1位点附近的分子标记信息可在棕色棉分子标记辅助育种中得以利用。

[ Objective ] The objective of the experiment is to study and understand the genetic law of brown cotton fiber, to find and locate the molecular markers linked with the locus of brown fiber gene for laying a foundation for fine-mapping, molecular cloning of the brown fiber gene and brown fiber quality improvement at the cotton genome level. [Method] Based on the upland cotton dominant multi-gene markers Line T586 （possesses the dark brown fiber gene LC1） crossing with the sea island cotton Xinhai 16, the F2 population were constructed. Combined with fiber color classification and analysis by colorimeter, taking full advantage of the molecular marker genetic linkage map information of the cotton genome, the molecular markers tightly linked with the dark brown fiber LCl gene were mapped by screening of the polymorphism molecular markers and map-based cloning method. [Result] The F2 population of T586 crossing with Xinhai 16 were composed of 443 individuals, which of them were classified into the dark brown fiber, brown （middle color） and white by the fiber color. Finally, the LC1 was located in the A subgroup of the cotton genome chromosome 7, which was flanked by the SSR marker NAU4030 and CGR5119 with a genetic distance of 8 cM, corresponding to the genetic distance of 5.1 cM and 2.8 cM, respectively. [ Conclusion ] The trait of dark brown fiber is controlled by single gene, possesses the semi-dominant inheritance in tetraploid cotton. The information of molecular markers tightly linked with Lc1 locus could be used in marker-assisted selection in brown fiber cotton breeding.