Thesis defence – Université Montpellier
Monday, 15 September 2025 at 2:00 p.m. – Amphi 208
Campus Montpellier SupAgro/INRA de La Gaillarde (2, place P. Viala Montpellier)
Madame Meijie LI
will publicly defend his thesis entitled
Study of the molecular mechanisms that control iron-mobilizing coumarin biosynthesis, trafficking and storage
Reasearch unit : IPSiM – Institut for Plant Sciences of Montpellier
Team: FeROS – Mineral nutrition and oxidative stress
Jury:
- José Le Gourrierec-Gentilhomme, Maître de conférences Université d’Angers, IRHS Angers, Rapporteur
- Massimiiano Corso, Chargé de recherche INRAE, IJPB Versailles, Rapporteur
- Karine Gallardo-Guerrero, Directrice de recherche INRAE, Agroécologie Dijon, Examinatrice
- Helen North, Directrice de recherche INRAE, IJPB Versailles, Examinatrice
- Sébastien Thomine, Directeur de recherche CNRS, I2BC Gif-sur-Yvette, Examinateur
- Enric Zelazny, Chargé de recherche CNRS, IPSiM Montpellier, Examinateur
- Christian Dubos, Directeur de recherche INRAE, IPSiM Montpellier, Directeur de thèse
Abstract
Iron (Fe) is essential for most living organisms. Although Fe is one of the most abundant elements found in soil, it is generally poorly available to plants since it is mainly present in the form of insoluble Fe (hydr)oxides. This is for instance the case in calcareous soils that represent one-third of the world’s cultivated lands. To cope with this poor bioavailability, non-grass species have evolved a reduction-based mechanism to mine Fe from the soil. Recently it has emerged that the secretion of Fe-mobilizing coumarins by the plant roots (via the PDR9 transporter) plays an important role in this process. My PhD project aims at further characterizing the molecular mechanisms that regulate FMCs biosynthesis and transport in order to improve plant iron nutrition, focusing on Arabidopsis thaliana as a model. Three main axes have been developed:
(i) The first part of my PhD thesis focusses on the study of the post-translational regulation of PDR9 activity and aim at determining if phosphorylation and ubiquitination marks on PDR9 can affect its activity and/or cellular/sub-cellular localization.
(ii) The second part of my PhD thesis aims at Identifying novel genes involved in catechol coumarins secretion by a targeted approach. Here, I focus on the characterization of a potential novel transporter of FMCs belonging to the PDR/ABCG family.
(iii) The last part of my PhD thesis aims at precisely determining in planta where coumarins are synthetized in Arabidopsis roots, notably by studying the localization of all know proteins involved in this process, and how this pattern is influenced by a transcription factor belonging to the bZIP family, that represents a novel potential regulator of FMCs biosynthesis and trafficking.
Key words: Iron, Nutrition, Arabidopsis thaliana, Coumarins, PDR9