Research in the lab
Plants and especially trees are often perceived as almost permanent sculptures of the landscape; their sessile
life style reinforcing the popular misconception of plants having a limited ability to sense and respond to the
world around them. Recent studies suggest a quite different view. Our research on long distance transport
phenomena in plants has uncovered an entirely new suite of dynamic processes that place the hydraulic properties
of the xylem under physiological control. The presence of multiple mechanisms for fast (seconds to minutes) and
spatially distributed (roots, stems and leaves) autonomous flux control allows plants to redistribute and utilize
resources in a highly optimal way across thousands of organs, despite the lack of central processing unit and discrete
nervous system. This ability allows even the largest tree to function as an integrated organism. Our goal is to
understand how the emergent properties of the vascular transport system enables plants to optimize resource utilization
despite temporal and spatial heterogeneity in their environment.
We currently focus on three major research areas where we have evidence for locally controlled physiological processes
that can influence the global redistribution of water fluxes: (1) ion controlled xylem hydraulic resistance; (2)
nutrient controlled root hydraulic properties; and (3) stress controlled adjustment of liquid fluxes in leaves.
Our research builds on and extends our expertise in xylem transport to encompass the exchange surfaces (roots and
leaves) that form the key interfaces between the plant and it environment. It is rare that the full range of
physiological processes involved in resource exchange (nutrient uptake, water uptake and evaporation, phloem transport,
xylem transport) are considered within a single research plan. However, in our opinion, this synthetic approach is key
to understanding the true “systems biology” of plants. A fascinating aspect of this research is that many of the transport
phenomena only become important at the scale of a tree, while they have minimal effect or do not exist in small herbaceous
plants. This underscores the importance of expanding physiological studies beyond current model plants, all the while
cognizant of the opportunities for using molecular tools in addressing questions relating to the biology of trees.