SEP 17, 2019 11:45 PM PDT

Cannabis Genetics 101

WRITTEN BY: Mauri Brueggeman

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
NOV 05, 2020
Health & Medicine
Medical Cannabis Reduces Chronic Pain and Opioid Use
NOV 05, 2020
Medical Cannabis Reduces Chronic Pain and Opioid Use
Researchers affiliated with the University of Haifa in Israel have reported on the efficacy of medical cannabis use for ...
NOV 13, 2020
Health & Medicine
Cannabis Oil May Help Burning Mouth Syndrome
NOV 13, 2020
Cannabis Oil May Help Burning Mouth Syndrome
If you’ve ever scalded the top of your mouth with very hot food or drink you'll know the pain it can cause. No ...
DEC 22, 2020
Health & Medicine
Cannabis Use May Help People on an Opioid Detox Program Stay on Track
DEC 22, 2020
Cannabis Use May Help People on an Opioid Detox Program Stay on Track
New research suggests that cannabis use by people being treated for opioid addiction might improve outcomes and reduce t ...
JAN 09, 2021
Cannabis Sciences
Cannabis Use Does not Increase Risk of Heart Disease
JAN 09, 2021
Cannabis Use Does not Increase Risk of Heart Disease
Previous studies on how cannabis affects cardiovascular health have delivered mixed results. Now, from a study of over 5 ...
FEB 18, 2021
Cannabis Sciences
No Link Between Cannabis Legalization and Public Health Issues
FEB 18, 2021
No Link Between Cannabis Legalization and Public Health Issues
Researchers from the Cato Institute have published a report suggesting no link between the legalization of recreational ...
APR 01, 2021
Health & Medicine
Safety and Contamination Concerns Over Hemp Products
APR 01, 2021
Safety and Contamination Concerns Over Hemp Products
  When the 2018 Farm Bill legalized the regulated production of low-THC hemp, as distinct from other cannabis plant ...
Loading Comments...