甘蓝型油菜分枝数QTL定位及其候选基因预测

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

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QTL2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qBN7-8,三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.

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 60 K 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( q BN2- 3 and q BNE2- 1) were repeatedly detected in 3 and 4 environments respectively,explaining 13. 12%- 20. 60% and 2. 80%- 30. 10% of phenotypic variations. QTL q BNE2- 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( 279 kb,165kb and 562kb) of 3 QTLs( q BN2-1,q BN7-6,and q BN7-8 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.