Environmental Plant Metabolism

One of the most fascinating challenges mankind will face in the 21st century, and later, is the impact of climate change on the terrestrial biosphere and its repercussions for ecosystems’ carbon (C) balance and sustainability. Ecosystem C balance is the difference between photosynthetic CO2 uptake and respiratory CO2 release. Ecosystems are sustainable when this difference remains positive. Trees and plants in general are key players in maintaining this balance but climate change threatens their durability. Plants are sensitive to their environment, and changes in water availability, temperature, light or nutrients can have dramatic consequences on long-term ecosystem sustainability. My work aims to understand and model the metabolic and physiological responses of plants and ecosystems to abiotic stresses induced by climate change. My general approach to this work is to examine the response of primary metabolism to climate change, model it and integrate it into global scale models. 

My research combines theoretical and empirical approaches to disentangle the complexity of plant metabolic pathway. The empirical approach includes field measurements in temperate and sub-arctic deciduous forest as well as greenhouse environmental manipulation. The theoretical approach includes assessment of current Terrestrial ecosystems models' limitations and design and sensitivity-tests of new parameterizations for respiratory COproduction. 

Modeling Aboveground Plant Respiration

Respiration is recognized as a major actor in Ecosystem Carbon Balance. Respiration may also play an important in regulating Ecosystem sustainability since a direct between Photosynthesis capacity and Respiration rate exits. This project aims to between understand the causes of variations in Plant respiration and to constrain current global change models from the information collected. 

Understanding CO2/O2 respiratory fluxes in the light

Respiratory metabolism is divided in two fundamental parts: the electron transport chain for energy production and the tricarboxylic acid pathway (TCAP) (also known as Krebs cycle). When measuring net CO2 production using a classical gas exchange system (such as LI-6400), only decarboxylations through the TCAP can be measured. As part of my research in Princeton University, I designed and built the first gas exchange system that allows direct, continuous and long-term measurement of gross photosynthesis in entire leaves (Gauthier et al. 2016) using oxygen isotopes. This method involves measuring net O2 production from the change in O2 concentration, and gross production from the rate at which 18O-labeled O2 is generated from 18O labeled water. The O2 produced by photosynthetic water splitting is then registered as a change in d18O of O2. The change of d18O of O2, and O2/N2, are measured to high precision, allowing net and gross production to be accurately assessed at irradiances as low as a few tens of mmol m-2 s-1. This system constitutes an incredible opportunity to study fundamental metabolic pathways and link them to leaf gas exchanges. 

Role of photorespiration on respiratory metabolism

In C3 plants, photorespiration plays an important role in the primary metabolism of leaves. Evidences of its interaction with the respiratory metabolism has been shown. However the origin of this interaction and the environmental control of it remains unclear. This project aims to investigate the origin(s) and consequences of the interaction between photorespiration and respiration on respiratory and nitrogen metabolism in leaves on C3 plants.

Princeton University Python Community

In collaboration with Quentin Caudron, I founded Princeton University Python Community, a python-enthousiats community that aims to expand the utilization of Python as a primary programming language across disciplines. The community includes undergraduates and graduates students, faculty and staff members with any level of expertise. 

Developing low-cost sensors for plant science

"Do all you can with what you have in the time you have in the place you are!" Xolani Nkosi