Thursday April 27, 2023 - Thesis defense - Alexandre Prohaska

Alexandre Prohaska

Team FDFE

Thursday, April 27, 2023 - 2:00 PM - Colette and Josy Bové Amphitheater - Campus INRAE Villenave d'Ornon

Abstract :

Strawberries are a very important economic crop in France, with a turnover of 230 M€ (3rd place for fruit species). Maintaining a stable yield produced from plants subject to climatic hazards in the nursery while reducing inputs is the new challenge facing the strawberry industry. Breeding strawberry cultivars meeting producer’s requirements (stable production in the context of climate change and requiring fewer inputs) and consumers (fruit quality) is therefore an essential challenge. This Cifre thesis is carried out in the framework of a collaboration between Invenio, a French association of producers whose activities are focused on strawberry breeding, and INRAe. Its objective is to contribute to the optimization of the current breeding program through the characterization of the genetic control of key traits and the identification of interesting plant material.This approach has been developed into three themes through the study of three populations genotyped with a 50k SNP chip, including a collection of genetic resources from decades of prospecting, a multi-parental population resulting from crosses of resistant and susceptible cultivars to strawberry powdery mildew, and a biparental population. The first part consists in the implementation of a strategy to improve resistance to strawberry powdery mildew through a broad study of its molecular control by association genetics (GWAS) and QTL mapping approaches, revealing a complex genetic architecture. The characterization of the collection revealed three groups representing well the global and historical genetic diversity described, as well as the calibration of a genomic prediction model validated on other populations. In a second step, the diversity panel was studied extensively for agronomic traits of phenology and architecture, production and fruit quality. The numerous phenotype-genotype associations obtained by GWAS open new perspectives for the understanding of the underlying physiological processes and the development of marker-assisted selection in strawberry, via new genotyping chips. In the third part, the development of a genetic map on a biparental population allowed the identification of SNPs strongly linked to the flowering time and which are colocalized with markers described on genetic resources. The study of this population across Europe allowed to discuss the impact of genotype-environment interactions on flowering and its molecular control. Overall, the results of this thesis shed new light on the diversity and genetic architecture of many agronomic traits of interest. The identification of new genitors and the development of marker-assisted selection methods offer new perspectives for strawberry breeding programs.

Members of the Jury :

Dr. Laurence MOREAU, UMR 0320 Génétique Quantitative et Evolution Le Moulon, INRAE   - Rapportrice
Dr. Charles-Eric DUREL, UMR 1345 Institut de Recherche en Horticulture et Semences (IRHS), INRAE - Rapporteur
Pr. Valérie Schurdi-Levraud - INRAE UMR 1332 Biologie du Fruit et Pathologie (BFP) -Université de Bordeaux, France, examinatrice
Dr Laurent BOUFFIER, UMR 1202 Biodiversité Gènes & Communautés (Biogeco), INRAE , France, examinateur
Dr. Béatrice DENOYES, UMR 1332 Biologie du Fruit et Pathologie (BFP), Directrice de thèse
Dr. Justine PERROTTE, Invenio