DIVERSITY OF OOMYCETE SPECIES IN THE RIPARIAN ECOSYSTEM OF ISKAR GORGE
KALOYAN KOSTOV*, PETYA CHRISTOVA, ANETA LYUBENOVA, SLAVTCHO SLAVOV
AgroBioInstitute, 8 Dragan Tsankov Blvd., 1164 Sofia, Bulgaria
*Corresponding author: kkostov@abi.bg
Keywords: Oomycete, diversity, Phytophthora, Phytopythium, Pythium
Abstract: The fungus-like oomycete organisms are often associated with inland waters and riparian ecosystems. Some of them are primary saprophytes utilizing plant debris. Others are able to infect different plant species causing diseases, occasionally with devastating intensity. Rivers are major environment and distribution route of these organisms and as such their presence and composition in the inland waters is a subject of intensive research in the last years. In order to study the diversity of the oomycete species, with an accent to those which belong to genus Phytophthora, in the longest river in Bulgaria - Iskar, we have used a "baiting" method to catch swimming zoospores. "Baits" were placed in the river at 7 locations along the Iskar Gorge. The collected isolates were grown on nutrient media for their morphological and genetic characterization. As a result, we have found species of 3 genera - Phytophthora, Phytopythium and Pythium with respectively 3 (Phytophthora lacustris, Phytophthora gonapodyides, Phytophthora chlamydospora), 2 (Phytopythium litorale, Phytopythium montanum) and 1 (Pythium sp.) representatives. All the above Phytophthora species are phylogenetically related as members of clade 6, the representatives of which are commonly isolated from rivers. Some of these species had demonstrated weak to moderate pathogenicity against several plant species in controlled experiments. Most of the oomycete species we found are probably natural inhabitants of the studied riparian ecosystem. No quarantine species have been found