Nitric oxide as a signaling molecule in plants

Nitric oxide is an important signaling molecule in plant responses to biotic and abiotic stress. Many workers have implicated NO for biotic and abiotic responses in plant and have mainly used NO scavengers, PTIO and cPTIO, and NOS inhibitors, L-NAME, L-NIL and L- NMMA to substantiate its role in these processes. A number of NO biosynthetic pathways have been proposed but the molecular mechanisms underlying them are poorly understood. While different approaches have been used to acertain the role of NO, the methods used are widely debated. This review discusses the various NO sources, its chemical nature and role in plant responses to biotic and abiotic stresses.