Chlamydomonas reinhardtii Exhibits De Facto Constitutive NPQ Capacity in Physiologically Relevant Conditions  . Issue 1 (25th October 2019)

• Record Type: Journal Article
• Authors: Nawrocki, Wojciech J.; Liu, Xin; Croce, Roberta
• Is Part Of: Plant physiology. Volume 182:Issue 1(2020)
• Page Start: 472
• Page End: 479
• Publication Date: 2019-10-25
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1104/pp.19.00658
• Languages: English
• ISSNs: 0032-0889

Abstract

Abstract : Under simulated high light, diel growth conditions, the photosynthetic apparatus of Chlamydomonas reinhardtii exhibits an almost constitutive photoprotection capacity through non-photochemical quenching. Abstract: The photosynthetic apparatus must be able to withstand light conditions that exceed its capacity for carbon fixation. Photosynthetic organisms developed nonphotochemical quenching (NPQ), a process that dissipates excess absorbed light energy as heat and limits the production of reactive oxygen species and cellular damage. In the green alga Chlamydomonas reinhardtii, the LHCSR pigment-binding proteins are essential for NPQ. These complexes are not constitutively present in the thylakoid membranes; however, in laboratory conditions their expression depends on prior high light exposure of cells. To investigate the role of NPQ, we measured cells grown under a day-night cycle with a high light peak at mid-day. LHCSRs are present and NPQ is active consistently throughout the day, likely due to their slow degradation in vivo. This suggests that in physiologically relevant conditions, Chlamydomonas cells are prepared to immediately activate photoprotection, as is the case in vascular plants. We further reveal that state transitions are fully functional under these conditions and that PsbS is highly expressed throughout the day, suggesting it might have a more impactful role than previously thought.