INTRASYM: Genetic requirements in Caballeronia insecticola for intracellular symbiosis inside the gut epithelial cells of phytophagous insects // INTRASYM: Genetic requirements in Caballeronia insecticola for intracellular symbiosis inside the gut epithel

Intracellular symbiosis is important in the biology of extant insects and plants, as a major transition in the evolution of life and for biotechnological applications in plants, yeast and fungi. The PhD project is framed within an overall objective that is to disclose and understand the evolutionary innovations enabling intracellular symbiosis in insects and to apply this understanding to engineer, as a proof of concept, an extracellular association (extra-sym) into a new intracellular symbiosis (intra-sym). The motivation for the IntraSym project is our recent discovery that in the stinkbugs (insect infraorder Pentatomomorpha), closely related species have either extracellular bacterial symbionts in the lumen of the gut (extra-sym) or intracellular symbionts of the same bacterial species located inside the gut epithelial cells (intra-sym). Thus, the Pentatomomorpha provides an ideal and unique framework to identify and compare the genetic determinants for extra-sym and intra-sym in both, the insect host and the bacterial gut symbionts. The INTRASYM PhD project will identify the genetic determinants that are specifically or commonly crucial for extra-sym and intra-sym in the model gut symbiont Caballeronia insecticola. C. insecticola establishes an extra-sym in stinkbugs of the Alydidae and Coreidae families and an intra-sym in species of the Rhyparochromidae family. The PhD candidate will use functional genomics (Tn-seq and RNA-seq), comparative genomics and a candidate gene approach to identify the bacterial adaptations needed for symbiosis in different extra-sym and intra-sym hosts belonging to these stinkbug families. Candidate functions enabling C. insecticola to infect gut epithelial cells or chronically establish in them in intra-sym hosts will be further characterized in depth.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Intracellular symbiosis is important in the biology of extant insects and plants, as a major transition in the evolution of life and for biotechnological applications in plants, yeast and fungi. The PhD project is framed within an overall objective that is to disclose and understand the evolutionary innovations enabling intracellular symbiosis in insects and to apply this understanding to engineer, as a proof of concept, an extracellular association (extra-sym) into a new intracellular symbiosis (intra-sym). The motivation for the IntraSym project is our recent discovery that in the stinkbugs (insect infraorder Pentatomomorpha), closely related species have either extracellular bacterial symbionts in the lumen of the gut (extra-sym) or intracellular symbionts of the same bacterial species located inside the gut epithelial cells (intra-sym). Thus, the Pentatomomorpha provides an ideal and unique framework to identify and compare the genetic determinants for extra-sym and intra-sym in both, the insect host and the bacterial gut symbionts. The INTRASYM PhD project will identify the genetic determinants that are specifically or commonly crucial for extra-sym and intra-sym in the model gut symbiont Caballeronia insecticola. C. insecticola establishes an extra-sym in stinkbugs of the Alydidae and Coreidae families and an intra-sym in species of the Rhyparochromidae family. The PhD candidate will use functional genomics (Tn-seq and RNA-seq), comparative genomics and a candidate gene approach to identify the bacterial adaptations needed for symbiosis in different extra-sym and intra-sym hosts belonging to these stinkbug families. Candidate functions enabling C. insecticola to infect gut epithelial cells or chronically establish in them in intra-sym hosts will be further characterized in depth.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Début de la thèse : 01/10/2026

Contrats ED : Programme blanc GS-BioSphERA

Université Paris-Saclay GS Biosphera - Biologie, Société, Ecologie & Environnement, Ressources, Agriculture & Alimentation

567 Sciences du Végétal : du gène à l'écosystème

Intérêt pour interaction bacterie-insecte et expérience préalable en microbiologie, biologie de l'infection chez les insectes.
Interest in bacteria-insect interactions and prior experience in microbiology, insect infection biology