Date

2021-1-3

Author

Nebioğlu, Nehir

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Populus euphratica, one of the four Populusspecies naturally distributed in Southern and Southeastern Turkey, can survive under extreme conditions like high temperatures, low moisture, salty and calciferous soils. P. euphratica carries great significance for both the sustainability of a healthy river ecosystem and the supply of renewable energy resources. Meanwhile, due to the continuous increase in the human population, water resources decrease, and habitat destruction becomes unavoidable for this species. Recent studies confirm the reduction in the range of species and loss in its genetic resources. Thus, studying the magnitude and structure of the genetic diversity between genders held on great importance to generate information for the use of gene resources and effective conservation. In this study, the genetic diversity and genetic structure of female and male individuals in P. euphratica populations from the Göksu river ecosystem were studied with seven microsatellite markers (SSR: simple sequence repeats). The microsatellite markers were selected according to several sex-determination studies in Populus species. The existence of sex chromosomes in Populus species was proposed, yet the location of the sex‐determining region on the sex chromosome of P. euphratica has not been determined. Differentiation of sex at early stages of growth is exceptionally critical to developing the breeding strategies because the genetic diversity programs cannot be employed until the species reached the reproductive stage (10 to 12 years). Thus, generated data on gender related diversity and gender determination in this study have great importance for augmentation in breeding programs, genetic improvements, and conservation studies of P. euphratica. Among P. euphratica populations from the Göksu basin, private alleles were mostly found in male individuals. Most of the detected private alleles were found in the BPCA90 locus, which had male- and female-specific private alleles. Also, BPCA90 was also the most informative and effective locus in our study according to genetic diversity parameters. Genetic diversity analysis revealed no significant variation between female and male tree populations detected with the studied loci. Moreover, population structure analyses asserted that the gene regions have used for gender determination in several Populus species showed high similarity in female and male trees of P. euphratica populations in our study. There were two homogeneous gene pools observed in both genders with equal membership values. Different genders might be expressed by the same genotype of P. euphratica trees in our study, depending on the environmental factors. To continue breeding in adverse environmental conditions, these deviations from strict dioecism have been observed in several Populus species. The results of this study indicated considerably narrowed genetic diversity. According to effective population size analysis and calculated GW indexes, natural populations of P. euphratica species in the Göksu river appeared to have experienced severe past reductions in population sizes and are in danger of breakdown

Subject Keywords

Populus euphratica, Sex determination, Microsatellite markers, Genetic diversity, Genetic structure

URI

https://hdl.handle.net/11511/89672

Collections

Graduate School of Natural and Applied Sciences, Thesis