Deciphering hydrogen peroxide-induced signalling towards stress tolerance in plants

Plants encounter a variety of adverse environmental conditions, such as high salinity, drought, extreme heat/cold and heavy metals contamination (abiotic stress) or attack of various pathogens (biotic stress). These detrimental environmental factors enhanced the ROS production such as singlet oxygen (O-1(2)), superoxide (O2 center dot-), hydrogen peroxide (H2O2) and hydroxyl radicals (OH center dot). ROS are highly reactive and directly target several cellular molecules and metabolites, which lead to severe cellular dysfunction. Plants respond to oxidative damages by activating antioxidant machinery to trigger signalling cascades for stress tolerance. H2O2 signalling balances the plant metabolism through cross-talk with other signals and plant hormones during growth, development and stress responses. H2O2 facilitates the regulation of different stress-responsive transcription factors (TFs) including NAC, Zinc finger, WRKY, ERF, MYB, DREB and bZIP as both upstream and downstream events during stress signalling. The present review focuses on the biological synthesis of the H2O2 and its effect on the upregulation of kinase genes and stress related TFs for imparting stress tolerance.