RibosomalRNA Gene Spacers as DNA Barcodes and Prelude of RibosomalRNA Gene Evolution in GenusPlantago

Abstract

The importance of spacer regions in resolving the phylogenetic questions using a combination of molecular and cytological techniques illustrates the importance of spacer regions in determining the phylogeny of genus Plantago and in assigning them the name of gene relics in the pretext of evolution. 74Plantago and representative out-group tax a were chosen for sequence analysis of spacers of the ribosomal deoxyribonucleic acid (DNA) to evaluate their phylogenetic potential. The chromosome number of different species of the genus was matched in accordance to their positions in the phylogenetic tree with an aim to work out a reasonable resolution of sub-generic groups as recognised earlier. Internal transcribed spacer (ITS) sequences of 67 species from the GenBank showed a distinct 21base pair conserved motif within the ITS1 region, which was used for barcoding of different species of Plantago, which was further supported by developing a Polymerase Chain Reaction – Restriction fragment length polymorphism (PCR-RFLP) -based technique to help in the process of barcoding. The homology between the spacer region and the coding region of 5S ribosomal ribonucleic acid (rRNA), from various genera and species ascertained that these regions represent gene relics and constitute essential players in the regulation of rRNA genes contiguous to these sequences.