Function of cohesin ring complexes in the control of phytohormone-mediated stress response andchromatin structuring in Arabidopsis

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The three-dimensional genome architecture is decisive for the regulation of gene expression. Cytological and biochemical studies, together with genome-wide analyses, have identified multiple molecular factors, such as chromatin insulators, Polycomb group complexes (PcG), and protein ring complexes to structure chromatin and regulate gene transcription in eukaryotes – with a variety of effects on the development and physiology of the organisms. For plants, compared to other eukaryotes such as yeasts and humans, our knowledge of the formation of genome structures is still rudimentary and there is much to suggest that plants, during evolution, have developed unique / additional molecular mechanisms of 3D genome packaging. The chromatin structure is very dynamic and changes according to cell types and cell developmental stages. Particularly strong is the change due to external stimuli. In plants, chromatin is reorganized in response to abiotic and biotic stress, which significantly contributes to the adaptation of gene expression. However, how the three-dimensional chromatin structure changes, especially the landscape of chromatin loops, and what role the loop-forming cohesin ring complexes play is not known yet. Early experiments with knockout mutants suggest that certain cohesins do indeed play a surprisingly strong role in responding to external stimuli in Arabidopsis. I intend to investigate the role of tripartite cohesin ring complexes in the formation and regulation of chromatin loops in vegetative plant cells. Here I put forward the hypothesis that cohesin ring complexes are a crucial factor for the plasticity and adaptability of the genome by controlling chromatin loop formation. They may be responsible for the formation and separation of gene clusters, the silencing of genes or the activation of transcription by enhancer elements, which is important to regulate all kinds of cellular processes, of which I am interested in the events that occur in response to abiotic and biotic stress in Arabidopsis.