多叶型三叶草分子遗传图谱的构建及其QTL定位

Caucasian clover and white clover are both excellent perennial legumes. Fertile hybrids that with both parental traits can be obtained through interspecific hybridization. Multifoliate trait is one of the important factors that affect the quality of clover, studying and exploring the gene associated with multifoliate trait is the effective way to improve the quality of clover. Based on the previous research work, the hybrids F1 with multifoliate trait were successfully obtained by distant hybridization using multifoliate white clover as male parent and Caucasian clover as female parent. Due to the characteristic of high pollen fertility of hybrids F1, the hybrids F2 population with rich character separation were then obtained through self-crossing. The SSR markers of the hybrids were also developed by RNA-Seq. In this study, SSR will be used to construct molecular genetic map by using hybrids F2 as the mapping population, and the QTLs of multifoliate trait will be located combining with observation of multifoliate trait in hybrids F2. The results will provide important theoretical significance and application value in revealing the mechanism of multifoliate trait and breeding high quality varieties of clover.

高加索三叶草与白三叶均为豆科多年生优良牧草，通过远缘杂交可以获得结合二者优势的可育杂种后代。多叶性状是影响三叶草品质的重要因素之一，研究及发掘多叶性状的相关基因是培育高品质三叶草新品种的有效途径。申请人在前期的研究工作中，以多叶型白三叶为父本、高加索三叶草为母本进行杂交，成功获得了二者的多叶型杂种F1代。并利用杂种F1育性较高的特点，自交得到了性状分离丰富的杂种F2代群体。同时通过转录组测序技术开发了此杂种后代的SSR标记。本项目拟以多叶型白三叶与高加索三叶草的杂种F2代为作图群体，利用SSR分子标记技术，构建遗传连锁图谱，并结合其叶片表型两年两点的观测数据，对多叶性状进行QTL定位分析，确定控制三叶草多叶性状的主效QTL。本研究结果对深入揭示三叶草多叶性状的形成机理以及高品质三叶草新品种的选育具有重要的理论意义和实际应用价值。

多叶性状是影响三叶草品质的重要因素之一，研究及发掘多叶性状的相关基因是培育高品质三叶草新品种的有效途径。本项目以多叶型白三叶与高加索三叶草的杂种F2代为作图群体，利用SSR分子标记技术，构建遗传连锁图谱，并结合其叶片表型两年两点的观测数据，对多叶性状进行QTL定位分析，确定控制三叶草多叶性状的主效QTL。研究发现，242对SSR标记构建出一张含有14个连锁群的遗传图谱。该图谱全长为1221cM，各连锁群的长度范围在53.3cM-101.4cM之间，平均长度为76.05cM，以连锁群LG2最长，LG11最短。图谱共包含983个SSR标记位点。各连锁群的标记数以LG4最多，为105个，LG9最少，为33个，平均70个；各连锁群标记间平均距离在1.6cM-4.9cM之间，平均距离3.1cM。应用区间作图法对三叶草多叶性状基因进行QTL分析定位，共检测到9个相关QTL位点，分别位于LG2、LG4、LG5、LG8、LG10、LG12和LG13上，所有显著性QTL位点表型贡献率的变化范围为8.36%-19.15%。