Nitric oxide in plants - To NO or not to NO

The current knowledge on the occurrence and activity of NO in plants is rev iewed. The multiplicity of nitrogen monoxide species and implications for d ifferentiated reactivity are indicated. Possible sources of NO are evaluate d, and the evidence for the presence of nitric oxide synthase in plants is summarised. The regulatory role of NO. in plant development and in plant in teractions with microorganisms, involving an interplay with other molecules , like ethylene or reactive oxygen species is demonstrated. Finally, some o ther suggestions on potential functions of NO. in plants are indicated. (C) 2000 Elsevier Science Ltd. All rights reserved.