Bacterial Diversity and Pathogenicity of Pine Wood Nematode (Bursaphelenchus xylophilus) from Two Diff erent Sources

Abstract

Pine wilt disease is a devastating disease of pine trees caused by a pine wood nematode (PWN), Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle. We studied the bacteria carried by B. xylophilus from Fushan Mountain and Qingdao University Campus (F and Q samples) and the pathogenicity of the two PWN samples to explore the relationship between PWN companion bacteria and its pathogenicity. Based on metagenomic analysis, the distribution of the bacteria from the two samples was signifi cantly different. At the phylum level, Proteobacteria is the largest phylum in the two samples, 85 and 65% in F and Q samples, respectively. At the family level, Enterobacteriaceae and Rhizobiaceae were dominant in F sample with the total relative abundance of 55% while the two bacterial families only accounted for 15% in Q sample. Moreover, Burkholderiaceae was only detected in F sample. PICRUSt analysis based on KEGG database showed that the bacteria carried by B. xylophilus from F sample had stronger metabolic abilities. In addition, BugBase analysis predicted that the bacteria from F sample had stronger effect on pathogenicity and antioxidant stress. Furthermore, we tested the feeding ability and pathogenicity of F and Q samples, and found that the B. xylophilus of F sample had stronger feeding ability and pathogenicity, which was consistent with the results of PICRUSt analysis based on KEGG database and BugBase analysis. Our research indicated that the pathogenicity of B. xylophilus could be closely related to the vitality of its associated bacteria, and Enterobacteriaceae, Rhizobiaceae and Burkholderiaceae belonging to Proteobacteria phylum were important pathogenicity-related bacterial families, which is valuable for the study on the pathogenesis of B. xylophilus.