提出问题：Rapid influx of calcium ions (Ca2+) across the plasma membrane plays an important role in this response, but the identity of Ca2+ channelsinvolved has remained elusive.

主要发现：Here, we report that the Arabidopsis thaliana Ca2+-permeable channel OSCA1.3 controls stomatal closure during immunity.

结果1-OSCA1.3蛋白快速响应PAMP被磷酸化：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.

结果2-OSCA1.3蛋白允许钙离子通过：Genetic and electrophysiological data reveal that OSCA1.3 is permeable to Ca2+, and that BIK1-mediated phosphorylation on its N-terminus increases this channel activity. Importantly, OSCA1.3 and its phosphorylation by BIK1 are critical for stomatal closure during immunity.

结果2-OSCA1.3蛋白不响应非生物胁迫：Notably, OSCA1.3 does not regulate stomatal closure upon perception of abscisic acid – a plant hormone associated with abiotic stresses.

结论：Our study thus identifies a long sought-after plant Ca2+ channel and its activation mechanisms underlying stomatal closure during immune signaling, and suggests specificity in Ca2+ influx mechanisms in response to different stresses.