apcG deletion and phosphorylation impact PSII and PSI energy balance. Synechocystis cultures were grown to compare their fluorescence under low temperature (77 K). Each curve on the spectra represents the mean from 3 biological replicates. All cultures were preincubated at room temperature in darkness for 15 min before measurements. A) Fluorescence emission spectra of chlorophyll from Synechocystis with an excitation of 430 nm. The first peak at 680 nm corresponds to the fluorescence from PSII, while the one around 720 nm to PSI. Values correspond to mean of 3 biological replicates while normalizing the data to 800 nm. B) Fluorescence emission spectra of Synechocystis strains by exciting PBS at 590 nm. The fluorescence peak at 650 to 660 nm corresponds to PBS, 680 nm to PSII, and 720 nm to PSI. Values correspond to the means of 3 biological replicates while normalizing the data to the peak of PBS at 660 nm.