大豆耐荫重要性状QTL分析及候选基因挖掘

The relay strip intercropping could expand planting area, increase production, and alleviate the domestic imbalance between supply and demand in soybean. However, soybean was suffered from different extent of shade stress by taller crops, which limited seriously soybean production and mechanized harvesting. Previous researches have indicated that soybean differed in shade tolerance among different genotypes, and a genotype with high shade tolerance (Nandou12) was obtained from 568 soybean germplasm resources in southwest China. Two populations of recombinant inbred lines (RILs) were developed between Nandou12 and two different cultivars with low shade tolerance. Up to now, the genetic mechanism of shade tolerance is unclear, and high and stable yield varieties are scarely in relay strip intercropping. So, in present study, QTL mapping for shade tolerance characteristics in RILs derived from Nandou12 and Jiuyuehuang will be analyzed during four growth stages. The major QTL for great phenotypic variance will be validated by using the RILs derived from Nandou12 and C103. According to the bioinformatics analysis, the candidate genes involved in shade tolerance were discovered among these loci, and their sequence alignments were analyzed to find the sequence differences between both parents Nsndou12 and Jiuyuehuang. Moreover, their linkage analyses were also conducted using the primers in the RIL population. Additionally, the spatial and temporal expression of candidate genes was detected to discover their relationship with shade tolerance by qPCR. The research could be used in marker assisted selection in breeding, and reveal genetic mechanisms of high shade tolerance in soybean.

带状间套作是扩大大豆种植面积和提高总产量的重要途径，对缓解我国大豆供需矛盾具有重要意义。然而在间套作过程中，大豆会遭受不同程度的荫蔽胁迫，严重影响产量和机械化收获。为此，本课题将针对大豆耐荫性的遗传机制尚不明确的科学问题以及我国带状套作大豆生产对耐荫高产稳产的大豆品种迫切需要的现状，基于西南地区丰富的耐荫大豆种质资源，拟以净作为对照，在带状套作下，利用RIL群体南豆12/九月黄，结合前期构建的基于SSR和SNP标记的高密度遗传图谱，进行4个生育时期的荫蔽重要性状QTL分析，并利用RIL群体南豆12/C103，对表型变异度大的主效QTL进行验证，采用生物信息学方法，挖掘与耐荫相关的候选基因，利用qRT-PCR技术分析作图群体亲本在不同时空的表达情况，并通过测序和比较分析进一步确定重要候选基因，为分子标记辅助选择提供依据，揭示大豆耐荫性遗传机理。

带状间套作是扩大大豆种植面积和提高总产量的重要途径，对缓解我国大豆供需矛盾具有重要意义。然而在间套作过程中，大豆会遭受不同程度的荫蔽胁迫，严重影响产量和机械化收获。为此，本课题将针对大豆耐荫性的遗传机制尚不明确的科学问题以及我国带状套作大豆生产对耐荫高产稳产的大豆品种迫切需要的现状，基于西南地区丰富的耐荫大豆种质资源，拟以净作为对照，在带状套作下，利用RIL群体南豆12/九月黄，结合前期构建的基于SSR和SNP标记的高密度遗传图谱，进行4个生育时期的荫蔽重要性状QTL分析，并利用RIL群体南豆12/C103，对表型变异度大的主效QTL进行验证，采用生物信息学方法，挖掘与耐荫相关的候选基因。主要结果如下：2个RIL群体的茎秆相关性状在净套作下变幅范围广，超亲分离普遍存在，各性状分布表现出数量性状典型的连续变异。采用ICImapping 4.0软件，利用完备区间作图法（ICIM）共检测到144个QTL位点。在净作下总共检测到79个QTL，在套作下总共检测到62个，控制耐荫系数的QTL3个。在检测到的QTL位点中，贡献率高于15%的有7个，主要在净作下检测到，分布在Chr4和Chr19。根据检测到的主要QTL位点设计了66个分子标记，其中23个KASP和16对SSR标记可以在南豆12和九月黄分型，4个KASP和12个SSR标记可以在南豆12和C103分型。与表型性状分析表明6个标记可用于株高的分子标记选择。该结果可为大豆分子标记辅助育种奠定基础。根据大豆基因组信息，筛选出3个候选基因，在耐荫材料南豆12在不同光照环境下表达量差异均达到极显著。对南豆12在不同光照下的株高及激素的分析表明，相对于正常光照，大豆株高在其他光照环境下显著升高；激素IAA和GA1在不同光照环境下显著降低。