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 remain uncharacterized. Here, using a combination of long- and short-read sequencing technologies we assemble contigs of the Arabidopsis NOR2 rDNA domain. We identify several expressed rRNA gene variants which are integrated into translating ribosomes in a tissue-specific manner. These findings support the concept of tissue specific ribosome subpopulations that differ in their rRNA composition and provide insights into the higher order organization of NOR2.

尽管生物体之间存在巨大差异，但它们基因组的一些特征是保守的，例如核仁组织区 (NOR)。NOR 由多个高度重复的 rDNA 基因组成，编码从 45S rDNA 单元转录的催化核糖体核心 RNA。它们精确的序列信息和组织仍然没有特征。在这里，使用长读长和短读长测序技术的组合，我们组装了拟南芥NOR2 rDNA 域的重叠群。我们鉴定了几种表达的 rRNA 基因变体，它们以组织特异性方式整合到翻译核糖体中。这些发现支持组织特异性核糖体亚群的概念，它们的 rRNA 组成不同，并提供了对 NOR2 更高阶组织的见解。