Public Thesis defense - LIBST

Genetic variability of the expression of plasma membrane aquaporins in maize leaves: from eQTLs to characterization of cis- and trans-acting regulatory factors by Laurie MAISTRIAUX

Pour l’obtention du grade de docteur en sciences agronomiques et ingénierie biologique

Aquaporins are channels facilitating water movements through biological membranes. In plants, they are involved in many essential processes (cellular homeostasis, tissue hydraulic...) and are key players of the response to environmental cues. While the varying expression patterns of aquaporin genes have been described across organs, developmental stages and stress conditions, the elucidation of the responsible regulation remains elusive. Hence, this work aimed to shed light on the expression variability of five plasma membrane aquaporin (PIP) genes in maize leaves, and its genetic causes, via eQTL (expression quantitative trait locus) mapping across a 252-hybrid diversity panel.

The implemented genome-wide association study mapped many eQTLs, either close to, or distant from, the cognate PIP genes. A careful scrutiny of the results, including the evaluation of potential technical bias sources, strengthened the selection of eQTLs for further functional validation. Ultimately, two eQTLs associated with PIP2;5 expression variation were characterized. Genomic sequence comparison and in vivo reporter assay allowed attributing, at least partly, the local eQTL to a transposon-containing polymorphism in the PIP2;5 promoter. Further data, however, unveiled a more complex regulation depending on cell types, organs and environmental conditions that likely fine-tunes PIP2;5 expression in planta. The preliminary investigation on the candidate NAC24 transcription factor identified within a distant eQTL led to promising results, including the PIP2;5 transactivation in the presence of NAC24 in vivo. This work thus opened opportunities regarding the molecular elucidation of PIP gene regulation, and its possible integration into larger networks regulating physiological and stress-adaptation processes.

Jury members :

• Prof. François Chaumont (UCLouvain), supervisor
• Prof. Bernard Hallet (UCLouvain), chairperson
• Prof. Henri Batoko (UCLouvain), secretary
• Dr. François Tardieu (LEPSE, Montpellier (INRAE), France)
• Dr. Clémentine Vitte (Génétique Quantitative et Evolution – Le Moulon (CNRS), France)
• Prof. Xavier Draye (UCLouvain)
• Prof. Marc Boutry (UCLouvain)

Pay attention :

The public defense of Laurie Maistriaux scheduled for Wednesday 27 January at 16:15 will take place in the form of a video conference Teams

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