scholarly journals Characterization of bacterial communities associated with the pine wilt disease insect vectors Monochamus alternatus Hope and host trees Pinus massoniana

2019 ◽  
Author(s):  
Yajie Guo ◽  
Qiannan Lin ◽  
lvyi Chen ◽  
Carballar-Lejarazú Rebeca ◽  
Ensi Shao ◽  
...  

Abstract Background Pine wilt disease (PWD) is a destructive disease caused by the pinewood nematode Bursaphelenchus xylophilus . Monochamus alternatus Hope is the main vector of this disease. The symbiotic microorganisms can play an important role in the transmission cycle mechanism. However, the role of bacterial microorganisms in the transmission of pine wood nematode by M. alternatus is not clear currently. The main purpose of this study is to reveal the composition and diversity of microbial flora in the gut of M. alternatus , as well as healthy and infected Pinus massoniana and its peripheral environment to discover the important microbial flora contributing to the transmission cycle.Methods In this study, total DNA was extracted from 60 samples, including 20 samples of M. alternatus gut from different larval instars, healthy P. massoniana , nematode-infected P. massoniana and their peripheral environment (needles, bark, phloem, xylem, root, surface soil and rhizosphere soil), by triplicate. Samples were used for 16S rDNA Amplicon sequencing to determine the composition and diversity of microbial flora in each sample.Results Infection of pinewood nematode resulted in an increase of the microbial community in the nematode-infected P. massoniana and its peripheral environment when compared with healthy P. massoniana , the microbial community in different tissues changed. Among them, Gryllotalpicola and Cellulomonas showed to be endemic microorganisms in nematode-infected P. massoniana , which can be used as indicators to detect the disease. Serratia was shown as an opportunistic pathogen, and was found to be enriched in M. alternatus gut and was also detected in the host plant tissues.Conclusions This study clarified the change of microbial community in the transmission of pine wilt disease by M. alternatus . An important theoretical basis for the prevention of pine wilt disease was structured by our research.

2020 ◽  
Author(s):  
Yajie Guo ◽  
Qiannan Lin ◽  
lvyi Chen ◽  
Carballar-Lejarazú Rebeca ◽  
Aishan Zhang ◽  
...  

Abstract Background Monochamus alternatus Hope is one of the insect vectors of pinewood nematode ( Bursaphelenchus xylophilus ), which causes the destructive pine wilt disease. The microorganisms within the ecosystem, comprising plants, their environment, and insect vectors, form complex networks. This study presents a systematic analysis of the bacterial microbiota in the M. alternatus midgut and its habitat niche. Methods Total DNA was extracted from 20 types of samples (with three replicates each) from M. alternatus and various tissues of healthy and infected P. massoniana (pines). 16S rDNA amplicon sequencing was conducted to determine the composition and diversity of the bacterial microbiota in each sample. Moreover, the relative abundances of bacteria in the midgut of M. alternatus larvae were verified by counting the colony-forming units. Results Pinewood nematode infection increased the microbial diversity in pines. Bradyrhizobium , Burkholderia , Dyella , Mycobacterium , and Mucilaginibacter were the dominant bacterial genera in the soil and infected pines. These results indicate that the bacterial community in infected pines may be associated with the soil microbiota. Interestingly, the abundance of the genus Gryllotalpicola was highest in the bark of infected pines. The genus Cellulomonas was not found in the midgut of M. alternatus , but it peaked in the phloem of infected pines, followed by the phloem of heathy pines. Moreover, the genus Serratia was not only present in the habitat niche, but it was also enriched in the M. alternatus midgut. The colony-forming unit assays showed that the relative abundance of Serratia sp. peaked in the midgut of instar II larvae (81%). Conclusions Overall, the results indicate that the bacterial microbiota in the soil and in infected pines are correlated. The Gryllotalpicola sp. and Cellulomonas sp. are potential microbial markers of pine wilt disease. Additionally, Serratia sp. could be an ideal agent for expressing insecticidal protein in the insect midgut by genetic engineering, which represents a new use of microbes to control M. alternatus .


2020 ◽  
Author(s):  
Yajie Guo ◽  
Qiannan Lin ◽  
lvyi Chen ◽  
Carballar-Lejarazú Rebeca ◽  
Aishan Zhang ◽  
...  

Abstract Background: Monochamus alternatus Hope is one of the insect vectors of pinewood nematode (Bursaphelenchus xylophilus), which causes the destructive pine wilt disease. The microorganisms within the ecosystem, comprising plants, their environment, and insect vectors, form complex networks. This study presents a systematic analysis of the bacterial microbiota in the M. alternatus midgut and its habitat niche.Methods: Total DNA was extracted from 20 types of samples (with three replicates each) from M. alternatus and various tissues of healthy and infected P. massoniana (pines). 16S rDNA amplicon sequencing was conducted to determine the composition and diversity of the bacterial microbiota in each sample. Moreover, the relative abundances of bacteria in the midgut of M. alternatus larvae were verified by counting the colony-forming units.Results: Pinewood nematode infection increased the microbial diversity in pines. Bradyrhizobium, Burkholderia, Dyella, Mycobacterium, and Mucilaginibacter were the dominant bacterial genera in the soil and infected pines. These results indicate that the bacterial community in infected pines may be associated with the soil microbiota. Interestingly, the abundance of the genus Gryllotalpicola was highest in the bark of infected pines. The genus Cellulomonas was not found in the midgut of M. alternatus, but it peaked in the phloem of infected pines, followed by the phloem of heathy pines. Moreover, the genus Serratia was not only present in the habitat niche, but it was also enriched in the M. alternatus midgut. The colony-forming unit assays showed that the relative abundance of Serratia sp. peaked in the midgut of instar II larvae (81%).Conclusions: Overall, the results indicate that the bacterial microbiota in the soil and in infected pines are correlated. The Gryllotalpicola sp. and Cellulomonas sp. are potential microbial markers of pine wilt disease. Additionally, Serratia sp. could be an ideal agent for expressing insecticidal protein in the insect midgut by genetic engineering, which represents a new use of microbes to control M. alternatus.


Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 731
Author(s):  
Zhuoqing Hao ◽  
Jixia Huang ◽  
Yantao Zhou ◽  
Guofei Fang

The Yangtze River Basin is among the river basins with the strongest strategic support and developmental power in China. As an invasive species, the pinewood nematode (PWN) Bursaphelenchus xylophilus has introduced a serious obstacle to the high-quality development of the economic and ecological synchronization of the Yangtze River Basin. This study analyses the occurrence and spread of pine wilt disease (PWD) with the aim of effectively managing and controlling the spread of PWD in the Yangtze River Basin. In this study, statistical data of PWD-affected areas in the Yangtze River Basin are used to analyse the occurrence and spread of PWD in the study area using spatiotemporal visualization analysis and spatiotemporal scanning statistics technology. From 2000 to 2018, PWD in the study area showed an “increasing-decreasing-increasing” trend, and PWD increased explosively in 2018. The spatial spread of PWD showed a “jumping propagation-multi-point outbreak-point to surface spread” pattern, moving west along the river. Important clusters were concentrated in the Jiangsu-Zhejiang area from 2000 to 2015, forming a cluster including Jiangsu and Zhejiang. Then, from 2015–2018, important clusters were concentrated in Chongqing. According to the spatiotemporal scanning results, PWD showed high aggregation in the four regions of Zhejiang, Chongqing, Hubei, and Jiangxi from 2000 to 2018. In the future, management systems for the prevention and treatment of PWD, including ecological restoration programs, will require more attention.


2021 ◽  
Vol 12 ◽  
Author(s):  
Honglong Chu ◽  
Haihua Wang ◽  
Yanan Zhang ◽  
Zhumei Li ◽  
Chunyan Wang ◽  
...  

Pine wilt disease (PWD) is a deadly disease to pines (Pinus spp.) worldwide. The occurrence of PWD can reduce the relative abundance of root ectomycorrhizal fungi (ECMF) and dark septate endophytes (DSE). However, the effects of exogenous ECMF/DSE inoculation on the rhizosphere microbial community structure of Pinus tabulaeformis infected by pine wood nematode (PWN) is little known. Here, we tested how ECMF/DSE may improve resistance to PWD by quantifying microbial carbon biomass and soil enzymatic activity among different treatments at 6 and 9 months after PWN infection. Denaturing gradient gel electrophoresis (DGGE) was used to study the microbial community structure at 3, 6, and 9 months after PWN infection in the rhizosphere of P. tabulaeformis seedlings inoculated with ECMF/DSE. The results showed that exogenous ECMF/DSE inoculation reduced the disease severity caused by PWN infection. After PWN infection, the rhizosphere microbial carbon of seedlings inoculated with Amanita vaginata, Suillus bovinus, Gaeumannomyces cylindrosporus, and Paraphoma chrysanthemicola was 38.16, 49.67, 42.11, and 96.05% higher than that of the control group, respectively. Inoculation of ECMF/DSE inhibited the decrease of rhizosphere microbial biomass caused by PWN infection. The richness and diversity of P. tabulaeformis rhizosphere fungi at 9 months were reduced by PWN infection but partially recovered by the exogenous fungi (ECMF/DSE) inoculation except for P. chrysanthemicola, which indicates a role of ECMF/DSE in maintaining stability of the microbial community. Inoculation with ECMF/DSE increased the beneficial bacterial (Thauera sp., Mesorhizobium sp., etc.) and fungal groups (Tomentella ellisii, Wilcoxina mikolae, etc.) of in the rhizosphere. In summary, exogenous ECMF/DSE inoculation could increase P. tabulaeformis resistance to PWD probably by improving the rhizosphere microenvironment.


2019 ◽  
Vol 49 (4) ◽  
pp. e12518 ◽  
Author(s):  
Rimi Yamaguchi ◽  
Koji Matsunaga ◽  
Tomonori Hirao ◽  
Miho Tamura ◽  
Atsushi Watanabe

Insects ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 376 ◽  
Author(s):  
Hongjian Chen ◽  
Dejun Hao ◽  
Zhiqiang Wei ◽  
Lujie Wang ◽  
Tao Lin

Monochamus alternatus is an important insect pest in pine forests of southern China and the dispersing vector of the pine wood nematode, Bursaphelenchus xylophilus, which leads to pine wilt disease (PWD). Microbiome of M. alternatus may contribute to survival of larvae in the host pine trees. In order to investigate the intestinal bacterial structure of M. alternatus during the larvae and pupae stages in host trees, and infer the function of symbiotic bacteria, we used 16S rRNA gene Illumina sequencing to obtain and compare the bacterial community composition in the foregut, midgut, and hindgut of larvae, pupal intestines, larval galleries, and pupal chambers of M. alternatus. The diversity of the bacterial community in larval intestines and pupal intestines were similar, as well as was significantly greater in larval galleries and pupal chambers. Although there were differences in bacterial compositions in different samples, similar components were also found. Proteobacteria and Firmicutes were the two most dominant phyla in all samples, and genera Enterobacter, Raoultella, Serratia, Lactococcus, and Pseudomonas were dominant in both the intestinal samples and plant tissue samples. Enterobacter was the most abundant genus in larval intestines, and Serratia was dominant in pupal intestine. The functions of these dominant and specific bacteria were also predicted through metagenomic analyses. These bacteria may help M. alternatus degrade cellulose and pinene. The specific role of symbiotic bacteria in the infection cycle of PWD also warrants further study in the future.


Nematology ◽  
2021 ◽  
pp. 1-17
Author(s):  
Wei Lu ◽  
Xiao-Jia Zhao ◽  
Jia-Jin Tan

Summary Pine wilt disease (PWD) is a devastating pine disease caused by Bursaphelenchus xylophilus and its main host in China is Pinus massoniana. The relationship between endophytic bacteria and disease resistance in P. massoniana remains unclear. In this paper, the leaves, roots, stems and treetops of different disease-resistant P. massoniana were studied as the research objective and Illumina MiSeq sequencing was used to analyse whether there were significant differences in the composition and diversity of endophytic bacterial communities between different disease-resistant P. massoniana. The results showed that at the genus level there were no obvious differences in the composition of the endophytic bacterial community of different disease-resistant P. massoniana in the leaves, but there were obvious differences in the roots, stems and treetops. The richness and diversity of endophytic bacteria in P. massoniana had no significant impact on its disease resistance, whilst the structure of endophytic bacterial community in stems and treetops may be related to its disease resistance.


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