Sarah Leuchtenberg (Universität Hohenheim)
Sarah Frankziska Leuchtenberg's Master thesis was awarded with the Prize for the Best Plant Science Master Thesis, which was carried out at Hohenheim University in the year 2025 with the title:
Analysis of the regulation of chromatin organisation in A. thaliana by PDS5A
This study demonstrates for the first time that the TAD-like domains suppressed by PDS5A in Arabidopsis thaliana are regulated by cohesin subunits and cofactors, which differs from other plants.
In addition to the linear DNA sequence and the epigenetic landscape, genome function is also determined by its non-random, three-dimensional organization within the nucleus. This organization includes topologically associating domains (TADs), which are widespread in animals and many plant species and are regulated in animals by the cohesin protein complex. The model plant Arabidopsis thaliana, however, represents a special case within the plant kingdom, as TADs are largely absent in the wild type. After the underlying reason remained unclear for a long time, it was shown in 2024 that the cohesin-associated protein PDS5A actively suppresses TAD formation in Arabidopsis, such that TADs become prominent in the pds5a mutant.
The aim of this work was therefore to investigate the role of PDS5A and related cohesin regulators in the formation and stability of TADs in Arabidopsis. Hi-C analyses across different tissues first revealed that TADs in pds5a occur largely independently of tissue identity and gene activity. To identify additional molecular actors involved in TAD formation, a screen based on long-read Oxford Nanopore sequencing was established, enabling rapid detection of chromatin structural changes in further mutations on the pds5a background. This revealed that additional cohesin-associated proteins, such as SYN4 or WAPL, significantly influence chromatin structure, similar to observations in animal models. In addition to TADs, so-called “architectural stripes” were examined; in animal systems, these stripes are indicative of active cohesin extrusion, and their occurrence in Arabidopsis likewise points to cohesin-driven mechanisms.
Overall, this work provides new insights into 3D genome organization in plants and establishes the pds5a mutant as a promising model for studying cohesin-dependent mechanisms in plants. In the long term, it enables the elucidation of both evolutionary conservation and plant-specific strategies of 3D genome organization and their regulatory roles in plant growth and development.
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Sarah F. Leuchtenberg conducted this work at the institute of biology in the working group of Jun.-Prof. Dr. Chang Liu.
