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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 #355159

Research Project: Genetic and Environmental Factors Controlling Aflatoxin Biosynthesis

Location: Food and Feed Safety Research

Title: The bZIP transcription factor Afap1 mediates oxidative stress response and aflatoxin biosynthesis in Aspergillus flavus

item GUAN, XUANLI - Ministry Of Agriculture - China
item ZHAO, YUEJU - Ministry Of Agriculture - China
item LIU, XIAO - Ministry Of Agriculture - China
item SHANG, BO - Ministry Of Agriculture - China
item XING, FUGUO - Ministry Of Agriculture - China
item ZHOU, LU - Ministry Of Agriculture - China
item WANG, YAN - Ministry Of Agriculture - China
item ZHANG, CHUSHU - Ministry Of Agriculture - China
item Bhatnagar, Deepak
item LIU, YANG - Ministry Of Agriculture - China

Submitted to: Revista Argentina de Microbiología
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary: Aflatoxins (AFs) are carcinogenic secondary metabolites produced by the fungi Aspergillus flavus (and other Aspergillus spp.) on crops such as corn, cotton and peanut and in treatments prior to harvest. AFs can seriously endanger the health of humans and animals when contaminated commodities are consumed. Therefore, it is important to limit such contamination by developing a good understanding of the AF biosynthetic process. There is evidence that oxidative stress is closely related to AF biosynthesis. We have found a gene in the toxin producing fungus that appears to be related to oxidative stress and seems to be involved in the regulation of aflatoxin production by the fungus. This gene may be responding to environmental signals, and may provide insights into why different fungal strains produce different levels of toxin in the field.

Technical Abstract: Aflatoxin is carcinogenic secondary metabolites produced mainly by Aspergillus flavus and Aspergillus parasiticus and can seriously endanger the health of humans and animals. Oxidative stress is a common defense response, and reactive oxygen species (ROS) can induce a series of secondary metabolites, including aflatoxin. The treatment of different oxidative stress on toxigenic A. flavus strain CA14PTs demonstrated that the growth of strain was significantly inhibited by the increased H2O2 and was completely inhibited at 40 mmol/l. However, for quantitative analysis of aflatoxin production, HPLC showed that AFB1 concentration was increased by the increased H2O2 concentration until 10 mmol/l. By NCBI BLAST analysis, Afap1, a basic leucine zipper (bZIP) transcription factor, was presumed to be a transcription factor associated with oxidative stress. Treatment of 5 mmol/l H2O2 completely inhibited the growth of afap1 mutants but did not affect the growth of CA14PTs. In addition, it showed that AFB1 concentration in 'afap1 was only about one fourth that of CA14PTs. These results suggested that Afap1 plays a key role in regulation of oxidative stress and aflatoxin production in A. flavus.