"Will help growers better control CBD and THC levels"

Light it up: Using firefly genes to understand cannabis biology

Yi Ma, a research assistant professor, and Gerry Berkowitz, professor in the College of Agriculture, Health and Natural Resources, received funding through the National Research Initiative from the U.S. Department of Agriculture to discover the underlying molecular mechanisms behind trichrome development and cannabinoid synthesis.

Berkowitz and Ma will clone the promoters (the part of DNA that transcription factors bind to) of interest. They will then put the promoters into the cells of a model plant along with a copy of the gene that makes fireflies light up, known as firefly luciferase; the luciferase is fused to the cannabis promoter, so if the promoter is activated by a signal, the luciferase reporter will generate light. “It’s a nifty way to evaluate signals that orchestrate cannabinoid synthesis and trichome development,” says Berkowitz.

When the promoter controlling luciferase expression comes into contact with the transcription factors responsible for trichome development (or triggered by other signals such as plant hormones), the luciferase ‘reporter’ will produce light. Ma and Berkowitz will use an instrument called a luminometer, which measures how much light comes from the sample. This will tell the researchers if the promoter regions they are looking at are controlled by transcription factors responsible for increasing trichome development or modulating genes that code for cannabinoid biosynthetic enzymes. They can also learn if the promoters respond to hormonal signals.

In prior work underlying the rationale for this experimental approach, Ma and Berkowitz, along with graduate student Peter Apicella found that the enzyme that makes THC in cannabis trichomes may not be the critical limiting step regulating THC production but rather the generation of the precursor for THC (and CBD) production and the transporter-facilitated shuttling of the precursor to the extracellular bulb might be key determinants in developing cannabis strains with high THC or CBD. “We envision that the fundamental knowledge obtained can be translated into novel genetic tools and strategies to improve the cannabinoid profile, aid hemp farmers with the common problem of overproducing THC, and benefit human health,” the researchers say.

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Publication date: Wed 22 Jun 2022