The phosphoproteomic and interactomic landscape of qGL3/OsPPKL1‐mediated brassinosteroid signaling in rice
Xiuying Gao, Jiaqi Zhang, Jianbo Li, Yuji Wang, Rong Zhang, Huaying Du, Jing Yin, Guang Zuan Cai, Ruqin Wang, Baoyi Zhang, Zhuang Zhao, Hongsheng Zhang, Ji Huang
Abstract
SUMMARY Oryza sativa L. (rice) is one of the most important crops in the world, and grain size is a major component determining rice yield. Recent studies have identified a number of grain size regulators, which are involved in phytohormone signaling, G protein signaling, the mitogen‐activated protein kinase signaling pathway, the ubiquitin–proteasome pathway or transcriptional regulation. In a previous study, we cloned qGL3 / OsPPKL1 encoding a rice protein phosphatase that negatively modulates brassinosteroid (BR) signaling and grain length. Here, to further explore the qGL3‐mediated BR signaling network, we performed phosphoproteomic screenings using two pairs of rice materials: the indica rice cultivar 9311 and its near‐isogenic line NIL qgl3 and the japonica rice cultivar Dongjin and its qGL3 knockout mutant m‐qgl3 . Together with qGL3‐interacting proteins, we constructed the qGL3‐mediated network, which reveals the relationships between BR signaling and other critical signaling pathways. Transgenic plants of these network components showed BR‐related alterations in plant architecture. From this network, we validated a qGL3‐interacting protein, O. sativa VERNALIZATION INSENSITIVE 3‐LIKE 1 (OsVIL1), and demonstrated that qGL3 dephosphorylates OsVIL1 to modulate BR signaling. The qGL3‐dependent network uncovered in this study increases our understanding of BR signaling and provides a profound foundation for addressing how BR modulates plant architecture in rice.