TITLE Mycoflora and mycotoxins in dry bean (Phaseolus vulgaris) produced in Taiwan and in Ontario, Canada
AUTHOR T. C. Tseng
Institute of Botany, Academia Sinica, Taipei, Taiwan, Republic of China
J. C. Tu
Agriculture and Agri-Food Canada Research station, Harrow, Ontario, NOR IGO, Canada
S. S. Tzean
Department of Plant Pathology and Entomology, National Taiwan University, Taipei, Taiwan, Republic of China
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ABSTRACT We undertook a comparative investigation of mycoflora and mycotoxins in dry bean (Phaseolus vulgaris) produced in Taiwan and Ontario. Seedborne fungi were isolated and characterized. A profile of bean mycoflora was developed for each region having distinct climatic conditions. The frequency of various isolated fungi was also determined. The average percentages of seedborne fungi in the bean lots from Ontario and Taiwan were 54.8 and 58.5%, respectively. The fungi most-frequently isolated from the diseased Ontario beans were Alternaria (61.1%), Fusarium (18.0%), Rhizoctonia (6.1%), Penicillium (5.2%), Rhizopus (3.2%), Sclerotinia (3.0%), Gliocladium (2.2%), and Mucor (1.7%). The fungi most-frequently isolated from the diseased Taiwan beans were Aspergillus (48.5%), Penicillium (27.6%), Eurotium (6.7%), Rhizopus (5.3%) and Curvularia (2.4%). Based on these profiles, Fusarium and Aspergillus were identified as the most-probable mycotoxin-producing fungi in the bean lots from Ontario and Taiwan, respectively. Subsequent analyses were made of the fungal-infected and non-infected beans from each region. The infected beans from Ontario contained the fusarium toxins diacetoxyscripenol, deoxynivalenol, T-2 toxin and fumonisin B1, but no aflatoxins. The infected beans from Taiwan contained aflatoxins B1, B2, G1, and G2, but no fusarium toxins. In the non-infected bean samples from both regions, however, neither fusarium toxins nor aflatoxins were detected. The monitoring of mycotoxins in imported beans can be simplified by developing a profile of the mycoflora from each exporting country. The profile can help to narrow the range of mycotoxins to be detected. A similar approach can be taken for other field crops.
KEYWORD Mycoflora; Mycotoxins; Phaseolus vulgaris; Seedborne fungi;
ARTICLE INFO Botanical Bulletin of Academia Sinica, Volume 36 Number 4 October 1995, page 229-234, 6 pages
PUBLISHER Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China