Fenpropimorph: A three site inhibitor of ergosterol biosynthesis in Nectria haematococca var. cucurbitae

• Published in: Pesticide biochemistry and physiology Vol. 39; no. 1; pp. 74 - 83
• Main Authors: Ziogas, B.N., Oesterhelt, G., Masner, P., Steel, C.C., Furter, R.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 1991; Elsevier
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; BIOSINTESIS; BIOSYNTHESE; BIOSYNTHESIS; Chemical control; Control; ENZYME INHIBITORS; EPOXIDE HYDROLASE; ERGOSTEROL; FENPROPIDIN; FONGICIDE; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; FUNGICIDAS; FUNGICIDES; HIDROLASAS; HYDROLASE; HYDROLASES; INHIBIDORES DE ENZIMAS; INHIBITEUR D'ENZYME; ISOMERASAS; ISOMERASE; ISOMERASES; MODE OF ACTION; NECTRIA; OXIDOREDUCTASES; OXIDORREDUCTASAS; OXYDOREDUCTASE; Phytopathology. Animal pests. Plant and forest protection; PYRIFENOX; SQUALENE; TEBUCONAZOLE; TOXICIDAD; TOXICITE; TOXICITY; TRIADIMENOL; TRIDEMORF; TRIDEMORPH; TRITERPENOIDE; TRITERPENOIDOS; TRITERPENOIDS; Ergosterol; Squalene monooxygenase (2,3-epoxidizing); Enzyme inhibitor; Biosynthesis; Sterol synthesis inhibitor; Phytopathogen; Synthetic inhibitor; Morpholine derivatives; Fungicide; Site of action; Pyridine derivatives; Fungi; Nectria haematococca; Piperidine derivatives; Triazole derivatives; Ascomycetes; Mechanism of action; Isomerase; Thallophyta; Reductase; Sterol
• ISSN: 0048-3575; 1095-9939
• DOI: 10.1016/0048-3575(91)90215-8

The effect of fenpropimorph, fenpropidin, tridemorph, pyrifenox, triadimenol, and tebuconazole on growth and sterol synthesis of a wild-type strain of Nectria haematococca var. cucurbitae was studied. Fenpropimorph-treated mycelia showed a dose dependent drop in ergosterol content with a parallel accumulation of Δ 8-sterols, Δ 14-sterols, and squalene, indicative of inhibition of three different enzymes in the sterol biosynthetic pathway: Δ 8-Δ 7-isomerase, Δ 14-reductase, and squalene epoxidase. Untreated mycelia incorporated [ 14C]acetate into 4-desmethyl sterols, composed primarily of ergosterol, whereas in fenpropimorph-treated mycelia the label accumulated in squalene and a reduction of C-4 desmethyl sterols was observed. Fenpropidin was found to be a potent inhibitor of Δ 8-Δ 7-isomerase and Δ 14-reductase, while tridemorph specifically inhibited Δ 8-Δ 7-isomerase. Triadimenol, pyrifenox, and tebuconazole inhibited the C-14 demethylation step, which resulted in a decrease in ergosterol and an increase in C-14 methyl sterols.