Figure 3.

Rates of NADP⁺ photoreduction by thylakoids from wild-type and transgenic plants overexpressing FNR. NADP⁺ photoreduction activity by thylakoids isolated from 6-week-old wild-type (black circles) or transgenic plants accumulating 4.6-fold FNR over the wild-type levels (white circles) were measured as indicated in “Materials and Methods,” using either water (A) or ascorbate-TMPD (B) as electron donors. DCMU was added to a final concentration of 2.2 μm in the latter case to prevent electron transport from PSII. Reaction rates (in μmol NADPH mg⁻¹ chl min⁻¹) were 0.57 (wild type) and 0.67 (pFNR-3) in A and 0.74 (wild type) and 2.36 (pFNR-3) in B.