The first created genetic map of cannabis showed the possibility of its use in medicine.

It turned out that tetrahydrocannabinol (THC) and cannabidiol (CBD) - the biologically active substances that cannabis produces - arose because of the ancient colonization of the plant genome by viruses.

University of Toronto staff says that this find was only one of many discoveries that were made thanks to the long-awaited map of the cannabis genome, which describes in detail the location of genes on the chromosomes. Among other discoveries is the discovery of the gene responsible for the production of cannabichromene (CBC), a lesser-known cannabinoid that can also be used as cannabinol. The results are published in the journal Genome Research.

“The chromosome map will be the main basis for further research, which, despite the widespread use and widespread use of cannabis, has lagged behind the study of other cultures due to legal restrictions,” said study co-author Tim Hughes.

A new map shows how hemp and marijuana, which belong to the same Cannabis sativa species, develop as separate strains with different chemical properties. Cannabis plants grown for the manufacture of drugs (marijuana) are abundant with the psychoactive substance THC, while hemp produces cannabidiol or CBD, known for its medicinal potential. Some use CBD to relieve pain, and cannabidiol itself is being tested as a treatment for epilepsy, schizophrenia, and Alzheimer's.

Enzymes that produce THC and CBD are encoded by the THCA and CBDA synthase genes, respectively. They are found on the sixth chromosome of ten, into which the cannabis gene is “packed”. Enzymes are surrounded by vast areas of distorted DNA coming from viruses that colonized the gene millions of years ago. This viral DNA, or retrotransposons, created copies of itself that spread throughout the genome, moving into the DNA of the host cell.

Researchers believe that duplication of the gene for early synthases and the expansion of retrotransposons forced cannabis to be divided into chemically different types, the difference in which people later discovered, selecting those plants according to the principle of their effect - for example, according to the high level of THC.

The gene sequences for syntheses of THCA and CBDA are almost identical, which confirms the idea that they come from the same gene that was duplicated millions of years ago. Over time, one or both copies of the genes were scrambled by invading retrotransposons and, developing parallel to each other, began to produce two different enzymes - CBDA synthase, found in fiber-type hemp and THCA synthase in marijuana.

“Scientists still have their hands tied due to limitations in the study of this species, but legalization and the expected removal of the strict research regulations will provide opportunities for additional tests. And today Canada is leading in this matter, ”the researchers conclude.