Investigation of the quenching efficiency of diatoxanthin in cells of Phaeodactylum tricornutum (Bacillariophyceae) with different pool sizes of xanthophyll cycle pigments

Abstract

Abstract In the present study, the content of diadinoxanthin (Dd) + diatoxanthin (Dt) in the diatom Phaeodactylum tricornutum was manipulated by low-light (LL) and high-light (HL) growth conditions. Cells grown in HL almost doubled the pool size of Dd cycle pigments compared to cells from a LL culture. HL-grown cultures exhibited a stronger de-epoxidation and higher amounts of Dt during actinic HL illumination. However, the correlation between Dt and the corresponding nonphotochemical quenching (NPQ) revealed that the quenching efficiency of Dt was drastically decreased in these HL-grown cells compared to cells from the LL cultivation. The correlation between the de-epoxidation state of the Dd cycle and NPQ implied that in HL-grown cells a part of the Dt molecules had lost their ability to contribute to the NPQ. A precise quantification of the amount of free Dd + Dt by anion exchange chromatography and high-performance liquid chromatography showed that only 10% of the additionally synthesized Dd cycle pig...