AUTHOR=López-Madrigal Sergio , Latorre Amparo , Moya Andres , Gil Rosario 

TITLE=The link between independent acquisition of intracellular gamma-endosymbionts and concerted evolution in Tremblaya princeps

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.00642

DOI=10.3389/fmicb.2015.00642

ISSN=1664-302X

ABSTRACT=<p>Many insect species establish mutualistic symbiosis with intracellular bacteria that complement their unbalanced diets. The betaproteobacterium “<italic>Candidatus</italic> Tremblaya” maintains an ancient symbiosis with mealybugs (Hemiptera: Pseudococcidae), which are classified in subfamilies Phenacoccinae and Pseudococcinae. Most Phenacoccinae mealybugs have “<italic>Candidatus</italic> Tremblaya phenacola” as their unique endosymbiont, while most Pseudococcinae mealybugs show a nested symbiosis (a bacterial symbiont placed inside another one) where every “<italic>Candidatus</italic> Tremblaya princeps” cell harbors several cells of a gammaproteobacterium. Genomic characterization of the endosymbiotic consortium from <italic>Planococcus citri</italic>, composed by “<italic>Ca</italic>. Tremblaya princeps” and “<italic>Candidatus</italic> Moranella endobia,” unveiled several atypical features of the former's genome, including the concerted evolution of paralogous loci. Its comparison with the genome of “<italic>Ca</italic>. Tremblaya phenacola” PAVE, single endosymbiont of <italic>Phenacoccus avenae</italic>, suggests that the atypical reductive evolution of “<italic>Ca</italic>. Tremblaya princeps” could be linked to the acquisition of “<italic>Ca</italic>. Moranella endobia,” which possess an almost complete set of genes encoding proteins involved in homologous recombination. In order to test this hypothesis, we performed comparative genomics between “<italic>Ca</italic>. Tremblaya phenacola” and “<italic>Ca</italic>. Tremblaya princeps” and searched for the co-occurrence of concerted evolution and homologous recombination genes in endosymbiotic consortia from four unexplored mealybug species, <italic>Dysmicoccus boninsis</italic>, <italic>Planococcus ficus</italic>, <italic>Pseudococcus longispinus</italic>, and <italic>Pseudococcus viburni</italic>. Our results support a link between concerted evolution and nested endosymbiosis.</p>