Analyses of genetic diversity and population structure of endemic and endangered species Sideritis gulendamii (Lamiaceae) and implications for its conservation

Sideritis gulendamii is a perennial, endangered plant endemic to Turkiye with narrow and fragmented populations encountered in gypsum and marl soil. This species is known as mountain tea and also has a significant potential for use for medicinal and aromatic purposes. Assessing the genetic diversity of this species holds significant importance in its conservation efforts due to its specific habitat requirements, small and isolated populations, and recent threats imposed on these populations. This study determined genetic diversity at the species and population levels using the inter simple sequence repeat (ISSR) fingerprinting method on 157 individuals from seven natural populations. We observed that the species-level genetic diversity is relatively high (H = 0.189, I = 0.298), but the population-level is low (H = 0.150, I = 0.231). The greater total genetic variation within populations was determined as 76% using the analysis of molecular variance (AMOVA). The obtained value of genetic differentiation (Gst = 0.208, phi pt = 0.24) among populations is considered to be at a moderate level, whereas gene flow appears to be high (Nm = 1.899). Supportive results were reached using the STRUCTURE cluster analysis, Unweighted Pair Group Method with Arithmetic Averages (UPGMA) dendrogram, and Principal Coordinate Analysis (PCoA). The positive correlation between the matrices of genetic distance and geographic distance is determined to be statistically significant, with values of r = 0.566 and p < 0.001 in the Mantel test. Some strategies were developed using the genetic variability pattern of this endangered species for its conservation.