Inhibition of ergosterol biosynthesis in Ustilago maydis by the fungicide 1-[2-(2, 4-dichlorophenyl)-4-ethyl-1, 3-dioxolan-2-ylmethyl]-1H-1, 2, 4-triazole |
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Authors: | Matthew J Henry Hugh D Sisler |
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Abstract: | Inhibition of sporidial multiplication in cultures of Ustilago maydis by 1-2-(2, 4-dichlorophenyl)-4-ethyl-1, 3-dioxolan-2-ylmethyl]-1H-1, 2, 4-triazolea (CGA-64251), at concentrations of 0.1, 1.0 and 5.0 μg ml?1, increased from about 15% during the first 4 h, to 58–70% during the subsequent 4 to 12-h period. Sporidia became swollen and highly branched in the presence of the fungicide. Total lipid content as a percentage of the dry weight was not affected after exposure of the sporidia to the fungicide at 0.1 or 5 μg ml?1 for 4 h, but synthesis of ergosterol and other demethyl-sterols was inhibited by 87–92%. Large quantities of methyl-sterol precursors of ergosterol and of free fatty acids accumulated in the treated sporidia. Fungitoxicity of CGA-64251 is attributed to inhibition of ergosterol biosynthesis at the stage of sterol C-14 demethylation. |
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