Rapeseed oil is a major edible oil source for human consumption. Its quality depends on its fatty acid composition. Among fatty acids, 18-C unsaturated fatty acids are most crucial. QTL mapping will pave a way for molecular breeding and cloning genes for fatty acid biosynthesis in rapeseed. In this study, the zero-erucic rapeseed parents HOP (high oleic) and Xiangyou 15 (low oleic) were used to construct a F2 population consisting of 189 individual plants. The construction of a genetic map containing 342 SSR markers and the mapping of QTLs for the 18-C unsaturated fatty acid contents were carried out. Two sampling methods, I.e., half-seed sampling from F2 single seeds and bulk-seed sampling from F2 individual plants (F3 seeds), were used to determine the fatty acid contents by gas chromatography. The correlations of the fatty acid contents between the two sampling methods as well as most of the correlations between these fatty acids were significant. Totally two major QTLs for oleic acid content were detected in the linkage groups (LG) of A5 and C5, which could explain 60~70% of the variance for oleic acid content. The superior one of the two QTLs was mapped in LG A5 and tightly linked to the FAD2 gene. The other one which located in LG C5 was a major QTL newly found for oleic acid content. The marker closest to this QTL was found to be homologous to the marker on the LG A5, implying the QTL on C5 was also associated with the FAD2 gene. Consistent effect of the two QTLs was confirmed using oleic acid contents determined by the two sampling methods. The QTLs for oleic acid content was found to be the ones for the linoleic acid content, which was consistent with the high significant correlation between the two fatty acids. Nevertheless, one more minor QTL for linoleic acid content with a low LOD value was shown on LG A4 using the bulk-seed method. For linolenic acid content, three major QTLs on LG A4, A5, and C4, respectively, were detected consistently using the determinadons of the two sampling methods, totally explaining 72-80% of the variance for linolenic acid content. Furthermore, another QTL with a low LOD value, only accounting for 12.42% of variance was detected on LG A4 using the half-seed method.%用无芥酸的高油酸油菜品系HOP和低油酸油菜品种湘油15为父母本构建含189单株的F2代作图群体.F2代单粒种子播种前采用半粒取样,F2代单株种子采用混合取样,进行脂肪酸含量的气相色谱分析.统计检测显示,这两种方法测定结果极显著相关,各种脂肪酸含量之间大部分也呈显著相关.用该群体构建含342个SSR标记的遗传连锁图并对18碳不饱和脂肪酸含量进行了QTL定位.在A5和C5连锁群上各检测到1个油酸含量主效QTL,其中位于A5连锁群的QTL效应值较大,且与FAD2基因紧密连锁;位于C5连锁群的QTL为首次报道,与之紧密连锁的标记在A5连锁群QTL区域有同源标记,说明可能与位于C5的FAD2基因有关.用两种方法测定性状值都能检测到这2个QTL,且效应值比较接近,共能解释60%～70%油酸含量变异.由于油酸含量与亚油酸之间高度相关,定位在A5和C5的油酸含量QTL也被确认为亚油酸含量主效QTL,但利用单株法测定的性状值能在A4连锁群上再发现1个LOD值较低的亚油酸含量QTL.两种测定法能比较一致地在A4、A5和C4连锁群上检测到3个亚麻酸含量主效QTL,共能解释72%～80%亚麻酸含量变异.用半粒法能在A4连锁群还能检测到1个解释变异度为12.42%的较小LOD值的亚麻酸含量QTL.
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