Identification of high carnosic acid rosemary (Salvia rosmarinus Spenn.) genotypes through genetic diversity exploitation, chemical profiling, and transcriptomic approaches

Salvia rosmarinus Spenn. is an aromatic/pharmaceutical plant belonging to the Lamiaceae family and is well-known for its pharmacological, culinary, and cosmetic properties, which seem to be associated with carnosic acid (CA)/carnosol (CO), content. Due to the high demand for S. rosmarinus genotypes rich in CA/CO, a multidisciplinary approach consisting of genetic, chemical and transcriptomic methodologies was utilized to evaluate 57 S. rosmarinus genotypes for high CA/CO content. These genotypes were analyzed for CA/CO contents, antioxidant activity, and genetic diversity from which 61% was detected within populations rather than among populations (39%). Transcriptomic analysis of two genotypes, G1 and A7 poor and rich in CA content, respectively, revealed a significant differential expression of genes involved in the CA biosynthetic pathway that was further confirmed by qRT-PCR, suggesting that ferruginol synthase (FS1) and carnosic acid synthase (CAS) can serve as potential molecular markers for high CA content in S. rosmarinus future breeding. The functional analysis of single nucleotide polymorphisms (SNPs) and insertions/deletions (InDels) within the coding regions of these genotypes revealed significant variants with high and moderate impact, potentially contributing to the increased CA accumulation in the A7 genotype.