Assessment of Genetic Diversity and Population Structure in Oil-Bearing Rose Genotypes Using Start Codon-Targeted...

The oil-bearing rose (Rosa damascena Mill.), traditionally cultivated in Bulgaria for centuries, and the rose oil produced from it are of major cultural and economic importance. Its distinctive fragrance and rich aromatic profile are highly valued worldwide. In this study, a set of 15 start codon-targeted (SCoT) molecular markers was used to evaluate the genetic diversity and relationships of 38 rose accessions. The analyzed materials included Bulgarian-bred R. damascena cultivars, a locally improved population ('Population 5'), three oil-bearing species (Rosa alba L., Rosa gallica L., and Rosa centifolia L.), Romanian heritage roses, and an unidentified rose genotype from an old Bulgarian plantation (Rosa sp.). The SCoT primers yielded a cumulative count of 238 bands, with an average of 12.9 bands per primer. The range of diversity markers, such as PIC (0.20-0.78), number of different alleles (1.5-2.00), Shannon's information index (0.24-0.69), and gene diversity (0.15-0.50), provided evidence of genetic differences among the examined accessions. Analysis of Molecular Variance (AMOVA) revealed higher genetic variation within groups (61%) than among the groups (39%). Multivariate analyses (UPGMA, PCoA, and STRUCTURE) resolved the accessions into major genetic clusters corresponding to their taxonomic identity or breeding history. The unidentified Rosa sp. formed a distinct genetic group, showing closer affinity to R. gallica. The locally improved R. damascena 'Population 5' exhibited higher genetic diversity than the Bulgarian cultivars. Overall, our results demonstrate the effectiveness of SCoT markers and the value of local and traditional rose germplasm as reservoirs of genetic diversity. The study provides a molecular framework to support breeding, conservation, and sustainable management of oil-bearing rose genetic resources.