Fig. 4.

PSI activity and CO₂ assimilation. WT, 6, and 9 indicate control plants for WT, CpNifS-6, and CpNifS-9 respectively, and WT-E, 6-E, and 9-E indicate the respective ethanol-treated plants. (A) PSI activity. Shown is the extent of the ΔA₈₂₀ (absorbance change at 820 nm, indicative of the P700 activity of PSI) induced with a flash of saturating light, in relative units. (B) Rate of reduction of PSI by upstream electron donors. Values, in relative units, represent the initial rate of the absorbance change at 820 nm (ΔA₈₂₀/s) in darkness after complete photooxidation of P700, which results mainly from reduction of P700⁺ by upstream electron donors. (C) Leaf photosynthetic CO₂ uptake. (D) Leaf respiratory O₂ consumption. P < 0.05 for ethanol-treated 6-E and 9-E for A–C. All values are the average and standard error of five independent measurements.