Phenotypical, genetic structure, and essential oil characteristics of twenty Ocimum basilicum L. agro-ecotypic populations from Iran

Basil (Ocimum basilicum L.), belonging to the Lamiaceae family, is an important leafy aromatic herb that is widely cultivated throughout the world and used as a fresh vegetable and spice. In this study, genetic structure, agromorphological, and essential oil variability among twenty Iranian agro-ecotypic populations (AEPs) of the plant was studied to find adequate samples for further use in breeding and exploitation programs. For this purpose, the seeds of 100 individuals from AEPs were collected and cultivated in a completely randomized block design. Significant agro-morphological and essential oil diversity was found among the cultivated AEPs. The highest coefficient of variation was obtained in leaf color (39.25 %) and herb weight (36.65 %). The essential oil content varied from 0.34 to 1.95 w/w% among the studied samples characterized with methyl chavicol (19.9343.64 %) and geraniol (6.15-37.43 %) as the major compounds. A total of 101 bands were obtained from fourteen inter-simple sequence repeats markers (ISSR) used, of which 95 bands were polymorphic (6.79 %). The polymorphic information content for the primers varied from 0.08 (IS13) to 0.37 (UBC878). Analysis of molecular variance of AEPs revealed that 79.0 % of the variation was at the intra-population level, while the variation between populations was 21.0 %. The dendrogram based on ISSR markers showed a high diversity between the AEPs. Multiple regression analysis showed that ISSR bands had a significant correlation with phenotypical and essential oil characteristics. The extraordinary diversity in terms of the studied parameters indicates the ability of AEPs to be selected and used in breeding, cultivation, and production programs.