Recognition of pathogen-derived sphingolipids in <i>Arabidopsis</i>.

Abstract

In plants, many invading microbial pathogens are recognized by cell-surface pattern recognition receptors, which induce defense responses. Here, we show that the ceramide <i>Phytophthora infestans</i>-ceramide D (Pi-Cer D) from the plant pathogenic oomycete <i>P. infestans</i> triggers defense responses in <i>Arabidopsis</i>. Pi-Cer D is cleaved by an <i>Arabidopsis</i> apoplastic ceramidase, NEUTRAL CERAMIDASE 2 (NCER2), and the resulting 9-methyl-branched sphingoid base is recognized by a plasma membrane lectin receptor-like kinase, RESISTANT TO DFPM-INHIBITION OF ABSCISIC ACID SIGNALING 2 (RDA2). 9-Methyl-branched sphingoid base is specific to microbes and induces plant immune responses by physically interacting with RDA2. Loss of <i>RDA2</i> or <i>NCER2</i> function compromised <i>Arabidopsis</i> resistance against an oomycete pathogen. Thus, we elucidated the recognition mechanisms of pathogen-derived lipid molecules in plants.