Organization of the 5S rRNA gene units in Korean Lilium species

Abstract

The 5S rRNA gene unit was characterized from Lilium species distributed in Korea. Sequence analyses revealed that the 5S rDNA, harboring a highly conserved coding region (120 bp) and a divergent non transcribed spacer (NTS), ranged from 470 bp to 640 bp. The NTS regions showed length heterogeneity (350 bp–520 bp) due to the presence of several indels, and extensive sequence divergence among the species. Despite heterogeneity in length and nucleotide composition, the NTS regions possess some common features across the species, which include a T stretch region CTTTT and an identical motif of 11 bp (CAATGTATGAC) at the 3′ and 5′ flanking sequence of the coding region, respectively. These may play a role in the initiation and termination of transcription. The chromosomal distribution of the 5S rRNA gene was mapped on the long arm of chromosome 3 by fluorescence in situ hybridization (FISH). The phylogenetic analysis based on the NTS sequence broadly divided the Lilium species into two major groups which were referred to as the section Sinomartagon and Martagon by Comber’s classification of the genus Lilium. The present study showed that the 5S rDNA sequence was very useful to unravel the genetic relationships among Lilium species.