The potato rot nematode(Ditylenchus destructor) is a very economically important nematode in agronomic and horticultural plants worldwide. In this study, 43 populations of D. destructor were collected from different h...The potato rot nematode(Ditylenchus destructor) is a very economically important nematode in agronomic and horticultural plants worldwide. In this study, 43 populations of D. destructor were collected from different hosts across China, including 37 populations from Chinese herbal medicine plants. Obtained sequences of ITS-rDNA and D2–D3of 28S-rDNA genes of D. destructor were compared and analyzed. Nine types of significant length variations in ITS sequences were observed among all populations. The differences in ITS1 length were mainly caused by the presence of repetitive elements with substantial base substitutions. Reconstructions of ITS1 secondary structures showed that the minisatellites formed a stem structure. Ten haplotypes were observed in all populations based on mutations and variations of helix H9. Among them, 3 known haplotypes(A–C) were found in 7 populations isolated from potato,sweet potato, and Codonopsis pilosula, and 7 unique haplotypes were found in other 36 populations collected from C. pilosula and Angelica sinensis compared with 7 haplotypes(A–G) according to Subbotin' system. These unique haplotypes were different from haplotypes A–G, and we named them as haplotypes H–N. The present results showed that a total of 14 haplotypes(A–N) of ITS-rDNA have been found in D. destructor. Phylogenetic analyses of ITSrDNA and D2–D3 showed that all populations of D. destructor were clustered into two major clades: one clade only containing haplotype A from sweet potato and the other containing haplotypes B–N from other plants. For further verification, PCR-ITS-RFLP profiles were conducted on 7 new haplotypes. Collectively, our study suggests that D. destructor populations on Chinese medicinal materials are very different from those on other hosts and this work provides a paradigm for relevant researches.展开更多
Globally, white clover(Trifolium repens L.) is commonly infected by plant viruses. It is grown at gardens, roadsides, and public areas as ornamental plants in northern China. Some leaves present disease symptoms tha...Globally, white clover(Trifolium repens L.) is commonly infected by plant viruses. It is grown at gardens, roadsides, and public areas as ornamental plants in northern China. Some leaves present disease symptoms that are similar to those of virus infection. However, to our knowledge, no records are available from China regarding white clover(Trifolium repens L.) virus co-infection. To determine the viral species that infect white clover in China, plant samples with virus disease symptoms were collected and virion morphology and ultrastructure morphology of co-infected plants were observed by electron microscopy; viruses were detected by enzyme linked immunosorbent assay(ELISA) and reverse transcription PCR(RT-PCR). Virus co-infection was studied by double antibody sandwich enzyme linked immunosorbent assay(DAS-ELISA) and real-time fluorescence quantitative PCR(RT-q PCR) after rub-inoculation of virus-free white clover planted in a growth chamber(25°C) with a photoperiod of 16 h, using single or several purified virions. Results showed that there were six types of symptoms, including those of shrinking mosaic, shrinking and macular mosaic, severe mottle mosaic, yellow macular mosaic, shrinkage chlorisis, and ring plaque and ring stria. The incidence rates for each symptom were 20.93, 1.48, 16.85, 59.07, 1.30, and 0.37%, respectively, based on the field investigation. Two types of viral pathogens were identified as Alfalfa mosaic virus(AMV) and White clover mosaic virus(WCMV). In mesophyll cells, virus particles with bacilliform virions formed aggregates and linear virions were bundle shaped. The detection rate of AMV was 100% in white clover samples by DAS-ELISA and RT-PCR detection, whereas that of WCMV was 83.33%. The co-infection rate was 83.33%. The relative contents of AMV and WCMV were significantly increased by 5.897-and 3.515-fold upon co-infection, when compared to that with single virus infection. We observed larger starch particles and fewer or collapsed chloroplast grana in co-infected plants; in addition, vacuoles were twisted and smaller, compared to those of healthy plants. To our knowledge, this is the first report of co-infection by AMV and WCMV in white clover, which has caused severe mosaicism and ultrastructure lesions in co-infected plants in China.展开更多
The cereal cyst nematode,Heterodera avenae,is one of the most economically important pathogens impacting the worldwide production of cereals and is widely distributed in more than 16 regions in China.The present study...The cereal cyst nematode,Heterodera avenae,is one of the most economically important pathogens impacting the worldwide production of cereals and is widely distributed in more than 16 regions in China.The present study used the numbers of nematodes inside the plant roots to evaluate the resistance/susceptibility of different subpopulations of barley Hordeum vulgare(QH2R,QH6R and TB2R)to H.avenae under field and pot conditions.Nematode development in two highly resistant varieties was also evaluated by in vivo experiment and microscopic observation.Analyses of 186selected varieties showed the numbers of susceptible varieties identified with the number of females/cysts per plant(NFP)method were significantly higher than those identified with the Pf/Pi ratio(PPR)method,which indicated that the NFP method rather than the PPR method is more reliable to evaluate the resistance of barley.The field and pot experiment results indicated that the QH2R subpopulation had lower females/cysts numbers than QH6R and TB2R subpopulations,and eight HR varieties(Sunong 7617,Sunong 7635,Dongyuan 87-14,Rudong 14-46,Rudong 87-57,Rudong 87-8-45,Rudong 88-14-2,and Rudong 88-67-1)were identified in QH2R,with the NFP numbers below 4.2.Further microscopic observation of nematode development suggested that H.avenae often penetrated less into highly resistant varieties(Sunong 7635 and Dongyuan 87-14)and more frequently failed to develop into females than the susceptible barleys.The promising resistant varieties identified in the present research might be helpful for breeders to develop CCN-resistant cultivars and control H.avenae populations effectively at low costs.展开更多
The Asian longhorn beetle (ALB) Anoplophora glabripennis is one of the most successful and most feared invasive insect species worldwide. This review covers recent research concerning the distribution of and damage ca...The Asian longhorn beetle (ALB) Anoplophora glabripennis is one of the most successful and most feared invasive insect species worldwide. This review covers recent research concerning the distribution of and damage caused by ALB, as well as major efforts to control and manage ALB in China. The distribution and destruction range of ALB have continued to expand over the past decade worldwide, and the number of interceptions has remained high. Detection and monitoring methods for the early discovery of ALB have diversified, with advances in semiochemical research and using satellite remote sensing in China. Ecological control of ALB in China involves planting mixtures of preferred and resistant tree species, and this practice can prevent outbreaks. In addition, strategies for chemical and biological control of ALB have achieved promising results during the last decade in China, especially the development of insecticides targeting different stages of ALB, and applying Dastarcus helophoroides and Dendrocopos major as biocontrol agents. Finally, we analyze recommendations for ALB prevention and management strategies based on native range and invasive area research. This information will hopefully help some invaded areas where the target is containment of ALB.展开更多
Identifying sources of phytopathogen inoculum and determining their contributions to disease outbreaks are essential for predicting disease development and establishing control strategies.Puccinia striiformis f.sp.tri...Identifying sources of phytopathogen inoculum and determining their contributions to disease outbreaks are essential for predicting disease development and establishing control strategies.Puccinia striiformis f.sp.tritici(Pst),the causal agent of wheat stripe rust,is an airborne fungal pathogen with rapid virulence variation that threatens wheat production through its long-distance migration.Because of wide variation in geographic features,climatic conditions,and wheat production systems,Pst sources and related dispersal routes in China are largely unclear.In the present study,we performed genomic analyses of 154 Pst isolates from all major wheat-growing regions in China to determine Pst population structure and diversity.Through trajectory tracking,historical migration studies,genetic introgression analyses,and field surveys,we investigated Pst sources and their contributions to wheat stripe rust epidemics.We identified Longnan,the Himalayan region,and the Guizhou Plateau,which contain the highest population genetic diversities,as the Pst sources in China.Pst from Longnan disseminates mainly to eastern Liupan Mountain,the Sichuan Basin,and eastern Qinghai;that from the Himalayan region spreads mainly to the Sichuan Basin and eastern Qinghai;and that from the Guizhou Plateau migrates mainly to the Sichuan Basin and the Central Plain.These findings improve our current understanding of wheat stripe rust epidemics in China and emphasize the need for managing stripe rust on a national scale.展开更多
基金supported by the National Natural Science Foundation of China (31760507)the National Key R&D Program of China (2018YFC1706301)。
文摘The potato rot nematode(Ditylenchus destructor) is a very economically important nematode in agronomic and horticultural plants worldwide. In this study, 43 populations of D. destructor were collected from different hosts across China, including 37 populations from Chinese herbal medicine plants. Obtained sequences of ITS-rDNA and D2–D3of 28S-rDNA genes of D. destructor were compared and analyzed. Nine types of significant length variations in ITS sequences were observed among all populations. The differences in ITS1 length were mainly caused by the presence of repetitive elements with substantial base substitutions. Reconstructions of ITS1 secondary structures showed that the minisatellites formed a stem structure. Ten haplotypes were observed in all populations based on mutations and variations of helix H9. Among them, 3 known haplotypes(A–C) were found in 7 populations isolated from potato,sweet potato, and Codonopsis pilosula, and 7 unique haplotypes were found in other 36 populations collected from C. pilosula and Angelica sinensis compared with 7 haplotypes(A–G) according to Subbotin' system. These unique haplotypes were different from haplotypes A–G, and we named them as haplotypes H–N. The present results showed that a total of 14 haplotypes(A–N) of ITS-rDNA have been found in D. destructor. Phylogenetic analyses of ITSrDNA and D2–D3 showed that all populations of D. destructor were clustered into two major clades: one clade only containing haplotype A from sweet potato and the other containing haplotypes B–N from other plants. For further verification, PCR-ITS-RFLP profiles were conducted on 7 new haplotypes. Collectively, our study suggests that D. destructor populations on Chinese medicinal materials are very different from those on other hosts and this work provides a paradigm for relevant researches.
基金financial support of the Key Laboratory of Grassland Ecosystem of Ministry of Education of China(CYZS-2011006)
文摘Globally, white clover(Trifolium repens L.) is commonly infected by plant viruses. It is grown at gardens, roadsides, and public areas as ornamental plants in northern China. Some leaves present disease symptoms that are similar to those of virus infection. However, to our knowledge, no records are available from China regarding white clover(Trifolium repens L.) virus co-infection. To determine the viral species that infect white clover in China, plant samples with virus disease symptoms were collected and virion morphology and ultrastructure morphology of co-infected plants were observed by electron microscopy; viruses were detected by enzyme linked immunosorbent assay(ELISA) and reverse transcription PCR(RT-PCR). Virus co-infection was studied by double antibody sandwich enzyme linked immunosorbent assay(DAS-ELISA) and real-time fluorescence quantitative PCR(RT-q PCR) after rub-inoculation of virus-free white clover planted in a growth chamber(25°C) with a photoperiod of 16 h, using single or several purified virions. Results showed that there were six types of symptoms, including those of shrinking mosaic, shrinking and macular mosaic, severe mottle mosaic, yellow macular mosaic, shrinkage chlorisis, and ring plaque and ring stria. The incidence rates for each symptom were 20.93, 1.48, 16.85, 59.07, 1.30, and 0.37%, respectively, based on the field investigation. Two types of viral pathogens were identified as Alfalfa mosaic virus(AMV) and White clover mosaic virus(WCMV). In mesophyll cells, virus particles with bacilliform virions formed aggregates and linear virions were bundle shaped. The detection rate of AMV was 100% in white clover samples by DAS-ELISA and RT-PCR detection, whereas that of WCMV was 83.33%. The co-infection rate was 83.33%. The relative contents of AMV and WCMV were significantly increased by 5.897-and 3.515-fold upon co-infection, when compared to that with single virus infection. We observed larger starch particles and fewer or collapsed chloroplast grana in co-infected plants; in addition, vacuoles were twisted and smaller, compared to those of healthy plants. To our knowledge, this is the first report of co-infection by AMV and WCMV in white clover, which has caused severe mosaicism and ultrastructure lesions in co-infected plants in China.
基金financially supported by the National Natural Science Foundation of China(31772142 and 31972248)the Special Fund for Agro-Scientific Research in the Public Interest,China(201503114)the National Key Research and Development Program,China(2018YFD0201202)。
文摘The cereal cyst nematode,Heterodera avenae,is one of the most economically important pathogens impacting the worldwide production of cereals and is widely distributed in more than 16 regions in China.The present study used the numbers of nematodes inside the plant roots to evaluate the resistance/susceptibility of different subpopulations of barley Hordeum vulgare(QH2R,QH6R and TB2R)to H.avenae under field and pot conditions.Nematode development in two highly resistant varieties was also evaluated by in vivo experiment and microscopic observation.Analyses of 186selected varieties showed the numbers of susceptible varieties identified with the number of females/cysts per plant(NFP)method were significantly higher than those identified with the Pf/Pi ratio(PPR)method,which indicated that the NFP method rather than the PPR method is more reliable to evaluate the resistance of barley.The field and pot experiment results indicated that the QH2R subpopulation had lower females/cysts numbers than QH6R and TB2R subpopulations,and eight HR varieties(Sunong 7617,Sunong 7635,Dongyuan 87-14,Rudong 14-46,Rudong 87-57,Rudong 87-8-45,Rudong 88-14-2,and Rudong 88-67-1)were identified in QH2R,with the NFP numbers below 4.2.Further microscopic observation of nematode development suggested that H.avenae often penetrated less into highly resistant varieties(Sunong 7635 and Dongyuan 87-14)and more frequently failed to develop into females than the susceptible barleys.The promising resistant varieties identified in the present research might be helpful for breeders to develop CCN-resistant cultivars and control H.avenae populations effectively at low costs.
基金supported by the Chinese National Natural Science Foundation(32160379)the Fundamental Research Funds for the Central Universities(BFUKF202104)+1 种基金the Gansu Provincial Natural Science Foundation(20JR10R526)the Fuxi young talents training program of Gansu Agricultural University(Gaufx-04Y08).
文摘The Asian longhorn beetle (ALB) Anoplophora glabripennis is one of the most successful and most feared invasive insect species worldwide. This review covers recent research concerning the distribution of and damage caused by ALB, as well as major efforts to control and manage ALB in China. The distribution and destruction range of ALB have continued to expand over the past decade worldwide, and the number of interceptions has remained high. Detection and monitoring methods for the early discovery of ALB have diversified, with advances in semiochemical research and using satellite remote sensing in China. Ecological control of ALB in China involves planting mixtures of preferred and resistant tree species, and this practice can prevent outbreaks. In addition, strategies for chemical and biological control of ALB have achieved promising results during the last decade in China, especially the development of insecticides targeting different stages of ALB, and applying Dastarcus helophoroides and Dendrocopos major as biocontrol agents. Finally, we analyze recommendations for ALB prevention and management strategies based on native range and invasive area research. This information will hopefully help some invaded areas where the target is containment of ALB.
基金supported by the National Key Research and Development Program of China to X.H.and Y.L.(2021YFD1401000)the National Natural Science Foundation of China(31471731 and 31772102)to X.H.the Postdoctoral Science Foundation of China to Y.L.(2021M690130).
文摘Identifying sources of phytopathogen inoculum and determining their contributions to disease outbreaks are essential for predicting disease development and establishing control strategies.Puccinia striiformis f.sp.tritici(Pst),the causal agent of wheat stripe rust,is an airborne fungal pathogen with rapid virulence variation that threatens wheat production through its long-distance migration.Because of wide variation in geographic features,climatic conditions,and wheat production systems,Pst sources and related dispersal routes in China are largely unclear.In the present study,we performed genomic analyses of 154 Pst isolates from all major wheat-growing regions in China to determine Pst population structure and diversity.Through trajectory tracking,historical migration studies,genetic introgression analyses,and field surveys,we investigated Pst sources and their contributions to wheat stripe rust epidemics.We identified Longnan,the Himalayan region,and the Guizhou Plateau,which contain the highest population genetic diversities,as the Pst sources in China.Pst from Longnan disseminates mainly to eastern Liupan Mountain,the Sichuan Basin,and eastern Qinghai;that from the Himalayan region spreads mainly to the Sichuan Basin and eastern Qinghai;and that from the Guizhou Plateau migrates mainly to the Sichuan Basin and the Central Plain.These findings improve our current understanding of wheat stripe rust epidemics in China and emphasize the need for managing stripe rust on a national scale.