Nitric Oxide Synthase‐Like Activities in Plants

Abstract

Nitric oxide (NO) is a gaseous radical molecule that has long been considered to be a harmful air pollutant produced through anthropogenic activities. The finding in the late 1980s that the gas is synthesized in animal cells by the enzyme nitric oxide synthase (NOS) led to a paradigm shift in bioscience. NO is now recognized as an endogenous signalling molecule involved in diverse physiological processes. Plants and algae also produce NO, but the mechanism of synthesis remains controversial. A number of inhibitor experiments have suggested the presence of NOS‐like activities in plants and algae. To date, however, there is no conclusive evidence for the presence of NOS enzymes in these organisms. This chapter provides an overview of plant NOS research, along with a description of possible arginine‐dependent signal transduction mechanisms in plants.