Recent new outbreaks of Bursaphelenchus xylophilus in Spain and adverse pine wilt disease expansion forecasts must be met with rapid advances in genetic breeding against this pathogen. The optimal approach for breeding trees that are more resistant to pine wilt disease is to use the most virulent isolates in inoculation assays. A series of controlled inoculation experiments on Botrytis cinerea cultures, along with Pinus pinaster and P. radiata branch sections and seedlings, was conducted to investigate differences among seven virulent B. xylophilus isolates of diverse geographic origin (USA745 from USA, KA4 and S10 from Japan, Pt52T and Pt72CH from Portugal, SpPO1 and SpSA1 from Spain). Results from the experiments showed significant differences among B. xylophilus isolates. The virulence classification of the isolates studied differed for P. pinaster and P. radiata, indicating that PWN isolates vary according to host specificity. Isolates Pt52T and SpP01 proved the most virulent to P. pinaster, so either of them could be used as ‘test isolates’ in future assays to identify resistant or tolerant genotypes. For P. radiata, any isolate except SpSA1 could be used, as all the others were more virulent and all presented the same significant level of virulence. The results indicate that use of P. pinaster branch sections, rather than P. radiata branch sections or multiplication assays on B. cinerea, could be an accurate, time‐saving method for evaluating virulence levels of new B. xylophilus isolates.

中文翻译：

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松树和辐射松幼苗中7种致病性松材线虫的毒力及其与繁殖的关系

在西班牙，最近爆​​发的新近爆发的Bursaphelenchus xylophilus和不利的松树枯萎病扩大预测，必须通过针对这种病原体的基因育种迅速进行。育种对松树枯萎病更具抗性的最佳方法是在接种试验中使用最具毒力的分离株。在灰葡萄孢菌，松树松和P.上进行一系列受控接种实验。 进行了辐射分枝切片和幼苗研究，以研究7种有毒B的差异。 木糖分离株具有不同的地理来源（美国的USA745，日本的KA4和S10，葡萄牙的Pt52T和Pt72CH，西班牙的SpPO1和SpSA1）。实验结果表明B之间存在显着差异。 木糖分离物。P的研究菌株的毒力分类不同。 海岸松和P。 radiata，表明PWN分离株根据宿主特异性而异。分离株Pt52T和SpP01被证明对P的毒性最大。 pinaster，因此它们中的任何一个都可以在将来的测定中用作“测试分离株”，以鉴定抗性或耐受性的基因型。对于P。 辐射，可以使用除SpSA1以外的任何分离株，因为所有其他分离株的毒性都更高，并且都呈现出相同的显着水平的毒力。结果表明，使用P。 松树分支部分，而不是P。 辐射分支切片或B上的增殖试验。 灰霉病可能是评估新B毒力水平的准确，省时的方法。 木糖分离物。