Welcome to Higher Learning LV's Study Summary series. This series reviews and summarizes peer-reviewed research studies and was developed specifically for cannabis industry professionals. These study summaries provide easily digested quick reads for a variety of important issues regarding the commerce and chemistry of legal cannabis.
A 2019 study entitled "Terpenes in Cannabis Sativa—From Plant Genome to Humans" that was published in the journal Plant Science explored the lifecycle, commonality and diversity, and genetic characteristics of a wide range of terpenes produced by cannabis and tens of thousands of other plant species in nature.
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A Brief History
Like many comprehensive studies, the report provided some history about the use of cannabis by humans. "Cannabis is thought to have originated from central Asia and has been domesticated for over 5000 years.
The study explained how cannabis varieties that are low in psychoactive cannabinoids (such as delta-8 and delta-9 THC) are used for the production of fiber and oilseed. "However, the most valuable cannabis product today is the terpene- and cannabinoid-rich resin with its various psychoactive and medicinal properties," reported the study.
The researchers noted the number of terpenes found in different samples of cannabis, which ranged from a low of 12 to a high of 66, with an average of 31 terpenes detected in each sample.
The research noted that more than 150 terpenes and 100 cannabinoids "have been identified in the resin of different cannabis types. The resin is produced and accumulates in [the nearly microscopic] glandular trichomes that densely cover the surfaces of female flowers [during the final stages of growth].
Glandular trichomes that produce terpenes
The researchers noted the number of terpenes found in different samples of cannabis, which ranged from a low of 12 to a high of 66, with an average of 31 terpenes detected in each sample.
What's In A Name?
The study's authors suggested that many of the efforts to classify and name different chemotypes of the cannabis plant (something called chemotaxonomy) based on a variety of attributes, including terpene profile, have been mostly ineffective.
The researchers noted that the terpenes myrcene, beta-caryophyllene (BCP), and humulene (alpha-humulene) "appear to be present in most cannabis 'strains.'"
"The complexity of terpene biosynthetic systems, and the many different sources of terpene variation, renders these efforts often futile; in general, concepts of chemotaxonomy have been outdated by genetic science and chemotypes cannot reliably substitute for properly genotyped plants," reported the study.
Terpene Diversity in Cannabis
The researchers noted that the terpenes myrcene, beta-caryophyllene (BCP), and humulene (alpha-humulene) "appear to be present in most cannabis 'strains.'" Also noted as common were alpha-pinene, bisabolol, limonene, and linalool.
The study reported that much is being learned about the genetics of the plant and its influence, when combined with a variety of environmental and cultivation factors, on terpene production. It noted that "some terpenes, such as humulene and β-caryophyllene, typically co-occur in different cannabis samples."
The scientists explained how terpenes are especially delicate molecules that are best described as volatile. As such, a variety of environmental conditions, many of them common to the distribution and warehousing of cannabis and cannabis products, may result in a transformation where terpenes morph from one type to another or degrade entirely.
"Some terpenes, such as humulene and β-caryophyllene, typically co-occur in different cannabis samples."
"Other terpene derivatives detected in cannabis may arise non-enzymatically due to oxidation, thermal [changes], or UV [light]-induced rearrangements during processing or storage," noted the study. "These non-enzymatic modifications may add a level of variation that is independent of the plant genome and biochemistry," it continued.
The study noted the relative diversity of terpenes produced by marijuana. "Cannabis is a useful system for terpene research as it produces a large volume of a diverse terpene-rich resin on its trichome-covered surfaces," it reported.
The study also noted that, despite the fact that more than 150 terpenes have been identified in samples of cannabis, the biosynthetic mechanisms underlying the production (synthesis) of these terpenes has been documented for only 30 of them.
View the original study.
