Two Host Clades, Two Bacterial Arsenals: Evolution through Gene Losses in Facultative Endosymbionts.

Abstract : Bacterial endosymbiosis is an important evolutionary process in insects, which can harbor both obligate and facultative symbionts. The evolution of these symbionts is driven by evolutionary convergence, and they exhibit among the tiniest genomes in prokaryotes. The large host spectrum of facultative symbionts and the high diversity of strategies they use to infect new hosts probably impact the evolution of their genome and explain why they undergo less severe genomic erosion than obligate symbionts. Candidatus Hamiltonella defensa is suitable for the investigation of the genomic evolution of facultative symbionts because the bacteria are engaged in specific relationships in two clades of insects. In aphids, H. defensa is found in several species with an intermediate prevalence and confers protection against parasitoids. In whiteflies, H. defensa is almost fixed in some species of Bemisia tabaci, which suggests an important role of and a transition toward obligate symbiosis. In this study, comparisons of the genome of H. defensa present in two B. tabaci species (Middle East Asia Minor 1 and Mediterranean) and in the aphid Acyrthosiphon pisum revealed that they belong to two distinct clades and underwent specific gene losses. In aphids, it contains highly virulent factors that could allow protection and horizontal transfers. In whiteflies, the genome lost these factors and seems to have a limited ability to acquire genes. However it contains genes that could be involved in the production of essential nutrients, which is consistent with a primordial role for this symbiont. In conclusion, although both lineages of H. defensa have mutualistic interactions with their hosts, their genomes follow distinct evolutionary trajectories that reflect their phenotype and could have important consequences on their evolvability.
Type de document :
Article dans une revue
Genome Biology and Evolution, Society for Molecular Biology and Evolution, 2015, 7 (3), pp.839-855
Liste complète des métadonnées

Littérature citée [106 références]  Voir  Masquer  Télécharger

https://hal.inria.fr/hal-01139507
Contributeur : Marie-France Sagot <>
Soumis le : mardi 23 mai 2017 - 10:36:37
Dernière modification le : jeudi 28 juin 2018 - 14:36:24
Document(s) archivé(s) le : vendredi 25 août 2017 - 00:51:56

Fichier

evv030.pdf
Fichiers éditeurs autorisés sur une archive ouverte

Identifiants

  • HAL Id : hal-01139507, version 1
  • PUBMED : 25714744

Citation

Pierre-Antoine Rollat-Farnier, Diego Santos-Garcia, Qiong Rao, Marie-France Sagot, Francisco J Silva, et al.. Two Host Clades, Two Bacterial Arsenals: Evolution through Gene Losses in Facultative Endosymbionts.. Genome Biology and Evolution, Society for Molecular Biology and Evolution, 2015, 7 (3), pp.839-855. 〈hal-01139507〉

Partager

Métriques

Consultations de la notice

446

Téléchargements de fichiers

66