Researchers from Université Laval in Quebec have mapped key genetic markers responsible for cannabinoid production in marijuana, a discovery they say could revolutionize strain development and genetic selection in the legal cannabis industry. The findings were published in Plant Genome.
Using a genome-wide association study (GWAS) on 174 marijuana strains from Canada’s legal market, the team analyzed over 282,000 single-nucleotide polymorphisms (SNPs) to identify 33 markers linked to the production of 11 cannabinoids, including THC, CBD, CBDA, THCV, and CBN. The study also pinpointed 18 candidate genes, some of which contain variants that alter protein function in ways that may affect how much THC or CBD a plant produces.
Among the most important discoveries was a massive haplotype—a block of genes that are inherited together—on chromosome 7. This haplotype was present in roughly 95% of THC-dominant (Type I) strains and is strongly associated with high THC content and the absence of CBD. The findings support a codominant inheritance model in which certain allele combinations determine whether a plant is THC-dominant, CBD-dominant, or produces a balanced mix.
Notably, the researchers found that different SNPs influenced both major and minor cannabinoids. Some markers explained more than 50% of the variation for cannabinoids like CBGA, CBC, and CBN, highlighting their potential value in breeding programs aimed at producing strains with custom cannabinoid profiles.
The study’s authors say these genetic markers could be used in marker-assisted selection (MAS), a modern breeding method that allows cultivators to screen for specific traits using DNA analysis instead of time-consuming phenotype testing. This could significantly lower costs while increasing the efficiency and precision of cannabis cultivation.
The study concludes by stating:
To address the shortage of genetic markers associated with cannabinoid traits, which are essential for Cannabis research and industrial applications, this study provided a comprehensive catalog of SNPs that have major impacts on cannabinoid biosynthesis. Additionally, a massive haplotype discriminating Type I accession was identified on chromosome 7. These molecular markers will constitute an essential tool in breeding programs that utilize MAS. They promise to accelerate the selection process for promising accessions, potential crossing parents, while significantly reducing costs associated with labor-intensive phenotype-based selection methods. This advancement not only enhances our understanding of Cannabis genetics but also streamlines the development of cultivars with desired cannabinoid profiles, thereby supporting the growing needs of medical, recreational, and industrial sectors.
