Hydrogen sulphide regulates inward-rectifying K+ channels in conjunction with stomatal closure

Hydrogen sulphide (H2S) is the third biological gasotransmitter and, in animals, affects many physiological processes by modulating ion channels. H2S has been reported to protect plants from oxidative stress in diverse physiological responses. H2S closes stomata, but the underlying mechanism remains elusive. Here we report the selective inactivation of current carried by inward-rectifying K+ channels (IKIN) of tobacco guard cells and demonstrate its close parallel with stomatal closure evoked by submicromolar concentrations of H2S. Experiments to scavenge H2S suggested an effect that is separable from that of abscisic acid, which is associated with water stress. Thus, H2S appears to associate with a new and as yet unresolved signalling pathway that selectively targets IKIN