scholarly journals The pine wood nematode, Bursaphelenchus xylophilus, in Portugal: possible introductions and spread routes of a serious biological invasion revealed by molecular methods

Nematology ◽  
2012 ◽  
Vol 14 (8) ◽  
pp. 899-911 ◽  
Author(s):  
Vera Valadas ◽  
Marta Laranjo ◽  
Pedro Barbosa ◽  
Margarida Espada ◽  
Manuel Mota ◽  
...  

The pine wood nematode (PWN), Bursaphelenchus xylophilus, the causal agent of pine wilt disease (PWD), is a major world-wide pathogen and pest of pine, with impacts on forest health, natural ecosystem stability and international trade. In Portugal, PWN was first diagnosed in 1999, the first occurrence also for Europe. The disease was recently detected on the island of Madeira and in northern Spain. In an attempt to search for more reliable and robust molecular markers that enable the study of intraspecific variability of B. xylophilus from different geographic locations, the intergenic spacer (IGS) region of the 5S rRNA gene and inter-simple sequence repeats (ISSR) analysis were used to determine the genetic relationships among 43 B. xylophilus isolates from Portugal, China, Japan, South Korea and USA. IGS sequence analysis showed that this region can only be used to establish interspecific relationships, since no differences were detected among Portuguese isolates from different geographic locations. Fingerprints obtained with ISSR show high genetic variability among Portuguese isolates, except for the ones obtained prior to 2008. The ISSR dendrogram suggests the spread of the disease inside continental Portugal and to Madeira. Until 2008, B. xylophilus populations found in continental Portugal showed low genetic diversity, pointing to a single introduction, probably from Asia, whereas recent populations from continental Portugal (2009-2010) and Madeira show high genetic diversity, suggesting multiple introductions from different origins.

2019 ◽  
Vol 101 (2) ◽  
pp. 88-93
Author(s):  
Hanyong Zhang ◽  
Erika Okii ◽  
Eiji Gotoh ◽  
Fumihiko Miyahara ◽  
Junji Miyazaki ◽  
...  

Nematology ◽  
2005 ◽  
Vol 7 (6) ◽  
pp. 809-817 ◽  
Author(s):  
Kazuo Suzuki ◽  
Daisuke Sakaue ◽  
Toshihiro Yamada ◽  
Yu Wang

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.


Author(s):  
Yang Wang ◽  
Fengmao Chen ◽  
Lichao Wang ◽  
Lifeng Zhou ◽  
Juan Song

AbstractIn order to study the causes of pine wood nematode (PWN) departure from Monochamus alternatus, the effects of the feeding behavior of M. alternatus on the start date of the departure of PWN were studied. The start date of the departure of PWN carried by the directly fed M. alternatus was 5—13 d after beetle emergence, mainly concentrated within 6—10 d, with a mean (±SD) of 8.02 ± 1.96 d. The start date of the departure of PWN carried by the M. alternatus fed after starvation was 5—14 d after beetle emergence, mainly concentrated within 6—9 d, with a mean of 7.76 ± 2.28 d. The results show that there was no significant difference in the start departure date of PWN between the two treatments. This shows that the feeding behavior of M. alternatus is not the trigger for PWN departure. At the same time, it was found that the motility of the PWN carried by M. alternatus at 8 d after emergence was significantly greater than that of the PWN carried by the newly emerged M. alternatus. And the PWN carried by M. alternatus at 8 d after emergence was extracted more easily than the PWN carried by newly emerged beetles. These results show that greater motility was associated with easier departure of PWN from M. alternatus. In addition, transcriptome sequencing found that the level of oxidative phosphorylation metabolism of PWN carried by beetles at 8 d after emergence was significantly higher than that in the PWN carried by newly emerged beetle. High oxidative phosphorylation was associated with increased energy production and motility by the PWN and were the internal cause of the start of nematode departure.


2021 ◽  
Author(s):  
Ye Chen ◽  
Xiang Zhou ◽  
Kai Guo ◽  
Sha-Ni Chen ◽  
Xiu Su

Abstract Background: The pine wood nematode Bursaphelenchus xylophilus is a worldwide destructive pest on Pinus trees and lacks effective control measures. Screening nematotoxic protein toxins has been conducted to develop new strategies for nematode control. Results: The present study provided initial insights into the responses of B. xylophilus exposed to a nematocidal cytolytic-like protein (CytCo) based on the transcriptome profiling. A large set of differentially expressed genes (1266 DEGs) were found related to nematode development, reproduction, metabolism, motion, and immune system. In response to the toxic protein, B. xylophilus upregulated DEGs encoding cuticle collagens, transporters, and cytochrome P450. In addition, many DEGs related to cell death, lipid metabolism, major sperm proteins, proteinases/peptidases, phosphatases, kinases, virulence factors, and transthyretin-like proteins were downregulated. And Gene Ontology enrichment analysis showed that CytCo treatment significantly affecting DEGs functioning in muscle contraction, lipid localization, MAPK cascade. The pathway richness of Kyoto Encyclopedia of Genes and Genomes showed that the DEGs were concentrated in lysosome and fatty acid degradation. The weight co-expression network analysis indicated that the hub genes affected by CytCo were associated with the nematode cuticular collagen. Conclusions: These results showed that the CytCo protein toxin could interference gene expression to produce multiple nematotoxic effects, providing initial insight into its control potential of pine wood nematode.


Nematology ◽  
2004 ◽  
Vol 6 (2) ◽  
pp. 279-285 ◽  
Author(s):  
Jae Soon Kang ◽  
Kwang Sik Choi ◽  
Sang Chul Shin ◽  
Il Sung Moon ◽  
Sang Gil Lee ◽  
...  

Abstract Pine wood wilt disease caused by the pine wood nematode, Bursaphelenchus xylophilus , has been a serious problem in the southern regions of Korea. Efficient diagnosis of B. xylophilus from infected pine wood specimens is critical for the management of this pest. Traditional microscopic examination often results in an erroneous identification because a closely related non-pathogenic species, B. mucronatus, has a great degree of morphological similarity to B. xylophilus. In an attempt to search for reliable molecular markers for the discrimination of these species, we have cloned the 5S rRNA genomic DNA fragments containing both coding and intergenic spacer (IGS) regions from B. xylophilus and B. mucronatus through a homology-probing PCR strategy. Sequence analyses revealed that coding sequences of the 5S rRNA gene from the two species are almost identical (98.3% homology) but that the IGS sequences differ substantially between the species. Based on the IGS sequence differences (69.7% homology), we designed species-specific primer sets and developed a PCR-based diagnosis protocol for the identification and discrimination of the two nematode species on a molecular basis.


2020 ◽  
Author(s):  
Min‐Kyoung Kang ◽  
Min‐Hee Kim ◽  
Hae‐Ryong Park ◽  
Min‐Jiao Liu ◽  
Chun Zhi Jin ◽  
...  

2019 ◽  
Vol 31 (4) ◽  
pp. 1399-1403
Author(s):  
Sung-Chan Lee ◽  
Hyo-Rim Lee ◽  
Dong-Soo Kim ◽  
Jun-Hyeong Kwon ◽  
Min-Jung Huh ◽  
...  

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