Ca(2+) signals in plant immunity

Calcium ions function as a key second messenger ion in eukaryotes. Spatially and temporally defined cytoplasmic Ca(2+) signals are shaped through the concerted activity of ion channels, exchangers, and pumps in response to diverse stimuli; these signals are then decoded through the activity of Ca(2+)‐binding sensor proteins. In plants, Ca(2+) signaling is central to both pattern‐ and effector‐triggered immunity, with the generation of characteristic cytoplasmic Ca(2+) elevations in response to potential pathogens being common to both. However, despite their importance, and a long history of scientific interest, the transport proteins that shape Ca(2+) signals and their integration remain poorly characterized. Here, we discuss recent work that has both shed light on and deepened the mysteries of Ca(2+) signaling in plant immunity.