Miao Rui, Yuan Wei, Wang Yue, Garcia-Maquilon Irene, Dang Xiaolin, Li Ying, Zhang Jianhua, Zhu Yiyong, Rodriguez Pedro L, Xu Weifeng
Center for Plant Water-Use and Nutrition Regulation and College of Life Sciences, Joint International Research Laboratory of Water and Nutrient in Crops, Fujian Agriculture and Forestry University, Jinshan Fuzhou 350002, China.
Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Cientificas-Universidad Politecnica de Valencia, ES-46022 Valencia, Spain.
Sci Adv. 2021 Mar 17;7(12). doi: 10.1126/sciadv.abd4113. Print 2021 Mar.
The quadruple mutant () seedlings lacking key negative regulators of ABA signaling, namely, clade A protein phosphatases type 2C (PP2Cs), show more apoplastic H efflux in roots and display an enhanced root growth under normal medium or water stress medium compared to the wild type. The presence of low ABA concentration (0.1 micromolar), inhibiting PP2C activity via monomeric ABA receptors, enhances root apoplastic H efflux and growth of the wild type, resembling the phenotype in normal medium. seedlings also demonstrate increased hydrotropism compared to the wild type in obliquely-oriented hydrotropic experimental system, and asymmetric H efflux in root elongation zone is crucial for root hydrotropism. Moreover, we reveal that ABA-insensitive 1, a key PP2C in ABA signaling, interacts directly with the C terminus of plasma membrane H-dependent adenosine triphosphatase 2 (AHA2) and dephosphorylates its penultimate threonine residue (Thr), whose dephosphorylation negatively regulates AHA2.
缺乏ABA信号关键负调控因子（即A类2C型蛋白磷酸酶（PP2C））的四重突变体幼苗，与野生型相比，根部表现出更多的质外体H⁺外流，并且在正常培养基或水分胁迫培养基下根系生长增强。低浓度ABA（0.1微摩尔）通过单体ABA受体抑制PP2C活性，增强了野生型的根质外体H⁺外流和生长，类似于正常培养基中的四重突变体表型。在倾斜定向的向水性实验系统中，四重突变体幼苗与野生型相比也表现出增强的向水性，并且根伸长区的不对称H⁺外流对于根的向水性至关重要。此外，我们发现ABA信号中的关键PP2C——ABA不敏感1，直接与质膜H⁺依赖的腺苷三磷酸酶2（AHA2）的C末端相互作用，并使其倒数第二个苏氨酸残基（Thr）去磷酸化，该残基的去磷酸化对AHA2起负调控作用。
