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Genetic differentiation of Liquidambar Orientalis Mill. varieties with respect to matK region of chloroplast genome

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2007
Özdilek, Aslı
Liquidambar L. genus is represented with mainly 4 species in the world and one of these species, Turkish sweet gum (Liquidambar orientalis Mill.) which is a relictendemic species is naturally found in only southwestern Turkey, mainly in Muğla Province. The limited distribution of species with two disputed varieties (var. integriloba Fiori and var. orientalis) and increased anthropogenic threats to its genetic resources signify the importance of studying genetic diversity in the species to have better conservation and management programs. For this purpose, 18 different populations were sampled throughout the species range and matK region of chloroplast DNA (cpDNA) was sequenced to assess the genetic structure of the species. Turkish Liquidambar orientalis populations were evaluated at two categories: variety level and geographic level. Also, two sectors of matK region were examined to assess which part of the region was more variable. All molecular analysis was conducted in this study by using MEGA version 3.1 and Arlequin 2.000 softwares. v Moleculer diversity analysis indicated that the population located in Fethiye- Günlükbası district has the highest number of polymorphic sites. This population is also genetically the most distant from the others (average genetic distance 0.0038). Among the studied varieties, the average genetic distance within var. integriloba (0.0016) which also includes population Fethiye-Günlükbası was the greatest. Among the geographic regions, Muğla-1 including Fethiye-Köyceğiz-Aydın district as well as population Fethiye-Günlükbası showed the highest average genetic distances within the region with a value of 0.0015. According to the molecular variance results, among varieties and among geographic regions, there was no significant differentiation, but great amount of total variation was found (~86%) within Turkish sweet gum populations. With respect to the Fst values among varieties, the highest genetic differentiation was observed between var. orientalis and unknown group (0.040). Furthermore, based on the results of phylogenetic analysis, Turkish populations of L. orientalis have genetically closer to USA relative (L. styraciflua L.) than Chinese relatives (L. acalycina H.T Chang and L. formosana Hance). In conclusion, 10 Turkish sweet gum populations were found to be important for conservation issues. Furthermore, eight of these located in Muğla province and sixth of them belong to var. integriloba. Especially Fethiye-Günlükbası, MarmarisÇetibeli and Muğla-Kıyra populations should be included in either insitu or exsitu or in both conservation programs in the future.