Cellular Responses Required for Oxidative Stress Tolerance of the Necrotrophic Fungus Alternaria alternata, Causal Agent of Pear Black Spot

Miao Zhang; Yandong Zhang; Yongcai Li; Yang Bi; Renyan Mao; Yangyang Yang; Qianqian Jiang; Dov Prusky

doi:10.3390/microorganisms10030621

Cellular Responses Required for Oxidative Stress Tolerance of the Necrotrophic Fungus Alternaria alternata, Causal Agent of Pear Black Spot

Microorganisms. 2022 Mar 15;10(3):621. doi: 10.3390/microorganisms10030621.

Authors

Miao Zhang¹, Yandong Zhang¹, Yongcai Li¹, Yang Bi¹, Renyan Mao¹, Yangyang Yang¹, Qianqian Jiang¹, Dov Prusky²

Affiliations

¹ College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, China.
² Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, Rishon LeZion 50250, Israel.

Abstract

To establish successful infections in host plants, pathogenic fungi must sense and respond to an array of stresses, such as oxidative stress. In this study, we systematically analyzed the effects of 30 mM H₂O₂ treatment on reactive oxygen species (ROS) metabolism in Alternaria alternata. Results showed that 30 mM H₂O₂ treatment lead to increased O^2- generation rate and H₂O₂ content, and simultaneously, increased the activities and transcript levels of NADPH oxidase (NOX). The activities and gene expression levels of enzymes related with ascorbic acid-glutathione cycle (AsA-GSH cycle) and thioredoxin systems, including superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), ascorbate peroxidase (AXP) and thioredoxin (TrxR), were remarkably enhanced by 30 mM H₂O₂ stress treatment. Additionally, 30 mM H₂O₂ treatment decreased the glutathione (GSH) content, whereas it increased the amount of oxidized glutathione (GSSG), dehydroascorbate (DHA) and ascorbic acid (AsA). These results revealed that cellular responses are required for oxidative stress tolerance of the necrotrophic fungus A. alternata.

Keywords: Alternaria alternata; AsA-GSH cycle; oxidative stress; redox balance; thioredoxin system.