Gao Xiuying, Zhang Jiaqi, Li Jianbo, Wang Yuji, Zhang Rong, Du Huaying, Yin Jing, Cai Guang, Wang Ruqin, Zhang Baoyi, Zhao Zhuang, Zhang Hongsheng, Huang Ji
State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China.
Jiangsu Provincial Engineering Research Center of Seed Industry Science and Technology, Nanjing, 210095, China.
Plant J. 2022 Mar;109(5):1048-1063. doi: 10.1111/tpj.15613. Epub 2021 Dec 15.
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 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.
水稻（Oryza sativa L.）是世界上最重要的作物之一，谷粒大小是决定水稻产量的主要因素。最近的研究已经鉴定出许多谷粒大小调节因子，它们参与植物激素信号传导、G蛋白信号传导、丝裂原活化蛋白激酶信号通路、泛素-蛋白酶体通路或转录调控。在之前的一项研究中，我们克隆了编码水稻蛋白磷酸酶的qGL3/OsPPKL1，该蛋白磷酸酶负向调节油菜素内酯（BR）信号传导和谷粒长度。在此，为了进一步探索qGL3介导的BR信号网络，我们使用两对水稻材料进行了磷酸化蛋白质组学筛选：籼稻品种9311及其近等基因系NIL，以及粳稻品种东津及其qGL3基因敲除突变体m-qgl3。结合与qGL3相互作用的蛋白质，我们构建了qGL3介导的网络，揭示了BR信号传导与其他关键信号通路之间的关系。这些网络组件的转基因植物在植株形态上表现出与BR相关的变化。从这个网络中，我们验证了一个与qGL3相互作用的蛋白质，水稻春化不敏感3样蛋白1（OsVIL1），并证明qGL3使OsVIL1去磷酸化以调节BR信号传导。本研究中发现的qGL3依赖性网络加深了我们对BR信号传导的理解，并为解决BR如何调节水稻植株形态提供了深厚的基础。
