Several economically relevant phytoplasma-associated diseases are described together with an update of phytoplasma taxonomy and major biological and molecular features of phytoplasmas. Outlook about persepectives and ...Several economically relevant phytoplasma-associated diseases are described together with an update of phytoplasma taxonomy and major biological and molecular features of phytoplasmas. Outlook about persepectives and future work to contain spread of these diseases are also reported.展开更多
In the last decade,some disease occurred on our experimental farms that had caused serious losses.They were not caused by fungi,bacteria or viruses.By loop-mediated isothermal amplification(LAMP)technique,the detectio...In the last decade,some disease occurred on our experimental farms that had caused serious losses.They were not caused by fungi,bacteria or viruses.By loop-mediated isothermal amplification(LAMP)technique,the detection results pointed to the possible pathogen as phytoplasma.The investigation results implied that phytoplasmas could cause more than 13 kinds of symptoms in almost all parts of plants in B.napus L.,including witches’broom,multi-stems,aggregate main inflorescences,and flat stems.The incidences of these phytoplasma-associated diseases in our experimental farms rose from 1.61%in 2010 to 6.00%in 2021.Some phytoplasma infected plants died without any growing points.These studies would be helpful for detecting phytoplasmas diseases,selecting disease resistant germplasm and improving varieties with disease resistances in B.napus L.展开更多
Jujube witches’broom(JWB)caused by phytoplasma has a severely negative effect on multiple metabolisms in jujube.The GST gene family in plants participates in the regulation of a variety of biotic and abiotic stresses...Jujube witches’broom(JWB)caused by phytoplasma has a severely negative effect on multiple metabolisms in jujube.The GST gene family in plants participates in the regulation of a variety of biotic and abiotic stresses.This study aims to identify and reveal the changes in the jujube GST gene family in response to phytoplasma infection.Here,70 ZjGSTs were identified in the jujube genome and divided into 8 classes.Among them,the Tau-class,including 44 genes,was the largest.Phylogenetic analysis indicated that Tau-class genes were highly conserved among species,such as Arabidopsis,cotton,chickpea,and rice.Through chromosome location analysis,37.1%of genes were clustered,and 8 of 9 gene clusters were composed of Tau class members.Through RT-PCR,qRT-PCR and enzyme activity detection,the results showed that the expression of half(20/40)of the tested ZjGSTs was inhibited by phytoplasma infection in field and tissue culture conditions,and GST activity was also significantly reduced.In the resistant and susceptible varieties under phytoplasma infection,ZjGSTU49-ZjGSTU54 in the cluster IV showed opposite expression patterns,which may be due to functional divergence during evolution.Some upregulated genes(ZjGSTU45,ZjGSTU49,ZjGSTU59,and ZjGSTU70)might be involved in the process of jujube against JWB.The yeast two-hybrid results showed that all 6 Tauclass proteins tested could form homodimers or heterodimers.Overall,the comprehensive analysis of the jujube GST gene family revealed that ZjGSTs responded actively to phytoplasma infection.Furthermore,some screened genes(ZjGSTU24,ZjGSTU49-52,ZjGSTU70,and ZjDHAR10)will contribute to further functional studies of jujube-phytoplasma interactions.展开更多
The production of acid lime (Citrus aurantifolia) has declined in many parts of the world due to phytoplasmal infection by “Candidatus Phytoplasma aurantifolia”. The resulting Witches’ Broom Disease of Lime (WBDL) ...The production of acid lime (Citrus aurantifolia) has declined in many parts of the world due to phytoplasmal infection by “Candidatus Phytoplasma aurantifolia”. The resulting Witches’ Broom Disease of Lime (WBDL) causes stem and leaf proliferation and clustering that starts on a few branches and continues to spread until trees are killed within 5-7 years. Recent studies have shown that Phytoplasma alters the chemical composition of leaves. Leaves from WBDL-symptomatic lime trees were collected to determine their volatile compound composition. Phytoplasmal infection was confirmed by a polymerase chain reaction (PCR) assay using primers P1/P7 and R16F2n/R16R2 in direct and nested PCR, respectively. Restriction fragment length polymorphism (RFLP) profiles of acid lime Phytoplasma were identical with those of WBDL Phytoplasma. The phytochemical composition of symptomatic (infected) and asymptomatic (healthy) leaves of acid lime were determined using GC-MS analysis of steam distilled extract. The WBDL-symptomatic leaves had higher concentration in ?-limonene, β-ocimene and trans-caryophyllene and a reduction in other compounds (i.e. citral, citronellal, cisverbenol, neryl acetate, and linalool). Variations in the leaf phytochemical concentration indicate a possible role in the development of the WBDL disease symptoms.展开更多
A novel phytoplasma was detected in a cherry plum(Prunus cerasifera Ehrh) tree that mainly showed yellow leaf symptom. The tree was growing in an orchard located in Yangling District, Shaanxi Province, China. The le...A novel phytoplasma was detected in a cherry plum(Prunus cerasifera Ehrh) tree that mainly showed yellow leaf symptom. The tree was growing in an orchard located in Yangling District, Shaanxi Province, China. The leaves started as chlorotic and yellowing along leaf minor veins and leaf tips. Chlorosis rapidly developed to inter-veinal areas with the whole leaf becoming pale yellow in about 1-4 wk. Large numbers of phytoplasma-like bodies(PLBs) were seen under transmission electron microscopy. The majority of the PLBs was spherical or elliptical vesicles, with diameters in range of 0.1-0.6 μm, and distributed in the phloem cells of the infected tissues. A 1 246-bp 16 S ribosomal RNA(rRNA) gene fragment was amplified from DNA samples extracted from the yellow leaf tissues using two phytoplasma universal primer pairs R16mF2/R16mR1 and R16F2n/R16R2. Phylogenetic analysis using the 16 S rRNA gene sequence suggested that the phytoplasma associated with the yellow leaf symptoms belongs to a novel subclade in the aster yellows(AY) group(16SrI group). Virtual and actual restriction fragment length polymorphism(RFLP) analysis of the 16 S rRNA gene fragment revealed that the phytoplasma was distinguishable from all existing 19 subgroups in the AY group(16SrI) by four restriction sites, Hinf I, Mse I, Sau3 A I and Taq I. The similarity coefficients of comparing the RFLP pattern of the 16 S rRNA gene fragment of this phytoplasma to each of the 19 reported subgroups ranged from 0.73 to 0.87, which indicates the phytoplasma associated with the cherry plum yellow leaf(CPYL) symptoms is probably a distinct and novel subgroup lineage in the AY group(16SrI). In addition, the novel phytoplasma was experimentally transmitted to periwinkle(Catharanthus roseus) plants from the tree with CPYL symptoms and then back to a healthy 1-yr-old cherry plum tree via dodder(Cuscuta odorata) connections.展开更多
In recent years, a disease has been reported to affect peach trees in Kurdistan province of Iran causing serious losses to the production. Main symptoms of disease include leaf stunting and yellowing, which lead to fa...In recent years, a disease has been reported to affect peach trees in Kurdistan province of Iran causing serious losses to the production. Main symptoms of disease include leaf stunting and yellowing, which lead to failure in fruit production at harvest. For diagnosis of disease and identification of the causal agent, symptomatic leaf samples were collected in Kurdistan orchards during summer 2010 and were carried to the laboratory. Total DNA was extracted from plant samples according to the standard procedures and indexed by grafting and nested PCR using phytoplasma generic primers, P1/P7 and R16F2n/R2. PCR products were characterized by RFLP technique and direct sequencing. The 16S rDNA sequences were compared with those of other phytoplasmas in GenBank. Phytoplasma rDNA was amplified from 20 out 35 samples. The 16S rDNA sequences of the phytoplasma were identified in Peach samples which showed 98% similarity to that of “Candidatus Phytoplasma phoenicium” which is considered to be the causal agent of Almond witches’ broom. Phylogenetic analysis of 16S rDNA sequences placed peach strains in Almond witches broom isolate as a member of pigeon pea witches broom (PPWB) group. Further studies on the epidemiology of “Ca. Phytoplasma phoenicium” and its vector(s) in Iran are recommended in order to identify new natural hosts and develop successful disease management programs.展开更多
Paulownias are among the fastest growing trees in the world,but they often suffer tremendous loss of wood production due to infection by Paulownia witches'broom(PaWB)phytoplasmas.In this study,we have sequenced an...Paulownias are among the fastest growing trees in the world,but they often suffer tremendous loss of wood production due to infection by Paulownia witches'broom(PaWB)phytoplasmas.In this study,we have sequenced and assembled a high-quality nuclear genome of Paulownia fortunei,a commonly cultivated paulownia species.The assembled genome of P.fortunei is 511.6 Mb in size,with 93.2%of its sequences anchored to 20 pseudo-chromosomes,and it contains 31985 protein-coding genes.Phylogenomic analyses show that the family Paulowniaceae is sister to a clade composed of Phrymaceae and Orobanchaceae.Higher photosynthetic efficiency is achieved by integrating C3 photosynthesis and the crassulacean acid metabolism pathway,which may contribute to the extremely fast growth habit of paulownia trees.Comparative transcriptome analyses reveal modules related to cambial growth and development,photosynthesis,and defense responses.Additional genome sequencing of PaWB phytoplasma,combined with functional analyses,indicates that the effector PaWB-SAP54 interacts directly with Paulownia PfSPLa,which in turn causes the degradation of PfSPLa by the ubiquitin-mediated pathway and leads to the formation of witches'broom.Taken together,these results provide significant insights into the biology of paulownias and the regulatory mechanism for the formation of PaWB.展开更多
Stem segments from diseased Paulownia tomentosaXP, fortunei and leaves from healthy control were transformed with the expression vector p438PRSI via Agrobacterium tumefaciens. The p438PRSI vector contained shiva-1 gen...Stem segments from diseased Paulownia tomentosaXP, fortunei and leaves from healthy control were transformed with the expression vector p438PRSI via Agrobacterium tumefaciens. The p438PRSI vector contained shiva-1 gene, which encodes an antibacterial peptide under the control of a CaMV35S promoter. The regenerated plants from transformed explants were planted in a greenhouse and nursery. PCR and Southern blotting analysis showed that the shiva-1 gene was successfully integrated into the Paulownia genome. Transcription of the integrated shiva-1 gene was confirmed by RT-PCR. Bioassay in the green house and phytoplasma DNA-dot blotting demonstrated that resistance to Paulownia witch's broom disease (PWB) increased significantly in shiva-l-transgenic Paulownia. Further investigations indicated that higher Shiva- 1 expression correlated with fewer phytoplasma and less symptoms in diseased transgenic Paulownia. Together, our findings strongly suggest that breeding shiva-1-Paulownia is an effective strategy to control PWB disease.展开更多
The recent emergence ofseveralplant diseases caused by psyllid-borne bacterial pathogens worldwide (Candidatus Liberibaeter spp.) has created renewed interest on the interaction between psyllids and bacteria. In spi...The recent emergence ofseveralplant diseases caused by psyllid-borne bacterial pathogens worldwide (Candidatus Liberibaeter spp.) has created renewed interest on the interaction between psyllids and bacteria. In spite of these efforts to understand psyllid association with bacteria, many aspects of their interactions remain poorly understood. As more organisms are studied, subtleties on the molecular interactions as well as on the effects of the bacteria on the psyllid host are being uncovered. Additionally, psyllid-borne bacterial phytopathogens can also affect the host plant, which in turn can impact psyllid physiology and behavior. Here, we review the current literature on different aspects of the influence of bacteria on multitrophic interactions among plants, psyllids, and pathogens. We then highlight gaps that need to be addressed to advance this field, which can have significant implications for controlling these newly emergent and other plant diseases.展开更多
Vector-borne plant diseases have significant ecological and economic impacts,affecting farm profitability and forest composition throughout the world.Bacterial vector-borne pathogens have evolved sophisticated strateg...Vector-borne plant diseases have significant ecological and economic impacts,affecting farm profitability and forest composition throughout the world.Bacterial vector-borne pathogens have evolved sophisticated strategies to interact with their hemipteran insect vectors and plant hosts.These pathogens reside in plant vascular tissue,and their study represents an excellent opportunity to uncover novel biological mechanisms regulating intracellular pathogenesis and to contribute to the control of some of the world's most invasive emerging diseases.In this perspective,we highlight recent advances and major unanswered questions in the realm of bacterial vector-borne disease,focusing on liberibacters,phytoplasmas,spiroplasmas,and Xylella fastidiosa.展开更多
文摘Several economically relevant phytoplasma-associated diseases are described together with an update of phytoplasma taxonomy and major biological and molecular features of phytoplasmas. Outlook about persepectives and future work to contain spread of these diseases are also reported.
基金the financial support provided by project of Science and Technology Tackling Key Problems in Henan Province(Grant No.182102110430)the National Key Research and Development Program of China(Grant No.2016YFD0101300)by China Agricultural Research system(CARS-12).
文摘In the last decade,some disease occurred on our experimental farms that had caused serious losses.They were not caused by fungi,bacteria or viruses.By loop-mediated isothermal amplification(LAMP)technique,the detection results pointed to the possible pathogen as phytoplasma.The investigation results implied that phytoplasmas could cause more than 13 kinds of symptoms in almost all parts of plants in B.napus L.,including witches’broom,multi-stems,aggregate main inflorescences,and flat stems.The incidences of these phytoplasma-associated diseases in our experimental farms rose from 1.61%in 2010 to 6.00%in 2021.Some phytoplasma infected plants died without any growing points.These studies would be helpful for detecting phytoplasmas diseases,selecting disease resistant germplasm and improving varieties with disease resistances in B.napus L.
基金supported by grants from the National Key R&D Program Project Funding(Grant No.2018YFD1000607)the Foundation for 100 Innovative Talents of Hebei Province(Grant No.SLRC2019031)+1 种基金the National Natural Science Foundation of China(Grant No.31772285)the Hebei Province Innovation Foundation for Postgraduates(Grant No.CXZZBS2020097)。
文摘Jujube witches’broom(JWB)caused by phytoplasma has a severely negative effect on multiple metabolisms in jujube.The GST gene family in plants participates in the regulation of a variety of biotic and abiotic stresses.This study aims to identify and reveal the changes in the jujube GST gene family in response to phytoplasma infection.Here,70 ZjGSTs were identified in the jujube genome and divided into 8 classes.Among them,the Tau-class,including 44 genes,was the largest.Phylogenetic analysis indicated that Tau-class genes were highly conserved among species,such as Arabidopsis,cotton,chickpea,and rice.Through chromosome location analysis,37.1%of genes were clustered,and 8 of 9 gene clusters were composed of Tau class members.Through RT-PCR,qRT-PCR and enzyme activity detection,the results showed that the expression of half(20/40)of the tested ZjGSTs was inhibited by phytoplasma infection in field and tissue culture conditions,and GST activity was also significantly reduced.In the resistant and susceptible varieties under phytoplasma infection,ZjGSTU49-ZjGSTU54 in the cluster IV showed opposite expression patterns,which may be due to functional divergence during evolution.Some upregulated genes(ZjGSTU45,ZjGSTU49,ZjGSTU59,and ZjGSTU70)might be involved in the process of jujube against JWB.The yeast two-hybrid results showed that all 6 Tauclass proteins tested could form homodimers or heterodimers.Overall,the comprehensive analysis of the jujube GST gene family revealed that ZjGSTs responded actively to phytoplasma infection.Furthermore,some screened genes(ZjGSTU24,ZjGSTU49-52,ZjGSTU70,and ZjDHAR10)will contribute to further functional studies of jujube-phytoplasma interactions.
文摘The production of acid lime (Citrus aurantifolia) has declined in many parts of the world due to phytoplasmal infection by “Candidatus Phytoplasma aurantifolia”. The resulting Witches’ Broom Disease of Lime (WBDL) causes stem and leaf proliferation and clustering that starts on a few branches and continues to spread until trees are killed within 5-7 years. Recent studies have shown that Phytoplasma alters the chemical composition of leaves. Leaves from WBDL-symptomatic lime trees were collected to determine their volatile compound composition. Phytoplasmal infection was confirmed by a polymerase chain reaction (PCR) assay using primers P1/P7 and R16F2n/R16R2 in direct and nested PCR, respectively. Restriction fragment length polymorphism (RFLP) profiles of acid lime Phytoplasma were identical with those of WBDL Phytoplasma. The phytochemical composition of symptomatic (infected) and asymptomatic (healthy) leaves of acid lime were determined using GC-MS analysis of steam distilled extract. The WBDL-symptomatic leaves had higher concentration in ?-limonene, β-ocimene and trans-caryophyllene and a reduction in other compounds (i.e. citral, citronellal, cisverbenol, neryl acetate, and linalool). Variations in the leaf phytochemical concentration indicate a possible role in the development of the WBDL disease symptoms.
基金supported by the 111 Project from the Ministry of Education of China (B07049)the PhD Program Foundation from the Ministry of Education of China (20100204110004)the National Natural Science Foundation of China (31371913)
文摘A novel phytoplasma was detected in a cherry plum(Prunus cerasifera Ehrh) tree that mainly showed yellow leaf symptom. The tree was growing in an orchard located in Yangling District, Shaanxi Province, China. The leaves started as chlorotic and yellowing along leaf minor veins and leaf tips. Chlorosis rapidly developed to inter-veinal areas with the whole leaf becoming pale yellow in about 1-4 wk. Large numbers of phytoplasma-like bodies(PLBs) were seen under transmission electron microscopy. The majority of the PLBs was spherical or elliptical vesicles, with diameters in range of 0.1-0.6 μm, and distributed in the phloem cells of the infected tissues. A 1 246-bp 16 S ribosomal RNA(rRNA) gene fragment was amplified from DNA samples extracted from the yellow leaf tissues using two phytoplasma universal primer pairs R16mF2/R16mR1 and R16F2n/R16R2. Phylogenetic analysis using the 16 S rRNA gene sequence suggested that the phytoplasma associated with the yellow leaf symptoms belongs to a novel subclade in the aster yellows(AY) group(16SrI group). Virtual and actual restriction fragment length polymorphism(RFLP) analysis of the 16 S rRNA gene fragment revealed that the phytoplasma was distinguishable from all existing 19 subgroups in the AY group(16SrI) by four restriction sites, Hinf I, Mse I, Sau3 A I and Taq I. The similarity coefficients of comparing the RFLP pattern of the 16 S rRNA gene fragment of this phytoplasma to each of the 19 reported subgroups ranged from 0.73 to 0.87, which indicates the phytoplasma associated with the cherry plum yellow leaf(CPYL) symptoms is probably a distinct and novel subgroup lineage in the AY group(16SrI). In addition, the novel phytoplasma was experimentally transmitted to periwinkle(Catharanthus roseus) plants from the tree with CPYL symptoms and then back to a healthy 1-yr-old cherry plum tree via dodder(Cuscuta odorata) connections.
文摘In recent years, a disease has been reported to affect peach trees in Kurdistan province of Iran causing serious losses to the production. Main symptoms of disease include leaf stunting and yellowing, which lead to failure in fruit production at harvest. For diagnosis of disease and identification of the causal agent, symptomatic leaf samples were collected in Kurdistan orchards during summer 2010 and were carried to the laboratory. Total DNA was extracted from plant samples according to the standard procedures and indexed by grafting and nested PCR using phytoplasma generic primers, P1/P7 and R16F2n/R2. PCR products were characterized by RFLP technique and direct sequencing. The 16S rDNA sequences were compared with those of other phytoplasmas in GenBank. Phytoplasma rDNA was amplified from 20 out 35 samples. The 16S rDNA sequences of the phytoplasma were identified in Peach samples which showed 98% similarity to that of “Candidatus Phytoplasma phoenicium” which is considered to be the causal agent of Almond witches’ broom. Phylogenetic analysis of 16S rDNA sequences placed peach strains in Almond witches broom isolate as a member of pigeon pea witches broom (PPWB) group. Further studies on the epidemiology of “Ca. Phytoplasma phoenicium” and its vector(s) in Iran are recommended in order to identify new natural hosts and develop successful disease management programs.
基金This study was funded by the Key Cultivation Subjects Fund of Henan Province(grant 2011[339])the Academic Scientist Fund for Zhongyuan Scholars of Henan Province(grant 2018[99]).
文摘Paulownias are among the fastest growing trees in the world,but they often suffer tremendous loss of wood production due to infection by Paulownia witches'broom(PaWB)phytoplasmas.In this study,we have sequenced and assembled a high-quality nuclear genome of Paulownia fortunei,a commonly cultivated paulownia species.The assembled genome of P.fortunei is 511.6 Mb in size,with 93.2%of its sequences anchored to 20 pseudo-chromosomes,and it contains 31985 protein-coding genes.Phylogenomic analyses show that the family Paulowniaceae is sister to a clade composed of Phrymaceae and Orobanchaceae.Higher photosynthetic efficiency is achieved by integrating C3 photosynthesis and the crassulacean acid metabolism pathway,which may contribute to the extremely fast growth habit of paulownia trees.Comparative transcriptome analyses reveal modules related to cambial growth and development,photosynthesis,and defense responses.Additional genome sequencing of PaWB phytoplasma,combined with functional analyses,indicates that the effector PaWB-SAP54 interacts directly with Paulownia PfSPLa,which in turn causes the degradation of PfSPLa by the ubiquitin-mediated pathway and leads to the formation of witches'broom.Taken together,these results provide significant insights into the biology of paulownias and the regulatory mechanism for the formation of PaWB.
基金the National Natural Science Foundation of China,the President Foundation of the Chinese Academy of Sciences
文摘Stem segments from diseased Paulownia tomentosaXP, fortunei and leaves from healthy control were transformed with the expression vector p438PRSI via Agrobacterium tumefaciens. The p438PRSI vector contained shiva-1 gene, which encodes an antibacterial peptide under the control of a CaMV35S promoter. The regenerated plants from transformed explants were planted in a greenhouse and nursery. PCR and Southern blotting analysis showed that the shiva-1 gene was successfully integrated into the Paulownia genome. Transcription of the integrated shiva-1 gene was confirmed by RT-PCR. Bioassay in the green house and phytoplasma DNA-dot blotting demonstrated that resistance to Paulownia witch's broom disease (PWB) increased significantly in shiva-l-transgenic Paulownia. Further investigations indicated that higher Shiva- 1 expression correlated with fewer phytoplasma and less symptoms in diseased transgenic Paulownia. Together, our findings strongly suggest that breeding shiva-1-Paulownia is an effective strategy to control PWB disease.
文摘The recent emergence ofseveralplant diseases caused by psyllid-borne bacterial pathogens worldwide (Candidatus Liberibaeter spp.) has created renewed interest on the interaction between psyllids and bacteria. In spite of these efforts to understand psyllid association with bacteria, many aspects of their interactions remain poorly understood. As more organisms are studied, subtleties on the molecular interactions as well as on the effects of the bacteria on the psyllid host are being uncovered. Additionally, psyllid-borne bacterial phytopathogens can also affect the host plant, which in turn can impact psyllid physiology and behavior. Here, we review the current literature on different aspects of the influence of bacteria on multitrophic interactions among plants, psyllids, and pathogens. We then highlight gaps that need to be addressed to advance this field, which can have significant implications for controlling these newly emergent and other plant diseases.
基金P.R.-C.,S.S.,and G.C.are supported by grants from the USDA CDRE(2019-70016-29796,2016-70016-24833)G.C.L.B.is supported by an INRAE Department of Plant Health and Environment(SPE)grant(VMP-ADAPT),grants from the University of Bordeaux,and SFR Integrative Biology and Ecology.M.H.and M.M.are supported by a grant from the USDA ARS CRIS(8062-22410-006-00-D)+1 种基金M.H.W.H.and S.A.H.were funded from the BBSRC Institute Strategy Program(BB/P012574/1)the John Innes Foundation.M.H.and M.M.are funded by USDA ARS project 8062-22410-006-00-D.R.P.P.A.was funded by the Pierce's Disease Research Program,California Department of Food and Agriculture.
文摘Vector-borne plant diseases have significant ecological and economic impacts,affecting farm profitability and forest composition throughout the world.Bacterial vector-borne pathogens have evolved sophisticated strategies to interact with their hemipteran insect vectors and plant hosts.These pathogens reside in plant vascular tissue,and their study represents an excellent opportunity to uncover novel biological mechanisms regulating intracellular pathogenesis and to contribute to the control of some of the world's most invasive emerging diseases.In this perspective,we highlight recent advances and major unanswered questions in the realm of bacterial vector-borne disease,focusing on liberibacters,phytoplasmas,spiroplasmas,and Xylella fastidiosa.