Figure 5.

Requirement for RBOH1 in systemic light signaling from the shoot apex to distal leaves for the regulation of CO₂ assimilation rates and CEF during the induction phase of photosynthesis. A to C, Time course of increases in net photosynthesis rate during photosynthetic induction and T50 or T90 in the fourth leaves. Net photosynthetic rates are expressed as percentages of the maximum net photosynthesis rate. D and E, Typical traces of chlorophyll a fluorescence quenching after 4 min of actinic illumination (250 μmol m⁻² s⁻¹) in grafted plants with rboh1 mutant rootstocks. a.u., Arbitrary unit. F, Relative chlorophyll (Chl) fluorescence expressed as the rake ratio of the induction curve. Irradiance to the shoot apex (top lighting) was performed with WL (L) at 300 μmol m⁻² s⁻¹ for 30 min. Plants without preillumination (dark [D]) were used as controls. During the illumination treatments, the other parts of the plant were kept in darkness. Values are means of four plants ± sd. Different letters indicate significant differences at P < 0.05 according to Tukey’s test.