Two mechanisms account for far-red acclimation of light-harvesting complexes in cyanobacteria.

FR induced bulky allophycocyanin subunits covalently bind bilins to 1 or 2 cysteines.

Co-generation of α- and β-subunits, ApcA2 and ApcB2, results in 90 nm red-shift.

With the β-18 subunit, ApcF2, red-shift is based on non-covalent chromophore binding.

Red-shifts of the phycobilisome complement induction of red-shifted chlorophylls.