BIOCHEMICAL EFFECTS OF THE PHENYLPYRROLE FUNGICIDE FENPICLONIL IN FUSARIUM-SULPHUREUM (SCHLECHT)

Fenpiclonil (CGA 142705) is the first commercially developed phenylpyrrole fungicide based on chemical modifications of the antibiotic pyrrolnitrin. The fungicide is toxic to representatives of Ascomycetes, Basidiomycetes, and Deuteromycetes. In this report, we described the effect of fenpiclonil on several physiological processes using the target fungus Fusarium sulphureum as a sensitive test organism. EC50 of fenpiclonil for radial growth on PDA and mycelial growth in liquid medium was 0.5 and 10 ·M, respectively. At a low inhibitory concentration, fenpiclonil did not immediately affect oxygen consumption, nuclear division, and DNA, RNA, protein, chitin, ergosterol, and (phospho)lipid biosynthesis. However, the accumulation of amino acids and sugars was instantaneously affected at concentrations ranging from 4.2 to 42 ·M. The reduction in accumulation was accompanied by an increased accumulation of the membrane potential probe tetraphenylphosphonium bromide and a marginal change of the proton gradient probe propionic acid. These results suggest that the biochemical mechanism of action of fenpiclonil may be related to membrane-dependent transport processes. To our knowledge, such a mechanism has not been described before for any fungicide. © 1993 by Academic Press, Inc.