甘蓝型油菜蕾薹期抗旱相关性状的QTL分析

摘要

Bolting is one of the most sensitive stages to drought stress in Brassica napus.To identify quantitative trait loci(QTL)associated with drought resistance at bolting stage,we generated a F2:3populations with 183 lines by crossing drought-resistant line QY8 -1 with the drought-sensitive one Huyou16.This population was subjected to two treatments,namely drought stress from bud emerging to bolting stages and well-water at the same stages.The results showed that shoot height,single plant fresh weight and leaf wilting index were all decreased by 52.6% ~55.3% in av-erage under drought stress compared to the control.Moreover,the three traits were highly positively correlated,indicating that they are suitable drought-resistant indicators.A linkage map was constructed with 335 SRAP markers,covering a total length of 1661.9 cM.By using composite interval mapping method,a total of 28 QTLs were detected across 14 link-age groups(LG),accounting for 1.1% to 36.6% of trait variation.Among these,10 QTLs were identified for shoot height,and the one in LG15(qSH-D-5)was a major QTL accounting for 36.6% of variation.There were three oth-er QTLs(qSH-DRI-1、qSH-D-5 and qLWI-D-1)overlapping this interval,thus being an important genetic re-gion for breeding selection via molecular markers.Meanwhile,there were also 4 minor QTLs overlapping at marker inter-val Em01/Me12-1—Em01Me09-1 in LG16,only accounting for 1.1% ~8.1% of trait variation.%蕾薹期是甘蓝型油菜对干旱最为敏感的时期之一.以抗旱品系QY8-1和干旱敏感品种沪油16构建的含183个家系的F2:3群体为研究材料,在现蕾至抽薹期进行干旱胁迫处理,正常灌溉为对照.结果表明,与对照相比,干旱胁迫后群体的抽薹高度、单株鲜重和叶片萎蔫指数平均下降了52.6% ~55.3%,而且三个指标高度正相关.利用335个SRAP标记构建了一个长度为1661.9 cM的遗传图谱,通过复合区间作图法共检测到28个QTL,分布在14个连锁群上,可解释1.1% ~36.6% 的表型变异.其中,利用抽薹高度共检测到10个QTL,位于第15连锁群的 qSH-D-5可解释36.6% 的表型变异,为主效QTL.该区间还检测到其它3个QTL(qSH-DRI-1、qSH-D-5和 qLWI-D-1),在抗旱分子标记辅助选择中应予以重点关注.同样,在第16连锁群(标记区间Em01/Me12 -1—Em01Me09-1)也检测到4个重合的QTL,贡献率为1.1% ~8.1%,为微效QTL.