Molecular differentiation of Turkish and Common hazels (Corylus colurna L. and Corylus avellana L.) using multiplexed nuclear microsatellite markers

Corylus colurna is considered as important tree species under climate change for dry and warm conditions in Central Europe and was overused because of its valuable wood. Therefore Turkish hazel is now present only in small isolated populations and is protected under IUCN. Genetic conservation of this tree species plays a key role in future sustainable forest development. Turkish hazel co-occurs with Common hazel (C. avellana) in its whole distribution area and may form hybrids. To differentiate between the pure species and their hybrids, cross-species amplifying markers are required. In this study we have evaluated existing simple sequence repeat (SSR) markers using altogether 128 samples of C. avellana and C. colurna. Fifteen nuclear SSRs have generated easy to-score alleles in the two species and 13 of them were highly polymorphic. For  all 15 markers the mean allele number, average observed heterozygosity, genetic diversity and polymorphism information index were high. The two most polymorphic SSRs were L1.10 and CaT-B501 with 19 and 16 alleles, respectively. Structure analysis proved the differentiation of the two species C. avellana and C. colurna. No hybridization was detected in the analysed populations. Results also indicated that C. colurna from Balkan Peninsula and Asia Minor belong to separate groups. Our study presents highly polymorphic, easy to score, ready to use SSR-multiplexes, which can be applied in population genetics and gene conservation studies.