Abstract:
Aflatoxin B
1(AFB
1) is a highly toxic secondary metabolite produced by
Aspergillus flavus, which endangers food security and human health. To investigate the effect of the transcription factor AFLA_105170 on
A. flavus, this study successfully constructed a gene deletion strain of AFLA_105170 using a homologous recombination strategy. First, the effect of AFLA_105170 gene deletion on the growth phenotype and sclerotia formation of
A. flavus was determined. The effect of the AFLA_105170 gene deletion on AFB
1 biosynthesis was examined using thin-layer chromatography(TLC) and high-performance liquid chromatography(HPLC). The effect of AFLA_105170 gene deletion on the expression levels of genes involved in AFB
1 synthesis was further detected by fluorescence quantitative PCR(RT-PCR). The cell wall and membrane integrity of the AFLA_105170 mutant were examined by stress response and staining assay. Finally, the effect of AFLA_105170 gene deletion on the pathogenicity of strains was investigated using peanut and maize as media. The results showed that deletion of the AFLA_105170 gene significantly inhibited the growth, spore production, sclerotia production of
Aspergillus flavus, and severely inhibited the biosynthesis of AFB
1. It was found that the content of AFB
1 in the AFLA_105170 gene deletion strain decreased by 69.81% and 64.56% in PDB and PDA medium, respectively, and the genes
aflJ,
aflW,
aflS, and
aflM related to AFB
1 synthesis were significantly down-regulated. Moreover, the integrity of cell membrane and cell wall in the AFLA_105170 gene deletion strain were disrupted, and its pathogenicity in peanut and maize was reduced. These results suggest that the deletion of AFLA_105170 inhibits
A. flavus growth by damaging the integrity of the cell wall and membrane, and affects the synthesis of AFB
1 by suppressing the expression levels of AFB
1 synthesis genes. This study provides a scientific basis for effective prevention and control of
A. flavus and aflatoxin.