Mycoflora and Fumonisin Mycotoxins Associated with Cowpea [Vigna unguiculata (L.) Walp] Seeds

Abstract

Cowpea seed samples from South Africa and Benin were analyzed for seed mycoflora. Fusarium species detected were F. equiseti, F. chlamydosporum, F. graminearum, F. proliferatum, F. sambucinum, F. semitectum, and F. subglutinans. Cowpea seed from South Africa and Benin and F. proliferatum isolates from Benin, inoculated onto maize patty medium, were analyzed for fumonisin production. Samples were extracted with methanol/water and cleaned up on strong anion exchange solid phase extraction cartridges. HPLC with precolumn derivatization using o-phthaldialdehyde was used for the detection and quantification of fumonisins. Cowpea cultivars from South Africa showed the presence of fumonisin B1 at concentrations ranging between 0.12 and 0.61 μg/g, whereas those from Benin showed no fumonisins. This is believed to be the first report of the natural occurrence of FB1 on cowpea seed. Fumonisin B1, B2, and B3 were produced by all F. proliferatum isolates. Total fumonisin concentrations were between 0.8 and 25.30 μg/g, and the highest level of FB1 detected was 16.86 μg/g.