Molecular organization of 5S rDNA of Brunfelsia uniflora (Pohl.) D. Don

Abstract

Aim. The 5S rDNA represents a convenient model for studying of the molecular evolution of tandemly arranged repeated sequences. However, in many groups of angiosperms this genomic region still remains poorly studied. So far, in the family Solanaceae the 5S rDNA was described only for five genera. In order to elucidate the 5S rDNA organization in representatives of other genera of Solanaceae, we decided to explore organization of this region in Brunfelsia uniflora (tribe Petunieae). Methods. PCR amplification, cloning and sequencing of 5S rDNA. Results. Three clones of 5S rDNA of Brunfelsia uniflora were sequenced. It was found that only one class of repeats ranging in length from 343 to 347 bp is present in the genome of B. uniflora. The level of intragenomic similarity for the 5S rDNA intergeneric spacer regions (IGS) ranges from 86.7 to 96.4 %. The IGSs of B. uniflora and of other members of Solanaceae family differ significantly: the sequence homology was detected only for sequence motives required for RNA polymerase III transcription initiation and termination. Conclusions. The molecular evolution of the 5S rDNA IGS occurs at a high rate in the Solanaceae family. Accordingly, the comparison of the IGS should be used to clarify the phylogenetic relationship between taxa of low rank, in particular between species and genera of the tribe Petunieae. Keywords: 5S rDNA, intergeneric spacer, molecular evolution, Brunfelsia, Solanaceae.