Updated: Feb 9
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A September 2021 study entitled "Comparative Genetic Structure of Cannabis Sativa Including Federally Produced, Wild Collected, and Cultivated Samples" that was published in the journal Frontiers in Plant Science explored genetic characteristics of "cannabis supplied by the National Institute on Drug Abuse (NIDA) relative to common categories within the species." This was the first genetic study to include research grade marijuana from NIDA.
The study's authors noted that cannabis has been used by humans for thousands of years, "with evidence of cultivation dating back as far as 10,000 years." They noted how "drastic changes in patterns of cannabis use" have emerged in the United States as a result of the "widespread relaxation of laws that previously limited both medical and recreational consumption" and hemp cultivation. "This has led to a need for extensive research into the basic biology and taxonomy of cannabis," declared the researchers.
The study explored "several commonly described subcategories that are widely recognized" and identified two primary genetic groups for cannabis: Hemp and drug type Marijuana.
One Species & Two Genetic Groups
"Cannabis sativa is the only described species in the genus Cannabis (Cannabaceae)," reported the study, dispelling with the claims that cannabis is two or more species. The study explored "several commonly described subcategories that are widely recognized" and identified two primary genetic groups for cannabis:
Hemp: "Hemp or hemp type which is legally defined in the United States as Cannabis containing no more than 0.3 percent [delta-9] THC."
Marijuana: "Marijuana, drug type, or drug type which encompasses all Cannabis with THC concentrations >0.3 percent THC."
Interestingly, the study noted that the term marijuana "is controversial, so unless referencing 'research grade marijuana' as defined by the U.S. government, we utilize the term 'drug type,' as there is no acceptable widely used term for Cannabis that does not classify as hemp."
The study noted that hemp types of Cannabis "tend to have higher concentrations of CBD than drug types" and that high THC drug types typically feature more than 12 percent delta-9 THC and "average 10–23 percent THC in dispensaries."
The study analyzed 49 samples of cannabis from the United States, including "Wild (feral) hemp, Cultivated hemp, NIDA samples, high CBD drug type, and high THC drug type."
"In the current study, we investigated the genetic relationship of two types of NIDA-obtained Cannabis to commercially available drug-type Cannabis, as well as wild (feral) and cultivated hemp," reported the scientists. They said that, "because Cannabis has been under heavy artificial selection for different traits such as THC content or industrial uses," they focused exclusively on genetic data.
"There is continuing debate among experts surrounding the appropriate taxonomic treatment of Cannabis groups, which is confounded by colloquial usage of the terms sativa, indica, and hybrid."
Sativa & Indica
Regarding the popular cannabis product naming convention involving sativa, indica, and hybrid, the study noted that "there is continuing debate among experts surrounding the appropriate taxonomic treatment of Cannabis groups, which is confounded by colloquial usage of these terms versus what researchers suggest is more appropriate nomenclature."
Using genetic analysis, the study was not able to identify "clear and consistent differentiation among the three commonly described high THC drug strain categories," even though "both the recreational and medical Cannabis communities maintain that there are distinct differences in effects between Sativa and Indica strains."
"Our results clearly demonstrate that NIDA Cannabis samples are substantially genetically different from most commercially available drug-type strains," reported the study's authors. They noted that the NIDA samples "share a genetic affinity with hemp samples in several of the analyses," but noted that they are not claiming that NIDA has been supplying hemp for Cannabis research.
"We are confident that our analyses show that the 'research grade marijuana' supplied by NIDA is genetically different from the retail drug-type samples analyzed in this study."
"Rather, we are confident that our analyses show that the 'research grade marijuana' supplied by NIDA is genetically different from the retail drug-type samples analyzed in this study," reported the research.
The paper reported that its data and "previous chemotypic investigations" have concluded that NIDA is supplying cannabis samples that "do not align with what is available for consumers." The study's authors stated: "Our hope is that the NIH and NIDA will support the cultivation of Cannabis that is representative of what medical and recreational consumers are using" and that medical practitioners, researchers, and patients "deserve access to Cannabis products that are comparable to [those] available on the legal market."
The study stated that its results "contribute to the growing consensus that hemp- and drug-type Cannabis can be consistently differentiated, but all Cannabis groups are currently considered a single species that has been [selectively bred] for different uses."
The research noted that "most Cannabis strains are a product of clandestine breeding in underground markets," resulting in the fact that their "presumed lineage may not match their actual genetic group."
"Although the categories Sativa, Indica, and Hybrid are frequently used in the Cannabis industry and among consumers, researchers have yet to find consistent phenotypic and/or genotypic traits driving these widely referenced categories," reported the study. The scientists attributed this to "the high degree of intentional hybridization among drug-type Cannabis."
Increasing interest in cannabis "with alternative combinations of cannabinoids other than THC" has led to increased breeding between hemp and drug types of the plant species, "further diluting any historical genetic distinctions that might have existed."
The study observed that increasing interest in cannabis "with alternative combinations of cannabinoids other than THC" has led to increased breeding between hemp and drug types of the plant species, "further diluting any historical genetic distinctions that might have existed."
It reported that the high CBD drug-type samples were "genetically more divergent from the hemp group than the high THC drug-type groups," suggesting that they may be hybrids of hemp-type and high THC drug-type Cannabis.
The study concluded that its data "indicates the need for additional research and refinement of our understanding of Cannabis genetic structure and how those differences might impact Cannabis consumers."
Due to the dynamic landscape of cannabis regulation and availability, the researchers noted that "it is not surprising that commercially available Cannabis contains a diversity of genetic types." It noted how commercial cannabis "has come to market through non-traditional means, leading to many inconsistencies."
"Research conducted with NIDA Cannabis may not be indicative of the effects that consumers are experiencing" from commercial cannabis in legal markets based on the genetic divergence found between the two types by this study."
The study's authors stressed the "substantial genetic divergence" among individual cultivars (strains) and stated that this "only exacerbates questions about the impacts of Cannabis consumption." They said their results emphasize the need to increase consistency of product within legal cannabis markets and that "research grade marijuana" should "accurately represent what is accessible to consumers."
The research wrapped by concluding that "research conducted with NIDA Cannabis may not be indicative of the effects that consumers are experiencing" from commercial cannabis in legal markets based on the genetic divergence found between the two types by this study.
"Additionally, research has demonstrated that Cannabis distributed by NIDA has lower levels of the principal medicinal cannabinoids (THC and CBD) and higher levels of the THC degradation product cannabinol (CBN)." The scientists reported that their results "demonstrate the need for there to be a greater diversity of Cannabis available for medical research."
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