Genetics of marijuana decrypted

Genes make the difference in the effect

10/21/2011

In a genome analysis, Canadian researchers have discovered why many hemp varieties contain tetrahydrocannabinol (THC) in intoxicating amounts, but not hemp.

The University of Toronto scientists compared the genomic structure of commercial hemp with that of particularly THC-containing marijuana of the variety „Purple Kush“. The researchers discovered the molecular causes that cause some hemp plants have a special intoxicating effect, while others remain completely without effect.

530 million building blocks of the marijuana genome
The researchers around Jon Page and Tim Hughes from the University of Toronto sequenced the genome of the marijuana strain „Purple Kush“ and then compared their results with the already known genomic structure of commercial hemp. „Purple Kush“ Like all marijuana strains, it was derived by targeted breeding from conventional hemp (cannabis sativa). However, the original plant has only such low levels of tetrahydrocannabinol (THC) that it does not exert any intoxication. „Purple Kush“ however, one of the most THC-containing varieties. The Canadian scientists present in the current issue of the journal „Genome Biology“ the complete genome of the special marijuana variety and contrast this with the genome of the original hemp plant. Around 30,000 genes with a total of more than 530 million building blocks of the „Purple Kush“ list the experts in their contribution.

Discovered THC producing enzyme
When comparing the genome of hemp and „Purple Kush“ In particular, researchers paid attention to the differences in the enzymes involved in THC production. Page and Hughes discovered it here „Purple Kush“ an enzyme that produces the psychoactive substance - 9-tetrahydrocannabinoleic acid synthase. In addition, let „The detailed analysis of both genomes suggests that conversion, cultivation and breeding have led to the loss of another enzyme (Purple Kush)“, so the statement of the experts. So missing in the heady marijuana strains and the enzyme „CBDA synthase“, which converts the chemical precursors of THC to other substances so that less THC is formed. As these competing use in „Purple Kush“ Clearly, significantly more starting material remains that can be used for THC production, Page and Hughes explained.

Improving the medical use of THC
The Canadian researchers' findings are also of particular medical importance, as the use of marijuana as a drug is primarily aimed at the effect of the contained THC. The medical prescription or the therapeutic use could be so explicitly directed to hemp varieties that contain much of the enzyme 9-tetrahydrocannabinoleic acid synthase. Also, the discovery of the THC-producing enzyme offers new approaches to the future breeding of marijuana plants. (Fp)

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Picture: Susanne Schmich