Effect of AtLFNR1 deficiency on chlorophyll a fluorescence rise kinetics OJIP of Arabidopsis

Leaf-type ferredoxin-NADP(H) oxidoreductase, encoded by AtLFNR1 gene in Arabidopsis, extensively exists in chloroplast stroma and thylakoids and is responsible for the reduction of NADP(+) to NADPH in PSI. To investigate the relationship between the characteristics of chlorophyll a fluorescence transients OJIP and the function of AtLFNR1 protein, the fluorescence rise kinetics OJIP curves of AtLFNR1 mutant leaves were determined. It is observed that AtLFNR1 mutant has a lower level of variable fluorescence intensity relative to wild type, especially the J-step and the IP-phase. The JIP-test analysis suggests that the loss of AtLFNR1 function decreases clearly the oxidation rate of plastocyanin as well as PSI reaction center, damages slightly PSII antenna size and pigment assemblies, but stimulates distinctly the photosynthetic activity of PSII. Such multiple effects contribute to the change of shape characteristics of the OJIP transient curve in AtLFNR1 mutant.