Phenotype MicroArray™ reveals the effects of azoxystrobin on the phenotypic characteristics of Rhizoctonia solani

Abstract

Rhizoctonia solani is a soil-borne pathogen that poses a significant threat to agricultural productivity. Azoxystrobin, a potent fungicide, is extensively utilized for the prevention and control of diseases caused by R. solani. This study evaluated the effects of azoxystrobin (1, 10, and 100 μg/mL) on the substrate utilization patterns and phenotypic characteristics of R. solani using the Phenotype MicroArray™ system. Without azoxystrobin exposure, R. solani demonstrated remarkable metabolic capacity and robust environmental adaptability, utilizing 97.89 % of carbon sources, 98.94 % of nitrogen sources, and 100 % of phosphorus, sulfur, nutrient supplement, and peptide nitrogen sources, growing under 80 (83.33 %) osmotic pressures and 91 (94.79 %) pH conditions. The effect of azoxystrobin on the metabolic capacity of R. solani exhibited a nonlinear correlation with its concentration. At concentrations of 1, 10, and 100 μg/mL, azoxystrobin induced a loss of phenotype in 699, 855, and 862 substrates, and a gain of phenotype in 229, 74, and 68 substrates. The key downregulated KEGG pathways included metabolic pathways, ABC transporters, biosynthesis of secondary metabolites, starch and sucrose metabolism, purine metabolism, and biosynthesis of amino acids, among others. Notably, arbutin and salicin showed significant enhanced metabolic capacity under three azoxystrobin concentrations, involved in glycolysis/gluconeogenesis and phosphotransferase system (PTS), suggesting their role in fungicide response. These findings provide better insights into the adaptability of R. solani and the mechanisms of action of azoxystrobin.