Submitted to: British Mycological Society Annual International Symposia Series
Publication Type: Abstract Only
Publication Acceptance Date: April 22, 2001
Publication Date: N/A
Technical Abstract: Fungi isolated from soybean cyst nematode (Heterodera glycines) eggs were tested for production of compounds that affected in vitro egg hatch and juvenile (J2) mobility of H. glycines and root-knot nematode (Meloidogyne incognita). To conduct the assays, ca. 250 fungus isolates were cultured individually in potato dextrose broth (PDB), and the culture broths were centrifuged and filtered to remove biomass. Nematode eggs were placed in the sterile-filtered broths and in PDB controls. Hatch of H. glycines eggs in the filtrates ranged from 15% to 224% of hatch in the PDB controls. Hatch of M. incognita eggs was 2% to 121% of hatch in the PDB controls. Fewer then 5% of the isolates produced compounds that substantially inhibited J2 mobility. Two fungi that suppressed egg hatch, Fusarium equiseti and Chaetomium globosum, were selected for identification of the compounds active against root-knot nematode. The compounds from F. equiseti were determined to be the trichothecenes 4,15- diacetylnivalenol and diacetoxyscirpenol. Trichothecene compounds are mycotoxins active against a number of organisms. The active agent from C. globosum was identified as flavipin, a compound that previously has been isolated from fungi. The effect of flavipin solutions on root-knot nematode colonization of Cucumis melo plants was tested in greenhouse studies at 30, 60, and 120 microgram/ml. No effects were detected on gall formation after two weeks or on subsequent nematode egg and J2 populations after 55 days.