Metabolic and molecular basis of floral scent differentiation in single- versus double-flowered tuberose (Agave...

Tuberose (Agave amica), valued in floriculture and perfumery for its fragrance and essential oil, suffers from limited genetic diversity, restricting breeding for enhanced floral scent. This study aimed to elucidate the biochemical and molecular basis of fragrance variation by profiling volatile organic compounds (VOCs) and associated gene expression in 14 commercially cultivated single- and double-flowered tuberose cultivars. VOCs were identified and quantified using gas chromatography-mass spectrometry (GC-MS), followed by multivariate statistical analyses, including principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). Cluster analysis was performed to classify cultivars based on fragrance profiles. Gene expression analysis targeted biosynthetic genes associated with ester and monoterpene production. A total of 111 VOCs were detected, with esters dominating across all cultivars. Single-flowered types exhibited higher ester levels and absence of monoterpenes, while double-flowered types contained monoterpenes and olefins. Discriminatory metabolites such as isoeugenol, eugenol, benzoic acid methyl ester, benzyl alcohol, methyl anthranilate, α-terpineol and methylisoeugenol differentiated single from double cultivars. Gene expression patterns revealed higher activity of ester-related genes (PtBCMT2, PtIEMT) in single types and monoterpene-related genes (PtTPS1, PtHDS) in double types. This integrative analysis highlights distinct metabolic and molecular signatures underlying fragrance differences between tuberose floral types. The identified key metabolites and candidate genes represent valuable targets for breeding strategies aimed at developing cultivars with tailored fragrance traits, thereby supporting innovation in floriculture and perfumery industries.