Presence of flexible non-photochemical quenching in cryptophytes (Rhodomonas Salina)

Abstract

Photosynthesis uses light as a source of energy but its excess can result in damage of photosynthetic apparatus. The protective mechanism of non-photochemical quenching (NPQ) can safely dissipate excess of light to heat. Presence and mechanism of NPQ regulation differs between photothrophs. Here we show presence of non-photochemical quenching in cryptophyte alga (Rhodomonas salina), that represents unique clade of chromalveolates. Cryptophytes are exceptional among photosynthetic chromalveolates (that include also diatoms and other Chl c containing algae) because beside membrane-bound chlorophyll a/c proteins they also contain lumenal phycobiliproteins. We have shown that NPQ in R. salina is stimulated by light absorbed by chlorophyll (orange light — 620 nm) and phycoerythrin (green light — 520 nm) to the same extent with the same maximal value around 1.6. Kinetic pattern of NPQ stimulation in high light and its recovery in dark resemble flexible energetic quenching, qE. It indicates different regulation of NPQ in cryptophytes in comparison to the same process known in diatoms because there recovery from quenching state is usually less flexible.