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Abscisic Acid transport coefficients of phaseolus root systems
E L Fiscus1, F R Stermitz, L G Amoros
1United States Department of Agriculture-Agricultural Research Service, Crops Research Laboratory, Colorado State University, Fort Collins, Colorado 80523.
Plant Physiology
|June 1, 1982
Summary
Transport coefficients for abscisic acid (ABA) in Phaseolus vulgaris root systems were measured. ABA exhibited high reflection and moderate diffusive coefficients, indicating efficient root uptake and transport.
Area of Science:
- Plant Physiology
- Biophysics
- Agricultural Science
Background:
- Abscisic acid (ABA) is a crucial plant hormone regulating various physiological processes, including root function.
- Understanding ABA transport mechanisms in plant roots is essential for crop improvement and stress management.
Purpose of the Study:
- To quantify the diffusive and convective transport coefficients of abscisic acid (ABA) in Phaseolus vulgaris cv. Ouray root systems.
- To elucidate the role of root tissues in ABA uptake and translocation.
Main Methods:
- Measurement of convective (reflection coefficient, sigma) and diffusive (omega) transport coefficients for ABA.
- Application of ABA to root systems and analysis of exudates over time to determine steady-state concentrations.
Main Results:
- The convective coefficient (sigma) for ABA was determined to be 0.96, indicating high reflection and efficient retention within the root system.
- The diffusive coefficient (omega) for ABA was measured at 1.44 x 10(-11) mole/cm²/s/bar.
- Steady-state ABA concentrations in root exudates were reached after a minimum of three hours, suggesting slow binding site saturation or xylem tissue equilibration.
Conclusions:
- Phaseolus vulgaris roots exhibit efficient convective transport of ABA, with a reflection coefficient close to unity.
- The diffusive transport of ABA is moderate, influenced by binding and equilibration processes within root tissues.
- ABA transport is a dynamic process involving interactions with root tissues, impacting its translocation to the xylem and subsequent physiological effects.
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