Integrative geno-metabolomics of tenasserim turmeric (Curcuma candida (Wall.) Techapr. & Škorničk.) with insights into volatile biosynthesis across the turmeric genus

Tenasserim turmeric (<i>Curcuma candida</i>), an edible species native to the Tenasserim Range along the Thailand-Myanmar border, has been traditionally consumed as a vegetable. Although previous studies on this plant have been reported, the volatile profiling of <i>C. candida</i> rhizomes remains largely unexplored, particularly in comparison with other <i>Curcuma</i> species. This study aimed to characterise the volatile profiles of <i>C. candida</i> rhizomes from distinct natural populations, to authenticate its phylogenetic placement and clarify its relationships within the genus <i>Curcuma</i> and to integrate major compounds and their biosynthetic pathways with respect to a phylogenetic framework. Volatile profiling was conducted using static headspace solid-phase microextraction (SHS-SPME) coupled with gas chromatography time-of-flight mass spectrometry (GC-TOFMS) on samples collected from two populations in northern and western regions of Thailand. Multivariate statistical analyses revealed distinct profiles between the two populations, indicating a significant environmental influence on metabolite composition. (<i>E</i>)-β-Farnesene was the predominant volatile constituent, followed by humulene, furfural, longiverbenone and mustakone. In parallel, molecular phylogenetic reconstruction was conducted, which positioned <i>C. candida</i> in subgenus <i>Ecomatae</i>. The biosynthetic pathways of mono-, sesqui- and diterpenes were traced to reveal differences in the accumulation of major compounds in relation to genetic lineages. Comparative analysis of terpene profiles across subgenera provides valuable insights into the chemotaxonomic relationships within <i>Curcuma</i> and highlights potential evolutionary trends in their biosynthetic pathways. These findings advance our understanding of evolutionary chemical diversification of <i>C. candida</i> within <i>Curcuma</i> and highlight the potential of a geno-metabolomics approach to link phytochemical diversity with infrageneric relationships and environmental adaptation.