Photosynthesis and Increased Production of Protein
Photosynthesis, the use of light energy in the conversion of CO2 and inorganic nutrients into plant material, is the ultimate source of the food protein necessary to man’s existence. Given certain assumptions, the overall maximal theoretical photosynthetic efficiency of agricultural plants can be calculated. Actual measured maximal growth rates of plants are equivalent to efficiency levels well below that theoretical maximum. In air, C4 plants can come closer to the theoretical value than C3 plants, perhaps because C4 plants avoid the occurrence of measurable photorespiration and oxygen inhibition of photosynthesis.
Alfalfa, a C3 legume, is an extremely productive protein source. Its protein yield per acre can surpass that of commonly grown C4 crops (corn, sorghum) and C3 seed crops (soybean, wheat, rice). Alfalfa leaf protein is of high nutritional quality and can apparently be used directly in the human diet, eliminating the protein loss involved in animal production.
Plant protein productivity can be raised as part of an increase in overall crop yield. The growth of plants in atmospheres with elevated CO2 levels can result in increased yields. In C3 plants this is due, at least in part, to the suppression of photorespiration and oxygen inhibition of photosynthesis. We have investigated the effect of CO2 concentration on alfalfa photosynthetic metabolism. Our results support the contention that alfalfa productivity can be increased by an environment of elevated CO2.
A second approach toward increased plant protein productivity is through regulation of carbon flow during photosynthesis so as to increase protein production relative to that of other plant constituents. In particular, we have investigated whether ammonia (the form in which plants first incorporate nitrogen) can act to regulate leaf carbon metabolism. Our results indicate that NH 4 + , in part through stimulation of pyruvate kinase, brings about increased production of amino acids at the expense of sucrose production in alfalfa. That effect may be of considerable importance in the regulation of green leaf protein synthesis.
KeywordsPyruvate Kinase Compensation Point Carbon Flow Bundle Sheath Cell Oxygen Inhibition
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- Alich, J. R., Jr. and Inman, R. E. (1973). ‘Effective utilization of solar energy to produce clean fuel.’ National Science Foundation RANN report under grant GI 38723.Google Scholar
- Bassham, J. A. (1973). Control of photosynthetic carbon metabolism. In, ‘Symposium of the Society for Experimental Biology 27, Rate Control of Biological Processes’. University Press, Cambridge.Google Scholar
- Bassham, J. A. (1978). The reductive pentose phosphate cycle and its regulation. In, Encyclopedia of Plant Physiology, New Series. Photosynthesis II. Regulation of Photosynthetic Carbon Metabolism and Related processes; M. Gibbs and E. Latzko (Editors). Springer Verlag, Berlin.Google Scholar
- Bassham, J. A. and Calvin, M. (1957). ‘The Path of Carbon in Photosynthesis.’ Prentice-Hall, Englewood Cliffs, N.J.Google Scholar
- Bickoff, E. M., Booth, A. N., de Fremery, D., Edwards, R. H., Knuckles, B. E., Miller, R. E., Saunders, R. M. and Kohler, G. O. (1975). Nutritional evaluation of alfalfa leaf protein concentrate. In, ‘Protein Nutritional Quality of Foods and Feeds’, M. Friedman (Editor). Marcel Dekker, New York.Google Scholar
- Bowman, J. C. (1973). Possibilities for changing by genetic means the biological efficiency of protein production by whole animals. In, ‘The Biological Efficiency of Protein Production,’ J. G. W. Jones (Editor). Cambridge University Press, London.Google Scholar
- Brown, A. W. A., Byerly, T. C., Gibbs, M. and San Pietro, A. (Editors). (1975). ‘Crop Productivity-Research Imperatives.’ Michigan Agricultural Experiment Station, East Lansing, MI.Google Scholar
- Burris, R. H. and Black, C. C. (Editors). (1976). ‘CO2 Metabolism and Plant Productivity.’ University Park Press, Baltimore, MD.Google Scholar
- Committee on Agricultural Production Efficiency. (1975). ‘Agricultural Production Efficiency.’ Board on Agriculture and Renewable Resources, Commission on Natural Resources, National Research Council. National Academy of Sciences, Washington, D. C.Google Scholar
- Cooper, J. P. (Editor). (1975). ‘Photosynthesis and Productivity in Different Environments.’ Cambridge University Press, Cambridge.Google Scholar
- Decker, J. P. (1957). Further evidence of increased carbon dioxide production accompanying photosynthesis. J. Sol. Energy Sci. Eng., 1, 30–33.Google Scholar
- De Fremery, D., Miller, R. E., Edwards, R. H., Knuckles, B. E., Bickoff, E. M. and Kohler, G. O. (1973). Centrifugal separation of white and green protein fractions from alfalfa juice following controlled heating. J. Agric. Food Chem., 21, 8C-889.Google Scholar
- Egle, K. and Fock, H. (1967). Light respiration - correlations between CO2 fixation, O2 pressure and glycolate concentration. In, ‘The Biochemistry of Chloroplasts’, T. W. Goodwin (Editor). Academic Press, New York.Google Scholar
- Ford, M. A. and Thorne, G. N. (1967). Effect of CO2 concentration on growth of sugar-beet, barley, kale and maize. Annals of Bot., 31. 629–644.Google Scholar
- Gifford, R. M. (1977). Growth pattern, carbon dioxide exchange and dry weight distribution in wheat growing under differing photosynthetic environments. Aust. J. Plant Physiol., 4, 99–110.Google Scholar
- Hardy, R. W. F. and Havelka, U. D. (1976). Photosynthate as a major factor limiting nitrogen fixation by field-grown legumes with emphasis on soybeans. In, ‘Symbiotic Nitrogen Fixation in Plants’, P. S. Nutman (Editor). Cambridge University Press, Cambridge.Google Scholar
- Hess, J. L. and Tolbert, N. E. (1966). Glycolate, glycine, serine, and glycerate formation during photosynthesis by tobacco leaves. J. Biol. Chem., 241, 5705–5711.Google Scholar
- Hofstra, G. and Hesketh, J. D. (1975). The effects of temperature and CO2 enrichment on photosynthesis in Soybean. In, Marcelle, R. (1975).Google Scholar
- Loewenberg, J. R. (1970). Protein synthesis in Xanthium leaf development. Plant and Cell Physiol., 11, 361–365.Google Scholar
- Loomis, R. S. and Gerakis, P. A. (1975). Productivity of agricultural ecosystems. In, Cooper, J. P. (Editor). (1975).Google Scholar
- Ludlow, M. M. and Jarvis, P. G. (1971). Methods for measuring photorespiration in leaves. In, ‘Plant Photosynthetic Production Manual of Methods,’ Z. Sestak, J. Catsky, and P. G. Jarvis (Editors). Dr. W. Junk, The Hague.Google Scholar
- Marcelle, R. (Editor). (1975). ‘Environmental and Biological Control of Photosynthesis’. Dr. W. Junk, The Hague.Google Scholar
- Nakayama, H., Fujii, M. and Miura, K. (1976). Partial purification and some regulatory properties of pyruvate kinase from germinating castor bean endosperm. Plant and Cell Physiol., 17, 653–660.Google Scholar
- Ogren, W. L. (1975). Control of photorespiration in soybean and maize. In, Marcelle, R. (1975).Google Scholar
- Osmond, C. B. and Bjorkman, O. (1972). Simultaneous measurements of oxygen effects on net photosynthesis and glycolate metabolism in C3 and C4 species of Atriplex. Carnegie Inst. Washington Yearbook, 71, 141–148.Google Scholar
- Platt, S. G., Erwin, W. and DeGroot, C. W. (1978). Simple push-pull glass valves. J. Chem. Ed., in press.Google Scholar
- Plaut, Z., Platt, S. G. and Bassham, J. A. (1976). Nitrate and ammonium regulation of carbon metabolism in photosynthesizing alfalfa leaf discs. Plant Physiol., 57, S-58.Google Scholar
- Seubert, W. and Schoner, W. (1971). The regulation of pyruvate kinase In, ‘Current Topics in Cellular Regulation, Volume 3,’ B. L. Horecker and E. A. Stadtman (Editors). Academic Press, New York.Google Scholar
- Tolbert, N. E. (1971a). Leaf peroxisomes and photosynthesis. In, ‘Photosynthesis and hotorespiration’, M. D. Hatch, C. B. Osmond and R. O. Slayter, (Editors). Wiley-Interscience, New York.Google Scholar
- Tolbert, N. E. (1973a). Compartmentation and control in micro-bodies. In: ‘Symposia of the Society for Experimental Biology 27, Rate Control of Biological Processes’. University Press, Cambridge.Google Scholar
- Tolbert, N. E. (1973b). Glycolate biosynthesis. In: ‘Current Topics in Cellular Regulation, Volume 7, B. L. Horecker and E. A. Stadtman (Editors). Academic Press, New York.Google Scholar
- Zelitch, I. (1965). The relation of glycolic acid synthesis to the primary photosynthetic carboxylation reaction in leaves. J. Biol. Chem., 240, 1869–1876.Google Scholar
- Zelitch, I. (1971). Photosynthesis, Photorespiration, and Plant Productivity. Academic Press, New York.Google Scholar
- Zelitch, I. (1975b). Environmental and biological control of photosynthesis: General assessment. In, Marcelle, R. (1975).Google Scholar