Evaluation of selected Cucumis sativus accessions for resistance to Pseudoperonospora cubensis in Egypt
E.I. Metwally, M.T. Rakhahttps://doi.org/10.17221/12/2015-CJGPBCitation:Metwally E.I., Rakha M.T. (2015): Evaluation of selected Cucumis sativus accessions for resistance to Pseudoperonospora cubensis in Egypt. Czech J. Genet. Plant Breed., 51: 68-74.
Downy mildew [Pseudoperonospora cubensis (Berk. & Curt.) Rostov] is a major destructive disease of cucumber (Cucumis sativus L.) worldwide. Resistant cultivars were recently introduced into Egypt, but yield losses were high if no fungicides were used. The objective of this study was to identify sources of resistance to downy mildew among Plant Introduction (PI) cucumber accessions from the U.S. National Plant Germplasm System. We evaluated 133 such accessions for downy mildew resistance under natural field epidemics during the summer 2013 at El-Beheira Governorate, Egypt. Mean ratings for downy mildew leaf damage ranged from 1 to 9 on a 0 to 9 scale. We classified 18 PI accessions (13.5%) as highly resistant (rating of 1.0–2.0), 46 (34.5%) as moderately resistant (rating 2.1–4.0), 40 (30%) as intermediate (rating 4.1–6.0), 12 (9%) as moderately susceptible (rating 6.1–7), and 17 (13%) as highly susceptible (rating > 7.1). The most resistant PI accessions were PI 432870, PI 432873, PI 432878, PI 432884, and PI 432886 with a rating of 1, which originated from China. The most susceptible PI accessions were Ames7736, PI 211979, PI 288991, PI 288992 and PI 289698 with a rating of 9. The five most resistant and five most susceptible accessions were further evaluated in replicated experiments during the summer 2014. Results from the repeated test confirmed the results from the first screening. No PI accession was found immune to downy mildew. However, high levels of resistance were observed in several PI accessions that could be useful for the breeding for resistance to P. cubensis in cucumber.Keywords:cucumber; cucurbit downy mildew, field resistance; germplasmReferences:
Block C.C., Reitsma K.R. (2005): Powdery mildew resistance in the U.S. National plant germplasm system cucumber collection. HortScience, 40: 416–420.Call A.D., Criswell A.D., Wehner T.C., Klosinska U., Kozik E.U. (2012): Screening cucumber for resistance to downy mildew caused by Pseudoperonospora cubensis (Berk. and Curt.) Rostov. Crop Science, 52: 577–592Cohen Yigal (1977): The combined effects of temperature, leaf wetness, and inoculum concentration on infection of cucumbers with Pseudoperonospora cubensis. Canadian Journal of Botany, 55, 1478-1487 https://doi.org/10.1139/b77-174El-Hafaz A., El-Din B., El-Doweny H.H., Awad M.M.W. (1990): Inheritance of downy mildew resistance and its nature of resistance in cucumber. Annals of Agricultural Science, Moshtohor, 28: 1681–1697.Holmes G., Wehner T., Thornton A. (2006): An old enemy re-emerges. American Vegetable Grower: 14–15.Kibria G., Yousuf H.A., Nugegoda D., Rose G. (2010): Climate Change and Chemicals. Environmental and Biological Aspects. New Delhi, New India Publishing Agency.Klosinska U., Kozik E.U., Call A.D., Wehner T.C. (2010): New sources of resistance to downy mildew in cucumber. In: Thies J.A., Kousik S., Levi A. (eds): Proc. Cucurbitaceae 2010, Charleston, Nov 14–18, 2010: 135–138.Komárek Michael, Čadková Eva, Chrastný Vladislav, Bordas François, Bollinger Jean-Claude (2010): Contamination of vineyard soils with fungicides: A review of environmental and toxicological aspects. Environment International, 36, 138-151 https://doi.org/10.1016/j.envint.2009.10.005Kookana R. S., Baskaran S., Naidu R. (1998): Pesticide fate and behaviour in Australian soils in relation to contamination and management of soil and water: a review. Australian Journal of Soil Research, 36, 715- https://doi.org/10.1071/S97109Lebeda A. (1999): Pseudoperonospora cubensis on Cucumis spp. and Cucurbita spp. – resistance breeding aspects. Acta Horticulturae, 492: 363–370.Lebeda Aleš, Cohen Yigal (2011): Cucurbit downy mildew (Pseudoperonospora cubensis)—biology, ecology, epidemiology, host-pathogen interaction and control. European Journal of Plant Pathology, 129, 157-192 https://doi.org/10.1007/s10658-010-9658-1Pitrat P., Blancard D., Epinat C.A. (1989): study on the variability of downy mildew and looking for sources of resistance in Cucumis melogermplasm. In: Thomas C.E. (ed.): Proc. Cucurbitaceae 89: Evaluation and Enhancement of Cucurbit Germplasm, Charleston, Nov 29–Dec 2, 1989: 137–139.SAS Institute (2011): SAS/STAT 9.3 User’s Guide. Cary, SAS Institute Inc.Shetty Nischit V, Wehner Todd C, Thomas Claude E, Doruchowski Roch W, Vasanth Shetty K.P (2002): Evidence for downy mildew races in cucumber tested in Asia, Europe, and North America. Scientia Horticulturae, 94, 231-239 https://doi.org/10.1016/S0304-4238(02)00013-4Staub J., Barczynaka H., Van Kleineww D., Palmer M., Lakowska E., Dijkhuizen A. (1989): Evaluation of cucumber germplasm for six pathogens. In: Thomas C.E. (ed.): Proc. Cucurbitaceae 89: Evaluation and Enhancement of Cucurbit Germplasm, Charleston, Nov 29–Dec 2, 1989: 149–153.Wehner Todd C., Shetty Nischit V. (1997): Downy Mildew Resistance of the Cucumber Germplasm Collection in North Carolina Field Tests. Crop Science, 37, 1331- https://doi.org/10.2135/cropsci1997.0011183X003700040050x