| 描述信息 |
Grain size is one of crucial agronomic traits that influence grain yield in crops, thus understanding the genetic and molecular mechanisms of grain size control is important for improving crop yield. The transcription factor GS2/OsGRF4 improves grain size and yield and becomes a potential target for new green revolution rice varieties. However, how GS2 determines grain size remains unclear. Here we report a suppressor of the gain of function allele GS2AA (SUG1), which encodes a transcriptional regulator. The sug1 mutants form short grains, while overexpression of SUG1 results in long grains. GS2 binds to the promoter region of SUG1 to activate its expression and regulates grain size. SUG1 associates with multiple transcription factors, such as OsBZR1, OsMADS56 and OsSPL13, to control grain size through GA and BR signaling as well as growth pathways. Further results reveal that natural variation in SUG1 contributes to grain size diversity, and the natural allele SUG1Hap2 from indica varieties can be used to improve grain size and yield of japonica varieties with the SUG1Hap3 allele. Thus, our findings uncover a previously unrecognized molecular framework by which GS2 activates the transcription of SUG1 that acts as a hub to integrate distinct transcription factors for controlling grain size through several phytohormone and growth pathways, suggesting that they are promising targets for grain size and yield improvement in crops. |
