Metabolic Response of Tomato Leaves Upon Different Plant-Pathogen Interactions

Introduction - Plants utilise vaious defence mechanisms against their potential biotic stressing agents such as viroids, viruses, bacteria or fungi and abiotic environmental challenges. Among them metabolic alteration is a common response in both compatible and incompatible plant-pathogen interactions. However, the identification of metabolic changes associated with defence response is not an easy task due to the complexity of the metabolome and the plant response. To address the problem of metabolic complexity, a metabolomics approach was employed in this study. Objective - To identify a wide range of pathogen (citrus exocortis viroid, CEVd, or Pseudomonas syringae pv. tomato)-induced metabolites of tomato using metabolomics. Methodology - Nuclear magnetic resonance (NMR) spectroscopy in combination with multivariate data analysis were performed to analyse the metabolic changes implicated in plant-pathogen interaction. Results - NMR-based metabolomics of crude extracts allowed the identification of different metabolites implicated in the systemic (viroid) and hypersensitive response (bacteria) in plant-pathogen interactions. While glycosylated gentisic acid was the most important induced metabolite in the viroid infection, phenylpropanoids and a flavonoid (rutin) were found to be associated with bacterial infection. Conclusions - NMR metabolomics is a potent platform to analyse the compounds involved in different plant infections. A broad response to different pathogenic infections was revealed at metabolomic levels in the plant. Also, metabolic specificity against each pathogen was observed. Copyright (C) 2009 John Wiley & Sons, Ltd.