Among-tree difference in the inhibition of systemic dispersal of Bursaphelenchus xylophilus (Nematoda: Aphelenchoididae) by Pinus densiflora

Abstract

The among-tree differences in the inhibition of systemic dispersal of Bursaphelenchus xylophilus by Pinus densiflora were determined. Two-year-old branches were collected from four different aspects and at two different heights from six field grown P. densiflora. The virulent isolate of B. xylophilus, T-4, was inoculated on the upper end of 5-cm-long branch sections placed upright in a glass vial. The number of nematodes passing through the sections over 24 h was counted. Daily changes in the inhibition of systemic spread of the nematode were also determined. Two-year-old branches were collected at four hour intervals for 24 h from six additional trees. These branches were then inoculated with the nematode. The number of nematodes passing through the branch sections differed among the pine trees but did not differ between the branch heights or aspects. A diurnal change in the passing nematode number was observed only for a tree which grew on the top of a steep slope.

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

“…When pine wood nematodes are soaked in dsRNA they take longer to migrate through branch sections of P. thunbergii. Differences between trees in the inhibition of dispersal and between-isolate differences in the dispersal ability of B. xylophilus have been reported (Matsunaga and Togashi, 2004). Silencing of the endo-β-1,4-glucanase gene with RNAi resulted in reducing the ability to locate and invade roots and decreased the number of established nematodes (Chen et al, 2005;Bakhetia et al, 2007).…”

Systematic Identification of the Xylophilus Group in the Genus Bursaphelenchus

“…Besides RFLP method, many species-specific PCR and real-time PCR methods were developed for B. xylophilus identification [50][51][52][53][54][55][56][57][58]. By real-time PCR [59] or loop-mediated isothermal amplification (LAMP) methods [60], B. xylophilus can be detected directly from wood.…”

Seasonal change in susceptibility of Pinus densiflora to Bursaphelenchus xylophilus infection, determined from the number of nematodes passing through branch sections

“…There were positive correlations between the total area of cortical resin canals on a cross section of P. thunbergii current year branches and the number of nematodes passing through branch sections for a resistant family and a group of unselected families (Kawaguchi, 2006). The passing nematode number differed among P. densiflora trees in a sparse stand in late August but did not differ among four aspects or between two heights within individual trees (Matsunaga & Togashi, 2004). Consequently, this method may help to evaluate the resistance level of individual pine trees; however, the mean number of passing nematodes differed between June and September, even when one nematode isolate was used (Togashi & Matsunaga, 2003).…”