The peach (Prunus persica) defensin PpDFN1 displays antifungal activity through specific interactions with the membrane lipids

Abstract

Ppdfn1 is a defensin gene previously identified in peach (Prunus persica). The biological role of Ppdfn1 was investigated by analysing its expression profile in leaves, flowers and fruits, either inoculated with the Monilinia laxa fungal pathogen or mock‐inoculated. Ppdfn1 expression was highest in flowers and, in fruits, did not vary upon M. laxa inoculation. To characterize the PpDFN1 antifungal activity, the recombinant mature peptide was expressed in Escherichia coli and purified; recombinant PpDFN1 displays antifungal activity against Botrytis cinerea, M. laxa and Penicillium expansum, with IC50 values of 15·1, 9·9 and 1·1 μg mL−1, respectively. Treatment of fungal hyphae with FITC‐labelled PpDFN1 indicated that the peptide is not internalized by fungal hyphae, but localizes on their external cell surface. At this site, PpDFN1 is capable of membrane destabilization and permeabilization, as demonstrated by SYTOX Green fluorescence uptake by the treated mycelia. Using artificial lipid monolayers, it was shown that PpDFN1 interacts with sphingolipid‐containing membranes; however the strongest interaction occurs with monolayers composed of lipids extracted from sensitive fungi, such as P. expansum. These data suggest that the lipid composition of fungal membranes is of key relevance for defensin specificity.

Metagenomics analysis of microbial communities associated with a traditional rice wine starter culture (Xaj-pitha) of Assam, India

“…However, any stimulatory or inhibitory effects of these plant parts are yet to be tested. Nonetheless, Ppdfn1, a defensin protein, from Prunus persica (common name peach) shows antifungal activity against pathogens, such as Botrytis cinerea , Monilinia laxa , and Penicillium expansum (Nanni et al 2013 ). Interestingly, phyllosphere of Setaria italica has been reported to harbor some of the dominant fungi, such as Rhizopus nigricans , Curvularia pallescens , Aspergillus flavus , A. fumigatus , and Trichoderma album (Upadhyaya and Gupta 2009 ).…”

Maize EMBRYO SAC family peptides interact differentially with pollen tubes and fungal cells

“…However, inhibition of cereal rust fungi, for example, is usually achieved by defensins NaD1 and NaD2 from flowers of tobacco ( N. alata ) at a concentration of 1–2 µM ( Dracatos et al , 2014 ). Peach ( Prunus persica ) defensin DFN1 also displayed antifungal activity at 1 µM through specific interactions with membrane lipids of Botrytis cinerea , Penicillium expansum , and Monilinia laxa ( Nannia et al , 2012 ). These findings indicate that ES peptides have lost most of their antifungal activity.…”

VvAMP2, a grapevine flower‐specific defensin capable of inhibiting Botrytis cinerea growth: insights into its mode of action

“…On the other hand, the lack of antimicrobial activity of VvAMP2 against other fungal species suggests that other non-ionic components could play a role in VvAMP2 recognition of its target. Specific lipid components on the fungal membrane and cell wall have been recognized to act as receptors for a number of plant defensins, such as RsAFP2, DmAMP1, MsDef1, PsD1, sugarcane Sd5 and peach PpDFN1 (Wilmes et al, 2011;Nanni et al, 2013).…”