The genetic diversity of the Galanthus L. species in Turkey

Abstract

Galanthus L., widely known as snowdrops, is a genus of bulbous monocotyledons, consisting of 19 confined species. It belongs to the family Amaryllidaceae. The genus is confined to Europe, Asia Minor, and the Near East. There are about a dozen Galanthus species in Turkey, some of which are endemic to Anatolia. However, the identity and the taxonomic status of some of the species in Turkey are still unclear. In this thesis, a molecular phylogenetic approach is used including both the ITS-based phylogenetic method and amplified fragment length polymorphism (AFLP) to study the genetic diversity of the Galanthus species in Turkey. DNA sequencing of the nuclear ribosomal DNA gene cluster presents both intra-genomic uniformity and inter-genomic variability sufficient to construct a satisfying parental relationship within the genus. In addition to the nuclear ribosomal DNA intragenic spacer region (ITS1, ITS2 and 5.8S rDNA), chloroplast trnL(UAA) intron sequences, and the intergenic spacer between trnL(UAA) 3’ and trnF(GAA) 5’ genes are also studied. Phylogenetic trees constructed using this data showed that species of the same geography clustered together, in contrast to the presently recognized taxonomy based on morphological characters. In particular, the taxonomical status of G. alpinus, G. krasnovii and G. trojanus displayed significant differences compared to classification table based solely on morphology. A few closely related species which are indeed morphologically distinct but overlapping in their geographical distribution remained indistinguishable with the nuclear and chloroplast markers used. At this point, a second molecular tool, AFLP, proved to be a powerful technique in comparing several loci polymorphisms within the genome simultaneously. AFLP has been optimized and applied for the first time in this thesis not only for the phylogenetic studies of the Galanthus species but also for the Amaryllidaceae family. Optimization assays yielded satisfactory results in terms of fragment size and peak quality obtained on electropherograms. Application of this technique to a larger number of specimens to be collected from different altitudes and sites, would ascertain the identity and taxonomic status of the Galanthus species in question. Furthermore, within this study, the sequencing data for rDNA have been used to develop restriction assays to identify various Galanthus species. Molecular data presented in this thesis allow the application of a quick and a reliable method for distinguishing many endangered species from abundant and legally tradable bulbs.