Despite cannabis’s growing use in the US and the variety of cannabis products available, there is no objective standard for classifying those products. Indica and sativa, the most common categorizing labels, are supposedly rooted in two different plant types, but these indica and sativa labels are widely debated. A growing body of evidence shows that the descriptions on cannabis products are misleading and inconsistent between growers, an especially concerning problem for medical use, cannabis industry experts say.
A new study used chemical and genetic analysis to show that, while products labeled 'indica' or 'sativa' are genetically indistinct, markers in genes that control the expression of key psychoactive and aroma compounds vary significantly across products and could be used to classify cannabis.
Terpenes and cannabinoids are key classes of compounds present in cannabis and are responsible for both aromas and psychoactive effects. A previous study used gas chromatography/mass spectrometry to quantify levels of 40 terpenes and cannabinoids in almost 300 cannabis samples from a distributor in the Netherlands.
Building on that, a team of researchers led by agricultural geneticist Sean Myles at Dalhousie University extracted high-quality DNA from 137 of the samples. The team identified 116,296 sites of genetic variation within the genomes and analyzed them for statistical links with the terpene profiles. The researchers evaluated how accurately those data matched a five-point labeling scale, ranging from 100% indica to 100% sativa, that was provided by the samples’ distributor. Through this research, "the team identified the genetic markers for the genes that control the expression of those terpenoids, which could enable for cannabis the same highly selective breeding that’s already in use in other agricultural crops," Myles says.
Read more about the research at cen.acs.org.