Bioassay of the contamination of lupin seed by the mycotoxin phomopsin

Abstract

Samples of seed from commercial crops of Lupinus spp. in three States were tested for the presence of phomopsin, the causative agent of lupinosis. Each of 43 samples was tested in one of two laboratories using a nursling rat bioassay, and 12 of these were tested in both. Factors that could affect reproducibility of the assay were examined. There was good agreement in assessments of toxicity between laboratories. The efficiency of extraction was found to vary from about 15% at low concentrations of phomopsin to no more than 60%. Phomopsin was detected in 17 of the 43 samples, at levels ranging from < 6 µg/kg to 360 µg/kg. Phomopsis leptostromiformis infection was detected in 25 of 31 samples of seed from Western Australia, the highest infection level being 18%. The highest levels of phomopsin were found in samples with more than 8% infection.