Figure 2.

Kinetics of CO₂-dependent accumulation and removal of SA (A) and analysis of SA and SA-related gene expression in Arabidopsis Col-0 (B) at two different concentrations of high CO₂ (hCO₂). In A, plants were grown in 16-h days at an irradiance of 200 µmol m⁻² s⁻¹ for 18 d, either in air (left) or at high CO₂ (1,000 µL L⁻¹; right). At time 0, plants were transferred to the other condition, either high CO₂ (left) or air (right). Mean leaf SA contents in plants after 21 d continuous growth in air and high CO₂ were 0.32 ± 0.06 µg g⁻¹ fresh weight (FW; n = three independent experiments, 10 biological replicates) and 5.86 ± 0.14 µg g⁻¹ fresh weight (n = seven independent experiments, 24 biological replicates), respectively. In B, plants were grown from seed for 3 weeks either in air (black bars) or high CO₂ (white bars). At left, high CO₂ was 1,000 µL L⁻¹; at right, high CO₂ was 3,000 µL L⁻¹. Data are means ± se of four (SA contents) or three (transcripts) biological replicates. Numbers above the bars indicate fold change for high CO₂-air. Significant differences between the conditions at P < 0.05 are indicated by asterisks.