Vernalization-Triggered Intragenic Chromatin Loop Formation by Long Noncoding RNAs

Long noncoding RNAs (lncRNAs) affect gene regulation through structural and regulatory interactions with associated proteins. The Polycomb complex often binds to lncRNAs in eukaryotes, and an lncRNA, COLDAIR, associates with Polycomb to mediate silencing of the floral repressor FLOWERING LOCUS C (FLC) during the process of vernalization in Arabidopsis. Here, we identified an additional Polycomb-binding lncRNA, COLDWRAP. COLDWRAP is derived from the repressed promoter of FLC and is necessary for the establishment of the stable repressed state of FLC by vernalization. Both COLDAIR and COLDWRAP are required to form a repressive intra-genic chromatin loop at the FLC locus by vernalization. Our results indicate that vernalization-mediated Polycomb silencing is coordinated by lncRNAs in a cooperative manner to form a stable repressive chromatin structure.