Submitted to: Nematology - Abstracts Only
Publication Type: Abstract Only
Publication Acceptance Date: April 2, 2000
Publication Date: N/A
Technical Abstract: Culture filtrates of a strain of Fusarium equiseti isolated from eggs of the soybean cyst nematode inhibit hatching of the root-knot nematode Meloidogyne incognita. In this study, we isolated and identified two compounds with nematode-antagonistic activity from F. equiseti via bioassay-driven fractionation of culture broth. The bioassay consisted of incubating surface-sterilized eggs with DMSO-solubilized fractions and determining the percentages of eggs that hatched and of juveniles that remained mobile. The fractionation process consisted of adsorption of compounds in the broth onto Amberlite XAD-16 resin, partition of the methanol eluate from the XAD-16 between ethyl acetate and 7% methanol in water, chromatography on silica columns with chloroform-methanol mixtures, and high performance liquid chromatography with a gradient of 40-90% acetonitrile in water on a C18 column. Compounds were identified with infrared spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy, electron impact and chemical ionization mass spectrometry, and X-ray crystallography. Two active compounds were discovered to be responsible for the nematode-antagonistic activity: 4,15-diacetoxy-12,13-epoxy-3,7-dihydroxytrichothec-9-en-8-one and 4,15-diacetoxy-12,13-epoxytrichothec-9-en-3-ol (diacetoxyscirpenol). This is the first published report of toxic activity of these two compounds to nematodes.