Genome sequence and comparative analyses of atoxigenic Aspergillus flavus WRRL 1519

Authors: YIN, GUOHUA - Rutgers University; Hua, Sui Sheng; PENNERMAN, KAYLA - Rutgers University; Yu, Jiujiang; BU, LIJING - University Of New Mexico; SAYRE, RICHARD - New Mexico Consortium; BENNETT, JOAN - Rutgers University

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2018
Publication Date: 4/24/2018
Citation: Yin, G., Hua, S.T., Pennerman, K.K., Yu, J., Bu, L., Sayre, R.T., Bennett, J. 2018. Genome sequence and comparative analyses of atoxigenic Aspergillus flavus WRRL 1519. Mycologia. 110(3):482-493. https://doi.org/10.1080/00275514.2018.1468201.
DOI: https://doi.org/10.1080/00275514.2018.1468201

Interpretive Summary: Computational analyses of the genomic and transcriptomic data of A. flavus strain WRRL 1519 indicates that the strain may be a good addition to the suite of aflatoxin and CPA biocontrol agents. The strain has large deletions of key toxin synthesis genes, which are unlikely to revert. Additionally, we have shown that from genomic data, we can readily observe genetic differences among strains and tie to differences to predictions about the toxicity and pathogenicity. Nineteen of the unique non-homologous proteins of WRRL1519 were annotated with Gene Ontology (GO) terms, which indicated importance in transcription, membranes and nucleic acid binding functions. These results will help guide future experimental investigations to elucidate the genetic bases for differences between effective and poor atoxigenic biocontrol agents. Further analyses of the A. flavus genomes will be useful for identification of defense, metabolic and competive genes of atoxigenic A. flavus strains that promote biocontrol-related management of toxin contamination.

Technical Abstract: Aflatoxins are fungal secondary metabolites that often contaminate foodstuffs and crops, the major producer of which is Aspergillus flavus. Use of non-aflatoxigenic strains of A. flavus to compete against aflatoxin-producing strains has emerged as one of the best management practices for reducing aflatoxins contamination, yielding successful commercial products. The genome and transcriptome of atoxigenic A. flavus strain WRRL1519 were sequenced to define the genetic characteristics of the strain in relation to other A. flavus strains. WRRL1519 was similar to other strains in size (38.0 Mb), GC content (47.2%), number of predicted secondary metabolite gene clusters (56) and number of putative proteins (12,121). About 87.4% of the predicted proteome had shared identity with protein sequences derived from other A. flavus genomes. Compared to aflatoxigenic A. flavus strains, strain WRRL1519 had low shared identity or deletions for many genes and proteins required for aflatoxins and cyclopiazonic acid (CPA) synthesis. Over half of the aflatoxin synthesis gene cluster was missing, while the CPA gene cluster could not be identified.