Nitric oxide production mediated by nitrate reductase in plants

Nitric oxide (NO) has emerged as an important signaling molecule in plant growth and development processes and responses to environmental constraints since the last decades. Although the endogenous sources for NO synthesis are still one of the most confounding issues in plant research, nitrate reductase (NR), a key enzyme for nitrogen acquisition by plants, is so far the best characterized enzymatic pathway for NO production and the most important endogenous NO source in plant cells. An update on NO production from NR in plants is provided the overall and recent data about this reductive pathway, by focusing on the modulation of NO production by posttranslational modifications of NR. This chapter also highlights the impact of NO synthesis on nitrate assimilation in plants, as well as the specific involvement of NR-derived NO production, in relation to hormones, in plant growth, and development processes. Although the origin of NO production mediated by abiotic/biotic stresses remains poorly understood and investigated, the main contribution of NR-mediated NO synthesis in plant defense processes, plant-pathogen interactions, and adaptive responses to abiotic stresses are discussed.