ABSTRACT

Abstract.  Soil salinity is one of the major abiotic stresses that threaten sustainable crop production worldwide. In addition to ionic and osmotic stress, salt stress triggers the accumulation of reactive oxygen species (ROS) that can cause oxidative damage to macromolecules, leading to growth retardation or even plant death. Among the various ROS, H2O2 has received the most attention from the scientific community in the last decade. H2O2, a central modulator of stress signal transduction pathways, activates multiple defense responses that reinforce resistance to various abiotic and biotic stresses in plants. Numerous recent studies on plants have confirmed that pre-treatment or priming of seeds or seedlings with appropriate levels of H2O2 can modulate abiotic stress tolerance by regulating multiple stress responsive

pathways. Although much is known about H2O2 mediated salt stress tolerance, little is known about how H2O2 is sensed by plants and how H2O2 induces an inductive pulse that helps to protect plants from salinity stress. In-depth knowledge of the signal transduction pathways associated with H2O2 accumulation is essential if the processes of oxidative signalling and redox regulation of gene expression are to be fully understood in plants under salt stress. In this chapter we summarize the current understanding of H2O2-mediated enhanced salt stress tolerance. We also aim to highlight the signalling roles of H2O2 in salt stress adaptation.