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The pinewood nematode (PWN), Bursaphelenchus xylophilus, is the causal agent of pine wilt disease (PWD). This nematode is considered to be an indigenous to North America and was introduced to Japan in the late 19th century. Subsequently, it has spread throughout Japan and in many other countries, China, Taiwan, and South Korea. In 1999, B. xylophilus was discovered in Portugal, and in 2008 in Spain. So far the studies have revealed that the pathogenicity of B. xylophilus varies between different isolates. The conducted study compared the pathogenicity of five isolates of B. xylophilus, originating from different parts of Japan, to 3-year-old Pinus sylvestris, and their ability to reproduce in the seedlings. The results revealed diverse virulence of B. xylophilus resulting in plant mortality. Three isolates S10, Ka4, and T4 caused 100% mortality of plants within three months while at the same time, the other two isolates, C14-5 and OKD-1 did not cause any disease symptoms on plants. After seven months, some dieback occurred on two seedlings, but similar symptoms were also found on the control plant. Moreover, a significant positive correlation was found between nematode virulence and the number of nematodes reproducing on pine seedlings.
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Pine wilt disease caused by pine wood nematodes is endemic to North America. Pine wood nematodes have already spread to East Asia, including China, Taiwan and Korea in addition to Japan. The pine wood nematode, Bursaphelenchus xylophilus, was discovered in Portuguese pine forests in 1999. If it were to become established in the pine forests in Europe, it could become one of the most serious threat to coniferous forests worldwide.
First outbreaks of the pine wood nematode in Portugal and in Europe were reported in May 1999 on the Setúbal Peninsula (about 30 km from Lisbon) on Pinus pinaster. The demarcated zone originally 306 000 ha, currently covers the whole Portuguese mainland and the Island of Madeira. In Spain this nematode was reported first time in Nevember 2008 in Extramadura region (close to the border with Portugal) on one tree of Pinus pinaster with the symptoms of the pine wilt disease. In Portugal the current efforts to reduce the pine wood nematode spread are not effective enough. Because of a risk of the pine wood nematode occurrence in other part of Europe, all countries of the European Union take action to prevent further spread of the nematode on their territory.
Both native European species, Bursaphelenchus mucronatus and B. fraudulentus, are relatively common and harmless to trees. They belong to the xylophilus group, which includes also the quarantine pest B. xylophilus – the causal agent of the pine wilt disease. They can be difficult to distinguish morphologically from each other and from B. xylophilus. Therefore, reliable methods of taxonomic identification of these species are therefore of particular interest to plant quarantine services. PCR amplification with specific primers enables rapid and precise species identification, even from a single nematode. In 2004, Matsunaga and Togashi designed specific primers for B. xylophilus and B. mucronatus. The aim of this study was to design specific primers for B. fraudulentus. The specificity of the newly designed primers was tested on eight isolates of B. fraudulentus which originated from different parts in Europe (Austria, Germany, Poland, Russia and Ungarn). For all isolates, PCR amplification resulted in products of identical length of 617 bp, but no PCR products were generated for B. xylophilus and B. mucronatus. The PCR amplification with primer sets specific for B. xylophilus (XF and XR), B. mucronatus (MF and MR) and those for B. fraudulentus (FF and FR) designed in this study resulted in amplicons of different lengths (557, 210 and 617 bp, respectively), which can be easily distinguished in agarose gels.
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Choroba wiedniecia sosny

58%
Sylwan
|
2008
|
tom 152
|
nr 12
9-19
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