title: Secondary endosymbionts of psyllids have been acquired multiple times.
abstract: Previous studies have established that psyllids (Hemiptera, Psylloidea) contain primary endosymbionts, designated as Carsonella ruddii, which cospeciate with the psyllid host. This association appears to be the consequence of a single infection of a psyllid ancestor with a bacterium. Some psyllids may have additional secondary (S-) endosymbionts. We have cloned and sequenced the 16S-23S ribosomal RNA genes of seven representative psyllid S-endosymbionts. Comparison of the S-endosymbiont phylogenetic trees with those of C. ruddii indicates a lack of congruence, a finding consistent with multiple infections of psyllids with different precursors of the S-endosymbionts and/or possible horizontal transmission. Additional comparisons indicate that the S-endosymbionts are related to members of the Enterobacteriaceae as well as to several other endosymbionts and insect-associated bacteria.
authors.affiliation: Microbiology Section, University of California, Davis, CA 95616-8665, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Thao
authors.forename: M A
authors.initials: MA
authors.lastname: Clark
authors.forename: L
authors.initials: L
authors.lastname: Baumann
authors.forename: E B
authors.initials: EB
authors.lastname: Brennan
authors.forename: N A
authors.initials: NA
authors.lastname: Moran
authors.forename: P
authors.initials: P
authors.lastname: Baumann
mesh_terms: D000818:Animals; D001419:Bacteria / Q000145:classification / Q000235:genetics*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D004755:Enterobacteriaceae / Q000235:genetics; D006430:Hemiptera / Q000382:microbiology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D012338:RNA, Ribosomal, 23S / Q000032:analysis; D013559:Symbiosis
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012338:RNA, Ribosomal, 23S