New PM2 Gene Discovery by Aurora Cannabis Enhances Disease Resistance

Cannabis Growth

Cannabis has been a booming industry in the USA and many other countries in the past decade. This followed a slow, but steady trend toward full legalization, even if doing so at the US federal level of what was formerly considered a drug might wait some more years.

Public acceptance is following, with support for legalizing cannabis hitting a record 88% and cannabis tax revenue at $20 billion, nearly double that of alcohol.

This has created a large market for legal cannabis cultivators, who usually leverage high-tech methods of cultivation, mixing greenhouses, vertical farming, advanced plant varieties, and high-performance extraction methods.

Investing In Cannabis

Still, despite its obvious popularity and increasing acceptance as a “mild” drug akin to tobacco or alcohol, investors often struggle to access cannabis stock. This is because as long as it is illegal at the federal level, most stock brokers and banks are not authorized or unwilling to trade the stocks producing and selling cannabis products.

This is a pity, as such “sin stocks”, involved in “immoral” activities, have historically generated superior investing performance, be it casinos, alcohol, tobacco, weapon manufacturing, etc.

However there might be an opportunity for investors to capitalize on the providers of the cannabis industry, which are not exposed to such restrictions. As a result, such a company can more easily raise money and be a viable investment from financial institutions like banks, investment funds, and pension funds.

One such company is Aurora Cannabis (ACB +0.66%), a biotech company specializing in cannabis.

The company, together with researchers at the nearby University of British Columbia (Canada), recently published a new discovery regarding cannabis plant mechanism for defense against fungal diseases¹ in the scientific journal Frontiers In Plant Sciences, under the title “Mapping and characterization of a novel powdery mildew resistance locus (PM2) in Cannabis sativa L.”.

Cannabis Cultivation

The cannabis plant, or marijuana, or Cannabis sativa L, is a plant rich in active compounds. While it is known mostly for its psychoactive effects, its complex biochemistry could also provide interesting chemicals for the treatment of depression, mental illnesses, and cancer.

It is also a plant requiring a very warm climate and abundant fertilizers for optimal growth and production of the desired chemical compounds.

So, cultivators have progressively moved from low-tech open-field cultivation in warm climates to advanced cultivation strategies in greenhouses or indoor farms. This is also a must for growers in US states that legalized cannabis, as inter-state trade of the plant is still strictly banned (as it falls under federal jurisdiction, where marijuana is still a restricted drug).

The problem with these cultivation methods is that the high-temperature, high-moisture, and very fertilized plants create the ideal conditions for contamination by pathogens, especially fungi. So even more than in open fields, keeping control of disease in most modern cannabis farms is a very important topic, one associated with a lot of potential financial losses.

While heavy use of pesticides can help, this is far from ideal for a product that will later be used by humans and could cause significant health issues and problems for the industry in the long term.

Plants’ Immune System

One of the most prevalent cannabis plant diseases is powdery mildew (PM), caused by a microscopic fungus called Golovinomyces ambrosiae. It results in premature leaf drop, poor flower quality, and significant yield losses.

Source: Frontiers In Plant Sciences

Plants have many mechanisms to protect themselves from diseases. Some are in-built defenses, like thick cell walls or always present biochemicals.

But some are more complex, reacting to the detection of a pathogen attacking the plant.

It is one such mechanism that has recently been discovered by Aurora Cannabis based on a genetic region of cannabis’ genome they named PM resistant locus (PM2).

Genes For Mildew Resistance

The researchers found that the genetic expression of PM2 induces the production of reactive oxygen species (ROS), very oxidative molecules that can stop the pathogen’s growth. It also blocks it from reproducing through spore production, reducing the risk of contamination of other plants.

They double-checked that this hypothesis was correct by observing the ROS production in a microscope.

Source: Frontiers In Plant Sciences

This gene cluster was found in two different variants of cannabis in a large genetic databank of the plant. They subsequently tested the plant, and confirmed that these “cultivars” of cannabis were resistant to powdery mildew.

Source: Frontiers In Plant Sciences

This resistance also proved to be “dominant”, meaning that only one copy of the gene was enough, making it a lot easier for plant breeders to create resistant varieties.

Improving Commercial Cultivars

Resistance to disease in some varieties of the plant is a good start. But often, these varieties are also less-than-desirable in other traits from a cultivator’s point of view: speed of growth, chemical composition, resistance to heat, drought, other diseases, etc.

In the past, this would have meant a long and tedious process, often taking years or even decades to hybridize the plant with the resistance to commercial cultivars so that the trait can be transferred without losing any of the other qualities of the commercial variant.

This is not true today, as genetic engineering has made great progress, opening the way for taking this gene and putting it directly into commercial plants.

Finding the Right Gene

To perform this feat of genetic engineering, the researchers need to find not just the part of a chromosome responsible for the resistance to mildew but the exact gene involved. So they created a complete map of this part of the plant genetics, completed with the likelihood of a specific gene being the one causing the resistance (blue bars below).

Source: Frontiers In Plant Sciences

So far, it is not yet clear if one specific gene is responsible for the resistance, or maybe a combination of 2-5 genes in this PM2 genetic cluster.

Still, this represents a major step in improving cannabis’s natural resistance to its most common disease.

“This discovery offers a critical solution to a pressing challenge in the cannabis industry worldwide.

Successful introgression of PM2-mediated resistance into elite cannabis cultivars will reduce the reliance on chemical pesticides, which are heavily regulated in cannabis as in most other crops.

Lana Culley – Vice President of Innovation and International Operations at Aurora.

Investing in the Cannabis Sector

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