Induction of Fungal Resistance to Metalaxyl by Ultraviolet Irradiation

Bruin, G. C. A.

doi:10.1094/phyto-72-476

Cited by 36 publications

(10 citation statements)

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“…The sexually derived spores of oomycetes are frequently recalcitrant to germination and, for outcrossing species such as P. infestans, conversion to homozygosity requires the identification of rare lines derived from the self-fertilization of heterozygous mutants. The mutagenesis of oomycetes to drug insensitivity has frequently led to a loss or disruption of one or more life cycle stages, pathogenicity or nutritional impairment (Bruin and Edgington, 1982;Castro et al, 1970;Long and Keen, 1977). Here, mutants to MPD were able to form all asexual stages, and were pathogenic on potato.…”

Section: Discussionmentioning

confidence: 99%

Mandipropamid targets the cellulose synthase‐like PiCesA3 to inhibit cell wall biosynthesis in the oomycete plant pathogen, Phytophthora infestans

Blum

Boehler

Randall³

et al. 2010

Molecular Plant Pathology

120

113

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Oomycete plant pathogens cause a wide variety of economically and environmentally important plant diseases. Mandipropamid (MPD) is a carboxylic acid amide (CAA) effective against downy mildews, such as Plasmopara viticola on grapes and potato late blight caused by Phytophthora infestans. Historically, the identification of the mode of action of oomycete-specific control agents has been problematic. Here, we describe how a combination of biochemical and genetic techniques has been utilized to identify the molecular target of MPD in P. infestans. Phytophthora infestans germinating cysts treated with MPD produced swelling symptoms typical of cell wall synthesis inhibitors, and these effects were reversible after washing with H(2)O. Uptake studies with (14)C-labelled MPD showed that this oomycete control agent acts on the cell wall and does not enter the cell. Furthermore, (14)C glucose incorporation into cellulose was perturbed in the presence of MPD which, taken together, suggests that the inhibition of cellulose synthesis is the primary effect of MPD. Laboratory mutants, insensitive to MPD, were raised by ethyl methane sulphonate (EMS) mutagenesis, and gene sequence analysis of cellulose synthase genes in these mutants revealed two point mutations in the PiCesA3 gene, known to be involved in cellulose synthesis. Both mutations in the PiCesA3 gene result in a change to the same amino acid (glycine-1105) in the protein. The transformation and expression of a mutated PiCesA3 allele was carried out in a sensitive wild-type isolate to demonstrate that the mutations in PiCesA3 were responsible for the MPD insensitivity phenotype.

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Section: Discussionmentioning

confidence: 99%

Mandipropamid targets the cellulose synthase‐like PiCesA3 to inhibit cell wall biosynthesis in the oomycete plant pathogen, Phytophthora infestans

Blum

Boehler

Randall³

et al. 2010

Molecular Plant Pathology

120

113

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“…After 6 transfers of different resistant isolates on medium with or without the fungicide, the resistant isolate 200R, reverted back to sensitivity to metalaxyl. Such instability with metalaxyl-resistant isolates has also been observed by BRUIN and EDGINGTON (1981) in P. ultimum, JOSEPH and COFFEY (1984 in Phytophthora capsid, and COFFEY et al (1984) in Phytophthora dtricola. According to their hypothesis, resistant isolates require a period of time to stabilize and the variation in the behaviour of the isolates may reflect different pathways along which the resistant isolates evolve.…”

Section: Discussionmentioning

confidence: 63%

“…Resistance to systemic fungicides is a frequently reported and welldocumented phenomemon (BRUIN and EDGINGTON 1981, DEKKER 1976, JOSEPH and COFFEY 1984. Metalaxyl, (N-(2,6-dimethylphenyl)-N-(methoxyacetyl) alanine methyl ester, Ridomil 25 % WP), is an effective fungicide with specific activity against pathogens belonging to the Peronosporales (URECH et al 1977).…”

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confidence: 99%

“…and development of resistance has been investigated in vitro and in vivo with isolates of P. parasitica Dastur and P. dtrophthora Smith and Smith) Leonian (FARIH et al 1981), P. parasitica var. nicotianae (STAUB and YOUNG 1980), P. dnnamomi Rands and P. dtricola Sawada (COFFEY et al 1984, JOSEPH and, and P. capsid Leonian (BRUIN andEDGINGTON 1981,1982). Metalaxyl at low concentration was highly inhibitory to mycelial growth, sporangia production and zoospore germination of P. cactorum (Lebert & Cohn) Schroter (ELLIS et al 1982).…”

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confidence: 99%

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In vitro Selection of Strains of Phytophthora cactorum Resistant to Metalaxyl

Utkhede¹,

Gupta²

1988

Journal of Phytopathology

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Isolates of Phytophthora cactorum resistant to the systemic fungicide metalaxyl were obtained by exposing them to sequentially increased concentrations of metalaxyl. A linear relationship was observed between the concentrations of metalaxyl and percentage inhibition of mycelial growth of P. cactorum. The stability of metalaxyl‐resistant isolates 150R and 250R was confirmed after six serial transfers on corn meal agar without fungicide. The in vitro metalaxyl‐resistant isolate (Ph10) was less aggressive on apple rootstocks compared with the Ph07 isolated from metalaxyl‐treated trees and the Ph03 isolated from untreated trees. Metalaxyl‐resistant and sensitive isolates remained sensitive to the chemically unrelated fungicide fosetyl‐Al at high concentration (600 μg/ml), to mancozeb, and to a mixture of metalaxyl + mancozeb. Significant differences in resistance to metalaxyl existed among P. cactorum field isolates.

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“…Conflicting reports, regarding the genetic link between fitness characteristics and resistance to phenylamides or to QoI fungicides in oomycetes were also found in the literature. Data supporting a significant reduction of fitness characteristics (Bruin and Edgington, 1982), or indicating stability of the resistant phenotype (Joseph and Coffey, 1984;Chabane et al, 1993) and/or pathogenicity of mutant isolates similar to the sensitive ones (Bruin and Edgington, 1982;Kadish et al, 1990;Chabane et al, 1993) have been reported. However, resistance to phenylamides was found to be under the control of a single gene in P. infestans, and correlation studies between resistance and fitness components did not reveal any association (Lee et al, 1999).…”

Section: Discussionmentioning

confidence: 99%

A High Multi-drug Resistance to Chemically Unrelated Oomycete Fungicides in Phytophthora infestans

et al. 2006

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Mutants of Phytophthora infestans with high resistance to the amidocarbamates iprovalicarb and benthiavalicarb and to the cyanoimidazole cyazofamid were isolated after UV-mutagenesis and selection on media containing one of the above fungicides. In vitro fungitoxicity tests showed that all resistant strains presented a highly reduced sensitivity to both cyazofamid and to the amidocarbamates. Cross-resistance studies with other oomycete fungicides from different chemical groups showed that the mutation(s) for resistance to iprovalicarb (IPV), benthiavalicarb (BVC) and cyazofamid (CZF) also greatly reduced the sensitivity of mutant strains to the phenylamide metalaxyl, acetamide cymoxanil, morpholine dimethomorph, benzamide zoxamide and to chlorothalonil. A lower reduction of sensitivity of mutant strains to the strobilurins azoxystrobin, kresoxim-methyl, pyraclostrobin and trifloxystrobin, azolones famoxadone and fenamidone and to antimycin A was observed. A resistance correlation was not apparent for the dithiocarbamate propineb and phenylpyridinamine fluazinam. Studies of fitness parameters in the wild-type and mutant strains of P. infestans showed that most resistant isolates had significantly reduced sporulation and sporangial germination, but not in the differentiation of sporangia into zoospores. Pathogenicity tests on tomato seedlings showed that most resistant isolates were significantly less pathogenic compared to the wild-type parent strain. However, experiments on the stability of the resistant phenotypes did not show a reduction in resistance when the mutants were grown for more than eleven generations on inhibitor-free medium. This is believed to be the first report of high level multi-drug resistance in fungal pathogens to chemically unrelated fungicides inhibiting different sites of cellular pathway.

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Induction of Fungal Resistance to Metalaxyl by Ultraviolet Irradiation

Cited by 36 publications

References 0 publications

Mandipropamid targets the cellulose synthase‐like PiCesA3 to inhibit cell wall biosynthesis in the oomycete plant pathogen, Phytophthora infestans

Mandipropamid targets the cellulose synthase‐like PiCesA3 to inhibit cell wall biosynthesis in the oomycete plant pathogen, Phytophthora infestans

In vitro Selection of Strains of Phytophthora cactorum Resistant to Metalaxyl

A High Multi-drug Resistance to Chemically Unrelated Oomycete Fungicides in Phytophthora infestans

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