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Integrated Classification of Cannabis Strains Marketed in Canada for Medical Purposes Based on Genetic, Chemical Profiles, and Morphological Traits

  • Author / Creator
    Jin, Dan
  • The vernacular naming convention commonly used by the cannabis community (“Sativa” and “Indica”) is inadequate for identifying or selecting strains for clinical research and medicinal production because they are arbitrary and inconsistent. In addition, they mostly contain tetrahydrocannabinol (THC) dominant strains while cannabidiol (CBD) dominant and intermediate strains (THC ≈ CBD), which are getting increased attention due to CBD’s use as a therapeutic, have not been systematically studied nor compared to THC strains. This study series proposed a new, reliable, and scientific classification system for medicinal purposes based on genetics, chemical fingerprinting, and morphological traits of 23 strains grown in a common garden experiment. Leveraging the recent release of the 10-chromosome cannabis genome map, this study sequenced the whole genome of 23 cannabis strains and identified 137,858 genome-wide SNPs that provided insight into the distribution of genetic diversity and population structure in modern cannabis sold in Canada. This study identified 344 multiallelic SNPs that were able to separate CBD dominant, intermediate, and THC dominant strains using discriminant analysis of principal components (DAPC). Using canonical correlation analysis, this study tested the goodness of fit between this genotypic clustering (aligned with chemotypes) and the chemotypic variation by quantifying secondary metabolites in various plant parts of the same set of strains. Canonical correlation analysis assigned individual plants into their chemotypes with 100% accuracy. Other than THC and CBD, minor cannabinoids, terpenoids, and flavonoids showed differentiation power between CBD dominant, intermediate, and THC dominant chemotypes. In phenotyping, this study tested the goodness of fit between the genotypic clustering (aligned with chemotypes) and the morphological variation using 30 traits measured during the vegetative stage, at the end of flowering, and on harvested flowers of the same set of strains. Canonical correlation analysis assigned individual plants to their preassigned genotypes with 92.9% accuracy. Both qualitative and quantitative traits showed differentiation power between CBD dominant, intermediate, and THC dominant chemotypes. In summary, this integrated investigation of Canadian cannabis strains showed that CBD dominant, intermediate, THC dominant strains can be separated at whole genome level and that the separation is further supported by chemotypic and phenotypic variation. This study series developed a set of classification rules for sorting strains into groups using identified traits or markers, individually or in tandem, that will facilitate strain identification and selection for research and clinical studies.

  • Subjects / Keywords
  • Graduation date
    Fall 2021
  • Type of Item
    Thesis
  • Degree
    Doctor of Philosophy
  • DOI
    https://doi.org/10.7939/r3-p7ff-ef05
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.