Seedsman Blog

Tracing The Genetic Heritage Of Your Cannabis

The variety of cannabis strains on the market seems to be forever expanding, which means you really need to know your Purple Kush from your Gorilla Cheese if you want to navigate your way through all that choice. And while this abundance of cultivars is obviously a good thing, all the genetic mixing and matching that has gone into the creation of these strains has made it harder to verify a plant’s genetic heritage.

This means that while you might think you’re buying a Sour Diesel or a Haze, for example, the DNA in your product may not match up with the original genetics of these strains. As a result, you could find that you don’t experience the energetic high you were expecting from your Sour Diesel or the creative buzz you were hoping for from your Haze.

Obviously, the best way to ensure the genetic integrity of your cannabis seeds is to buy them from a trusted outlet, as black-market dealers and local breeders may lack the incentive or the competence to guarantee that their merchandise is truly what they say it is. Yet to fully grasp the complexity of this issue it’s necessary to understand a thing or two about cannabis genetics.

A History of Mixing and Matching

Cannabis is believed to have originated in Central Asia, but was transported around the world and cultivated by numerous ancient civilisations thousands of years ago. A combination of selective breeding by humans and natural selection as the plant adapted to its various new environments led to the establishment of the earliest cannabis strains, known as landrace strains.

Emerging in places like Afghanistan, India, Colombia, Mexico and Malawi, each landrace had its own unique genetic profile and characteristics – or genotype and phenotype, to use the scientific terms. As time went on, these landraces became the forefathers for all modern strains, which have been created through countless rounds of cross-breeding and in-breeding in order to select for specific phenotypes.

For example, many of the Afghan landraces were of the Indica variety, which is known for its calming effects. Over the years, breeders have created numerous Indica strains by crossing these ancient Afghan cultivars with other varieties or with themselves, producing an array of relaxing cannabis strains. Yet while many breeders like to proclaim the Afghan heritage of their crop by naming it in honour of the country, no one is checking to see if these new strains still bear any genetic resemblance to the old landraces.

A Tangled Web

If the original landraces could be neatly categorised according to their genotypes and phenotypes, the spiralling array of modern strains has become something of a tangled web of genetics. To prove the point, a team of researchers recently analysed 30 different cannabis strains and found significant genetic inconsistencies between different samples of each strain, illustrating how years of cross-breeding has jumbled up the cannabis genomes, making it harder to find genetically trustworthy cultivars.

The study, which appeared in the Journal of Cannabis Research last year, included strains such as Bruce Banner, Flo, Jillybean, Pineapple Express, Purple Haze, and Tangerine, all of which are supposed to contain a 60:40 ratio of Sativa to Indica. Yet the team found that each of these strains had a totally different composition of Sativa and Indica genes, reinforcing the fact that many cannabis products on the market are not of the genetic stock that they claim[i].

The Future Of Genetic Testing

Researchers are currently developing a method to provide a detailed genetic analysis of cannabis products. According to a study that appeared last year in the journal Plant Physiology, a team of scientists was able to identify the genes responsible for the synthesis of all of the cannabinoids and terpenes present in the plant, using a technique called RNA-sequencing. Having achieved this, they were then able to determine the exact genetic profile of nine different cannabis strains, revealing how the chemical composition of each cultivar is reflected in its genotype[ii].

In theory, this method could one day be used to create a database listing the genome of every cannabis strain, which would enable breeders to verify the genetic authenticity of their crop. It could also allow growers to identify female plants from their genetic profile rather than waiting for them to flower, which would increase efficiency by enabling for earlier separation of males and females.

Until then, it’s best to stick to a trusted outlet that sells only top quality cannabis products.


[i] Schwabe AL, McGlaughlin ME. Genetic tools weed out misconceptions of strain reliability in Cannabis sativa: implications for a budding industry. Journal of Cannabis Research. 2019 Dec;1(1):3. – https://jcannabisresearch.biomedcentral.com/articles/10.1186/s42238-019-0001-1

[ii] Zager JJ, Lange I, Srividya N, Smith A, Lange BM. Gene networks underlying cannabinoid and terpenoid accumulation in cannabis. Plant physiology. 2019 Aug 1;180(4):1877-97. – http://www.plantphysiol.org/content/180/4/1877

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Ben Taub