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pH-regulated leaf cell expansion in droughted plants is abscisic acid dependent
1Biological Sciences Department, Institute of Environmental and Natural Sciences, Lancaster University, Bailrigg, Lancaster LA1 4YQ, United Kingdom.
Plant Physiology
|December 10, 1998
Summary
Drought stress increases barley xylem sap pH, signaling reduced leaf growth. This pH change, mediated by abscisic acid (ABA), impacts leaf elongation rates in plants.
Area of Science:
- Plant Physiology
- Plant Biochemistry
- Drought Stress Physiology
Background:
- Soil water content directly influences plant growth rates.
- Xylem sap pH changes have been observed during drought conditions.
Purpose of the Study:
- To investigate the role of xylem sap pH as a drought stress signal.
- To determine the mechanism by which pH affects leaf elongation.
Main Methods:
- Measuring barley leaf elongation rates under varying soil moisture.
- Analyzing xylem sap pH and abscisic acid (ABA) levels.
- Feeding artificial xylem sap of controlled pH to derooted seedlings.
- Utilizing ABA-deficient mutants to assess ABA's role.
Main Results:
- Leaf elongation rates decreased as soil water content and xylem sap pH increased.
- Artificial sap pH directly inhibited leaf elongation, independent of light or ABA concentration.
- ABA-deficient mutants showed no pH-dependent reduction in leaf elongation, which was restored by exogenous ABA.
Conclusions:
- Increased xylem sap pH functions as a drought signal in barley.
- This pH-mediated signaling pathway reduces leaf elongation via an ABA-dependent mechanism.