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ESTABLISHMENT : University of Lille, Faculty of Sciences and Technologies

Laboratory(ies) of affiliation : UMRT INRAE 1158 BioEcoAgro

Scientific field, Speciality: DS10 | Food Biotechnology, Food Science, Physiology

Thesis director: Gagneul, David, Lecturer, david.gagneul@univ-lille.fr

Co-supervisor (non HDR): Quéro, Anthony, Lecturer, anthony.quero@u-picardie.fr

Planned (co)-funding : Région Hauts-de-France (in progress, 50%) et ED 104 SMRE (in progress, 50%)

Title of the thesis : Implication of swertisin and swertiajaponin in cold stress tolerance of flax (Linum usitatissimum L.)

THESIS SUBJECT

Global warming is associated with a progressive increase in the frequency of climatic accidents. In order to mitigate this evolution and maintain an agricultural production that meets the needs of our societies, it will be necessary to modify the cultivation practices of field crops. To adapt to tomorrow's environment and ensure the ecological and environmental transition, the use of new varieties represents a relevant approach. Thus, for fiber flax, a species of regional interest, the creation of winter varieties is a judicious solution. Sown at the end of September, winter flax takes root during the fall and is well established in the spring when vegetation resumes. Its well-developed root system allows it to draw water from deep within the soil and to be more tolerant than spring flax during unfavorable spring rainfall (as in 2022). Also, its earlier maturity than spring flax, allows it to be pulled out earlier (beginning of June) and to be less exposed to the dry conditions of the summer.

Despite these advantages, the number of available winter flax varieties is still limited and the lack of information on the mechanisms involved in cold tolerance in flax slows down varietal selection. Thus, the lack of biomarkers restricts breeders in their approach and the breeding of these varieties relies today on empirical methods. Two potential markers for winter wheat have recently been identified: C-glycoside flavones. The objective of this thesis is to definitively determine the role of these molecules in cold tolerance and thus provide breeders with tools to assist in selection.

A candidate gene, LuOMT1, whose product would be involved in the last step of the synthesis of these flavone C-glycosides, has been recently identified and cloned in the laboratory. The first step will be to validate the involvement of the product of this gene in the synthesis of flavone C-glycosides (biochemical role). The recombinant protein will be produced in different heterologous systems, purified and its catalytic parameters determined. Then, through genome editing of spring and winter flax varieties (overexpression or gene silencing), the involvement of the molecules in cold tolerance will be validated (physiological role). The genetic modifications induced should lead to metabolic modifications and the impact of these modifications will be apprehended through the monitoring of acclimatization and cold tolerance of genetically modified lines.

Expected date of recruitment: october 1st 2023

Contact: david.gagneul@univ-lille.fr and anthony.quero@u-picardie.fr