Türkiye’de doğal yayılış gösteren astragalus l. cinsine ait altı seksiyonun (Halicacabus, Megalocystis, Macrophyllium, Hymenostegis, Hymenocoleous, Poterion) arasındaki kloroplast ve nükleer DNA bölgelerine dayalı moleküler filogenetik analizleri.

The thirty species involved in six Astragalus sections were studied not only to understand phylogenetic relationships and also to estimate evolutionary divergence times by using the DNA sequences of cpDNA (chloroplast) and nDNA (nuclear) regions. The results showed that the DNA sequences of ITS nr (nuclear ribosomal) region had with the highest genetic diversity. Based on all studied regions, Poterion section was the most diverge section than others while Megalocystis and Halicacabus sections were the closest ones. Moreover, A.vaginans from Hymenocoleous section was located also close to Hymenostegis section but always in different branch. It is notable that, A.dipodurus and A.oleaefolius species from Macrophyllium section placed in a different sub-branch in all phylogenetic trees constructed by both studied cpDNA and nDNA regions. iv To understand the phylogenetic relationships among the Turkish Astragalus species and in other regions of the world, DNA sequences of studied regions and foreign samples obtained from NCBI database were analyzed together. Turkish species formed a separated cluster, but close to Old world species in the phylogenetic trees of both trnL, matK and ITS regions. Moreover, some Old world species like Chinese, Australian and Korean were in close association with New world species. From all these results, it can be said that although Turkish species were derived from an independent diversity cluster. Evolutionary divergence time for Astragalus genus was estimated. All analysis depicts that studied sections of Astragalus genus that are native to Turkey were diverged from other New and Old world ones at Pleistocene period. According to two different cpDNA regions (trnL and matK), results indicated that Poterion section appeared to be newly diverged from other sections of Turkish Astragalus sections.Ph.D. - Doctoral Progra