Secondary (γ- Proteobacteria ) Endosymbionts Infect the Primary (β- Proteobacteria ) Endosymbionts of Mealybugs Multiple Times and Coevolve with Their Hosts

Publication

Citation

Thao et al. (2002). Applied and Environmental Microbiology 68 (7)

Names (2)

Ca. Tremblaya princeps

“Tremblaya”

Abstract

ABSTRACT Mealybugs (Hemiptera, Coccoidea, Pseudococcidae) are plant sap-sucking insects that have within their body cavities specialized cells containing prokaryotic primary endosymbionts (P-endosymbionts). The P-endosymbionts have the unusual property of containing within their cytoplasm prokaryotic secondary endosymbionts (S-endosymbionts) [C. D. von Dohlen, S. Kohler, S. T. Alsop, and W. R. McManus, Nature (London) 412:433-436, 2001]. Four-kilobase fragments containing 16S-23S ribosomal DNA (rDNA) were obtained from the P-endosymbionts of 22 mealybug species and the S-endosymbionts of 12 representative species. Phylogenetic analyses of the P-endosymbionts indicated that they have a monophyletic origin and are members of the β-subdivision of the Proteobacteria ; these organisms were subdivided into five different clusters. The S-endosymbionts were members of the γ-subdivision of the Proteobacteria and were grouped into clusters similar to those observed with the P-endosymbionts. The S-endosymbiont clusters were distinct from each other and from other insect-associated bacteria. The similarity of the clusters formed by the P- and S-endosymbionts suggests that the P-endosymbionts of mealybugs were infected multiple times with different precursors of the S-endosymbionts and once the association was established, the P- and S-endosymbionts were transmitted together. The lineage consisting of the P-endosymbionts of mealybugs was given the designation “ Candidatus Tremblaya” gen. nov., with a single species, “ Candidatus Tremblaya princeps” sp. nov. The results of phylogenetic analyses of mitochondrial DNA fragments encoding cytochrome oxidase subunits I and II from four representative mealybug species were in agreement with the results of 16S-23S rDNA analyses, suggesting that relationships among strains of “ Candidatus T. princeps” are useful in inferring the phylogeny of their mealybug hosts.

Authors

Thao, MyLo Ly; Gullan, Penny J.; Baumann, Paul

Publication date

2002-07-01

DOI

10.1128/aem.68.7.3190-3197.2002