15 research outputs found

    Plasma Membrane-Associated Proteins Identified in Arabidopsis Wild Type, <i>lbr2-2</i> and <i>bak1-4</i> Mutants Treated with LPSs from <i>Pseudomonas</i> <i>syringae</i> and <i>Xanthomonas campestris</i>

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    Plants recognise bacterial microbe-associated molecular patterns (MAMPs) from the environment via plasma membrane (PM)-localised pattern recognition receptor(s) (PRRs). Lipopolysaccharides (LPSs) are known as MAMPs from gram-negative bacteria that are most likely recognised by PRRs and trigger defence responses in plants. The Arabidopsis PRR(s) and/or co-receptor(s) complex for LPS and the associated defence signalling remains elusive. As such, proteomic identification of LPS receptors and/or co-receptor complexes will help to elucidate the molecular mechanisms that underly LPS perception and defence signalling in plants. The Arabidopsis LPS-binding protein (LBP) and bactericidal/permeability-increasing protein (BPI)-related-2 (LBR2) have been shown to recognise LPS and trigger defence responses while brassinosteroid insensitive 1 (BRI1)-associated receptor kinase 1 (BAK1) acts as a co-receptor for several PRRs. In this study, Arabidopsis wild type (WT) and T-DNA knock out mutants (lbr2-2 and bak1-4) were treated with LPS chemotypes from Pseudomonas syringae pv. tomato DC3000 (Pst) and Xanthomonas campestris pv. campestris 8004 (Xcc) over a 24 h period. The PM-associated protein fractions were separated by liquid chromatography and analysed by tandem mass spectrometry (LC-MS/MS) followed by data analysis using ByonicTM software. Using Gene Ontology (GO) for molecular function and biological processes, significant LPS-responsive proteins were grouped according to defence and stress response, perception and signalling, membrane transport and trafficking, metabolic processes and others. Venn diagrams demarcated the MAMP-responsive proteins that were common and distinct to the WT and mutant lines following treatment with the two LPS chemotypes, suggesting contributions from differential LPS sub-structural moieties and involvement of LBR2 and BAK1 in the LPS-induced MAMP-triggered immunity (MTI). Moreover, the identification of RLKs and RLPs that participate in other bacterial and fungal MAMP signalling proposes the involvement of more than one receptor and/or co-receptor for LPS perception as well as signalling in Arabidopsis defence responses

    Metabolomic Evaluation of Tissue-Specific Defense Responses in Tomato Plants Modulated by PGPR-Priming against Phytophthora capsici Infection

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    Plant growth-promoting rhizobacteria (PGPR) can stimulate disease suppression through the induction of an enhanced state of defense readiness. Here, untargeted ultra-high performance liquid chromatography–mass spectrometry (UHPLC–MS) and targeted ultra-high performance liquid chromatography coupled to triple-quadrupole mass spectrometry (UHPLC–QqQ-MS) were used to investigate metabolic reprogramming in tomato plant tissues in response to priming by Pseudomonas fluorescens N04 and Paenibacillus alvei T22 against Phytophthora capsici. Roots were treated with the two PGPR strains prior to stem inoculation with Ph. capsici. Metabolites were methanol-extracted from roots, stems and leaves at two–eight days post-inoculation. Targeted analysis by UHPLC–QqQ-MS allowed quantification of aromatic amino acids and phytohormones. For untargeted analysis, UHPLC–MS data were chemometrically processed to determine signatory biomarkers related to priming against Ph. capsici. The aromatic amino acid content was differentially reprogrammed in Ps. fluorescens and Pa. alvei primed plants responding to Ph. capsici. Furthermore, abscisic acid and methyl salicylic acid were found to be major signaling molecules in the tripartite interaction. LC–MS metabolomics analysis showed time-dependent metabolic changes in the primed-unchallenged vs. primed-challenged tissues. The annotated metabolites included phenylpropanoids, benzoic acids, glycoalkaloids, flavonoids, amino acids, organic acids, as well as oxygenated fatty acids. Tissue-specific reprogramming across diverse metabolic networks in roots, stems and leaves was also observed, which demonstrated that PGPR priming resulted in modulation of the defense response to Ph. capsici infection

    Metabolomic evaluation of tissue specific defense responses in tomato plants modulated by PGPR-priming against Phytophthora capsici infection

    No full text
    Plant growth-promoting rhizobacteria (PGPR) can stimulate disease suppression through the induction of an enhanced state of defense readiness. Here, untargeted ultra-high performance liquid chromatography–mass spectrometry (UHPLC–MS) and targeted ultra-high performance liquid chromatography coupled to triple-quadrupole mass spectrometry (UHPLC–QqQ-MS) were used to investigate metabolic reprogramming in tomato plant tissues in response to priming by Pseudomonas fluorescens N04 and Paenibacillus alvei T22 against Phytophthora capsici. Roots were treated with the two PGPR strains prior to stem inoculation with Ph. capsici. Metabolites were methanol-extracted from roots, stems and leaves at two–eight days post-inoculation. Targeted analysis by UHPLC–QqQMS allowed quantification of aromatic amino acids and phytohormones. For untargeted analysis, UHPLC–MS data were chemometrically processed to determine signatory biomarkers related to priming against Ph. capsici. The aromatic amino acid content was differentially reprogrammed in Ps. fluorescens and Pa. alvei primed plants responding to Ph. capsici. Furthermore, abscisic acid and methyl salicylic acid were found to be major signaling molecules in the tripartite interaction. LC– MS metabolomics analysis showed time-dependent metabolic changes in the primed-unchallenged vs. primed-challenged tissues. The annotated metabolites included phenylpropanoids, benzoic acids, glycoalkaloids, flavonoids, amino acids, organic acids, as well as oxygenated fatty acids. Tissue-specific reprogramming across diverse metabolic networks in roots, stems and leaves was also observed, which demonstrated that PGPR priming resulted in modulation of the defense response to Ph. capsici infection.The South African National Research Foundationhttp://www.mdpi.com/journal/plantspm2022Plant Production and Soil Scienc

    Comparative Metabolic Phenotyping of Tomato (Solanum lycopersicum) for the Identification of Metabolic Signatures in Cultivars Differing in Resistance to Ralstonia solanacearum

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    Tomato (Solanum lycopersicum) is an important dietary source which contains numerous bioactive phytochemicals. Active breeding programs constantly produce new cultivars possessing superior and desirable traits. However, the underlying molecular signatures that functionally describe these traits are yet to be elucidated. Thus, in this study we used an untargeted metabolomic approach to describe differential metabolic profiles of four cultivars described as having high to intermediate resistance to Ralstonia solanacearum. Metabolites were methanol-extracted from leaves, stems and root tissues and analyzed by liquid chromatography coupled with high definition mass spectrometry. Multivariate data analysis revealed cultivar-related differential metabolic phenotypes. A total of 41 metabolites were statistically selected and annotated, consisting of amino acids, organic acids, lipids, derivatives of cinnamic acid and benzoic acids, flavonoids and steroidal glycoalkaloids which were especially prominent in the two highly resistant cultivars. Interestingly, the less resistant cultivars had various fatty acid derivatives in root extracts that contributed to the differentiated metabolic signatures. Moreover, the metabolic phenotype of the STAR9008 (8SC) cultivar with intermediate resistance, was characterized by derivatives of cinnamic acids and flavonoids but at lower levels compared to the resistant cultivars. The 8SC cultivar also exhibited a lack of hydroxybenzoic acid biomarkers, which may be attributed to its lower resistance. These metabolic phenotypes provide insights into the differential metabolic signatures underlying the metabolism of these four cultivars, defining their respective phenotypic traits such as their resistance, tolerance or susceptibility to Ralstonia solanacearum
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