基于全基因组关联分析的向日葵苗期抗旱相关性状基因/QTL解析

Carrying out the research on the QTL mapping related to drought-tolerance and exploring elite alleles are the prerequisite and foundation of improve drought resistance traits efficiently by using molecular markers breeding, which will have great scientific significance to cultivate sunflower High yield and drought-resistance varieties. A genetic map consisting of 17 linkage groups had been constructed with 1105 loci (368 SSR, 369 SRAP, 333 AFLP) which covers 3846.0 cM by our project team，and QTL analysis of 19 traits related to drought tolerance had been conducted in recombinant inbred lines(RIL). On the basis of that, we will use 260 sunflower inbred lines which have a large difference in genetic background as association mapping group. SNP markers will be developed by the SLAF-Seq approach, then genome-wide scanned by SNP markers and SSR markers, combining with the seedling drought-resistance related phenotypic identification under water and drought conditions, through association analysis of marker-type based on linkage disequilibrium (LD), many aims could be realized: validate these QTLs; QTLs fine map; Explore drought resistance candidate genes; the elite alleles of tolerance to drought along with their carriers could be detected too. The conclusion could establish an important theoretic ground to reveal the sunflower drought resistance molecular genetic mechanisms and molecular breeding for favorable genes related to drought tolerance in sunflower.

抗（耐）旱相关性状QTL定位和优异基因的发掘研究，是运用分子育种对抗旱性状进行高效改良的前提和基础，对我国向日葵高产抗旱新品种创新具有重要科学意义。项目组已构建完成了长度3846.0cM分布有1105个标记(368个SSR、368个SRAP和369个AFLP)的向日葵高密度遗传连锁图谱，并通过连锁分析对19个抗旱相关性状进行了QTL定位。在此基础上，260余份（122份已完成SLAF测序）来源不同的向日葵自交系种质材料为关联群体，控制灌水条件下进行苗期各抗旱相关性状的表型鉴定，SLAF-Seg技术开发SNP标记，SNP标记结合SSR标记技术进行全基因组扫描，通过基于连锁不平衡的标记-表型关联分析，实现抗旱性状QTL的验证及其精细定位，生物信息学分析技术挖掘抗旱候选基因，同时发掘抗旱相关性状的优异等位基因及载体种质，为向日葵抗旱性分子遗传机制的揭示及抗旱性分子设计育种奠定重要理论基础。

干旱已成为世界范围内影响作物生长发育和降低产质量的主要非生物胁迫因素之一。围绕作物抗旱性的深入研究目前受到世界各国科学工作者的高度重视。抗（耐）旱相关性状QTL定位和优异基因的发掘研究，是运用分子育种对抗旱性状进行高效改良的前提和基础，对我国向日葵高产抗旱新品种创新具有重要科学意义。本项目以226份向日葵种质为关联群体，控制灌水条件下进行苗期抗旱相关性状的表型鉴定，筛选出极耐旱种质材料3份，耐旱种质材料12份。通过简化基因组测序（SLAF-Seg）开发了2,124,143个有效SNP标记，与向日葵苗期抗旱相关的根冠比、根长、根表面积、根体积、株高、叶片相对含水量、SPAD值、叶面积等8个性状进行关联分析，检测到16个显著关联的SNP位点和22个候选基因，与转录组数据联合分析筛选出向日葵苗期抗旱相关候选基因13条，基因功能主要富集在脱落酸（ABA）合成及其信号传导途径。项目研究结果将为向日葵抗旱性分子设计育种提供重要科学依据。