Badania miały na celu określenie patogeniczności zróżnicowanych na 3 podgatunki izolatów Phytophthora alni, otrzymanych z porażonych olszy, gleby oraz wody. W pierwszym doświadczeniu inokulowano krążkami plechy podstawę pędu 2-letnich siewek olszy czarnej. Wszystkie izolaty P. alni subsp. alni powodowały żółknięcie, brązowienie i przedwczesne opadanie liści. Najbardziej patogeniczne okazały się izolaty P. alni subsp. alni otrzymane z gleby oraz izolaty P. alni subsp. alni z Francji. Już po miesiącu od inokulacji podstawy pędu rośliny były całkowicie porażone. W drugim doświadczeniu siewki olszy wysadzano do sztucznie zakażonego podłoża. Wszystkie izolaty P. alni subsp. alni powodowały rozwój choroby, a najbardziej patogeniczne okazały się izolaty P. alni subsp. alni z gleby. Pozostałe dwa podgatunki, tj. subsp. uniformis i subsp. multiformis nie powodowały objawów chorobowych, zarówno w doświadczeniu z inokulacją podstawy pędu jak i z zakażaniem podłoża.
EN
The aim of the work was to determine pathogenicity of 3 subsp. groups of Phytophthora alni obtained from diseased alder trunks, surrounding soil and water. 2-year old alder seedlings were inoculated at the stem bases or planted in artificially infected soil. Ali isolates of P. alni subsp. alni colonized the alder stem. The most pathogenic were isolates P. alni subsp. alni obtained from soil and the weakest were isolates obtained from water. Isolates subsp. uniformis and multiformis were not able to colonize alder seedlings.
Olsza czarna (Alnus glutinosa) jest drzewem rozpowszechnionym w Polsce, szczególnie wzdłuż rzek, strumieni, jezior i stawów. Korzenie olsz żyją w symbiozie z bakteriami glebowymi, które mogą wiązać azot cząsteczkowy z powietrza i udostępniać go w postaci organicznych związków azotowych warstwie korzeniowej. Z tego powodu nasadzenia olszowe przyczyniają się do poprawy żyzności i uważane są za cenne gatunki pionierskie. Od kilkunastu lat w Polsce obserwuje się liczne zachorowania olsz. W wyniku przeprowadzonych badań z porażonych olsz oraz z ziemi otaczającej chore drzewa otrzymano 133 izolaty rodzaju Phytophthora. Amplifikacja otrzymanego DNA z zastosowaniem starterów ISSR i porównanie z izolatami referencyjnymi 11 gatunków Phytophthora pozwoliło na określenie przynależności gatunkowej patogenów. Dwadzieścia siedem zidentyfikowano jako P. alni subsp. alni, 13 jako P. cactorum oraz 21 jako P. citricola. Przynależność gatunkową potwierdzono za pomocą starterów gatunkowo-specyficznych.
EN
Common alder (Alnus glutinosa) is an important tree growing commonly in Poland. Alder trees are grown along the rivers, streams, by lakes and water ponds. Due to the symbiotic association with microorganisms, alder has a remarkable ability to fix atmospheric nitrogen, this has made it the tree of a choice for planting in recultivating areas. It is a light-demanding pioneer species which as grows as up to 90 cm per season. Decay of alder trees has been observed in Poland for over a dozen years. 133 isolates of Phytophthora spp. were obtained from diseased trunks of A. glutinosa and the surrounding soil. Isolates were screened against ISSR markers characteristic of the standard cultures of 11 Phytophthora species. Twenty seven from 133 isolates were qualified as P. alni subsp. alni, 13 as P. cactorum, 21 as P. citricola, what was confirmed by PCR using starters specific for the species.
Pathogenic oomycetes represented mainly by the species of Phytophthora genus are among the most dangerous plant pathogens. They pose a serious threat for agricultural as well as wild plants, and are involved in forest decline worldwide. Over 140 pathogenic Phytophthora species have been identified so far. The common infection symptoms include rotting of below− and aboveground parts of plants, causing weakness and slow decline of infected trees. The economic losses caused by certain Phytophthora species may rich even 100%. Globalization and border opening have facilitated the transport of plant material between countries and continents, thus increased the risk of transfer of various Phytophthora genus representatives to new geographical locations. Global warming (e.g. mild winters) have facilitated the expansion of species from southern to northern Europe. Among Polish Phytophthora isolates are species that have previously been known only in nurseries (e.g. P. cactorum), but nowadays they are also isolated from forests (e.g. oak stand in the Krotoszyn Plateau). It suggests the pathway from nurseries to stands with plant for plantings and attached soil. There are also new species, that have not been isolated so far in the world (P. polonica) or found far away from Poland (P. fragaliaefolia in Japan on strawberry). The possible natural pathways are birds and water courses. In Mazowsze and Wielkopolska regions (C and W Poland) the polyphagous P. cinnamomi was found on pedunculate oaks (Quercus robur). This species causes significant damage to red oak forest in France, but also threats Jarrah forests in the Australian ecosystem (it attacks ca. 1000 species of plants). Fortunately, in addition to time consuming and laborious classic methods of Phytophthora identification, based on morphology and physiological properties, molecular methods that are based on immunological tests and chromosomal or mitochondrial DNA markers identification have come into common use. Despite morphological similarity to true fungi, oomycetes are more closely related to diatoms and brown algae, and have several structural features that differentiate them from fungi, including the cell wall composed of cellulose instead of chitin. That is one of the reasons that fungicides have a limited use in the fight with Phytophthora infections. Additionally, type of ecological niches that are settled by pathogenic oomycetes (root remnants in soil, watercourses) hinders the chemical combating. Biocontrol, i.e. the use of interspecies interactions between microorganisms (bacteria, fungi) to limit the growth and development of pathogens, seems to be a reasonable alternative.
Common alder (Alnus glutinosa) and grey alder (Alnus incana) are distributed along streams, rivers and increasingly planted in programmes of riverbank restoration. Since over a dozen years dying of alder trees has been observed in Europe. Phytophthora spp. are the major pathogens of this plant. In 2004 Brasier at al. described new species, especially aggressive to alder as P. alni which is an interspecific hybrid between P. cambivora and P. fragariae. A new Phytophthora disease of alder is widely distributed in Europe. The paper summarizes information on the morphological characteristics, isolation procedure, modes of spreading and possibility of disease limitation.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.