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Impaired sterol ester synthesis alters the response of Arabidopsis thaliana to Phytophthora infestans
Authors:Michaela Kopischke  Lore Westphal  Korbinian Schneeberger  Richard Clark  Stephan Ossowski  Vera Wewer  René Fuchs  Jörn Landtag  Gerd Hause  Peter Dörmann  Volker Lipka  Detlef Weigel  Paul Schulze‐Lefert  Dierk Scheel  Sabine Rosahl
Institution:1. Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, , D‐06120 Halle (Saale), Germany;2. Department of Molecular Biology, Max‐Planck‐Institute for Developmental Biology, , D‐72076 Tübingen, Germany;3. Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, , 53115 Bonn, Germany;4. Department of Plant Cell Biology, Georg‐August‐University G?ttingen, Schwann‐Schleiden Centre, , 37077 G?ttingen, Germany;5. Martin Luther University Halle‐Wittenberg, Biocenter, , D‐06120 Halle (Saale), Germany;6. Max Planck Institute for Plant Breeding Research, , D‐50829 K?ln, Germany
Abstract:Non‐host resistance of Arabidopsis thaliana against Phytophthora infestans, the causal agent of late blight disease of potato, depends on efficient extracellular pre‐ and post‐invasive resistance responses. Pre‐invasive resistance against P. infestans requires the myrosinase PEN2. To identify additional genes involved in non‐host resistance to P. infestans, a genetic screen was performed by re‐mutagenesis of pen2 plants. Fourteen independent mutants were isolated that displayed an enhanced response to Phytophthora (erp) phenotype. Upon inoculation with P. infestans, two mutants, pen2‐1 erp1‐3 and pen2‐1 erp1‐4, showed an enhanced rate of mesophyll cell death and produced excessive callose deposits in the mesophyll cell layer. ERP1 encodes a phospholipid:sterol acyltransferase (PSAT1) that catalyzes the formation of sterol esters. Consistent with this, the tested T‐DNA insertion lines of PSAT1 are phenocopies of erp1 plants. Sterol ester levels are highly reduced in all erp1/psat1 mutants, whereas sterol glycoside levels are increased twofold. Excessive callose deposition occurred independently of PMR4/GSL5 activity, a known pathogen‐inducible callose synthase. A similar formation of aberrant callose deposits was triggered by the inoculation of erp1 psat1 plants with powdery mildew. These results suggest a role for sterol conjugates in cell non‐autonomous defense responses against invasive filamentous pathogens.
Keywords:non‐host resistance  Arabidopsis     Phytophthora infestans     sterol ester  callose  mesophyll
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