Transcriptomics and coexpression network profiling of the effects of levamisole hydrochloride on Bursaphelenchus xylophilus

Bursaphelenchus xylophilus is one of the most dangerous forest pathogens in the world, causing devastating pine forest deaths with considerable economic losses. In this study, we investigated the B. xylophilus RNA sequence responses of two different concentrations of levamisole hydrochloride (LH). We observed that body-wall muscle twitching, paralysis and, ultimately, death. 2.5 mg/ml and 3.5 mg/ml LH have toxicological effects on B. xylophilus, with mortality increasing significantly with concentration (p < 0.05). RNA sequencing, differential gene expression analysis, and cluster analysis were performed, and 336, 384, 6 genes with significant variance in expression were identified. Gene Ontology annotation and Kyoto Encyclopedia of Genes and Genomes pathway analyses of the 12 intersecting genes revealed that these genes are mostly involved in metabolism of xenobiotics and have essential roles in drug sensitivity. Through the trend analysis of DEGs, it was divided into 8 modules, and the significant modules were selected to construct the co-expression network as the central genes of the drug metabolism-cytochrome P450 pathway (ko00982) and metabolism of xenobiotics by cytochrome P450 (ko00980). Eight highly related genes were identified, including cuticle collagen, cystathionine beta-synthase, endochitinase, pyruvate dehydrogenase E1 component subunit beta, aldehyde dehydrogenase, lipase, and zinc metalloproteinase. The expression levels of these genes were upregulated significantly at low concentrations and were significantly related to the resistance of B. xylophilus to LH. This study shows that B. xylophilus gene family expansions occurred in xenobiotic detoxification pathways through gene expression and potential horizontal correlated gene transfer with LH and helps to elucidate LH lethality and the evolutionary mechanisms underlying the adaptations of B. xylophilus to the environment. These results contributing to our understanding of B. xylophilus under LH and provide a data platform to providing a basis for its control.