Plants have a sensitive perception system for the most conserved domain of bacterial flagellin

TLDR

The flagellum is a key virulence factor for bacteria that infect animals and plants. The study shows that plants possess a highly sensitive chemoperception system that targets the most conserved N‑terminal domain of eubacterial flagellin. Synthetic peptides of 15–22 amino acids from this domain trigger defence responses in tomato and other plant species at sub‑nanomolar concentrations. Peptides comprising only the central 8–11 amino acids lack elicitor activity but act as specific competitive inhibitors that suppress plant responses to flagellin, crude bacterial extracts, and live bacteria, revealing a highly sensitive and selective perception system for motile eubacterial flagellin.

Abstract

Summary The flagellum is an important virulence factor for bacteria pathogenic to animals and plants. Here we demonstrate that plants have a highly sensitive chemoperception system for eubacterial flagellins, specifically targeted to the most highly conserved domain within its N terminus. Synthetic peptides comprising 15–22 amino acids of this domain acted as elicitors of defence responses at sub‐nanomolar concentrations in cells of tomato and several other plant species. Peptides comprising only the central 8 to 11 amino acids of the active domain had no elicitor activity but acted as specific, competitive inhibitors in tomato cells. These antagonists suppressed the plant’s response to flagellin, crude bacterial extracts and living bacterial cells. Thus, plants have a highly sensitive and selective perception system for the flagellin of motile eubacteria.