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What is Hop Latent Viroid?

What it’s not… good. It’s not a good thing when it comes to our cannabis plants. Hop Latent Viroid, or HLVd, is a pathogenic viroid that affects hop plants (hops are used to produce beer). Since it’s a more recent discovery, we are still trying to understand the cause of it and how to prevent it. For now, to answer what is Hop Latent Viroid, we are diving deep into the research that has been done.

Hop Latent Viroid… What is it?

Now that you know it isn’t a good thing, let’s find out why. Viroids are small, circular RNA molecules that can infect plants and cause diseases. HLVd has been common in targeting hop plants and can cause symptoms like stunted growth, yellow leaves, and reduced production. One thing is for sure, it does not pose a risk to our health. 
One huge concern with HLVd in cannabis is its potential to negatively influence the quality of the flower it produces. Studies have shown that HLVd-infected cannabis plants can possibly have an altered cannabinoid and terpene profile.

How does HLVd spread?

How does HLVd spread?

HLVd is mostly transmitted through the infected parts of a plant, like cuttings or seedlings. However, it's alarming how easily it can also be spread through things like pruning tools or machinery. Once a plant is infected, the viroid can spread within the plant and to other plants around it, underscoring the need for strict preventive measures. 

There are a few ways that an infected plant can transmit the viroid to other plants. 

Plant-to-plant transmission: When a healthy plant comes into direct contact with an HLVd-infected plant. This can be done with physical contact with leaves, stems, or roots or through the exchange of plant fluids. 

Mechanical transmission: As mentioned above, tools, machinery, or any equipment used when cultivating the cannabis plant can spread HLVd. If any one of these mechanics is contaminated with HLVd-infected plant material, it can possibly spread the viroid to healthy plants. 
Seed transmission: While this is less common, there is evidence suggesting that HLVd can be spread through infected seeds. If the seeds of a cannabis plant are infected, the viroid can be spread and passed on to the next generation of plants.

How plant cell technology can help rid HLVd from cannabis

How plant cell technology can help rid HLVd from cannabis

There is so much value when utilizing technology in situations like an HLVd-infected plant. There are three studied and tested ways that show the positive effects of plant cell technology. 

In vitro propagation: Plant cell culture techniques, such as tissue culture or micropropagation, can be used to produce disease-free cannabis plants. This process starts with clean, HLVd-free plant material and produces a new stock of healthy plants. 

Meristem culture: Meristems are the actively dividing regions of plant tissues, and they are often free from pathogens like HLVd. Keeping these meristems in a sterile environment will in turn, generate virus-free cannabis plants. 

Genetic transformations: there are biotechnology techniques like genetic engineering. Studies show that this method has the potential to develop cannabis plants that are resistant to HLVd. 

Hydroponic systems and HLVd prevention

Growing cannabis without using soil isn’t a new thing. It is, however, a more advanced method used in producing healthy marijuana. Hydroponic systems offer several benefits, let’s check ‘em out.

Disease-free growing medium: Using inert growing mediums like rockwool, coco coir, or perlite. These are all free from soil-borne pathogens, like viroids, with the help of their non-porous structure. 

Enhanced disease monitoring and control: Using a hydroponic system provides a more controlled environment that is easier to monitor for infections, diseases, and bacteria. This is perfect for getting early detection of a problem before it spreads. 

Reduced risk of soil contamination: Viroids love soil and thrive for extended periods of time. When soil is completely eliminated from the equation, viroids don’t stand a chance in hydroponic systems. 
Better growing conditions: Having more control on things like temperature, humidity, and lighting will promote vigorous plant growth. This gives us strong and healthy cannabis plants that are generally more resistant to diseases.

Controlling Hop Latent Viroids in Cannabis Plants

Controlling Hop Latent Viroids in Cannabis Plants

Growers can take a few different measures to control Hop Latent Viroids in cannabis plants. The main goal is to prevent the viroid from forming, spreading, and negatively impacting a crop, which can be done by the following. 

Start with a disease-free plant: As previously mentioned, the safest measure is to start with a certified disease-free batch of seeds. 

Regular inspection: Growers can regularly inspect cannabis plants for any symptoms of HLVd. Again, these are things like yellowing leaves, stunted growth, and less flower production. When growers know what symptoms to look out for, early detection can stop any HLVd-infected plants from spreading. 

Isolating infected plants: Just like your toxic ex, growers will immediately remove the toxic, infectious plant before it spreads viroids to the whole crop. 

Sanitation and hygiene: Since HLVd spreads so easily onto healthy plants, cross-contamination through machinery and tools is very possible. Growers can disinfect and regularly clean the tools, equipment, and surfaces that each cannabis plant comes in contact with. 
Genetic resistance: More recently, growers have explored the possibility of using cannabis varieties or cultivars that demonstrate resistance to HLVd. Breeding programs and genetic selection can help develop plants that are more immune to the viroid.

Cytopathic effects of HLVd

Cytopathic effects of HLVd

Researchers and scientists are still in the process of studying the pharmacokinetics and chemical structure of cannabis compounds (cannabinoids, terpenes, etc.) when infected with HLVd. Viroids also have the potential to influence the biosynthesis of various plant compounds found in cannabis. Even though specific mechanisms and consequences of HLVd infection on the chemical makeup of cannabis aren’t certain, we have high hopes!

While we are aware of the physical symptoms, yellow leaves, stunted growth, and smaller yield, there are a couple of “behind-the-scenes” symptoms coming to the surface. Since viroids are generally small, single-stranded RNA molecules, they can easily interfere with cellular processes and gene expressions in cannabis plants. Here are a few more microscopic disease symptoms of HLVd in cannabis plants.

Cell necrosis: Viroids can cause cell death or necrosis in the infected tissues of the plant. This results in dead or damaged cells that, when viewed under a microscope have brown or discolored areas. 

Plasmodesmata alterations: Plasmodesmata are the microscopic channels that connect plant cells and allow for the transport of nutrients, water, and signaling molecules. Viroids have the ability to affect the function and structure of plasmodesmata. This has the potential to disrupt cell communication and nutrient transport between cells.

Changes in organelles: Taking you back to middle school science… what’s the powerhouse of the cell? The mitochondria! Sadly, HLVd infections can lead to alterations in cellular organelles, like the mitochondria and chloroplasts. These changes can impact the normal functioning of these organelles, ultimately affecting the photosynthesis or energy production in the plant.