Researchers have created the most comprehensive map to date of genetic variation among cannabis plants in China, identifying nearly 2.7 million genetic variants.
The peer-reviewed study, published today in BMC Plant Biology, analyzed 271 Cannabis sativa accessions collected from 29 populations across 12 provinces in China. Researchers included scientists from Shenyang Medical College, China’s Institute of Forensic Science and Kaitai-bio.
Using whole-genome resequencing, researchers compared the plants with a reference cannabis genome and identified 2,699,120 single nucleotide polymorphisms, commonly known as SNPs, along with 42,201 insertion-deletion variants. The researchers said the resulting dataset represents the largest genetic resource for Chinese cannabis produced to date.
The plants included wild, landrace and cultivated varieties. Researchers found that they could be divided into five major genetic groups, with genetic relationships generally corresponding closely with geographic origin.
To investigate the genetics underlying cannabinoid production, researchers measured THC and CBD concentrations in 90 plants representing 14 of the populations and conducted genome-wide association studies comparing cannabinoid levels with genetic differences.
The CBD analysis identified 1,176 potentially associated SNPs across 294 genes. Of those, 140 SNPs in 52 genes met the study’s stricter threshold for genome-wide statistical significance.
The most prominent CBD-associated signal appeared near the end of chromosome 1 and corresponded to CBDAS, the gene encoding cannabidiolic acid synthase, an enzyme central to the production of CBD. Researchers also observed strong selection signals around CBDAS regions on chromosomes 1, 2 and 3.
The researchers found a more complicated genetic picture for THC. They identified 323 potentially associated SNPs across 82 genes, including 35 SNPs in 17 genes that reached genome-wide significance. However, despite several strong genetic signals, the researchers said they could not confidently identify a definitive candidate gene responsible for the strongest THC association based on its functional annotation.
The findings could have practical implications for marijuana and hemp breeding. Genetic markers associated with cannabinoid production could eventually help breeders more efficiently select plants for desired CBD or THC profiles without relying solely on cultivation and chemical testing.
Researchers said the genetic map could also support the development of varieties with improved yield, quality and environmental resilience, while providing a foundation for further research into the genetic basis of important cannabis traits. The study was supported by several provincial and academic research programs in China, and the authors reported no competing interests.
