WeiTsing: a new face of Ca-permeable channels in plant immunity.

Plants employ pattern- and effector-triggered immunity (PTI and ETI) to synergistically defend invading pathogens and insect herbivores. Both PTI and ETI can induce cytosolic Ca spikes, despite in different spatiotemporal patterns, to activate downstream Ca-dependent immune signaling cascades. While multiple families of Ca-permeable channels at the plasma membrane have been uncovered, the counterparts responsible for Ca release from intracellular stores remain poorly understood. In a groundbreaking paper published recently by Cell, the authors reported that WeiTsing, an Arabidopsis endoplasmic reticulum (ER)-resident protein that was specifically expressed in the pericycle upon Plasmodiophora brassicae (Pb) infection, could form resistosome-like Ca-conducting channel and protect the stele of Brassica crops from Pb colonization. As the channel activity of WeiTsing was indispensable for its immune function, the findings highlight a previously underappreciated role of Ca release from intracellular repertoire in promoting plant disease resistance.