Polycomb Repressive Complex 2 (PRC2) is an evolutionarily conserved histone methyltransferase complex that catalyses trimethylation of lysine 27 of histone H3 (H3K27me3), which leads to epigenetic gene repression. In Arabidopsis thaliana (A. thaliana), CURLY LEAF (CLF) and SWINGER (SWN) are two major H3K27 methyltransferases and core components of PRC2 in the sporophyte, playing essential roles in the regulation of plant development. However, the knowledge of how PRC2 participates in operational control in plants is scarce. Recently, altered phenotypes of PRC2-depletion mutants grown under different light intensities were observed. Hence, here I raise the hypothesis that PRC2 acts in fully differentiated cells to modulate the ambient light acclimation. At first, short- and long-term light acclimation responses that require PRC2 activity will be identified, employing plant morphology and physiology tools. Next, PRC2-governed molecular mechanisms and PRC2-modulated light signaling pathway in the light acclimation will be established. Molecular tools (RNA-seq and ChIP-seq) will be used to profile transcriptome and H3K27me3 distribution to establish the patterns of epigenome and transcriptome alteration in WT and mutants. At last, the focus will expand to select other chromatin modification mutants displaying altered light acclimation responses. In summary, for the first time, dynamics of PRC2 repression in fully differentiated cells in response to light acclimation will be determined and it will lay a solid foundation for studying other chromatin modifiers in future. The project builds on combining my experience in plant physiology and ecology and gaining research experience in the field of developmental epigenetics. The fellowship proposal is designed in a way to enhance my independent thinking capacity, organizational and management skills and responsibilities, which are necessary to become an excellent and independent researcher and group leader in the future.