Chemometric Analysis of Cannabinoids: Chemotaxonomy and Domestication Syndrome

Cannabis is an interesting domesticated crop with a long history of cultivation and use. Strains have been selected through informal breeding programs with undisclosed parentage and criteria. The term "strain" refers to minor morphological differences and grower branding rather than distinct cultivated varieties. We hypothesized that strains sold by different licensed producers are chemotaxonomically indistinguishable and that the commercial practice of identifying strains by the ratio of total THC and CBD is insufficient to account for the reported human health outcomes. We used targeted metabolomics to analyze 11 known cannabinoids and an untargeted metabolomics approach to identify 21 unknown cannabinoids. Five clusters of chemotaxonomically indistinguishable strains were identified from the 33 commercial products. Only 3 of the clusters produce CBDA in significant quantities while the other 2 clusters redirect metabolic resources toward the THCA production pathways. Six unknown metabolites were unique to CBD-rich strains and/or correlated to CBDA and 3 unknowns were found only in THC-rich strains. Together, these data indicate the domestication of the cannabis germplasm has resulted in a loss of the CBDA pathway in some strains and reallocation of resources between CBDA and THCA pathways in others. The impact of domestication is a lack of chemical diversity and loss of biodiversity in modern cannabis strains.