#intergenicspacer

[cytgen]

Abstract The intergenic spacer (IGS) of 5S ribosomal RNA genes (5S rDNA) (that are present in the genome of all living organisms) is characterized by a high variability, due to which it is a convenient and widely used object for clarifying the issues of genome evolution, population genetics, systematics, etc. The aim of this work was to study the IGS of 5S rDNA of the Antarctic pearlwort Colobanthus quitensis. The nucleotide sequence was determined by the methods of molecular genetic analysis, and molecular organization of the C. quitensis 5S rDNA IGS was studied. It was demonstrated that it contains the regulatory elements typical for other vascular plants. The existence of at least two classes of 5S rDNA repeats in the individual genome (that differ significantly in the length and nucleotide sequence of IGS) was established. In addition, based on differences in the length and nucleotide sequence, two subclasses of repeats with a long IGS and three subclasses with a short IGS were identified. A comparison of 5S rDNA IGS sequences in C. quitensis and Silene latifolia Poir. (a member of another section of the Caryophyllaceae family) demonstrated significant differences in the structure of a spacer region of 5S rRNA genes (except for its parts containing regulatory elements). In general, data obtained indicate a significant level of intragenomic polymorphism of C. quitensis 5S rDNA IGS.