殺菌剤ブチオベートの作用機構

加藤 寿郎

doi:10.1584/jpestics.7.427

Buthiobate is effective in controlling powdery mildews of agricultural and ornamental crops. Microscopic observations indicated that the fungicide caused abnormal swelling of germ tubes of Sphaerotheca fuliginea and excessive branching of hyphae in Monilinia fructigena without inhibition of spore germination. Respiratory activity and the incorporations of radioactive substrates into proteins, nucleic acids and cell wall were not significantly inhibited in M. fructigena during early incubation periods with the fungicide. On the contrary, sterol biosynthesis was severely affected by the treatment. By gas-liquid chromatographic analyses, it was shown that an amount of ergosterol decreased in the treated culture with a concomitant accumulation of 24-methylenedihydrolanosterol and obtusifoliol. In cell-free homogenates of Saccharomyces cerevisiae, the conversion of acetate-U-¹⁴C to 4-desmethyl sterols was also proved to be suppressed by the fungicide and radioactivity accumulated in the fraction of lanosterol. ¹⁴C-Labelled lanosterol was not converted to 4-desmethyl sterols in the presence of the fungicide, whereas the conversion of ¹⁴C-labelled 14-desmethyl-lanosterol was not inhibited. The results therefore indicate selective inhibition of demethylation at C-14 in the biosynthetic processes of ergosterol. The fungicide tridemorph was also found to be an inhibitor of ergosterol biosynthesis in Botrytis cinerea. Since fecosterol, ergosta-8, 22, 24(28)-trien-3β-ol and ergosta-8, 22-dien-3β-ol accumulated in the treated culture, the fungicide seemed to block the conversion of fecosterol to episterol, i. e. the Δ⁸→Δ⁷ isomerization.

殺菌剤ブチオベートの作用機構

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収録刊行物

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殺菌剤ブチオベートの作用機構

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説明

収録刊行物

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