Arabidopsis thaliana, chromatin positioning at the nuclear periphery. Arabidopsis thaliana

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. For both plants and animals, the nuclear periphery (NP) is a functional compartment enriched for heterochromatin. To date, how plants manage to selectively tether chromatin at the NP is unclear. By conducting dual-color in situ hybridization experiments on 2C nuclei, we show that in Arabidopsis thaliana, specific chromatin positioning at the NP requires plant lamin-like proteins CROWDED NUCLEI 1 (CRWN1) and CRWN4. In metazoans, the epigenetic mark, histone H3 lysine 9 methylation (H3K9me), is required for the anchoring of targeted chromatin at the NP; however, the loss of H3K9me has no effect in this regard in Arabidopsis. Instead, DNA methylation in CHG and CHH contexts turn out to be required for this process. With chromosome painting and Hi-C analyses, we show global attenuation of spatial chromatin compartmentalization and chromatin positioning patterns at the NP in both the crwn1 and crwn4 mutants. Furthermore, CRWN1 directly interacts with chromatin domains localized at the NP, which mainly contains transposable elements and silenced genes. In summary, we conclude that CRWN1 is a key component of the lamina-chromatin network in plants. It is functionally equivalent to animal lamins, playing critical roles in modulating patterns of chromatin positioning at the NP. This is a collection of raw sequencing data associated with: Hu B, Wang N, Bi X, Karaaslan ES, Weber AL, Zhu W, Berendzen KW, Liu C. Plant Lamin-like Proteins Mediate Chromatin Tethering at the Nuclear Periphery.