Regulation of protein function by reversible S-nitrosation, a post-translational modification based on the attachment of nitroso group to cysteine thiols, has emerged among key mechanisms of NO signalling in plant development and stress responses. S-nitrosoglutathione is regarded as the most abundant low-molecular-weight S-nitrosothiol in plants, where its intracellular concentrations are modulated by S-nitrosoglutathione reductase. We analysed modulations of S-nitrosothiols and protein S-nitrosation mediated by S-nitrosoglutathione reductase in cultivated Solanum lycopersicum (susceptible) and wild Solanum habrochaites (resistant genotype) up to 96 h post inoculation (hpi) by two hemibiotrophic oomycetes, Phytophthora infestans and Phytophthora parasitica. S-nitrosoglutathione reductase activity and protein level were decreased by P. infestans and P. parasitica infection in both genotypes, whereas protein S-nitrosothiols were increased by P. infestans infection, particularly at 72 hpi related to pathogen biotrophy-necrotrophy transition. Increased levels of S-nitrosothiols localised in both proximal and distal parts to the infection site, which suggests together with their localisation to vascular bundles a signalling role in systemic responses. S-nitrosation targets in plants infected with P. infestans identified by a proteomic analysis include namely antioxidant and defence proteins, together with important proteins of metabolic, regulatory and structural functions. Ascorbate peroxidase S-nitrosation was observed in both genotypes in parallel to increased enzyme activity and protein level during P. infestans pathogenesis, namely in the susceptible genotype. These results show important regulatory functions of protein S-nitrosation in concerting molecular mechanisms of plant resistance to hemibiotrophic pathogens.

• Publication type
• Journal Article MeSH

S-nitrosoglutathione reductase (GSNOR) exerts crucial roles in the homeostasis of nitric oxide (NO) and reactive nitrogen species (RNS) in plant cells through indirect control of S-nitrosation, an important protein post-translational modification in signaling pathways of NO. Using cultivated and wild tomato species, we studied GSNOR function in interactions of key enzymes of reactive oxygen species (ROS) metabolism with RNS mediated by protein S-nitrosation during tomato root growth and responses to salinity and cadmium. Application of a GSNOR inhibitor N6022 increased both NO and S-nitrosothiol levels and stimulated root growth in both genotypes. Moreover, N6022 treatment, as well as S-nitrosoglutathione (GSNO) application, caused intensive S-nitrosation of important enzymes of ROS metabolism, NADPH oxidase (NADPHox) and ascorbate peroxidase (APX). Under abiotic stress, activities of APX and NADPHox were modulated by S-nitrosation. Increased production of H2O2 and subsequent oxidative stress were observed in wild Solanumhabrochaites, together with increased GSNOR activity and reduced S-nitrosothiols. An opposite effect occurred in cultivated S. lycopersicum, where reduced GSNOR activity and intensive S-nitrosation resulted in reduced ROS levels by abiotic stress. These data suggest stress-triggered disruption of ROS homeostasis, mediated by modulation of RNS and S-nitrosation of NADPHox and APX, underlies tomato root growth inhibition by salinity and cadmium stress.

• Keywords
• S-nitrosation, S-nitrosoglutathione reductase, Solanum habrochaites, Solanum lycopersicum, abiotic stress, cadmium, nitric oxide, reactive oxygen species, root growth, salinity,
• MeSH
• Aldehyde Oxidoreductases metabolism   MeSH
• Ascorbate Peroxidases metabolism   MeSH
• Benzamides chemistry   metabolism   pharmacology   MeSH
• Sodium Chloride pharmacology   MeSH
• Stress, Physiological MeSH
• Cadmium toxicity   MeSH
• Plant Roots drug effects   growth & development   metabolism   MeSH
• NADPH Oxidases metabolism   MeSH
• Nitrosation MeSH
• Nitric Oxide metabolism   MeSH
• Oxidative Stress drug effects   MeSH
• Hydrogen Peroxide metabolism   MeSH
• Pyrroles chemistry   metabolism   pharmacology   MeSH
• Reactive Nitrogen Species chemistry   metabolism   MeSH
• Reactive Oxygen Species chemistry   metabolism   MeSH
• Gene Expression Regulation, Plant drug effects   MeSH
• Plant Proteins metabolism   MeSH
• S-Nitrosoglutathione pharmacology   MeSH
• S-Nitrosothiols metabolism   MeSH
• Solanum lycopersicum drug effects   growth & development   metabolism   MeSH
• Solanum growth & development   metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Aldehyde Oxidoreductases MeSH
• Ascorbate Peroxidases MeSH
• Benzamides MeSH
• Sodium Chloride MeSH
• formaldehyde dehydrogenase, glutathione-independent MeSH Browser
• Cadmium MeSH
• N6022 MeSH Browser
• NADPH Oxidases MeSH
• Nitric Oxide MeSH
• Hydrogen Peroxide MeSH
• Pyrroles MeSH
• Reactive Nitrogen Species MeSH
• Reactive Oxygen Species MeSH
• Plant Proteins MeSH
• S-Nitrosoglutathione MeSH
• S-Nitrosothiols MeSH