The Function of Cyclic Nucleotide-Gated Channels in Biotic Stress

Abstract

Plant cyclic nucleotide-gated ion channels conduct Ca 2+ across the plasma membrane (PM) and facilitate cytosolic Ca 2+ elevation during pathogen response signaling cascades. Until recently, not much was known about the specific ion channels involved in Ca 2+ influx into plant cells, or how Ca 2+ signals are generated and impact on downstream events during pathogen resistance responses. Recent studies, involving the cyclic nucleotide gated ion channel (CNGC) family of proteins, have provided new information relevant to these two areas of plant biology and will be reviewed in this chapter. Current evidence points to specific proteins that synthesize cyclic nucleotides and that function as ligands to activate CNGCs. The role of these channels in Ca 2+ conduction appears critical to the generation of the hypersensitive response to pathogens, an important defense mechanism that limits disease in plants. Signaling downstream from Ca 2+ during biotic stress responses involves cytosolic Ca 2+ -binding proteins such as calmodulin.