NITRIC OXIDE IN PLANTS: PROPERTIES, BIOSYNTHESIS AND PHYSIOLOGICAL FUNCTIONS

Nitric oxide (NO) is an important signalling molecule with diverse physiological functions in plants. In the last years, many advances have been obtained regarding NO synthesis and its physiological effects in plants. It was found to play a crucial role in plant growth and development, starting from germination to flowering, ripening of fruit and senescence of organs, respiratory metabolism, as well as plant response to abiotic and biotic stressors. However, the molecular mechanisms underlying its effects remain poorly understood. This review discusses some aspects related to NO in plants, such as chemical properties, synthesis pathways, antioxidant action, physiological and biochemical changes that occur in plants under normal conditions and the possible functions of NO under changing environmental conditions. The interaction of NO with plant hormones, and cross-talk with salicylic acid are also discussed. The elucidation of such aspects represents a challenge to future studies.