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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Foodborne Toxin Detection and Prevention Research » Research » Publications at this Location » Publication #355117
Research Project: Biocontrol Interventions for High-Value Agricultural Commodities

Location: Foodborne Toxin Detection and Prevention Research

Title: Biocontrol strain Aspergillus flavus WRRL 1519 has differences in chromosomal organization and an increased number of transposon-like elements compared to other strains

Author
item PENNERMAN, KAYLA - Rutgers University
item GONZALEZ, JOHANNY - Rutgers University
item CHENOWETH, LYDIA - Rutgers University
item BENNETT, JOAN - Rutgers University
item YIN, GUOHUA - Rutgers University
item Hua, Sui Sheng

Submitted to: Molecular Genetics and Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2018
Publication Date: 8/10/2018
Publication URL: http://handle.nal.usda.gov/10113/6206862
Citation: Pennerman, K.K., Gonzalez, J., Chenoweth, L.F., Bennett, J.W., Yin, G., Hua, S.T. 2018. Biocontrol strain Aspergillus flavus WRRL 1519 has differences in chromosomal organization and an increased number of transposon-like elements compared to other strains. Molecular Genetics and Genomics. 293(6):1507-1522. https://doi.org/10.1007/s00438-018-1474-x.
DOI: https://doi.org/10.1007/s00438-018-1474-x

Interpretive Summary: Retrotransposons are demonstrated to be near gene regulators, virulence genes, and biosynthetic gene clusters. We have demonstrated that chromosomal variation and genome-wide associations with extrachromosomal mismatches may be associated with repetitive sequences of retrotransposons within 10,000 bp to any gene cluster in biocontrol strain WRRL1519. Bioinfromatic analysis indicates the fungal strain exhibits a noticeably different genome organization in comparison to other strains of A. flavus. Published literatures suggest the frequencies of three types of transposable elements (TEs) are consistently greater in non-afatoxigenic A. oryzae than in afltoxigenic A. flavus, implying that TEs may present a method by which some non-afltoxigenic strains may arise. Future experimentation and continued bioinformatics analyses will potentially reveal whether transposon activity in A. flavus can lead to natural occurrences of non-aflatoxigenic strains.

Technical Abstract: Aflatoxins are toxic secondary metabolites produced by members of the genus Aspergillus, most notably A. flavus. Non-aflatoxigenic strains of A. flavus are commonly used for biocontrol of the aflatoxigenic strains to reduce aflatoxins in corn, cotton, peanuts and tree nuts. However, genomic differences between aflatoxigenic strains and non-aflatoxigenic strains have not been reported in detail, though such differences may further elucidate the evolutionary histories of certain biocontrol strains and help guide development of other useful strains. We recently reported the genome and transcriptome sequencing of A. flavus WRRL 1519, a strain isolated from almond that does not produce aflatoxins or cyclopianzonic acid due to deletions in the biosynthetic gene clusters. The genome assembly of strain WRRL1519 was improved by anchoring 84 of the 127 scaffolds to the putative nuclear chromosomes of strain NRRL 3357. A predicted Chromosomal map of WRRL1519 was established. The five largest areas of extra-chromosomal mismatches observed between WRRL 1519 and NRRL 3357 were not similar to any of the mismatches were observed with pair-wise comparisons of NRRL 3357 to other nonaflatoxigenic strains NRRL 21882, NRRL 30797 or NRRL 18543. Additionally, there was a marked overrepresentation of repetitive sequences in WRRL 1519 compared to other inspected A. flavus strains. This is the first report of detection of a large number of putative retrotransposons in any A. flavus strain.