Faster photosynthetic induction in tobacco by expressing cyanobacterial flavodiiron proteins in chloroplasts
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Plants grown in the field experience sharp changes in irradiation due to shading effects caused by clouds, other leaves, etc. The excess of absorbed light energy is dissipated by a number of mechanisms including cyclic electron transport, photorespiration, and Mehler-type reactions. This protection is essential for survival but decreases photosynthetic efficiency. All phototrophs except angiosperms harbor flavodiiron proteins (Flvs) which relieve the excess of excitation energy on the photosynthetic electron transport chain by reducing oxygen directly to water. Introduction of cyanobacterial Flv1/Flv3 in tobacco chloroplasts resulted in transgenic plants that showed similar photosynthetic performance under steady-state illumination, but displayed faster recovery of various photosynthetic parameters, including electron transport and non-photochemical quenching during dark–light transitions. They also kept the electron transport chain in a more oxidized state and enhanced the proton motive force of dark-adapted leaves. The results indicate that, by acting as electron sinks during light transitions, Flvs contribute to increase photosynthesis protection and efficiency under changing environmental conditions as those found by plants in the field.
KeywordsPhotosynthesis Alternative electron transport Flavodiiron proteins Non-photochemical quenching Dark–light transitions Photosynthetic efficiency
We thank Álvaro Quijano (Universidad Nacional de Rosario, FCAgR, Argentina) for providing the MultispeQ-Beta device. This work was supported by Grants PICT 2014-2496 and PICT 2015-3828 from the National Agency for the Promotion of Science and Technology (ANPCyT, Argentina), by PIP 1075 from the National Research Council of Argentina (CONICET), by the Federal Ministry of Education and Research (BMBF, Germany), and by the Project Management Juelich (PTJ, Germany). RG is a Fellow of the Bunge & Born Foundation. NC and AFL are faculty members of the School of Biochemical and Pharmaceutical Sciences, University of Rosario (Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Argentina) and staff members of the National Research Council (CONICET, Argentina).
The funding were provided by National Agency for the Promotion of Science and Technology (PICT 2014-2496 and PICT 2015-3828), National Research Council of Argentina (PIP 1075), Federal Ministry of Education and Research and Bundesministerium für Bildung und Forschung.
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