Submitted to: Journal of Chemical Ecology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/12/2001
Publication Date: 5/1/2001
Citation: Nitao, J.K., Meyer, S.L., Schmidt, W.F., Fettinger, J.C., Chitwood, D.J. 2001. Nematode-antagonistic trichothecenes from fusarium equiseti. Journal of Chemical Ecology 27(5): 859-869. Interpretive Summary: Plant-parasitic nematodes are small worms that feed on the roots of plants, often weakening or stunting the plants by stealing nutrients and damaging the roots. Crop losses from nematodes total billions of dollars annually in the U.S. Some commonly used nematicides are now known to pose unacceptable risks to the environment and to human health, and their use is being scaled back. Nematode control will become increasingly difficult unless new approaches are found to replace these older methods. One approach being explored is the use of microbes, such as fungi and bacteria. In addition to directly attacking nematodes, microbes can produce natural chemicals that affect nematode physiology and behavior. Our earlier work indicated that a strain of the fungus Fusarium equiseti produces chemicals that inhibit the egg hatch and juvenile mobility of the root-knot nematode, an important pest. To determine the feasibility of these chemicals as agents to control nematodes, we isolated and identified the chemicals responsible for the anti-nematode action. Two trichothecene compounds were identified. Trichothecenes are toxic to a wide range of organisms, making them poor candidates as a means to control nematodes. The results are significant because identifying how microbes affect plant-feeding nematodes is necessary for improving the effectiveness and safety of new control techniques using microbes; accordingly, the results will be used by scientists developing such techniques.
Technical Abstract: A strain of the fungus Fusarium equiseti isolated from soybean cyst nematode secretes nematode-antagonistic compounds. Bioassay-guided fractionation of an extract of the culture broth was undertaken to identify the compounds. Fractions were assayed for activity against a root-knot nematode (Meloidogyne incognita), a pest that attacks the roots of numerous plant species. Two trichothecene compounds were isolated that inhibited egg hatch and immobilized second-stage juveniles of the root-knot nematode: 4,15-diacetoxy-12,13-epoxy-3, 7-dihydroxytrichothec-9-en-8-one (4,15-diacetylnivalenol) and 4, 15-diacetoxy-12,13-epoxy-trichothec-9-en-3-ol (diacetoxyscirpenol). This is the first published report of these compounds affecting plant-parasitic nematodes.