Léa Monge Waleryszak, PhD
Plant - Microorganism Molecular Interactions
After graduating high school, I took a few personal years (small jobs, one year of medical school from which I mainly remember how to fill atomic orbitals and the use of nuclear physics in medicine, and travelling alone with my backpack through several European countries). I then decided to follow my passion and went to Toulouse University to study biology. After a Bachelor in Biology of Organisms, Populations & Ecosystems (BOPE), that gave me an integrated view of biological mechanisms, I specialized in molecular biology with a MSc in Plants Adaptation, Development & Improvement in presence of Microorganisms (ADAM). Finally, I obtained my PhD degree from the Department of Plant development, Biotic and Abiotic Interactions.
I first studied the regulation of nodule organogenesis by a TALE transcription factor and a lncRNA in the Sinorhizobium meliloti–Medicago truncatula symbiotic system under the supervision of Dr. Andreas Niebel during my MSc.
I then chose to focus on plant-pathogen interactions and secured a fellowship to develop my PhD project with Dr. Laurent Deslandes (Group leader, PhD co-supervisor) and Dr. Valérie Pacquit (Senior lecturer, PhD co-supervisor). My work focused on understanding the extent of bacterial effectors virulence strategies, with a particular focus on the YopJ effector PopP2 from Ralstonia pseudosolanacearum, known to target WRKY proteins. Based on initial Y2H screenings, we identified and characterized three ARID proteins as additional virulence targets of PopP2, demonstrating that PopP2 can target multiple host proteins that present no sequence similarity (ARIDs and WRKYs). Our findings also suggested a manipulation of chromatin remodelling complexes by PopP2 through ARIDs targeting —a virulence mechanism rarely described for effectors from phytopathogenic bacteria. In addition, we showed that XopJ6, a newly identified effector from Xanthomonas campestris that also targets WRKY proteins and is a close homolog of PopP2, also interacts with at least one ARID protein targeted by PopP2. To further explore the potential diversity of PopP2 and XopJ6 targets, I used proximity labelling to identify their proximal proteomes in the model plant Arabidopsis thaliana. As this work is yet to be published, I won’t go into details, but the proteomes revealed exciting additional potential targets, some of which are shared between the two effectors. Overall, we gained insights into the diverse host functions that could be subverted by these effectors, and shed light on specific and shared virulence strategies employed by PopP2 and XopJ6—two effectors from distinct xylem-colonizing bacteria.
