Peanut (Arachis hypogea) accessions differentially accumulate aflatoxins upon challenge by Aspergillus flavus: Implications for aflatoxin mitigation

Abstract

Peanut is among the most important oil crops grown in sub-Saharan Africa for its nutritive value and economic benefit. In this region, Aspergillus flavus infects peanuts and contaminates produce with aflatoxins leading to food insecurity through lowered quality. The impact of aflatoxins transcends the food chain causing harm to human and animal health. The selection and production of aflatoxin-tolerant varieties of peanut is a promising strategy to mitigate their potential harm. We studied the resistance of peanut kernels to aflatoxin accumulation in 25 peanut accessions collected from different growing locations in Kenya, Uganda, and Rwanda based on their unique phenotypic characteristics. To obtain sufficient planting material, the peanut accessions were multiplied separately under standard conditions and harvested at their respective maturity dates then dried and stored at 4 °C before further analysis. At the start of the experiment, the kernels were challenged with a laboratory-characterized toxigenic strain (Aspergillus flavus 1EM1901) and incubated at 28 °C for 7 days. Afterward, the accessions were analysed (ELISA) for aflatoxins. Of the 25 accessions tested, 60 % (n = 15) exhibited kernel resistance to aflatoxin accumulation while 40 % (n = 10) were susceptible (with aflatoxin levels ranging from 0.54 ppb to 1692.92 ppb). Two of the resistant accessions recorded a decrease in aflatoxin accumulation when challenged with toxigenic A. flavus. This differential accumulation of aflatoxins suggests the existence of an inherent trait that can be exploited in breeding programs of peanut varieties with low aflatoxin accumulation when grown in contaminated soils. These findings are further discussed.