Scientists have developed a new way of identifying whether a cannabis plant is rich in THC or not – without testing for THC levels.
Laws in many countries consider marijuana used for recreational or medical purposes different from industrial hemp. But when it comes down to genetics, marijuana and hemp aren’t much different at all.
Both marijuana and hemp plants belong to the Cannabis genus, and both contain enzymes that produce cannabinoids. The difference is only at the last step of the cannabinoid production process, where cannabigerol (CBG) is converted to either tetrahydrocannabinol (THC) or cannabidiol (CBD).
Hemp plants produce greater amounts of the CBDA synthase enzyme, which converts CBG to CBDA. Marijuana plants, on the other hand, produce greater amounts of THCA synthase, which converts CBG to THCA. CBDA and THCA are converted to CBD and THC upon heating.
Since hemp and marijuana plants are very similar in appearance, scientists have been trying to identify a genetic marker that would provide simple screening methods for discriminating the two.“The marker represents a valuable tool for the evaluation of Cannabis material”Now a team from Germany say they’ve succeeded in doing just that.
Published this week in the Journal of Forensic Science, the researchers showed that by using polymerase chain reaction (PCR) methods to screen for specific phenotypes within the THC synthase gene, they could identify Cannabis sativa plants as being either THC-rich or CBD-rich.
They confirmed the accuracy of the test by screening a batch of over 200 mixed-type plants.
Unfortunately, the test doesn’t provide a quantitative value of THC content. But other technologies like gas chromatography already allow for accurate analysis of THC content. The scientists believe their testing method could be used when THC analysis is not an option.
“Although a quantitative prediction of the THC content cannot be made, the marker represents a valuable tool for the evaluation of Cannabis material, for which a THC assessment is not possible,” wrote Dr. Christina Staginnus of the University of Frankfurt and her colleagues.
This, they explain, could include cases where the plants have yet to reach maturity. For example, when evaluating the purity of seed batches.
As well, the researchers say their test could be used on different parts of the plant, including those that don’t typically produce cannabinoids, such as the roots or badly damaged plant fragments.