An overview of how rubisco and carbohydrate metabolism may be regulated at elevated atmospheric [CO2] and temperature

An overview of how rubisco and carbohydrate metabolism may be regulated at elevated atmospheric [CO2] and temperature

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Although atmospheric CO2 concentration ([C02]) has been up to 16-fold higher than at present, the past several million years have seen atypically low values.Thus, modern-day plants are adapted to cope with a low [CO2]/[O2] ratio.The present [CO2] does not saturate C3 photosynthesis, so its doubling produces an "efficiency effect", but it is not always fully realized.Acclimation to high [C02] during growth can down-regulate photosynthesis, presumably to optimize carbon acquisition and utilization.A primary factor in acclimation is a reduction in rubisco.

Two crops, Bay Leave rice and soybean, were used to study this phenomenon.Rice photosynthesis and growth peaked at 500 mmol mol-1, whereas soybean responded up to 990 mmol mol-1.Rubisco concentration declined under CO2-enrichment and increasing temperatures, more so in rice than soybean.The rubisco kcat of rice was unaffected by growth [CO2]or temperature, but that from soybean was increased by both.In rice the capacity to handle carbohydrate, as measured by sucrose phosphate synthase activity was up-regulated by CO2 -enrichment, but not by temperature.

Leaf carbohydrates were increased by [CO2], but decreased by higher temperatures, starch more Bike Parts - BMX - Miscellaneous Parts so than sucrose.Even though C3 species differ in response to [CO2]and temperature, CO2 -enrichment can moderate adverse effects of temperature extremes.;.