Our current researches in the laboratory are focusing on long distance water transport in plants, mostly trees. Our main interest is the understanding of xylem cavitation, its relation to xylem anatomy and its implication for tree resistance to drought stress. More recently we have developed researches on leaf aquaporins.
· Techniques for measuring xylem vulnerability to cavitation
Several techniques have been developed to assess xylem cavitation (The ‘Sperry’ Hydraulic, Acoustic, Cryo-SEM, Centrifuge etc..). Each technique has its limits and advantages. We aim at identifying the performances of these techniques, their possible biases and at developing more efficient ones.
· Genotypic and phenotypic variability of xylem vulnerability to cavitation in trees
Between species, it is well established that differences in vulnerability to cavitation are huge. Within a species this information is still very scarce. With our new centrifuge technique we are now able to document cavitation resistance on a large number of samples. We aim at answering the following questions:
· How cavitation resistance varies with environmental growing conditions (phenotypic plasticity and acclimatation)?
· How cavitation resistance varies between provenances or genotypes. How this genotypic variability correlates with overall tree resistance to drought stress? Is cavitation resistance a sound criterion for screening genotypes for enhanced drought resistance?
· What are the molecular and genetic basis of cavitation? A big deal, but we are working on it…
· Biophysical and functional constraints in xylem design
In trees, xylem tissue has to satisfy three fundamental functions: long distance water transport, mechanical support and storage of water and carbohydrates. Our goal is to understand how xylem structure (anatomy) is design to cope with these different functions. We aim at understanding the relations between xylem resistance to water and freeze stress induced cavitation, the mechanical resistance of conduit walls and their construction cost. We are currently focusing on conifer species for their relative simple xylem structure. We have documented the following species. We will be happy to look at more conifer species, just send them to us!
· Implication of aquaporins in the control of leaf hydraulic conductivity
Water channels (aquaporins) are responsible for water flows through plasma-membranes in living cells. The role of aquaporins in the control of root hydraulic conductance is now well established. We are focusing on their implication on the control of leaf hydraulic conductance and their regulation by environmental factors such at light, temperature and water stress. We are combining ecophysiological and molecular approaches in this study. Our goal is to better understand how leaf hydraulics is regulated in planta and can adjust to fluctuations in the environmental conditions.