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The role of transient starch in acclimation to elevated atmospheric CO 2
Author(s) -
Ludewig Frank,
Sonnewald Uwe,
Kauder Friedrich,
Heineke Dieter,
Geiger Michael,
Stitt Mark,
Müller-Röber Bernd T,
Gillissen Bernd,
Kühn Christina,
Frommer Wolf B
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00580-8
Subject(s) - photosynthesis , rubisco , starch , carbon dioxide , sucrose , chemistry , sugar , acclimatization , biochemistry , botany , food science , biology , organic chemistry
Although increased concentrations of CO 2 stimulate photosynthesis, this stimulation is often lost during prolonged exposure to elevated carbon dioxide, leading to an attenuation of the potential gain in yield. Under these conditions, a wide variety of species accumulates non‐structural carbohydrates in leaves. It has been proposed that starch accumulation directly inhibits photosynthesis, that the rate of sucrose and starch synthesis limits photosynthesis, or that accumulation of sugars triggers changes in gene expression resulting in lower activities of Rubisco and inhibition of photosynthesis. To distinguish these explanations, transgenic plants unable to accumulate transient starch due to leaf mesophyll‐specific antisense expression of AGP B were grown at ambient and elevated carbon dioxide. There was a positive correlation between the capacity for starch synthesis and the rate of photosynthesis at elevated CO 2 concentrations, showing that the capability to synthesize leaf starch is essential for photosynthesis in elevated carbon dioxide. The results show that in elevated carbon dioxide, photosynthesis is restricted by the rate of end product synthesis. Accumulation of starch is not responsible for inhibition of photosynthesis. Although transgenic plants contained increased levels of hexoses, transcripts of photosynthetic genes were not downregulated and Rubisco activity was not decreased arguing against a role of sugar sensing in acclimation to high CO 2 .