Figure 5.
Spectroscopic analyses of WT, petc-2, and atpd-1 plants. a, Effective quantum yield of PSII (ϕII) in leaves of atpd-1, petc-2, and WT plants determined at different photon flux densities. Leaves were dark-adapted for 30 min before the measurements were made. Mean values of five independent experiments are shown. Bars indicate sds. b, Thylakoid membrane potential decay of WT and atpd-1 leaves. Maximum transthylakoid proton gradient was reached by exposing 4-week-old leaves of WT and atpd-1 plants to a saturating light pulse for 15 and 25 ms, respectively. The dark-induced thylakoid membrane potential decay was then monitored by recording the absorption at 520 nm. For the absorption measurements, short light pulses at 520 nm were used to prevent actinic effects. The results of one out of five measurements are shown. c, Steady-state levels of oxidized reaction center Chl in PSI (P700+) in WT and mutant plants (n = 3 each). The steady-state level of P700+ was measured from the change in P700 absorption at 820 nm (ΔA/ΔAMAX) after 5 min of illumination with actinic light. Mean values are shown, and bars indicate sds.