Novel mode of action of plant defense peptides - hevein-like antimicrobial peptides from wheat inhibit fungal metalloproteases.

TLDR: WAMPs represent novel protease inhibitors that are active against fungal metalloproteases, suggesting that fungalysin plays an important role in fungal development and a novel molecular mechanism of dynamic interplay between host defense molecules and fungal virulence factors is suggested.

Abstract: The multilayered plant immune system relies on rapid recognition of pathogen-associated molecular patterns followed by activation of defense-related genes, resulting in the reinforcement of plant cell walls and the production of antimicrobial compounds To suppress plant defense, fungi secrete effectors, including a recently discovered Zn-metalloproteinase from Fusarium verticillioides, named fungalysin Fv-cmp This proteinase cleaves class IV chitinases, which are plant defense proteins that bind and degrade chitin of fungal cell walls In this study, we investigated plant responses to such pathogen invasion, and discovered novel inhibitors of fungalysin We produced several recombinant hevein-like antimicrobial peptides named wheat antimicrobial peptides (WAMPs) containing different amino acids (Ala, Lys, Glu, and Asn) at the nonconserved position 34 An additional Ser at the site of fungalysin proteolysis makes the peptides resistant to the protease Moreover, an equal molar concentration of WAMP-1b or WAMP-2 to chitinase was sufficient to block the fungalysin activity, keeping the chitinase intact Thus, WAMPs represent novel protease inhibitors that are active against fungal metalloproteases According to in vitro antifungal assays WAMPs directly inhibited hyphal elongation, suggesting that fungalysin plays an important role in fungal development A novel molecular mechanism of dynamic interplay between host defense molecules and fungal virulence factors is suggested