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Thesis started november 1st, 2018 - Defended in november, 2019 19th
Funding: PIA RAPSODYN
Direction: Nathalie Nesi

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Abstract:

One of the current challenges in plant breeding is to ensure optimized and stable production in low-input cropping systems under fluctuating environments. The observed phenotype results from the expression of the effects of the genotype and the environment in addition to genotype × environment interactions (G×E). Breeding for varieties that are stable/adapted to a wide range of environments or, on the opposite, specifically adapted to targeted environments, requires understanding and exploiting the G × E interactions. In this context, this thesis work aimed at answering the following questions: i) what are the main abiotic factors limiting seed yield in winter oilseed rape, ii) how can these factors be used to define environmental typologies that make it possible to characterize and cluster environments to decompose the G×E interaction, and finally iii) is this envirotyping relevant to characterize the genetic determinants controlling the G×E ?

A strategy based on the characterization and analysis of a network of 47 trials spread over the main rapeseed growing areas in France and conducted under contrasting nitrogen nutrition regimes, was used to identify the factors limiting seed yield in rapeseed and to cluster the trials into envirotypes. Subsequently, a genome wide association study was conducted on 173 winter oilseed rape genotypes tested within this network in order to identify the QTL that control seed yield and the G×E interaction. Stable and specific QTL were identified according to envirotypes. The interest of this approach and the results obtained are discussed, particularly with the regards to their potential use in breeding programs.