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Submitted to: Encyclopedia of Microbiology
Publication Type: Book / Chapter Publication Acceptance Date: 4/20/1999 Publication Date: N/A Citation: N/A Interpretive Summary: Phytoplasmas are unique bacteria that are linked with serious, economically damaging diseases of plants worldwide. In this article, we present a brief overview of the history of phytoplasma discovery, and we discuss plant diseases caused by phytoplasmas, the detection of phytoplasmas in infected host plants and in insect vectors, phytoplasma classification, and the taxonomy and phylogeny of phytoplasmas, the phytoplasma genome, and the epidemiology of plant diseases caused by phytoplasmas. The information in the article will be of interest to scientists whose fields of expertise are outside that of phytoplasmas, to persons involved in agricultural extension activities and the regulation of plant quarantine regulations, and to students of microbiology. Technical Abstract: Phytoplasmas (previously called mycoplasmalike organisms, MLOs) are minute wall-less bacteria that are found in the phloem tissues of plants and in the bodies of insect vectors that transmit them from plant-to-plant. Diseases attributed to phytoplasmas are among the most damaging diseases of plants. Modern molecular methods for the detection of phytoplasmas in plant and insect tissues are greatly aiding the diagnosis of phytoplasmal diseases of plants. Polymerase chain reactions using primers derived from conserved 16S ribosomal (r)RNA gene sequences has provided the most widely used, sensitive means for detection of a broad array of phytoplasmas from infected plants or insect vectors. Because it has not been possible to isolate phytoplasmas in pure culture, the convention of "Candidatus Phytoplasma" species has been adopted to make it possible to refer to distinct lineages of phytoplasmas. Three have been named: "Candidatus Phytoplasma aurantifolia" (lime witches' broom phytoplasma), "Candidatus Phytoplasma australiense" (Australian grapevine yellows phytoplasma), and "Candidatus Phytoplasma australasia" (Papaya yellow crinkle phytoplasma). |
