Hydrogen peroxide signalling

Recent biochemical and genetic studies confirm that hydrogen peroxide is a signalling molecule in plants that mediates responses to abiotic and biotic stresses. Signalling roles for hydrogen peroxide during abscisic-acid-mediated stomatal closure, auxin-regulated root gravitropism and tolerance of oxygen deprivation are now evident. The synthesis and action of hydrogen peroxide appear to be linked to those of nitric oxide. Downstream signalling events that are modulated by hydrogen peroxide include calcium mobilisation, protein phosphorylation and gene expression. Calcium and Rop signalling contribute to the maintenance of hydrogen peroxide homeostasis.