利用BC_3F_1群体定位和分析甘蓝型油菜A7-含油量QTL

Mapping and Analysis of an Oil Content QTL in the Linkage Group 7 Using BC_3F_1 Population of Brassica napus

【目的】通过构建BC3F1群体对第7连锁群上一个影响油菜籽油分含量的主效QTL(A7-QTL)进行定位确认。【方法】在用SG-DH群体初定位基础上以欧洲品种Sollux为轮回亲本、目标区段含中国亲本Gaoyou等位基因片段的DH系为供体构建近等基因系。用1700个BC3F1单株基因型和其种子(BC3F2)表现型,采用WinQTLCartographer2.5和SPSS11.5软件对A7-QTL进行精细定位以及标记和性状的关联分析。【结果】含油量QTL的置信区间在标记ZAAS849s-R131之间,范围在21.7cM左右,其LOD峰值为9.71,距离两侧最近标记RPSaA3和ZAAS839分别为0.9和2.1cM,QTL的加性效应值是0.75;QTL区段内的单标记方差分析表明:目标区段内4个标记各3种基因型的含油量之间存在极显著差异,标记ZAAS839处的差异最显著(P=1.2×10-10);通过比较含油量和4个标记之间的对应关系,进一步推断QTL最可能位于标记RPSaA3和ZAAS839之间或临近。【结论】用BC3F1群体定位的QTL区间与DH群体分析结果相重叠,但置信区间明显缩小;定位结果进一步确认了A7连锁群上存在油分QTL的真实性,增加了在该区域存有参与控制油菜含油量基因的可靠性;QTL可能存在于标记RPSaA3和ZAAS839临近区域,两标记间距约3cM。

【Objective】 Mapping and conforming a major QTL for oil content in linkage group 7 using BC3F1 population in Brassica napus L. 【Method】 QTL-near isogenic lines （NILs） were developed by marker assistant selection on the basis of primary QTL analysis with SG-DH lines. 1700 BC3F1 plants,containing corresponding marker genotypes on A7 and trait phenotypes of oil content,were used for fine mapping oil QTL and association analysis between the marker genotypes and the trait （oil content） performance on A7 by software WinQTLCartographer 2.5 and SPSS11.5. 【Result】 The confidence interval of oil content QTL was located between the markers ZAAS849s and R131,which range about 21.7 cM and the peak value of LOD was 9.71. The distances between QTL and the nearest flanking markers RPSaA3 and ZAAS839 were 0.9 and 2.1 cM,respectively. The additive effect of QTL was 0.75,with Chinese allele increasing oil content. Marker-oil content association analysis （ANOVA） indicated that the oil content showed a significant difference among the three types of marker genotypes in each loci within QTL region （four markers）,of which the marker ZAAS839 showed the largest P value （P=1.2×10^-10）. 【Conclusion】 QTL position identified by mapping analysis using BC3F1 population was overlapped with primary QTL identification using SG-DH lines,however,the confidence interval was clearly decreased. The most probable QTL position is in the region near the markers RPSaA3 and ZAAS839. The genetic distance between RPSaA3 and ZAAS839 is about 3 cM.