Figure 7.

The Effect of Altered Polyprenol Levels on Photosynthetic Performance.

(A) PSII operating efficiency (Φ_PSII) and maximum quantum efficiency of PSII (F_v/F_m; inset) were derived from steady state chlorophyll a fluorescence measurements performed on dark-adapted rosette leaves from the wild type (Col-0), a knockout line (cpt7−/−), three independent RNAi lines (RNAi), and an overexpression line (CPT7-OE). Note the significant decline in Φ_PSII in polyprenol-deficient leaves, while F_v/F_m remains unaltered in all lines. Data are the means ± sd from at least 10 independent experiments, and asterisks indicate a significant difference (Student’s t test; P < 0.05) when comparing Φ_PSII values to those obtained from the wild type.

(B) Polyprenol deficiency results in a decline in photosynthetic electron transport. Thylakoid membranes from these plants were illuminated in the presence of the oxidized artificial electron acceptor 2,6-dichlorophenolindophenol (DCPIP_[OX]), and its rate of reduction was monitored spectrophotometrically over the indicated time period. The rate of DCPIP reduction by thylakoids from each plant line is the average value from five independent preparations.