Molecular polymorphisms between populations of Pseudoperonospora cubensis from Greece and the Czech Republic and the phytopathological and phylogenetic implications |
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| Authors: | P Sarris M Abdelhalim M Kitner N Skandalis N Panopoulos A Doulis A Lebeda |
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| Institution: | Laboratory of Molecular Plant Pathology and Plant Biotechnology, Department of Biology, University of Crete, GR-71004 Heraklion;;Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Hellas, PO Box 1527, GR-71110 Heraklion, Greece;;Department of Botany, Faculty of Science, PalackýUniversity in Olomouc, ?lechtitel?11, 783 71 Olomouc-Holice, Czech Republic;;and Laboratory of Plant Biotechnology, Institute of Viticulture, Floriculture &Vegetable Crops, National Agricultural Research Foundation of Greece (NAGREF), PO Box 2229, GR-71003 Heraklion, Greece |
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| Abstract: | Molecular genetic polymorphisms within Pseudoperonospora cubensis isolates of different geographic origins were investigated to establish their phylogenetic relationships and to assess genetic variability between two distant pathogen populations. Thirty isolates originating from Greece (Crete; 15), the Czech Republic (13), the Netherlands (one) and France (one) were analysed by AFLP fingerprinting and ITS 5·8S rDNA sequence analysis. All isolates were obtained from cucumber ( Cucumis sativus ) plants showing typical downy mildew symptoms. Four AFLP primer combinations produced a total of 288 high-quality bands of which 45% were polymorphic, allowing isolates to be grouped into two separate clusters: one including the Central European (Czech Republic) and Western European (the Netherlands and France) and the other the Cretan isolates. Within each AFLP cluster there was some variation, which could be accounted for by geographic origin or pathogenicity. The two populations (Cretan vs. Central and Western European) exhibited a high degree of genetic isolation. There was no clear AFLP grouping of isolates on the basis of pathotypes. No variability was detected in the ITS1 region; however, ITS2 sequences grouped P. cubensis isolates in two subclusters: one with all investigated European and the other with Asian isolates. The two subclusters formed a larger P. cubensis cluster which was differentiated from the cluster of the neighbouring species Pseudoperonospora humuli . Within P. cubensis , AFLP fingerprints could resolve genetically isolated populations, even on small or medium geographic scales, while ITS2 sequence showed differences on a global scale, being only suitable for phylogenetic analyses. |
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| Keywords: | Cucumis sativus cucurbit downy mildew genetic diversity pathotypes Pseudoperonospora humuli |
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