Jeroen D M Schreel1,2, Craig Brodersen3, Thomas De Schryver4, Manuel Dierick4, Adriana Rubinstein3, Koen Dewettinck5, Matthieu N Boone4, Luc Van Hoorebeke4, Kathy Steppe1. 1. Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Gent, Belgium. 2. Institute of Environment, Department of Biological Sciences, Florida International University, Miami, FL, USA. 3. School of the Environment, Yale University, New Haven, CT, USA. 4. UGent Centre for X-ray Tomography (UGCT) - Radiation Physics Group, Department of Physics & Astronomy, Ghent University, Proeftuinstraat 86, 9000 Gent, Belgium. 5. Food Structure & Function Research Group, Department of Food Technology, Safety and Health, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Gent, Belgium.
Abstract
BACKGROUND AND AIMS: Foliar water uptake has recently been suggested as a possible mechanism for the restoration of hydraulically dysfunctional xylem vessels. In this paper we used a combination of ecophysiological measurements, X-ray microcomputed tomography and cryo-scanning electron microscopy during a drought treatment to fully evaluate this hypothesis. KEY RESULTS: Based on an assessment of these methods in beech (Fagus sylvatica L.) seedlings we were able to (1) confirm an increase in the amount of hydraulically redistributed water absorbed by leaves when the soil water potential decreased, and (2) locate this redistributed water in hydraulically active vessels in the stem. However, (3) no embolism repair was observed irrespective of the organ under investigation (i.e. stem, petiole or leaf) or the intensity of drought. CONCLUSIONS: Our data provide evidence for a hydraulic pathway from the leaf surface to the stem xylem following a water potential gradient, but this pathway exists only in functional vessels and does not play a role in embolism repair for beech.
BACKGROUND AND AIMS: Foliar water uptake has recently been suggested as a possible mechanism for the restoration of hydraulically dysfunctional xylem vessels. In this paper we used a combination of ecophysiological measurements, X-ray microcomputed tomography and cryo-scanning electron microscopy during a drought treatment to fully evaluate this hypothesis. KEY RESULTS: Based on an assessment of these methods in beech (Fagus sylvatica L.) seedlings we were able to (1) confirm an increase in the amount of hydraulically redistributed water absorbed by leaves when the soil water potential decreased, and (2) locate this redistributed water in hydraulically active vessels in the stem. However, (3) no embolism repair was observed irrespective of the organ under investigation (i.e. stem, petiole or leaf) or the intensity of drought. CONCLUSIONS: Our data provide evidence for a hydraulic pathway from the leaf surface to the stem xylem following a water potential gradient, but this pathway exists only in functional vessels and does not play a role in embolism repair for beech.
Authors: Brendan Choat; Markus Nolf; Rosana Lopez; Jennifer M R Peters; Madeline R Carins-Murphy; Danielle Creek; Timothy J Brodribb Journal: Tree Physiol Date: 2019-01-01 Impact factor: 4.196