Fig 2. Light-intensity dependence of the photochemical and non-photochemical quenching in wild type Synechocystis, its mutant derivatives M55 and ΔOx, and the green alga Chlorella.
Light-intensity dependent levels of photochemical (♦, qP) and non-photochemical quenching (●, qN). Values were derived from the data described and depicted in Fig 1. QP was calculated as (FM'-F)/(FM'-F0') and qN as 1-((FM'-F0')/(FM-F0)) with: F0, lowest level of fluorescence after dark adaptation; F0' lowest level of fluorescence after light incubation; F, steady-state fluorescence in the presence of actinic light; FM, fluorescence upon a strong light pulse on dark adapted cells or after addition of DCMU (ΔOx mutant only). FM', fluorescence upon a saturation pulse in the presence of actinic light. Data are the average from duplicate measurements, standard deviation was between 1 and 5%.