Habilitation to do Research Supervision (HDR)

Thurday, june 17, 2021 2pm
(videoconference)
Campus de la Gaillarde

Transcriptional variability: a missing link between the genotype and phenotype?
Jury:
Olivier Hamant, DR INRAE, ENS de Lyon, Lyon (Rapporteur)
Anne Krapp, DR INRAE, IJPB, Versailles (Rapportrice)
François Parcy, DR CNRS, CEA Grenoble, Grenoble (Rapporteur)
Jose Jimenez-Gomes, DR INRAE, IJPB, Versailles (Examinateur)
Philippe Nacry, DR INRAE, BPMP, Montpellier (Président du Jury)
Abstract:
I am fascinated by fundamental questions such as the link between genotypes and phenotypes mediated by transcriptional regulation. Epigenetics and chromatin modifications are of strong importance in the link between genotypes and phenotypes. This is why I joined the group of Vincent Colot for my PhD to understand the role of epigenetics on development in plants. Toward the end of my PhD, I became interested in the role of chromatin in plant’s responses to the environment. I thus joined the group of Phil Wigge to understand the role of chromatin in controlling the ambient temperature transcriptome. While I was doing my Phd and Postdoctoral research, I always felt I was missing one important aspect in the link between genotype and phenotype: transcriptional variability, or noise. It is the fact to observe phenotypic or transcriptional differences between genetically identical individuals that are in the same environment. It is now known that noise is an important part of transcriptional regulation, and that transcriptional noise is beneficial under stress conditions. I thus decided to join the group of James Locke in order to characterise, at a genome-wide scale, the level of gene expression variability in plants.
I am now a CRCN in the group of Antoine Martin at BPMP, where I combine my interest for transcriptional variability, the response of plants to the environment, and my skills in genome-wide approaches. I study the regulation of transcriptional variability and its consequences in the context of nitrate nutrition in plants.
Nitrate nutrition is a perfect model to explore the role of gene expression variability in the response to environment for multiple reasons: (i) I observed that several genes involved in the response to nitrate exhibit high inter-individual gene expression variability. This is the case for NRT2.1, a high affinity nitrate transporter, which will be one of the main candidate gene analyzed in this project. (ii) Nitrate concentration displays strong spatial and temporal fluctuation in the wild. In this context, we can wonder if gene expression variability for key genes of nitrate nutrition could be involved in a bet-hedging strategy. (iii) A lot of work has been done to understand how NRT2.1, and the response to nitrate, is regulated at the transcriptional level, giving rise to the development of regulatory networks. This large amount of knowledge will be essential to analyze the role of inter-individual transcriptional variability in the response to nitrate. I will use a combination of transcriptomic, epigenomic, microscopy and targeted functional studies  to characterise how gene expression variability is regulated and its functional relevance. Transcriptional variability is a recent research field and the project will shed light on its role in the genotype to phenotype link.