Genetic and Micromorphological Diversity in Sambucus ebulus (Adoxaceae) Populations and Their Taxonomic Significance.

Sambucus ebulus is mainly distributed in the northern, northwestern, and northeastern regions of Iran and is characterized by its perennial growth habit and the characteristics of long, creeping, and branched rhizomes. In the present study, the genetic diversity of seven populations of S. ebulus based on molecular ISSR data and as well as the micromorphology of seeds and leaves in nine populations of this species in Iran was investigated. The AMOVA (analysis of molecular variance) test showed that 87% of the total genetic variance was due to genetic differences among populations, while 13% was due to genetic variability within populations, indicating a high degree of genetic variation among S. ebulus populations. The discriminatory power of ISSR (Inter Simple Sequence Repeat) loci, determined by analyzing Gst against Nm (the number of migrants), showed that almost all ISSR loci have excellent discriminatory power. Thus, ISSR markers are effective in differentiating the studied S. ebulus populations. The Mantel test showed a significant correlation between genetic and geographic distance. In addition, it demonstrated the isolation mechanism responsible for the population structure in the S. ebulus plant populations. The micromorphological study revealed that the stomata are anomocytic and the epidermal cells of the different S. ebulus populations have irregular cell shapes with anticlinal walls ranging from straight to curved. The seed shape was described as predominantly almond-shaped, and the surface of the seed coat of the studied taxa showed a reticulate pattern. Our findings not only demonstrate a considerable degree of genetic diversity among populations of S. ebulus, but also emphasize the importance of micromorphological traits for understanding this species. This study provides a foundation for future research on the ecological importance and conservation of S. ebulus in Iran.