Effective plant defense strategies rely in part on the perception of non-self determinants, so-called microbe-associated molecular patterns (
MAMPs), by transmembrane pattern recognition receptors leading to
MAMP-triggered immunity. Plant resistance against necrotrophic pathogens with a broad host range is complex and yet not well understood. Particularly, it is unclear if resistance to necrotrophs involves pattern recognition receptors. Here, we partially purified a novel proteinaceous elicitor called SCLEROTINIA CULTURE FILTRATE ELICITOR1 (SCFE1) from the necrotrophic fungal pathogen
Sclerotinia sclerotiorum that induces typical
MAMP-triggered immune responses in
Arabidopsis thaliana. Analysis of natural genetic variation revealed five
Arabidopsis accessions (Mt-0, Lov-1, Lov-5, Br-0, and Sq-1) that are fully insensitive to the SCFE1-containing fraction. We used a forward genetics approach and mapped the locus determining SCFE1 sensitivity to
RECEPTOR-LIKE PROTEIN30 (
RLP30). We also show that SCFE1-triggered immune responses engage a signaling pathway dependent on the regulatory receptor-like kinases BRASSINOSTEROID INSENSITIVE1-ASSOCIATED RECEPTOR KINASE1 (BAK1) and SUPPRESSOR OF BIR1-1/EVERSHED (SOBIR1/EVR). Mutants of
RLP30,
BAK1, and
SOBIR1 are more susceptible to
S. sclerotiorum and the related fungus
Botrytis cinerea. The presence of an elicitor in
S. sclerotiorum evoking
MAMP-triggered immune responses and sensed by RLP30/SOBIR1/BAK1 demonstrates the relevance of
MAMP-triggered immunity in resistance to necrotrophic fungi.
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