Oospore Germination and Formation by the Late Blight Pathogen Phytophthora infestans in vitro and under Field Conditions |
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Authors: | A Strömberg U Boström & N Hallenberg |
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Institution: | Department of Plant Biology, Swedish University of Agricultural Sciences PO Box 7080, S-750 07 Uppsala, Sweden,;Department of Ecology and Crop Production Science, Swedish University of Agricultural Sciences PO Box 7080, S-750 07 Uppsala, Sweden,;Botanical Institute, Göteborg University, PO Box 461, SE-405 30 Göteborg, Sweden |
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Abstract: | The ability of the late blight pathogen Phytophthora infestans to form oospores in leaves of seven potato cultivars was examined at different incubation temperatures under controlled environmental conditions and under field conditions. At 10°C, the oospore formation in three intermediate-resistant cultivars all differed significantly from each other (P < 0.05), with the lowest amount formed in cv. Asterix. This latter cultivar did not form oospores at any other temperature. Under field conditions oospores were formed abundantly in a naturally infected field. A significant date by cultivar interaction showed that P. infestans increased the oospore formation in foliage by time in cvs Columbo, Hertha and Matilda, whereas no significant differences between dates were found for other cultivars. The genetic structure of P. infestans in the naturally infected field plot, where oospores formed abundantly, was studied by using amplified fragment length polymorphism and a high genetic diversity was revealed. Oospore germination from two Scandinavian (A1 and A2) P. infestans isolates was stimulated in visible light and in 1 : 2 and 1 : 10 soil extract. The effect of light and nutrients on oosporogenesis is discussed. |
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Keywords: | late blight oospores potato race-non-specific resistance |
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