Abstract
The Arabidopsis thaliana mutant, cfa1, was originally isolated as a mutant that showed altered chlorophyll fluorescence induction kinetics. Furthermore, cfa1 showed somewhat slower growth compared with WT plants especially under high light condition. When we used pulse amplified modulation (PAM) fluometry under weak light (40 μmol/m2/s) and 0% CO2 with different O2 concentrations, cfa1 showed lower photochemical quenching (qP) as well as lower non-photochemical quenching (NPQ) than WT only under 2-5% O2 conditions. The results indicate that the electron transport chain was more reduced and the thermal dissipation was suppressed in cfa1 compared with WT. Since cfa1 and WT did not show significant difference in photosynthetic parameters under 0% O2, we concluded that CFA1 functioned in enhancing the affinity to O2 in O2-dependent reaction such as photorespiration or water-water cycle.
