Impaired sterol ester synthesis alters the response of Arabidopsis thaliana to Phytophthora infestans.
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.
Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Weinberg 3, D-06120, Halle (Saale), Germany.
Michaela
M
Kopischke
Lore
L
Westphal
Korbinian
K
Schneeberger
Richard
R
Clark
Stephan
S
Ossowski
Vera
V
Wewer
René
R
Fuchs
Jörn
J
Landtag
Gerd
G
Hause
Peter
P
Dörmann
Volker
V
Lipka
Detlef
D
Weigel
Paul
P
Schulze-Lefert
Dierk
D
Scheel
Sabine
S
Rosahl
D017360:Arabidopsis / Q000235:genetics / Q000382:microbiology*; D004952:Esters / Q000378:metabolism*; D017343:Genes, Plant; D009154:Mutation; D055750:Phytophthora infestans / Q000472:pathogenicity*; D010940:Plant Proteins / Q000378:metabolism; D013261:Sterols / Q000096:biosynthesis*; D013347:Subcellular Fractions / Q000378:metabolism
D004952:Esters; D010940:Plant Proteins; D013261:Sterols