Arabidopsis thaliana NOR2 sequencing

Despite vast differences between organisms, some characteristics of their genomes are conserved, such as the nucleolus organizing region (NOR). The NOR is constituted of multiple, highly repetitive rDNA genes, encoding the catalytic ribosomal core RNAs which are transcribed from 45S rDNA units. Their precise sequence information and organization remained un-characterized.We used long read in combination with short read sequencing to assemble contigs of the Arabidopsis NOR 2 rDNA domain providing a first scaffold . We identified several expressed rRNA gene variants which are integrated into translating ribosomes in a tissue specific manner. These findings led to the concept of tissue specific ribosome subpopulations differing in their rRNA composition.