Journal Article

Rubisco, Rubisco activase, and global climate change

Rowan F. Sage, Danielle A. Way and David S. Kubien

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 59, issue 7, pages 1581-1595
Published in print May 2008 | ISSN: 0022-0957
Published online April 2008 | e-ISSN: 1460-2431 | DOI: http://dx.doi.org/10.1093/jxb/ern053
Rubisco, Rubisco activase, and global climate change

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Global warming and the rise in atmospheric CO2 will increase the operating temperature of leaves in coming decades, often well above the thermal optimum for photosynthesis. Presently, there is controversy over the limiting processes controlling photosynthesis at elevated temperature. Leading models propose that the reduction in photosynthesis at elevated temperature is a function of either declining capacity of electron transport to regenerate RuBP, or reductions in the capacity of Rubisco activase to maintain Rubisco in an active configuration. Identifying which of these processes is the principal limitation at elevated temperature is complicated because each may be regulated in response to a limitation in the other. Biochemical and gas exchange assessments can disentangle these photosynthetic limitations; however, comprehensive assessments are often difficult and, for many species, virtually impossible. It is proposed that measurement of the initial slope of the CO2 response of photosynthesis (the A/Ci response) can be a useful means to screen for Rubisco activase limitations. This is because a reduction in the Rubisco activation state should be most apparent at low CO2 when Rubisco capacity is generally limiting. In sweet potato, spinach, and tobacco, the initial slope of the A/Ci response shows no evidence of activase limitations at high temperature, as the slope can be accurately modelled using the kinetic parameters of fully activated Rubisco. In black spruce (Picea mariana), a reduction in the initial slope above 30 °C cannot be explained by the known kinetics of fully activated Rubisco, indicating that activase may be limiting at high temperatures. Because black spruce is the dominant species in the boreal forest of North America, Rubisco activase may be an unusually important factor determining the response of the boreal biome to climate change.

Keywords: Black spruce; climate change; C3 photosynthesis; Picea mariana; Rubisco; Rubisco activase; temperature

Journal Article.  10029 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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