The Genetics of THC and CBD
Welcome to part one in our series on the science of cannabis growing and breeding. We’ll be discussing what makes strains different from each other, interesting facts about cannabis growth traits, and how the underlying genetics can be controlled through precise breeding methods. To get started, let’s talk about the genetics of THC and CBD.
These two molecules are produced by a pair of enzymes that convert cannabigerol, or CBG, into either THC or CBD, depending on which enzyme is present.
These two enzymes are actually made from slightly different versions of the same gene!
It’s the same concept as having different versions, also known as alleles, of the hair color gene. One version gives you blonde hair, while the other version gives you black hair, but it’s still just one gene that controls hair color . The same is true for THC and CBD.
Determining Levels of THC and CBD
This is why most strains have either high THC, high CBD, or something close to a even ratio with neither cannabinoid becoming much higher than 15% dry weight. If you’re growing cannabis or hemp from seeds, especially if you’re considering doing any breeding projects, this information is essential to set the foundation for the work you’ll be doing. Check out the image below to get an idea of what the different combinations of THC (Bt) and CBD (Bd) alleles look like at the genetic level.