Redox-calcium crosstalk in plants: proposed regulatory roles for nitric oxide and hydrogen sulfide in CBL-CIPK-mediated stress responses.

Calcium (Ca2+) signaling governs plant responses to abiotic stress; however, its integration with redox regulation remains unclear. In this review, we propose that thiol-based oxidative post-translational modifications may fine-tune the activity of CBL-CIPK (calcineurin B-like protein-CBL-interacting protein kinase) Ca2+ decoder complexes. Emerging insights on nitric oxide (NO), hydrogen sulfide (H2S), and reactive oxygen species are integrated with computational mapping of predicted redox-sensitive cysteines within CIPKs. The resulting model suggests a redox-tunable decoding mechanism linking Ca2+ fluxes with oxidative cues. To validate this framework, we highlight approaches including redox proteomics, site-directed mutagenesis, and live-cell Ca2+ imaging, while noting that direct regulation of CBL-CIPK complexes by NO and H2S remains hypothetical but testable.