Aflatoxin contamination is one of the important factors that hinders sustainable development of the peanut industry. Precise evaluation of germplasm resources from China and abroad for resistance to A. flavus infection and creation of new resistant germplasms will facilitate the development of resistant cultivars.

The A. flavus infection index of 322 peanut germplasm lines were characterized following in-vitro inoculation of seeds harvested from 3 different “environments” (CA2020, CS2020, CS2021). Aspergillus flavus strain As 3.4408, known for its strong infectivity and high toxin production, was used as the inoculation strain. The botanical type, plant type and nutritional quality of kernels were measured and analyzed. Accessions exhibiting resistance with novel traits were comprehensively evaluated and screened.

Thirteen accessions with stable resistance were identified, accounting for 4.04% of the total germplasm lines evaluated, most of which belonged to var. hypogaea, including two with stable and high resistance (C203 and C206), while no accession was observed to be immune to Aspergillus flavus infection. The frequency distribution of infection index of 322 accessions exhibited continuous variation, with the broad-sense heritability exceeding 0.8, indicating that the A. flavus-resistance of kernels was significantly influenced by genotypes and “environments”, and the phenotypic variation was primarily controlled by genetic factors. Correlation analysis revealed significant positive correlation of infection index of accessions among the different “environments” (P<0.001), and the phenotype of each accession harvested from various “environments” was relatively consistent. Additionally, no significant correlation was found between nutritional quality and infection index. Comparative analysis of infection index among peanut accessions of different botanical and plant types revealed that var. hypogaea/prostrate-type peanuts were more likely to exhibit resistance to A. flavus infection within the existing peanut germplasm resources.

The phenotypes of peanut germplasms harvested from different “environments” in response to A. flavus infection were relatively stable. Variation of kernels resistance to A. flavus infection was primarily controlled by genotype. Accessions C203 and C206, exhibiting stable and high resistance, can serve as excellent resistant parents for the mining of aflatoxin resistance genes and for the improvement of peanut varieties resistant to aflatoxin contamination.