• Dr. Anna Schwabe

What's up with the "research grade marijuana" from the University of Mississippi?

Updated: Nov 26, 2021

It's just not the same. No smell, leaves and stems, and certainly not 10% THC as the labeling would suggest.

Currently in the United States, the sole licensed facility to cultivate Cannabis sativa L. for research purposes is the University of Mississippi, which is funded by the National Institute on Drug Abuse (NIDA) which is under the umbrella of the National Institute of Health (NIH). Studies researching Cannabis flower consumption rely on NIDA-supplied “research grade marijuana.”

Researchers have questioned the quality of the material supplied by NIDA Dr. Sue Sisley was especially concerned when she was sent a box of what appeared to be leaves and sticks with no discernible flower material and lacked the distinct smell that we all know and love. When she tested the material, she found presence of mold and the potency was much lower than expected. This material was supposed to be used in her trials investigating therapeutic affects of Cannabis on PTSD patients. Of course this was unacceptable, but the suppliers at University of Mississippi maintained the mold must have been due to inadequate storage after they had shipped the material, which may have been the case if the additional absence of smell, lack of THC, and clear processing of entire plant parts (not just flower) suggested otherwise.

Following this finding, Dr. Daniela Vergara and her team at the University of Colorado set out to investigate how the "research grade marijuana” supplied by NIDA and grown at U of M measured up to flower available on the legal retail cannabis market. They found that reported THC potency of flower supplied for research was only 27% of flower on the market in four US cities. Not only that, but they found a significant amount of CBN (a degradation product of THC) indicating the flower being supplied to researchers was potentially stored incorrectly and/or was not fresh flower. Sisley announced and Vergara published their concerns in 2017, and while working on my research from 2017-2020, I searched records and interviews from U of M and the last reported harvest date I could find was 2014. That means that it is possible that flower for research has not been cultivated for years- however, it may just be that that information is not publicly available. I was curious of the genetic identity of the plants that were grown for research purposes in the US. Through some very convenient circumstances, I was able to acquire DNA from the plants grown at U of M. I had an undergraduate student that I was mentoring Connor, who was double majoring in chemistry and biology and was eager to get some genetic work in Cannabis under his belt. I designed a senior project for him investigating the "genetic spectrum" of the frequently referenced groups (or categories) in Cannabis sativa. Conner was tasked with extracting DNA, running the PCR amplification for the genetic markers I had designed for a previous investigation, conduct the data collection, and assist in some of the analytical tests and interpretation. I decided it would be interesting to throw in the two NIDA samples we had for fun just to see where they ended up comparatively.

We included 49 samples an assigned them to Wild Hemp (feral; 6) and Cultivated Hemp (3), NIDA (2), CBD drug type (3), and high THC drug type subdivided into Sativa (11), Hybrid (14), and Indica (10). We also had one sample of Cannabis ruderalis, a low THC, high CBD type possibly native to Central/Eastern Europe and Russia, which we included with the cultivated hemp group. These groups are somewhat arbitrary, but commonly used. We did not conduct any chemical analysis to confirm if these groups were "correct" according to the legal definition, but that doesn't really matter since we were only interested in assessing the genetic relationships. Ten genetic markers called microsatellites (or short tandum repeats, or simple sequence repeats) were used. These are portions of the genetic code which have short repeating sequences of DNA, usually 3-6 nucleotides per unit repeating 8-30 times in a section of DNA.This is a commonly used genetic tool to determine genetic relationships among individuals of closely related species or groups within species (such as cultivars or strains).

Hemp and Drug-type: Clearly Different

What we found was that there was a fairly clear genetic division between hemp and drug-type Cannabis, which could be due to the very heavy selection and cultivation of different types of Cannabis utilized for different purposes. All hemp samples were genetically similar, indicating close genetic relationships. The drug-types also shared genetic identity with one another, but in some cases also had some genetic similarities with hemp. This wasn't shocking since these are all the same species and presumably hemp types are the ancestral form with more recent breeding and selection efforts focused on phytochemical production as opposed to industrial uses.

Sativa, Indica, and Hybrid?

Not surprisingly, there was no clear distinction of Sativa, Hybrid, and Indica subcategories found. Unfortunately, these terms are used to describe either growth characteristics (morphology) OR effects- neither of which has to do with the other.

Where does NIDA fit?

Interestingly, the two analyzed “research grade marijuana” samples obtained from NIDA were genetically distinct from most drug-type Cannabis available from retail dispensaries. Although the sample size was small, “research grade marijuana” provided for research is genetically distinct from most retail drug-type Cannabis that patients and patrons are consuming. Several of the analyses we used took each individual and compared them to every other individual, so the size of the arbitrary groups did not effect the outcome of the test.

We do not claim that NIDA is supplying hemp for Cannabis research, 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.

Autoflowers and C. ruderalis

In the image above you might notice some drug-types that seem to have quite a lot of genetic signal common to hemp (highlighted with pink arrows). I have circled the C. ruderalis sample and it is which clearly is part of the hemp group. Generally, breeders are not interested in C. ruderalis as it is low in THC and has a shorter life cycle because flowering is triggered by age (auto-flower) rather than photoperiod. Some breeders find auto-flowering desirable as photoperiod is not a trigger to flowering, and auto-flowering has been bred into some strains. Although I have no way to verify this, my theory is that these samples in the drug type group with a fairly high hemp genetic signal may be from autoflowering plants. Summary

1. Hemp and Drug-types are genetically differentiated

2. NIDA is genetically different from hemp and drug-types, but is genetically closer to hemp

3. Hemp has a clear genetic signal which is also found in drug types, but the drug type signal is not found in the hemp types, which differentiates the two groups

4. Sativa and Indica types did not resolve genetically in this particular study

5. Hemp signal found in drug types may be from breeding in a C. ruderalis trait to create autoflowering cannabis plants.

*For the record, I hate the term "drug-type" as it implies Cannabis is a drug. However, the term "marijuana" is just as controversial and the current climate discourages the use. An alternative would be hemp and non-hemp types, but when we got into high CBD non-hemp type and high THC non-hemp type, it got very cumbersome and confusing. Another option would be THC- or CBD-types, or Type I and Type III, but as we did no chemical analysis, we also felt these terms to be inappropriate for our article. We had to settle on one, so we chose the categories based on intended use and origin. Dispensary samples were "drug-type".

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