The pine wood nematode Bursaphelenchus xylophilus parasitizes millions of pine trees worldwide each year, causing severe wilt and the death of host trees. Glycoside hydrolase 45 genes of B. xylophilus are reported to have been acquired by horizontal gene transfer from fungi and are responsible for cell wall degradation during nematode infection. Previous studies ignored the possibility of copy number variations of such genes. In this study, we determined that two of the glycoside hydrolase 45 genes evolved to maintain multiple copies with distinct expression levels, enabling the nematode to infect a variety of pine hosts. Additionally, tandem repeat variations within coding regions were also detected between different copies of glycoside hydrolase 45 genes that could result in changes in protein sequences and serve as an effective biological marker to detect copy number variations among different B. xylophilus populations. Consequently, we were able to further identify the copy number variations of glycoside hydrolase 45 genes among B. xylophilus strains with different virulence. Our results provide new insights into the pathogenicity of B. xylophilus, provide a practical marker to genotype copy number variations and may aid in population classification.

中文翻译：

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松材线虫糖苷水解酶45基因的拷贝数变异及其对松萎病发病的影响

每年，松木线虫Bursaphelenchus xylophilus寄生于全球数百万棵松树中，导致严重的枯萎和寄主树的死亡。木糖双歧杆菌糖苷水解酶45个基因据报道，它们是通过水平基因转移从真菌中获得的，并且是线虫感染期间细胞壁降解的原因。先前的研究忽略了此类基因的拷贝数变异的可能性。在这项研究中，我们确定了糖苷水解酶45个基因中的两个进化以维持具有不同表达水平的多个拷贝，从而使线虫能够感染各种松树宿主。另外，还在糖苷水解酶45基因的不同拷贝之间检测到编码区内的串联重复变异，这可能导致蛋白质序列的改变，并作为检测不同木糖双歧杆菌之间拷贝数变异的有效生物学标记。人口。因此，我们能够进一步鉴定具有不同毒力的木糖双歧杆菌菌株中糖苷水解酶45基因的拷贝数变异。我们的结果提供了新的见解，对木糖双歧杆菌的致病性，为基因型拷贝数变异提供了实用的标记，并可能有助于人群分类。