Kamiyama Yoshiaki, Katagiri Sotaro, Li Yangdan, Yamashita Kota, Takase Hinano, Umezawa Taishi
Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei 184-8588, Tokyo, Japan.
Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu 183-8538, Tokyo, Japan.
Proc Natl Acad Sci U S A. 2024 Dec 24;121(52):e2419204121. doi: 10.1073/pnas.2419204121. Epub 2024 Dec 19.
When plants are exposed to drought stress, there is a trade-off between plant growth and stress responses. Here, we identified a signaling mechanism for the initial steps of the drought-growth trade-off. Phosphoproteomic profiling revealed that Raf13, a B1 subgroup Raf-like kinase, is dephosphorylated under drought conditions. Raf13 and the related B1-Raf Raf15 are required for growth rather than the acquisition of osmotolerance. We also found that Raf13 interacts with B55-family regulatory subunits of protein phosphatase 2A (PP2A), which mediates hyperosmolarity-induced dephosphorylation of Raf13. In addition, Raf13 interacts with an AGC kinase INCOMPLETE ROOT HAIR ELONGATION HOMOLOG 1 (IREH1), and Raf13 and IREH1 have similar functions in regulating cellular responses that promote plant growth. Overall, our results support a model in which Raf13-IREH1 activity promotes growth under nonstressed conditions, whereas PP2A activity suppresses Raf13-IREH1 during osmotic stress to modulate the physiological "trade-off" between plant growth and stress responses.
当植物受到干旱胁迫时，植物生长与胁迫反应之间存在权衡。在此，我们确定了干旱-生长权衡初始步骤的信号传导机制。磷酸化蛋白质组分析表明，一种B1亚组类Raf激酶Raf13在干旱条件下发生去磷酸化。Raf13和相关的B1-Raf Raf15是生长所必需的，而非渗透耐受性获得所必需。我们还发现，Raf13与蛋白磷酸酶2A（PP2A）的B55家族调节亚基相互作用，PP2A介导高渗诱导的Raf13去磷酸化。此外，Raf13与一种AGC激酶不完全根毛伸长同源物1（IREH1）相互作用，并且Raf13和IREH1在调节促进植物生长的细胞反应中具有相似功能。总体而言，我们的结果支持一种模型，即Raf13-IREH1活性在非胁迫条件下促进生长，而在渗透胁迫期间PP2A活性抑制Raf13-IREH1，以调节植物生长与胁迫反应之间的生理“权衡”。
