Metabolic diversity and genetic association between wild populations of Verbascum songaricum (Scrophulariaceae)

The Verbascum L. genus (Scrophulariaceae) is rich in phenols, flavonoids, and iridoid glycosides, which have been used extensively in traditional medicine. This study aimed to examine the association between genetics and metabolomics of V. songaricum populations (VSPs), collected from different geographical regions of Iran for further breeding and exploitation programs. Inter-simple sequence repeat (ISSR) analysis showed a significant difference among the twelve studied VSPs, which were classified into five main groups based on an unweighted pair-group method with arithmetic and principal coordinate analysis. Ninety-six bands were produced by fourteen ISSR primers, among which 92.7% of them were polymorphic at the species level. The essential oils were analyzed by means GC-FID and GC-MS and five main chemotypes, including docosane (I), methyl chavicol (II), methyl eugenol (III), beta-damascenone (IV), and alpha-bisabolol (V) were characterized. HPLC-PDA-MS was further used to detect and to measure the phenolic compounds and harpagoside content in methanolic extract of VSPs. The main compounds identified in the VSPs extracts were rutin, quercetin, rosmarinic acid, salicylic acid, ferulic acid, p-coumaric acid, 2, 5-dihydroxybenzoic acid, 3, 4-dihydroxybenzoic acid, and harpagoside. Cluster analysis based on phytochemical data divided VSPs into nine groups. Subsequently, data were analyzed by multiple regression analysis to identify the correlation between genetic and metabolic diversity. The phytochemical data as the dependent variable showed significant association with bands obtained from molecular data. The high variation observed in essential oils, phenolics, and harpagoside among the VSPs establish a good potential to select the best genotype in breeding projects.