Mycotoxins and toxigenic species incidence in oilseed rape

During an investigation of the mycoflora on oilseed rape, the predominant fungal species present in 118 samples collected in Spain were Penicillium spp., Alternaria alternata (Fries) Keissler and Aspergillus flavus. None of the 20 samples analysed having an infection rate of Alternaria higher than 65% presented contamination by Alternaria mycotoxins. Only aflatoxin B1 was detected in one of the 15 samples analysed with an infection rate of Aspergillus flavus higher than 65%. Alternaria alternata strains were cultured on rice and on whole and ground oilseed rape to compare their mycotoxin production. All the assayed strains produced tenuazonic acid (40 to 30 000 mg kg−1) and altertoxin I (in traces) on all media studied. Alternariol methyl ether, alternariol and altertoxin II was also produced by all strains on rice, but alternariol only was produced by two strains on ground oilseed rape. None of these three toxins were produced on whole oilseed rape. Out of 591 Aspergillus flavus isolates from oilseed rape, only 12 revealed aflatoxigenic capacity.