The Bursaphelenchus mucronatus, which was highly similar with Bursaphelenchus xylophilus in terms of morphological characteristics and biological properties—but had weaker pathogenicity to forests—was a native species often displaced by B. xylophilus when occupying the same niche. Since the draft genome of the invasive B. xylophilus has been published, the absence of a reference genome of B. mucronatus still prevents us from understanding the molecular evidences behind competitive displacement. In this study, we employed Single Molecule, Real-Time (SMRT) sequencing and a Hi-C scaffolding approach to yield a near chromosome-level assembly of B. mucronatus, including six pseudo-chromosomes. The assembly size is 73 Mb, with scaffold N50 of 11.50 Mb and contig N50 of 1.48 Mb. Comparative genomics results showed high similarity between B. xylophilus and B. mucronatus. However, the losing of orphan genes and species-specific orthologous genes in B. mucronatus may indicate weaker adaptability to the environment. The gene family contractions of GPCRs (G Protein-Coupled Receptors) and cellulases in B. mucronatus may jointly contribute to its displacement by B. xylophilus. Overall, we introduced a valuable genomic resource for molecular and evolutionary studies of B. mucronatus, especially for studying the competitive displacement by the pinewood nematode, which could help us control the pathogenicity of pine wilt diseases.

中文翻译：

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Bursaphelenchus mucronatus 的参考基因组为揭示松材线虫的位移提供了新的资源

Bursaphelenchus mucronatus 与松材线虫在形态特征和生物学特性方面高度相似，但对森林的致病性较弱，是一种本土物种，在占据同一生态位时经常被松材线虫取代。由于侵入性松材线虫的基因组草图已经发表，由于缺乏松材线虫的参考基因组，我们仍然无法理解竞争性置换背后的分子证据。在这项研究中，我们采用单分子、实时 (SMRT) 测序和 Hi-C 支架方法来产生近染色体水平的 B. mucronatus 组装，包括六个假染色体。组装大小为 73 Mb，支架 N50 为 11.50 Mb，contig N50 为 1.48 Mb。比较基因组学结果显示 B. 松材线虫和 B. mucronatus。然而，B. mucronatus 中孤儿基因和物种特异性直系同源基因的丢失可能表明对环境的适应性较弱。B. mucronatus 中 GPCR（G 蛋白偶联受体）和纤维素酶的基因家族收缩可能共同导致其被松材线虫置换。总体而言，我们为 B. mucronatus 的分子和进化研究引入了宝贵的基因组资源，特别是用于研究松材线虫的竞争性置换，这可以帮助我们控制松枯病的致病性。mucronatus 可能共同导致其被松材线虫取代。总体而言，我们为 B. mucronatus 的分子和进化研究引入了宝贵的基因组资源，特别是用于研究松材线虫的竞争性置换，这可以帮助我们控制松枯病的致病性。mucronatus 可能共同导致其被松材线虫取代。总体而言，我们为 B. mucronatus 的分子和进化研究引入了宝贵的基因组资源，特别是用于研究松材线虫的竞争性置换，这可以帮助我们控制松枯病的致病性。