CHARACTERIZATION OF ITS1 SECONDARY STRUCTURE IN TEN SPECIES OF COLUTEOCARPEAE (BRASSICACEAE) AND ITS TAXONOMICAL UTILITY

Abstract

Utility of the internal transcribed spacers (ITSs) of ribosomal RNA sequences to infer phylogenetic relationships among organisms have been proven. Although ITS1 and ITS2 are highly variable in sequence, they have conserved structures that have a key function in the processing of rRNA gene transcripts. Determining of such a conserved motif can help to identify relationships between organisms. Since ITS2 has much more conserved secondary structure, structural properties of ITS1 are generally neglected by researchers. In this study, ITS1 secondary structures of ten representative species, which were once assigned under different genera, of tribe Coluteocarpeae were determined. Also taxonomical utility of ITS1 secondary structure was also tested. Analyses indicate that there are four different types (4-, 6-, 7- and 8 hairpin) of secondary structures. On the other hand, each sequences have a conserved region that is common among land plants. Since previous studies reveals other species, that belong different tribes or lineages of Brassicaceae show similar ITS1 secondary structure, it is not a useful delimitation tool for investigated species in terms of taxonomy.