THE Hop latent viroid (HLVd), a viroid found worldwide in hops but which in recent years has spread to cannabis, continues to threaten crops.
SFGate, however, reports that scientists from Medical Genomicsa Massachusetts-based company, observed a cannabis strain, Jamaican Lion, which appears to be partially resistant to HLVd and turns purple when fighting the viroid.
Kevin McKernan, scientific director of Medical Genomicspresented the study “ Hop Latent Viroid Shares a 19 Nucleotide Sequence with Cannabis sativa COG7 at the CannMed23 conference in Florida.
The Jamaican Lion strain was thus found to be resistant to the viroid and turned more purple as it fought against the viroid. Jamaican Lion is a CBD-rich strain.
“We don’t know why [cela se produit]. It could be an immune response, but we don’t see this [coloration violette] also strongly increase in the uninfected control,” McKernan said.
Viroids can spread biologically or be transmitted by growers through hands or tools. Sterilization using a 10% bleach solution can reduce infection.
The scientists rubbed the viroid directly on the cut leaves of the plant to infect them, then they injected the viroid into a plant. Six weeks later, the plant variety was still not infected after repeating the test 57 times. While the researchers were able to detect HLVd in the plant’s roots, leaf and flower tissues tested negative until harvest time.
This is Jamaican Lion 10 weeks into flowering. 2 weeks past Harvest time (8 weeks of flower). It flowered all last summer. Was reverted to Veg in the fall. Failed to pick up HpLVd infection with several attempts at inoculating cuts with viroid. pic.twitter.com/ik8TUGza2m
— Kevin McKernan (@Kevin_McKernan) April 5, 2023
Effects of HLVd viroid on plants
HLVd results in smaller flowers and significantly less THC. Viewed under an electron microscope, mature trichomes—where most of the THC is found—look like a deflated balloon instead of ball-shaped. A study shows that 90% of Californian cannabis is infected with HLVd and that yield losses could reach $4 billion. While the viroid is bad news for cannabis, viroids only infect plants and therefore pose no physical danger to humans.
The reason why the plant resisted the viroid is not yet clear. McKernan explained that she turned purple due to increased production of anthocyanin, a chemical that can turn plants purple. The team believes that scientists should investigate whether there are more HLVd-resistant purple plants, since anthocyanin production is already linked to viroid control.
“There are studies linking anthocyanin production to viroid infection. It relates to different plants and different viroids, but these anthocyanins are a known plant immune response,” McKernan told SFGate.
Zamir K. Punja told the conference that HLVd should be considered a “major threat” to cannabis farms. Punja calls HLVd the “COVID of the cannabis world”. The results suggest that THC yields from infected plants can drop by up to 40%.
The long term solution to Medical Genomics in the fight against HLVd is to help breeders develop resistant cultivars – perhaps purple varieties – that do not suffer loss of yield or potency.
