Membrane remodelling mediates lipopeptide-induced immunity in Arabidopsis.

Bacteria-derived lipopeptides are immunogenic triggers of host defences in metazoans and plants. Root-associated rhizobacteria produce cyclic lipopeptides that activate induced systemic resistance against microbial infection in various plant species. Whether and how these molecules are perceived at the plant cell surface remains elusive. Here we reveal that immune activation in Arabidopsis thaliana by the lipopeptide elicitor surfactin is mediated via a specific interaction with membrane sphingolipids. It relies on host membrane remodelling and subsequent activation of mechanosensitive ion channels. This mechanism leads to host defence potentiation and resistance to the necrotrophic fungus Botrytis cinerea and appears distinct from pattern-triggered immunity induced by classical host pattern recognition receptors. These results reveal a previously uncharacterized mechanism through which lipopeptides derived from non-pathogenic bacteria activate plant immune responses.