Deborah Agboola   |   September 22, 2020

The Science of Cannabis Genomics

Advanced genetics and genomic fingerprinting in cannabis research.
Deborah is an inquisitive writer with a forte in technical writing. Her desire to enlighten and inform gives her the extra edge of structuring her writes to an easily understandable form, while retaining its technicality. When she is not…

The science of “genomics” refers to the biological study of genomes - encompassing the analysis of their structure, function, evolution, including mapping and editing of these components. A genome, which is the totality of the organism’s genes, can either be subjected to genetics or genomics – noting the comparative difference between them. While genetics involves examining the organism’s DNA (genes) and the effect of inheritance on the genomic expression, genomics involves the collective characterization of the genes, the relationship existing between each gene, and the effects of such associations on the organism.

Although genomics more conventionally involves the collective analysis, its functionality is also applicable in examining a single constituent gene’s effect in the context of its entire genome. Achieving its purpose, genomics, initially initiated by Fred Sanger and his team in the late 1900s, paved the way for the first mapping of the human genome in the 1990s, and the subsequent publication of the human genome sequence in 2003.

Following this, further advancements in this field have enabled the accomplishment of multiple life-science feats, not only in anatomy (or man study) but also in zoology (animal study) and botany (plant study). Understanding ‘what makes up what,’ researchers and problem solvers can now address the challenges facing current situations, like the study of the Sars-Cov-2 virus genomic sequence in the drive to finding a coronavirus vaccine.

CANNABIS GENOMICS

In the world of cannabis, there is a wide variety of cannabis cultivars made from the hybridization of two or more of the currently three known strains: Cannabis sativa, Cannabis indica, and Cannabis ruderalis. The plethora of mixes, which before the advent of genomics would have been formerly considered impossible, are created from the mapping out and fusion of the desired parent strain genomic sequence to identify and highlight favorable traits and create an entirely new kind.

The plant cannabis serves economically as a reservoir of fiber, edible seeds, oils, and several phytochemicals (cannabinoids) unique to the cannabis plant. It has been researched and ascertained that asides cannabis, no other known botanical specie can produce cannabinoids; therefore, inferring that the genes required to form these are peculiar to the cannabis genome. The general classification of cannabis into marijuana and hemp, based on its therapeutic and psychotropic ability, is owed primarily to its THC and CBD content. Using molecular analysis, researchers have noted this: these two compounds originate from a common precursor molecule, CBGA (cannabigerolic acid), but split at the “switch” - the “THCA synthase” or “CBDA synthase” - where the precursor molecule folds into the final product of the prevailing synthase.

Since the mid-1990s, questions on whether a single gene encodes the enzymes responsible for the conversion of CBGA to THC or CBD with two variants or two closely linked genes have risen, causing scientists to delve deeper into this mystery with the science of genomics. In the early 2000s, a Netherland team cross-bred a hemp plant with a marijuana plant - Finola Hemp and Purple Kush; examination of their progeny gave rise to the prior mentioned cannabinoids been controlled by a single gene. This theory, however, went under skepticism after the publication of the first crude cannabis genome using the Purple Kush. Examining the mapping of its genomic sequence, the purple kush, which, if following the proposed theory, should have just a THCA synthase, had resident inoperative copies of CBDA synthase deactivated either by a premature stop codon or an unidentified form of genetic mutation. This phenomenon on the plant remained unknown until the development of advanced technologies, allowing better expression of the former “fragmented” sequence; thereby, unraveling the mystery.

Advancements in cannabis genomics brought to light the reason behind the transformation of a hemp plant into a marijuana plant - further analyses of a cannabis genome showed millions of DNA codons discretely separated into ten chromosomes, with all having similar characteristics but chromosome 6, which held both synthases (“THC synthase” and “CBD synthase”), separated by about 20 million nucleotides. In certain conditions, the retroelements -molecules that possess the ability to evolve themselves and transform other genes - on the chromosome 6, mutate, duplicate and alter the structure of other genes, transforming the entire sequence.

THE BENEFITS OF CANNABIS GENOMICS

The opportunity to projectively analyze final breeds using genomics has brought hemp breeders relief, especially those in no-THC zones (zero-tolerance to marijuana). This benefit also holds for the more marijuana-tolerant areas, as cultivators and breeders can now strive to develop new, improved cultivars.

Genomics has also helped in the artificial synthesis of rare cannabinoids. Experimental research conducted by the infusion of a chromosome-6 duplicated gene into a yeast cell released a rare anti-inflammatory cannabinoid, cannabichromene (CBC), which had a 96% similarity to the THCA synthase at the DNA level and a 93% similarity at the protein level, but without psychotropic abilities.

When used in tandem with other related technologies, genomics is efficiently applicable in purity and quality consistency checks. An example of such integration is the Purity-IQ cannabis fingerprint, which employs genomics in the determination of the cannabis identity and hereditary, and nuclear magnetic resonance in determining the purity and consistency of the product at a molecular level.

In summary, an accurate examination and assembly of the cannabis’ genomic structure will enhance molecular breeding programs by allowing favorable control of yield, flowering time, pest resistance, and cannabinoid expression, not to mention, it will create a better understanding of unexplained and rare phenomena; like hermaphroditism and apomixis.

 

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