Screening of higher fungi for the production of nematicidal compounds using Meloidogyne incognita (Kofoid and White) chitwood as test organism
1996
Mayer, A. | Anke, H. | Sterner, O. (Kaiserslautern Univ. (Germany). Lehrbereich Biotechnology)
Three test systems for the detection of nematicidal compounds in cultures of higher fungi were established. All tests were carried out with axenic larvae of the plant pathogen Meloidogyne incognita. The water agar assay was used to detect antagonistic activities of nematophagous fungi as well as the production of nematicidal compounds in solid surface cultures. In the migration assay, extracts from submerged cultures and fungal metabolites were tested for toxic activity and the activity to interfere with the migration of the larvae to the root tips. In the microtiter plate assay nematicidal activities of extracts and pure compounds were detected. This assay was also used for the bioactivity-guided isolation of the active compounds. From submerged cultures of an ascomycetes, 5-pentyl-2-furaldehyde, a secondary metabolite already known from the basidiomycetes Irpex lacteus, was isolated. From the mycelia of Omphalotus olearius, a cyclic peptide with high nematicidal activity was obtained. Both metabolites showed higher activity towards M. incognita than towards Caenorhabditis elegans. Most compounds which were isolated using C. elegans as test organisms were not active towards M. incognita. This clearly demonstrates that in the screening for new natural nematicides with a potential for application in agriculture plant pathogens have to be used
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