PSI oligomerization was altered in fkb20-2. A) The concentration of chlorophyll a and b was measured with the LL-grown WT, fkb20-2, and fkb20-2C. The average values and Sd were calculated from biological triplicates. The ratio between chlorophyll a and b in each strain was indicated on the top. For the comparison of the values between WT and other strains, the asterisks denote statistical significance according to 2-tailed Student's t-test: *P < 0.05; **P < 0.01. B) The accumulation of PSII (D1, CP43, and CP47), PSI (PsaA, PsaD, and LhcA2), Cytb₆f (Cytb₆) and ATPase (AtpA) subunits was analyzed by immunoblotting. The relative protein amount was indicated below the blots based on the quantification of the foci by ImageJ. C) The accumulation of photosynthesis complexes in WT and fkb20-2 was analyzed by immunoblotting on the 2D following 1D BN-PAGE. The position of PSI supercomplexes with LHCI (PSI-super) and that of PSI intermediate complexes (PSI-inter) were indicated below. D) 77-K fluorescence emission spectra of WT, fkb20-2, and fkb20-2C grown under LL was measured after excitation at 436 nm. The signals were normalized to the PSII emission maximum at 685 nm.