The 14-3-3 Protein Homolog ArtA Regulates Development and Secondary Metabolism in the Opportunistic Plant Pathogen Aspergillus flavus

The opportunistic plant-pathogenic fungusAspergillus 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 theartA gene, encoding a putative 14-3-3 homolog inA. flavus . TheartA 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 ofartA 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 theA. flavus strain lackingartA . Furthermore, the expression of other secondary metabolite genes is alsoartA 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 fungusAspergillus flavus , specifically, its possible role governing sporulation, formation of resistant structures, and secondary metabolism. The highly conservedartA 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.