Regulation and Turnover of Nitric Oxide by Phytoglobins in Plant Cell Responses

Abstract

The involvement of phytoglobins in the metabolism of nitric oxide (NO) and reactive nitrogen species (RNS) produced during stress, plant growth, and development is discussed. The action of phytoglobin expression upon NO leads to the maintenance of redox status, minimization of the damage from reactive oxygen and nitrogen species in the cytoplasm of the cell, and regulation of hor-monal and stress responses. NO scavenging is achieved via phytoglobins, and it can also involve S-nitrosoglutathione reductase and a direct interaction of NO with superoxide anion followed by detoxification of formed peroxynitrite. The interplay between these pathways results in flexible change of NADH/NAD + ratios, gluta-thione potential, and the level of nitrosylation of proteins. The system of production and detoxification of RNS is linked to morphogenetic events such as relief of dormancy, aerenchyma formation, etc. Due to the mobility of both NO and phyto-hormones, plants developed strategies to regulate specific cell hormonal actions to permit differentiation during development and to respond to stress. Phytoglobins are the agents responsible for differential cellular responses to hormones that use NO as a signal transduction factor. 1 Nitric Oxide as a Gasotransmitter Nitric oxide is involved in many plant processes, including stress responses, pathogen resistance, and plant development. In this chapter, we will examine these processes in relation to the NO reaction with phytoglobins regulating the redox control which influences phytohormone production and signalling. The