Photosynthetic parameters of WT Arabidopsis leaves and leaves of the pdx1 mutant grown under control conditions (150-200 μmol m-2 s-1, 25°C). A) Quantum yield of PSII photochemistry (ΔF/Fm'), B) oxygen exchange and C) NPQ measured at different PFDs. Data are mean values of 3 or 4 measurements ± SD. D) Light-induced conversion of violaxanthin (V) into zeaxanthin (Z) and antheraxanthin (A), as calculated by the equation (A+Z)/(V+A+Z). Zeaxanthin synthesis was induced by white light of PFD 1000 μmol m-2 s-1. Each point corresponds to a different leaf (1 measurement per point).