How a Clean Stock Program Can Help Prevent Viroid Spread in Cannabis
May 27, 2021 
Photo: Cannabis Training Institute
Front Range Biosciences (FRB), a cannabis and hemp genetics platform company, has released the results of a case study demonstrating the effectiveness of using tissue culture as part of a Clean Stock program to clean plants infected with Hop Latent Viroid (HLVd), ensuring a stable and consistent supply of healthy, disease-free plants for cannabis cultivation.
The year-long effort validates the utility of using tissue culture to effectively clean plants infected with HLVd and mitigate the risk of HLVd infection from spreading, guaranteeing clean, viroid-free plant stock for propagation.
HLVd represents the most challenging pathogen to face cannabis growers yet, already causing tens of millions of dollars in losses annually. The study demonstrates that a Clean Stock program leveraging tissue culture can mitigate the risk of costly cannabis crop failure, representing a huge win for the entire industry.
HLVd can spread asymptomatically and is hard to identify, allowing it to enter a production system and spread undetected. Once symptoms do show, the effects are often devastating. HLVd reduces crop yields by causing stunted growth, deformed leaves, and smaller, sparser flowers with fewer trichomes. According to MJBizDaily, California operators have lost 10% to 30% of their crop from the disease, and internal data shows infected plants can also suffer up to a 35% loss in cannabinoid content such as THC, and up to 70% reduction in yield.
The virus mostly spreads through mechanical transmission, such as using shared tools between infected and uninfected plants. With asymptomatic phenotypes, the lack of available molecular testing, and the fact that seed can have an infection rate up to 8%, the disease has the potential to impact the cannabis industry for many years and result in significant supply chain disruptions.
In FRB’s research, combinations of thermotherapy and meristem culture were used to treat six HLVd-infected Cannabis sativa varieties with positive HLVd status. All six varieties were shown to be HLVd-negative status after treatment and validated multiple times using an internally developed and validated molecular assay. These methods have been used successfully in other crops to solve viral pathogen challenges but optimizing and validating the process for cleaning up HLVd in cannabis, combined with FRB’s Clean Stock program for cannabis and hemp, demonstrates the effectiveness of a tissue culture program as a complete solution for viral pathogen mitigation in Cannabis sativa. FRB’s Clean Stock program includes redundant pathogen testing, micropropagation, true-to-type testing, and maintaining an elite mother stock for propagation. This validation provides FRB with a new set of tools to create disease-free germplasm using in vitro techniques.
“Hop Latent Viroid has become the biggest economic danger to cannabis producers on the West Coast and appears to be widespread throughout the hemp and cannabis industries. With no effective ways to treat HLVd in cannabis plants and testing not widely available, the FRB team knew this was an important challenge to tackle for the future of the industry,” says Dr. Jonathan Vaught, Co-Founder and CEO of Front Range Biosciences. :We’re pleased with the success of this study proving the economic value of using in vitro testing and tissue culture for long-term pathogen prevention and crop loss mitigation.”
Other agricultural crops such as strawberries, sweet potato, vines, raspberry bushes, and banana trees have experienced declines in quality and disease resistance after several generations of plants reproduced through cloning. While tissue culture and clean stock programs have been critical for horticulture and agricultural supply chain stability across a wide range of crops, FRB’s Clean Stock program introduces this process specifically for the cannabis plant.
“We have seen how other high-value crops have been impacted when varieties aren’t properly cataloged and testing protocols aren’t followed,” says Cecilia Zapata, Vice President of Tissue Culture and Technical Services at Front Range Biosciences. “The same techniques used to ensure the survival of those valuable crops can now be used to mitigate the risk for cannabis operators so they can stabilize the agricultural supply chain, scale the industry, and have the security of continued profits.”
To learn more about Hop Latent Viroid and mitigation techniques such as Clean Stock, visit www.frontrangebio.com. And check out this latest announcement on AgriScience Labs and CERESLabs licensing hop latent viroid detection assays from Front Range Biosciences and launch commercial testing services in Colorado and California.
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