"Time-nested acclimation to excitation pressure: the transcriptome, proteome and phosphoproteome"

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The ultimate source of the energy for almost all organisms on this planet is sunlight. The chloroplasts of plants and algae are crucial in linking all other living organisms to the sun through the ability to absorb, trap, and transform this light energy to reduce CO2 to complex carbohydrates. This requires the integration of extremely fast, temperature-insensitive photochemical reactions to trap the energy with much slower, temperature-dependent metabolic processes that consume this energy. As a consequence, photosynthetic organisms are predisposed to exhibit an imbalance in cellular energy budget which can be quantified in vivo as excitation pressure (EP). Exquisite solutions to the problem of cellular energy budget reflect part of the magic of photosynthesis and are the result of the dynamic capacity of plants and algae to remodel the structure and function of the photosynthetic apparatus to an ever-changing environment in order to maintain an energy balance by minimizing EP. The long-term objective of my research programme is to elucidate the molecular basis by which plants and algae sense and respond to short-term changes in EP due to alterations in environmental light and temperature conditions and integrate this information over time to remodel the photosynthetic apparatus and generate a phenotypic change during long-term, steady-state acclimation and adaptation to EP. The proposed research will identify the nature and number of potential molecular sensors of EP present within chloroplasts and the mechanism(s) by which these sensors alter not only the structure of the photosynthetic apparatus but also the phenotype of the model plant, Arabidopsis thaliana. This will be combined with research that exploits the unique photosynthetic apparatus of a novel, cold-adapted, non-model, Antarctic green alga, Chlamydomonas raudensis UWO241, to elucidate the dynamic mechanism by which it regulates photosynthetic electron flow to modulate EP. The proposed research will alter our conventional view of the structure and function of the photosynthetic apparatus, not only as a dynamic global cellular energy sensor but also as a dynamic energy transformer.