Organisation, expression and evolution of rRNA genes in plant genomes

Abstract

Here we present an overview on the results of eight years of research line devoted to the organisation, expression and evolution of rRNA genes in plant genomes. We describe how we discovered a new rDNA arrangement in genus Artemisia, which includes all rRNA genes in a single unit (L-type). This was the first time that such organisation was found in seed plants. We further explored family Asteraceae in depth, to which Artemisia belongs, to find that the L-type arrangement may be present in about 25% of its species. Later on we move to gymnosperms to describe the landscape of rRNA arrangements in a representative sample of its diversity. We assess the expression rate of the L-type rRNA in several L-type species, which is comparable to that of species with separated arrangement of rRNA genes (S-type). Finally, we present the resource www.plantrdnadatabase.com which includes information on type of rDNA arrangement, number and position of rDNA loci in plants.