Genetic variation in white poplar (Populus alba L.) populations as characterized by SSR markers

Abstract

The white poplar (Populus alba L.), which is tolerant to abiotic and biotic stresses, is a tree species that is resilient against changing climatic and environmental conditions, which makes it a suitable candidate for afforestation efforts. However, due to pro-longed human intervention associated with the increasing population, the genetic resources of this species are at risk of loss. Addition-ally, while this species generally reproduces sexually, reproduction clonally via its root suckers has become widespread in some areas. Hence, the aim of this study was to investigate the genetic diversity of white poplar, which is increasingly experiencing genetic diversity loss. Herein, 15 different populations distributed overall in Turkiye were sampled, and the genetic structure and diversity of the spe-cies were examined using 10 simple sequence repeat molecular markers. The analyses revealed relatively high levels of genetic varia-tion in the populations (observed heterozygosity: 0.50, expected heterozygosity: 0.46) and the molecular variance analysis determined 84% genetic variation within the populations. Overall, the distance between the populations decreased, the gene flow (Nm) increased, and the genetic differentiation decreased (Nm: 0.16-30.24, gene differentiation coefficient: 0.01-0.61). The principal component and phylogenetic analyses data also supported these results. The 3 populations at the highest altitude, Erzurum-Oltu, Kayseri-Akkoy, and Konya-Meram, had a different genetic structure than the others. Furthermore, clonal reproduction was intensive in some populations together with the inclusion of human activities, and therefore, the genetic diversity of the species decreased. However, the white poplar populations in riverside and floodplain forests had higher genetic diversity and private alleles. For this reason, the Eskisehir-Porsuk cayi and Samsun-Bafra populations could be recommended for in situ conservation of white poplar. This study provides information on the genetic diversity of white poplar populations in Turkiye, and thus contributes to more efficient and rational planning of breeding and conservation programs for the species.