Ju Chuanfeng, Javed Laiba, Fang Yanjun, Zhao Yuqing, Cao Chenyu, Deng Yuan, Gao Yaqi, Sun Lv, Wang Cun
State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, College of Life Sciences, Northwest Agriculture and Forestry University, Yangling, Shaanxi 712100, China.
Institute of Future Agriculture, Northwest Agriculture and Forestry University, Yangling, Shaanxi 712100, China.
Plant Cell. 2024 Dec 23;37(1). doi: 10.1093/plcell/koae279.
Hydrotropism facilitates the orientation of plant roots toward 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 kinases 4/5/6/11 (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朝向水势较高的区域生长，使其能够吸收充足的水分。尽管钙信号在植物对水分追踪的响应中起着关键作用，但其确切的调控机制仍然是个谜。在此，我们以拟南芥向水性特异性蛋白水泽久世1（MIZ1）作为诱饵，发现钙依赖性蛋白激酶4/5/6/11（CPK4/5/6/11）在体外和体内均与MIZ1相互作用。cpk4/5/6/11突变体对水势表现出更高的敏感性，且根尖弯曲增强。此外，CPK4/5/6/11主要在丝氨酸14/36残基处磷酸化MIZ1。另外，CPK介导的MIZ1磷酸化解除了其对内质网定位钙泵ECA1活性的抑制作用，改变了细胞质钙流入与流出之间的平衡，从而对植物的向水生长产生负调控。总体而言，我们的研究结果揭示了CPK4/5/6/11-MIZ1模块在调节植物向水性反应中的分子机制，并为提高植物水分利用效率和促进可持续农业提供了理论基础。
