Corentin MASLARD

Date de soutenance : 20/09/2024 à 9h -

Résumé

"Legumes are grown for their protein-rich seeds, which are used for animal feed or human consumption. Seed legumes do not need nitrogen fertiliser, thanks to their ability to fix atmospheric N2 in symbiosis with soil bacteria (rhizobium) in newly formed root organs called nodules. Legumes therefore play an essential role in the development of more sustainable agriculture and can help mitigate future climate change. However, their sensitivity to environmental stresses, particularly water stress and high temperatures, means that their yields are unstable, which can hamper their development in cropping systems. In the context of climate change, where periods of water stress and high temperatures are more intense and longer, it is necessary to improve the ability of grain legumes to maintain their growth in order to guarantee high levels of productivity. After identifying two soybean genotypes with contrasting root architecture, the two genotypes were placed under control conditions in non-sterile soil and subjected to water deficit and/or heat wave conditions. This thesis highlighted the complex responses of soybean to environmental stresses and revealed several key insights. Water and heat stress significantly influenced the plant’s nutritional balance, with a close correlation observed between water flux intensity and mineral uptake, highlighting the crucial role of water in nutrient transport. The multi-omics approach provided an in-depth understanding of plant metabolism under stress, showing that conditions of combined stress lead to an increase in the potential catabolism and remobilisation of certain nutrient, which is essential for maintaining osmolarity and supporting adaptation to stress. Finally, this research revealed that stress conditions distinctly modify the microbial communities associated with different plant compartments. In particular, root and leaf microbiota responded differently under different stress scenarios, reflecting the nuanced interactions between plants and their associated microbial communities in the face of environmental challenges"

Jury

- Philippe Nacry and Séverine Piutti (rapporteurs)

- Julia Buitink, Kristian Holst Laursen, Manuel Blouin (examiners)

- Christophe Salon (PhD supervisors)

- Mustapha Arkoun and JingJing Peng (guests)

-Marion prudent