Abstract
Mutants ofNectria haematococca var.cucurbitae with high resistance to triadimenol could be isolated at high frequency. Resistance of 30 such mutants studied, was due to a mutation at thetri-1 locus, that maps in linkage group I, 10 cross-over units from the mating type locus. Thetri-1 mutation has no obvious effects on growth and sporulation on media without fungicide and on virulence for squash seedlings and mature fruit. In addition, a resistant mutant killed all of artificially inoculated seedlings in the presence of triadimenol at a concentration which gave 100% protection against the original wild type strain. Thetri-1 mutants were crossresistant at various levels to triadimefon, bitertanol, and propiconazol, but not to non-triazole SBIs. Their sensitivity to three imidazole derivatives was even higher than that of the wild type strains. This is believed to be the first report of a major gene for resistance to an SBI fungicide.
Samenvatting
Isolatie vanNectria haematococca var.cucurbitae mutanten met een hoog niveau van resistentie tegen triadimenol bleek zeer gemakkelijk. Uit genetische analyse van 30 van deze mutanten bleek dat in alle een mutatie voorkwam in de tri-1 locus die kon worden gelokaliseerd op koppelingsgroep I, 10 overkruisingseenheden verwijderd van de ‘mating-type’ locus. Detri-1 mutatie had geen waarneembare effecten op groei en sporulering van de schimmel op fungicide-vrij medium en op pathogeniteit ten aanzien van zaailingen en rijpe vruchten van pompoen.
Triadimenol-behandeling van zaailingen bleek aantasting door de resistente mutant niet te kunnen voorkomen, terwijl behandeling wel effectief bleek tegen de ouderstam.
De triadimenol resistente mutanten vertoonden een verschillend niveau van verminderde gevoeligheid voor triadimefon, bitertanol en propiconazool, maar niet voor niet-triazool SBIs. Detri-1 mutanten vertoonden een verhoogde gevoeligheid voor drie imidazool verbindingen. Het bestaan van een ‘major’ gen voor SBI-resistentie is in dit onderzoek voor het eerst aangetoond.
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References
Bistis, G.N. & Georgopoulos, S.G., 1979. Some aspects of sexual reproduction inNectria haematococca var.cucurbitae. Mycologia 71: 127–143.
Butters, J., Clark, J. & Hollomon, D.W., 1986. Recombination as a means of predicting fungicide resistance in barley powdery mildew. Proceedings 1986 British Crop Protection Conference 2: 561–565.
Deas, A.H.B., Carter, G.A., Clark, T., Clifford, D. & James, C.S., 1986. The enantiomeric composition of triadimenol produced during metabolism of triadimefon by fungi. III. Relationship with sensitivity to triadimefon. Pesticide Biochemistry and Physiology 26: 10–21.
Fuchs, A. & De Waard, M.A., 1982. Resistance to ergosterol biosynthesis inhibitors. I. Chemistry and phenomenological aspects. In: Dekker, J. and Georgopoulos, S.G. (Eds), Fungicide Resistance in Crop Protection. Pudoc, Wageningen, pp. 71–86.
Gasztonyi, M. & Josepovits, G., 1979. The activation of triadimefon and its role in the selectivity of fungicide action. Pesticide Science 10: 57–65.
Georgopoulos, S.G., 1963a. Genetic markers and linkage relationships from tetrad data inHypomyces solani f. sp.cucurbitae. Canadian Journal of Botany 41: 649–659.
Georgopoulos, S.G., 1963b. Pathogenicity of chlorinated-nitrobenzene-tolerant strains ofHypomyces solani f. sp.cucurbitae race I. Phytopathology 53: 1081–1085.
Georgopoulos, S.G., 1987. The development of fungicide resistance. In: Wolfe, M.S. and Caten, C.E. (Eds), Populations of Plant Pathogens; Their Dynamics and Genetics. Blackwell, Oxford, pp. 239–251.
Georgopoulos, S.G. & Skylakakis, G. 1986. Genetic variability in the fungi and the problem of fungicide resistance. Crop Protection 5: 299–305.
Georgopoulos, S.G. & Ziogas, B.N., 1977. A new class of carboxin-resistant mutants ofUstilago maydis. Neth. J. Pl. Path. (Suppl. 1): 235–232.
Hastie, A.C. & Georgopoulos, S.G., 1971. Mutational resistance to fungitoxic benzimidazole derivatives inAspergillus nidulans. J. Gen. Microbiol. 67: 371–373.
Holliday, R., 1961. The genetics ofUstilago maydis. Genetical Research 2: 204–230.
Hollomon, D.W., Butters, J. & Clarck, J., 1984. Genetic control of triadimenol resistance in barley powdery mildew. Proceedings 1984 British Crop Protection Conference 2: 477–482.
Kappas, A. & Georgopoulos, S.G., 1970. Genetic analysis of dodine resistance inNectria haematococca (syn.Hypomyces solani). Genetics 66: 617–622.
Köller, W. & Scheinpflug, H., 1987. Fungal resistance to sterol biosynthesis inhibitors: A new challenge. Plant Disease 71: 1066–1074.
Stanis, V.F. & Jones, A.L., 1985. Reduced sensitivity to sterol-inhibiting fungicides in field isolates ofVenturia inaequalis. Phytopathology 75, 1098–1101.
Toussoun, T.A. & Snyder, W.C., 1961. The pathogenicity, distribution and control of the two races ofFusarium (Hypomyces) solani f. sp.cucurbitae. Phytopathology 51: 17–22.
Van Tuyl, J.M., 1977. Genetics of fungal resistance to systemic fungicides. Mededelingen Landbouwhogeschool, Wageningen 72(2) 1–136.
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Kalamarakis, A.E., Demopoulos, V.P., Ziogas, B.N. et al. A highly mutable major gene for triadimenol resistance in Nectria haematococca var. cucurbitae. Netherlands Journal of Plant Pathology 95 (Suppl 1), 109–120 (1989). https://doi.org/10.1007/BF01974290
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DOI: https://doi.org/10.1007/BF01974290