Updates on the Functions and Molecular Mechanisms of the Genes Involved in Aspergillus flavus Development and Biosynthesis of Aflatoxins

Abstract

Aspergillus flavus (A. flavus) is a ubiquitous and opportunistic fungal pathogen that causes invasive and non-invasive aspergillosis in humans and animals. This fungus is also capable of infecting a large number of agriculture crops (e.g., peanuts, maze, cotton seeds, rice, etc.), causing economic losses and posing serious food-safety concerns when these crops are contaminated with aflatoxins, the most potent naturally occurring carcinogens. In particular, A. flavus and aflatoxins are intensely studied, and they continue to receive considerable attention due to their detrimental effects on humans, animals, and crops. Although several studies have been published focusing on the biosynthesis of the aforementioned secondary metabolites, some of the molecular mechanisms (e.g., posttranslational modifications, transcription factors, transcriptome, proteomics, metabolomics and transcriptome, etc.) involved in the fungal development and aflatoxin biosynthesis in A. flavus are still not fully understood. In this study, a review of the recently published studies on the function of the genes and the molecular mechanisms involved in development of A. flavus and the production of its secondary metabolites is presented. It is hoped that the information provided in this review will help readers to develop effective strategies to reduce A. flavus infection and aflatoxin production.

A Simple CRISPR/Cas9 System for Efficiently Targeting Genes of Aspergillus Section Flavi Species, Aspergillus nidulans, Aspergillus fumigatus, Aspergillus terreus, and Aspergillus niger

“…Incorporation of donor DNA in both cases likely would significantly increase transformation frequencies. In more than a decade, over 100 A. flavus genes have been disrupted by several research groups ( 3 , 5 ). These gene function studies were carried out nearly exclusively using NHEJ-deficient strains ( 24 , 36 ).…”

“…The S-type isolates produce many small sclerotia but conidiate poorly, whereas the L-type isolates produce few, large sclerotia or none but abundant conidia on most agar media ( 4 ). Extensive studies on aflatoxin production and asexual development have been conducted ( 3 , 5 , 6 ).…”

Role of RNA Modifications, Especially m6A, in Aflatoxin Biosynthesis of Aspergillus flavus

“…40−43 Besides, signal pathways, transcriptome, and metabolomics involved in morphogenesis and aflatoxin production also have been extensively studied. 44 Among the many biotic and abiotic factors, temperature has been reported previously to heavily influence the aflatoxin formation. 45 The mechanism of temperature that affects the growth of A. flavus and aflatoxin production has been widely studied.…”

Histone deacetylase SirE regulates development, DNA damage response and aflatoxin production in Aspergillus flavus

“…Aflatoxins also cause mass destructions of food crops annually and limit the development of international trade, which pose huge commercial losses worldwide (Amaike & Keller, 2011). To limit the adverse effects, most countries have strict regulations outlining the acceptable ranges of aflatoxins contamination of imported crops, especially AFB 1 , to protect their populations and promote food and feed safety (Sirma et al, 2018;van Egmond et al, 2007). Therefore, minimizing aflatoxin exposure and clarifying the mechanisms of aflatoxin synthesis and metabolism pathway remain pressing issues, which could improve food security and increase economic benefits.…”

“…Currently, lysine acetylation is one of the most well‐defined modifications and plays an important role in the development, secondary metabolism and pathogenicity of A. flavus . (Tumukunde et al, 2021; Yang et al, 2019). The protein acetylation level includes two enzyme families, lysine acetyltransferases (KATs) and lysine deacetylases (KDACs) (Wassano et al, 2020).…”