Thor K, Jiang S, Michard E, George J, Scherzer S, Huang S, Dindas J, Derbyshire P, Leitão N, DeFalco TA, Köster P, Hunter K, Kimura S, Gronnier J, Stransfeld L, Kadota Y, Bücherl CA, Charpentier M, Wrzaczek M, MacLean D, Oldroyd GED, Menke FLH, Roelfsema MRG, Hedrich R, Feijó J, Zipfel C. The calcium-permeable channel OSCA1.3 regulates plant stomatal immunity. Nature. 2020 Aug 26. doi: 10.1038/s41586-020-2702-1. Epub ahead of print. PMID: 32846426.
Perception of biotic and abiotic stresses often leads to stomatal closure in plants. Rapid influx of calcium ions (Ca2+) across the plasma membrane plays an important role in this response, but the identity of Ca2+ channels involved has remained elusive.
Here, we report that the Arabidopsis thaliana Ca2+-permeable channel OSCA1.3 controls stomatal closure during immunity. OSCA1.3 is rapidly phosphorylated upon perception of pathogen-associated molecular patterns (PAMPs). Biochemical and quantitative phospho-proteomics analyses reveal that the immune receptor associated cytosolic kinase BIK1 interacts with and phosphorylates the N-terminal cytosolic loop of OSCA1.3 within minutes of treatment with the peptidic PAMP flg22 derived from bacterial flagellin.
Arabidopsis Col-0 wildtype and bik1 pbl1 mutant seedlings were treated with flg22 for 0 and 5 min and flash frozen. Phosphopeptide were extracted and enriched as described in Mithoe et al.,(2016). Phosphopeptide level were quantified by SRM after assays were set up using synthetic phosphopeptide.