Cui Minghan, Li Yanping, Li Jianhang, Yin Fengxiang, Chen Xiangyu, Qin Lumin, Wei Lin, Xia Guangmin, Liu Shuwei
Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Science, Shandong University, Qingdao 266237, China.
Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Science, Shandong University, Qingdao 266237, China.
Mol Plant. 2023 Mar 6;16(3):571-587. doi: 10.1016/j.molp.2023.01.010. Epub 2023 Jan 21.
Alkali stress is a major constraint for crop production in many regions of saline-alkali land. However, little is known about the mechanisms through which wheat responds to alkali stress. In this study, we identified a calcium ion-binding protein from wheat, TaCCD1, which is critical for regulating the plasma membrane (PM) H-ATPase-mediated alkali stress response. PM H-ATPase activity is closely related to alkali tolerance in the wheat variety Shanrong 4 (SR4). We found that two D-clade type 2C protein phosphatases, TaPP2C.D1 and TaPP2C.D8 (TaPP2C.D1/8), negatively modulate alkali stress tolerance by dephosphorylating the penultimate threonine residue (Thr926) of TaHA2 and thereby inhibiting PM H-ATPase activity. Alkali stress induces the expression of TaCCD1 in SR4, and TaCCD1 interacts with TaSAUR215, an early auxin-responsive protein. These responses are both dependent on calcium signaling triggered by alkali stress. TaCCD1 enhances the inhibitory effect of TaSAUR215 on TaPP2C.D1/8 activity, thereby promoting the activity of the PM H-ATPase TaHA2 and alkali stress tolerance in wheat. Functional and genetic analyses verified the effects of these genes in response to alkali stress, indicating that TaPP2C.D1/8 function downstream of TaSAUR215 and TaCCD1. Collectively, this study uncovers a new signaling pathway that regulates wheat responses to alkali stress, in which Ca-dependent TaCCD1 cooperates with TaSAUR215 to enhance PM H-ATPase activity and alkali stress tolerance by inhibiting TaPP2C.D1/8-mediated dephosphorylation of PM H-ATPase TaHA2 in wheat.
碱胁迫是盐碱地许多地区作物生产的主要限制因素。然而，关于小麦对碱胁迫的响应机制知之甚少。在本研究中，我们从小麦中鉴定出一种钙离子结合蛋白TaCCD1，它对调节质膜（PM）H-ATPase介导的碱胁迫响应至关重要。PM H-ATPase活性与小麦品种山融4号（SR4）的耐碱性密切相关。我们发现两种D类2C型蛋白磷酸酶TaPP2C.D1和TaPP2C.D8（TaPP2C.D1/8）通过使TaHA2的倒数第二个苏氨酸残基（Thr926）去磷酸化，从而抑制PM H-ATPase活性，对碱胁迫耐受性产生负调控作用。碱胁迫诱导SR4中TaCCD1的表达，并且TaCCD1与早期生长素响应蛋白TaSAUR215相互作用。这些响应都依赖于碱胁迫触发的钙信号传导。TaCCD1增强TaSAUR215对TaPP2C.D1/8活性的抑制作用，从而促进质膜H-ATPase TaHA2的活性和小麦的碱胁迫耐受性。功能和遗传分析验证了这些基因对碱胁迫响应的作用，表明TaPP2C.D1/8在TaSAUR215和TaCCD1的下游发挥作用。总的来说，本研究揭示了一条调节小麦对碱胁迫响应的新信号通路，其中钙依赖的TaCCD1与TaSAUR215协同作用，通过抑制TaPP-C.D1/8介导的小麦质膜H-ATPase TaHA2的去磷酸化作用，增强质膜H-ATPase活性和碱胁迫耐受性。
