大豆鲜荚籽粒上位性QTL及其互作效应分析

荚粒是大豆主要的收获器官，直接影响鲜食大豆品种审定和产品出口。然而，荚粒性状由多基因控制，目前主要集中在加性数量性状位点（quantitative trait loci，QTL）发掘方面，对上位性QTL及其互作效应报道甚少。鉴于此，通过鉴定大豆重组自交系（recombinant inbred line，RIL）群体2年4种环境条件下鲜荚和籽粒的长度、宽度、重量等相关性状，发掘控制其上位性QTLs，并研究其互作效应，结果发现，8种测试性状共检测到321对“加性×加性”上位性QTLs，涉及所有染色体，构成复杂的上位性QTLs互作网络，其中包括144对正向效应和177对负向效应QTLs，并以13号染色体分布数量最多；进一步分析发现，存在34对“一因多效”加性×加性上位性QTLs，且加性×加性上位性QTLs间的互作贡献率为1.89%~4.85%，高于其与环境互作贡献率，说明遗传因素为主；上述34对QTLs涉及18条染色体，其中包含定位区间一致的23对“一因多效”QTLs，并有6组上位性QTLs以“一对多”方式发挥功能，16组以“一对一”方式发挥作用。上述结果不仅为实现大豆荚粒性状精准分子遗传改良提供了选择标记，并为进一步揭示大豆荚粒性状分子遗传机制提供了依据。

Analysis of Epistasis QTL and Its Interaction Effects on Controlling Fresh Pod and Seed Related Traits in Soybean

Soybeans pod and seed are the most important harvested organs in soybean, which not only directly affect the formation of yield and quality, but also play important roles in fresh variety registration and product export. However, the pod and seed related traits are controlled by multiple minor-effect genes, and the related studies mostly focus on the mining of single additive quantitative trait loci (QTL), while very few researches focus on the epistatic QTLs and their interaction effects. In view of this, eight fresh pod and seed related traits of soybean recombinant inbred line (RIL) population including their length, width and weight etc. were analyzed under four different environments, and the epistatic QTLs and their interaction effects were analyzed in this study. The results showed that there were 321 pairs of ‘additive × additive’ epistatic QTLs detected to associate with these eight related traits, which located on all of the soybean chromosomes, and formed a relative complex epistatic QTLs interaction network. Among these epistatic QTLs, 144 pairs showed positive effects, while 177 pairs showed negative effects, and chromosome 13 had the most quantities of epistatic QTLs. Further analysis revealed that 34 pairs of ‘additive × additive’ epistatic QTLs with pleiotropism effects were identified, and the phenotypic variation explanation (PVE) of ‘additive×additive’ QTLs ranged from 1.89%~4.85%, which were higher than the PVEs of QTLs × environments, and indicated that the genetic factors played the main roles. These 34 pairs of ‘additive × additive’ QTLs were located on 18 chromosomes, among which 23 pairs showed the same mapping regions, respectively. Meanwhile, among these pleiotropism epistatic QTLs, six of them played functions through the ‘single-to-multiple’ QTLs interaction modes, and 16 of them through the ‘single-to-single’ QTLs interaction modes. Thus, these epistatic QTLs not only provided the important selection markers for the molecular genetic improvements of soybean pod and seed traits, but also laid the important foundations for the molecular genetic mechanisms studies of soybean pod and seed related genes in future.