Cannabis plants are sensitive to pathogens. Many cannabis growers suffer from crop failures due to diseases that destroy cannabis plants. A recent scientific breakthrough seems to change that.
Scientists have a purple-colored cannabis strain discovered that appears to combat the widespread plant disease Hop Latent Viroid (HLVd). HLVd damages cannabis plants and significantly lowers their value by reducing the amount of active compounds the plant produces.
Resistant cannabis plant
But two weeks ago, a group of scientists from Medicinal Genomics, a Massachusetts-based company, announced that they had accidentally discovered that one of their cannabis plants appears to be partially resistant to HLVd. The scientists also noted that the plant turned purple as it battled the disease.
Cannabis plants can occasionally change from green to other colors, such as red, blue, or purple, due to genetic or environmental factors. Purple plants have long been valued in the cannabis community, with prized strains such as Granddaddy Purple, Mendocino Purps, and Purple Haze.
Kevin McKernan, the chief science officer for Medicinal Genomics, announced his company's findings at a conference in Florida earlier this month. McKernan said the plant was significantly more purple than a second plant that had the same genetics but had not been exposed to the viroid. “We don't know why this is happening. This could be an immune response.”
Threat to cannabis growers
Zamir K. Punja, a Canadian professor of plant biology, said at the same conference that he sees HLVd as a major threat to cannabis farms. His research has shown that infected plants can reduce their THC yield by 40%, causing serious economic damage to a farm.
It is extremely difficult to get rid of the pathogen because HLVd spreads easily between plants, sticks to used materials and circulates in a cannabis farm's water supply. In addition, an infected plant is more susceptible to other diseases.
The good news is that HLVd does not pose any health risk to humans as it only affects plants. Punta added that there is evidence that some strains of cannabis are much more resistant to the effects of HLVd.
Super plant
McKernan said his company didn't initially realize they had a plant with a unique response to HLVd. The scientists deliberately infected plants with HLVd to try and understand how the disease changes infected plants. They rubbed the viroid directly onto cut leaves from the plant. What turned out? One of their specimens, a cannabis strain they call Jamaican Lion, was resistant.
The team repeatedly exposed the plant to HLVd for six weeks, but the plant never tested positive for the virus. In the end, the scientists injected the viroid directly into the plant's stem, but even then, the disease only appeared to infect the roots of the plant and not the leaves.
The team noticed that the infected plant's leaves and flowers turned purple, but a second uninfected version of the same plant did not change color. They continued to test the plant for HLVd, but 57 of 57 purple plant tissue tests came back negative. The only leaves to ever test positive for the virus were green leaves on The good news is that HLVd doesn't pose any health risk to humans because it only affects plants, Punja said. He added that there is evidence that some strains of cannabis are much more resistant to the effects of HLVd.
Anthocyanin
It's not clear why the purple plant material is associated with fighting the disease. McKernan attributed the color change to the "increased" production of anthocyanin, a plant compound that can turn cannabis purple. McKernan said it's worth investigating more purple plants to see if they are tolerant to HLVd, as anthocyanin production is already associated with fighting viroids.
McKernan added that his company is conducting new experiments on this particular plant to better understand how the variety fights HLVd. Cannabis farmers are currently battling HLVd with a combination of cleaning techniques and testing, hoping they can remove infected plants and reduce the spread. Will this new discovery save cannabis growers from crop failure?
Source: sfgate.com (EN)
