Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina.
Departamento de Química Biológica (QB 23), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (UBA), C1428EGA, Buenos Aires, Argentina.
Photosynth Res. 2018 May;136(2):129-138. doi: 10.1007/s11120-017-0449-9. Epub 2017 Oct 11.
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.
在田间生长的植物由于云、其他叶子等造成的遮荫效应，会经历辐射的急剧变化。过量的吸收光能通过多种机制耗散，包括循环电子传递、光呼吸和 Mehler 型反应。这种保护对于生存至关重要，但会降低光合作用效率。除了被子植物以外的所有光合生物都含有黄素铁蛋白（Flvs），它们通过将氧气直接还原为水来减轻光合作用电子传递链上的过剩激发能。将蓝藻的 Flv1/Flv3 引入烟草叶绿体中，导致转基因植物在稳态光照下表现出相似的光合作用性能，但在暗-光转换过程中，各种光合作用参数（包括电子传递和非光化学猝灭）的恢复更快。它们还使电子传递链保持在更氧化的状态，并增强了暗适应叶片的质子动力势。结果表明，Flvs 在光过渡期间充当电子汇，有助于在田间植物所经历的变化环境条件下提高光合作用的保护和效率。
