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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Food and Feed Safety Research » Research » Publications at this Location » Publication #385950

Research Project: Aflatoxin Control through Identification of Intrinsic and Extrinsic Factors Governing the Aspergillus Flavus-Corn Interaction

Location: Food and Feed Safety Research

Title: New insights of transcriptional regulator AflR in Aspergillus flavus physiology

item WANG, PENG - Ocean University Of China
item XU, JIA - Ocean University Of China
item Chang, Perng Kuang
item LIU, ZHEMIN - Ocean University Of China
item KONG, QING - Ocean University Of China

Submitted to: Microbiology Spectrum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/22/2021
Publication Date: 1/26/2022
Citation: Wang, P., Xu, J., Chang, P.-K., Liu, Z., Kong, Q. 2022. New insights of transcriptional regulator AflR in Aspergillus flavus physiology. Microbiology Spectrum. 10(1). Article e00791-21.

Interpretive Summary: The mold Aspergillus flavus is a major producer of the carcinogenic aflatoxins. These toxins pose a great risk to human and animal health. Aflatoxin biosynthesis is known to be tightly regulated and linked to fungal growth and development. To better understand the molecular mechanisms that underlie aflatoxin production, we knocked out a critical regulatory gene that is directly involved in aflatoxin production. Impairment of this gene not only severely decreased expression of aflatoxin pathway genes but also those important for development and dissemination. This information along with uses of other preventive strategies, such as biocontrol and breeding of host plant resistance may help to alleviate aflatoxin contamination of crops.

Technical Abstract: Aspergillus flavus aflR, a gene encoding a transcription factor with a Zn(II)2Cys6 DNA-binding domain, is critical for aflatoxin biosynthesis. AflR binding sites are present in promoter regions of clustering genes, and they also are found outside the aflatoxin gene cluster. To understand the overall effect of aflR on genome-wide gene expression, we knocked out aflR in A. flavus. The mutant cultured in YES medium for 5 days produced 1000-fold lower amounts of aflatoxins B1 and B2 than those produced by wild-type A. flavus. This aflR gene disruption also negatively affected the mutant strain’s ability to grow and to produce asexual propagules such as conidia and sclerotia in time-course experiments. Transcriptomic analysis of the mutant grown on potato dextrose agar plates at 0 h, 24 h and 72 h showed that expression of clustering genes involved in aflatoxin biosynthesis was significantly down-regulated. Additionally, gene ontology (GO) and KEGG pathway analyses indicated that many genes including those involved in spore germination, sclerotial development, and carbohydrate metabolism were also down-regulated. Therefore, A. flavus AflR not only regulates aflatoxin biosynthesis but also has an extended role in fungal growth and development.