Soybean grain yield at the population level lags behind staple crops like rice, wheat, and maize, which benefit from semi-dwarf phenotypes enabling high-density planting. This study characterized a short-internode soybean mutant, *reduced internode 1* (*rin1*), which is caused by a partial loss-of-function of *SPA3a*. RIN1 interacts with STF1 and STF2, promoting their degradation and regulating gibberellin metabolism via a STF1/STF2-GA20ox7 module, controlling internode development. Field trials showed *rin1* significantly improves grain yield under high-density planting compared to the wild type. Therefore, *rin1* is a valuable resource for improving soybean yield in high-density cultivation and intercropping systems.

Shichen Li, Zhihui Sun, Qing Sang, Chao Qin, Lingping Kong, Xin Huang, Huan Liu, Tong Su, Haiyang Li, Milan He, Chao Fang, Lingshuang Wang, Shuangrong Liu, Bin Liu, Baohui Liu, Xiangdong Fu, Fanjiang Kong, Sijia Lu