PR002058 (Project)

Description:One of the most important characteristics that plants utilise to successfully defend themselves is the ability to rapidly identify potential threats in the surrounding environment. Plants rely on the perception of microbe-derived molecular pattern chemicals for this recognition, which initiates a number of induced defence reactions that ultimately increase plant resistance. The metabolome acts as a metabolic fingerprint of the biochemical activities that take place in a biological system under particular conditions and therefore provides a functional readout of the cellular mechanisms involved in a biological system. In this study, an untargeted metabolomics approach was applied to decipher the biochemical processes involved in oat plant defence responses to inoculation with various pathovars of Pseudomonas syringae (pathogenic and non-pathogenic on oat) such as P. syringae pv. coronafaciens (Ps-c), -pv. tabaci (Ps-t), -pv. tomato DC3000 (DC3000) and -pv. tomato DC3000 hrcC mutant (hrcC−) and thereby identify signatory markers that are involved in host or nonhost defence responses. At the seedling growth stage, metabolic alterations in the Dunnart oat cultivar (tolerant to Ps-c) in response to inoculation with the respective Pseudomonas syringae pathovars were examined. Following inoculation, plants were monitored for symptom development and harvested at 2-, 4- and 6 d.p.i.. Methanolic metabolite extracts were prepared, and ultra-high-performance liquid chromatography (UHPLC) connected to a qTOF high-definition mass spectrometer was used to analyse the extracts. Chemometric modelling and multivariate statistical analysis revealed host- and time-related metabolic alterations that point to host and nonhost interactions in response to bacterial inoculation/infection. Metabolic profiles from further multivariate data analyses revealed a range of metabolite classes involved in the respective defence responses, including phenolic amides, saponins, phenolic acids, flavonoids, fatty acids, amino acids and alkaloids. The findings in this study allowed the elucidation of metabolic changes involved in oat defence responses to a range of pathovars of Pseudomonas syringae and ultimately contributed to a more comprehensive view of the oat plant metabolism under biotic stress during host vs nonhost interactions.