Observation on Baseline Sensitivity of Erysiphe necator Genetic Groups to Azoxystrobin


Powdery mildew, caused by Erysiph necator, is a common and severe fungal disease of grapevine all over the world. The disease costs millions of dollars to vine growers, due to intensive use of fungicides and yield losses. Recently in population of E. necator two genetic groups have been described, the two groups seem to occupy different temporal niches, with a temporal alternation that is clear-cut in vineyards intensively treated with chemical fungicides. QoI-STAR (Quinol Outside Inhibitors-Strobilurin Type of Action and Resistance) fungicides are widely used to control the disease, and generally carry a high risk of pathogen resistance development. To clarify the behaviors of the biotrophic fungus when treated with azoxystrobin as a representative of QoI-STAR, baseline sensitivity of laboratory isolates were determined. A leaf bioassay and the primers RSCBF1 and RSCBR2 designed on the highly conserved regions of cytb gene in fungi were used. Partial sequence of E. necator cytb gene were obtained. Attempts to obtain a laboratory mutant were not totally successful. The sensitivity to azoxystrobin (EC50) in isolates of genetic group B was significantly higher than in isolates of group A, to which all the isolates collected later in the season belonged. The higher sensitivity to azoxystrobin fungicides observed in group B isolates can be at the basis of their precocious disappearance in vineyards, and can have important implications for powdery mildew control strategies.

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H. Hajjeh, "Observation on Baseline Sensitivity of Erysiphe necator Genetic Groups to Azoxystrobin," American Journal of Plant Sciences, Vol. 3 No. 11, 2012, pp. 1640-1645. doi: 10.4236/ajps.2012.311199.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] M. Miazzi, H. Hajjeh and F. Faretra, “Occurrence and Distribution of Two Distinct Genetic Group in Population of Erysiphe necator Schw. In Southern Italy,” Journal of Plant Pathology, Vol. 90, No. 3, 2008, pp. 563-573.
[2] M. Miazzi and H. R. Hajjeh, “Differential Sensitivity to Triadimenol of Erysiphe necator Isolates Belonging to Different Genetic Groups,” Journal of Plant Pathology, Vol. 93, No. 3, 2011, pp. 729-735.
[3] S. P. Heaney, A. A. Hall, S. A. Davies and G. Olaya, “Resistance to Fungicides in the Qo1-STAR Cross-Resistance Group: Current Perspectives,” Proceedings of Brighton Crop Protection Conference-Pests and Diseases, Vol. 2, 2000, pp. 755-762.
[4] H. Ishii, “QoI Fungicide Resistance: Current Status and the Problems Associated with DNA-Based Monitoring,” In: U. Gisi, I. Chet and M. L. Gullino, Eds., Recent Developments in Management of Plant Diseases, Plant Pathology in the 21st Century, Springer, Dordnecht, 2009, pp. 37-45.
[5] D. Zheng, G. Olaya and W. Koller, “Characterization of Laboratory Mutants of Venturia inaequalis Resistant to Strobilurins-Related Fungicides Kresoxim-Methyl,” Current Genetics, Vol. 38, 2000, pp. 148-155. doi:10.1007/s002940000147
[6] S. Baumler, H. Sierotzki, U. Gisi, V. Mohler, F.G. Felsenstein and G. Schwarz, “Evaluation of Erysiphe graminis f. sp. tritici Field Isolates for Resistance to Strobilurin Fungicides with Different SNP Detection Systems,” Pest Management Science, Vol. 59, No. 3, 2003, pp. 310-314. doi:10.1002/ps.639
[7] P. M. Wood and D. W. Hollomon, “A Critical Evaluation of the Role of Alternative Oxidase in the Performance of Strobilurin and Related Fungicides Acting at the Qo Site of Complex III,” Pest Management Science, Vol. 59, No. 5, 2003, pp. 499-511. doi:10.1002/ps.655
[8] H. Sierotzki, R. Frey, J. Wullschleger, S. Palermo, S. Karli, J. Godwin and U. Gisi, “Cytochrome b Gene Sequence and Structure of Pyrenophora teres and P. triticirepentis and Implications for QoI Resistance,” Pest Management Science, Vol. 63, No. 3, 2007, pp. 225-233. doi:10.1002/ps.1330
[9] M. Miguez, C. Reeve, P. M. Wood and D. W. Hollomon, “Alternative Oxidase Reduces the Sensitivity of Mycosphaerella graminicola to QoI Fungicides,” Pest Management Science, Vol. 60, No. 1, 2004, pp. 3-7. doi:10.1002/ps.837
[10] D. Fernández-Ortu?o, J. A. Torés, A. de Vicente and A. Pérez-García, “The QoI Fungicides, the Rise and Fall of a Successful Class of Agricultural Fungicides,” In: O. Carisse, Ed., Fungicides, Janeza Trdine, Rijeka, 2010, pp. 203-220. doi:10.5772/13205
[11] FRAC, “International FRAC QoI Working Group Minutes 2011, All Crops,” Fungicide Resistance Action Committee, 2011.
[12] P. Hoffmann, I. Fuzi and F. Viranyi, “Indirect Effect of Fungicide Treatments on Chasmothecia of Erysiphe necator Schwein Overwintering on Grapevine Bark,” Plant Protection Science, Vol. 48, No. 1, 2012, pp. 21-30.
[13] J. F. Colcol, “Fungicide Sensitivity of Erysiphe necator and Plasmopara viticola from Virginia and Nearby States,” M.Sc. Thesis, Virginia Polytechnic Institute and State University, Blacksburg, 2008.
[14] A. Baudoin, G. Olaya, F. Delmotte, J. F. Colcol, and H. Sierotzki, “QoI Resistance of Plasmopara viticola and Erysiphe necator in the mid-Atlantic United States,” 2008. http://www.plantmanagementnetwork.org/pub/php/research/2008/qoi/
[15] M. Miazzi, P. Natale, S. Pollastro and F. Faretra, “Handling of the Biotrophic Pathogen Uncinula necator (Schw.) Burr. under Laboratory Conditions and Observations on Its Mating System,” Journal of Plant Pathology, Vol. 78, 1997, pp. 71-77.
[16] H. Ishii, B. A. Fraaije, T. Sugiyama, K. Noguchi, K. Nishimura, T. Takeda, T. Amano and D. W. Hollomon, “Occurrence and Molecular Characterization of Strobilurin Resistance in Cucumber Powdery Mildew and Downy Mildew,” Phytopathology, Vol. 91, No. 12, 2001, pp. 1166-1171. doi:10.1094/PHYTO.2001.91.12.1166
[17] A. Rügner, J. Rumbolz, B. Huber, G. Bleyer, U. Gisi, H. Kassemeyer and R. Guggenheim, “Formation of Overwintering Structures of Uncinula necator and Colonisation of Grapevine under Field Conditions,” Plant Pathology, Vol. 51, No. 3, 2002, pp. 322-330. doi:10.1046/j.1365-3059.2002.00694.x
[18] J. Rumbolz and W. D. Gubler, “Susceptibility of Grapevine Buds to Infection by Powdery Mildew Erysiphe necator,” Plant Pathology, Vol. 54, No. 4, 2005, pp. 535-548. doi:10.1111/j.1365-3059.2005.01212.x
[19] M. R. Rademacher, J. Rumbolz and W. D. Gubler, “Evidence for Early Colonisation of Grape Buds by Uncinula necator,” Phytopathology, Vol. 91, 2002, p. S74.
[20] J. P. Peros, T. H. Nguyen, C. Troulet, C. Michel-Romiti and L. Notteghem, “Assessment of Powdery Mildew Resistance of Grape and Erysiphe necator Pathogenicity Using a Laboratory Assay,” Vitis, Vol. 45, 2006, pp. 29-36.
[21] J. Montarry, P. Cartolaro, S. Richard-Cervera and F. Delmotte, “Spatio-Temporal Distribution of Erysiphe necator Genetic Groups and Their Relationship with Disease Levels in Vineyards,” European Journal Plant Pathology, Vol. 123, No. 1, 2009, pp. 61-70. doi:10.1007/s10658-008-9343-9
[22] J. Montarry, P. Cartolaro, F. Delmotte, J. Jolivet and L. Willocquet, “Genetic Structure and s Aggressiveness of Erysiphe necator Populations during Grapevine Powdery Mildew Epidemics,” Applied and Environmental Microbiology, Vol. 78, 2008, pp. 6327-6332. doi:10.1128/AEM.01200-08

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