Chemotypic and genetic characterization of two rosemary (Rosmarinus officinalis L.) cultivars

Rosemary (Rosmarinus officinalis L.) is a widely used herb known for its essential oils with various applications. This study aims to assess the chemical composition and genetic diversity of two rosemary cultivars: Balady (grown in Egypt) and French (grown in Saudi Arabia). Two rosemary cultivars, Balady and French, were used for analysis. Gas chromatography–mass spectrometry (GC–MS) was employed to identify and quantify the chemical compounds present in the essential oils of both cultivars. DNA-based markers, standard codon target polymorphism (SCoT) and inter-simple sequence repeats (ISSR), were used to assess the genetic diversity between the cultivars. Significant variations were observed in the chemical composition of the essential oils. Balady oil contained 126 compounds compared to 77 in French oil. Six of the top 15 most abundant compounds were common to both cultivars. Camphor was the most abundant compound in Balady oil (12.86%) followed by Eucalyptol, Verbenone, Isoborneol, Bornyl acetate, and Linalool. The French cultivar exhibited a different profile with Eucalyptol being the most abundant, followed by 3-Octen-5-yne (unique to French cultivar) and Verbenone. Balady oil displayed a higher percentage of oxygenated monoterpenes (> 60%) compared to French oil (~ 50%). The hydrocarbon monoterpene content was higher in French oil compared to Balady oil. Balady oil exhibited a significantly higher content of sesquiterpenes (26.92%) compared to French oil (2.07%). SCoT and ISSR markers generated 27 and 16 bands, respectively, with a high average polymorphism rate (29.6% and 31.3%). The study revealed significant variations in the chemical composition and genetic makeup of Balady and French rosemary cultivars. These findings highlight the influence of geographical origin on the essential oil profile. Additionally, the high level of polymorphism detected with DNA markers suggests their potential use for identification and breeding programs in R. officinalis L.