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1.
Int J Syst Evol Microbiol ; 53(Pt 6): 1925-9, 2003 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-14657124

RESUMO

In addition to rice yellow dwarf (RYD) phytoplasma, several phytoplasmas infect gramineous plants, including rice orange leaf, bermuda grass white leaf, brachiaria grass white leaf and sugarcane white leaf phytoplasmas. To investigate whether the RYD phytoplasma is a discrete, species-level taxon, several isolates of the aforementioned phytoplasmas were analysed using PCR-amplified 16S rDNA sequences. Two RYD isolates, RYD-J(T) and RYD-Th, were almost identical (99.2 %), but were distinct (similarities of 96.3-97.9 %) from other phytoplasma isolates of the RYD 16S-group. The notion that the RYD phytoplasma constitutes a unique taxon is also supported by its unique insect vector (Nephotettix sp.), its unique host plant in nature (rice) and its limited geographical distribution (Asia). In Southern blot analysis, chromosomal and extrachromosomal DNA probes of the RYD phytoplasma reportedly did not hybridize with those of closely related phytoplasmas. These properties of the RYD phytoplasma clearly indicate that it represents a novel taxon, 'Candidatus Phytoplasma oryzae'.


Assuntos
Filogenia , Phytoplasma/classificação , Phytoplasma/genética , Sequência de Bases , DNA Bacteriano/genética , DNA Ribossômico/genética , Genoma Bacteriano , Dados de Sequência Molecular , Oryza/microbiologia , Doenças das Plantas/microbiologia , Poaceae/microbiologia , RNA Bacteriano/genética , RNA Ribossômico 16S/genética
2.
Int J Syst Evol Microbiol ; 53(Pt 4): 1037-1041, 2003 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12892123

RESUMO

Phylogenetic relationships of five jujube witches'-broom (JWB) phytoplasma isolates from four different districts, and other phytoplasmas, were investigated by 16S rDNA PCR amplification and sequence analysis. The 16S rDNA sequences of any pair of the five isolates of JWB phytoplasmas were > 99.5% similar. The JWB phytoplasma 16S rDNA sequences were most closely related to that of the elm yellows (EY) phytoplasma in 16S-group VIII. Phylogenetic analysis of the 16S rDNA sequences from the JWB phytoplasma isolates, together with sequences from most of the phytoplasmas archived in GenBank, produced a tree in which the JWB isolates clustered as a discrete subgroup. The uniqueness of the JWB phytoplasma appears to be correlated with a specific insect vector (Hishimonus sellatus) and the host plant (Zizyphus jujuba), or with a specific geographical distribution. The unique properties of the JWB phytoplasma sequences clearly indicate that it represents a novel taxon, 'Candidatus Phytoplasma ziziphi'.


Assuntos
Acholeplasmataceae/classificação , Doenças das Plantas/microbiologia , Ziziphus/microbiologia , Acholeplasmataceae/genética , Acholeplasmataceae/isolamento & purificação , Acholeplasmataceae/patogenicidade , Animais , Sequência de Bases , DNA Bacteriano/genética , DNA Ribossômico/genética , Insetos Vetores/microbiologia , Dados de Sequência Molecular , Filogenia , RNA Bacteriano/genética , RNA Ribossômico 16S/genética
3.
Int J Syst Evol Microbiol ; 52(Pt 5): 1543-1549, 2002 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12361256

RESUMO

In Korea, Japanese chestnut trees (Castanea crenata Sieb. and Zucc.) showing symptoms indicative of witches' broom disease, including abnormally small leaves and yellowing of young leaves, were examined. Since the symptoms were suggestive of a phytoplasma infection, tissues were assayed for phytoplasmas by PCR analysis using a pair of universal primers that amplify a 1.4-kbp phytoplasma 16S rDNA fragment. The phytoplasma-specific fragment was amplified from diseased plants, but not from healthy plants, indicating that a phytoplasma was the causal agent of the chestnut witches' broom (CnWB) disease. The phylogenetic relationship of the CnWB phytoplasma to other phytoplasmas was examined by sequence analysis of the 16S rDNA. A phylogenetic analysis of 16S rDNA sequences of the phytoplasmas placed the CnWB phytoplasma within a distinct subgroup in the phytoplasma clade of the class Mollicutes. The phylogenetic tree indicated that the CnWB phytoplasma is related most closely to coconut phytoplasmas and suggested that they share a common ancestor. The unique properties of the CnWB phytoplasma sequences clearly establish that it represents a novel taxon, 'Candidatus Phytoplasma castaneae'.


Assuntos
Acholeplasmataceae/classificação , Acholeplasmataceae/patogenicidade , Fagaceae/microbiologia , Doenças das Plantas/microbiologia , Acholeplasmataceae/genética , Sequência de Bases , Cocos/microbiologia , DNA Bacteriano/genética , DNA Ribossômico/genética , Coreia (Geográfico) , Dados de Sequência Molecular , Filogenia , RNA Bacteriano/genética , RNA Ribossômico 16S/genética
4.
DNA Cell Biol ; 21(7): 527-34, 2002 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12162807

RESUMO

An 11.4-kbp region of genomic DNA containing the complete S10-spc operon was constructed by an integrative mapping technique with eight plasmid vectors carrying ribosomal protein sequences from onion yellows phytoplasma. Southern hybridization analysis indicated that phytoplasmal S10-spc is a single-copy operon. This is the first complete S10-spc operon of a phytoplasma to be reported, although only a part of six serial genes of the S10 operon is reported previously. The operon has a context of 5'-rps10, rpl3, rpl4, rpl23, rpl2, rps19, rpl22, rps3, rpl16, rpl29, rps17, rpl14, rpl24, rpl5, rps14, rps8, rpl6, rpl18, rps5, rpl30, rpl15, SecY-3', and is composed of 21 ribosomal protein subunit genes and a SecY protein translocase subunit gene. Resembling Bacillus, this operon contains an rpl30 gene that other mollicutes (Mycoplasma genitalium, M. pneumoniae, and M. pulmonis) lack. A phylogenetic tree based on the rps3 sequence showed that phytoplasmas are phylogenetically closer to acholeplasmas and bacillus than to mycoplasmas. In the S10-spc operon, translation may start from either a GTG codon or an ATG codon, and stop at a TGA codon, as has been reported for acholeplasmas and bacillus. However, in mycoplasmas, GTG was found as a start codon, and TGA was found not as a stop codon, but instead as a tryptophan codon. These data derived from the gene organization, and the genetic code deviation support the hypothesis that phytoplasmal genes resemble those of acholeplasmas and Bacillus more than those of other mollicutes.


Assuntos
Acholeplasmataceae/genética , Bacillus subtilis/genética , Genoma Bacteriano , Óperon , Acholeplasmataceae/classificação , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Composição de Bases , Sequência de Bases , Clonagem Molecular , Códon/genética , DNA Bacteriano/química , DNA Bacteriano/genética , Biblioteca Gênica , Código Genético , Vetores Genéticos , Modelos Genéticos , Dados de Sequência Molecular , Família Multigênica , Mycoplasma/genética , Filogenia , Plasmídeos/genética , Homologia de Sequência de Aminoácidos , Especificidade da Espécie
5.
Microbiology (Reading) ; 147(Pt 2): 507-513, 2001 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11158368

RESUMO

A new extrachromosomal DNA, EcOYW1, was cloned from the onion yellows phytoplasma (OY-W). Southern blot and PCR analysis showed that EcOYW1 is not present in the OY-M, a mild symptom line derived from OY-W. We determined the complete nucleotide sequence of EcOYW1; it is a circular dsDNA of 7.0 kbp in length, which contains seven ORFs. ORF1 encoded a homologue of the geminivirus Rep protein. Western immunoblot analysis revealed that this Rep homologue is expressed in OY-W infected plants, suggesting that EcOYW1 replicates via a geminivirus-like rolling-circle replication mechanism. EcOYW1 is the first phytoplasmal extrachromosomal DNA shown to express encoded genes.


Assuntos
Cromossomos Bacterianos/genética , Chrysanthemum cinerariifolium/microbiologia , DNA Helicases/metabolismo , Proteínas de Ligação a DNA , Geminiviridae/genética , Tenericutes/genética , Transativadores/metabolismo , Sequência de Aminoácidos , Clonagem Molecular , DNA Helicases/genética , Replicação do DNA , DNA Bacteriano/genética , Geminiviridae/metabolismo , Dados de Sequência Molecular , Doenças das Plantas/microbiologia , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Tenericutes/metabolismo , Tenericutes/patogenicidade , Transativadores/genética
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