Affiliation:
1. Department of Biological Sciences, Northern Illinois University, DeKalb, Ilinois, USA
2. Food and Feed Safety Research Unit, USDA/ARS, Southern Regional Research Center, New Orleans, Louisiana, USA
Abstract
ABSTRACT
The opportunistic plant-pathogenic fungus
Aspergillus flavus
produces carcinogenic mycotoxins termed aflatoxins (AF). Aflatoxin contamination of agriculturally important crops, such as maize, peanut, sorghum, and tree nuts, is responsible for serious adverse health and economic impacts worldwide. In order to identify possible genetic targets to reduce AF contamination, we have characterized the
artA
gene, encoding a putative 14-3-3 homolog in
A. flavus
. The
artA
deletion mutant presents a slight decrease in vegetative growth and alterations in morphological development and secondary metabolism. Specifically,
artA
affects conidiation, and this effect is influenced by the type of substrate and culture condition. In addition, normal levels of
artA
are required for sclerotial development. Importantly,
artA
negatively regulates AF production as well as the concomitant expression of genes in the AF gene cluster. An increase in AF is also observed in seeds infected with the
A. flavus
strain lacking
artA
. Furthermore, the expression of other secondary metabolite genes is also
artA
dependent, including genes in the cyclopiazonic acid (CPA) and ustiloxin gene clusters, in this agriculturally important fungus.
IMPORTANCE
In the current study,
artA
, which encodes a 14-3-3 homolog, was characterized in the agriculturally and medically important fungus
Aspergillus flavus
, specifically, its possible role governing sporulation, formation of resistant structures, and secondary metabolism. The highly conserved
artA
is necessary for normal fungal morphogenesis in an environment-dependent manner, affecting the balance between production of conidiophores and the formation of resistant structures that are necessary for the dissemination and survival of this opportunistic pathogen. This study reports a 14-3-3 protein affecting secondary metabolism in filamentous fungi. Importantly,
artA
regulates the biosynthesis of the potent carcinogenic compound aflatoxin B1 (AFB1) as well as the production of other secondary metabolites.
Funder
U.S. Department of Agriculture
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
8 articles.
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