Genetic diversity of castanea sativa an endangered species in the hyrcanian forest

Castanea sativa Mill. is one of the most endangered tree species in Iran where it is represented by small fragmented populations in the north of the country. 18 simple sequence repeat (SSR) loci (10 nuclear and 8 chloroplastic) were used to evaluate the genetic diversity and population structure of C. sativa from the Hyrcanian forest. For nuclear SSR, the number of alleles detected per locus ranged from 1 to 5 and observed heterozygosity (HO) was between 0.125 and 1.000. Analysis of molecular variance (AMOVA) indicated a high level of variation within populations (84%) and low levels between populations (16%). Based on structure analysis, the four studied populations were divided into two main clusters that have genetic distance Fst = 0.3. The Shafaroud population was separated in the first cluster, Siyahmazgi, Qalehroudkhan and Veysroud were placed in the second cluster. The UPGMA analysis confirmed the results of Structure analysis, separating the Shafaroud population from the others. The 8 chloroplast SSR loci used to screen the populations showed no polymorphism. In General, low nuclear genetic diversity, no polymorphism in cpDNA and considerable genetic differentiation among populations in short geographical distance represent a serious genetic erosion threat for C. sativa in the Hyrcanian forest, even hinting at an ongoing extinction vortex. Therefore, due to significant decline in genetic diversity, it is essential to introduce constraints protection upon the areas of distribution of all four populations of this species in Iran.