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Effects of CO/sub 2/ concentration on rubisco amount, activity, and photosynthesis in soybean leaves

Conference · · Plant Physiol., Suppl.; (United States)
OSTI ID:6031150
Soybeans were grown at CO/sub 2/ concentrations ranging from 160 to 990 ..mu..l L/sup -1/ in outdoor chambers receiving natural sunlight. Leaf soluble protein and total rubisco activity decreased with increasing growth CO/sub 2/, when expressed on a dry weight basis, but no decrease occurred on an area basis. On an area basis, leaf photosynthetic rates of plants grown at 330 and 660 ..mu..l CO/sub 2/ L/sup -1/, and measured over a range of intercellular CO/sub 2/ of 50 to 680 ..mu..l CO/sub 2/ L/sup -1/, were always greater in the high CO/sub 2/ grown plants. Rubisco content (percent of soluble protein) and total activity (soluble protein basis), remained unchanged over the range of growth CO/sub 2/. Since rubisco content and total activity per m/sup 2/ were independent of growth CO/sub 2/ concentration, the enhanced rate of photosynthesis of leaves grown at high CO/sub 2/ was apparently not due to an increase in rubisco amount or activity. Soybean grown at high CO/sub 2/ has an extra palisade cell layer per unit leaf area. Thus, the greater photosynthetic rates of high CO/sub 2/ grown leaves may result from an enhanced ability of CO/sub 2/ to gain access to rubisco via increased total mesophyll cell surface area.
Research Organization:
Univ. of Florida, Gainesville
DOE Contract Number:
AI01-81ER60001
OSTI ID:
6031150
Report Number(s):
CONF-8707108-
Conference Information:
Journal Name: Plant Physiol., Suppl.; (United States) Journal Volume: 83:4
Country of Publication:
United States
Language:
English