Chitin perception in plasmodesmata characterizes submembrane immune-signaling specificity in plants

Significance Plasmodesmata connect the cytoplasm of neighboring plant cells across cell walls. In response to various signals, they open and close to connect and isolate cells. We have found that the plasmodesmal plasma membrane hosts a unique immune-signaling cascade—different from that in the surrounding plasma membrane—which leads to plasmodesmata closure and cell isolation upon chitin perception. This response is mediated by a specific receptor complex, which in turn activates an NADPH oxidase via a specific regulatory module. This work characterizes how a cell can produce a localized and specific response in a discrete membrane domain, identifying that there is microdomain specificity in immune signaling to a single elicitor and that cell-to-cell connections are independently controlled.