Regulation of Fungal Morphogenesis and Pathogenicity of Aspergillus flavus by Hexokinase AfHxk1 through Its Domain Hexokinase_2

Abstract

As a filamentous pathogenic fungus with high-yield of aflatoxin B1, Aspergillus flavus is commonly found in various agricultural products. It is crucial to develop effective strategies aimed at the prevention of the contamination of A. flavus and aflatoxin. Hexokinase AfHxk1 is a critical enzyme in fungal glucose metabolism. However, the role of AfHxk1 in A. flavus development, aflatoxin biosynthesis, and virulence has not yet been explored. In this study, afHxk1 gene deletion mutant (ΔafHxk1), complementary strain (Com-afHxk1), and the domain deletion strains (afHxk1ΔD1 and afHxk1ΔD2) were constructed by homologous recombination. Phenotype study and RT-qPCR revealed that AfHxk1 upregulates mycelium growth and spore and sclerotia formation, but downregulates AFB1 biosynthesis through related classical signaling pathways. Invading models and environmental stress analysis revealed that through involvement in carbon source utilization, conidia germination, and the sensitivity response of A. flavus to a series of environmental stresses, AfHxk1 deeply participates in the regulation of pathogenicity of A. flavus to crop kernels and Galleria mellonella larvae. The construction of domain deletion strains, afHxk1ΔD1 and afHxk1ΔD2, further revealed that AfHxk1 regulates the morphogenesis, mycotoxin biosynthesis, and the fungal pathogenicity mainly through its domain, Hexokinase_2. The results of this study revealed the biological role of AfHxk1 in Aspergillus spp., and might provide a novel potential target for the early control of the contamination of A. flavus.