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Arabidopsis ENHANCED DISEASE SUSCEPTIBILITY1 promotes systemic acquired resistance via azelaic acid and its precursor 9-oxo nonanoic acid.

ABSTRACT: Systemic acquired resistance (SAR) is a form of inducible disease resistance that depends on salicylic acid and its upstream regulator ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1). Although local Arabidopsis thaliana defence responses activated by the Pseudomonas syringae effector protein AvrRpm1 are intact in eds1 mutant plants, SAR signal generation is abolished. Here, the SAR-specific phenotype of the eds1 mutant is utilized to identify metabolites that contribute to SAR. To this end, SAR bioassay-assisted fractionation of extracts from the wild type compared with eds1 mutant plants that conditionally express AvrRpm1 was performed. Using high-performance liquid chromatography followed by mass spectrometry, systemic immunity was associated with the accumulation of 60 metabolites, including the putative SAR signal azelaic acid (AzA) and its precursors 9-hydroperoxy octadecadienoic acid (9-HPOD) and 9-oxo nonanoic acid (ONA). Exogenous ONA induced SAR in systemic untreated leaves when applied at a 4-fold lower concentration than AzA. The data suggest that in planta oxidation of ONA to AzA might be partially responsible for this response and provide further evidence that AzA mobilizes Arabidopsis immunity in a concentration-dependent manner. The AzA fragmentation product pimelic acid did not induce SAR. The results link the C9 lipid peroxidation products ONA and AzA with systemic rather than local resistance and suggest that EDS1 directly or indirectly promotes the accumulation of ONA, AzA, or one or more of their common precursors possibly by activating one or more pathways that either result in the release of these compounds from galactolipids or promote lipid peroxidation.

SUBMITTER: Wittek F

PROVIDER: S-EPMC4203127 | biostudies-literature | 2014 Nov

REPOSITORIES: biostudies-literature

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Arabidopsis ENHANCED DISEASE SUSCEPTIBILITY1 promotes systemic acquired resistance via azelaic acid and its precursor 9-oxo nonanoic acid.

Wittek Finni F Hoffmann Thomas T Kanawati Basem B Bichlmeier Marlies M Knappe Claudia C Wenig Marion M Schmitt-Kopplin Philippe P Parker Jane E JE Schwab Wilfried W Vlot A Corina AC

Journal of experimental botany 20140811 20

Systemic acquired resistance (SAR) is a form of inducible disease resistance that depends on salicylic acid and its upstream regulator ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1). Although local Arabidopsis thaliana defence responses activated by the Pseudomonas syringae effector protein AvrRpm1 are intact in eds1 mutant plants, SAR signal generation is abolished. Here, the SAR-specific phenotype of the eds1 mutant is utilized to identify metabolites that contribute to SAR. To this end, SAR bioassay ...[more]

PMID: 25114016

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Project description:We investigated the relationships of the two immune-regulatory plant metabolites salicylic acid (SA) and pipecolic acid (Pip) in the establishment of plant systemic acquired resistance (SAR) in Arabidopsis thaliana induced by the bacterial pathogen Pseudomonas syringae. To characterize the transcriptional SAR response, we used wild-type Col-0 plants, SA-deficient sid2 plants and Pip-deficient ald1 plants and performed RNA-sequencing analyses (Bernsdorff et al., Plant Cell, 2016). SAR establishment in the wild-type is characterized by a strong transcriptional response systemically induced in the foliage that prepares plants for future pathogen attack by pre-activating multiple stages of defense signaling. Whereas systemic Pip elevations are indispensable for SAR and necessary for virtually the whole transcriptional SAR response, a moderate but significant SA-independent component of SAR activation and SAR gene expression is revealed. Arabidopsis thaliana plants were grown individually in pots containing a mixture of soil, vermiculite and sand (8:1:1) in a controlled cultivation chamber with a 10-h day (9 AM to 7 PM; photon flux density 100 mol m-2 s-1) / 14-h night cycle and a relative humidity of 70 %. Day and night temperatures were set to 21C and 18C, respectively. Experiments were performed with 5- to 6-week-old, naive plants exhibiting a uniform appearance. To activate SAR, plants were infiltrated between 10 AM and 12 AM into three lower (1) leaves with suspensions of the bacterial pathogen Pseudomonas syringae pv. maculicola (OD600 = 0.005). Infiltration with 10 mM MgCl2 served as the mock-control treatment. Upper (2) leaves were harvested 48 h after the primary treatment for the determination of systemic gene expression by RNA-seq analyses. Three biologically independent, replicate SAR induction experiments were performed with Col-0 and sid2 plants (experimental set 1), and three other biologically independent experiments with Col-0 and ald1 plants (experimental set 2). In each SAR experiment, at least 6 upper (2) leaves from 6 different plants pre-treated in 1 leaves with Psm (MgCl2) were pooled for one biological Psm- (mock-control) replicate. In this way, 3 biologically independent, replicate samples per treatment and plant genotype were obtained within each SAR set.

Dataset Information

Arabidopsis ENHANCED DISEASE SUSCEPTIBILITY1 promotes systemic acquired resistance via azelaic acid and its precursor 9-oxo nonanoic acid.

Publications

Arabidopsis ENHANCED DISEASE SUSCEPTIBILITY1 promotes systemic acquired resistance via azelaic acid and its precursor 9-oxo nonanoic acid.

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