title: Molecular Phylogeny of Geographical Isolates of Bursaphelenchus xylophilus: Implications on the Origin and Spread of this Species in China and Worldwide.
abstract: The genetic diversity and phylogeny of 26 isolates of Bursaphelenchus xylophilus from China, Japan, Portugal and North America were investigated based on the D2/3 domain of 28S rDNA, nuclear ribosomal Internal Transcribed Spacer (ITS) sequences, and random amplified polymorphic DNA (RAPD) analysis. The genetic diversity analysis showed that the D2/3 domain of 28S rDNA of isolates of B. xylophilus from China, Portugal, Japan and the US were identical and differed at one to three nucleotides compared to those from Canada. ITS sequences of isolates from China and Portugal were the same; they differed at one or two nucleotides compared to those of Japanese isolates and at four and 23 nucleotides compared to those from the US and Canada, respectively. The phylogenetic analysis indicated that Chinese isolates share a common ancestor with one of the two Japanese clades and that the Canadian isolates form a sister group of the clade comprised of isolates from China, Portugal, Japan, and the US. The relationship between Japanese isolates and those from China was closer than with the American isolates. The Canadian isolates were the basal group of B. xylophilus. This suggests that B. xylophilus originated in North America and that the B. xylophilus that occurs in China could have been first introduced from Japan. Further analysis based on RAPD analysis revealed that the relationship among isolates from Guangdong, Zhejiang, Shandong, Anhui provinces and Nanjing was the closest, which suggests that pine wilt disease in these Chinese locales was probably dispersed from Nanjing, where this disease first occurred in China.
authors.affiliation: Department of Zoology, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China. Key laboratory of Monitoring and Management of Plant Disease and Insects, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China. Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, China.
authors.forename: Keyun
authors.initials: K
authors.lastname: Zhang
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.forename: Jie
authors.initials: J
authors.lastname: Sun
authors.forename: Jingrui
authors.initials: J
authors.lastname: Liu
authors.forename: Kan
authors.initials: K
authors.lastname: Fei
authors.forename: Chongxing
authors.initials: C
authors.lastname: Zhang
authors.forename: Mingxu
authors.initials: M
authors.lastname: Xu
authors.forename: Jing
authors.initials: J
authors.lastname: Sun
authors.forename: Xiyuan
authors.initials: X
authors.lastname: Ma
authors.forename: Ren
authors.initials: R
authors.lastname: Lai
authors.forename: Yidong
authors.initials: Y
authors.lastname: Wu
authors.forename: Maosong
authors.initials: M
authors.lastname: Lin