JUL 12, 2018 11:45 PM PDT

Cannabis Genetics 101

Have you ever wondered about the genetics of Cannabis?  Humans have 46 chromosomes in total; we have a diploid genome (2n = 46) or 22 pairs and two sex chromosomes.  Females have two X chromosomes and males have an X and a Y chromosome.  Yep….this isn’t new to most folks.  However, did you know that the Cannabis plant also has a diploid genome but only has a total of 20 chromosomes.  Each plant cell nucleus has 9 autosomes with a pair of sex chromosomes; an X and a Y just like humans in fact.  Well, not just like humans but kind of.

Human sex chromosomes are vastly different in size; the X chromosome is 155.3 Mb and has approximately 833 genes where the human Y chromosome is 59.4 Mb and contains approximately 72 known genes.   The human haploid genome size equals approximately 3,300 Mb.  Comparatively, the total cannabis genome haploid size is 818 Mb for female species and 843 Mb for males.  The size difference is accounted for by the larger Y chromosome in male plants. 

Gene expression patterns are variable in plants, similar to humans.  In humans, different tissues have different roles so genetic expression is regulated in unique and complex ways.  In plants, most of the cells are similar in form and function; metabolic pathways and expression are far less diverse, but still manage to produce different phenotypes.  For example, the flower cells of the cannabis plant show expression patterns for cannabinoids and terpenoids in all phases of flower development compared to the rest of the plant components.  The highest density of trichomes, which produce cannabinoids, are found within the female plant flowers. 

One group of researchers found expression differences between marijuana and hemp and determined that these were due to small genetic variations that directly or indirectly change gene expression and which enzymes and cannabinoids are synthesized more.  In one cannabis strain, a key enzyme called 9-tetrahydrocannabinolic acid synthase (THCAS) is expressed at higher levels and results in higher amounts of THC; in another strain, the enzyme cannabidiolic acid synthase (CBDAS) is expressed at higher levels leading to increased CBD presence and decreased presence of THC. 

It is interesting to think, just for a moment, about the similarities and differences between plants and humans which starts at the level of our DNA; in how cellular machinery and genetic components work together to express a particular phenotype and have the power to change the end product in such a way.  It is still remarkable when you stop and really consider it. 

Sources: Genome Biology, PLOS One, ResearchGate,

 

About the Author
  • Mauri S. Brueggeman is a Medical Laboratory Scientist and Educator with a background in Cytogenetics and a Masters in Education from the University of Minnesota. She has worked in the clinical laboratory, taught at the University of Minnesota, and been in post secondary healthcare education administration. She is passionate about advances and leadership in science, medicine, and education.
You May Also Like
SEP 17, 2019
Cannabis Sciences
SEP 17, 2019
The Use of Cannabis in Treating Fibromyalgia
It has been found that 90% of patients that are diagnosed with fibromyalgia are women, and only a decade ago doctors thought this condition wasn't real...
SEP 17, 2019
Cannabis Sciences
SEP 17, 2019
Are CBDs Safe for Pregnant Women?
Cannabidiol (CBD) oils have been reported to have amazing health effects, from pain relief to anxiety relief to even cancer prevention. However, in using a...
SEP 17, 2019
Cannabis Sciences
SEP 17, 2019
SXSW's New Marijuana Line-Up
The cannabis info website, Leafly.com, has just broken the news about how SXSW (that little gathering in Austin, TX) will be introducing a bit of...
SEP 17, 2019
Cannabis Sciences
SEP 17, 2019
Sweets or Sweat? Let Your Endocannabinoid System Decide
We all (well, I do) wish we could work out more, but when think about going to the gym we tend to promise ourselves that "we'll do it tomorrow, I...
SEP 17, 2019
Cannabis Sciences
SEP 17, 2019
What are Terpenes and What do They Have to Do With Pot?
Some of you who have been dipping into the marijuana research from time to time may have heard the word "terpenes" come up in the latest sci...
SEP 17, 2019
Cannabis Sciences
SEP 17, 2019
The Munchies Diet?
While marijuana research is ramping up to catch up with the pace of legislation, we should not forget about the characteristic effects of pot. The stereoty...
Loading Comments...