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Pinewood nematode (PWN), Bursaphelenchus xylophilus, the causal agent of pine wilt disease, is an inhabitant of native pine species of North America, where its presence has minor impact. In contrast, the introduction of this nematode to forests in Asia and Europe has devastated some pine stands and is recognized as a pest of significant phytosanitary concern by the National Plant Protection Organizations of several countries. The ability to detect PWN in internationally traded wood products is crucial to reduce the spread of this organism. Currently, the majority of molecular techniques for the detection of PWN rely on the presence of genomic DNA and thus fail to differentiate between living and dead PWN. The detection of dead nematodes could lead to unnecessary trade disruption. Therefore, accurate techniques for the detection of and differentiation between living and dead PWN are critical. We have developed a reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay, which specifically identifies living PWN in wood by detecting the presence of mRNA encoding an expansin gene as a viability marker. This diagnostic method was found to be more sensitive, faster and less dependent on expensive laboratory equipment than PCR. In addition, unlike PCR, it allows for simple colour detection of amplification products. This method will help resolve disputes over the detection of PWN by clarifying whether it originates from live or dead organisms. Where approved treatments are implemented, unnecessary trade disruption will be avoided, thus protecting market access of wood products from PWN-infested areas. [ABSTRACT FROM AUTHOR]

A survey of nematodes associated with branches of cork oak, Quercus suber, a species in decline since the second half of the 20th century, was conducted on two farms located in Alentejo, Portugal. Using specific morphological characters, some nematodes were identified as belonging to the genus Laimaphelenchus and one of the isolates being identified as L. heidelbergi. This research aimed to characterize the Portuguese L. heidelbergi isolate using morphobiometrical and molecular analyses and to analyze its phylogenetic relationship to other Laimaphelenchus spp. Morphometric and morphological characteristics of L. heidelbergi females and males were similar to the original description. For molecular analyses, the mitochondrial DNA region from the cytochrome oxidase subunit I and the D2/D3 expansion segments of the large subunit of rDNA were amplified and sequenced. In phylogenetic analyses, sequences of the Portuguese L. heidelbergi isolate clustered with sequences from the Australian isolate. Laimaphelenchus heidelbergi was originally described from wood of Pinus radiata growing in Australia and is here reported for the first time in Europe and Portugal. Cork oak is a new host record for L. heidelbergi. [ABSTRACT FROM AUTHOR]

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We studied the effect of climate warming on Heterobasidion root rot in boreal forests by measuring respiration activity of pure cultures of Heterobasidion parviporum in Norway spruce ( Picea abies) sawdust and by linking these data to temperature data obtained from three spruce forests located along a north-south transect stretching from northern Germany to northern Finland. The pure cultures applied in this investigation were homokaryotic, but in a separate investigation, we found no significant difference between the activity of homo- and heterokaryotic isolates. We also found that the temperature response curves of growth and respiration rates of this fungus were similar and propose that respiration reflects the general activity of H. parviporum. The respiration data were scaled up to annual cumulative respiration activity using daily temperature measurements from soil and air in the spruce forest sites. The annual respiration activity of H. parviporum showed a linear relationship with the average annual air temperature. An increase in the annual air temperature by 5°C would raise the annual activity of H. parviporum in spruce roots in northern Finland, southern Finland and northern Germany by 91%, 53% and 40%, respectively. This increase remains below the predicted increase in forest growth in northern Finland but exceeds considerably the predictions for southern Finland. According to the previous literature, a number of other decay fungi show a similar activity response to temperature as H. parviporum, suggesting that this result can be generalized to decay fungi with similar ecological habits. [ABSTRACT FROM AUTHOR]

Bursaphelenchus fungivorus is reported for the first time in Portugal, identified as associated with Pinus pinaster bark and characterized on the basis of morphological and morphometrical characters for this species. Species identification was confirmed using restriction fragment length polymorphism analysis and sequencing of the internal transcribed spacer ( ITS) regions of ribosomal DNA. Intraisolate genetic variability was detected among ITS sequences of the Portuguese B. fungivorus isolate. Phylogenetic analysis, obtained from multiple sequence alignment between ITS sequences of Bursaphelenchus species, revealed that the Portuguese B. fungivorus isolate clusters with other B. fungivorus isolates, forming a separate group close to B. seani highlighting a molecular proximity of these two species. [ABSTRACT FROM AUTHOR]

A survey to identify ophiostomatoid fungi that infect wounds on native Norwegian and Swedish broadleaved trees was undertaken during summer 2004. A fungus resembling a species of Sporendocladia was commonly isolated from the exposed cambium and inner bark of wounds. Morphological examination and comparisons of DNA sequence data for the ITS and 5.8 S regions of the rRNA gene region led to its identification as Sporendocladia bactrospora. Pathogenicity trials on young Populus tremula and Betula pubescens trees showed that S. bactrospora is capable of causing lesions on these trees. There have been few previous reports of S. bactrospora, and in most cases, these have been as saprophytes on wood. In contrast, results of this study show that it is a common inhabitant of freshly made wounds on native broadleaved trees in Scandinavia, and it appears to contribute to staining of wood. [ABSTRACT FROM AUTHOR]