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.