engineering of a single-chain variable-fragment (scfv) antibody specific for the stolbur phytoplasma (mollicute) and its expression in escherichia coli and tobacco plantsfrom a hybridoma cell line (2a10) producing an immunoglobulin g1 directed against the major membrane protein of the stolbur phytoplasma, we have engineered scfv (single-chain variable-fragment) antibodies from the variable heavy (vh) and light (vl) domains of the immunoglobulin. the scfv gene was cloned and expressed in escherichia coli. the expressed protein of 30 kda could be recovered from the periplasmic fraction of the bacterial cells and was shown to be fully functional toward its phytopla ...19989797323
classification of new phytoplasmas associated with diseases of strawberry in florida, based on analysis of 16s rrna and ribosomal protein gene operon sequences.strawberry plants exhibiting symptoms of stunting and abnormally small leaves were observed in production fields in central florida, usa. since the symptoms were suggestive of phytoplasma infection, plants were assayed for presence of phytoplasma by pcr amplification of 16s rdna and ribosomal protein (rp) gene sequences. amplification of phytoplasma-specific dna sequences by pcr indicated infection of the diseased strawberry plants by phytoplasmas. rflp analyses of amplified 16s rdna revealed th ...19989542097
catharanthus roseus genes regulated differentially by mollicute infections.a differential display of mrnas was used to isolate periwinkle cdnas differentially expressed following infection with one of three mollicutes: spiroplasma citri, candidatus phytoplasma aurantifolia, and stolbur phytoplasma. twenty-four differentially expressed cdnas were characterized by northern blots and sequence analysis. eight of them had homologies with genes in databanks coding for proteins involved in photosynthesis, sugar transport, response to stress, or pathways of phytosterol synthes ...200111204786
stolbur phytoplasma genome survey achieved using a suppression subtractive hybridization approach with high specificity.phytoplasmas are unculturable bacterial plant pathogens transmitted by phloem-feeding hemipteran insects. dna of phytoplasmas is difficult to purify because of their exclusive phloem location and low abundance in plants. to overcome this constraint, suppression subtractive hybridization (ssh) was modified and used to selectively amplify dna of the stolbur phytoplasma infecting a periwinkle plant. plasmid libraries were constructed, and the origins of the dna inserts were verified by hybridizatio ...200616672467
'candidatus phytoplasma fragariae', a novel phytoplasma taxon discovered in yellows diseased strawberry, fragaria x ananassa.symptoms of general stunting and yellowing of leaves were observed in diseased cultivated strawberry (fragaria x ananassa duchesne) in lithuania. analysis of 16s rrna gene sequences amplified by pcr indicated that the symptoms were associated with infection by a phytoplasma, designated strawberry yellows (strawy) phytoplasma. phylogenetic analysis of 16s rrna gene sequences indicated that strawy phytoplasma, 'candidatus phytoplasma australiense', 'candidatus phytoplasma asteris', stolbur phytopl ...200616403898
"candidatus phytoplasma australiense," a new phytoplasma taxon associated with australian grapevine yellows.a phytoplasma was detected in naturally diseased 'chardonnay' grapevines exhibiting symptoms of australian grapevine yellows disease. the use of pcr designed to amplify phytoplasma dna resulted in detection of phytoplasma dna in all of the diseased plants examined; no phytoplasma dna was detected in healthy seedling grapevines. the collective restriction fragment length polymorphism (rflp) patterns of amplified 16s ribosomal dna differed from the patterns described previously for other phytoplam ...19979103609
sequence and rflp analysis of the elongation factor tu gene used in differentiation and classification of phytoplasmas.primers designed from sequences of the gene encoding the elongation factor tu (tuf gene) of several culturable mollicutes amplified most of the tuf gene from phytoplasmas of the aster yellows, stolbur and x-disease groups. about 85% of the tuf gene from two aster yellows strains and a tomato stolbur phytoplasma was sequenced. the nucleotide sequence similarity between these related phytoplasmas was between 87.8 and 97.0%, whereas the homology with other mollicutes was 66.3-72.7%. the similarity ...19979353940
tomato flower abnormalities induced by stolbur phytoplasma infection are associated with changes of expression of floral development genes.tomato (lycopersicon esculentum cv. micro-tom) plants infected by the stolbur phytoplasma (isolate po) display floral abnormalities, including sepal hypertrophy, virescence, phyllody, and aborted reproductive organs, which are reminiscent of those observed in arabidopsis thaliana mutants affected in flower development genes. semiquantitative reverse transcription-polymerase chain reaction and in situ rna hybridization were used to compare expressions of meristem and flower development genes in h ...200616404954
occurrence of stolbur phytoplasma disease in spreading type petunia hybrida cultivars in january 2012, spreading type petunia cv. wave pink plants showing an abnormal growth habit of sprouting unusual multiple plantlets from the lateral buds were collected from a greenhouse in gwacheon, gyeonggi province, korea. the presence of phytoplasma was investigated using pcr with the primer pairs p1/p6, and r16f1/r1 for nested-pcr. in the nested pcr, 1,096 bp pcr products were obtained, and through sequencing 12 pet-stol isolates were identified. comparison of the nucleotide sequences of ...201325288978
survival relative to new and ancestral host plants, phytoplasma infection, and genetic constitution in host races of a polyphagous insect disease vector.dissemination of vectorborne diseases depends strongly on the vector's host range and the pathogen's reservoir range. because vectors interact with pathogens, the direction and strength of a vector's host shift is vital for understanding epidemiology and is embedded in the framework of ecological specialization. this study investigates survival in host-race evolution of a polyphagous insect disease vector, hyalesthes obsoletus, whether survival is related to the direction of the host shift (from ...201425247065
'candidatus phytoplasma asteris', a novel phytoplasma taxon associated with aster yellows and related diseases.aster yellows (ay) group (16sri) phytoplasmas are associated with over 100 economically important diseases worldwide and represent the most diverse and widespread phytoplasma group. strains that belong to the ay group form a phylogenetically discrete subclade within the phytoplasma clade and are related most closely to the stolbur phytoplasma subclade, based on analysis of 16s rrna gene sequences. ay subclade strains are related more closely to their culturable relatives, acholeplasma spp., than ...200415280267
'candidatus phytoplasma', a taxon for the wall-less, non-helical prokaryotes that colonize plant phloem and insects.the trivial name 'phytoplasma' has been adopted to collectively name wall-less, non-helical prokaryotes that colonize plant phloem and insects, which were formerly known as mycoplasma-like organisms. although phytoplasmas have not yet been cultivated in vitro, phylogenetic analyses based on various conserved genes have shown that they represent a distinct, monophyletic clade within the class mollicutes. it is proposed here to accommodate phytoplasmas within the novel genus 'candidatus (ca.) phyt ...200415280299
impact of vector dispersal and host-plant fidelity on the dissemination of an emerging plant pathogen.dissemination of vector-transmitted pathogens depend on the survival and dispersal of the vector and the vector's ability to transmit the pathogen, while the host range of vector and pathogen determine the breath of transmission possibilities. in this study, we address how the interaction between dispersal and plant fidelities of a pathogen (stolbur phytoplasma tuf-a) and its vector (hyalesthes obsoletus: cixiidae) affect the emergence of the pathogen. using genetic markers, we analysed the geog ...201223284774
sympatric diversification vs. immigration: deciphering host-plant specialization in a polyphagous insect, the stolbur phytoplasma vector hyalesthes obsoletus (cixiidae).the epidemiology of vector transmitted plant diseases is highly influenced by dispersal and the host-plant range of the vector. widening the vector's host range may increase transmission potential, whereas specialization may induce specific disease cycles. the process leading to a vector's host shift and its epidemiological outcome is therefore embedded in the frameworks of sympatric evolution vs. immigration of preadapted populations. in this study, we analyse whether a host shift of the stolbu ...201323452165
characterization of bois noir isolates by restriction fragment length polymorphism of a stolbur-specific putative membrane protein gene.bois noir phytoplasma (bnp), widespread in wine-producing areas of europe and endemic in france and italy, is classified in the 16srxii-a subgroup, whose members are referred to as stolbur phytoplasmas. the 16s rdna gene of stolbur phytoplasma shows low variability, and few non-ribosomal genes are available as markers to assess variation among isolates. we used the stolbur-specific stol-1h10 gene, encoding a putative membrane-exposed protein, to investigate genetic diversity of french and italia ...200919453230
striking diversity of vmp1, a variable gene encoding a putative membrane protein of the stolbur phytoplasma.studies of phytoplasma-insect vector interactions and epidemiological surveys of plant yellows associated with the stolbur phytoplasma (stolp) require the identification of relevant candidate genes and typing markers. a recent stolp genome survey identified a partial coding sequence, sr01h10, having no homologue in the "candidatus phytoplasma asteris" genome but sharing low similarity with a variable surface protein of animal mycoplasmas. the complete coding sequence and its genetic environment ...200919270150
identification of phytoplasma species associated with potato diseases in russia.four out of six known potato diseases attributed to phytoplasma infection were previously reported to occur in russia based on a combination of biological properties such as symptomatology and/or vector relationships and electron microscopy of infected phloem tissue. in 2007, the first molecular identification of potato diseases causing symptoms including purple top, round leaves, stunting, bud proliferation and formation of aerial tubers was carried out using pcr methods. a nested pcr using pri ...200819226771
oligodeoxynucleotides as probes for in situ hybridization with transmission electron microscopy to specifically localize phytoplasma in plant cells.phytoplasmas are plant-pathogenic mollicutes restricted to phloem. they belong to several groups in a unique phylogenetic clade. non-related phytoplasmas may infect the same plant species, often with similar symptoms. hence methods are needed to specifically localize phytoplasmas and to study their multiplication and movement in their hosts. conditions for post-embedding in situ hybridization (ish) with transmission electron microscopy using oligodeoxynucleotides as probes for labelling of phyto ...199910024432
non-cultivable phytopathogenic mycoplasmas: characterization, detection and perspectives for control.phytoplasmas (ex mlos) and spiroplasmas are important groups of plant pathogenic mollicutes, discovered in 1967 and 1970 respectively. spiroplasmas, like other mollicutes, can be cultured in artificial media and are thus well characterized. on the contrary, phytoplasmas have resisted in vitro cultivation and their study was difficult until the recent development of molecular techniques. from the sequence of their 16s rdna, phytoplasmas have been shown to be true mollicutes. fourteen phytoplasma ...19979286069
bacterial endosymbiont localization in hyalesthes obsoletus, the insect vector of bois noir in vitis emerging disease of grapevine in europe is bois noir (bn), a phytoplasmosis caused by "candidatus phytoplasma solani" and spread in vineyards by the planthopper hyalesthes obsoletus (hemiptera: cixiidae). here we present the first full characterization of the bacterial community of this important disease vector collected from bn-contaminated areas in piedmont, italy. length heterogeneity pcr and denaturing gradient gel electrophoresis analysis targeting the 16s rrna gene revealed the presenc ...201021183640
genetic variability of the stolbur phytoplasma vmp1 gene in grapevines, bindweeds and vegetables.evaluation of the genetic variability of stolbur phytoplasma infecting grapevines, bindweeds and vegetables, collected in different central and southern italian regions.201020846330
the sensory structures of the antennal flagellum in hyalesthes obsoletus (hemiptera: fulgoromorpha: cixiidae): a functional reduction?despite their relevance as harmful pests on plants of economic importance, hemiptera fulgoromorpha have been poorly studied as regards their antennal sensory structures. in particular, the flagellum has been neglected and, therefore, to date there are no data on its structural organization and sensory equipment. in order to fill this gap, we carried out a study on the sensillum types and distribution on the flagellum of the planthopper hyalesthes obsoletus signoret, an efficient vector of the st ...200919682602
phytoplasma infection in tomato is associated with re-organization of plasma membrane, er stacks, and actin filaments in sieve elements.phytoplasmas, biotrophic wall-less prokaryotes, only reside in sieve elements of their host plants. the essentials of the intimate interaction between phytoplasmas and their hosts are poorly understood, which calls for research on potential ultrastructural modifications. we investigated modifications of the sieve-element ultrastructure induced in tomato plants by 'candidatus phytoplasma solani,' the pathogen associated with the stolbur disease. phytoplasma infection induces a drastic re-organiza ...201526347766
stolbur phytoplasma transmission to maize by reptalus panzeri and the disease cycle of maize redness in serbia.maize redness (mr), induced by stolbur phytoplasma ('candidatus phytoplasma solani', subgroup 16srxii-a), is characterized by midrib, leaf, and stalk reddening and abnormal ear development. mr has been reported from serbia, romania, and bulgaria for 50 years, and recent epiphytotics reduced yields by 40 to 90% in south banat district, serbia. potential vectors including leafhoppers and planthoppers in the order hemiptera, suborder auchenorrhyncha, were surveyed in mr-affected and low-mr-incidenc ...200919671007
natural phytoplasma infection of four phloem-feeding auchenorrhyncha across vineyard agroecosystems in central-eastern italy.the seasonal variations of grapevine yellow phytoplasma were investigated in four phloem-feeding planthopper and leafhopper species that are vectors of plant disease agents. in total, 1,148 wild specimens were collected from three vineyard agroecosystems in the marche region (central-eastern italy), from may to september 2008, and analyzed using polymerase chain reaction-restriction fragment-length polymorphism methods. of 525 euscelis lineolatus brullé, 25.1% were positive for aster yellow phyt ...201323786045
the stolbur phytoplasma antigenic membrane protein gene stamp is submitted to diversifying positive selection.surface proteins play an important role in phytoplasma life cycle. the antigenic membrane protein (amp) of 'candidatus phytoplasma asteris' has been shown to interact with the insect microfilaments. due to the synteny of the grol-amp-nade genetic locus between phytoplasma genomes, the gene stamp that encodes the antigenic membrane protein of stolbur phytoplasma has been cloned and characterized. it encodes a 157 amino acid-long protein with a predicted signal peptide and a c-terminal hydrophobic ...201021044666
chromosome sizes of phytoplasmas composing major phylogenetic groups and subgroups.abstract chromosome sizes of 71 phytoplasmas belonging to 12 major phylogenetic groups including several of the aster yellows subgroups were estimated from electrophoretic mobilities of full-length chromosomes in pulsed-field gels. considerable variation in genome size, from 660 to 1,130 kilobases (kb), was observed among aster yellows phytoplasmas. chromosome size heterogeneity was also observed in the stolbur phytoplasma group (range 860 to 1,350 kb); in this group, isolate stolf contains the ...199918944709
source of hyalesthes obsoletus signoret planthopper (hemiptera: cixiidae) in southern france and potential effects of landscape.cixiid planthoppers are considered of major economic importance, as they can transmit phytoplasmas responsible for many plant diseases. while thorougly studied in vineyards, the epidemiology of stolbur phytoplasma, transmitted by hyalesthes obsoletus signoret, was rarely investigated on minor crops as lavender, where it leads to 'yellow decline' disease and large economic losses. the objective of this paper is to understand the effect of the local landscape characteristics on the presence and de ...201728891460
"candidatus phytoplasma americanum", a phytoplasma associated with a potato purple top wilt disease complex.potato purple top wilt (ppt) is a devastating disease that occurs in various regions of north america and mexico. at least three distinct phytoplasma strains belonging to three different phytoplasma groups (16sri, 16srii and 16srvi) have been associated with this disease. a new disease with symptoms similar to ppt was recently observed in texas and nebraska, usa. two distinct phytoplasma strain clusters were identified. one belongs to the 16sri phytoplasma group, subgroup a, and the other is a n ...200616825635
"candidatus phlomobacter fragariae" is the prevalent agent of marginal chlorosis of strawberry in french production fields and is transmitted by the planthopper cixius wagneri (china).abstract marginal chlorosis has affected strawberry production in france for about 15 years. a phloem-restricted uncultured bacterium, "candidatus phlomobacter fragariae," is associated with the disease. a large-scale survey for marginal chlorosis in french strawberry production fields and nurseries by polymerase chain reaction amplification of "ca. p. fragariae" 16s rdna revealed that symptoms of marginal chlorosis were not always induced by "ca. p. fragariae" and that the stolbur phytoplasma c ...200318943049
association with the syndrome "basses richesses" of sugar beet of a phytoplasma and a bacterium-like organism transmitted by a pentastiridius sp.abstract the syndrome "basses richesses" of sugar beet (sbr) was first observed in 1991 in burgundy, france. a cixiid planthopper, pentastiridius beieri, has been proved to be involved in the transmission to sugar beet of a stolbur phytoplasma, which could be detected in some affected plants. in 2000, periwinkle and sugar beet exposed to field-collected cixiids developed symptoms similar to sbr on sugar beet. use of 4'-6-diamidino-2-phenylindole (dapi) staining and transmission electron microsco ...200218942951
vitex agnus-castus is a preferred host plant for hyalesthes obsoletus.hyalesthes obsoletus signoret (homoptera: cixiidae) is a polyphagous planthopper that transmits stolbur phytoplasma (a causative agent of "yellows" disease) to various weeds, members of the solanaceae, and wine grapes (vitis vinifera l.) in europe and the middle east. planthoppers were collected by hand vacuuming eight native plant species. vitex agnus-castus l., a shrub in the verbenaceae, hosted the largest number of h. obsoletus, although olea europaea l. also served as a host for adults. usi ...200516124232
genetic variability of stolbur phytoplasma in hyalesthes obsoletus (hemiptera: cixiidae) and its main host plants in vineyard agroecosystems.bois noir is an economically important grapevine yellows that is induced by 'candidatus phytoplasma solani' and principally vectored by the planthopper hyalesthes obsoletus signoret (hemiptera: cixiidae). this study explores the 'ca. p. solani' genetic variability associated to the nettle-h. obsoletus and bindweed-h. obsoletus systems in vineyard agroecosystems of the central-eastern italy. molecular characterization of 'ca. p. solani' isolates was carried out using polymerase chain reaction/res ...201526470289
'candidatus phytoplasma convolvuli', a new phytoplasma taxon associated with bindweed yellows in four european countries.plants of convolvulus arvensis exhibiting symptoms of undersized leaves, shoot proliferation and yellowing, collectively defined as bindweed yellows, were sampled in different regions of europe and assessed for phytoplasma infection by pcr amplification using phytoplasma universal rrna operon primer pairs. positive results were obtained for all diseased plants. rflp analysis of amplicons comprising the16s rrna gene alone or the16s rrna gene and 16-23s intergenic spacer region indicated that the ...201222247217
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