Bursaphelenchus xylophilus: opportunities in comparative genomics and molecular host–parasite interactions

Abstract

SUMMARY Most Bursaphelenchus species are fungal feeding nematodes that colonize dead or dying trees. However, Bursaphelenchus xylophilus, the pine wood nematode, is also a pathogen of trees and is the causal agent of pine wilt disease. B. xylophilus is native to North America and here it causes little damage to trees. Where it is introduced to new regions it causes huge damage. The most severely affected areas are found in the Far East but more recently B. xylophilus has been introduced into Portugal and the potential for damage here is also high. As incidence and severity of pine wilt disease are linked to temperature we suggest that climate change is likely to exacerbate the problems caused by B. xylophilus and, in addition, will extend (northwards in Europe) the range in which pine wilt disease can occur. Here we review what is currently known about the interactions of B. xylophilus with its hosts, including recent developments in our understanding of the molecular biology of pathogenicity in the nematode. We also examine the potential developments that could be made by more widespread use of genomics tools to understand interactions between B. xylophilus, bacterial pathogens that have been implicated in disease and host trees.

Functional analysis of the cellulose gene of the pine wood nematode, Bursaphelenchus xylophilus, using RNA interference

“…RNAi has been used to investigate gene function in B. xylophilus (Wang et al, 2007;Park et al, 2008). RNAi offers the possibility to analyze gene function in vitro on a routine basis; although the molecular biology of the interactions between B. xylophilus and its host at a molecular level and the molecular basis of the pathogenicity of the nematode are still poorly understood (Jones et al, 2008). Park et al (2008) compared three methods of transferring dsRNA into B. xylophilus and found that microinjection was the most efficient, compared to soaking and electroporation.…”

The pinewood nematode, Bursaphelenchus xylophilus, in Madeira Island

“…Any uncut wilted tree and untreated dead wood can be a reservoir of nematodes, as well as insects, for the following year as insect vectors will emerge carrying large numbers of nematodes (Schrader & Unger, 2003;Jones et al, 2008). The complex ecology of B. xylophilus …”

“…Serious PWD symptoms are associated with higher temperatures, occurring only where average summer temperatures exceed 20ºC (Jones et al, 2008). In Madeira Island, after the first detection of PWN, an intensive survey has been conducted to evaluate the distribution of the nematode throughout the island and the PWN was detected in 22.8 % of the analysed 500 P. pinaster wood samples.…”

Genetic diversity of ITS sequences of Bursaphelenchus xylophilus

“…However, native American conifers are tolerant or resistant to B. xylophilus, and consequently this nematode has caused little damage (Mamiya, 1983;Jones et al, 2008). At the beginning of the 20th century, the PWN was introduced in Japan and became responsible for massive mortality of native pine trees (Pinus densiflora, P. thunbergii and P. luchuensis).…”