Increased nonphotochemical quenching in the eifiso4g mutant as a function of light intensity. NPQ (A) and quantum yield (B) of PSII (φPSII) and photochemical quenching (C, qP) were measured in dark-adapted WT (filled diamonds), eif4e (filled triangles), eifiso4e (open triangles), eif4g (open squares), eif4g/eifiso4g1 (open diamonds), and eifiso4g1/2 (filled squares) plants grown at 250 PFD to a similar developmental stage and exposed to a range of light intensities. Four to five replicates were assayed for each line with the average and standard error reported.