Mechanism of resistance to pyrazophos in Pyricularia oryzae

Waard, M.A. de; Nistelrooy, J.G.M. van

doi:10.1007/bf01977300

Cited by 6 publications

(4 citation statements)

References 7 publications

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“…The principle of metabolic activation of toxicant pre‐cursors is common knowledge in toxicology (Sultatos, 1994; Takahashi et al , 1999) and is used for designing anti‐tumour drugs (Graham et al , 1991), fungicides (de Waard and van Nistelrooy, 1980) and insecticides (Hedley et al , 1998). We present the first example of substrate‐induced self‐intoxication in nature, in which the expression of the gene that is necessary for self‐intoxication is induced by the non‐toxic precursor.…”

Section: Discussionmentioning

confidence: 99%

Resveratrol acts as a natural profungicide and induces self‐intoxication by a specific laccase

Schouten

Wagemakers

Stefanato

et al. 2002

Molecular Microbiology

157

134

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Summary The grapevine (Vitis) secondary metabolite resveratrol is considered a phytoalexin, which protects the plant from Botrytis cinerea infection. Laccase activity displayed by the fungus is assumed to detoxify resveratrol and to facilitate colonization of grape. We initiated a functional molecular genetic analysis of B. cinerea laccases by characterizing laccase genes and evaluating the phenotype of targeted gene replacement mutants. Two different laccase genes from B. cinerea were characterized, Bclcc1 and Bclcc2. Only Bclcc2 was strongly expressed in liquid cultures in the presence of either resveratrol or tannins. This suggested that Bclcc2, but not Bclcc1, plays an active role in the oxidation of both resveratrol and tannins. Gene replacement mutants in the Bclcc1 and Bclcc2 gene were made to perform a functional analysis. Only Bclcc2 replacement mutants were incapable of converting both resveratrol and tannins. When grown on resveratrol, both the wild type and the Bclcc1 replacement mutant showed inhibited growth, whereas Bclcc2 replacement mutants were unaffected. Thus, contrary to the current theory, BcLCC2 does not detoxify resveratrol but, rather, converts it into compounds that are more toxic for the fungus itself. The Bclcc2 gene was expressed during infection of B. cinerea on a resveratrol‐producing host plant, but Bclcc2 replacement mutants were as virulent as the wild‐type strain on various hosts. The activation of a plant secondary metabolite by a pathogen introduces a new dimension to plant–pathogen interactions and the phytoalexin concept.

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Section: Discussionmentioning

confidence: 99%

Resveratrol acts as a natural profungicide and induces self‐intoxication by a specific laccase

Schouten

Wagemakers

Stefanato

et al. 2002

Molecular Microbiology

157

134

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“…variability, it developed resistance to several fungicides following their intensive applications. Indeed, the resistance of P. oryzae to pyrazophos has been invoked by several authors [26,27]. Sen Gupta and Das [28] have obtained in vitro a stems from H. oryzae resistant to mancozeb.…”

Section: Discussionmentioning

confidence: 99%

Integrated Control against Rice Blast and Leaf Spot by Trichoderma harzianum and Two Fungicides

Mouria¹,

Mouria²,

Hmouni³

et al. 2018

ARRB

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Integrated pest management is performed at intervals of 10 days, during all the season of rice cultivation, by the application of Trichoderma harzianum at a concentration of 10 8 spores/ml, in alternation with the mancozeb at 1000 ppm against rice blast and rice leaf spot and the pyrazophos at 750 ppm against blast. The assessment of symptoms is performed at the beginning of the panicles appearance, by estimating the incidence of the disease and the symptoms severity. Thus, at the end of treatment programs, the alternation of pyrazophos and T. harzianum reduced blast at a rate similar to that noted when pyrazophos is used alone (i.e. respectively 90.5 and 89.1%). This percentage is better than that recorded following treatment by T. harzianum alone (78.4%). Mancozeb alternated with T. harzianum reduced blast at a rate of (83.49%) compared with the fungicide or the antagonist alone (77 and 78.4%). The application of mancozeb alone reduced the leaf spot at a rate similar to that noted following its alternation with T. harzianum (79.2 and 75.64%) and better than that obtained after treatment with T. harzianum alone (69.5%).

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“…Because fungal mycelia appear to lack enzymes causing oxidation to the phosphate analogue or isomerisation to thiolate, wileyonlinelibrary.com/journal/ps wileyonlinelibrary.com/journal/ps direct hydrolysis of the thiophosphate ester to the pyrazolopyrimidinole metabolite is a more plausible bioactivation process. 44 This hypothesis is supported by the fact that the pyrazolopyrimidinole metabolite, in contrast to pyrazophos, also displayed an inhibitory activity towards nucleic acid and protein synthesis and towards oxygen uptake of the agricultural pathogen. 45,46 Therefore, propesticides are affected by the important absorption, distribution, metabolism and excretion (ADME) parameters, 47 which can lead to biological superiority of these modified active ingredients over their non-derivatised analogues.…”

Section: Profungicides With Improved Selectivity On Powdery Mildew DImentioning

confidence: 94%

“…Because fungal mycelia appear to lack enzymes causing oxidation to the phosphate analogue or isomerisation to thiolate, direct hydrolysis of the thiophosphate ester to the pyrazolopyrimidinole metabolite is a more plausible bioactivation process . This hypothesis is supported by the fact that the pyrazolopyrimidinole metabolite, in contrast to pyrazophos, also displayed an inhibitory activity towards nucleic acid and protein synthesis and towards oxygen uptake of the agricultural pathogen …”

Section: The Propesticide Approach In Agrochemistrymentioning

confidence: 99%

Propesticides and their use as agrochemicals

2015

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The synthesis of propesticides is an important concept in design of modern agrochemicals with optimal efficacy, environmental safety, user friendliness and economic variability. Based on increasing knowledge of the biochemistry and genetics of major pest insects, weeds and agricultural pathogens, the search for selectivity has become an ever more important part of pesticide development and can be achieved by appropriate structural modifications of the active ingredient. Propesticides affect the absorption, distribution, metabolism and excretion parameters, which can lead to biological superiority of these modified active ingredients over their non-derivatised analogues. Various selected commercial propesticides testify to the successful utilisation of this concept in the design of agrochemicals. This review describes comprehensively the successful utilisation of propesticides and their role in syntheses of modern agrochemicals, exemplified by selected commercial products coming from different agrochemical areas.

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Mechanism of resistance to pyrazophos in Pyricularia oryzae

Cited by 6 publications

References 7 publications

Resveratrol acts as a natural profungicide and induces self‐intoxication by a specific laccase

Resveratrol acts as a natural profungicide and induces self‐intoxication by a specific laccase

Integrated Control against Rice Blast and Leaf Spot by Trichoderma harzianum and Two Fungicides

Propesticides and their use as agrochemicals

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