Thanks to the Marihuana Tax Act of 1937 and the Controlled Substances Act of 1970, weed has remained a federally illegal substance in the United States for over 80 years. Opponents of cannabis often claim that a lack of research is one of their main reasons for being against weed. However, the prohibited status of marijuana is one of the primary reasons for the lack of research!
It has often been said that legalization would facilitate an improvement in our understanding of marijuana. While the herb is still illegal federally in America, the same cannot be said for our neighbors, Canada, where cannabis was legalized in October 2018.
It is there that researchers have created the world’s first Chromosome Map, which reveals the evolutionary past of the marijuana plant, along with insights into how it could be used in medicine in the future. The study, sourced from the University of Toronto, was published in the Genome Research journal in November 2018.
It is a fascinating document, but one of the most surprising findings revolved around the origins of the most abundant cannabinoids in the marijuana plant, THC and CBD.
You’re Getting High Because of Ancient Viruses!
The study is the product of seven years’ worth of research. It began with Harm van Bakel, Jonathan Page, and Tim Hughes, who collaborated in 2011 and released their first draft of the cannabis genome. At the time, it was too fragmented to provide us with enough telling information.
This all changed, and by the end of 2018, the team was ready to stun the world with its remarkable findings. Humans have been using weed for thousands of years, and we have always assumed that the marijuana plant contained its existing compounds. Not so, according to the Chromosome Map.
The Map is the first time that anyone has ever published a complete map of the cannabis genome. The study found that ancient viruses might have colonized the marijuana plant’s genome and accelerated its evolutionary process, resulting in the creation of THC and CBD.
The Map reveals how marijuana and hemp, which both belong to the Cannabis sativa species, evolved as different strains with unique chemical properties. As you probably know by now, the weed we find on the market today contains a significant amount of THC, a cannabinoid that induces a psychoactive high. Hemp, on the other hand, contains a preponderance of CBD, a non-intoxicating compound said to have medicinal value.
It so happens that the enzymes that make CBD and THC are encoded by CBDA and THCA synthase genes, respectively. You will find both on chromosome 6 of the 10 chromosomes the cannabis genome is packaged in. It is here that the enzyme’s genes are engulfed by DNA which came from viruses that colonized the cannabis genome several million years ago. The viral DNA created copies of itself which spread across the genome via other sites in the DNA of the host cell.
According to Van Bakel, there are millions of retroelements (a term used to describe the viral DNA) in plant genomes. As a result, linking the genes on chromosomes is akin to completing a gigantic puzzle where 75% of the pieces are almost the same color. By combining PacBio sequencing technology with the genetic map, the research team was able to increase the number of puzzle pieces and find enough distinct features to expedite the process of assembly and find the synthase genes.
The team believes that expanding retroelements and gene duplication of the synthase gene resulted in the split of marijuana into chemically different types. Humans played their own role. We selected plants that contained what we termed ‘desirable’ chemical traits, such as high THC.
The gene sequences for the CBDA and THCA synthases are almost identical, which gives credence to the notion that they came from the same gene, duplicated several million years ago. When retroelements invaded one or both copies of the gene, the gene(s) became scrambled and evolved separately. Ultimately, they produced a pair of very different enzymes: THCA in marijuana, and CBDA in hemp.
Scientists have been confused for decades because the enzymes have enormous similarities at the DNA level. Also, most strains contain both THC and CBD even though hemp breeders do their best to ensure their crops doesn’t contain any THC. One major consequence of the Chromosome Map is that we now know there are two different genes in action. This means breeders should be able to separate them and grow THC-free plants.
THC and CBD: There’s Still a LOT to Learn
We’re still not sure what cannabis would have been like had it not been for the ancient viruses. When you bear in mind that weed’s closest relatives are plants such as hops and mulberry, it is likely that the plant wouldn’t get you stoned, which would be a terrible shame!
Marijuana research has come a long way in recent times. Remember, the draft cannabis genome of 2011 wasn’t detailed enough to provide a sufficient outline of where genes on the chromosome were positioned. In February 2018, Hughes and his team unveiled the map at a conference without a paper but promised that the subsequent documentation would be shared publicly by the end of the year, and it was released on time.
It is clear that the Chromosome Map, and research like it, are crucial elements of getting to know more about the marijuana plant. The team also identified the gene responsible for producing CBC. It is a lesser-known cannabinoid but then again, outside of the big two, they all are! There are over 100 cannabinoids in marijuana, and we are only now beginning to scratch the surface in research terms.
CBC is believed to have anti-inflammatory effects and could play a role in the much-hyped ‘entourage effect,’ which suggests that cannabinoids and terpenes work better together. Now that we’ve found the gene responsible for CBD synthesis, it will be possible for breeders to tailor the amount of the cannabinoid found in plants they grow in future.
In many ways, it is scary that so many people consume marijuana, hemp, THC, and CBD, without fully understanding their effects on the human body and mind. According to Hughes, one of the most crucial things we have yet to learn is what use CBD and THC have for the plant itself. We are of course assuming that these compounds were around long before man. Hughes stated that the fact the compounds have such an effect on people is fortunate.
What Does Having a Genetic Map Mean?
Calling it a huge discovery is actually selling it short. A genetic map is the starting point for the high-quality breeding of any plant, not just marijuana. There are various reasons why it took so long to find this map. First of all, legislation has barred scientists from studying and experimenting with the plant.
Also, the bigger the genome, the harder it is to categorize. It so happens that the cannabis genome is pretty large! The viral elements made it tough to sequence and assemble the genome. Finally, however, we have access to this crucial piece of knowledge.
According to Todd Michael of the J. Craig Venter Institute in California, having a fully mapped cannabis genome is “revolutionary” for the industry. From now on, experts will find it easier to pinpoint the traits needed for faster and easier to grow strains. Therefore, marijuana will grow faster and better.
Then there is the small matter of being able to fine tune a strain’s ability to produce CBC, THC, and CBD. Eventually, we’ll be able to do the same with the rest of the plant’s cannabinoids. Imagine a situation where you could modify the terpene content of weed to control the high you receive.
Final Thoughts on This Scientific Breakthrough for THC and CBD
Jonathan Page summed up the problem with marijuana research neatly. According to Page, “Mainstream science has still not done enough because of research restrictions.” Fortunately, legalization of the herb, along with relaxing the regulation on research, means scientists can finally study the plant closely. This breakthrough shows that Canada is set to become a world leader in marijuana research and join nations such as Israel in this field.
Unfortunately, the United States will continue to be left behind as long as the ridiculous restrictions on research are allowed to continue. In the U.S., if you want to research a Schedule I drug, such as cannabis, you have to get a license from the DEA to show that you are certified to work with these substances.
Studies must receive approval from three federal agencies before finally moving to a clinical trial. To make things worse, researchers can only source their weed from the University of Mississippi and NIDA. The weed given to research teams is of a very low standard and nothing like the weed you’ll get in a dispensary.
It is a long and convoluted process that will only improve once marijuana is federally legalized, one feels. Until that day comes, American cannabis scientists will continue to be stymied in their research.