EFFECT OF MELANIN BIOSYNTHESIS INHIBITING COMPOUNDS ON GAEUMANNOMYCESSPECIES

Inhibition of melanin production was observed in Gaeumannomyces isolat es treated with DHN-melanin inhibiting compounds (tricyclazole, pyroqu ilon, fthalide and chlobenthiazone) but not with DOPA-melanin inhibiti ng compounds (tropolone, kojic acid, 2-mercaptobenzimidazole and dieth yldithiocarbamate). This indicates that the melanin associated with ce ll walls of G. graminis and G. incrustans is DHN-melanin. Depending on the compound, consistent inhibition of melanin was observed at levels that were not inhibitory to fungal growth. In vitro pathogenicity to wheat by these isolates was not affected by the DHN-melanin compounds.