Genetic diversity and essential oil composition of Myrtus communis L. from Lorestan Province, Iran: Implications for conservation and utilization

This study investigates the relationships between genetic diversity, environmental factors, and essential oil composition in Myrtus communis L., an evergreen medicinal shrub. Three populations in Lorestan Province, Iran (Cham Mord, Kaka Reza, Sepid Dasht) were analyzed using molecular and chemical techniques. Genetic diversity was assessed using Inter-Simple Sequence Repeat (ISSR) and Start Codon Targeted (SCoT) markers. ISSR (eight primers, 81 loci) showed highest diversity in Cham Mord (Shannon I = 0.26), while SCoT (eight primers, 71 loci) indicated Kaka Reza had highest diversity (I = 0.27). PCoA and cluster analysis under both markers showed Cham Mord was genetically distinct, with lowest genetic distance between Kaka Reza and Sepid Dasht (0.259) and highest between Cham Mord and Sepid Dasht (0.332). Gas Chromatography-Mass Spectrometry identified 37 essential oil compounds with significant variation. Cham Mord had higher α-pinene (72.05%) than Kaka Reza (22.45%) and Sepid Dasht (6.56%). Sepid Dasht showed highest oil yield, linked to lower altitude, higher phosphorus (13.8%) and organic carbon (1.24%), and lower salinity (EC = 0.24 ds m-1). Kaka Reza, with higher salinity (EC = 0.41 ds m-1) and sodium (19 mg l-1), had the lowest yield. Essential oil-based clustering grouped Cham Mord and Kaka Reza, separating Sepid Dasht, matching SCoT patterns. Results reveal strong correlation between genetic diversity, oil profiles, and environmental factors including altitude, salinity, sodium, phosphorus, and organic carbon. Altitude inversely related to oil yield. Findings highlight local adaptation and phenotypic plasticity in M. communis chemodiversity, offering insights for conservation, sustainable use, and selection for medicinal and agricultural uses. Further studies on gene expression mechanisms of oil biosynthesis under varying environments are recommended.