Molecular Mechanism of Aflatoxin B1 Synthesis Related AfVerB Regulating the Development, AFB1 Biosyntheis and Virulence of Aspergillus flavus Mainly Through Its CYP Domain

TL;DR

This study explores how the AfVerB protein in Aspergillus flavus affects fungal development, aflatoxin production, and virulence, mainly through its CYP domains.

Contribution

The study reveals the role of AfVerB's CYP domains in regulating aflatoxin biosynthesis, fungal development, and virulence in Aspergillus flavus.

Findings

AfVerB's CYP domains are crucial for fungal morphogenesis and aflatoxin synthesis.

AfVerB is essential for host infection and response to environmental stress.

The second CYP domain of AfVerB is particularly important for its biological functions.

Abstract

Aspergillus flavus and its secondary metabolites aflatoxins pose a significant threat to the health of humans, animals, and plants. Therefore, there is an urgent need to control A. flavus contamination. AfverB plays a key role in the aflatoxin gene cluster; however, its function and mechanism in fungal development and virulence remain poorly understood. In this study, we constructed afVerB gene deletion mutants (∆afVerB−1 and ∆afVerB−2) and two CYP domain mutants (afVerB∆D1 and afVerB∆D2) through homologous recombination. Phenotype analysis revealed that, via its two CYP domains, AfVerB is deeply involved in fungal morphogenesis and aflatoxin synthesis. Insect and crop colonization models revealed that AfVerB plays a key role in the fungus’s ability to infect hosts, and stress experiments discovered that AfVerB plays a significant role in the response to various environmental stresses, which explains why AfVerB is a key factor in fungal infection to some extent. RT-qPCR analysis demonstrated that AfVerB performs its bio-function through corresponding regulatory factors. We ultimately discovered that AfVerB is deeply involved in cell membrane stress stability, thereby participating in the regulation of fungal drug resistance (sensitive to AMB and resistant to VOR in this study). The CYP domain of AfVerB, particularly its second CYP domain, is crucial for the execution of its biological functions. This study elucidated the regulatory mechanisms by which AfVerB regulates fungal pathogenicity and aflatoxin biosynthesis, providing potential strategies for controlling A. flavus and its aflatoxin contamination.

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