白芝麻籽粒油脂、蛋白质及芝麻素含量QTL定位分析

QTL Mapping for Oil, Protein and Sesamin Contents in Seeds of White Sesame

芝麻籽粒油脂、蛋白质和芝麻素含量是芝麻品质育种的3个重要目标。为了解析其遗传机制并检测相关QTL,利用近红外谷物品质分析仪对一个包含224个株系的F9代重组自交系(RIL)群体在2年3个环境下的籽粒品质性状检测,结果表明,群体内株系间差异显著且呈典型正态分布,而同一环境不同重复间表现差异不显著。相关性分析显示,籽粒含油量与蛋白质含量显著负相关,籽粒含油量与芝麻素含量显著正相关,蛋白质含量与芝麻素含量显著负相关;利用该RIL群体已构建的高密度遗传图谱,采用基于混合线性模型的复合区间作图法(MCIM)检测到8个QTL,表型贡献率为0.41%~14.55%;采用多重区间作图法(MIM)检测到13个QTL,可解释5.2%~18.6%的表型变异。其中5个主效QTL被2种方法同时检测到且定位区间相同,2个主效QTL在2个或3个环境中被重复检测到。控制含油量的Qoc-5与芝麻素含量的Qsc-5位于LG5连锁群上的相同区段,加性效应均为正值;而控制蛋白质含量的Qpc-5也位于相邻位置,但加性效应为负值。LG2和LG1连锁群上也存在相似情况,反映品质性状相关QTL之间存在一因多效或紧密连锁。因此,在芝麻品质育种中选择高含油量可以兼顾高芝麻素,但应对蛋白质含量进行负向选择。

Seed oil content, protein content and sesamin content are three important targets for sesame breeding. The objective ofthis study was to explore the genetic model and detect quantitative trait loci （QTLs） for three quality traits using a mapping populationcontaining 224 recombinant inbred lines （RILs, F9）. The three quality traits of seeds were measured by near infrared reflectancespectroscopy in three environments. Correlation analysis showed oil content was negatively correlated with protein contentbut positively correlated with sesamin content, whereas, protein content was negatively correlated with sesamin content. Usingmixed composite interval mapping （MCIM） method, eight QTLs for the three seed quality traits were detected with heritability ofadditive effect ranging from 0.41% to 14.55%. Using multiple interval mapping （MIM） method, 13 QTLs were mapped on ninelinkage groups （LGs）, and a single QTL explained 5.2%–18.6% of the total phenotypic variation. Among them, five loci had atleast one marker identical to the QTL identified with MCIM, indicating they might be located in the same region. Two QTLs weredetected in multiple environments. QTLs Qoc-5 and Qsc-5 were located in the same region on LG5, both had positive effects,whereas Qpc-5 in the adjacent region had a negative effect. Similar loci exist on LG2 and LG1, probably caused by pleiotropismor close linkage of several QTLs. These results suggest that the oil and sesamin contents in seed can be improved together, whilethe protein content needs to be selected negatively with the oil or sesamin content.