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Acclimation of Arabidopsis thaliana to long-term CO₂ enrichment and nitrogen supply is basically a matter of growth rate adjustment

Tocquin, Pierre, Ormenese, Sandra, Pieltain, Alexandra, Detry, Nathalie, Bernier, Georges, Périlleux, Claire
Physiologia plantarum 2006 v.128 no.4 pp. 677-688
Arabidopsis thaliana, acclimation, biomass production, carbohydrates, hydroponics, leaf area, leaves, messenger RNA, nitrogen, photosynthesis, proteins, ribulose-bisphosphate carboxylase, roots, shoots, stomatal conductance, vegetative growth
The long-term response of Arabidopsis thaliana to increasing CO₂ was evaluated in plants grown in 800 μl l⁻¹ CO₂ from sowing and maintained, in hydroponics, on three nitrogen supplies: "low,""medium" and "high." The global response to high CO₂ and N-supply was evaluated by measuring growth parameters in parallel with photosynthetic activity, leaf carbohydrates, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) messenger RNA and protein, stomatal conductance (gs) and density. CO₂ enrichment was found to stimulate biomass production, whatever the N-supply. This stimulation was transient on low N-supply and persisted throughout the whole vegetative growth only in high N-supply. Acclimation on low N-high CO₂ was not associated with carbohydrate accumulation or with a strong reduction in Rubisco amount or activity. At high N-supply, growth stimulation by high CO₂ was mainly because of the acceleration of leaf production and expansion while other parameters such as specific leaf area, root/shoot ratio and gs appeared to be correlated with total leaf area. Our results thus suggest that, in strictly controlled and stable growing conditions, acclimation of A. thaliana to long-term CO₂ enrichment is mostly controlled by growth rate adjustment.