Control of grain size in rice by TGW3 phosphorylation of OsIAA10 through potentiation of OsIAA10-OsARF4-mediated auxin signaling
Ming Ma,
Shao-Yan Shen,
Chen Bai,
Wei-Qing Wang,
Xiao-Hui Feng,
Jie-Zheng Ying,
Xian-Jun Song
Affiliations
Ming Ma
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
Shao-Yan Shen
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
Chen Bai
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
Wei-Qing Wang
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
Xiao-Hui Feng
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
Jie-Zheng Ying
National Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China
Xian-Jun Song
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China; Corresponding author
Summary: Grain size is a key component of grain yield and quality in crops. Several core players of auxin signaling have been revealed to modulate grain size; however, to date, few genetically defined pathways have been reported, and whether phosphorylation could boost degradation of Aux/IAA proteins is uncertain. Here, we show that TGW3 (also called OsGSK5) interacts with and phosphorylates OsIAA10. Phosphorylation of OsIAA10 facilitates its interaction with OsTIR1 and subsequent destabilization, but this modification hinders its interaction with OsARF4. Our genetic and molecular evidence identifies an OsTIR1-OsIAA10-OsARF4 axis as key for grain size control. In addition, physiological and molecular studies suggest that TGW3 mediates the brassinosteroid response, the effect of which can be relayed through the regulatory axis. Collectively, these findings define a auxin signaling pathway to regulate grain size, in which phosphorylation of OsIAA10 enhances its proteolysis and potentiates OsIAA10-OsARF4-mediated auxin signaling.
