Metabolism of O-Ethyl S, S-Diphenyl Phosphorodithioate (Hinosan)by Mycelial Cells of Pyricularia oryzae

Uesugi, Yasuhiko; Tomizawa, Chōjirō

doi:10.1271/bbb1961.35.941

Cited by 19 publications

(2 citation statements)

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“…Inability to break down EBP or edifenphos would enhance their fungitoxicity because metabolites of these fungicides are not fungitoxic (Uesugi and Tomizawa, 1971 ;Tomizawa and Uesugi, 1972). This does not hold since no negative crossresistance with pyrazophos was found.…”

Section: Discussionmentioning

confidence: 99%

Mechanism of resistance to pyrazophos in Pyricularia oryzae

Waard

Nistelrooy

1980

Netherlands Journal of Plant Pathology

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Pyrazophos-resistant strains of Pyricularia oryzae were isolated from sectors in colonies of the fungus on a pyrazophos-containing agar medium. In contrast to the wild-type strain, resistant strains did not metabolize pyrazophos (Afugan, Curamil) into its phosphate analogue and 2-hydroxy-5-methyl-6-ethoxycarbonylpyrazolo(l,5-a)pyrimidine (PP), which is regarded as the fungitoxic principle of pyrazophos. Resistant strains possessed a slightly increased sensitivity to PP. These data indicate that the mechanism of resistance to pyrazophos is not related to a change of the target sites of PP, but rather with inability to convert pyrazophos into PP. The pyrazophos-resistant strains displayed cross-resistance to the organophosphorus fungicides EBP (Kitazin) and edifenphos (Hinosan). The mechanism of cross-resistance involved is not understood.

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Section: Discussionmentioning

confidence: 99%

Mechanism of resistance to pyrazophos in Pyricularia oryzae

Waard

Nistelrooy

1980

Netherlands Journal of Plant Pathology

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“…Fungicides used were mainly IBP and BPA because Of their comparatively high solubility in water. Mycelia (1.5 g fresh weight) were incubated in fungicide Solution (10 ml) containing 1% glucose and 1/30 M phosphate buffer (pH 7.0) as described previously (Uesugi and Tomizawa, 1971).…”

Section: Methodsmentioning

confidence: 99%

Back-mutation of an organophosphorus thiolate-resistant mutant of Pyricularia oryzae

Uesugi

Katagiri

1977

Neth. J. Pl. Path.

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From a large number of conidia of a mutant of Pyricularia oryzae resistant to organophosphorus thiolate (PTL) fungicides (mutant I), a new mutant was selected on agar plates containing a phosphoramidate (PA). The latter compound was found to be more fungicidal to mutant I than to the wild-type strain. The PA-resistant mutant obtained by this selection (mutant II) was as sensitive as the wild-type strain to PTL fungicides. A synergistic joint action of PTL and PA, as shown against the wild-type strain but not against mutant I, was also shown against mutant II. The wild-type strain and mutant I and II were compared regarding their metabolism of PTL and PA compounds. Marked differences were hardly found among the three strains when they were incubated with low dosages of either PTL or PA. At higher dosages of either PTL or PA which affected the three strains differentially, the wild-type strain as well as mutant II metabolized PTL and PA far more rapidly than mutant I did. Therefore, in the present experiments mutant II was similar to the wild-type strain with regard to sensitivity to PTL and PA and to their joint action, and with respect to ability to metabolize these compounds.

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Mutual antagonism between sterol demethylation inhibitors and phosphorothiolate fungicides on Pyricularia oryzae and the implications for their mode of action

et al. 1993

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Joint action between a phosphorothiolate (PTL) fungicide, iprobenfos, and a sterol demethylation inhibitor (DMI), pefurazoate, was tested by crossed paper technique on three types of field isolates of Pyricularia oryzae Cavara that differed in PTL sensitivity and metabolism. Mutual antagonism in anti‐fungal action between iprobenfos and pefurazoate was observed in a wild‐type field isolate of the fungus sensitive to PTL and in an isolate moderately resistant to PTL, but not in a PTL‐resistant isolate lacking the ability to metabolize PTL. Antagonism of the antifungal action of iprobenfos by pefurazoate seemed to be a result of inhibition of activation by cleavage of the P‐S bond of iprobenfos mediated by mixed‐function oxygenase (mfo) activity, while antagonism of the anti‐fungal action of pefurazoate by iprobenfos may be caused by the binding of pefurazoate by large amounts of an iprobenfos‐induced mfo which results in reduced inhibition of ergosterol biosynthesis. In the PTL‐resistant isolate, the mutually antagonistic action was not observed, presumably because the induction of the mfo‐metabolizing iprobenfos was lacking. Similar antagonism was also observed when another PTL, edifenphos, was used instead of iprobenfos, and when other DMIs, propiconazole, prochloraz and hexaconazole were used instead of pefurazoate. The results of the present experiment indicate that DMIs may also bind to and inhibit an inducible type of fungal mfo which metabolizes xenobiotics, and that PTLs may be activated by an mfo prior to their anti‐fungal action.

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Metabolism of O-Ethyl S, S-Diphenyl Phosphorodithioate (Hinosan)by Mycelial Cells of Pyricularia oryzae

Cited by 19 publications

References 0 publications

Mechanism of resistance to pyrazophos in Pyricularia oryzae

Mechanism of resistance to pyrazophos in Pyricularia oryzae

Back-mutation of an organophosphorus thiolate-resistant mutant of Pyricularia oryzae

Mutual antagonism between sterol demethylation inhibitors and phosphorothiolate fungicides on Pyricularia oryzae and the implications for their mode of action

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