Figure 4.

A to C, CO₂ response of CO₂ assimilation rate (A) measured at 25°C and 40°C and 1,500 μmol photons m⁻² s⁻¹ in wild-type (WT) plants (A), plants with intermediate Rubisco activase contents (B), and plants with low Rubisco activase contents (C) grown at 30°C/25°C. The explanation of plant classification is given in Table I. A at 25°C is shown as black circles, whereas A at 40°C is shown as white circles. Rubisco-limited A (A_c; solid lines) was estimated from Equation 1, whereas RuBP regeneration-limited A (A_r; dotted lines) was estimated from Equation 2. D to F, Electron transport rate from chlorophyll fluorescence (J_f) as a function of chloroplast CO₂ concentration (C_c) at 25°C and 40°C in wild-type plants (D), plants with intermediate Rubisco activase contents (E), and plants with low Rubisco activase contents (F) grown at 20°C/15°C. J_f at 25°C is shown as black circles, whereas J_f at 40°C is shown as white circles. Arrows show measurements made at 380 μL L⁻¹ CO₂ concentration. Data represent means ± se; n = 4.