Genetic diversity of Tamarix ramosissima populations according to ISSR markers

Abstract

Branched Tamarix (T. ramosissima Ledeb.) is a shrub widely used for agroforestry of arid territories. The aim of the research was to determine the genetic variability of 8 populations of T. ramosissima Ledeb., growing in the arid conditions of Southern Russia. A total of 138 plants were selected for the study. The geographical distance between populations within the same region was: 23 km (Stavropol region); 30 km (Astrakhan region); 170 km (Republic of Kalmykia). The analysis of the genetic structure was carried out using 11 ISSR markers. A total of 189 DNA fragments were amplified. The obtained PIC values (from 0.248 to 0.330) indicate the high diagnostic value of the ISSR primers involved in the work. A high level of polymorphism was found in all the studied populations, with an average of 92.6 %. The highest percentage of polymorphic loci was observed in the Tr_a2 population (Astrakhan region, 97.9 %), and the lowest in Tr_k1 (Republic of Kalmykia, 87.3 %). The na and ne values ranged from 1.44–1.59 and 1.25–1.33, respectively, with average values of 1.52±0.499 and 1.28±0.346. The Nei’s genetic diversity index ranged from 0.150 to 0.198, with an average level of 0.166±0.188. The Shannon’s index varied from 0.232 to 0.300, averaging 0.254±0.272. To assess the degree of genetic divergence of populations growing in different regions, the coefficients of the Nei’s genetic distance were calculated. The constructed dendrogram confirms the high level of genetic diversity of T. ramosissima populations. The absence of clustering by regions shows that the genetic differentiation of the studied species is largely determined not only by the current geographical distance, but also by other factors, such as adaptive features to habitat conditions.