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Over-expressing the C3 photosynthesis cycle enzyme Sedoheptulose-1-7 Bisphosphatase improves photosynthetic carbon gain and yield under fully open air CO2fumigation (FACE)

Rosenthal, David M and Locke, Anna M and Khozaei, Mahdi and Raines, Christine A and Long, Stephen P and Ort, Donald R (2011) 'Over-expressing the C3 photosynthesis cycle enzyme Sedoheptulose-1-7 Bisphosphatase improves photosynthetic carbon gain and yield under fully open air CO2fumigation (FACE).' BMC Plant Biology, 11 (1). 123-. ISSN 1471-2229

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Abstract

<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background</jats:title> <jats:p>Biochemical models predict that photosynthesis in C<jats:sub>3</jats:sub> plants is most frequently limited by the slower of two processes, the maximum capacity of the enzyme Rubisco to carboxylate RuBP (V<jats:sub>c,max</jats:sub>), or the regeneration of RuBP via electron transport (J). At current atmospheric [CO<jats:sub>2</jats:sub>] levels Rubisco is not saturated; consequently, elevating [CO<jats:sub>2</jats:sub>] increases the velocity of carboxylation and inhibits the competing oxygenation reaction which is also catalyzed by Rubisco. In the future, leaf photosynthesis (<jats:italic>A</jats:italic>) should be increasingly limited by RuBP regeneration, as [CO<jats:sub>2</jats:sub>] is predicted to exceed 550 ppm by 2050. The C<jats:sub>3</jats:sub> cycle enzyme sedoheptulose-1,7 bisphosphatase (SBPase, EC 3.1.3.17) has been shown to exert strong metabolic control over RuBP regeneration at light saturation.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>We tested the hypothesis that tobacco transformed to overexpressing SBPase will exhibit greater stimulation of <jats:italic>A</jats:italic> than wild type (WT) tobacco when grown under field conditions at elevated [CO<jats:sub>2</jats:sub>] (585 ppm) under fully open air fumigation. Growth under elevated [CO<jats:sub>2</jats:sub>] stimulated instantaneous <jats:italic>A</jats:italic> and the diurnal photosynthetic integral (<jats:italic>A</jats:italic>') more in transformants than WT. There was evidence of photosynthetic acclimation to elevated [CO<jats:sub>2</jats:sub>] via downregulation of V<jats:sub>c,max</jats:sub> in both WT and transformants. Nevertheless, greater carbon assimilation and electron transport rates (J and J<jats:sub>max</jats:sub>) for transformants led to greater yield increases than WT at elevated [CO<jats:sub>2</jats:sub>] compared to ambient grown plants.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusion</jats:title> <jats:p>These results provide proof of concept that increasing content and activity of a single photosynthesis enzyme can enhance carbon assimilation and yield of C<jats:sub>3</jats:sub> crops grown at [CO<jats:sub>2</jats:sub>] expected by the middle of the 21st century.</jats:p> </jats:sec>

Item Type: Article
Uncontrolled Keywords: climate change; photosynthetic carbon reduction cycle; C3 plants; RuBP regeneration; electron transport; improving photosynthesis
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health
Faculty of Science and Health > Life Sciences, School of
SWORD Depositor: Elements
Depositing User: Elements
Date Deposited: 13 Mar 2013 20:58
Last Modified: 15 Jan 2022 00:18
URI: http://repository.essex.ac.uk/id/eprint/5839

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