Effect of elevated atmospheric CO2 level on seed lipids and on diurnal leaf lipid composition in Arabidopsis thaliana

While the effects of elevated atmospheric CO2 level on starch and sugar metabolism have been extensively studied in different plants, the effect on plant lipid metabolism concerns only a few studies and none of these are on the model plant Arabidopsis thaliana. This study of the lipid composition in seeds and leaves of A. thaliana is therefore of interest when trying to predict how the future environment will change the conditions for plant lipid metabolism and oil crop productivity. Total leaf lipid concentration on a dry weight basis, starch excluded, was 15% lower at elevated CO2 compared to ambient. The fatty acid profile of total leaf lipids showed large diurnal variations, oleic acid increased 2-fold during the first 9 h of illumination and decreased correspondingly during night as expected of the light dependence of de novo fatty acid synthesis. Elevated CO2 did not induce any large differences in this diurnal pattern. However, elevated CO2 induced a 24% lower ratio trans Δ3hexadecenoic acid to palmitic acid in phosphatidyl glycerol. With good nutrient supply, growth at elevated CO2 did not affect either single seed weight, total seed mass, oil yield, or fatty acid profile of seeds significantly. This study shows that elevated atmospheric CO2 cause changes in leaf lipid metabolism in the plant A. thaliana, however, no large differences in seed lipids can be observed.