Calcium-dependent protein kinases CPK3/4/6/11 and 27 respond to osmotic stress and activate SnRK2s in Arabidopsis

Qingzhong Li; Tao Hu; Tianjiao Lu; Bo Yu; Yang Zhao

doi:10.1016/j.devcel.2024.12.036

Calcium-dependent protein kinases CPK3/4/6/11 and 27 respond to osmotic stress and activate SnRK2s in Arabidopsis

Dev Cell. 2025 Jan 6:S1534-5807(24)00774-3. doi: 10.1016/j.devcel.2024.12.036. Online ahead of print.

Authors

Qingzhong Li¹, Tao Hu¹, Tianjiao Lu², Bo Yu¹, Yang Zhao³

Affiliations

¹ Key Laboratory of Plant Carbon Capture, Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
² Key Laboratory of Plant Carbon Capture, Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China; University of Chinese Academy of Sciences, Beijing 100049, China.
³ Key Laboratory of Plant Carbon Capture, Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: yangzhao@psc.ac.cn.

PMID: 39814016
DOI: 10.1016/j.devcel.2024.12.036

Abstract

Drought and salinity are significant environmental threats that cause hyperosmotic stress in plants, which respond with a transient elevation of cytosolic Ca²⁺ and activation of Snf1-related protein kinase 2s (SnRK2s) and downstream responses. The exact regulators decoding Ca²⁺ signals to activate downstream responses remained unclear. Here, we show that the calcium-dependent protein kinases CPK3/4/6/11 and 27 respond to moderate osmotic stress and dehydration to activate SnRK2 phosphorylation in Arabidopsis. Using quantitative phosphoproteomics in a higher-order mutant lacking 12 pyrabactin resistance 1-like (PYL) abscisic acid (ABA) receptors, we identified six CPKs that are phosphorylated under osmotic stress. CPK3/4/6/11/27 phosphorylate the SnRK2s on multiple phosphosites within the activation loop. The cpk3/4/6/11/27 mutant is defective in SnRK2 activation, seed germination, and seedling growth under mild osmotic stress. Our findings elucidate the critical roles of CPK3/4/6/11/27 in decoding Ca²⁺ signals to activate SnRK2s and demonstrate a CPK-SnRK2 kinase cascade controlling osmotic stress responses in plants.

Keywords: ABA receptors; ABA-independent; CPK3/4/6/11/27; PYR/PYL; SnRK2; Snf1-related protein kinase 2; calcium-dependent protein kinase; osmotic stress; pyrabactin resistance.