Antimicrobial activity of potato aspartic proteases (StAPs) involves membrane permeabilization

Area of Science:

• Plant biochemistry
• Antimicrobial proteins
• Plant-pathogen interactions

Background:

• Solanum tuberosum aspartic proteases (StAPs) are known to possess antimicrobial properties.
• StAPs are induced in response to various environmental stresses, including pathogen attack.
• The precise mechanism of StAPs' antimicrobial action requires further elucidation.

Purpose of the Study:

• To investigate the direct antimicrobial effect of Solanum tuberosum aspartic proteases (StAPs).
• To determine the mechanism by which StAPs exert their antimicrobial activity against fungal pathogens.
• To assess the interaction of StAPs with spores and hyphae of Fusarium solani and Phytophthora infestans.

Main Methods:

• Viability assays were performed to evaluate the killing effect of StAPs on fungal spores.
• Fluorescently labelled StAPs (FITC-StAPs) were used for localization studies on fungal surfaces.
• Membrane permeabilization was assessed using the SYTOX Green fluorescent dye uptake assay.

Main Results:

• StAPs demonstrated a dose-dependent killing effect on Fusarium solani and Phytophthora infestans spores.
• Localization experiments confirmed direct interaction of StAPs with the surface of fungal spores and hyphae.
• StAP treatment led to significant membrane permeabilization in fungal cells, indicated by SYTOX Green uptake.

Conclusions:

• Solanum tuberosum aspartic proteases (StAPs) possess direct antimicrobial activity against Fusarium solani and Phytophthora infestans.
• The antimicrobial mechanism involves direct interaction with fungal cell surfaces, leading to membrane permeabilization.
• These findings highlight the potential of StAPs as novel agents in plant defense against fungal diseases.