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secy gene sequence analysis for finer differentiation of diverse strains in the aster yellows phytoplasma group.aster yellows (ay) group (16sri) phytoplasmas are associated with more than 100 economically important diseases worldwide and represent the most diverse and widespread phytoplasma group. phylogenetic analysis of secy gene sequences resolved 10 genetically distinct lineages. the 10 lineages coincide with those delineated by phylogenetic analysis based on ribosomal protein (rp) gene sequences. however, greater genetic variability among the 10 lineages was revealed based on secy gene sequences. the ...200616330183
characterization of putative membrane protein genes of the 'candidatus phytoplasma asteris', chrysanthemum yellows isolate.to characterize potentially important surface-exposed proteins of the phytoplasma causing chrysanthemum yellows (cy), new primers were designed based on the conserved regions of 3 membrane protein genes of the completely sequenced onion yellows and aster yellows witches' broom phytoplasmas and were used to amplify cy dna. the cy genes secy, amp, and arti, encoding the protein translocase subunit secy, the antigenic membrane protein amp and the arginine transporter arti, respectively, were cloned ...200818449218
pathogenicity of aster yellows phytoplasma and spiroplasma citri on periwinkle.abstract using murashige and skoog (ms) as a basal medium, the effects of varying levels and combinations of plant growth regulators required for shoot tip and root proliferation in healthy and aster yellows phytoplasma (ayp)- and spiroplasma citri-infected periwinkle (catharanthus roseus) shoots were studied. number of shoots and fresh and dry mass of healthy and ayp-infected shoots increased when benzyladenine (ba) concentrations were increased from 0.5 to 4 mg/liter. the maximum number of sho ...199818944838
response of mycorrhizal periwinkle plants to aster yellows phytoplasma infection.the objective of our research was to assess if arbuscular mycorrhizal (am) fungal colonization can modify the effect of infection by two aster yellows phytoplasma strains (ay1, aysim) in catharanthus roseus plants. both phytoplasma strains had a negative effect on the root fresh weight, but they differed in symptoms appearance and in their influence on photosynthetic and transpiration rates of the periwinkle plants. am plants showed significantly reduced shoot fresh weight, while the transpirati ...201019756778
the use of high-throughput small rna sequencing reveals differentially expressed micrornas in response to aster yellows phytoplasma-infection in vitis vinifera cv. 'chardonnay'.phytoplasmas are cell wall-less plant pathogenic bacteria responsible for major crop losses throughout the world. in grapevine they cause grapevine yellows, a detrimental disease associated with a variety of symptoms. the high economic impact of this disease has sparked considerable interest among researchers to understand molecular mechanisms related to pathogenesis. increasing evidence exist that a class of small non-coding endogenous rnas, known as micrornas (mirnas), play an important role i ...201728813447
post-translational cleavage and self-interaction of the phytoplasma effector sap11.phytoplasmas are insect-transmitted intracellular plant bacterial pathogens that secrete effector molecules into host cells that interfere with the host's developmental or metabolic processes. recently, the secreted aster yellows phytoplasma strain witches' broom protein11 (sap11) has been shown to act as a virulence factor that alters the development, hormone biosynthesis, phosphate (pi) homeostasis, and defense responses in the affected plants. we found that sap11 undergoes proteolytic process ...201424776784
transgenic plants that express the phytoplasma effector sap11 show altered phosphate starvation and defense responses.phytoplasmas have the smallest genome among bacteria and lack many essential genes required for biosynthetic and metabolic functions, making them unculturable, phloem-limited plant pathogens. in this study, we observed that transgenic arabidopsis (arabidopsis thaliana) expressing the secreted aster yellows phytoplasma strain witches' broom protein11 shows an altered root architecture, similarly to the disease symptoms of phytoplasma-infected plants, by forming hairy roots. this morphological cha ...201424464367
Phytoplasma effector SAP54 induces indeterminate leaf-like flower development in Arabidopsis plants.Phytoplasmas are insect-transmitted bacterial plant pathogens that cause considerable damage to a diverse range of agricultural crops globally. Symptoms induced in infected plants suggest that these phytopathogens may modulate developmental processes within the plant host. We report herein that Aster Yellows phytoplasma strain Witches' Broom (AY-WB) readily infects the model plant Arabidopsis (Arabidopsis thaliana) ecotype Columbia, inducing symptoms that are characteristic of phytoplasma infect ...201121849514
phytoplasma protein effector sap11 enhances insect vector reproduction by manipulating plant development and defense hormone biosynthesis.phytoplasmas are insect-transmitted phytopathogenic bacteria that can alter plant morphology and the longevity and reproduction rates and behavior of their insect vectors. there are various examples of animal and plant parasites that alter the host phenotype to attract insect vectors, but it is unclear how these parasites accomplish this. we hypothesized that phytoplasmas produce effectors that modulate specific targets in their hosts leading to the changes in plant development and insect perfor ...201122065743
mobile units of dna in phytoplasma genomes.phytoplasmas are obligate symbionts of plants and insects that are responsible for significant yield losses in diverse crops. genome sequencing has revealed that many phytoplasma genomes appear to contain repeated genes organized in units of approximately 20 kb. these 'potential mobile units' (pmus) resemble composite replicative transposons. pmus contain several genes for recombination and some also contain putative 'virulence genes'. genome alignments suggest that pmus are involved in phytopla ...201020860089
phytoplasma pmu1 exists as linear chromosomal and circular extrachromosomal elements and has enhanced expression in insect vectors compared with plant hosts.phytoplasmas replicate intracellularly in plants and insects and are dependent on both hosts for dissemination in nature. phytoplasmas have small genomes lacking genes for major metabolic pathways. nevertheless, their genomes harbour multicopy gene clusters that were named potential mobile units (pmus). pmu1 is the largest most complete repeat among the pmus in the genome of aster yellows phytoplasma strain witches' broom (ay-wb). pmu1 is c. 20 kb in size and contains 21 genes encoding dna repli ...201020662777
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
ay-wb phytoplasma secretes a protein that targets plant cell nuclei.the fully sequenced genome of aster yellows phytoplasma strain witches' broom (ay-wb; candidatus phytoplasma asteris) was mined for the presence of genes encoding secreted proteins based on the presence of n-terminal signal peptides (sp). we identified 56 secreted ay-wb proteins (sap). these sap are candidate effector proteins potentially involved in interaction with plant and insect cell components. one of these sap, sap11, contains an n-terminal sp sequence and a eukaryotic bipartite nuclear l ...200919061399
range of phytoplasma concentrations in various plant hosts as determined by competitive polymerase chain reaction.abstract for competitive polymerase chain reaction (pcr), an internal standard dna template was developed that consisted of a highly conserved, internally deleted 16s rdna fragment of an aster yellows phytoplasma. the internal standard was calibrated using a quantified culture of acholeplasma laidlawii. serial dilutions of the internal standard and fixed amounts of target templates from infected plants were coamplified with the same primers, and the products obtained were quantified using an enz ...200018944479
living with genome instability: the adaptation of phytoplasmas to diverse environments of their insect and plant hosts.phytoplasmas ("candidatus phytoplasma," class mollicutes) cause disease in hundreds of economically important plants and are obligately transmitted by sap-feeding insects of the order hemiptera, mainly leafhoppers and psyllids. the 706,569-bp chromosome and four plasmids of aster yellows phytoplasma strain witches' broom (ay-wb) were sequenced and compared to the onion yellows phytoplasma strain m (oy-m) genome. the phytoplasmas have small repeat-rich genomes. this comparative analysis revealed ...200616672622
detection and molecular characterization of an aster yellows phytoplasma in poker statice and queen anne's lace in alberta, canada.queen anne's lace and poker statice plants were found with a yellows-type disease with typical phytoplasma symptoms in an experimental farm near brooks, alberta in 1996. phytoplasma bodies were detected by transmission electron microscopy in phloem cells of symptomatic plants, but not in healthy plants. the presence of a phytoplasma was confirmed by analysis with the polymerase chain reaction. using a pair of universal primer sequences derived from phytoplasma 16s rrna, an amplified product of t ...200415160606
secretion of immunodominant membrane protein from onion yellows phytoplasma through the sec protein-translocation system in escherichia coli.a gene that encodes a putative sece protein, which is a component of the sec protein-translocation system, was cloned from the onion yellows phytoplasma (oy). the identification of this gene and the previously reported genes encoding seca and secy provides evidence that the sec system exists in phytoplasma. in addition, a gene encoding an antigenic membrane protein (amp) (a type of immunodominant membrane protein) of oy was cloned and sequenced. the oy amp gene consisted of 702 nt encoding a pro ...200414702406
identification of aster yellows phytoplasma in garlic and green onion by pcr-based methods.in the summer of 1999, typical yellows-type symptoms were observed on garlic and green onion plants in a number of gardens and plots around edmonton, alberta, canada. dna was extracted from leaf tissues of evidently healthy and infected plants. dna amplifications were conducted on these samples, using two primer pairs, r16f2n/r2 and r16(1)f1/r1, derived from phytoplasma rdna sequences. dna samples of aster yellows (ay), lime witches'-broom (lwb) and potato witches'-broom (pwb) phytoplasmas serve ...200212398284
detection of aster yellows phytoplasma in false flax based on pcr and rflp.false flax (camelina sativa l.) plants were found to be infected with a yellows-type disease caused by a phytoplasma in experimental plots at the edmonton research station. alberta, canada. typical phytoplasmas were detected in the phloem cells in ultrathin sections from leaf midrib tissues examined by electron microscopy. these observations were supported by polymerase chain reaction (pcr) using two primer pairs, r16 f2n/r2 and r16(1)f1/r1, derived from phytoplasma rdna sequences. aster yellows ...200111572458
heteroduplex mobility assay detects dna mutations for differentiation of closely related phytoplasma strains.we present the first use of dna heteroduplex mobility assay (hma) to detect the point mutations including substitutions and deletions/insertions in 16s rdna of aster yellows phytoplasma (ay27) and to differentiate phytoplasmas collected from field samples of clover proliferation (cp) and alfalfa witches'-broom (awb). the phytoplasmal 16s rdna fragment was amplified from ay27 by polymerase chain reaction (pcr) and cloned into a plasmid vector. the cloned dna fragment was subjected to in vitro mut ...200010856778
molecular and microscopical detection of aster yellows phytoplasma associated with infected parsnip.typical phytoplasma yellows symptoms were observed in parsnip (pastinaca sativa l.) plants grown around edmonton, alberta, canada. examination of ultrathin sections of leaf midribs by electron microscopy revealed numerous phytoplasma bodies localized in the phloem cells. dna extracted from the infected leaves was amplified with a 16s rdna universal primer pair p1/p6 giving the expected pcr product of 1.5 kb. the phytoplasma was confirmed as a member of the aster yellows (ay) group by amplificati ...200010830901
identification and characterization of plasmids from the western aster yellows mycoplasmalike organism.supercoiled double-stranded dna molecules (plasmids) were isolated from plants infected with three laboratory strains of western aster yellows mycoplasma-like organism (ay-mlo) by using cesium chloride-ethidium bromide density gradients. southern blot analysis, using plasmids from the severe strain of ay-mlo (say-mlo) as the probe, identified at least four plasmids in celery, aster, and periwinkle plants and in macrosteles severini leafhopper vectors infected with either the dwarf ay-mlo, tulela ...19902307660
banded filaments associated with the aster yellows mlo in vinca rosea l.the ultrastructure of an aster yellows mycoplasma-like organism was studied in the phloem of periwinkle (vinca rosea l.) plants. banded filaments were observed in association with mycoplasma-like organisms of characteristic morphology. the filaments were variable in length, from 50-100 nm in width, and displayed a regular periodic banding of alternating electron-dense and electron-lucent structures.1978570447
detection and variability of aster yellows phytoplasma titer in its insect vector, macrosteles quadrilineatus (hemiptera: cicadellidae).the aster yellows phytoplasma (ayp) is transmitted by the aster leafhopper, macrosteles quadrilineatus forbes, in a persistent and propagative manner. to study ayp replication and examine the variability of ayp titer in individual aster leafhoppers, we developed a quantitative real-time polymerase chain reaction assay to measure ayp concentration in insect dna extracts. absolute quantification of ayp dna was achieved by comparing the amplification of unknown amounts of an ayp target gene sequenc ...201122299339
insect maintenance and transmission.phytoplasmas are plant pathogens of huge economic importance due to responsibility for crop yield losses worldwide. institutions around the world are trying to understand and control this yield loss at a time when food security is high on government agendas. in order to fully understand the mechanisms of phytoplasma infection and spread, more insect vector and phytoplasma colonies will need to be established for research worldwide. rearing and study of these colonies is essential in the research ...201322987405
factors influencing aster leafhopper (hemiptera: cicadellidae) abundance and aster yellows phytoplasma infectivity in wisconsin carrot fields.in wisconsin, vegetable crops are threatened annually by infection of the aster yellows phytoplasma (ayp), the causal agent of aster yellows (ay) disease, vectored by the aster leafhopper, macrosteles quadrilineatus forbes. aster leafhopper abundance and infectivity are influenced by processes operating across different temporal and spatial scales. we applied a multilevel modeling approach to partition variance in multifield, multiyear, pest scouting data sets containing temporal and spatial cov ...201323726057
seasonal patterns of aster leafhopper (hemiptera: cicadellidae) abundance and aster yellows phytoplasma infectivity in wisconsin carrot fields.in wisconsin, vegetable crops are threatened annually by the aster yellows phytoplasma (ayp), which is obligately transmitted by the aster leafhopper. using a multiyear, multilocation data set, seasonal patterns of leafhopper abundance and infectivity were modeled. a seasonal aster yellows index (ayi) was deduced from the model abundance and infectivity predictions to represent the expected seasonal risk of pathogen transmission by infectious aster leafhoppers. the primary goal of this study was ...201323726058
the small phytoplasma virulence effector sap11 contains distinct domains required for nuclear targeting and cin-tcp binding and destabilization.phytoplasmas are insect-transmitted bacterial phytopathogens that secrete virulence effectors and induce changes in the architecture and defense response of their plant hosts. we previously demonstrated that the small (± 10 kda) virulence effector sap11 of aster yellows phytoplasma strain witches' broom (ay-wb) binds and destabilizes arabidopsis cin (cincinnata) tcp (teosinte-branched, cycloidea, proliferation factor 1 and 2) transcription factors, resulting in dramatic changes in leaf morphogen ...201424552625
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