Public Thesis Defense of Maxime LAURENT - LIBST
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Mapping and characterisation of regulatory variants controlling the expression of aquaporin genes in the mature zone of maize leaves by Maxime Laurent.
Le mardi 11 février 2025 à 16h00 - Jean-Baptiste Carnoy (B.059) – Bâtiment Carnoy - Place Croix du Sud - 1348 Louvain-la-Neuve
Aquaporins (AQP) are channels that modulate the permeability of cell membranes to water and small solutes. In plants, they are involved in numerous physiological and cellular processes, including the hydraulic conductivity of cells, tissues and organs, cell expansion and homeostasis. Given their involvement in such essential roles, they are tightly regulated at multiple levels according to developmental stages, organs, daytime, and in response to environmental stimuli. In this PhD thesis, we were mainly interested in the transcriptional regulation of AQP genes, for which expression profiles under various conditions have been reported. However, little data was available on the specific molecular components involved in their transcription.
Our goal was to discover mechanisms that regulate the transcription of AQP genes in maize leaves under well-watered (WW) and water deficit (WD) conditions. Based on 3’ RNA-seq data from the mature zone of leaves from 254 maize lines grown under both watering conditions (DROPs panel), we identified AQP genes expressed in this region and analysed how their expression varied with soil water availability and genetic background. In addition, we performed a genome-wide association study (GWAS) and mapped expression quantitative trait loci (eQTL) for AQP genes to reveal regions where potential regulators of their expression might be located. All genes present in these eQTLs were retrieved, and those annotated as transcription factors (TFs) were selected for further analyses. We then conducted an enrichment analysis using 45 published gene regulatory networks generated on data from various conditions. Fifteen TFs were found in both eQTLs and enrichment analyses and were selected for further wet lab characterisation using dual-fluorescence and dual-luciferase reporter gene assays. We demonstrated that ZmHSF13 and ZmNAC40 influenced the promoter activities of ZmTIP1;1 and ZmPIP1;3, respectively. Using DAP-seq, we confirmed that ZmHSF13 directly binds to the ZmTIP1;1 promoter. These results contribute to a better understanding of how TFs regulate AQP gene expression and provide important information for further investigation of the AQP gene regulatory network.
Jury members :
Prof. François CHAUMONT (UCLouvain) (Supervisor)
Prof. Michel GHISLAIN (UCLouvain) (Chairperson)
Prof. Charles HACHEZ (UCLouvain) (Secretary)
Prof. Xavier DRAYE (UCLouvain)
Prof. Hilde NELISSEN (VIB-Ghent Univ., Belg.)
Dr. Clémentine VITTE (CNRS, Fr.)
Pay attention: the public defense of Maxime LAURENT will also take place in the form of a videoconference.