What was done
The authors grew Arabidopsis thaliana in environmental chambers receiving atmospheric CO2 concentrations of 360 and 1,000 ppm for 40 days to determine how elevated CO2 induces acclimation in this species.

What was learned
Plants grown in elevated CO2 exhibited significant enhancements in tissue concentrations of total nonstructural carbohydrates.  Glucose and fructose concentrations, for example, were increased in CO2-enriched plants by more than 2-fold, while starch was enhanced by approximately 3.5-fold.  Such increases in these photosynthetically-derived sugars likely aided in the induction of acclimation in the CO2-enriched plants.  Indeed, plants grown at 1,000 ppm CO2 exhibited rubisco protein contents that were about 34% less than those displayed by ambiently-grown plants.  This common acclamatory response likely resulted from observed CO2-induced reductions in the amounts of mRNA transcripts for rbcL and rbcS by nearly 40 and 60%, respectively.

What it means
Even though Arabidopsis thaliana has little biological importance in the natural world, it is often used in laboratory experiments to better understand biochemical mechanisms that control plant physiological processes.  The data collected in this study, for example, suggest that the accumulation of total nonstructural carbohydrates in CO2-enriched plants signaled the onset of photosynthetic acclimation to elevated CO2.  Mechanistically, this process was likely controlled at the level of transcription, as indicated by CO2-induced reductions in mRNA transcripts for the large and small subunits of rubisco.