Acknowledgements
This material is based upon work supported by the U.S. Department of Energy (DOE), Office of Science, Office of Biological and Environmental Research (BER), Biological System Science Division (BSSD), Early Career Research Program under Award number FP00007421 to Lawrence Berkeley National Laboratory. This work was also supported as part of the DOE Joint BioEnergy Institute through contract DE-AC02-05CH11231 to Lawrence Berkeley National Laboratory. A portion of this research was performed on project awards (10.46936/cpcy.proj.2019.50708/60006566 and 10.46936/expl.proj.2019.51078/60006676) from the Environmental Molecular Sciences Laboratory, a DOE Office of Science User Facility sponsored by the BER program under Contract No. DE-AC05-76RL01830. We would like to acknowledge extensive project guidance from Eoin Brodie and Christina Wistrom for the maintenance and establishment of our poplar trees at the UC Berkeley Oxford Greenhouse. In addition, we would like to acknowledge Thomas Powell for practical advice on leaf water potential measurements and the helpful discussions on cell wall elasticity and plant drought stress responses.