The primary processes of photosystem II in purified guard-cell protoplasts and mesophyll-cell protoplasts fromCommelina communisL.
✍ Scribed by Michael F. Hipkins; Peter J. Fitzsimons; Jonathan D. B. Weyers
- Publisher
- Springer-Verlag
- Year
- 1983
- Tongue
- English
- Weight
- 749 KB
- Volume
- 159
- Category
- Article
- ISSN
- 0032-0935
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✦ Synopsis
Guard-cell protoplasts were isolated by enzymic digestion of the epidermis peeled from the abaxial surface of leaves from Commelina communis L. The protoplasts were separated from mesophyll-cell protoplasts and other contaminants by density-gradient centrifugation, and the purity of the preparations carefully and quantitatively assessed by light microscopy. The preparations of guard-cell protoplasts were then compared with mesophyll-cell protoplasts in terms of the activity of photosystem II as assessed by a) the light-induced evolution of oxygen under both steady-state and flashing light and b) the characteristics of photosystem-II chlorophyll fluorescence. In all experiments, clear photosystem-II activity was found in guard-cell protoplasts, although some subtle distinctions between guard-cell and mesophyll-cell protoplasts were found. The contribution of any contamination by mesophyll-cell chlorophyll to guard-cell-protoplast signals was estimated to be less than 3% in all cases. The results indicate that photosystem II is present and active in guard cells of Commelina.