Study of the genetic and phenotypic variation among wild and cultivated clary sages provides interesting avenues for breeding programs of a perfume, medicinal and aromatic plant

A road-map of the genetic and phenotypic diversities in both crops and
their wild-related species can help identifying valuable genetic resources
for further crop breeding. The clary sage (Salvia sclarea L.), a perfume,
medicinal and aromatic plant, is used for sclareol production and
ornamental purposes. Despite its wide use in the field of cosmetics, the
phenotypic and genetic diversity of wild and cultivated clary sage remains
to be explored. We characterized the genetic and phenotypic variation of a
collection of six wild S. sclarea populations from Croatia, sampled along
an altitudinal gradient, and of populations of three S. sclarea cultivars.
We showed low level of genetic diversity for the two S. sclarea
traditional cultivars used for essential oil production and for ornamental
purposes, respectively. In contrast, a recent cultivar resulting from new
breeding methods, which involve hybridizations among several genotypes
rather than traditional recurrent selection and self-crosses over time,
showed high genetic diversity. We also observed a marked phenotypic
differentiation for the ornamental clary sage compared with other
cultivated and wild clary sages. Instead, the two cultivars used for
essential oil production, a traditional and a recent, respectively, were
not phenotypically differentiated from the wild Croatian populations. Our
results also featured some wild populations with high sclareol content and
early-flowering phenotypes as good candidates for future breeding
programs. This study opens up perspectives for basic research aiming at
understanding the impact of breeding methods on clary sage evolution, and
highlights interesting avenues for clary breeding programs.