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Photorespiratory compensation: a driver for biological diversity
Author(s) -
Sage R. F.
Publication year - 2013
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1111/plb.12024
Subject(s) - photorespiration , biology , rubisco , photosynthesis , chloroplast , botany , limiting , terrestrial plant , transpiration , biophysics , biochemistry , mechanical engineering , engineering , gene
This paper reviews how terrestrial plants reduce photorespiration and thus compensate for its inhibitory effects. As shown in the equation ϕ = (1/ S c/o ) O / C , where ϕ is the ratio of oxygenation to carboxylation, S c/o is the relative specificity of Rubisco, O is stromal O 2 level and C is the stromal CO 2 concentration, plants can reduce photorespiration by increasing S c/o or C , or by reducing O . By far the most effective means of reducing ϕ is by concentrating CO 2 , as occurs in C 4 and CAM plants, and to a lesser extent in plants using a glycine shuttle to concentrate CO 2 into the bundle sheath. Trapping and refixation of photorespired CO 2 by a sheath of chloroplasts around the mesophyll cell periphery in C 3 plants also enhances C , particularly at low atmospheric CO 2 . O 2 removal is not practical because high energy and protein investment is needed to have more than a negligible effect. S c/o enhancement provides for modest reductions in ϕ, but at the potential cost of limiting the k cat of Rubisco. An effective means of decreasing ϕ and enhancing carbon gain is to lower leaf temperature by reducing absorbance of solar radiation, or where water is abundant, opening stomata. By using a combination of mechanisms, C 3 plants can achieve substantial (>30%) reductions in ϕ. This may have allowed many C 3 species to withstand severe competition from C 4 plants in low CO 2 atmospheres of recent geological time, thereby preserving some of the Earth's floristic diversity that accumulated over millions of years.