Using firefly genes to understand the biology of cannabis

Highlight it: Using firefly genes to understand the biology of cannabis

Yi Ma near cannabis plants in the CAHNR greenhouse. Credit: Jason Sheldon / UConn Photo

Cannabis, a plant that is attracting increasing attention due to its extensive medicinal properties, contains dozens of compounds known as cannabinoids.

One of the most famous cannabinoids is cannabidiolic acid (CBD), which is used to treat pain, inflammation, nausea and more.

Cannabinoids are produced from trichomes, small spikes protruding on the surface of cannabis flowers. Apart from this fact, scientists know very little about how cannabinoid biosynthesis is controlled.

Yi Ma, a research assistant, and Gerry Berkowitz, a professor at the College of Agriculture, Health and Natural Resources, studied the major molecular mechanisms behind trichrome development and cannabinoid synthesis.

Berkowitz and Ma, along with former students Samuel Hayden and Peter Apichela, discovered transcriptional factors responsible for trichoma initiation and cannabinoid biosynthesis. Transcription factors are molecules that determine whether part of the body’s DNA will be transcribed into RNA and thus expressed.

In this case, the transcription factors cause epidermal cells on the flowers to transform into trichomes. The discovery of fate was recently published as an article in Plants. A related study of trichoma has also been published in Plant directly. Due to the potential economic impact of the gene, UConn has filed a temporary patent application for the technology.

Based on their findings, researchers will continue to investigate how these transcription factors play a role in the development of trichoma during flower ripening.

Berkowitz and Ma will clone the promoters (the part of DNA to which transcription factors bind) of interest. They will then place the promoters in the cells of a model plant along with a copy of the gene that causes fireflies to glow, known as firefly luciferase; luciferase is fused to the cannabis promoter, so if the promoter is activated by a signal, the luciferase reporter will generate light. “This is a great way to evaluate the signals that organize cannabinoid synthesis and trichoma development,” Berkowitz said.

The researchers will load the cloned promoters and luciferase into a plasmid. Plasmids are circular DNA molecules that can replicate independently of chromosomes. This allows scientists to express interesting genes even though they are not part of the plant’s genomic DNA. They will supply these plasmids to the leaves or protoplasts of plant plants without the cell wall.

When the promoter controlling luciferase expression comes into contact with the transcription factors responsible for the development of trichoma (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 researchers whether the promoter regions they are considering are under control transcription factors responsible for increasing the development of trichomes or modulating genes that encode cannabinoid biosynthetic enzymes. They can also learn whether promoters respond to hormonal signals.

In a previous paper that underpinned this experimental approach, Ma and Berkowitz, along with graduate student Peter Apichela, found that the enzyme that produces THC in cannabis trichomes may not be the critical restrictive step in regulating THC production, but rather, the generation of the precursor for THC (and CBD) and the transport facilitated by the transport of the precursor to the extracellular bulb may be key determinants in the development of cannabis strains with high THC or CBD.

Most cannabis growers grow hemp, a variety of cannabis with naturally lower THC levels than marijuana. Currently, most varieties of hemp that have high levels of CBD also contain unacceptably high levels of THC. This is probably because hemp plants still produce the enzyme that produces THC. If the plant contains more than 0.3% THC, it is considered illegal and in many cases must be destroyed. A better understanding of how the plant produces THC means that scientists can selectively destroy the enzyme that synthesizes THC using genome editing techniques such as CRISPR. This would produce plants with lower levels or without THC.

“We anticipate that the fundamental knowledge gained can be translated into new genetic tools and strategies to improve the cannabinoid profile, help hemp farmers with the common problem of THC overproduction and benefit human health“, Say the researchers.

On the other hand, this knowledge can lead to the production of cannabis plants that produce more than desired cannabinoidswhich makes it more valuable and profitable.

The colder the flower, the more powerful the cannabis

More info:
Samuel R. Haiden et al, Overexpression of CsMIXTA, a transcription factor from Cannabis sativa, Increases the density of glandular trichomes in tobacco leaves, Plants (2022). DOI: 10.3390 / plants11111519

Peter V. Apicella et al, Outlining the genetic regulation of cannabinoid biosynthesis during the development of female flowers in Cannabis sativa, Plant directly (2022). DOI: 10.1002 / pld3.412

Quote: Light it up: Using firefly genes to understand the biology of cannabis (2022, June 21), retrieved on June 21, 2022 from -cannabis-biology.html

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