Figure 3.

Analyses of the activities of the various NDH complexes. A, Monitoring of NDH activity by chlorophyll fluorescence analysis. Four-week-old plants were illuminated for 5 min with AL (50 μmol photons m⁻² s⁻¹). After illumination, NDH activity was monitored as the subsequent transient increase in chlorophyll fluorescence. The fluorescence levels were normalized by the F_m levels. The definition of leaf age is the same as in a previous report (Peng et al., 2009). a.u., Arbitrary units. B, Fd-dependent PQ reduction assay. Increases in chlorophyll fluorescence by the addition of NADPH (0.25 mm) and Fd (5 μm) under weak illumination (1.0 μmol photons m⁻² s⁻¹) were monitored in osmotically ruptured chloroplasts (20 μg chlorophyll mL⁻¹) of wild-type (WT), lhca5, lhca6, crr2-2, and lhca5 lhca6 mature leaves. Ruptured chloroplasts were incubated with 10 μm antimycin A before measurement. The maximum fluorescence level in the wild type corresponded to approximately 40% of the F_m level. This is a representative result of three experiments using thylakoid membranes isolated independently.