Beyond Chemodiversity: A General Biosynthetic Diversity Index for Plant Metabolic Architecture in Ecology,...

Plant chemical diversity is commonly assessed using abundance-based metrics that treat metabolites as independent components, although these approaches do not explicitly represent how compounds are organized across biosynthetic routes. Here, we present a proof-of-concept application of the General Biosynthetic Diversity Index (GBDI), a pathway-informed descriptor of plant chemical mixtures that integrates relative metabolite abundance with biosynthetic-route attribution. The index was evaluated using hypothetical mixtures and essential oil datasets from Piper rivinoides Kunth (Piperaceae), including organ-level and ontogenetic comparisons. Limiting scenarios distinguished internally branched mono-pathway mixtures, balanced multi-pathway allocation, and ultra-dominated canalized profiles, supporting the use of GBDI as a descriptor of abundance-weighted biosynthetic architecture rather than pathway richness alone. In P. rivinoides, leaves showed the highest organ-level architectural diversity, branches showed focused monoterpene branching, and stems and roots showed more canalized arylpropanoid-rich architectures. Across ontogenetic stages, GBDI increased from juvenile to mature phases; however, this trend was interpreted descriptively because only five ordered phases were available. These findings position GBDI as a complementary metric for describing pathway-informed chemical organization and for generating testable ecological, evolutionary, and bioprospecting analyses.