Cerato-ulmin and a glycopeptide purified from Ophiostoma ulmi culture filtrates have been characterized as toxins involved in the Dutch Elm Disease (DED). On the other hand, use of fungal toxins and culture filtrates to screen in vitro for resistance, has been successful for several species. Therefore, in order to test their potential as in vitro selective agents against DED, Ophiostoma ulmi toxins were added to elm tissue culture medium. The results were compared to fungal filtrates, high molecular dextran, or Tween 80 effects. It was attempted to establish a relation to clone susceptibility. Three replicates of 24 calli were used and their fresh and dry weight were recorded after 3 weeks. Fungal filtrates inhibited fresh weight (up to 37%) and dry weight formation (up to 28%). However, no clear correlation with clonal susceptibility was found. When cerato-ulmin was added to the medium a growth stimulation (16% F.W.) was observed and Tween 80 induced a similar effect. The glycopeptide and its related crude toxin lowered the fresh weight for all clones (12%). When dextran (M.W. 7x10 hoch 4) was added to the culture medium the weight changed in the same way suggesting a non specific action of the toxin. In spite of this observation, and although its inhibition was quite different from filtrates, the glycopeptide seems to be a better candidate for selective pressure than cerato-ulmin.
181.4 (Reaktion auf und Widerstandsfähigkeit gegen biotische Einflüsse, Feuer und Verunreinigungen der Umwelt [siehe vorzugsweise die Untertitel von 4]) 172.8 (Eumycetes (Echte Pilze)) 971 (Kongresse, Konferenzen; Exkursionen)
