Calcium in plant defence‐signalling pathways

Summary In plant cells, the calcium ion is a ubiquitous intracellular second messenger involved in numerous signalling pathways. Variations in the cytosolic concentration of Ca 2+ ([Ca 2+ ] cyt ) couple a large array of signals and responses. Here we concentrate on calcium signalling in plant defence responses, particularly on the generation of the calcium signal and downstream calcium‐dependent events participating in the establishment of defence responses with special reference to calcium‐binding proteins. Contents I. Introduction 250 II. Increases in free cellular [Ca 2+ ]: an early and key event in plant defence signalling 251 III. Relationships between [Ca 2+ ] cyt increases and defence‐signalling…