Physiological roles of nonselective cation channels in plants: from salt stress to signalling and development

Summary Nonselective cation channels (NSCCs) catalyse passive fluxes of cations through plant membranes. NSCCs do not, or only to a small extent, select between monovalent cations, and several are also permeable to divalent cations. Although a number of NSCC genes has been identified in plant genomes, a direct correlation between gene products and in vivo observed currents is still largely absent for most NSCCs. In this review, physiological functions and molecular properties of NSCCs are critically discussed. Recent studies have demonstrated that NSCCs are directly involved in a multitude of stress responses, growth and development, uptake of nutrients and calcium signalling. NSCCs can also function in the perception of external stimuli and as signal transducers for reactive oxygen species, pathogen elicitors, cyclic nucleotides, membrane stretch, amino acids and purines. Contents Summary 387 I. Introduction 388 II. Constitutive plasma membrane NSCCs 389 III. NSCCs activated by reactive oxygen species (ROS‐NSCCs) 392 IV. Cyclic nucleotide‐gated channels (CNGCs) 393 V. Amino acid‐gated NSCCs 395 VI. Purine signalling 396 VII. Mechanosensitive ion channels 396 VIII. Vacuolar NSCCs 396 IX. Cation channels sensitive to elicitors 397 X. NSCCs acting in concert 398 XI. Conclusions and perspectives 398 References 400