籽粒大小是大豆育种所关注的重要性状之一，与大豆的产量和品质密切相关。然而，因种子发育由复杂的数量性状位点所控制，大豆籽粒大小的关键调控基因及其具体分子机制仍不十分清楚。我们前期分别利用TK780xH4及SN14xEnrei两个F8重组自交群体对控制籽粒大小的位点进行QTL定位，发现19号染色体上存在一个重要位点可能参与到籽粒的发育调控当中。进一步精细定位发现未知功能基因SW1可能编码这一关键QTL位点，调控大豆籽粒的大小和粒重。对SW1/sw1近等基因系的分析显示两个株系在籽粒大小、百粒重、营养物质含量及萌发率上都有显著差异，表明SW1的确作为重要基因参与到大豆籽粒的发育过程中。在此基础上，本项目拟从生理、分子及遗传水平上对SW1基因在大豆种子发育中的角色和功能进行深入探究，阐明大豆籽粒大小发育的具体调控机制，以促进植物种子发育调控的理论认知，并为提高大豆高产优质分子育种效率提供理论依据。

Seed size is one of major traits concerned in soybean breeding, which is tightly correlated with soybean yield and quality. However, as seed development is controlled by a series of complicated quantitative loci, the key genes and detailed mechanism involved in so far remain obscure. We previously analyzed the QTLs controlling seed size using two inbred F8 populations from soybean TK780xH4 and SN14xEnrei, respectively, and found a major locus in 19th chromosome probably involved in seed development regulation. Further fine-mapping revealed that an unknown function gene SW1 may encode this key QTL locus to regulate seed size and weight in soybean. Analysis on SW1/sw1 NILs demonstrated that there are significant differences in seeds size, hundred seeds weight, nutrient content, and germination rate between these two lines, indicating SW1 indeed contributes to soybean seed development. Here, we will investigate SW1 gene role and function in soybean seed development by means of analyses of physiology, molecular, and genetics, and reveal the detailed mechanism of soybean seed size control. These findings will shed lights on how plants regulate seed development and provide technologic basis for raising breeding efficiency of soybean varieties with high yield and quality.