RESUMEN
Phytophthora species are widespread and diverse in forest ecosystems, but little is known about their ecology. We explore ecological attributes of the closely related clade 3 species that occur sympatrically in western North American forests. We address the population structure, pathology, and epidemiology of P. ilicis, P. nemorosa, P. pluvialis, P. pseudosyringae, and P. psychrophila. Phytophthora species were isolated from plant tissues, rainwater falling through the forest canopy, streams, and soils in forests in western Oregon. Species identifications were based on morphology in culture with molecular confirmation using COX spacer and internal transcribed spacer (ITS) sequences. All five clade 3 Phytophthora species are present in western Oregon forests, although P. ilicis (only 1 forest isolate) and P. psychrophila (only 12 isolates) are apparently rare. P. ilicis is known only from holly in horticultural situations and once from a naturalized seedling in an urban forest. The known distribution of P. nemorosa in forest settings coincides with the ranges of its principle hosts, tanoak and myrtlewood, in Oregon and California. Although it is regularly identified from streams within the tanoak range, it has not been recovered from streams beyond that range. P. pluvialis is primarily associated with Douglas-fir canopies. It was identified from scattered locations throughout western Oregon in rain traps beneath Douglas-fir plantations and from diseased needles. P. pseudosyringae is also isolated from tanoak and myrtlewood in southwest Oregon and California, but its distribution, in streams at least, extends throughout much of western Oregon. P. psychrophila in Oregon is known only from rain traps beneath tanoak trees. Little intraspecific variation was detected in the nuclear rDNA ITS of clade 3 species. Variation in the mitochondrial COX spacer region was more frequent, with 2 to 10 haplotypes identified in the clade 3 species, for which we had multiple isolates.
Asunto(s)
Ecosistema , Microbiología Ambiental , Bosques , Phytophthora/clasificación , Phytophthora/aislamiento & purificación , Enfermedades de las Plantas/microbiología , Análisis por Conglomerados , ADN de Algas/química , ADN de Algas/genética , ADN Espaciador Ribosómico/química , ADN Espaciador Ribosómico/genética , Técnicas Microbiológicas , Oregon , Filogenia , Phytophthora/crecimiento & desarrollo , Phytophthora/patogenicidad , Análisis de Secuencia de ADNRESUMEN
Phytophthora species were systematically sampled, isolated, identified and compared for presence in streams, soil and roots of alder (Alnus species) dominated riparian ecosystems in western Oregon. We describe the species assemblage and evaluate Phytophthora diversity associated with alder. We recovered 1250 isolates of 20 Phytophthora species. Only three species were recovered from all substrates (streams, soil, alder roots): P. gonapodyides, the informally described "P. taxon Pgchlamydo", and P. siskiyouensis. P. alni ssp. uniformis along with five other species not previously recovered in Oregon forests are included in the assemblage: P.citricola s.l., P. gregata, P. gallica, P. nicotianae and P. parsiana. Phytophthora species diversity was greatest in downstream riparian locations. There was no significant difference in species diversity comparing soil and unwashed roots (the rhizosphere) to stream water. There was a difference between the predominating species from the rhizosphere compared to stream water. The most numerous species was the informally described "P. taxon Oaksoil", which was mainly recovered from, and most predominant in, stream water. The most common species from riparian forest soils and alder root systems was P. gonapodyides.
Asunto(s)
Alnus , Ecosistema , Variación Genética , Phytophthora/clasificación , Phytophthora/genética , Ríos , Oregon , Rizosfera , Microbiología del Suelo , Microbiología del AguaRESUMEN
Phytophthora borealis and Phytophthora riparia, identified in recent Phytophthora surveys of forest streams in Oregon, California and Alaska, are described as new species in Phytophthora ITS Clade 6. They are similar in growth form and morphology to P. gonapodyides and are predominantly sterile. They present unique DNA sequences, however, and differ in temperature/growth relations and geographic distribution.
Asunto(s)
Phytophthora/clasificación , Alaska , California , ADN de Hongos/genética , ADN Ribosómico/genética , Oregon , Filogenia , Phytophthora/genética , Phytophthora/aislamiento & purificación , Phytophthora/ultraestructura , Enfermedades de las Plantas/microbiología , Análisis de Secuencia de ADN/métodos , Árboles/microbiologíaRESUMEN
Little is known about indigenous Phytophthora species in natural ecosystems. Increasing evidence, however, suggests that a diverse, trophically complex Phytophthora community is important in many forests. The number of described species has steadily increased, with a dramatic spike in recent years as new species have been split from old and new species have been discovered through exploration of new habitats. Forest soil, streams, and the upper canopies of trees are now being explored for Phytophthora diversity, and a new appreciation for the ecological amplitude of the genus is emerging. Ten to twenty species are regularly identified in temperate forest surveys. Half or more of this Phytophthora diversity comes from species described since 2000. Taxa in internal transcribed spacer (ITS) Clade 6 are especially numerous in forest streams and may be saprophytic in this habitat. Three ecological assemblages of forest Phytophthora species are hypothesized: aquatic opportunists, foliar pathogens, and soilborne fine-root and canker pathogens. Aggressive invasive species are associated with all three groups.
Asunto(s)
Phytophthora/aislamiento & purificación , Enfermedades de las Plantas/parasitología , Microbiología del Suelo , Árboles/parasitología , Ecosistema , Especies Introducidas , Phytophthora/clasificación , Phytophthora/genética , Hojas de la Planta/microbiología , Raíces de Plantas/microbiología , Ríos/microbiología , SueloRESUMEN
Health practitioners work under fiduciary constraint, and are obligated to favour patient needs over all others and in particular their own. The principles of professionalism demand that professionals take great care to ensure that boundaries are maintained safely to provide an optimal setting in facilitating patient care. Boundary violations cause serious harm to the patient. Any romantic or sexual activity between parties is the most serious form of boundary violation. The chiropractic profession is included in the list of disciplines which are at an increased risk for boundary violations. The authors propose a four stage protocol which is designed to offer all parties maximal protection beginning with undergraduate professional education and then mandatory continuing education for registrants in professional practice. The protocol would affect all aspects of professional life including training in boundaries and jurisdictional regulation.
RESUMEN
Eighteen Phytophthora species and one species of Halophytophthora were identified in 113 forest streams in Alaska, western Oregon and southwestern Oregon that were sampled by baiting or filtration of stream water with isolation on selective media. Species were identified by morphology and DNA characterization with single strand conformational polymorphism, COX spacer sequence and ITS sequence. ITS Clade 6 species were most abundant overall, but only four species, P. gonapodyides (37% of all isolates), P. taxon Salixsoil, P. taxon Oaksoil and P. pseudosyringae, were found in all three regions. The species assemblages were similar in the two Oregon regions, but P. taxon Pgchlamydo was absent in Alaska and one new species present in Alaska was absent in Oregon streams. The number of Phytophthora propagules in Oregon streams varied by season and in SW Oregon, where sampling continued year round, P. taxon Salixsoil, P. nemorosa and P. siskiyouensis were recovered only in some seasons.
Asunto(s)
Ecosistema , Phytophthora/aislamiento & purificación , Microbiología del Agua , Alaska , Secuencia de Bases , ADN de Hongos/química , ADN de Hongos/genética , ADN Mitocondrial/química , ADN Mitocondrial/genética , ADN Espaciador Ribosómico/genética , Complejo IV de Transporte de Electrones/química , Complejo IV de Transporte de Electrones/genética , Variación Genética , Datos de Secuencia Molecular , Oregon , Filogenia , Phytophthora/clasificación , Phytophthora/genética , Reacción en Cadena de la Polimerasa , Polimorfismo Conformacional Retorcido-Simple , Ríos , Alineación de Secuencia , ÁrbolesRESUMEN
Phytophthora megasperma sensu lato was a conglomeration of morphologically similar but phylogenetically unrelated species. In this paper we continue the segregation of species from the old P. megasperma complex, formally naming two previously recognized isolate groups. Isolates recovered from rosaceous fruit trees (especially apple and cherry) are in ITS clade 6, related to but distinct from P. megasperma sensu strictu. They are named here Phytophthora rosacearum. They have been referred to previously as the "AC" or "high temperature small oospore" group of P. megasperma. A second group of isolates, earlier called "soybean race non-classifiable", recovered from soybeans in Indiana and other Midwestern states, are morphologically similar to P. megasperma sensu strictu but unrelated to that species, falling in ITS clade 8. They are named here P. sansomeana. Isolates recovered from Douglas-fir seedlings in nurseries in the Pacific Northwest and various weedy hosts in New York State, referred to in earlier work as "P. megasperma DF1", appear to be conspecific with the soybean isolates, although they include certain ITS DNA polymorphisms. Both new species are supported by a combination of new and previously published morphological, growth and molecular data.
Asunto(s)
Phytophthora/clasificación , ADN de Hongos/análisis , ADN Espaciador Ribosómico/genética , Filogenia , Phytophthora/genética , Especificidad de la Especie , Esporas Fúngicas/citologíaRESUMEN
Phytophthora austrocedrae is a new species isolated from necrotic lesions of stem and roots of Austrocedrus chilensis. It is a homothallic species characterized by semipapillate sporangia, oogonia with amphigynous antheridia, and very slow growth (1-2 mm d(-1) on V-8 agar at 17.5 degrees C optimum temperature). Phylogenetic analysis of ITS rDNA sequence indicates that its closest relative is Phytophthora syringae, another species frequently isolated from soil and streams in A. chilensis forests.
Asunto(s)
Phytophthora/clasificación , Argentina , ADN de Hongos/genética , ADN Espaciador Ribosómico/genética , Filogenia , Phytophthora/genética , Phytophthora/aislamiento & purificación , Corteza de la Planta/microbiología , Enfermedades de las Plantas/microbiología , Raíces de Plantas/microbiología , Especificidad de la EspecieRESUMEN
An unknown Phytophthora species was recovered in southwestern Oregon from rhododendron and tanoak leaf baits used for monitoring streams and soils for the presence of Phytophthora ramorum, from a blighted shoot of myrtlewood and from tanoak bark cankers. Isolates of this species yielded ITS-DNA sequences that differed substantially from other Phytophthora sequences in GenBank. Morphological features also differed from available descriptions of known Phytophthora species. Based on the combination of unique morphology and unique ITS sequences a new species is proposed. The new species, Phytophthora siskiyouensis, is homothallic with globose to subglobose oogonia, which may be terminal, sessile or laterally intercalary. Antheridia are capitate and mostly paragynous but sometimes amphigynous. Oospores are mostly aplerotic. Sporangia are variable but commonly ovoid to reniform, with apical, subapical or lateral semipapillae (occasionally more than one). Sporangia are terminal, subterminal or occasionally intercalary on unbranched sporangiophores, with basal, subbasal or lateral attachment. Sporangia are weakly deciduous, with variable length pedicels. This combination of characters clearly separates Phytophthora siskiyouensis from other known Phytophthora species.