Novel mode of action of plant defense peptides – hevein‐like antimicrobial peptides from wheat inhibit fungal metalloproteases

Abstract

The multilayered plant immune system relies on rapid recognition of pathogen-associated molecular patterns followed by activation of defenserelated 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.

Dual function of a secreted fungalysin metalloprotease in Ustilago maydis

“…Consistent with our data, Slavokhotova et al . () showed that the inhibition of a F. verticillioides fungalysin by a hevein‐like peptide from wheat results in the inhibition of hyphal elongation, indicating that fungalysin plays a role in fungal development.…”

“…Recently, Sanz-Martin et al (2016) showed that a fungalysin metalloprotease gene (Cgfl) in Colletotrichum graminicola is also involved in fungal virulence on maize, suggesting that chitinase-cleavage activity of fungalysin is required for full virulence. Moreover, it has been shown that inhibition of fungalysin in Fusarium verticillioides by using a wheat hevein-like peptide also inhibits the hyphal elongation, indicating that fungalysin plays a role in fungal development as well (Slavokhotova et al, 2014).…”

A novel antifungal peptide from leaves of the weed Stellaria media L

“…The hevein-like AMPs discovered so far in plants were shown to possess antifungal activity in in vitro assays [32,38,39,[46][47][48][49][50][51][52][53][54]. Binding to chitin and related carbohydrates is supposed to be important for antifungal activity of chitin-binding proteins [55][56][57][58][59].…”

Genetics and genomics of wheat: Storage proteins, ecological plasticity, and immunity

“…The mechanism of action of these peptides was established and consists of the specific inhibition of a metal dependent protein ase of fungi Fusarium Link. A model has been devel oped, according to which, the protective effect of these peptides is due to the inhibition of fungal pro tease, which prevents inactivation of protective the plant chitinases that hydrolyze chitin cell walls of fungi and, thus, inhibit their growth [131].…”