title: Intracellular symbionts of sharpshooters (Insecta: Hemiptera: Cicadellinae) form a distinct clade with a small genome.
abstract: The leafhoppers (Insecta: Hemiptera: Cicadellidae) are the most species-rich group of invertebrates in which intracellular symbionts are usual. Here we present the first molecular characterization of bacteriome-associates in the leafhoppers, with focus on the subfamily Cicadellinae (sharpshooters). Phylogenetic analyses of 16S rDNA sequences from intracellular symbionts residing in the bacteriomes of five host species indicate that these symbionts form a well-defined clade within the gamma-3 Proteobacteria, consistent with an ancient colonization and strict vertical transmission. More extensive gene sequence information is reported for the symbiont of Homalodisca coagulata (Say). The genome size, as determined by pulsed field gel electrophoresis, is approximately 680 kb. This finding, when combined with published results for symbionts of aphids, ants, psyllids and tsetse flies, adds to an emerging pattern which suggests that bacteriome associates often descend from ancient infections by gamma Proteobacteria, and that these lineages have undergone pronounced genome reduction. A new genus and species name, 'Candidatus Baumannia cicadellinicola' (sp. nov.) is proposed for this newly characterized clade of symbiotic bacteria.
authors.affiliation: Department of Ecology and Evolutionary Biology, Biological Sciences West 310, University of Arizona, Tucson 85721, USA. nmoran@u.arizona.edu
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Moran
authors.forename: Colin
authors.initials: C
authors.lastname: Dale
authors.forename: Helen
authors.initials: H
authors.lastname: Dunbar
authors.forename: Wendy A
authors.initials: WA
authors.lastname: Smith
authors.forename: Howard
authors.initials: H
authors.lastname: Ochman
mesh_terms: D000818:Animals; D004269:DNA, Bacterial / Q000032:analysis; D004275:DNA, Ribosomal / Q000032:analysis; D020563:Gammaproteobacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D016680:Genome, Bacterial; D006430:Hemiptera / Q000382:microbiology*; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S; D017422:Sequence Analysis, DNA; D013559:Symbiosis
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S