Cannabis Genetics: Sativa, Indica, and Hemp is there a difference?

Introduction

Whenever you read a scientific paper about cannabis it always starts the same way – cannabis has been used by humans for thousands of years as far back as 12000 BCE for fiber, food, medicinal, and psychoactive effects, blah blah blah – we all know this story well right.

We also know that besides the variety of words to refer to cannabis itself, there is an ever-growing list of names for all these seemingly specific strains or plant varieties. We have the classics such as Maui Waui, White Widow, Purple Haze, Diesel, and the list goes on. But Kimit, if I asked you to tell me what the chemical profile, breed, and origin was for OG Kush bought in my neighborhood dispensary was, would you be able to?

With the recent explosion of the international cannabis industry, these questions have become more important than ever.

Question

There are two main questions here. First, are there three sub-species of cannabis (C. Sativa, C. Indica, and Hemp) or various varieties of the same species? Second question is, does the name and reported ancestry of a strain really reflect its genetic and chemical profile, suggested by the Indica and Sativa classifications?

Results

Scientific Taxonomic Classification

The first attempts to figure this out came from studies looking at different ripening stages of cannabis, then later different phenotypes or differences in cannabinoid content, establishing what’s known as drug-type and fiber-type cannabis. They would refer to plants with high THC content and low CBD content as “drug-type” and those with low THC and high CBD as “fiber-type”.

This may sound logical, but it isn’t. Principally because there are no strict natural relationships between fiber characteristics and cannabinoid content. The main problem here is that cannabinoid ratios are governed by genetic factors that even in sister plants can have very different chemical profiles. So, we can’t use chemical profile as a taxonomic criterion.

Yet for legislative purposes, this seems to be the most important classification. Whether a plant is drug-type (marijuana) or fiber-type (hemp). The main difference for “fiber-type” being that the flowers or upper reproductive parts have ~0.3% THC or less.

But it isn’t so simple, we now know that classification goes far beyond THC and CBD content.

What about the terpenes, can they be used to classify cannabis types?

All mayor terpenoids found in Cannabis can be found everywhere in nature.

Based on recreational user experience, the Sativa’s are often characterized by an uplifting, energetic, and mostly cerebral high. Whereas, the Indica’s are most often described as a pleasant body high, supposedly useful for overall pain relief, and insomnia. Yet, despite some work exploring this more scientifically it has yet to be properly confirmed whether this is true or not.

Based on research done in the Netherlands by some colleagues of mine in 2011, they looked into whether terpenes can be used to classify these varieties. Let’s use two strains as examples,

the sativa-dominant Amnesia and Indica-dominant White Widow

Amnesia sample were found to mainly have the presence of terpenoids: terpinolene, alpha-guaiene, gamma-selinene which were not found in White Widow.

White Widow showed significantly higher myrcene and alpha-pinene, than Amnesia. It also had guaiol, beta-eudesmol, gamma-eudesmol, and alpha-bisabolol. Sesquiterpene alcohols are important markers for Indica from Afghanistan.

Despite no difference in average major cannabinoid content (THC and CBD) between Sativa and Indica. Yet, a more prominent difference can be found in terpene composition, specifically the presence of hydroxylated terpenes in the Indica group. These include, guaiol, eudesmol, fechol, alpha-terpineol, linalool, geraniol, camphor. This relationship remains tenuous at best.

What about the genetics of the plant’s themselves? Have people sequenced different cannabis strains to check for differences in the DNA?

That seems to be the direction most labs are taking now. A few studies have been published recently about this.

For example, a study formed by a transnational US collaboration which included the University of Colorado and Steep Hill Labs used a technique called nuclear genomic diversity (measuring precise genetic differences within specific genes which helps figure out evolutionary relationships). The analyzed 340 cannabis varieties including hemp for fiber and seed oil, high-cannabinoid drug types, and feral or wild populations from both North America and Asia.

This work led to the designation of 2 main groups. Narrow Leaflet Drug-Types (NLDT) (Sativa-like) and Broad Leaflet Drug-Types (BLDT) (Indica-like).

European hemp varieties a more closely related to Sativa-like, which has a much larger geographic range. Broad Leaflet Drug-Type or Indica-like groups appears to be less diverse than Sativa’s, suggesting a more recent origin of domestication. As one would expect, Afghan Kush landrace samples cluster around Indica-like.

Interestingly, Sativa-like strains seem to be very genetically similar and may be due to extensive indoor cloning techniques starting in the 1970s.

Strains like AC/DC (High CBD) and feral varieties more closely match to hemp groups which are Sativa-like.

Guess what NY Sour Diesel matched to? It actually matched to Indica-type. What about G13? Sativa-like

Yet, it appears that in general the average genetic difference between hemp and marijuana is similar to the degree of genetic difference in humans between Europeans and East Asians. So, while cannabis breeding has resulted in clear genetic differentiation based on use, hemp and marijuana still largely share a common pool of genetic variation.

Regarding Sativa vs Indica though, the study proposes that Sativa and Indica may represent individual pools of genetic diversity, but that breeding has resulted in a considerable mixing between the two.

Ancestry and genetics often do not match

It seems that very often the assigned ancestry (or name) strongly deviates with the genotyped data.

For example, Jamaican Lambs Bread (reported Sativa to be a 100% Sativa) was nearly identical to a 100% Indica reported strain from Afghanistan. This inaccuracy of the ancestry reported could be due to many things, but what this does highlight is that the cannabis strain name does not necessarily represent a genetically unique product.

Especially because samples with identical names were compared to each other and other samples. They found that in 6 of 17 sample comparisons (35%), some strains were genetically more similar to samples with different names than to samples with the same name. This highlights what most cannabinologist like me have been advocating for a long time, and that is that the genetic identity of a strain cannot be reliably inferred by its name or reported ancestry.

Conclusion

The take home message here is simple, when you order online or go to the dispensary just because someone tells you that a cannabis product they are selling is a specific strain with set of specific effects, take what they say with a grain of salt. With the things the way they stand now I recommend exploring different products to see what you like. Sadly, you may buy one product one day then try to get it again the next and it could be completely different. Enjoy the search though, don’t get bogged down on names. Smell and taste the products to see what you like. It is as much an emotional and sensory experience, as it is a pharmacological one.  So, if you want to get consistency, I can only recommend cannabis from Bedrocan BV in Holland, otherwise there are a few other companies in Canada, but I will not say the name on the air at this moment. And if this doesn’t satisfy you maybe you should grow your own plants to know at least what you are consuming.


References

Lynch, et al. Genomic and chemical diversity in cannabis. Critical Reviews in Plant Sciences. 2016

Hazekamp A., Fischedick JT. Cannabis-from cultivar to chemovar. Drug Testing and Analysis. 2011

Sawler J et al. The genetic structure of marijuana and hemp. Plos One. 2015

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