Abstract
We investigated relationship between Φ2*PFD and Jg in photosynthesis of Synechocystis sp. PCC6803.
Both Φ2 and Jg were simultaneously estimated from both chl fluorescence yield and O2 evolution rate analyses.
Both Fm, and Fs decreased with the increase in intensity of white light (WL), but these did not decrease with red light (RL). These parameters decreased with lowering intensity of green light. The decreases in both Fm, and Fs were not induced by state transition, respiration, or the Water-Water-Cycle (WWC). We propose that both Fm, and Fs were regulated by Orange Carotenoid Protein (OCP) which controls energy transfer efficiency from PS2-antenna to the reaction-center of PS2.
Φ2*PFD/Jg (=K) increased at strong intensity of WL. But K did not change even at strong intensity of RL. These results indicated AEF did not work under the condition where electron-sink was limited. In addition,both V(O2) and Φ2 did not change in anoxia. These results showed that WWC activity as AEF was very low under WL, and the increase in K under WL was due to the decrease in efficiency of collecting light energy by OCP system. Our data suggests that Φ2 can be related to Jg under RL.
