scholarly journals Nematicidal activities of aureothin and alloaureothin from endophytic bacteria, Streptomyces sp. AE170020, against the pine wood nematode, Bursaphelenchus xylophilus

Author(s):  
Min-Kyoung Kang ◽  
Jong-Hoon Kim ◽  
Min-Jiao Liu ◽  
Chun-Zhi Jin ◽  
Dong-Jin Park ◽  
...  

Abstract Endophytic bacteria, a rich source of bioactive secondary metabolites, are ideal candidates for environmentally benign agents. In this study, an endophytic strain, Streptomyces sp. AE170020, was isolated and selected for the purification of nematicidal substances based on its high nematicidal activity. Two highly active components, aureothin and alloaureothin, were identified, and their chemical structures were determined using spectroscopic analysis. Both compounds suppressed the growth, reproduction, and behavior of Bursaphelenchus xylophilus. In in vivo experiments, the extracts of strain Streptomyces sp. AE170020 effectively suppressed the development of pine wilt disease in four-year-old plants of Pinus densiflora. The potency of secondary metabolites isolated from endophytic strains suggests applications in controlling Bursaphelenchus xylophilus and opens an avenue for further research on exploring bioactive substances against the pine wood nematode.

Nematology ◽  
2007 ◽  
Vol 9 (5) ◽  
pp. 663-670 ◽  
Author(s):  
Li Lin Zhao ◽  
Wei Wei ◽  
Xing Yao Zhang ◽  
David Kulhavy ◽  
Jiang Hua Sun

AbstractThe third-stage dispersal juvenile (JIII) is the stage for survival and dispersal in the winter of the pine wood nematode, Bursaphelenchus xylophilus. Through investigations at different temperatures, we found two kinds of growth-arrested development, including the adult longevity extension and JIII formation induced by low temperature. They showed similar characters: densely packed lipid droplets and extended longevity. We considered that there were four stages in the formation of growth-arrested stages: induction, growth-arrested pathway, growth-arrested development and cold-tolerance duration. Moreover, at 4°C there were significant changes in secondary metabolites, which may be related to signal communication and metabolism associated with the formation of growth-arrested stages. The results suggested that low temperature was necessary for the dispersal of pine wood nematode and influenced distribution and intensity of pine wilt.


Nematology ◽  
2015 ◽  
Vol 17 (5) ◽  
pp. 581-589 ◽  
Author(s):  
Xiao-Jing Tian ◽  
Xiao-Qin Wu ◽  
Yang Xiang ◽  
Xin Fang ◽  
Jian-Ren Ye

Pine wilt disease (PWD) caused by the pine wood nematode (PWN), Bursaphelenchus xylophilus, is a destructive forest disease. Recent studies showed that bacteria associated with PWN might play important roles in PWD. In this study, the effects of endobacteria isolated from PWN on the development and virulence of PWN were evaluated. The results revealed that endobacteria isolated from high virulence PWN could partially promote the development of the nematode, while endobacteria from PWN with low virulence could inhibit the development of nematode. Both bacteria-free and non-sterilised nematodes were able to infect microcuttings of Pinus densiflora. The endobacterial isolates, Stenotrophomonas maltophilia NSBx.14 and Achromobacter xylosoxidans ssp. xylosoxidans NSBx.22, enhanced the virulence of low virulence PWN but reduced the virulence of high virulence PWN. The results suggest the pathogenicity of PWN is not affected by loss of bacteria and endobacteria might play a role in the development and virulence of PWN.


Nematology ◽  
2011 ◽  
Vol 13 (5) ◽  
pp. 521-528 ◽  
Author(s):  
Quang Le Dang ◽  
Seung Wan Son ◽  
Hyang-Mi Cheon ◽  
Gyung Ja Choi ◽  
Yong Ho Choi ◽  
...  

Abstract Pine wilt disease is a very complex disease known to be caused by the pine wood nematode, Bursaphelenchus xylophilus, and its accompanying bacteria. The phytotoxin-producing bacteria have been reported to be involved in the development of pine wilt disease. In this study, we attempted to characterise phytotoxins produced by Burkholderia arboris KRICT1, which was carried by the pine wood nematode. It produced phytotoxic compounds in the pine seedling assay, and the ethyl acetate (EtOAc) layer of the fermentation broth of the strain displayed phytotoxic activity on the pine callus of Pinus densiflora. One active compound was isolated from the EtOAc layer by repeated Sephadex LH-20 column chromatography and preparative TLC. Using mainly mass spectroscopy and nuclear magnetic resonance (NMR) spectroscopy, the chemical structure was determined to be that of pyochelin (a mixture of two interconvertible diastereoisomers, pyochelin I and II). Pyochelin exposure reduced the viability of pine callus. Compared with phenylacetic acid, a phytotoxin produced by Bacillus spp. that was transmitted by B. xylophilus in Japan, pyochelin showed much stronger phytotoxicity. The results suggested that pyochelin might play a role in the wilting process of pine wilt disease.


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.


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