Journal Article

Chitosan inhibits septin-mediated plant infection by the rice blast fungus Magnaporthe oryzae in a protein kinase C and Nox1 NADPH oxidase-dependent manner

Oses-Ruiz, Miriam, Lopez-Llorca, Luis V., Lopez-Moya, Federico, Fricker, Mark D., Were, Vincent M., Martin-Urdiroz, Magdalena, Littlejohn, George, Talbot, Nicholas J.

2021

Overview

• Chitosan is a partially deacetylated linear polysaccharide composed of β-1,4-linked units of D-glucosamine and N-acetyl glucosamine. As well as a structural component of fungal cell walls, chitosan is a potent antifungal agent. However, the mode of action of chitosan is poorly understood. • Here, we report that chitosan is effective for control of rice blast disease. Chitosan application impairs growth of the blast fungus Magnaporthe oryzae and has a pronounced effect on appressorium-mediated plant infection. Chitosan inhibits septin-mediated F-actin remodelling at the appressorium pore, thereby preventing repolarization of the infection cell. • Chitosan causes plasma membrane permeabilization of M. oryzae and affects NADPH oxidase-dependent synthesis of reactive oxygen species, essential for septin ring formation and fungal pathogenicity. We further show that toxicity of chitosan to M. oryzae requires the protein kinase C-dependent cell wall integrity pathway, the Mps1 mitogen-activated protein kinase and the Nox1 NADPH oxidase. A conditionally lethal, analogue (PP1)-sensitive mutant of Pkc1 is partially remediated for growth in the presence of chitosan, while Δnox1 mutants increase their glucan : chitin cell wall ratio, rendering them resistant to chitosan. • Taken together, our data show that chitosan is a potent fungicide which requires the cell integrity pathway, disrupts plasma membrane function and inhibits septin-mediated plant infection.

• Publisher: Wiley,Wiley Subscription Services, Inc
• Subject: Actin / appressoria / Ascomycota / blast disease / Cell walls / Chitin / Chitosan / Chitosan - pharmacology / Disease control / Fungal Proteins - genetics / Fungal Proteins - metabolism / Fungi / Fungicides / Glucan / glucans / Glucosamine / Infections / Integrity / Kinases / Magnaporthe - metabolism / Magnaporthe oryzae / mechanism of action / membrane permeability / membrane permeabilization / Membranes / mitogen-activated protein kinase / Mode of action / Mutants / NAD(P)H oxidase / NAD(P)H oxidase (H2O2-forming) / NADPH oxidase / NADPH Oxidases - genetics / NADPH Oxidases - metabolism / Oryza - metabolism / Oxidase / Pathogenicity / Pathogens / Pkc1 pathway / Plant Diseases / plasma membrane / Polysaccharides / Protein Kinase C / Proteins / Reactive oxygen species / reactive oxygen species (ROS) / Rice / Rice blast / Septin / Septins - genetics / Septins - metabolism / Toxicity