Thursday, December 5, 2024 - Thesis defense - Kilian Dehlouz

Kilian DEHLOUZ

Thesis presented to obtain the degree of Doctor of the University of Bordeaux - Specialization : Agronomic Sciences

Team FDFE

Thursday, December 5, 2024 - 9:30am - Amphithéâtre Colette & Josy Bové - Campus INRAE Villenave d'Ornon
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Résumé : The strawberry reproduces both sexually (flowering) and asexually (stolons). These two modes, although antagonistic, are agriculturally important: flowering affects fruit yield, while stolons enable the propagation of varieties. This competition occurs particularly at the level of axillary buds (AxB), which develop either into branches that can terminate in an inflorescence or into stolons. Understanding the genetic network controlling the development of AxB is crucial, as it influences both fruit yield and strawberry plant production. The objective of my thesis is to elucidate the molecular mechanisms involved in the balance between sexual and asexual reproduction in diploid strawberry through three main questions:
-What are the molecular players involved in the differentiation of AxB into a stolon or a branch, and can a molecular signature of the AxB be associated with its differentiation stage and fate? Comparative and predictive transcriptomic analyses on AxB collected from different genotypes, at different developmental stages, and at different positions on the plant highlighted key players and signature genes related to the fate and differentiation status of AxB.
-What are the molecular players involved in the fate of the axillary bud, whether it becomes a stolon or a branch? A comparative transcriptomics approach on morphologically undifferentiated AxB allowed the identification of biological processes and a shortlist of genes potentially involved in this balance.
-Do modifications in the expression of candidate genes alter the balance between sexual and asexual reproduction? Genome editing approaches using CRISPR were applied to two genes of interest to evaluate the impact of the loss of function of these genes on the balance between sexual and asexual reproduction.

This thesis has helped to complete the regulatory network controlling the fate and differentiation of AxB, and thus the balance between sexual and asexual reproduction in strawberries, and has identified potential targets for the improvement of cultivated strawberry varieties.

Direction : Mme Amélia GASTON

Jury members

Mme Sandra CORTIJO, Chargée de Recherche, Institut des Sciences des Plantes de Montpellier, Rapporteuse
M. Soulaiman SAKR, Professeur des universités, Institut Agro Rennes-Angers, Rapporteur
Mme Valérie SCHURDI-LEVRAUD, Professeure des universités, Université de Bordeaux, Examinatrice
Mme Amélia GASTON, Chargée de Recherche, INRAE Nouvelle-Aquitaine Bordeaux, Directrice de thèse