Similarities in the antifungal activities of fenpiclonil, iprodione and tolclofos‐methyl against Botrytis cinerea and Fusarium nivale

Abstract

Fenpiclonil [4-(2,3-dichlorophenyl)pyrrole-3-carbonitrile], a new agricultural fungicide, is a structural analogue of the antibiotic pyrrolnitrin used as an antimycotic in animals. Its spectrum of antifungal activity is similar to that of iprodione and tolclofos-methyl, which are representatives of dicarboximide and aromatic hydrocarbon fungicides. Laboratory mutants of Botryris cinerea and Fusarium nivale were simultaneously resistant to fenpiclonil, iprodione and tolclofos-methyl and they showed an increased susceptibility to high osmotic pressure (sodium chloride, glucose). Strains of B. cinerea, collected in Champagne vineyards, which were resistant to dicarboximides were not resistant to fenpiclonil and tolclofos-methyl. The antioxidant a-tocopheryl acetate, and the cytochrome P-450 inhibitors piperonyl butoxide and tebuconazole antagonized the fungitoxicity of fenpiclonil and iprodione in a wild-type strain of B. cinerea. The uncoupling activity of fenpiclonil, iprodione and tolclofos-methyl was detected in mitochondria from both a wild-type strain and a laboratory mutant of B. cinerea.The concentrations effective towards this process were greater than those inhibiting the mycelial growth of wild-type strains. These results suggest that fenpiclonil, iprodione, tolclofos-methyl and related fungicides have the same biochemical mode of action. However, a primary effect on respiration, previously considered for pyrrolnitrin, seems to be improbable.

Effects of Iprodione and Fludioxonil on Glycerol Synthesis and Hyphal Development inCandida albicans

“…It is known that the antifungal activity of dicarboximides and phenylpyrroles in B. cinerea is reduced by a mixed function oxidase inhibitor, piperonyl butoxide, and radical scavenger, a-tocopherol acetate. 20,27) A similar phenomenon was observed with the wild-type strain of N. crassa (unpublished result). The growth inhibition of iprodione and ‰udioxonil on the IFO1385 strain was almost completely eliminated by piperonyl butoxide, and partially by a-tocopherol acetate (Fig.…”

“…1) and fenpiclonil, 26) has commonly been observed, speciˆcally in laboratory dicarboximideresistant strains. 27) Such resistant mutants often show abnormal osmotic sensitivity. In N. crassa, osmoticsensitive mutants, nik1 W os-1, os-2, os-4, and os-5, are resistant to dicarboximides and phenylpyrroles.…”

The effects of cold-hardening and Microdochium nivale infection on oxidative stress and antioxidative protection of the two contrasting genotypes of winter triticale

“…Variable levels of M. nivale infection in triticale were reported from field experiments and from testing at control 1 3 conditions [3][4][5], but no fully resistant genotype was found. The fungicides used so far against M. nivale are very harmful to the environment and not sufficiently effective [6][7][8]. Only cold-hardening is regularly reported to induce increased resistance against pink snow mould [4,5,[9][10][11][12][13][14], but its effect is genotype-dependent.…”

Putative Homologs ofSSK22MAPKK Kinase andPBS2MAPK Kinase ofSaccharomyces cerevisiaeEncoded byos-4andos-5Genes for Osmotic Sensitivity and Fungicide…

“…[7][8][9] Both fungicides are used to control Botrytis cinerea, which is pathogenic to vegetables, vines, and ‰ow-ers. 10,11) The treatment of wild-type strains of N. crassa with iprodione and ‰udioxonil causes the swelling of the germ tubes and accumulation of intracellular glycerol. 12) In contrast, fungicides do not cause the os mutants to accumulate glycerol.…”