rtfA, a putative RNA-Pol II transcription elongation factor gene, is necessary for normal morphological and chemical development in Aspergillus flavus

• Published in: Applied microbiology and biotechnology 2016-06, Vol.100 (11), p.5029-5041
• Main Authors: Lohmar, Jessica M., Harris-Coward, Pamela Y., Cary, Jeffrey W., Dhingra, Sourabh, Calvo, Ana M.
• Format: Article
• Language: English
• Subjects: Aflatoxin B1 - metabolism; Aflatoxins; Applied Genetics and Molecular Biotechnology; Asexuality; Aspergillus; Aspergillus flavus; Aspergillus flavus - genetics; Aspergillus flavus - metabolism; Aspergillus nidulans; Biomedical and Life Sciences; Biosynthesis; Biotechnology; Carcinogens; DNA methylation; Fungal Proteins - genetics; Fungal Proteins - metabolism; Fungi; Gene Deletion; Gene expression; Gene Expression Regulation, Fungal; Genes; Genes, Fungal; Genetic aspects; Life Sciences; Metabolism; Metabolites; Microbial Genetics and Genomics; Microbiology; Morphogenesis; Morphology; Mycotoxins; Observations; Pathogens; Peptide Elongation Factors - genetics; Peptide Elongation Factors - metabolism; Physiological aspects; Proteins; RNA Polymerase II - genetics; RNA Polymerase II - metabolism; Saccharomyces cerevisiae; Secondary Metabolism; Secondary metabolites; Spores, Fungal - metabolism; Studies; Transcription factors; Yeast
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-016-7418-7

The filamentous fungus Aspergillus flavus is an agriculturally important opportunistic plant pathogen that produces potent carcinogenic compounds called aflatoxins. We identified the A. flavus rtfA gene, the ortholog of rtf1 in Saccharomyces cerevisiae and rtfA in Aspergillus nidulans . Interestingly, rtfA has multiple cellular roles in this mycotoxin-producing fungus. In this study, we show that rtfA regulates conidiation. The rtfA deletion mutant presented smaller conidiophores with significantly reduced conidial production compared to the wild-type strain. The absence of rtfA also resulted in a significant decrease or lack of sclerotial production under conditions that allowed abundant production of these resistance structures in the wild type. Importantly, the deletion of rtfA notably reduced the production of aflatoxin B 1 , indicating that rtfA is a regulator of mycotoxin biosynthesis in A. flavus . In addition, the deletion rtfA also altered the production of several unknown secondary metabolites indicating a broader regulatory scope. Furthermore, our study revealed that rtfA controls the expression of the global regulators veA and laeA , which further influence morphogenesis and secondary metabolism in A. flavus .