Volatile diversity in wild populations of rosemary (Rosmarinus officinalis L.) from the Tyrrhenian Sea vicinity cultivated under homogeneous environmental conditions

Abstract

Rosemary (Rosmarinus officinalis L.) is an evergreen plant, a member of the Lamiaceae family. It is distributed throughout the Mediterranean, where it is used primarily as a spice herb for culinary purposes. In the present study 18 wild populations of rosemary distributed throughout the Tyrrenian Sea and its vicinity were tested for chemical profile. The populations were initially cultivated for 2 years under homogenous environmental conditions to minimize the potential effect of geographic surroundings on volatile composition (phenotype) that masked the true genotypic differences. A total of 58 compounds, representing 95.5–98.7% of the volatiles were detected. Volatile compounds were grouped into 27 oxygenated monoterpenes, 18 sesquiterpenes hydrocarbons, 10 monoterpene hydrocarbons, 1 oxygenated sesquiterpene, and 2 miscellaneous compounds. Sesquiterpenes and oxygenated terpenes were the main constituents in the rosemary oil. PCA and UPGMA dendrogram identified three chemotypes designated ‘chemotype A’ dominated by 1,8-cineole and β-pinene; ‘chemotype B’ dominated by α-pinene and verbenone and ‘chemotype C’, dominated by camphor and myrcene. The variability of volatiles in the 18 populations was moderately correlated (0.48≤r≤0.75) to geographic coordinates (latitude and longitude), suggesting that once environmental effects are removed genetics and origin are the key factors in chemotype variation in rosemary.