Determination of malate levels during the swelling of vacuoles isolated from guard-cell protoplasts
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- Schnabl, H. & Kottmeier, C. Planta (1984) 161: 27. doi:10.1007/BF00951456
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A method for the preparation of vacuoles from guard cells ofVicia faba L. is described. Vacuoles were released from guard-cell protoplasts by osmotic shock and purified on a Ficoll gradient. Contamination of the vacuoles was examined by assaying marker enzymes, such as fumarase, glucose-6-phosphate dehydrogenase, phosphofructokinase, acid phosphatase and mannosidase. Potassium ions in the incubation medium caused increases in the volume of the vacuoles by a factor of about 2.6, while the malate level remained unchanged. In contrast, malate synthesis was stimulated during the swelling phase when complete guard-cell protoplasts were exposed to K+. The possible role of K+ as an efficient osmotic effector is discussed.
Key wordsGuard cell vacuolesMalic acidVacuole (swelling process)Vicia (guard cells)
mesophyll cell protoplast(s)
mesophyll cell vacuole(s)