Photosynthetic organisms convert physical energy from the sun into chemical energy through photosynthetic light reactions catalysed by thylakoid membrane-embedded pigment-protein complexes. Four major protein complexes — Photosystem (PS) II, PSI, cytochrome (Cyt) b6f, and ATP synthase — transform light energy into chemical energy via electron transfer and proton translocation reactions, releasing O₂ as a byproduct. The chemical energy produced in the form of NADPH and ATP is further utilized in carbon assimilation reactions, where CO₂ is metabolized into carbohydrates that serve as substrates for various metabolic processes.

Photosynthesis in plants takes place in chloroplasts, which are endosymbiotic evolutionary descendants of cyanobacteria. Chloroplasts are characterized by triple membrane system, from which the thylakoid membrane contains a unique, highly dynamic structure that is regulated according to environmental cues. Short-term changes in ambient conditions leads to adjustments in the membrane ultrastructure and its components, whereas prolonged exposure to environmental changes initiate acclimatory responses requiring alterations in the stoichiometry of photosynthetic complexes. Both, short-term regulatory mechanisms and long-term acclimatory responses are necessary for fluent photosynthesis while minimizing damage to photosynthetic apparatus. In addition to leaf tissue, also other green parts of the plant contain chloroplasts and conduct photosynthesis adapted to the specific cellular functions, thus contributing to the overall yield.

I have investigated the acclimatory and adaptive characteristics of photosynthetic machinery in the model species Arabidopsis thaliana. I demonstrate that light-induced dynamic regulation of the thylakoid membrane requires GNAT2, a chloroplast-located acetyltransferase, previously shown to play a crucial role in maintaining balanced excitation energy distribution between PSII and PSI. I also show that Arabidopsis stems contain high amount of PSI-NDH-complex that enhances ATP production, presumably to meet the metabolic requirements of the organ. Last, I reveal that the Cyt b6f complex is downregulated upon daily heat stress, highlighting the dynamic nature and acclimation capacity of the photosynthetic machinery.