The process of epithelial cell death in Pinus thunbergii caused by the pine wood nematode, Bursaphelenchus xylophilus

Nematology ◽  
2014 ◽  
Vol 16 (6) ◽  
pp. 663-668 ◽  
Author(s):  
Joung A. Son ◽  
Joung A. Son ◽  
Taizo Hogetsu ◽  
Joung A. Son ◽  
Taizo Hogetsu ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Bursaphelenchus Xylophilus ◽  
Pinus Thunbergii ◽  
Pine Wood Nematode ◽  
Stem Cuttings ◽  
Pine Wood ◽  
A New Technique ◽  
Resin Canals ◽  
Epithelial Cell Death

This study describes a new technique to investigate how the pine wood nematode (PWN), Bursaphelenchus xylophilus, kills pine epithelial cells. After inoculating PWN into 20-cm-long Pinus thunbergii stem cuttings and incubating for 1, 3 or 7 days, the cuttings were split into 2.5 cm segments. The segments were tangentially cut so that the epithelia of several cortical resin canals were exposed, and these were stained with Evans Blue for the detection of dead epithelial cells. While almost no dead epithelial cells were found in the cortical resin canals of non-PWN-inoculated control cuttings up to day 7 of the experiment, dead epithelial cells were distributed sparsely in the epithelium of cortical resin canals throughout pine cuttings inoculated with PWN 1, 3 and 7 days after inoculation. The sparse and sporadic distribution of dead pine cells in the epithelium suggested that individual PWN attacked one epithelial cell at a time with its stylet and migrated between attacks.

Influence of fungi on multiplication and distribution of the pine wood nematode, Bursaphelenchus xylophilus, in axenized Pinus thunbergii cuttings

Nematology ◽  
2005 ◽  
Vol 7 (6) ◽  
pp. 809-817 ◽  
Author(s):  
Kazuo Suzuki ◽  
Daisuke Sakaue ◽  
Toshihiro Yamada ◽  
Yu Wang
Keyword(s):  
Population Size ◽  
Early Stage ◽  
Bursaphelenchus Xylophilus ◽  
Pinus Thunbergii ◽  
Disease Development ◽  
Pine Wood Nematode ◽  
Pine Wood ◽  
Inoculation Site ◽  
Fungal Hyphae ◽  
Close Relationship

AbstractInfluence of fungi on multiplication and distribution of the pine wood nematode (PWN), Bursaphelenchus xylophilus, was investigated in Pinus thunbergii cuttings. Axenized nematodes and/or one of two fungi isolated from healthy and PWN-killed P. thunbergii were inoculated together into autoclaved cuttings. A close relationship between the existence and distribution of fungal hyphae, and the multiplication and distribution of PWN was observed. The PWN did not multiply when only axenized nematodes were inoculated in the absence of fungi. When fungi were present, PWN population size increased markedly. The number of nematodes was high at sites where fungal hyphae were distributed. It is suggested that the restriction of a large portion of the nematode population near the inoculation site during the early stage of disease development is closely related to restricted distribution of fungal hyphae.

Role of resin canals in the early stages of pine wilt disease caused by the pine wood nematode

1997 ◽  
Vol 75 (2) ◽  
pp. 346-351 ◽  
Author(s):  
Kyoko Ishida ◽  
Taizo Hogetsu
Keyword(s):  
Pine Wilt Disease ◽  
Wilt Disease ◽  
Pinus Thunbergii ◽  
Pine Wood Nematode ◽  
Pine Wood ◽  
Pine Wilt ◽  
Bark Peeling ◽  
Resin Canals ◽  
Cut Surface

The role of cortical resin canals in the early development of a pine wilt disease in Japanese black pine, Pinus thunbergii, was studied. A part of the bark of a 2 cm long segment from a current-year stem was removed by a tangential cut with a razor blade. Both cortex-exposed segments with cut cortical resin canals (designated as +RC segments) and those without cut resin canals (–RC segments) were obtained by chance. When a virulent nematode isolate (S6-1) was inoculated onto the cut surface, the surface of the +RC segments turned brown 4 d after inoculation, and in some segments this browning occurred more intensely around cortical resin canals. When segments were cut transversely at the middle, the transverse cut surface of the inoculated +RC segments was brown and fragile, but that of the inoculated –RC segments was pale green and stable, as was that of the non-inoculated controls. Correspondingly, tissue cells including epithelial cells of the cortical resin canal of the +RC segments were all dead, but those of the –RC segments and the controls were alive. When nematodes were inoculated onto the inner surface (cambium side) of a bark peeling at which cambial xylem cells were exposed, they did not kill the cambial cells. When inoculated on the transverse cut end of a bark peeling from which nematodes would enter resin canals, nematodes killed all cells in the peeling. The above results indicate that nematodes do not kill cortical cells immediately after inoculation but become harmful to pine cells after living in cortical resin canals. Key words: Bursaphelenchus xylophilus, pine wilt disease, pine wood nematode, Pinus thunbergii, resin canal.

Distribution and pathogenicity of bacteria species carried by Bursaphelenchus xylophilus in China

Nematology ◽  
2003 ◽  
Vol 5 (6) ◽  
pp. 899-906 ◽  
Author(s):  
Bo Guang Zhao ◽  
Hu Li Wang ◽  
Su Fen Han ◽  
Zheng Ming Han
Keyword(s):  
Pine Wilt Disease ◽  
Bursaphelenchus Xylophilus ◽  
Wilt Disease ◽  
Pinus Thunbergii ◽  
Automatic Testing ◽  
Pine Wood Nematode ◽  
Field Inoculation ◽  
Pine Wood ◽  
Pine Wilt

Abstract Bacteria carried by the pine wood nematode (PWN), Bursaphelenchus xylophilus, from both healthy and diseased Pinus thunbergii and P. massoniana were studied in five main pine wilt disease epidemic provinces in P. R. China. No bacteria were found in healthy pines but were found on PWN from all samples collected from diseased trees. Twenty-four bacteria strains were isolated from the nematodes and were identified by a combination of classical and automatic testing bacteriology (ATB) expression methods. Bioassay showed that 17 of the 24 identified strains produced phytotoxins. Eleven of these 17 phytotoxin producers belonged to the genus Pseudomonas. Glasshouse and field inoculation tests using sterile techniques showed that both PWN and the toxin-producing bacteria carried were necessary to induce disease. We hypothesise that pine wilt disease is a complex, induced by both PWN and the bacteria it carries.

Cortical responses in Japanese black pine to attack by the pine wood nematode

1993 ◽  
Vol 71 (11) ◽  
pp. 1399-1405 ◽  
Author(s):  
Kyoko Ishida ◽  
Taizo Hogetsu ◽  
Kenji Fukuda ◽  
Kazuo Suzuki
Keyword(s):  
Early Stage ◽  
Bursaphelenchus Xylophilus ◽  
Black Pine ◽  
Pine Wood Nematode ◽  
Cortical Tissue ◽  
Pine Wood ◽  
Virulent Isolate ◽  
Bursaphelenchus Mucronatus ◽  
Resin Canals ◽  
Avirulent Isolate

Anatomical and cytochemical changes in the current-year stem cuttings of Japanese black pine (Pinus thunbergii) were investigated in the early stage of infection by a virulent isolate and an avirulent isolate of pine-wood nematode (Bursaphelenchus xylophilus), and an avirulent isolate of another nematode species, Bursaphelenchus mucronatus. Accumulation of lignin- and suberin-like substances around the resin canals in the cortex was shown as a new symptom of the infection by these isolates. Experiments with girdled cuttings demonstrated that more nematodes inhabit and move in the bark than in the xylem and pith at the early stage of infection by the virulent isolate. Death of pine cells occurred first in the epithelial cells of resin canals in the cortex after inoculation with the virulent isolate and then in the cortex and periderm, pith and xylem, and finally the cambium. In branches of 5-year-old seedlings inoculated with avirulent and B. mucronatus isolates, wound periderm was formed surrounding resin canals in the cortex, and cortical cells surrounding the wound periderm were alive. Evidence indicates that nematodes first enter resin canals in the cortex and then invade the surrounding cortical tissue, and that the ability of the virulent nematodes to move into the cortical tissue may be greater than that of the other isolates, accounting for differences in virulence. Key words: Bursaphelenchus xylophilus, Bursaphelenchus mucronatus, virulence, periderm, pine wilt disease, pine-wood nematode.

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