Morphological, genetic and essential oil variation of Greek sage (Salvia fruticosa Mill.) populations from Greece

Greek sage (Salvia fruticosa Mill.) is an aromatic-medicinal plant, indigenous to Greece, rich in bioactive ingredients, henceforth in demand by the food, pharmaceutical and agricultural industries. Its use is hampered by the fact that Greek sage cultivars are not available at the moment which is a prerequisite for a sustainable crop production. Development of cultivars requires knowledge of the material's phenotypic range of expression, of the existing genetic diversity, and of the effects of the environment on the phenotypic expression. For this purpose, essential oil (EO) and morphological traits were measured in a hundred individual plant samples of ten populations, from different locations of the Peloponnese (Greece). Significant differences among populations, both in yield and composition of EO, as well as in the morphological traits were observed. In fact, the EO components could assign most of the samples to their respective population (80-100%). The EO yield and main components were consistent, in one of the populations within a three year period of sampling, showing predominance of genetic background. Morphological traits showed a wide range of variation related to altitude, latitude and microclimatic conditions of the collection site, but were not correlated to the EO profile. For the genetic analysis and assessment of the diversity of the populations nine microsatellite markers were used. STRUCTURE analysis revealed the formation of four genetic groups, while PCoA managed to separate all populations according to their location of origin. Correlation was found between the EO composition and genetic diversity by the Mantel test. The present results demonstrate the high variability of the morphological and EO traits, and the high genetic diversity of the Greek sage populations growing in the Peloponnese. This diversity serves as the background for the selection of genotypes towards the development of S. fruticosa cultivars with high EO yield, superior EO composition and desirable agronomic traits.