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Molecular characterization of atoxigenic Aspergillus flavus isolates collected in China
Dandan Wei1, Lu Zhou, Jonathan Nimal Selvaraj
1Institute of Agro-products Processing Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-products Processing, Ministry of Agriculture, Beijing, 100193, P. R. China.
Abstract:
Aspergillus flavus strains were isolated from peanut fields of Liaoning, Shandong, Hubei and Guangdong Provinces in China, and identified through phenotypic and molecular approaches. Of the 323 A. flavus strains isolated, 76 strains did not produce aflatoxins detectable by UPLC. The incidence of atoxigenic A. flavus strains decreased with increase in temperature and increased with increase in latitude in different geographical locations. Amplification of all the aflatoxin genes in the aflatoxin gene cluster in the atoxigenic isolates showed that there were 25 deletion patterns (A-Y), with 22 deletion patterns identified for the first time. Most of the atoxigenic A. flavus isolates with gene deletions (97%) had deletions in at least one of the four genes (aflT, nor-1, aflR, and hypB), indicating that these four genes could be targeted for rapid identification of atoxigenic strains. The atoxigenic isolates with gene deletions, especially the isolates with large deletions, are potential candidates for aflatoxin control.
Insights
Researchers identified 76 atoxigenic Aspergillus flavus strains from Chinese peanut fields. These strains, lacking aflatoxin production due to gene deletions, show promise for biological control strategies.
Area of Science:
- Agricultural Microbiology
- Mycotoxicology
Background:
- Aspergillus flavus is a significant contaminant of food crops, producing harmful aflatoxins.
- Understanding the genetic basis of atoxigenicity in A. flavus is crucial for developing control strategies.
Purpose of the Study:
- To isolate and characterize atoxigenic Aspergillus flavus strains from diverse geographical locations in China.
- To investigate the genetic deletions associated with aflatoxin non-production in these strains.
Main Methods:
- Phenotypic and molecular identification of A. flavus strains from peanut fields.
- Ultra-Performance Liquid Chromatography (UPLC) for aflatoxin detection.
- PCR amplification to analyze deletions within the aflatoxin gene cluster.
Main Results:
- 323 A. flavus strains were isolated; 76 were atoxigenic.
- Atoxigenic strain incidence correlated inversely with temperature and directly with latitude.
- 25 distinct deletion patterns were identified in the aflatoxin gene cluster, 22 novel.
- 97% of atoxigenic strains had deletions in key genes: aflT, nor-1, aflR, and hypB.
Conclusions:
- Atoxigenic A. flavus strains with specific gene deletions are prevalent in Chinese peanut fields.
- The identified genes (aflT, nor-1, aflR, hypB) are valuable targets for rapid detection of atoxigenic strains.
- Atoxigenic isolates, particularly those with large deletions, represent promising candidates for biocontrol of aflatoxins.
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