红麻高密度遗传连锁图谱构建及纤维支数QTL定位

Kenaf fiber is an important row material in textile industry. To satisfy the requirements of textile industry development, fiber fineness improvement has become a key task for kenaf breeding. Marker-Assisted Selection（MAS）can speed up process of fiber fineness improvement effectively.However,so far, marker-assisted selection for fiber fineness is still stagnant because of a lack of molecular markers related to fineness alleles.In our previous study, the genetic linkage map has been constructed by using of F2 population, and the QTL related fineness were mapped. But, due to the low density markers in the genetic map, and the population limitation, QTL were not been confirmed across multiple years and at the multiple locations.To overcome these defects, in this study, high-density genetic linkage map will be constructed using the RIL population by the reduced-representation sequencing technology, and the fineness of the RIL population will be surveyed across three years; Then, the QTL mapping will be performed by the linkage analysis and the molecular marker linked fiber fineness closely will be obtained . Those results will lay the foundation for molecular breeding in kenaf. Additionally, the newly-constructed high-density genetic linkage map, characterized by higher dense and novel markers and DNA sequences assembled, can promote the study on marker-assisted selection, candidate gene cloning, and comparative genomics of kenaf in the future.

红麻作为重要的纺织原料作物，提高现有品种纤维支数是育种的重要任务之一。通过分子标记辅助选择可有效加速其改良进程，但目前纤维支数连锁分子标记缺乏。我们前期利用F2临时群体进行了红麻遗传连锁图谱的构建及纤维支数的QTL定位，但构建的遗传图谱连锁的分子标记较少(128个），而且定位的群体为临时群体，QTL结果无法多年多点验证。为了克服以上不足，本研究拟利用我们已经构建的重组自交系群体为作图群体，首先通过简化基因组测序技术构建高密度遗传连锁图谱，同时获得该群体三年一点的纤维支数数据，然后通过连锁分析进行纤维支数QTL定位，最后得到纤维支数紧密连锁分子标记。研究结果可奠定分子辅助选择育种基础。另外，构建的高密度连锁图谱具有分子标记密度高、类型新颖、有序列信息等创新技术优势，将推动红麻分子标记辅助选择、候选基因克隆和比较基因组学研究。

为了进一步提高红麻纤维的产量和质量，本研究以泰红763为母本，F71为父本进行杂交，杂交后代进行单株自交，获得F2:3株系群体。采用RAD-seq技术，利用EcoRI限制性内切酶对父母本和154个F2:3株系的基因组DNA进行酶切，构建RAD测序文库，利用HiSeq4000测序平台进行高通量测序并获得多态性的SNP分子标记。利用Stacks软件对SNP分子标记进行基因分型，利用Joinmap软件和MapChart2.2软件构建并绘制红麻高密度遗传连锁图谱，同时结合纤维产量和质量农艺性状进行QTL定位。测序获得297.5G的clean data，通过对SNP分子标记的筛选和鉴定，最后将1997个多态性SNP标记成功定位于18个连锁群。通过MQM模式定位到6个与纤维产量和质量密切相关的QTL位点，分别是株高、鲜皮重、干皮重、纤维重、纤维强度、纤维支数。这是在红麻中首次基于高密度遗传连锁图谱对纤维产量和质量相关农艺性状进行的QTL定位，为红麻的遗传研究和分子标记辅助育种奠定基础。