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
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
[Objective] This study aimed to increase the expression level of immun- odominant membrane protein gene （Imp） of phytoplasmas in E. coil BL21 （DE3）. [Method] On the basis of orthogonal experiment, effects of diffe...[Objective] This study aimed to increase the expression level of immun- odominant membrane protein gene （Imp） of phytoplasmas in E. coil BL21 （DE3）. [Method] On the basis of orthogonal experiment, effects of different culture conditions on recombinant bacteria E. coil BL21-pET-28a（＋）-Imp were investigated. Based on the obtained optimal culture condition, effects of different induction conditions on the ex- pression level of Imp protein were explored. The expression level of Imp fusion pro- tein was analyzed by using SDS-PAGE and Gene Tools software. [Result] The re- sults showed that the optimal conditions for culture were at 37℃, pH 7.0, with liq- uid volume of 20% and oscillation speed of 200 r/min, for induction were at 37℃ for 6 h, with initial OD600 of about 1.5 and IPTG final concentration of 0.1 mmol/L. [Conclusion] The expression level of Imp achieved 70.98 mg/L under the optimal conditions. Optimized conditions for expression of Imp fusion protein in E. coil were determined.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
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
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
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
Leafhopper Cicadulina bipunctata is represented the main insect as a pathogen for phytoplasma disease occurring by insect-transmitted plant viruses in date palm orchards. Therefore, it is important to investigate the ...Leafhopper Cicadulina bipunctata is represented the main insect as a pathogen for phytoplasma disease occurring by insect-transmitted plant viruses in date palm orchards. Therefore, it is important to investigate the potential effect of some insecticides against such insect. The adults of leafhopper C. bipunctata were collected from date palm orchards in Alhasa, Eastern province, Saudi Arabia. Three insecticides from different classes--beta-cyfluthrin （pyrethroids）, imidacloprid （neonicotinoids） and abamectin （natural compounds）--have been evaluated in vivo against adults C. bipunctata. This stage was exposed to residual film of various concentrations of each insecticide on transparent plastic cups using a Potter precision laboratory spray tower. Bioassay test showed that both beta-cyfluthrin and imidacloprid caused 100% mortality by 500 ppm at 24 h after treatment, whereas abamectin gave the same mortality by 50 ppm at the same time. Toxicity values revealed that abameetin was the most potent insecticide compared with beta-cyfluthrin and imidacloprid, where the lethal concentrations LC50 and LC95 were 24.58 ppm and 116.73 ppm at 3 h after treatment, respectively. Therefore, abamectin can be a possible candidate to be applied on date palm or ground grass by the Ministry of Agriculture after successful field experiments.展开更多
[Objectives]The paper was to detect and identify the phytoplasma of Cleome rutidosperma in areca palm yellow leaf disease(YLD)field in Wenchang City,Hainan Province,China.[Methods]The nested PCR technique was employed...[Objectives]The paper was to detect and identify the phytoplasma of Cleome rutidosperma in areca palm yellow leaf disease(YLD)field in Wenchang City,Hainan Province,China.[Methods]The nested PCR technique was employed to amplify the phytoplasma 16S rDNA of C.rutidosperma samples,followed by sequence analysis.Concurrently,this study examined C.rutidosperma in YLD field,collecting symptomatic leaves for phytoplasma detection.[Results]The 16S rDNA sequence of the C.rutidosperma witches'-broom phytoplasma was found to be identical to that of the HNWC5 strain associated with areca palm yellows phytoplasma,leading to the identification of this phytoplasma as belonging to the 16SrII-A subgroup.Field investigations revealed a higher incidence of C.rutidosperma in areca palm fields,with symptoms of leaf yellows observed in six of these fields.Quantitative PCR(qPCR)analysis confirmed the presence of phytoplasma infection in these instances.[Conclusions]Through the analysis of geographical distribution,sequence alignment,and field occurrence data,a significant correlation has been identified between witches'broom disease and YLD.It is proposed that the former may act as an intermediate host for the areca palm yellows phytoplasma.展开更多
Severe growth abnormalities including shoot stunting, leaf blade reduction and flower bud failure of Brussels sprout were observed in Poland. The presence of phytoplasma in diseased as well as in healthy looking plant...Severe growth abnormalities including shoot stunting, leaf blade reduction and flower bud failure of Brussels sprout were observed in Poland. The presence of phytoplasma in diseased as well as in healthy looking plants, was demonstrated by nested polymerase chain reaction assay employing phytoplasma universal rRNA primer pairs-P1/P7 followed by R16F2n/R16R2. Products of PCR primed by R 16F2n/R 16R2 primer pair from naturally infected Brussels sprouts were sequenced. Comparison of the obtained 16S rDNAs revealed high nucleotide sequence identity between analyzed phytoplasma isolates （99.8%-100%）. They were also nearly identical with the sequences of other phytoplasmas isolates from sub-group 16SrI-B, and they were classified as members of ＂Candidatus Phytoplasma asteris＂.展开更多
Jujube witches＇ broom is a devastating disease of Ziziphusjujube that occurs in various jujube regions of China. Nucleic acid extracted from midribs of samples collected from three jujube varieties （＂Suanzao＂, ＂L...Jujube witches＇ broom is a devastating disease of Ziziphusjujube that occurs in various jujube regions of China. Nucleic acid extracted from midribs of samples collected from three jujube varieties （＂Suanzao＂, ＂Lajiaozao＂ and ＂Langzao＂） from symptomatic and asymptomatic shoots were tested by random amplified polymorphic DNA analyses. Using 13 different 10 and 11-bp random primers the amplification of jujube DNA was achieved from all the samples; AMI4 primer provided amplification of specific DNA fragments of about 400 bp, only from samples collected from symptomatic plants. No genetic variations in these varieties were identified using the other 11 arbitrary primers; only with primer AL07 it was possible to differentiate ＂Langzao＂ from the other two varieties tested. All the experiments were repeated 2 times and the results were consistent. Compared with PCR analyses with phytoplasma-specific primers, RAPD techniques resulted to be an alternative rapid and sensitive method for detecting jujube phytoplasmas presence in different jujube varieties.展开更多
The areca palm(Areca catechu L.)is a vital tropical forest species widely utilized for vegetation restoration,landscaping,and greening purposes.Its nuts hold significant importance in traditional medicine,serving as r...The areca palm(Areca catechu L.)is a vital tropical forest species widely utilized for vegetation restoration,landscaping,and greening purposes.Its nuts hold significant importance in traditional medicine,serving as remedies for various ailments such as parasitic infections,digestive disorders,and depression[1–3].Areca palm yellow leaf disease(AYLD)poses a serious threat to areca palm growth.展开更多
Increasing evidence is proving the biological significance of the phytoplasma-secreted proteins.However,besides a few Sec-dependent secretory proteins,no other phytoplasma-secreted proteins have been reported yet.Cand...Increasing evidence is proving the biological significance of the phytoplasma-secreted proteins.However,besides a few Sec-dependent secretory proteins,no other phytoplasma-secreted proteins have been reported yet.Candidatus Phytoplasma ziziphi is a phytoplasma that causes witches’-broom,a devastating jujube disease prevalent in east Asia.In this study,using the SecretomeP server coupled with an Escherichia coli-based alkaline phosphatase assay,we identified 25 non-classically secreted proteins(ncSecPs)from Ca.P.ziziphi,a novel type of secreted protein associated with phytoplasmas.Among them,six were characterized as hypersensitive cell death response(HR)suppressors that significantly attenuated both Bax-and INF1-triggered HR and H_(2)O_(2) accumulation in Nicotiana benthamiana,indicating a so-far unknown role of the phytoplasma-secreted proteins.Further,we demonstrated that despite the diverse subcellular localizations in the N.benthamiana cells,the six HR-suppressing ncSecPs enhanced the gene expression of several known cell death inhibitors,including pathogenesis-related proteins(NbPR-1,NbPR-2,and NbPR-5)and Bax inhibitor-1(NbBI-1 and NbBI-2).Together,our data indicated that Ca.P.ziziphi has evolved an arsenal of ncSecPs that jointly circumvent HR by activating the plant cell death inhibitors,thus providing new insight into understanding the pathogenesis of phytoplasmas.展开更多
Phytoplasmas are small bacterial parasites that lack cell walls and are transmitted in a persistent-propagative manner by insect vectors.However,detailed multiplication patterns and movements of phytoplasmas within ho...Phytoplasmas are small bacterial parasites that lack cell walls and are transmitted in a persistent-propagative manner by insect vectors.However,detailed multiplication patterns and movements of phytoplasmas within host plant and insect vector remain elusive.In this study,a specific antibody against the immunodominant membrane protein(Imp)of rice orange leaf phytoplasma(ROLP)was generated and subjected to the frozen section immune gold labeling assay,immune gold labeling microscopy,and immune fluorescence labeling assay to investigate how ROLP enters,propagates,and spreads in rice and its leafhopper vector Recilia dorsalis at the ultrastructural level.During acquisition and transmission by insect vectors,ROLPs could squeeze and penetrate the multiple membrane/tissue barriers such as microvilli,apical plasmalemma,and basal lamina in the intestines or salivary glands by endocytosis-and exocytosislike mechanism.Furthermore,ROLP infection is restricted to the type IV and V cells of salivary glands.In contrast to the classical binary fission used by most bacteria,electron microscopy reveals that ROLP exploits an asymmetrical budding strategy to replicate in plant hosts and insect vectors.In this process,a cellular protrusion of ROLP forms a bud to reproduce the offspring by fission at the junction between the bud and the ROLP main body.These results clarify the infection characteristics of ROLP in rice and R.dorsalis,which will help guide the formulation of ROLP prevention and control strategies.展开更多
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Supported by Science and Technology Project of Shenzhen City (JC200903180710A)~~
文摘[Objective] This study aimed to increase the expression level of immun- odominant membrane protein gene （Imp） of phytoplasmas in E. coil BL21 （DE3）. [Method] On the basis of orthogonal experiment, effects of different culture conditions on recombinant bacteria E. coil BL21-pET-28a（＋）-Imp were investigated. Based on the obtained optimal culture condition, effects of different induction conditions on the ex- pression level of Imp protein were explored. The expression level of Imp fusion pro- tein was analyzed by using SDS-PAGE and Gene Tools software. [Result] The re- sults showed that the optimal conditions for culture were at 37℃, pH 7.0, with liq- uid volume of 20% and oscillation speed of 200 r/min, for induction were at 37℃ for 6 h, with initial OD600 of about 1.5 and IPTG final concentration of 0.1 mmol/L. [Conclusion] The expression level of Imp achieved 70.98 mg/L under the optimal conditions. Optimized conditions for expression of Imp fusion protein in E. coil were determined.
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 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.
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.
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.
文摘Leafhopper Cicadulina bipunctata is represented the main insect as a pathogen for phytoplasma disease occurring by insect-transmitted plant viruses in date palm orchards. Therefore, it is important to investigate the potential effect of some insecticides against such insect. The adults of leafhopper C. bipunctata were collected from date palm orchards in Alhasa, Eastern province, Saudi Arabia. Three insecticides from different classes--beta-cyfluthrin （pyrethroids）, imidacloprid （neonicotinoids） and abamectin （natural compounds）--have been evaluated in vivo against adults C. bipunctata. This stage was exposed to residual film of various concentrations of each insecticide on transparent plastic cups using a Potter precision laboratory spray tower. Bioassay test showed that both beta-cyfluthrin and imidacloprid caused 100% mortality by 500 ppm at 24 h after treatment, whereas abamectin gave the same mortality by 50 ppm at the same time. Toxicity values revealed that abameetin was the most potent insecticide compared with beta-cyfluthrin and imidacloprid, where the lethal concentrations LC50 and LC95 were 24.58 ppm and 116.73 ppm at 3 h after treatment, respectively. Therefore, abamectin can be a possible candidate to be applied on date palm or ground grass by the Ministry of Agriculture after successful field experiments.
基金Supported by Innovation Platform for Academicians of Hainan Province of China(YSPTZX202151,YSPTZX202138)Hainan Provincial Natural Science Foundation of China(321QN345).
文摘[Objectives]The paper was to detect and identify the phytoplasma of Cleome rutidosperma in areca palm yellow leaf disease(YLD)field in Wenchang City,Hainan Province,China.[Methods]The nested PCR technique was employed to amplify the phytoplasma 16S rDNA of C.rutidosperma samples,followed by sequence analysis.Concurrently,this study examined C.rutidosperma in YLD field,collecting symptomatic leaves for phytoplasma detection.[Results]The 16S rDNA sequence of the C.rutidosperma witches'-broom phytoplasma was found to be identical to that of the HNWC5 strain associated with areca palm yellows phytoplasma,leading to the identification of this phytoplasma as belonging to the 16SrII-A subgroup.Field investigations revealed a higher incidence of C.rutidosperma in areca palm fields,with symptoms of leaf yellows observed in six of these fields.Quantitative PCR(qPCR)analysis confirmed the presence of phytoplasma infection in these instances.[Conclusions]Through the analysis of geographical distribution,sequence alignment,and field occurrence data,a significant correlation has been identified between witches'broom disease and YLD.It is proposed that the former may act as an intermediate host for the areca palm yellows phytoplasma.
文摘Severe growth abnormalities including shoot stunting, leaf blade reduction and flower bud failure of Brussels sprout were observed in Poland. The presence of phytoplasma in diseased as well as in healthy looking plants, was demonstrated by nested polymerase chain reaction assay employing phytoplasma universal rRNA primer pairs-P1/P7 followed by R16F2n/R16R2. Products of PCR primed by R 16F2n/R 16R2 primer pair from naturally infected Brussels sprouts were sequenced. Comparison of the obtained 16S rDNAs revealed high nucleotide sequence identity between analyzed phytoplasma isolates （99.8%-100%）. They were also nearly identical with the sequences of other phytoplasmas isolates from sub-group 16SrI-B, and they were classified as members of ＂Candidatus Phytoplasma asteris＂.
文摘Jujube witches＇ broom is a devastating disease of Ziziphusjujube that occurs in various jujube regions of China. Nucleic acid extracted from midribs of samples collected from three jujube varieties （＂Suanzao＂, ＂Lajiaozao＂ and ＂Langzao＂） from symptomatic and asymptomatic shoots were tested by random amplified polymorphic DNA analyses. Using 13 different 10 and 11-bp random primers the amplification of jujube DNA was achieved from all the samples; AMI4 primer provided amplification of specific DNA fragments of about 400 bp, only from samples collected from symptomatic plants. No genetic variations in these varieties were identified using the other 11 arbitrary primers; only with primer AL07 it was possible to differentiate ＂Langzao＂ from the other two varieties tested. All the experiments were repeated 2 times and the results were consistent. Compared with PCR analyses with phytoplasma-specific primers, RAPD techniques resulted to be an alternative rapid and sensitive method for detecting jujube phytoplasmas presence in different jujube varieties.
基金The raw sequences of AYLP(short reads S1:SRR19151409,short reads S2:SRR29507615,long reads S1:SRR29507613,long reads S2:SRR29507612)have been deposited into NCBI Sequence Read Archive under the BioProject PRJNA835721The draft genome sequence has been deposited into the NCBI genome database(CP169277).
文摘The areca palm(Areca catechu L.)is a vital tropical forest species widely utilized for vegetation restoration,landscaping,and greening purposes.Its nuts hold significant importance in traditional medicine,serving as remedies for various ailments such as parasitic infections,digestive disorders,and depression[1–3].Areca palm yellow leaf disease(AYLD)poses a serious threat to areca palm growth.
基金funded by the National Key Research and Development Program(2021YFC2600602)the National Natural Science Foundation of China(31970126)the Science Innovation Program of Beijing University of Agriculture.
文摘Increasing evidence is proving the biological significance of the phytoplasma-secreted proteins.However,besides a few Sec-dependent secretory proteins,no other phytoplasma-secreted proteins have been reported yet.Candidatus Phytoplasma ziziphi is a phytoplasma that causes witches’-broom,a devastating jujube disease prevalent in east Asia.In this study,using the SecretomeP server coupled with an Escherichia coli-based alkaline phosphatase assay,we identified 25 non-classically secreted proteins(ncSecPs)from Ca.P.ziziphi,a novel type of secreted protein associated with phytoplasmas.Among them,six were characterized as hypersensitive cell death response(HR)suppressors that significantly attenuated both Bax-and INF1-triggered HR and H_(2)O_(2) accumulation in Nicotiana benthamiana,indicating a so-far unknown role of the phytoplasma-secreted proteins.Further,we demonstrated that despite the diverse subcellular localizations in the N.benthamiana cells,the six HR-suppressing ncSecPs enhanced the gene expression of several known cell death inhibitors,including pathogenesis-related proteins(NbPR-1,NbPR-2,and NbPR-5)and Bax inhibitor-1(NbBI-1 and NbBI-2).Together,our data indicated that Ca.P.ziziphi has evolved an arsenal of ncSecPs that jointly circumvent HR by activating the plant cell death inhibitors,thus providing new insight into understanding the pathogenesis of phytoplasmas.
基金supported by the National Natural Science Foundation of China(31871931)the Major International(Regional)Joint Research Program of China(31920103014)Special Fund for Scientific and Technological Innovation of Fujian Agriculture and Forestry University(CXZX2020023A).
文摘Phytoplasmas are small bacterial parasites that lack cell walls and are transmitted in a persistent-propagative manner by insect vectors.However,detailed multiplication patterns and movements of phytoplasmas within host plant and insect vector remain elusive.In this study,a specific antibody against the immunodominant membrane protein(Imp)of rice orange leaf phytoplasma(ROLP)was generated and subjected to the frozen section immune gold labeling assay,immune gold labeling microscopy,and immune fluorescence labeling assay to investigate how ROLP enters,propagates,and spreads in rice and its leafhopper vector Recilia dorsalis at the ultrastructural level.During acquisition and transmission by insect vectors,ROLPs could squeeze and penetrate the multiple membrane/tissue barriers such as microvilli,apical plasmalemma,and basal lamina in the intestines or salivary glands by endocytosis-and exocytosislike mechanism.Furthermore,ROLP infection is restricted to the type IV and V cells of salivary glands.In contrast to the classical binary fission used by most bacteria,electron microscopy reveals that ROLP exploits an asymmetrical budding strategy to replicate in plant hosts and insect vectors.In this process,a cellular protrusion of ROLP forms a bud to reproduce the offspring by fission at the junction between the bud and the ROLP main body.These results clarify the infection characteristics of ROLP in rice and R.dorsalis,which will help guide the formulation of ROLP prevention and control strategies.
