In eukaryotes, genomic DNA in interphase nuclei shows non-random distribution patterns with respect to sub-nuclear space including the nuclear periphery (NP). It is functionally equivalent to animal lamins, playing critical roles in modulating patterns of chromatin positioning at the nuclear periphery. In summary, we conclude that CRWN1 is a key component of the lamina-chromatin network in plants. Furthermore, ChIP-seq analysis indicates that CRWN1 directly interacts with chromatin domains localized at the nuclear periphery, which mainly contains non-accessible chromatin. With chromosome painting and Hi-C analyses, we show global attenuation of spatial chromatin compartmentalization and chromatin positioning patterns at the nuclear periphery in both the crwn1 and crwn4 mutants. ResultsД«y conducting dual-color fluorescence in situ hybridization experiments on 2C nuclei, we show that in Arabidopsis thaliana, specific chromatin positioning at the nuclear periphery requires plant lamin-like proteins CROWDED NUCLEI 1 (CRWN1), CRWN4, and DNA methylation in CHG and CHH contexts. To date, how plants manage to selectively tether chromatin at the nuclear periphery is unclear.

For both plants and animals, the nuclear periphery is a functional compartment enriched with heterochromatin. The nuclear envelope not only serves as a physical barrier separating nuclear content from the cytoplasm but also plays critical roles in modulating the three-dimensional organization of genomic DNA.