Cyclic Nucleotide Gated Channels and Ca2+-Mediated Signal Transduction During Plant Innate Immune Response to Pathogens

Abstract

Transitory perturbations in the level of cytosolic Ca2+ are well known to be involved in numerous cell signaling pathways in both plant and animal systems. However, not much is known at present about the molecular identity of plant plasma membrane Ca2+ conducting ion channels or their specific roles in signal transduction cascades. A recent study employing genetic approaches as well as patch clamp electrophysiological analysis of channel currents has provided the first such direct evidence linking a specific gene product with inward Ca2+ currents across the plant cell membrane. This work identified Ca2+ permeation through (Arabidopsis) cyclic nucleotide gated channel isoform 2 (CNGC2) as contributing to the plant innate immunity signaling cascade initiated upon perception of a pathogen. Here, we expand on the implications of CNGC2 mediated cytosolic Ca2+ elevations associated with plant cell response to pathogen recognition, and propose some additional steps that may be involved in the innate immunity signal cascade.