Abstract
A technique is described for mechanically isolating metabolically active individual spongy mesophyll cells from the Crassulacean acid metabolism plant, Sedum telephium. Mature leaves are selected at about 2 PM when acidity is low, and three different media are used to reduce the problem of leaf acidity and to maintain isotonic conditions. The upper and lower epidermis is peeled from chilled leaves and the leaves are suspended in a buffered “soaking medium,” then gently ground with a mortar and pestle. Cells and debris are separated using a “washing medium,” with cells being filtered through a 136 micron net and collected on an 80 micron net. Cells then are suspended in a “cell suspension medium” and concentrated by centrifugation. Approximately 2 hours are required for the isolation procedure, and activity in CO2 fixation is constant for up to 4 hours after isolation. Microscopic examination shows about 65% of the isolated cells appear intact and unplasmolyzed and are similar to leaf msophyll cells. The yield of cells on a leaf chlorophyll basis is about 1%. A light micrograph of the isolated cells is given.
The isolated cells upon addition of phosphoenolpyruvate, 2-phosphoglycerate, and ribulose-1, 5-diphosphate fix CO2 as rapidly as intact leaves; however, without exogenous substrate the cells only fix CO2 between 10 and 20% of intact leaves. The temperature and pH optima for cellular CO2 fixation in the presence of phosphoenolpyruvate is 35 to 45 C and 7.5 to 9.0, respectively. The light and dark portions of CO2 fixation with the isolated cells are considered in relation to a scheme for net CO2 fixation by Crassulacean acid metabolism plants.
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- Bassham J. A., el-Badry A. M., Kirk M. R., Ottenheym H. C., Springer-Lederer H. Photosynthesis of isolated chloroplasts. V. Effect of fixation rate and metabolite transport from the chloroplasts caused by added fructose-I,6-diphosphatase. Biochim Biophys Acta. 1970 Dec 8;223(2):261–274. doi: 10.1016/0005-2728(70)90183-0. [DOI] [PubMed] [Google Scholar]
- Bradbeer J. W., Ranson S. L., Stiller M. Malate Synthesis in Crassulacean Leaves. I. The Distribution of C in Malate of Leaves Exposed to CO(2) in the Dark. Plant Physiol. 1958 Jan;33(1):66–70. doi: 10.1104/pp.33.1.66. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Brandon P. C. Temperature features of enzymes affecting crassulacean Acid metabolism. Plant Physiol. 1967 Jul;42(7):977–984. doi: 10.1104/pp.42.7.977. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chen T. M., Brown R. H., Black C. C. Photosynthetic CO(2) Fixation Products and Activities of Enzymes Related to Photosynthesis in Bermudagrass and Other Plants. Plant Physiol. 1971 Feb;47(2):199–203. doi: 10.1104/pp.47.2.199. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Edwards G. E., Black C. C. Isolation of Mesophyll Cells and Bundle Sheath Cells from Digitaria sanguinalis (L.) Scop. Leaves and a Scanning Microscopy Study of the Internal Leaf Cell Morphology. Plant Physiol. 1971 Jan;47(1):149–156. doi: 10.1104/pp.47.1.149. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hatch M. D., Slack C. R. Photosynthesis by sugar-cane leaves. A new carboxylation reaction and the pathway of sugar formation. Biochem J. 1966 Oct;101(1):103–111. doi: 10.1042/bj1010103. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jensen R. G. Activation of CO 2 fixation in isolated spinach chloroplasts. Biochim Biophys Acta. 1971 Jun 15;234(3):360–370. doi: 10.1016/0005-2728(71)90203-9. [DOI] [PubMed] [Google Scholar]
- Kortschak H. P., Hartt C. E., Burr G. O. Carbon Dioxide Fixation in Sugarcane Leaves. Plant Physiol. 1965 Mar;40(2):209–213. doi: 10.1104/pp.40.2.209. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pucher G. W., Leavenworth C. S., Ginter W. D., Vickery H. B. Studies in the Metabolism of Crassulacean Plants: The Diurnal Variation in Organic Acid and Starch Content of Bryophyllum calycinum. Plant Physiol. 1947 Oct;22(4):360–376. doi: 10.1104/pp.22.4.360. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Saltman P., Kunitake G., Spolter H., Stitts C. The Dark Fixation of CO(2) by Succulent Leaves: The First Products. Plant Physiol. 1956 Nov;31(6):464–468. doi: 10.1104/pp.31.6.464. [DOI] [PMC free article] [PubMed] [Google Scholar]