© 1987 Heron Publishing—Victoria, Canada
Abscisic acid relations and the response of Populus trichocarpa stomata to leaf water potential
Paul J. Schulte (1, 2) and Thomas M. Hinkley (1)
1. College of Forest Resources, AR-10, University of Washington, Seattle, WA 98195, USA / 2. Department of Biology, University of California-Los Angeles, Los Angeles, CA 90024, USA / Received October 8, 1986
Summary
The role of abscisic acid (ABA) in the mediation of stomatal responses to low leaf water potential was examined with intact
plants and epidermal strips of Populus trichocarpa Torr. & A. Gray. Clones of this species grown under well-watered conditions maintain a high leaf conductance when the foliage
wilts. However, foliar ABA concentration in P. trichocarpa increased manyfold in response to water stress as it did also in P. deltoides Bartr. ex Marsh. and P. trichocarpa × deltoides hybrids. Application of ABA to epidermal strips appeared to cause solute leakage, however stomata of P. trichocarpa remained partially open even when the guard cells were plasmolyzed. Foliar application of ABA induced closure of stomata
in young expanding leaves, but not in fully expanded foliage. Ten days after ABA application, stomata on young leaves were
open at high water potential but closed at low water potential. These characteristics are discussed with respect to wilty
mutants of tomato and potato, which also have stomata unresponsive to leaf wilting.
