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Title: FUSARIUM SPECIES FROM NEPALESE RICE AND THE PRODUCTION OF MYCOTOXINS AND GIBBERELLIC ACID BY SELECTED SPECIES

Author
item Desjardins, Anne
item MANANDHAR, H - NEPAL AGR RES CNCL, NEPAL
item Plattner, Ronald
item MANANDHAR, G - NEPAL AGR RES CNCL, NEPAL
item Poling, Stephen
item Maragos, Chris

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: To assess the safety of rice being used for human consumption in Nepal, we surveyed 48 rice samples for fusarium fungi and for several mycotoxins. We found that Nepalese rice is infected with a number of Fusarium species that produce mycotoxins, but that the rice samples contain low, acceptable levels of these mycotoxins. These results indicate that low-technology harvest and storage practices of a traditional farming system can control mycotoxins and make agricultural products safe for human and animal consumption.

Technical Abstract: Samples of rice seeds with husks were collected in 1997 from farms in the foothills of the Nepal Himalaya. The predominant Fusarium species in surface-disinfected seeds were those of the Gibberella fujikuroi complex, including mating population A (anamorph F. moniliforme), mating population C (anamorph F. fujikuroi), and mating population D (anamorph F. proliferatum). Other predominant species were G. zeae (anamorph F. graminearum) and F. semitectum, with F. acuminatum, F. anguioides, F. avenaceum, F. chlamydosporum, F. equiseti, and F. oxysporum occasionally present. Mating tests and chemical analyses demonstrated that the morphologically similar mating populations C and D were reproductively isolated and produced different metabolite profiles. Although both species produced moniliformin and beauvericin, mating population C produced high levels of gibberellins and little or no fumonisins, whereas most strains of mating population D produced fumonisins, but none produced gibberellins. Despite the occurrence of fumonisin-producing strains of mating population D, and of nivalenol-producing and deoxynivalenol-producing strains of G. zeae, Nepalese rice showed no detectable contamination with these mycotoxins. The widespread occurrence of mating population D in rice also suggests some role for this species in producing the complex symptoms of bakanae disease.