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ABSTRACT: To validate a real-time PCR method for the detection of Phytophthora ramorum, an intra-laboratory procedure was developed. The specificity of the TaqMan probe/primer sets was determined by carrying out real-time PCR on total DNA extracted from pure culture of several Phytophthora species. The limit of detection and the potential effects of plant substrates were evaluated by conducting the test on total DNA from healthy plant materials (Rhododendron spp., Viburnum spp. and Pieris spp.) spiked with known amounts of P. ramorum genomic DNA. The PCR efficiency was estimated through the linear regression of the dilution curve. Precision of the TaqMan assay was assessed on material from a single artificially infected plant (Rhododendron spp.). Two kinds of tissues were tested: a severely infected twig and an apparently healthy leaf. Intra-assay repeatability was evaluated on 10 replicates of the same DNA sample analysed in a single assay. Inter-assay reproducibility was evaluated on the same DNA sample amplified over five separate assays while the intersample reproducibility was evaluated on separate DNA extractions of four samples from both plant tissues amplified in a single assay.
Bulletin OEPP/EPPO Bulletin 11/2006; 36(2):409 - 414.
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ABSTRACT: In order to evaluate the role of river water on the spread of the alder disease caused by Phytophthora alni, water samples were collected at different periods of the year 2004 in two rivers displaying contrasting biological quality indices. Sporangia were produced from isolates of P. alni belonging to the three subspecies, at the river temperature (between 8 and 15 degrees C according to the sampling period). The sporulation efficiency was evaluated according to a scale of 0-9, based on the amount of sporangia produced on mycelium plugs immersed in the water for two days. Sporulation was also evaluated in river water sterilised by filtration. The amount of sporangia increased with the water temperature for both rivers, regardless of the biological quality. No sporangium was produced at the lowest temperature (8 degrees C). Sterilisation of the water drastically reduced the sporangia-stimulating effect for most of the P. alni isolates.
Communications in agricultural and applied biological sciences 02/2006; 71(3 Pt B):873-80.
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ABSTRACT: Isolates of alder Phytophthora were collected in the southern part of Belgium on riverbanks planted with Alnus glutinosa and A. incana. They were compared with strains isolated in other European countries in terms of maximum temperature for growth, oogonia shape, pathogenicity on Alnus seedlings and genetic traits. Using both molecular techniques [random amplified polymorphic DNA (RAPD) and random amplified microsatellite (RAMS)], two groups of isolates were identified, the first group being further divided into two subgroups, Ia and Ib, using RAPD. Most of the Walloon alder Phytophthora isolates as well as the standard type from UK (formally designated P. alni subsp. alni) fell into group Ia. One isolate was classified in group Ib with the German and Dutch variants (P. alni subsp. multiformis), while three isolates were placed with the Swedish variant (P. alni subsp. uniformis) in group II. In terms of morphological properties, isolates from groups Ia and Ib developed colonies with a felt-like appearance and usually produced numerous oogonia, varying from wavy to warty after 1 week (group Ia) or 2–3 weeks (Ib) in darkness. In contrast, colonies from group II isolates were generally irregular, and smooth oogonia were produced in low quantities after approximately 1 month in culture. A polymerase chain reaction (PCR) using sequence-characterized amplification region (SCAR) primers derived from a polymorphic amplification product generated with a RAPD primer was developed for the specific detection of alder Phytophthora. The specificity and sensitivity of this test are discussed here.
Journal of Phytopathology 01/2005; 153(2):99 - 107. · 0.79 Impact Factor
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Geoscience and Remote Sensing Symposium, 1991. IGARSS '91. Remote Sensing: Global Monitoring for Earth Management., International; 07/1991
