Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/1999
Publication Date: N/A
Technical Abstract: Analysis of conserved 16S rRNA and, to lesser extent, 23S rRNA sequences has been widely applied for identification and classification of uncultured plant pathogenic bacteria, notably, phytoplasmas. Organismic phylogeny derived by comprehensive analyses of 16S rRNA and other conserved sequences (e.g. ribosomal protein gene operon) from representative phytoplasma groups sforms a basis for classification of various phytoplasmas associated with plants and insect vectors. Each phylogenetically distinct lineage (subclade) delineated within the phytoplasma clade was proposed to represent at least a species. In practice, RFLP analysis of PCR-amplified 16S rDNA sequences is used for differentiation and identification of phytoplasma groups. Phytoplasma 16S rRNA RFLP groups thus delineated are consistent with their corresponding phylogenetic subclades. rRNA analysis has also been employed for identification of other uncultured bacteria that tare associated with citrus greening, marginal chlorosis of strawberry, and yellow vine of cucurbits diseases. The merits and limitations of rRNA as a taxonomic tool will be discussed.