Frequency of mutations associated with fungicide resistance and population structure of Mycosphaerella graminicola in Tunisia
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The occurrence of fungicide resistance in Mycosphaerella graminicola populations from Tunisia was investigated by examining mutations known to be associated with strobilurin and azole resistance. Few mutations associated with fungicide resistance were detected. No evidence for strobilurin resistance was found among 357 Tunisian isolates and only two among 80 sequenced isolates carried mutations associated with azole resistance. A network analysis suggested that these mutations emerged independently from mutations found in previously described European populations. The population genetic structure of M. graminicola in Tunisia was analyzed using variation at 11 microsatellite loci. Populations in Tunisia were characterized by high gene and genotype diversity. All populations were in gametic equilibrium and mating type proportions did not deviate from the 1:1 ratio expected under random mating, consistent with regular cycles of sexual reproduction. In combination with a high degree of gene flow among sampling sites, M. graminicola must be considered a pathogens with high evolutionary potential. Thus, control strategies against Septoria blotch in Tunisia should be optimized to reduce the emergence and spread of resistant isolates.
KeywordsDMI fungicides Gene flow QoI fungicides Parallel evolution Septoria tritici
We thank Marcello Zala, Stefano Torriani, Megan McDonald and Joanna Bernardes de Assis for technical support and helpful discussions. The Genetic Diversity Center of ETH Zurich provided facilities for collecting molecular data. This project was supported by the Swiss government through the Federal Commission for Scholarships for Foreign Students (FCS; RefNr: 20080384) who sponsored SB.
- Cools, H. J., Parker, J. E., Kelly, D. E., Lucas, J. A., Fraaije, B. A., & Kelly, S. L. (2010). Heterologous expression of mutated eburicol 14α-demethylase (CYP51) proteins of Mycosphaerella graminicola to assess effects on azole fungicide sensitivity and intrinsic protein function. Applied and Environmental Microbiology, 76, 2866–2872.PubMedCrossRefGoogle Scholar
- El Chartouni, L., Tisserant, B., Siah, A., Duyme, F., Leducq, J. B., Deweer, C., Fichter-Roisin, C., Sanssené, J., Durand, R., Halama, P., & Reignault, P. (2011). Genetic diversity and population structure in French populations of Mycosphaerella graminicola. Mycologia, 103, 764–774.PubMedCrossRefGoogle Scholar
- Fraaije, B. A., Cools, H. J., Kim, S. H., Motteram, J., Clark, W. S., & Lucas, J. A. (2007). A novel substitution I381V in the sterol 14-demethylase (CYP51) of Mycosphaerella graminicola is differentially selected by azole fungicides. Molecular Plant Pathology, 8, 245–254.PubMedCrossRefGoogle Scholar
- Goodwin, S. B., Van Der Lee, T., Cavaletto, J. R., Hekkert, B., Crane, C. F., & Kema, G. H. J. (2007). Identification and genetic mapping of highly polymorphic microsatellite loci from an EST database of the septoria tritici blotch pathogen Mycosphaerella graminicola. Fungal Genetics and Biology, 44, 398–414.PubMedCrossRefGoogle Scholar
- Goudet, J. (2001) FSTAT, a program to estimate and test gene diversities and fixation indices (version 2.9.3) (Retrieved August 2009, from Lausanne University, Population Genetics Laboratory: http://wwwunilch/izea/softwares/fstathtml).
- Kema, G. H. J., Annone, J. G., Sayoud, R., Van Silfhout, C. H., Van Ginkel, M., & de Bree, J. (1996). Genetic variation for virulence and resistance in the wheat-Mycosphaerella graminicola pathosystem. I. Interactions between pathogen isolates and host cultivars. Phytopathology, 86, 200–212.CrossRefGoogle Scholar
- Leroux, P., Gredt, M., Walker, A. S., Moinard, J. M., & Caron, D. (2005). Resistance of the wheat leaf blotch pathogen Septoria tritici to fungicides in France. In H. W. Dehne, U. Gisi, K. H. Kuck, P. E. Russell, & H. Lyr (Eds.), Modern fungicides and antifungal compounds, IV (pp. 115–124). Alton: BCPC.Google Scholar
- Oerke, E. C., Dehne, H. W., Schonbeck, F., & Weber, A. (1994). Crop Production and Crop Protection: Estimated Losses in Major Food and Cash Crops (p. 808). Amsterdam: Elsevier Science.Google Scholar
- Peakall, R., & Smouse, P. (2005) GenALEx 6: Genetic analysis in excel population genetic software for teaching and research. (Retrieved August 2009, from Australian National University, Research School of Biology: http://wwwanueduau/BoZo/GenAlEx/).
- Raymond, M., & Rousset, F. (1995). GENEPOP (version 1.2): population genetics software for exact tests and ecumenicism. Journal of Heredity, 86, 248–249.Google Scholar
- Stammler, G., Kern, L., Semar, M., Glaettli, A., & Schoefl, U. (2008). Sensitivity of Mycosphaerella graminicola to DMI fungicides related to mutations in the target gene cyp51 (14α-demethylase). In H. W. Dehne, H. B. Deising, U. Gisi, K. H. Kuck, P. E. Russel, & H. Lyr (Eds.), Modern fungicides and antifungal compounds, V (pp. 137–142). Braunschweig: DPG-Verlag.Google Scholar
- Zhan, J., Pettway, R. E., & McDonald, B. A. (2003). The global genetic structure of the wheat pathogen Mycosphaerella graminicola is characterized by high nuclear diversity, low mitochondrial diversity, regular recombination, and gene flow. Fungal Genetics and Biology, 8, 286–297.CrossRefGoogle Scholar