Xanthophyll cycle-related non-photochemical quenching protects Sargassum thunbergii from high light-induced photoinhibition

• DOI: 10.3389/fmars.2022.1067596
• Publication Date: 2022-12-22T11:55:52Z
• Authors: Guo-Ning Nan; Xiao-Qun Zhou; Xiu-Mei Zhang; Quan-Sheng Zhang; Zi-Min Hu; Rui-Ping Huang; Di Zhang
• Keywords: Photoinhibition; Violaxanthin; Photoprotection; Non-photochemical quenching

As a common macroalga living in the intertidal zone, Sargassum thunbergii (Sargassaceae, Phaeophyta) is often exposed to drastic changes solar photosynthetically active radiation during diurnal cycle; thus, potential photosynthetic adaptation processes deserve attention. In this work, we examined performance and xanthophyll cycle activity of alga response high light (1,200 μmol photons m –2 s –1 , average in-situ intensity at noon) by using chlorophyll fluorescence high-performance liquid chromatography (HPLC). On exposure light, rapid decrease effective quantum yield photosystem II (PSII) (Y(II)) occurred, indicating down-regulation PSII activity; corresponding increase non-photochemical quenching (NPQ) indicated existence energy-dissipating cycles. After turning off Y(II) gradually increased 0.7, accompanied NPQ. However, no complete recovery NPQ was observed, its value remained ≈4, even after an 80-min dark treatment. The size pigments pool quantified HPLC found be ≈16 mol −1 Chl × 100. cycle, characterized de-epoxidation state (DPS), could reach up ≈0.5. Such large accumulation zeaxanthin may allow S. induce values (≈10). These results were further complemented inhibitor (dithiothreitol, DTT) pre-illumination experiments showing that (1) both inhibited DTT, there always strong positive correlation between DPS; (2) previously formed antheraxanthin exhibited long retention time slow epoxidation; (3) contributed zeaxanthin. conclusion, our present study demonstrated cycle-induced can significantly protect from fluctuations zone.