The GW2-WG1-OsbZIP47 pathway controls grain size and weight in rice

摘要

Regulation of seed size is a key strategy for improving crop yield and is also a basic biological question.However,the molecular mechanisms by which plants determine their seed size remain elusive.Here,we report that the GW2-WG1-OsbZIP47 regulatory module controls grain width and weight in rice.WG1,which encodes a glutaredoxin protein,promotes grain growth by increasing cell proliferation.Interestingly,WG1 interacts with the transcription factor OsbZIP47 and represses its transcriptional activity by associating with the transcriptional co-repressor ASP1,indicating that WG1 may act as an adaptor protein to recruit the transcriptional co-repressor.In contrary,OsbZIP47 restricts grain growth by decreasing cell prolifera-tion.Further studies reveal that the E3 ubiquitin ligase GW2 ubiquitinates WG1 and targets it for degrada-tion.Genetic analyses confirm that GW2,WG1,and OsbZIP47 function in a common pathway to control grain growth.Taken together,our findings reveal a genetic and molecular framework for the control of grain size and weight by the GW2-WG1-OsbZIP47 regulatory module,providing new targets for improving seed size and weight in crops.