Guard Cell Regulation of Stomatal Response: Chloroplast Function and Abscisic Acid Metabolism in Guard Cells of Commelina Communis and Vicia Faba
Techniques were evaluated for obtaining viable, purified guard cells by sonication of epidermal peels of Vicia faba L. and by treatment at pH 4 of epidermal peels of Commelina communis L. The guard cells were free of mesophyll cells and chloroplasts and of living epidermal cells as shown by fluorescence microscopy and uptake of neutral red. The guard cells of Vicia were 98% free of non-guard cell chlorophyll. These cells were used to measure the light-induced electrochromic absorbance changes indicative of the electrical component of the high energy state in guard cell chloroplasts. The guard cells exhibited DCMU-sensitive photosystem 2 activity, DBMIB-sensitive electron transport and DCCD-sensitive relaxation of the electric field associated with photophosphorylation. These results indicate that guard cell chloroplasts, although reported to lack Calvin-Benson cycle enzymes, are photosynthetically competent with respect to electron transport and photophosphorylation.
University of Illinois - Urbana-Champaign
Networked Digital Library of Theses and Dissertations
University of Illinois at Urbana-Champaign