Genetic and metabolite diversity of Sundaland Heptapleurum (Araliaceae) insight into evolutionary and specialized metabolite

BACKGROUND: The genus Heptapleurum Gaertn (previously treated as Schefflera J.R.Forst. & G.Forst.) within the Araliaceae family is recognized for its significant medicinal value and complex taxonomy. However, an integrated understanding of its evolutionary and metabolite diversity remains unexplored, especially in the Sundaland region (i.e., Java and Sumatra). Here, we integrate genomics and metabolomics to unravel the evolutionary relationships and metabolite diversity of 10 Heptapleurum species from Sundaland. RESULTS: We assembled 10 new complete plastid genomes (plastomes) and 45S nuclear ribosomal DNA (nrDNA) sequences, identifying significant variation and potential key molecular markers. Metabolomics identified 152 metabolites, mainly phenolics and terpenoids. Metabolite profiles of H. rhynchocarpum and H. capituliferum were more correlated with phylogeny than with geography; these two species were separate from the main Heptapleurum clade. Four species, H. farinosum, H. longifolium, H. rigidum, and H. fastigiatum, have almost identical plastomes and 45S nrDNA structures, suggesting they may represent closely related species with different phenotypes, as evidenced by distinctive metabolite compositions. CONCLUSIONS: Crucially, there is an incongruence between the genetic and chemical phylogenies, underscoring that while chemotaxonomy reflects functional diversity, genetic data remains the definitive standard for evolutionary inference, with the potential for reclassifying H. rhynchocarpum and H. capituliferum. This study provides a foundation for future taxonomic revisions, conservation, and drug discovery of Heptapleurum.