The cannabis industry is booming. More and more countries are legalising the plant for medical and recreational use, with many states in the USA leading this process. Despite the plant being illegal to possess for most of the past century, breeding of cannabis has continued for many years and has now led to the development of a wide range of medical and recreational varieties that many consumers are familiar with. These varieties are commonly referred to as ‘strains’. The idea behind this concept is that different strains will have different characteristics, such as appearance, fragrance profile and effects. But where do these differences arise from? The genetic background is an important factor; for instance, research has shown that the terpenoid profile of cannabis is determined largely by its genetics, while the cannabinoid content can be influenced more heavily by the environment¹. The entourage effect, covered in a previous newsletter, is instead thought to be responsible for different effects that growers and cannabis enthusiasts associate with different strains. This notion is, however, still highly contentious and conclusive research on the topic has not been conducted yet².

One major issue facing the industry is the lack of consistency among cannabis strains. Let us take the USA as example. The United States Department of Agriculture (USDA) is responsible for protection “against commercial exploitation, trademarking, and recognition of intellectual property for developers of new plant cultivars”. However, cannabis varieties have yet to be included  in this scheme of legal protection (United States Department of Agriculture 2014). Because they are not officially regulated, the only information consumers can rely on when buying a specific strain is the label that the retailer uses. This lack of regulation leaves room for mislabelling (intentional or not) and for a general lack of consistency among different retailers, even for products labelled in the same way and supposedly grown from the same seeds. Recent research investigating this topic has pointed out some of these inconsistencies in the USA cannabis market³. The authors investigated 30 different strains acquired from dispensaries across three different states, and applied a type of genetic analysis commonly used to distinguish between crop varieties of the same species. Not surprisingly, most strains presented genetic inconsistencies and contained at least one sample that was a complete outlier (Fig.1).  

The authors point out, however, how after removal of the outliers most strains showed some form of genetic stability across dispensaries. These results indicate that the many years of illegal breeding were successful in creating “stable” cannabis varieties, but highlight how the lack of regulation still allows genetically unrelated strains to be sold under the same name³. This can cause confusion and frustration among consumers, who may not be getting the product they think they are buying. More importantly, this lack of consistency can be problematic for patients who rely on specific strains for medicinal purposes, as they may not be getting the consistent effects they need. Moreover, the authors found out that the marketed classification of cannabis strains into “sativa/indica/hybrid” categories (newsletter 5) did not have an underlying genetic basis.

The sort of genetic analysis carried out by the authors could become the basis for regulating cannabis varieties similarly to what happens for other agricultural products, eventually reducing the possibilities for mislabelling and inconsistencies. However, classification of cannabis solely on genetic background has some limitations. In fact, the totality of a plant’s observable characteristics, technically referred to as the phenotype, is determined by an interaction of its genetics with the environment. This is true for all plants, but cannabis has proven to be extremely plastic in this sense, meaning that two genetically identical seeds can produce very different phenotypes when subjected to different growth conditions⁴. This  means producing flowers with different ratios of various cannabinoids and terpenes, which in turn might cause the product to have a different effect when consumed. This limitation can be overcome by the chemical analysis of the compounds present in a specific batch following production⁵. Research has shown that classification of cannabis strains based on their chemical “fingerprint” is possible, as shown by a study that examined 30 different strains from a medical dispensary in the U.S.A. Based on their shared similarities in terms of terpenoid profile, the authors were able to group the strains into five major categories subdivided in 13 classes⁶. The same authors also showed, in another study, how it was possible to discriminate among 11 different strains solely based on their chemical profile⁷. This sort of classification based on chemistry would allow consumers to identify comparable products when one should not be available for purchase. Additionally, it could point out differences between strains sold under the same label from different retailers (or from the same retailer over time!) that would otherwise be impossible to notice .

Consistency of strains still represents a major weakness in the cannabis industry that will need to be addressed in the future. This can be achieved through official regulations and standardisation of strains, possibly with the use of a combination of genetic and chemical analyses. Third-party testing and certification of cannabis varieties will help to ensure that consumers are getting the products they think they are buying, and that patients have access to the strains they need for medicinal purposes. This positive impact will not be limited to the user’s experience, but will also help to improve the overall reputation and credibility of the industry.