2025/01/07 by Ivan Kulich, Denisa Oulehlová, Dmitrii Vladimirtsev +17 · 2 voices
Agricultural and Biological Sciences · Biochemistry, Genetics and Molecular Biology · #Photosynthetic Processes and Mechanisms #Plant Molecular Biology Research #Plant Stress Responses and Tolerance
paper · pdf · doi:10.1101/2025.01.06.631460
openalex publication_date 2025/01/07 · openalex created_date 2025/01/08 · openalex updated_date 2026/07/28
Abstract The versatile Ca 2+ signaling system governs plant responses to a wide array of environmental and developmental cues. CYCLIC NUCLEOTIDE-GATED CHANNELS (CNGCs) trigger cellular responses to diverse signals, including phytohormones, biotic and abiotic stresses; and as such their activity is tightly controlled. Unlike their animal paralogs, plant CNGCs does not seem to be gated by cyclic nucleotides, and the mechanism of their activation remains unresolved. Here we report ARMADILLO REPEAT ONLY (ARO) proteins as novel, plant-specific, and essential activators of plant CNGCs. Reciprocal proximity labeling revealed interactions between all sporophytic CNGCs and AROs. Loss-of-function aro mutants fail to induce Ca 2+ transients in response to known CNGC-triggering stimuli. Structural modeling, mutational analysis, and electrophysiological data show that AROs assemble into a complex with CNGC tetramers by interaction with the conserved Calmodulin-binding IQ domain. AROs represent CNGC activators, competing with Calmodulins, showcasing an evolutionarily unique solution to regulation of calcium signaling in plants.