Dissection of photosynthetic short- and long-term acclimation to fluctuating light reveals specific functions of the chloroplast thioredoxin network

Dziubek, Dejan ; Poeker, Louis ; Jäger, Luca; Lehmann, Martin ; Leister, Dario ; Armbruster, Ute ; Geigenberger, Peter und Lawson, Tracy (2025): Dissection of photosynthetic short- and long-term acclimation to fluctuating light reveals specific functions of the chloroplast thioredoxin network. In: Journal of Experimental Botany, Bd. 76, Nr. 13: S. 3851-3871

Abstract

Thioredoxins (TRXs) play an important role in controlling photosynthetic acclimation to fluctuating light (FL), but the underlying mechanisms remain unclear. Here, we used Arabidopsis mutants lacking NADPH-dependent TRX-reductase C (NTRC) or parts of the light-dependent TRX system to investigate the specific functions of this network in FL. In the wild type, photosynthetic acclimation required 3 d to develop and stabilized after 5 d of growth in FL. In the ntrc mutant, these acclimation responses were strongly attenuated, leading to decreased PSII acceptor availability, increased non-photochemical quenching (NPQ), and impaired PSII quantum efficiency. Moreover, PSI performance decreased, while acceptor-side limitation of PSI increased. This was particularly due to a strong decline in the reduction states of 2-Cys-peroxiredoxins and fructose-1,6-bisphosphatase, resulting in decreased CO2-fixation rates and delayed relaxation of NPQ in the low-light phases of FL. Since this was not reflected by changes in de-epoxidation of violaxanthin, state transition, or chlorophyll a level, the ntrc mutants showed an apparent lack of photoprotective responses that might explain their increased vulnerability under prolonged growth in FL. Our results show that NADPH-dependent NTRC balances chloroplast redox-systems to optimize the activity of the Calvin–Benson cycle during prolonged light variability in order to optimize PSI, PSII, and water-use efficiency, while having no direct effect on photoprotective mechanisms.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Biologie
• Themengebiete: 500 Naturwissenschaften und Mathematik > 570 Biowissenschaften; Biologie
• ISSN: 0022-0957
• Sprache: Englisch