Synthesis of and signalling by small, redox active molecules in the plant immune response

Background: Reactive oxygen and nitrogen intermediates (ROIs and RNIs), respectively, are central features of the plant immune response. Rare, highly reactive protein cysteine (Cys) residues of low pKa are a major target for these intermediates. In this context, S-nitrosylation, the addition of a nitric oxide (NO) moiety to a Cys thiol to form an S-nitrosothiol (SNO), is emerging as a key, redox-based post-translational modification during plant immune function. Methods: Here, we describe some recent insights into how ROIs and RNIs are synthesized and how these small, redox active molecules help orchestrate the plant defence response. Results: The reviewed data highlights the growing importance of ROIs and RNIs in orchestrating the development of plant immunity and provides insights into the molecular mechanisms underpinning their function. General significance: Signalling via small, redox active molecules is a key feature underpinning a diverse series of signal transduction networks in eukaryotic cells. Therefore, insights into the mechanisms that support the activity of these molecules may have potentially wide significance. This article is part of a Special Issue entitled: Regulation of cellular processes by S-nitrosylation.