Publication Date

2018

Document Type

Dissertation/Thesis

First Advisor

Calvo, Ana M.

Degree Name

Ph.D. (Doctor of Philosophy)

Legacy Department

Department of Biological Sciences

Abstract

Aspergillus flavus is an opportunistic fungal plant and human pathogen and producer of mycotoxins including aflatoxin B1 (AFB1). As part of our ongoing studies to elucidate biological functions of the A. flavus rtfA gene, we examined its role in pathogenicity of both plant and animal model systems. rtfA encodes a putative RNA-Pol II transcription elongation factor, previously characterized in Saccharomycese cerevisiae, Aspergillus nidulans, Aspergillus fumigatus, where it was shown to regulate several important cellular processes, including morphogenesis, secondary metabolism. In addition, an initial study in A. flavus indicated that rtfA also influences development and production of AFB1, however its effect on virulence is unknown. The current study revealed that the rtfA gene is indispensable for normal pathogenicity in plants when using peanut seed as infection model, and in animals, as shown in the Galleria mellonella infection model. Interestingly, rtfA positively regulates several processes known to be necessary for successful fungal invasion and colonization of host tissue, such as adhesion to surfaces; protease and lipase activity; cell wall composition and integrity; and resistance to oxidative stress. In addition, metabolomic analysis revealed that A. flavus rtfA affects the production of several secondary metabolites including AFB1, aflatrem, paxilline, leporins, aflavinines, ditryptophenaline, and aspirochlorine, supporting a role of rtfA as a global regulator of secondary metabolism. Heterologous complementation of an A. flavus deletion rtfA strain with rtfA homologs from A. nidulans or S. cerevisiae did fully rescue wild type phenotype, indicating that these rtfA homologs are functionally conserved between these three species.

Extent

66 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

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