• A comparative analysis was performed among selected Mentha accessions using morphometric, phytochemical, and ISSR markers. • Intraspecific variation was observed in morphometric and biochemical traits of M. spicata . • MsKGP (Kharagpur) accession showed the highest trichome density and carvone concentration. • M. rotundifolia showed genetic distinction despite phenotypic similarity to M. spicata . • Menthol-rich M. arvensis formed a distinct branch across all levels of clustering. The genus Mentha (Lamiaceae), widely distributed across the globe, holds immense economic significance due to its distinct aroma and pharmaceutical applications. Extensive natural hybridization within the genus has led to complex taxonomic challenges for demarcating numerous species, subspecies, and varieties. Profound intra- and interspecific variations in the morpho-physiology and volatile profiles of these varieties are often shaped by geo-climatic factors such as altitude, temperature, and environmental stress. In this study, six Mentha accessions representing three different species ( M. spicata, M. arvensis , and M. rotundifolia ) collected from distinct geographical regions of India were comparatively characterized for morphological traits, glandular trichome distribution, and phytochemical profiles. Molecular marker-based differentiation using inter simple sequence repeat (ISSR) analysis was employed as a supportive tool to assess genetic relatedness among the accessions. The M. spicata (Ms) accessions exhibited significant intraspecific diversity among them, particularly in vegetative growth parameters, trichome architecture and phytochemical profiles, depicting high adaptive plasticity. Amongst them, MsKGP (Kharagpur) showed the highest trichome density (73.18 Nos./mm 2 ) and carvone concentration (5206.70 nmol/g fresh mass), while MsKL (Keylong) contained the highest rosmarinic acid levels (1151.64 µg/g fresh mass). M. arvensis (Ma) consistently formed a distinct cluster in morphometric, biochemical and ISSR-based groupings, primarily due to its high menthol content (8533.07 nmol/g fresh mass) and robust morphological traits, including broad stems and thick leaves, associated with enhanced structural resilience. In contrast, despite exhibiting genetic distinction in the ISSR-based dendrogram, M. rotundifolia (Mr) clustered with M. spicata (Ms) accessions in morphometric and biochemical groupings, indicating a pronounced interspecific convergence of phenotypic traits. Overall, this study provides a focused integrative characterization of selected Indian Mentha accessions, offering baseline insights into their morphological, trichome structural, and phytochemical attributes with potential relevance for future germplasm evaluation and resource utilization.
Chatterjee et al. (Thu,) studied this question.