The genus Mentha is highly valued in pharmaceutical, culinary, and personal care industries due to its rich aromatic and pharmacological traits. However, its complex taxonomy and genetic diversity create challenges for breeding programs focused on aroma and therapeutic qualities. To address these challenges, this study developed and validated a rapid, semi-quantitative metabotyping method to efficiently profile volatile organic compounds (VOCs) in fresh Mentha leaves for pre-selection screening in breeding and cultivar development. Using headspace solid-phase microextraction coupled with gas chromatography–flame ionization detection (HS-SPME-GC-FID), 234 Mentha accessions from seven species and twelve hybrids were analyzed, identifying 36 VOCs. Of these, 29 detected across all species with highest quantitative abundance were selected for multivariate analyses (clustering, PCA, correlation). Cluster analysis grouped accessions into eight chemotypic clusters, and PCA explained 70% of variation along menthol-, carvone-, and linalool-type axes. Flow cytometry-based genome size analysis (2 C DNA content) was performed on 104 accessions to investigate polyploidy-related variation. Spearman rank correlation revealed statistically significant associations between genome size and specific oxygenated monoterpenes (particularly menthol: ρ = 0.561, P < 0.001), suggesting that polyploidy-driven genome size variation influences monoterpene biosynthesis pathways — with direct implications for breeding polyploid cultivars with enhanced essential oil yield and aroma intensity. Some hybrids displayed unique VOC profiles, including M. × suavis and M. × smithiana . Notably, this is the first VOC profiling report for M. × suavis and M. × villosonervata , expanding knowledge of less-studied hybrids and providing genetic resources for specialized aromatic applications. Species-level PCA validated that accession-level chemotypic variation fundamentally reflects species-level metabolic differentiation, confirming the robustness of clustering results. This rapid VOC-based metabotyping approach, complemented by genome size characterization, provides breeders with an efficient pre-selection tool for early-stage germplasm screening, accelerating development of superior cultivars for industrial and therapeutic applications. • HS-SPME-GC-FID enables rapid VOC profiling of fresh Mentha leaves for germplasm pre-selection without hydrodistillation. • Chemotypic analysis of 234 mint accessions identified 8 clusters across species and hybrids, highlighting key VOC diversity. • First VOC profiling of M . × suavis and M . × villosonervata reveals new chemotypes with linalool and carene profiles. • Genome size correlates with VOCs, especially menthol (ρ=0.561), linking polyploidy to monoterpene biosynthesis and aroma. • Integrating genome size and VOC profiling enables rapid mint selection; PCA confirms species-level metabolic differentiation.
Moradi et al. (Fri,) studied this question.