Malate Synthase Gene Regulates Vegetative Growth, Spore Germination, Toxin Production, Pathogenicity and Sensitivity to Fungicides in Fusarium graminearum

Abstract

Fusarium graminearum is a fungal pathogen that causes Fusarium head blight (FHB) in wheat. The glyoxylate cycle serves as an essential complement to the tricarboxylic acid (TCA) cycle, critically regulating cellular energy homeostasis and fungal virulence biosynthesis. Nevertheless, the biological functions of glyoxylate cycle-related genes and their regulatory mechanisms in F. graminearum pathogenesis require systematic characterisation. The FgMS knockout mutant ΔFgMS and complemented strain ΔFgMS-C were generated from wild-type F. graminearum strain AY1801 using targeted gene replacement. Compared with AY1801 and ΔFgMS-C, several significant defects were observed in ΔFgMS, which include a reduced growth rate, decreased sporulation, weakened spore germination, diminished virulence, lower toxin production, increased sensitivity to cell wall stress, and reduced sensitivity to carbendazim, pydiflumetofen, difenoconazole, tebuconazole and phenamacril. The dynamic FgMS expression patterns during distinct developmental stages and infection phases were determined by qRT-PCR. FgMS was expressed at a high level during the spore stage. In addition, its expression level increased rapidly as the infection progressed. These findings demonstrate that FgMS is indispensable for vegetative growth, spore formation and germination, virulence and toxin production in F. graminearum.