Essential oil compounds of endemic Centaurea kurdica Reichardt from Turkey

Abstract

Oaks with 18 species are the most widespread and diverse angiosperm-tree genus in the Turkey and cover the area of 6.5 million ha. Although HEDGE and YALTIRIK (1982) simplified the taxonomy of Turkish oaks by reducing the number of taxa, the taxonomical, biogeographical and phylogenetic status of oaks are not clear yet. Due to widespread natural hybridization among oak species, taxonomic delimitation of species with conventional approaches is complicated. Thus, we studied the phylogenetic relationships of the native oak species in Turkey by using evolutionarily conserved regions of nuclear (nDNA) (ITS) and chloroplast (cpDNA) (trn, matK) genomes. Among the studied regions, ITS region had the highest variable sites (188) and nucleotide diversity (0.032) in Turkish oaks compared to two ther regions of cpDNA. The variable site and diversiy were 42 and 0.0028 in trn and 33 and 0.0021 in matK, respectively. Of the three oak sections, Ilex section was the most diverse with respect to varaible sites and nucleotide diversity. The Cerris section had the lowest nucleotide diversity (ranged from 0.00056 in trn to 0.026 in ITS). The existence of variable sites and nucleotide diversity was influenced by the natural hybridization among species of oak sections. Quercus cerris in Cerris section, Quercus petraea and Q. pubescens in Quercus section seem to contribute greatly to the gene pool of Cerris and Quercus sections, respectively. Although oak forests in Turkey play vital role in sustainable agriculture, range management, and forestry in changing climate, they did not attract foresters and conservation biologists as much as they deserve so. Thus, oak forests in Turkey require well planned and structured genetic resource conservation programs. Especially, dynamic in situ conservation programs for priority species and areas which will be based on genetic information and genetic refugia should be initiated in Turkey. The further implication of genetic resource conservation in oaks with respect to climate change and oak forestry will be provided in the presentation