Different properties of the inward rectifying potassium conductance of aleurone protoplasts from dormant and non-dormant barley grains |
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Authors: | Bert Van Duijn Marcel T Flikweert Freek Heidekamp Mei Wang |
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Institution: | (1) Department of Physiology, Leiden University, P.O. Box 9604, 2300 RC Leiden, The Netherlands;(2) Department of Anaesthesiology, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands;(3) Institute of Molecular Plant Sciences, Clusius Laboratory, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands;(4) Department of Plant Biotechnology, Center for Phytotechnology RUL/TNO, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands |
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Abstract: | Isogenic dormant and non-dormant barley grains provide a useful system to study the molecular mechanisms of grain dormancy and the role of plant hormones in this process. As ion fluxes are associated with dormancy-related plant hormone responses, we compared the properties of the inward rectifying potassium conductance in aleurone protoplasts isolated from dormant and non-dormant Triumph grains and in germinating Himalaya grains. Maximal conductance, voltage dependency of steady-state activation, activation and deactivation kinetics were studied in the whole-cell patch-clamp configuration. Activation and deactivation time courses were single exponential. No differences in the above described properties were found between the protoplasts isolated from non-dormant Triumph and Himalaya grains. However, the maximal conductance (corrected for cell size) in protoplasts from dormant Triumph grains was much smaller (65%), and activation time constants were much larger as compared to protoplasts from non-dormant grains. No differences were found in the deactivation kinetics in the three different types of protoplasts. The half-maximal activation potential was slightly more negative in protoplasts from dormant grains than from non-dormant grains. |
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Keywords: | dormancy aleurone inward rectifying K+ channels potassium patch-clamp barley |
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