Cannabis genetic testing is integral in understanding and predicting the landscape of medicinal compounds that the plant can produce. Solid genetic architecture is the fountain of a sustainable and productive cannabis operation. However, despite the plant being genetically capable of producing certain compounds, environment and cultivation methods may play a substantial role. For this reason, Cannabis genetics can be divided into genotype and phenotype testing. Genotype testing involves analysis of the genes inherited from the parent plants. This acts as a blueprint for what the plant can produce if environmental conditionals are suitable. If the genes necessary for producing a compound are not present, the plant cannot produce the compound. In contrast, phenotype testing means evaluating the observable traits of the plant such as color, smell, and concentration of compounds.
Cannabis genetic testing can be implemented to screen seedlings for early determination of whether the plant contains the desirable traits for breeding. One such desirable trait that Cannabis genetic testing can unveil is the synthase enzyme responsible for converting cannabigerolic acid (CBGA) to tetrahydrocannabinolic acid (THCA) or cannabidiolic acid (CBD). A productive enzyme that converts CBGA to THCA will result in a plant that can produce more delta-9-tetrahydrocannabinol (THC). Similarly, if the gene responsible for that same conversion was mutated or missing nucleotides, this would result in a less productive enzyme, and less THC ultimately produced. Cornell University credits this genetic difference as being a classifier between “hot” hemp or legal hemp.
Toth et al [1] validated a high-throughput method known as PCR [polymerase chain reaction] Allele Competitive Extension (PACE) capable of testing plant genes for predominant THCA, CBDA, or combined cannabinoid production. Their method relies on RNA sequencing and algorithms to identify gene expression. Another genetic testing technology, available as GenKit™ from Steep Hill Labs, tests the DNA of seedling samples to determine whether they are male or female, which is critical for cultivators.
Further than cultivar authentication and genotyping, genetic testing can aid in pathogen detection in Cannabis. PCR and quantitative PCR amplify DNA or RNA fragments of microbes to indicate their presence more accurately than traditional methods.
Complete genetic profiling, or genomics, is possible through next generation sequencing (NGS). [2] As the name suggests, this is a newer method for in-depth analysis of genetic material. NGS involves extracting the DNA from a Cannabis sample, then sequencing millions of small fragments of DNA. After sequencing, the fragments are pieced together, allowing labs to determine what genes comprise the genome of the plant. [2] Eurofins Genomics describes using NGS to identify cultivar, plant sex, pathogens, and disease resistance. By comparing a reference genome with the important genes involved in the synthesis of cannabinoids and terpenes along with other important genetic markers like pathogen-resistant genes, laboratories can determine the quality and potential of the plant genome. Genomic profiling also opens the door to designing unique plants and transforming the growth outcomes of Cannabis.
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[1] Toth JA, et al. Development and validation of genetic markers for sex and cannabinoid chemotype in Cannabis sativa L. GCB Bioenergy. 2020;12:213– 222. https://doi.org/10.1111/gcbb.12667. [Impact Factor: 5.316; Times Cited: 13 (Semantic Scholar)] [2] Behjati S, Tarpey PS. What is next generation sequencing? Arch Dis Child Educ Pract Ed. 2013;98(6):236-238. doi:10.1136/archdischild-2013-304340. [Impact Factor: 1.407; Times Cited: 148 (Semantic Scholar)]
