Regulation of Morphology, Aflatoxin Production, and Virulence of Aspergillus flavus by the Major Nitrogen Regulatory Gene areA

Abstract

<i>Aspergillus flavus</i> is a renowned plant, animal and human pathogen. <i>areA</i> is a global nitrogen regulatory gene of the GATA transcription factor family, shown to be the major nitrogen regulator. In this study, we identified <i>areA</i> in <i>A. flavus</i> and studied its function. The AreA protein contained a signatory zinc finger domain, which is extremely conserved across fungal species. Gene deletion (Δ<i>areA</i>) and over-expression (OE::<i>areA</i>) strains were constructed by homologous recombination to elucidate the role of <i>areA</i> in <i>A. flavus</i>. The Δ<i>areA</i> strain was unable to efficiently utilize secondary nitrogen sources for growth of <i>A. flavus</i>, and it had poorly developed conidiophores, when observed on complete medium, resulting in the production of significantly less conidia than the wild-type strain (WT). Aflatoxin B1 (AFB1) production was reduced in Δ<i>areA</i> compared with the WT strain in most conditions tested, and Δ<i>areA</i> had impaired virulence in peanut seeds. <i>areA</i> also played important roles in the sensitivity of <i>A. flavus</i> to osmotic, cell wall and oxidative stresses. Hence, <i>areA</i> was found to be important for the growth, aflatoxin production and pathogenicity of <i>A. flavus</i>. This work sheds light on the function of <i>areA</i> in the regulation of the nitrogen metabolism of <i>A. flavus,</i> and consequently aims at providing new ways for controlling the crossover pathogen, <i>A. flavus</i>.