Evolution of bacterial endosymbiosis in insects: the case of Serratia symbiotica in aphids
(2019) Inter American University of Puerto Rico — Location: Barranquitas, USA (6.September.2019)
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- Abstract
- Serratia symbiotica, one of the most frequent symbiont found in aphids, is a valuable symbiont candidate for studying the evolution of bacterial mutualism in insects. Indeed, this bacterial symbiont species includes a wide diversity of strains whose degree of interdependence with the host may vary considerably. S. symbiotica strains with a free-living capacity on culture media have recently been isolated from aphid species of the genus Aphis. Because these strains may represent a reservoir for the emergence of new associations, they are excellent candidates for understanding how symbiotic associations appear and evolve in nature, especially at the very beginning of the interaction. By performing a series of experiments, we aimed to characterize the nature of the interaction between these cultivable strains and the host aphids. We found that these S. symbiotica strains are able to rapidly colonize the aphid digestive tract following infection, without stimulating genes related to host immunity. Returning on the field, we also observed that these strains are naturally present in the gut of aphids as well in the gut of other insects. We found that the transmission of the cultivable S. symbiotica in aphids is mediated by honeydew and plants. If our results show that these cultivable strains offer immediate protection against parasitoids to infected aphids, they also impose fitness costs. Finally, we also examined the repertoire of genes involved in prokaryote-insect interactions within the cultivable strain CWBI-2.3T. Our preliminary analyses suggest that this strain is capable of expressing a wide range of molecular effectors that are potentially required during the initial stages of host colonization. The genomes of two other cultivable strains have just been sequenced. There is no doubt that these new data should clarify the symbiotic status of cultivable strains and help to understand how they interact with the host insect during the initial stages of the interaction.
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Renoz, F., Pons-Guillouard, I., & Hance, T. (2019). Evolution of bacterial endosymbiosis in insects: the case of Serratia symbiotica in aphids. Inter American University of Puerto Rico, Barranquitas, USA. https://hdl.handle.net/2078.5/248393