Identification and Characterization of Peanut Seed Coat Secondary Metabolites Inhibiting Aspergillus flavus Growth and Reducing Aflatoxin Contamination

The peanut seed coat acts as a physical and biochemical
barrier
against Aspergillus flavus infection;
however, the nature of the inhibitory chemicals in the peanut seed
coat in general is not known. This study identified and characterized
peanut seed coat metabolites that inhibit A. flavus growth and aflatoxin contamination. Selected peanut accessions grown
under well-watered and water-deficit conditions were assayed for A. flavus resistance, and seed coats were metabolically
profiled using liquid chromatography mass spectrometry. Kyoto Encyclopedia
of Genes and Genome phenylpropanoid pathway reference analysis resulted
in the identification of several seed coat metabolic compounds, and
ten selected metabolites were tested for inhibition of A. flavus growth and aflatoxin contamination. Radial
growth bioassay demonstrated that 2,5-dihydroxybenzaldehyde inhibited A. flavus growth (98.7%) and reduced the aflatoxin
contamination estimate from 994 to 1 μg/kg. Scanning electron
micrographs showed distorted hyphae and conidiophores in cultures
of 2,5-dihydroxybenzaldehyde-treated A. flavus, indicating its potential use for field application as well as seed
coat metabolic engineering.