Bursaphelenchus xylophilus: An Important Pathogenic Factor of Pine Wilt Disease and Its Relationship With Bursaphelenchus mucronatus

Plant Disease ◽  
2021 ◽  
Author(s):  
Yu-Long Li ◽  
Chang-Ji Fan ◽  
Xiao-Hui Jiang ◽  
Xing-Yi Tian ◽  
Zheng-Min Han

Pine wilt disease is the most devastating pine disease caused by Bursaphelenchus xylophilus. Bursaphelenchus mucronatus is morphologically similar to B. xylophilus and geographically overlaps in its distribution. Although interspecific hybridization of the two nematodes has been performed in vitro, the dynamic regularity of hybrid formation and its risk in forests has not been well evaluated. In this study, a hybrid of B. xylophilus and Bursaphelenchus mucronatus mucronatus was identified in the laboratory and fields by molecular markers. The heterozygosity of ITS-5.8S loci for identification was unstable in the hybrid population, and the allele inherited from B. m. mucronatus was lost over several generations. We also provided evidence that hybrids existed in some new epidemic areas, while old epidemic areas were usually dominated by B. xylophilus. Hybrids could be generated when B. m. mucronatus was invaded by B. xylophilus, and the pathogenicity of the hybrids was similar to that of B. xylophilus. These findings may improve the understanding of the natural hybridization between B. xylophilus and B. m. mucronatus and pathogenic variation in pine wilt disease, providing new insights for future studies on disease detection, transmission, and quarantine.

Planta ◽  
2015 ◽  
Vol 241 (6) ◽  
pp. 1325-1336 ◽  
Author(s):  
Jorge M. S. Faria ◽  
Inês Sena ◽  
Inês Vieira da Silva ◽  
Bruno Ribeiro ◽  
Pedro Barbosa ◽  
...  

Nematology ◽  
2014 ◽  
Vol 16 (2) ◽  
pp. 219-227 ◽  
Author(s):  
Si-Mi Liao ◽  
Satomi Kasuga ◽  
Katsumi Togashi

Bursaphelenchus xylophilus causes pine wilt disease in Pinus trees whereas B. mucronatus has no or little virulence to the trees. Interspecific crossing experiments conducted so far suggest reproductive interference between the two nematode species. Theory predicts that one of the two competing species populations quickly displaces the other through reproductive interference in a frequency-dependent manner. Thus, it is anticipated that B. mucronatus suppresses the virulence of B. xylophilus against pine trees when B. mucronatus heavily outnumber B. xylophilus. To determine the suppressive effects of B. mucronatus, the two nematode species were inoculated simultaneously on 30 3-year-old Pinus thunbergii seedlings at three combinations of different numbers, and B. xylophilus alone was inoculated on 30 other seedlings at the corresponding numbers in early August. Seedlings were observed at intervals of 4 or 6 weeks and two stem sections were sampled from each seedling to determine the density and species composition of nematode populations after death or in December. Inoculation of B. mucronatus significantly retarded the speed of foliage discolouration from 0.170 ± 0.024 week−1 to 0.061 ± 0.017 week−1 and significantly prolonged the survival time of seedlings. Bursaphelenchus mucronatus significantly reduced the nematode density from 1799.7 ± 305.0 to 521.0 ± 148.4 (g dried seedling stem)−1. Analysis of rDNA genotype showed 1846 B xylophilus, no B. mucronatus and one hybrid.


1988 ◽  
Vol 54 (5) ◽  
pp. 606-615 ◽  
Author(s):  
Keiko KURODA ◽  
Toshihiro YAMADA ◽  
Kazuhiko MINEO ◽  
Hirotada TAMURA

2019 ◽  
Vol 49 (6) ◽  
pp. e12564
Author(s):  
Marta Salgueiro Alves ◽  
Anabela Pereira ◽  
Cláudia Vicente ◽  
Manuel Mota ◽  
Isabel Henriques

Nematology ◽  
2006 ◽  
Vol 8 (6) ◽  
pp. 869-879 ◽  
Author(s):  
Kazuyoshi Futai ◽  
Natsumi Kanzaki ◽  
Yuko Takeuchi

AbstractPine wilt disease causes ecological and economic damage in Japanese pine forests in spite of intensive effort to protect them from the pine wood nematode, Bursaphelenchus xylophilus. Pine trees infected with B. xylophilus emit a characteristic bouquet of volatile compounds bioactive to the vector beetle of the nematode, Monochamus alternatus, and potentially affecting symptom development inside the trees. To investigate the qualitative and quantitative properties of volatile compounds in the field, we profiled the volatile emissions in two Japanese black pine stands, one naturally suffering from pine wilt disease and the other artificially inoculated with B. xylophilus. In both pine stands, the emission of some terpenoids from the infected trees such as (−)-α-pinene, began to increase in summer, overlapping the oviposition season of the vector beetle, but peaked in the summer and autumn. These data suggest that the beetles may not necessarily depend on the tremendous quantity of volatiles alone when they search for suitable trees on which to oviposit.


2012 ◽  
Vol 134 (3) ◽  
pp. 521-532 ◽  
Author(s):  
Xin-rong Wang ◽  
Xi Cheng ◽  
Ya-dong Li ◽  
Jin-ai Zhang ◽  
Zhi-fen Zhang ◽  
...  

Nematology ◽  
2011 ◽  
Vol 13 (6) ◽  
pp. 653-659 ◽  
Author(s):  
Katsumi Togashi ◽  
Hiroko Maezono ◽  
Koji Matsunaga ◽  
Satoshi Tamaki

AbstractTo determine the relationship between resistance to pine wilt disease and the inhibition of nematode systemic dispersal in Pinus densiflora, a suspension of 200 Bursaphelenchus xylophilus was placed on the upper cut end of 5-cm-long, living or boiled branch sections of 17 clones of pine that had different resistance levels. Significantly more nematodes passed through boiled sections than living sections during 24 h. Living branches of the resistant P. densiflora clone group significantly suppressed the dispersal of B. xylophilus compared with those of the susceptible group, suggesting that the inhibition of nematode systemic dispersal was involved in the resistance mechanism of selected disease-resistant pine clones. However, there was no significant correlation between the resistance class and the mean number of nematodes passing through live branch sections within the resistant clone group. The reason for the lack of correlation is discussed in relation with the resistance mechanism.


2019 ◽  
Vol 51 (10) ◽  
pp. 1071-1078
Author(s):  
Xin Huang ◽  
Longjiao Hu ◽  
Xiaoqin Wu

Abstract Pine wilt disease, caused by the pine wood nematode Bursaphelenchus xylophilus, leads to severe damage to pine forests in China. In our previous study, effectors secreted by this pathogen were shown to play roles in the different infection stages of pine wilt disease, and a series of candidate effectors were predicted by transcriptome sequencing. This study identified and characterized a novel effector, BxSapB3, which was among these candidate effectors. Agrobacterium-mediated transient expression was used to identify BxSapB3. BxSapB3 was secreted by B. xylophilus and found to be capable of inducing cell death in Nicotiana benthamiana. Quantitative real-time PCR (qRT-PCR) analysis revealed that BxSapB3 was upregulated in a highly virulent strain of B. xylophilus and expressed at lower levels in a weakly virulent strain at the early stages of infection. When BxSapB3 was silenced in B. xylophilus, the process of infection was delayed. These results indicate that BxSapB3 acts as an effector and contributes to virulence at the early stages of B. xylophilus infection.


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