Generation and characterization of plants expressing flavodiiron proteins to increase biomass yield

In eukaryotic photosynthetic organisms the excitatory interaction between light and pigments associated with photosystems I and II provides the driving energy for Linear Electron Flow (LEF) to occur, culminating in the production of reducing equivalents and in the generation of an electrochemical gradient across thylakoid membranes. To dynamically respond to environmental changes and metabolic requirements, photosynthetic organisms evolved several alternative electron flows like the Cyclic Electron Flow (CEF) and pseudo-Cyclic Electron Flow (pseudo-CEF, or water-water cycle). Flavodiiron proteins (FLVs) divert electrons coming from PSI to reduce water, and previous studies have demonstrated the role of FLVs in protecting PSI from photodamage upon sudden changes in light intensity in bryophytes. However, FLVs are absent in Angiospermae, and their reintroduction may serve as an instrument to increase the efficiency with which the photosynthetic machinery adapts to fluctuations in light intensity. To test this hypothesis, flv genes from the bryophyte Physcomitrium patens were successfully expressed in Nicotiana tabacum and physiologic parameters were assessed. In addition, transgenic Solanum lycopersicum plants expressing FLVs were obtained. Data presented in this work suggest that FLVs are functional in Angiospermae, protecting PSI from overreduction in the first instants after sudden increases in light intensity and enhancing their growth in fluctuating light conditions.