BACKGROUND The 100-pod fresh weight (PFW), 100-seed fresh weight (SFW), 100-seed dry weight (SDW) and moisture content of fresh seeds (MCFS) at the R6 stage are crucial factors for vegetable soybean yield. However, the genetic basis of yield at the R6 stage remains largely ambiguous in soybean. RESULTS To better understand the molecular mechanism underlying yield, we investigated four yield-related traits of 133 soybean landraces in two consecutive years and conducted a genome-wide association study (GWAS) using 82,187 single nucleotide polymorphisms (SNPs). The GWAS results revealed a total of 14, 15, 63 and 48 SNPs for PFW, SFW, SDW and MCFS, respectively. Among these markers, 35 SNPs were repeatedly identified in all evaluated environments (2015, 2016, and the average across the two years), and most co-localized with yield-related QTLs identified in previous studies. AX-90496773 and AX-90460290 were large-effect markers for PFW and MCFS, respectively. The two markers were stably identified in all environments and tagged to linkage disequilibrium (LD) blocks. Six potential candidate genes were predicted in LD blocks; five of them showed significantly different expression levels between the extreme materials with large PFW or MCFS variation at the seed development stage. Therefore, the five genes Glyma.16g018200, Glyma.16g018300, Glyma.05g243400, Glyma.05g244100 and Glyma.05g245300 were regarded as candidate genes associated with PFW and MCFS. CONCLUSION These results provide useful information for the development of functional markers and exploration of candidate genes in vegetable soybean high-yield breeding programs.

中文翻译：

---

大豆R6阶段四个与产量相关的性状的全基因组关联研究。

背景技术在R6阶段，100荚新鲜重量（PFW），100种子新鲜重量（SFW），100种子干重量（SDW）和新鲜种子的水分含量（MCFS）是蔬菜大豆产量的关键因素。然而，大豆在R6阶段的产量遗传基础仍然不明确。结果为了更好地了解产量的分子机制，我们连续两年调查了133个大豆地方品种的四个产量相关性状，并使用82,187个单核苷酸多态性（SNP）进行了全基因组关联研究（GWAS）。GWAS结果显示，PFW，SFW，SDW和MCFS分别有14、15、63和48个SNP。在这些标记中，在所有评估的环境中（2015年，2016年以及两年的平均值）重复鉴定了35个SNP，并且大多数与先前研究中确定的与产量相关的QTL共同定位。AX-90496773和AX-90460290分别是PFW和MCFS的大效果标记。在所有环境中都稳定地鉴定了这两个标记，并标记了连锁不平衡（LD）区块。在LD区中预测了六个潜在的候选基因；其中五种在种子发育阶段的PFW或MCFS变化较大的极端材料之间显示出明显不同的表达水平。因此，将五个基因Glyma.16g018200，Glyma.16g018300，​​Glyma.05g243400，Glyma.05g244100和Glyma.05g245300视为与PFW和MCFS相关的候选基因。结论这些结果为蔬菜大豆高产育种计划中功能标记的开发和候选基因的探索提供了有用的信息。