How to test for Hop latent viroid: root or leaf tissue?

Testing methods for Hop latent viroid (HLVd) in cannabis plants can be controversial, but research by TUMI Genomics and other industry professionals have identified root tissue as the most reliable source for detection.

So you’ve started testing your cannabis plants for Hop latent viroid, but what’s the best way to do it? 

There’s controversy in the cannabis industry about the most accurate and proven method for testing cannabis plants for HLVd. At TUMI Genomics, we’ve conducted and collaborated in multiple studies to identify which part of the cannabis plant, and at which growth stage, HLVd can most accurately and consistently be identified. We concluded that HLVd is most concentrated in the root tissue.

For experiment details, read our whitepaper, "Hop Latent Viroid Levels and Distribution in Cannabis Plant Tissue."

Highlights from Whitepaper:

1. Among the individual samples taken from the test plants, upper foliage samples showed variable success in the detection of HLVd (Table 1). 

2. Petiole taken from new growth showed between 10% to 100% success depending on the plant with an average success rate of 36%.

3. Old growth and tissue from freshly cut clones showed slightly better detection success with an average of 75% and 61% testing positive for HLVd, respectively. 

4. Every root tissue sample taken from either the upper or lower portion of the root ball of an infected plant showed robust amplification of HLVd, with 100% of samples testing positive.

Conclusion: Upper root tissue shows higher, less variable levels of HLVd. The 100% detection rate of Hop latent viroid in every root sample assayed indicates that the inclusion of root tissue when testing for HLVd can improve the identification of true positive plants.

A Few Supporting Studies

The study, "Emerging Diseases of Cannabis sativa and Sustainable Management," points out that advanced diagnostic techniques, like root tissue testing, are crucial for managing diseases such as HLVd. Integrating these methods into sustainable management practices ensures the long-term health and productivity of cannabis crops.

Punja ZK. Emerging diseases of Cannabis sativa and sustainable management. Pest Manag Sci. 2021 Sep;77(9):3857-3870. doi: 10.1002/ps.6307. Epub 2021 Feb 27. PMID: 33527549; PMCID: PMC8451794.

The study, “New Insights into Hop Latent Viroid Detection, Infectivity, Host Range, and Transmission,” introduces the concept of testing plants at different stages and with different tissues. This study measured the distribution and movement of HLVd in infected hemp plants over time. Within the first 3 days, HLVd spreads to adjacent tissues, reaches the roots by day 7, and moves to the upper leaves after 14 days, following a common systemic route. Notably, plants testing positive in the leaves also tested positive in the roots, with only one plant inoculated using RNA whose roots and not leaves tested positive for HLVd.

Atallah OO, Yassin SM, Verchot J. New Insights into Hop Latent Viroid Detection, Infectivity, Host Range, and Transmission. Viruses. 2023 Dec 23;16(1):30. doi: 10.3390/v16010030. PMID: 38257731; PMCID: PMC10819085.

Signs of an Inaccurate Research Study

When reviewing research studies or papers for information, it's crucial to be aware of several red flags that can indicate potential issues with the credibility, quality, or integrity of the research. Here are some common red flags to watch out for:

1. Lack of Peer Review: The study has not been peer-reviewed or published in a reputable scientific journal. Peer review helps ensure the validity and reliability of the research.

2. Author Conflicts of Interest: The authors have potential conflicts of interest, such as financial ties to the study's outcome,  citing their own previous work, or inappropriate funding sources. These conflicts can bias the study’s findings.

3. Unclear Methodology: The methodology is not clearly described, is poorly designed, or uses an inadequately sized or narrow sample group. Clear and well-designed methodologies are crucial for reproducibility and validity.

4. Lack of Statistical Significance: The study reports results that are not statistically significant or the study is missing traditional validation metrics. Statistically insignificant results may indicate that the findings could be due to chance rather than a real effect. Or that the experiment results have been manipulated or falsified.

Do Your Research

Regulation for cannabis cultivation is underdeveloped, especially for cannabis pathogen testing. This leaves room for misguiding information that can impact your sanitation precautions. So, you must advocate for your cannabis cultivation practices and understand which information is useful and which can be harmful to cultivation goals.

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About TUMI Genomics

TUMI Genomics is advancing cannabis cultivation by bringing biological insights to help commercial growers thrive. Through comprehensive preventative solutions, superior pathogen diagnostics, and AI-driven insights, TUMI Genomics is helping cultivators start clean and stay clean. The unrivaled diagnostics, transparent validation and industry-leading pathogen detection innovations provided by TUMI Genomics are raising the standards of commercial cannabis cultivation. The team at TUMI Genomics is composed of deeply experienced Ph.D. molecular biologists, bioinformaticians, business strategists, and accomplished serial entrepreneurs.

Media Contact: Hailey Spencer, Marketing Director

hailey@tumigenomics.com

Research Inquiries: Tassa Saldi, Ph.D., Co-Founder and CSO

tassa@tumigenomics.com