The use of far-red light (FRL) is observed in some cyanobacteria, as well as in some marine and freshwater algae. While algae mobilize FRL absorbing antenna, which contains common chlorophyll a (Chl a), cyanobacteria produce red-shifted Chl d and/or Chl f. These pigments are synthesized either irrespective of ambient light or synthesized during FRL photoacclimation (FaRLiP), or adaptive remodeling of photosynthetic apparatus induced by relative enrichment with FRL quanta. The presence of red-shifted chlorophylls as well as their functions and topography are registered with various methods based on fluorescence measurement, such as: (1) steady-state fluorescence detection in live cells, cell fractions, and photosynthetic apparatus constituents; (2) time-resolved fluorescence spectroscopy, which traces energy transfer between individual pigments; (3) confocal laser scanning microscopy (CLSM), which helps to localize photosynthetic pigments in situ. This chapter describes photosynthetic apparatus in cyanobacteria and their photoacclimation phenomena. Over past decades, FRL photoacclimation has been studied in a small number of cyanobacteria. Novel Chl f-producing strains Chlorogloeopsis sp. CALU 759 and Synechocystis sp. CALU 1173 would represent promising model objects. Importantly, although they belong to alternative morphotypes and distant phylogenetic lineages, fluorescence pattern of their FRL-grown cells similarly falls within general FaRLiP response.
Part of the book: Fluorescence Methods for Investigation of Living Cells and Microorganisms