Detection of Demethylation Inhibitor (DMI) Resistance in<i>Sclerotinia homoeocarpa</i>Populations

Golembiewski, Robert Craig; Vargas, J. M.; Jones, Alan L.; Detweiler, A. R.

doi:10.1094/pd-79-0491

Cited by 103 publications

(78 citation statements)

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“…homoeocarpa are known to exist for traits such as fungicide resistance (Golembiewski et al, 1995;Hsiang et al, 1997), but little is known about pathogenic specialization in this species. Hsiang & Mahuku (1999) found that isolates of S. homoeocarpa from annual bluegrass and creeping bentgrass in Ontario showed genetic differences, but there was no strong clustering of genotypes in UPGMA (unweighted pair group arithmetic average) analysis of RAPD (random amplified polymorphic DNA) and IGS-RFLP (intergenic spacer restriction fragment length polymorphism) data.…”

Section: Introductionmentioning

confidence: 99%

Analyses of RAPD data for detection of host specialization in Sclerotinia homoeocarpa

Hsiang

Yang

et al. 2000

Plant Pathology

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UPGMA analysis, principal component analysis, genetic diversity analysis and genetic distance analysis of RAPD data were used to assess the extent of host specialization in 50 isolates of S. homoeocarpa from five turfgrass hosts. In UPGMA analysis and principal component analysis, the occurrence of host specialization was not readily apparent based on visual inspection. Genetic diversity analysis showed significant differentiation among isolates from different host species (G ST ¼ 0·34, P < 0·001). The strongest evidence for some degree of host specialization came from the statistical analysis of genetic distances among isolates. By grouping pairwise genetic distances between isolates based on their host species, and analysing for average distance within the same host species and among different host species, it was found that the average distance within species was less than among species (P < 0·0001). An analysis of molecular variance of the genetic distances among isolates found that 32·3% of the total variation was attributable to host species. It is concluded that these isolates of S. homoeocarpa showed a weak level of host specialization, which was not readily apparent by UPGMA or principal component analyses, but was revealed by genetic diversity analysis and statistical analysis of genetic distances among isolates. Inoculation tests on different host species and tests using a greater number of isolates are required to confirm the extent of specialization.

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Section: Introductionmentioning

confidence: 99%

Analyses of RAPD data for detection of host specialization in Sclerotinia homoeocarpa

Hsiang

Yang

et al. 2000

Plant Pathology

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“…Many of these fungicides, particularly systemic fungicides, successfully controlled dollar spot when they were first released, but S. homoeocarpa has developed resistance to several classes of fungicides used for dollar spot control in the United States, including earlier heavy metal-based compounds (2,18), traditional contact fungicides (21), and local or acropetal systemic fungicides such as dicarboximides (6), benzimidazoles (6,24,25), and demethylation inhibitors (DMIs) (8,11). More often than not, S. homoeocarpa exhibits crossresistance (i.e., resistance to more than one fungicide within the same chemical group) or multiple resistance (i.e., resistance to different fungicide classes) (23).…”

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Rapid Development of Fungicide Resistance by Sclerotinia homoeocarpa on Turfgrass

Jo¹,

Chang²,

Boehm³

et al. 2008

Phytopathology®

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Dollar spot, caused by Sclerotinia homoeocarpa, is the most prevalent and economically important turfgrass disease in North America. Increasing levels of fungicide resistance, coupled with tightening environmental scrutiny of existing fungicides, has left fewer options for managing dollar spot. More knowledge about S. homoeocarpa populations is needed to improve dollar spot management strategies, especially with respect to minimizing the development of fungicide resistance. Population diversity of S. homoeocarpa was examined using inter-simple sequence repeat markers and vegetative compatibility assays. Two subgroups were found in S. homoeocarpa field populations on both fairway and putting green turfgrass at a research field in Wisconsin. These subgroups were genetically different, vegetatively incompatible, and had different fungicide sensitivities. The frequency of the two genetic subgroups differed significantly between the fairway and putting green, but was uniform within the fairway or within the green. Population dynamics of S. homoeocarpa in response to two systemic fungicides (thiophanate-methyl and propiconazole) were assessed based on in vitro fungicide sensitivity. Dynamics of S. homoeocarpa populations depended on the presence of fungicide-resistant isolates in the initial populations before fungicide applications and changed rapidly after fungicide applications. Shifting of the population toward propiconazole resistance was gradual, whereas thiophanate-methyl resistance developed rapidly in the population. In conclusion, field populations of S. homoeocarpa containing genetically distinct, vegetatively incompatible groups were different on turfgrass that was managed differently, and they were changed rapidly after exposure to fungicides.

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“…Since DMI fungicides represent single-site inhibitors interfering with C-14 demethylation of 24-methylendihydrolanosterol in ergosterol biosynthesis (6,18), a high risk of development of resistance exists (18). In fact, resistance problems have been observed in several pathogens including powdery mildews (10,11,25), Penicillium digitatum (7), Pyrenophora teres (26), Sclerotinia homoeocarpa (9), and Venturia inaequalis (13). Isolates of V. inaequalis with reduced sensitivities to several DMI fungicides have been reported to occur worldwide (4,13,23,24,31,32).…”

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confidence: 99%

Acquisition of Resistance to Sterol Demethylation Inhibitors by Populations of Venturia inaequalis

Kunz¹,

Deising²,

Mendgen³

1997

Phytopathology®

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Kunz, S., Deising, H., and Mendgen, K. 1997. Acquisition of resistance to sterol demethylation inhibitors by populations of Venturia inaequalis. Phytopathology 87:1272-1278.Acquisition of resistance to sterol demethylation inhibitors (DMIs) by populations of Venturia inaequalis was investigated using a microscopical method developed by C. Siebels and K. Mendgen. Microscopical analysis of conidiophore formation enabled the earlier detection of resistance and a clearer distinction between DMI-resistant and DMI-sensitive populations than other in vivo methods commonly used to analyze inhibitory effects of fungicides. In addition, because observations were made on the level of individuals, quantitative measures of the composition of conidial populations were obtained. The development of DMI sensitivity was followed over a period of 3 years in control apple orchards that had never been treated with fungicides and in orchards with DMI history. The 50% effective dose values determined by microscopical evaluation of conidiophore development for untreated populations revealed the baseline sensitivities of 0.3, 0.96, 0.09, 1.22, and 1.92 mg/liter for flusilazole, fenarimol, difenoconazole, tebuconazole, and pyrifenox, respectively. As compared with the baseline sensitivity, all populations with DMI history showed significant resistance to flusilazole. A strong nonlinear correlation (R = 0.96) was found between the resistance factors and the sum of all DMI treatments of the 3 years before taking the sample. According to this correlation, resistance can be expected in all apple orchards of the fruitgrowing area along Lake Constance, Germany, in which more than two DMI treatments per season have been applied. Due to cross-resistance, the recently introduced DMI fungicides difenoconazole, tebuconazole, and pyrifenox did not allow the control of V. inaequalis populations resistant to flusilazole.The success of modern, integrated disease control strategies strongly depends on the availability of efficient curative fungicides (2). Until 1995, sterol demethylation inhibitors (DMIs) were the only curative fungicides registered for use in apple orchards in Germany. Since DMI fungicides represent single-site inhibitors interfering with C-14 demethylation of 24-methylendihydrolanosterol in ergosterol biosynthesis (6,18), a high risk of development of resistance exists (18). In fact, resistance problems have been observed in several pathogens including powdery mildews (10,11,25), Penicillium digitatum (7), Pyrenophora teres (26), Sclerotinia homoeocarpa (9), and Venturia inaequalis (13). Isolates of V. inaequalis with reduced sensitivities to several DMI fungicides have been reported to occur worldwide (4,13,23,24,31,32). Resistance to DMI fungicides is under multigenic control, increasing gradually by additive action of the different resistance genes (6,15). Depending on the stringency of the selection pressure, sensitivity of V. inaequalis populations may, therefore, shift gradually from baseline sensitivity to a distinct le...

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Detection of Demethylation Inhibitor (DMI) Resistance inSclerotinia homoeocarpaPopulations

Cited by 103 publications

References 0 publications

Analyses of RAPD data for detection of host specialization in Sclerotinia homoeocarpa

Analyses of RAPD data for detection of host specialization in Sclerotinia homoeocarpa

Rapid Development of Fungicide Resistance by Sclerotinia homoeocarpa on Turfgrass

Acquisition of Resistance to Sterol Demethylation Inhibitors by Populations of Venturia inaequalis

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