A study led by a Dalhousie researcher is providing a clearer picture of the evolutionary history and genetic organization of cannabis. It's a step that could have significant agricultural, medical and legal implications for a crop whose importance in health and other fields continues to grow.
“The cultivation of hemp and marijuana represent significant global industries, but our understanding of them lags far behind our understanding of similarly valuable agricultural crops,” says Sean Myles, assistant professor in the Faculty of Agriculture at Dalhousie and Canada Research Chair in Agricultural Genetic Diversity.
The research was conducted together with Anandia Laboratories, a Vancouver-based Cannabis R&D company. Dr. Myles and his team looked at the genetic code of 81 marijuana and 43 hemp DNA samples. They found that hemp and marijuana are easily distinguishable at the DNA level.
Canada is a global leader in hemp production, with more than 80,000 acres devoted to seed and fibre production. “Identifying the genetic differences between hemp and marijuana has legal implications and will help with forensic applications,” says Dr. Myles.
Their work promises to shake up the medical marijuana industry as it casts serious doubt on the naming conventions currently used. “We found that strains were often more genetically similar to strains with different names than they were to strains with the same name," says Dr. Myles. "So, what you see is often not what you get: a strain’s genetic identity cannot be reliably inferred by its name."
Popular lore assigns different characteristics to marijuana plants. For example, Indica-type plants are believed to produce relaxing and sedative effects as opposed to more stimulating Sativa-type plants. The researchers found only a moderate correlation between the ancestry of marijuana strains reported by breeders and the ancestry inferred from their DNA. For example, a sample of Jamaican Lambs Bread, which is classified as C. sativa, was almost identical at a genetic level to a C. indica strain from Afghanistan.
“Cannabis breeders and growers often report the percentage of Sativa or Indica in a cannabis strain, but they are not very accurate,” explained Jon Page, president and CEO of Anandia Labs, which co-led the study.
A license from Health Canada is required to grow marijuana for medical purposes and there are now 25 licensed producers supplying about 21,000 Canadian patients. Understanding cannabis genetics and evolution could assist in better breeding efforts for both crops.
“The enormous medicinal and commercial potential of cannabis can only be realized if a reliable classification system is established," says Dr. Myles. “Imagine if your expensive bottle of Pinot Noir [wine] or bag of Honeycrisp apples did not contain the varieties printed on their labels. Marijuana is fortunate to be in the company of grapes and apples: consumers’ fascination with its diversity is arguably unrivalled among crops. Marijuana producers need to step up their genetics game so they can capitalize on the benefits of telling their customers the truth.”
The findings were published late last month in the journal PLoS ONE.
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