王存等《The Plant Cell》2024年

论文题目：Arabidopsis CALCIUM-DEPENDENT PROTEIN KINASE4/5/6/11 negatively regulate hydrotropism via phosphorylation of MIZU-KUSSEI1

论文作者：Chuanfeng Ju, Laiba Javed, Yanjun Fang, Yuqing Zhao, Chenyu Cao, Yuan Deng, Yaqi Gao, Lv Sun, Cun Wang*

论文摘要：

Hydrotropism facilitates the orientation of plant roots towards regions of elevated water potential, enabling them to absorb adequate water. Although calcium signaling plays a crucial role in plant response to water tracking, the exact regulatory mechanisms remain a mystery. Here, we employed the Arabidopsis (Arabidopsis thaliana) hydrotropism-specific protein MIZU-KUSSEI1 (MIZ1) as bait and found that calcium-dependent protein kinases4/5/6/11 (CPK4/5/6/11) interacted with MIZ1 in vitro and in vivo. The cpk4/5/6/11 mutant exhibited increased sensitivity to water potential and enhanced root tip curvature. Furthermore, CPK4/5/6/11 primarily phosphorylated MIZ1 at Ser14/36 residues. Additionally, CPK-mediated phosphorylation of MIZ1 relieved its inhibitory effect on the activity of the endoplasmic reticulum–localized Ca2+ pump ECA1, altering the balance between cytoplasmic Ca2+ inflow and outflow, thereby negatively regulating the hydrotropic growth of plants. Overall, our findings unveil the molecular mechanisms by which the CPK4/5/6/11-MIZ1 module functions in regulating plant hydrotropism responses and provide a theoretical foundation for enhancing plant water use efficiency and promoting sustainable agriculture.

向水性有助于植物根系向水势较高的区域定向生长，从而使它们能够吸收足够的水分。尽管钙信号在植物向水性响应中起着至关重要的作用，但其确切的调控机制还很不清楚。本研究利用拟南芥向水性特异蛋白MIZ1作为诱饵，发现钙依赖蛋白激酶CPK4/5/6/11在体外和体内均与MIZ1相互作用。cpk4/5/6/11突变体对水势差的敏感性增加，根尖弯曲度增大。此外，CPK4/5/6/11主要磷酸化修饰MIZ1的Ser14/36残基。并且CPK介导的MIZ1磷酸化解除了其对内质网定位的Ca2+泵ECA1活性的抑制作用，从而改变了细胞质中Ca2+流入和流出的平衡，进而负向调控植物的向水性生长。该研究结果揭示了CPK4/5/6/11-MIZ1模块在调控植物向水性反应中的分子机制，为提高植物水分利用效率、促进农业可持续发展提供了理论依据。

论文链接：https://doi.org/10.1093/plcell/koae279