Phytoplasmas are uncultivable prokaryotic wall-less pathogens belonging to the class Mollicutes that inhabit plant phloem and insects. Their identification and classification is difficult and mainly based on the polymorphism of their 16S rRNAgene sequences. Aster yellows (AY; 'Candidatus Phytoplasma asteris') phytoplasmas (ribosomal subgroup 16SrI-P) had been previously identified in several Po...

Three genes encoding membrane proteins of chrysanthemum yellows (CY) phytoplasma were cloned and sequenced: SecY, Amp and ArtI encoding the protein translocase subunit SecY, the antigenic membrane protein Amp and the arginine transporter ArtI, respectively. Alignments of CY-specific SecY sequences with the corresponding genes of other phytoplasmas confirmed the 16SrDNA-based classification, whi...

The present paper describes a new approach for diagnosis of apple proliferation (AP) phytoplasma in plant material using a multiplex real-time PCR assay simultaneously amplifying a fragment of the pathogen 16S rRNA gene and the host, Malus domestica, chloroplast gene coding for tRNA leucine. For the first time, such an approach, with an internal analytical control, is described in a diagnostic ...

Hibiscus rosa-sinensis is a valuable ornamental species widely planted in Brazil. Many plants are affected by witches' broom disease, which is characterized by excessive axillary branching, abnormally small leaves, and deformed flowers, symptoms that are characteristic of diseases attributed to phytoplasmas. A phytoplasma was detected in diseased Hibiscus by amplification of rRNA operon sequenc...

Phytoplasmas (class, Mollicutes) are insect-transmissible and plant-pathogenic bacteria that multiply intracellularly in both plants and insects through host switching. Our previous study revealed that phytoplasmal sigma factor rpoD of OY-M strain (rpoDOY) could be a key regulator of host switching, because the expression level of rpoDOY was higher in insect hosts than in plant hosts. In this s...

Part of the Master Thesis of the first author. Universidade Federal Rural do Rio de Janeiro. Seropédica RJ. 2008. ABSTRACT Phytoplasmas can cause yield losses in numerous crops worldwide. In Brazil, phytoplasmal diseases have been reported in plant species, distributed among 29 botanical families. Chayote witches’-broom (ChWB) is reported as one of the diseases of economic importance, associate...

The detection of phytoplasmas in fruit trees and other important crops is demanded from nurseries and certification agencies. We have therefore developed an efficient assay for general detection of phytoplasmas. This duplex assay combines the phytoplasma detection with an internal control, detecting host gene 18S rRNA in the same reaction. The internal control enables the confirmation of an eff...

Phytopathogenic mollicutes, which include spiroplasmas and phytoplasmas, are cell wall-less bacteria that parasitize plant hosts and insect vectors. Knowledge of the evolution of these agents is important in understanding their biology. The availability of the first complete phytoplasma and several partial spiroplasma and phytoplasma genome sequences made possible an investigation of evolutiona...

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 infec...

During the last two decades, over 800 phytoplasma strains have been reported in association with several hundred plant diseases and numerous insect vectors. Research has yielded new knowledge about phytoplasma ecology and phylogenetic relationships. A taxonomic system has emerged, and perspectives on phytoplasma speciation have changed. Guidelines for naming new ‘Candidatus Phytoplasma’ species...