Role of Nitric oxide in regulation of H2O2 mediating tolerance of plants to abiotic stress: A synergistic signalling approach

The relationship between abiotic stress, nitric oxide (NO) and Hydrogen peroxide (H2O2) is a challenging one. It is now clear that H2O2 and NO function as signalling molecules in plants. A wide range of abiotic stresses results in H2O2 generation, from a variety of sources and it has many essential roles in plant metabolism but at the same time, accumulation related to virtually any environmental stress is potentially damaging. NO is gaining increasing attention as a regulator of diverse pathophysiological processes in plant science, mainly due to its properties (free radicals, small size, no charge, short-lived, and highly diffusible across biological membranes) and multifunctional roles in plant growth, development and regulation of remarkably broad myriad of plant cellular mechanisms. Various abiotic stresses can induce NO synthesis, but its origin and mode of action in plants have not yet been completely resolved. Recent studies on NO production have tended to high light the questions that still remain unanswered rather than telling us more about NO metabolism. But regarding NOH2O2 signalling and functions, new findings have given an impression of the intricacy of NO-H 2O2 related signalling networks against abiotic stresses. Cellular responses to NO-H2O2 are complex, with considerable cross-talk between responses to several abiotic stresses. In last few years, the role of NO in H2O2 mediating tolerance in plants to abiotic stress has established much consideration.