Maxime Durand
University of Helsinki
I am an ecophysiologist who develops a research focused on understanding plant function at the leaf, individual and ecosystem level in response to dynamic environments. While many physiological processes are typically studied under constant, steady conditions, I specialize in the dynamic response of plants to their ever-changing natural environment. I completed my PhD in 2019 in France, regarding the determinisms of water-use efficiency under drought. Since then, I authored 18 publications, 12 as first author. After my PhD, I joined the Canopy Spectral Ecology and Ecophysiology group at the University of Helsinki. There, I built a network of international collaborators and developed a research focused on plant responses to light fluctuations, and how they are created according to canopy architecture.
Title of presentation
Caught between two states: the compromises involved in acclimation to fluctuating irradiance.
Authors
M. DURAND, X. ZHUANG, Y. SALMON, Z. R. STANGL, and T. M. ROBSON
Organismal and Evolutionary Biology (OEB), Viikki Plant Science Centre (ViPS), Faculty of Biological and Environmental Sciences, University of Helsinki, 00014, Finland.
Abstract
Plants canopies are ever-changing environments where conditions are never steady. It necessitates dynamic adjustments of stomata and photosynthesis to both long and short light fluctuations (sunflecks); now recognized as an important driver of carbon uptake. Investigating long sunflecks (30 min) on Fagus sylvatica in the field, we found sun leaves responded faster to a sunfleck than shade leaves, despite shade leaves completing full induction in a shorter time due to their much smaller photosynthetic capacity. Our results highlight the ubiquity of sunflecks in driving photosynthesis, not only in lower-canopy leaves where shade dominates, but particularly in the upper canopy where longer sunflecks are more common due to canopy openness. Under short (<1 min) sunflecks, stomata are too slow to dynamically track changes in irradiance, and thermal imagery of Arabidopsis thaliana showed a four times greater leaf transpiration due to high stomatal conductance relative to steady conditions. Their leaves were also thinner but maintained photosynthetic capacity. Altogether our findings underline that naturally fluctuating irradiance creates conflicting acclimation cues for photosynthesis and transpiration between/within individuals. Thus understanding how sunflecks govern ecosystem carbon and water dynamics could provide the opportunity to play both sides and mitigate global changes while improving food security.