Fig. 1.

LEF dependencies of antenna regulation and light-driven proton flux across the thylakoid membrane. Chlorophyll a fluorescence yield and ECS analyses were used to obtain estimates of energy-dependent exciton quenching (q_E)(A) and steady-state proton flux into the lumen (ν_H+) (B), respectively, from 26 to 216 μmol photons m^-2s^-1 on leaves from A. thaliana Wt under ambient (372 ppm CO₂/21% O₂) (○) and low CO₂ (LC; 50 ppm CO₂/21% O₂) (▵) air, as well as pgr5 under ambient air (▪) and plotted as a function of estimated LEF (18). Linear regressions of LEF versus ν_H+ are shown in B, the regression slopes of which are 2.035 (solid line), 2.038 (dotted line), and 1.774 (dashed line) for Wt ambient air, Wt/LC air, and pgr5 ambient air, respectively. Slopes for Wt/atmospheric and pgr5/atmospheric were judged by analysis of covariance to be statistically different (P < 0.05). Error bars represent SE for n = 3–6.