New insight into Ca 2+ -permeable channel in plant immunity

Calcium ions (Ca ) are crucial intracellular second messengers in eukaryotic cells. Upon pathogen perception, plants generate a transient and rapid increase in cytoplasmic Ca levels, which is subsequently decoded by Ca sensors and effectors to activate downstream immune responses. The elevation of cytosolic Ca is commonly attributed to Ca influx mediated by plasma membrane-localized Ca -permeable channels. However, the contribution of Ca release triggered by intracellular Ca -permeable channels in shaping Ca signaling associated with plant immunity remains poorly understood. This review discusses recent advances in understanding the mechanism underlying the shaping of Ca signatures upon the activation of immune receptors, with particular emphasis on the identification of intracellular immune receptors as non-canonical Ca -permeable channels. We also discuss the involvement of Ca release from the endoplasmic reticulum in generating Ca signaling during plant immunity.