The entourage effect, a term commonly used in the cannabis industry, refers to the combined effects of cannabinoids and terpenoids on a consumer’s psychological perception of different cannabis varieties. Each strain of cannabis contains varying concentrations of cannabinoids, including psychoactive tetrahydrocannabinol (THC) and non-psychoactive cannabidiol (CBD), as well as a unique terpenoid profile. This allows consumers to choose cannabis based on desired effects and specific aromas. However, while there is widespread information about the characteristics of different strains, the underlying genetic information that accounts for these differences remains poorly understood.
Genetic testing holds significant benefits for cannabis breeders, producers, and consumers. In a recent study conducted by Bernd Markus Lange, PhD, professor at the Institute of Biological Chemistry, and director of the MJ Murdock Metabolomics Laboratory at Washington State University, along with Anthony Smith, president and CSO of EVIO Labs, Inc., metabolic and transcriptomic data sets were analyzed to differentiate cannabis strains. The findings from this study are not only relevant for the development of new cultivars but also help ensure that consumers are able to select appropriately labeled products. Additionally, for breeders and producers, the ability to determine the sex and cannabinoid type of young plants is crucial. To address this need, Jacob Toth and his colleagues at Cornell University developed high-throughput assays specifically designed for this purpose.
To understand how genetic testing can contribute to the field of cannabis engineering and production, it is important to have a basic understanding of plant biology. Cannabinoids and terpenoids are primarily concentrated in the flowers of Cannabis plants within glandular trichromes. These trichromes are modified hairs found in many flowering plants that synthesize and store metabolites as oils or resins. While cannabinoids and terpenoids do not share biosynthetic pathways, they do use similar chemical building blocks. For example, sesquiterpene and monoterpene compounds are enzymatically synthesized from a precursor called isopentenyl diphosphate (IPP), which also contributes to the production of cannabinoids.
Cultivars are plants that share similar morphological, physiological, and chemical characteristics and maintain these traits through reproduction. Chemotypes, on the other hand, are classified based on their chemical composition, including cannabinoids and terpenes. Previous research has identified distinct chemotypes in cannabis based on the cannabinoids they produce. These include mostly THC (type one), about equal THC:CBD (type two), and mostly CBD (type three). The genetic basis of these chemotypes has been determined to be a single major locus.
To address the need for rapid and efficient assays to identify plant sex and cannabinoid type, high-throughput methods such as PACE (PCR Allele Competitive Extension) have been developed. These assays allow breeders and suppliers to test young plants for their cannabinoid type and sex, enabling early separation of male and female plants. This is particularly important because male and female cannabis plants are phenotypically similar until they mature and begin to flower.
By combining metabolomic and transcriptomic data using RNA-seq and algorithms, researchers such as Lange and Smith have successfully identified distinct gene networks in cannabis strains. RNA-seq offers advantages over traditional genotyping methods as it does not require prior knowledge of specific gene targets. It provides a sensitive and accurate account of all genes expressed above a certain threshold in the tissues or cell types being studied. In addition to RNA-seq, gas chromatography (GC) and liquid chromatography (LC) are used to separate and quantify cannabinoids and terpenoids. GC is particularly effective for analyzing volatile terpenes, while LC is more suitable for cannabinoid separation.
The benefits of genetic testing in the cannabis industry are far-reaching. From helping growers remain compliant with respect to THC content to aiding in the development of new cultivars and informing consumers’ purchasing decisions, genetic testing plays a vital role. Cannabis breeders and suppliers can benefit from the genetic information obtained through high-throughput assays, as it allows for early identification of desirable traits and elimination of undesirable plants without expensive phenotyping.
However, there are still practical and legal challenges that need to be addressed. Issues such as sample mix-ups, specialized equipment requirements, and high costs per sample pose obstacles to widespread adoption of genetic testing in the cannabis industry. Furthermore, the regulatory landscape surrounding cannabis testing varies by state and lacks predictability, creating additional challenges for industry stakeholders.
Despite these challenges, the increasing availability of high-quality genome sequences and the continued advancements in genomics and phenotyping have paved the way for significant progress in cannabis breeding and engineering efforts. As we continue to improve our understanding of the genetic basis of cannabis strains, genetic testing will undoubtedly play a crucial role in ensuring successful cannabis production, engineering, and purchasing.
