Genotyping Points to Divergent Evolution of 'Candidatus Phytoplasma asteris' Strains Causing North American Grapevine Yellows and Strains Causing Aster Yellows.

Grapevine yellows diseases occur in cultivated grapevine (Vitis vinifera L.) on several continents, where the diseases are known by different names depending upon the identities of the causal phytoplasmas. In this study, phytoplasma strains associated with grapevine yellows disease (North American grapevine yellows [NAGY]) in vineyards of Pennsylvania were characterized as belonging to 16S ribosomal RNA (rRNA) gene restriction fragment length polymorphism group 16SrI (aster yellows phytoplasma group), subgroup 16SrI-B (I-B), and variant subgroup I-B*.

'Candidatus Phytoplasma luffae', a novel taxon associated with witches' broom disease of loofah, Luffa aegyptica Mill.

The phytoplasma associated with witches' broom disease of loofah [Luffa aegyptica Mill., syn. Luffa cylindrica (L.

'Candidatus Phytoplasma hispanicum', a novel taxon associated with Mexican periwinkle virescence disease of Catharanthus roseus.

Mexican periwinkle virescence (MPV) phytoplasma was originally discovered in diseased plants of Madagascar periwinkle (Catharanthus roseus) in Yucatán, Mexico. On the basis of results from RFLP analysis of PCR-amplified 16S rRNA gene sequences, strain MPV was previously classified as the first known member of phytoplasma group 16SrXIII, and a new subgroup (16SrXIII-A) was established to accommodate MPV phytoplasma. Phylogenetic analysis of 16S rRNA gene sequences indicated that strain MPV represents a lineage distinct from previously described 'CandidatusPhytoplasma' species.

Complete Genome Sequence of Spiroplasma kunkelii Strain CR2-3x, Causal Agent of Corn Stunt Disease in Zea mays L.

Spiroplasma kunkelii causes corn stunt disease of Zea mays L. in the Americas. Here, we report the nucleotide sequence of the 1,463,926-bp circular chromosome and four plasmids of strain CR2-3x.

Unraveling the Etiology of North American Grapevine Yellows (NAGY): Novel NAGY Phytoplasma Sequevars Related to 'Candidatus Phytoplasma pruni'.

North American grapevine yellows (NAGY) disease has sometimes been attributed to infection of Vitis vinifera L. by Prunus X-disease phytoplasma ('Candidatus Phytoplasma pruni') but this attribution may not be fully adequate. In this study, phytoplasma strains related to 'Ca.

'Candidatus Phytoplasma pruni', a novel taxon associated with X-disease of stone fruits, Prunus spp.: multilocus characterization based on 16S rRNA, secY, and ribosomal protein genes.

X-disease is one of the most serious diseases known in peach (Prunus persica). Based on RFLP analysis of 16S rRNA gene sequences, peach X-disease phytoplasma strains from eastern and western United States and eastern Canada were classified in 16S rRNA gene RFLP group 16SrIII, subgroup A. Phylogenetic analyses of 16S rRNA gene sequences revealed that the X-disease phytoplasma strains formed a distinct subclade within the phytoplasma clade, supporting the hypothesis that they represented a lineage distinct from those of previously described 'Candidatus Phytoplasma' species.

'Candidatus Phytoplasma sudamericanum', a novel taxon, and strain PassWB-Br4, a new subgroup 16SrIII-V phytoplasma, from diseased passion fruit (Passiflora edulis f. flavicarpa Deg.).

Symptoms of abnormal proliferation of shoots resulting in formation of witches'-broom growths were observed on diseased plants of passion fruit (Passiflora edulis f. flavicarpa Deg.) in Brazil.

Physical and genetic map of the Spiroplasma kunkelii CR2-3x chromosome.

Spiroplasma kunkelii (class Mollicutes) is the characteristically helical, wall-less bacterium that causes corn stunt disease. A combination of restriction enzyme analysis, pulsed-field gel electrophoresis (PFGE), and Southern hybridization analysis was used to construct a physical and genetic map of the S. kunkelii CR2-3x chromosome.

Cryptic plasmid pSKU146 from the wall-less plant pathogen Spiroplasma kunkelii encodes an adhesin and components of a type IV translocation-related conjugation system.

A cryptic plasmid of the wall-less plant pathogenic mollicute, Spiroplasma kunkelii CR2-3X, was cloned and its sequence analyzed. The 14,615 bp plasmid, designated pSKU146, has a nucleotide content of 28 mol% G + C, and contains 18 potential protein-coding regions (open reading frames, ORFs), of which six encode proteins that exhibit similarity to virulence-associated proteins involved in cell-to-cell adhesion or conjugal DNA transfer. One ORF encodes a 96 kDa protein, SkARP1, that is highly similar to SARP1 adhesin involved in attachment of Spiroplasma citri to insect vector gut membrane.

Folate biosynthesis pseudogenes, PsifolP and PsifolK, and an O-sialoglycoprotein endopeptidase gene homolog in the phytoplasma genome.

Phytoplasmas are wall-less phytopathogenic prokaryotes of small genome sizes that are obligate parasites of insect vectors and plant hosts. We have cloned a clover phyllody (CPh) phytoplasma DNA locus containing five potential coding sequences. Two were identified as pseudogenes (PsifolP and PsifolK) homologous to folP and folK genes, which encode dihydropteroate synthase (DHPS) and 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK), respectively, in other bacteria.

Differential amplification of sequence heterogeneous ribosomal RNA genes and classification of the 'Fragaria multicipita' phytoplasma.

Ribosomal (r) RNA interoperon sequence heterogeneity in the 'Fragaria multicipita' phytoplasma, a member of group 16SrVI, was initially observed in RFLP patterns of rDNA amplified in the polymerase chain reaction (PCR), and was confirmed through sequence analysis of cloned rDNA. Sequences from operons rrnA and rrnB were amplified in PCR primed by primer pair P1/P7 but from only rrnA in PCR primed by primer pair R16mF2/R16mR1. Preferential amplification of DNA from operon rrnA was explained by base mismatches between the R16mF2/R16mR1 primers and primer annealing sites in rrnB.

Erigeron Witches'-Broom Phytoplasma in Brazil Represents New Subgroup VII-B in 16S rRNA Gene Group VII, the Ash Yellows Phytoplasma Group.

A previously undescribed phytoplasma, Erigeron witches'-broom phytoplasma, was detected in diseased plants of Erigeron sp. and Catharanthus roseus exhibiting symptoms of witches'-broom and chlorosis in the state of São Paulo, Brazil. On the basis of restriction fragment length polymorphism (RFLP) analysis of 16S rDNA amplified in the polymerase chain reaction (PCR), Erigeron witches'-broom phytoplasma was classified in group 16SrVII (ash yellows phytoplasma group), new subgroup VII-B.

Revised Subgroup Classification of Group 16SrV Phytoplasmas and Placement of Flavescence Dorée-Associated Phytoplasmas in Two Distinct Subgroups.

The subgroup classification of phytoplasmas in 16S rRNA group 16SrV (elm yellows phytoplasma group) was revised and extended on the basis of enzymatic restriction fragment length polymorphism (RFLP) analysis of ribosomal (r) DNA and analysis of putative restriction sites in nucleotide sequences. A 1.85 kbp fragment of the rRNA operon from flavescence dorée (FD) phytoplasma strain FD70 from France was amplified and cloned, and its nucleotide sequence determined (GenBank acc.

Design of a Polymerase Chain Reaction for Specific Detection of Corn Stunt Spiroplasma.

Corn stunt disease is a major limiting factor in production of corn (Zea mays) in the Americas. To develop a polymerase chain reaction (PCR) assay specific for detection of the causal agent, Spiroplasma kunkelii, PCR primers were designed on the basis of unique regions of the nucleotide sequence of the S. kunkelii spiralin gene.

Single and Mixed Phytoplasma Infections in Phyllody- and Dwarf-Diseased Clover Plants in Lithuania.

Naturally diseased plants of clover (Trifolium spp.) exhibiting symptoms of clover phyllody (virescence and phyllody of flowers) or of clover dwarf (abnormally small leaves, shortened internodes, proliferation of shoots, and dwarf growth habit) were observed in fields in Lithuania. Phytoplasma group-specific polymerase chain reactions (PCRs) and restriction fragment length polymorphism (RFLP) analysis of 16S rDNA revealed that the plants were infected by two mutually distinct phytoplasmas.

Two Groups of Phytoplasmas from Japan Distinguished on the Basis of Amplification and Restriction Analysis of 16S rDNA.

Phytoplasmas (mycoplasmalike organisms, MLOs) associated with mitsuba (Japanese hone-wort) witches'-broom (JHW), garland chrysanthemum witches'-broom (GCW), eggplant dwarf (ED), tomato yellows (TY), marguerite yellows (MY), gentian witches'-broom (GW), and tsu-wabuki witches'-broom (TW) in Japan were investigated by polymerase chain reaction (PCR) amplification of DNA and restriction enzyme analysis of PCR products. The phytoplasmas could be separated into two groups, one containing strains JHW, GCW, ED, TY, and MY, and the other containing strains GW and TW, corresponding to two groups previously recognized on the basis of transmission by Macrosteles striifrons and Scleroracus flavopictus, respectively. The strains transmitted by M.