The FaRLiP response is observed in some species of cyanobacteria, allowing different chlorophylls to be expressed in response to high levels of far-red light.
The genes for this response are found within photosynthetic gene clusters (PGC). The expression of these genes is controlled by light-sensitive promoters, ensuring they are only transcribed when far-red light is present, such as in soils and some rocks.
Being able to change the wavelengths of light absorbed through photosynthesis increases the metabolic flexibility of the cyanobacteria, as well as increasing the range of niches they are able to live and grow in. For example, fewer bacteria are able to grow deep in soil, however if a cyanobacteria is able to absorb far-red light (which penetrates much deeper into the soil), it can reside in a less competitive environment.
To allow a bacterium to accommodate the f and d chlorophylls (both are far-red absorbing), the photosystems must be remodelled to accommodate them. Therefore, the PGC contains paralogues of photosystems I and II and the phycobilisome antenna.