甘蓝型油菜分枝数QTL定位及其候选基因预测

分枝数是影响油菜产量的重要株型性状之一。为了有助于油菜分枝数的分子标记辅助育种,以甘蓝型油菜品系888-5(多分枝)和M083(少分枝)杂交形成的重组自交系(RIL)群体为材料,通过利用第一张油菜60KSNP芯片对群体进行高通量SNP分型,并结合单环境和多环境2种QTL检测方法对RIL群体在4个环境(武汉-2012、武汉-2013、扬州-2012和扬州-2013)下分枝数进行QTL定位。结果表明:共检测出18个分枝数QTL,分布于A2、A6、A7、C1和C4连锁群。其中11个QTL在2个以上环境下可重复检测到;有2个QTL与环境之间存在互作效应。主效QTL 2个(qBN2-3和qBNE2-1),分别在3个、4个环境下重复检测到,可解释的表型变异为13.12%~20.60%,2.80%~30.10%。qBNE2-1与环境存在互作效应。另外,通过利用SNP标记侧翼序列和油菜基因组比对作图,从3个QTL(qBN2-1、qBN7-6和q BN7-8,三者可解释的表型变异分别为19.40%~17.30%、5.70%~12.21%和7.88%~10.32%)的基因组区段内(分别为279kb、165kb和562kb)共筛选出4个与分枝数有关的候选基因,它们的拟南芥同源基因(分别为CUC2、PIN3、F23N20.8和PIN4)均参与拟南芥分枝数的分化或形态建成。

QTL mapping of branch number in Brassica napus and candidate gene prediction

 Branch number is an important trait affecting yield of oilseed rape. To improve breeding efficiency on branch number improvement, QTLs on branch number were identified by using single environment and multi-environment detection methods. The mapping was conducted in a recombinant inbred lines (RILs) population derived from 888-5 (with more branch number) and M083 (with less branch number) by employing newly developed Brassica napus 60K SNP array. Results indicated that a total of 18 putative QTLs in 4 environments (Wuhan-2012, Wuhan-2013, Yangzhou-2012, and Ynagzhou-2013) were found on chromosome A2, A6, A7, C1 and C4. Among them, 11 QTLs were repeatedly detected in more than 2 environments, and 2 QTLs showed interaction with environments. 2 major effect QTLs (qBN2-3 and qBNE2-1) were repeatedly detected in 3 and 4 environments respectively, explaining 13.12%-20.60% and 2.80%-30.10% of phenotypic variations. QTL qBNE2-1 presented interaction with environment. By comparative mapping of the SNPs flank sequences with B. napus genome, 4 candidate genes were found from genomic regions (279kb, 165kb and 562kb) of 3 QTLs (qBN2-1, qBN7-6, and qBN7-8 which explained 19.40%-17.30%, 5.70%-12.21%, and 7.88%-10.32% of phenotypic variations respectively). Their orthologous genes in A. thaliana were CUC2, PIN3, F23N20.8 and PIN4, all involving in branch number differentiation in A. thaliana.