The mechanisms by which NO is generated are still largely unresolved and elucidation of how it is made by different plant cells in different situations is clearly a research priority. No doubt, NO a ubiquitous bioactive molecule, plays an important role in a broad spectrum of multiple H2O2 mediating physiological processes in plants. NO and H2O2 have now been shown to function as synergistic signals in plants mediating a range of responses to abiotic stresses.