Figure 1.

V cycle and NPQ in the npq1 mutant of A. thaliana. (A) Conversion of V to A and Z, as monitored by the (A + Z)/(A + Z + V) ratio, in leaves of the wild type and npq1 mutant suddenly exposed to a strong, white light of PFD of 1,500 μmol of photons·m⁻²·s⁻¹. (B) Quenching of F_m induced by the strong, white light and subsequent relaxation of the fluorescence quenching in the dark. The F_o and F_m fluorescence levels at time 0 were identical in the wild type and the mutant.