Genetic Diversity and Phylogenetic Analyses of Juglans regia L. (Juglandaceae) Populations Using RAPD, ISSR Markers and nrDNA ITS Regions

Abstract

In this study, genetic diversity and phylogenetic analysis of Turkish Juglans regia L. populations was conducted based on random-amplified polymorphic DNA (RAPD) and inter-simple sequence repeat polymerase chain reaction ISSR-PCR and nuclear ribosomal DNA internal transcribed spacer (nrDNA ITS) sequences. A total of 14 populations from the Aegean and Marmara regions were included in the research. In all, 12 RAPD and 13 ISSR primers were used for molecular characterization of the J. regia populations. For the amplification of the nrDNA ITS region, ITS4 and ITS5A primers were used in PCR. In RAPD-ISSR-PCR analysis, a total of 55 and 85 bands were obtained, respectively. RAPD and ISSR analyses detected high polymorphism (74.54% and 70.57%, respectively) among J. regia populations. However, ITS sequence analysis was not efficient in revealing the genetic relationship among J. regia samples. In addition, phylogenetic analyses including nrDNA ITS sequences of our populations and that of other Juglans taxa (J. hindsii, J. major, J. nigra, J. microcarpa, J. cathayensis and J. hopeiensis) obtained from the National Center for Biotechnology Information (NCBI) were conducted. Analysis of J. regia populations based on RAPD and ISSR-PCR and ITS sequences revealed that the rate of polymorphism obtained with the ISSR-PCR approach was higher than those obtained using the ITS sequences and RAPD-PCR. Genetic diversity results of these populations will contribute significantly to the identification and breeding programs of walnuts.