More updates on viroids and cloning practices for minimizing or slowing down the spread over time.
In my quest of tying this whole dudding syndrome with viroids and trying to figure out best practices that we can use as growers to protect ourselves from the dudding phenomena and any future viroids that may arise in cannabis from the commercialization of the crop. I’ve reached out to Dr John Brunstein who is a PhD, and member of the MLO Editorial Advisory Board. He serves as President and Chief Science Officer for British Columbia-based PathoID, Inc., which provides consulting for development and validation of molecular assays.
I’ve gave him my observations that I’ve had regarding viroids and taking clones from moms versus clones from the tops of healthy looking veg plants that may also have the virus but have not developed any symptoms yet. Here is his answer which surprisingly suggests a treatment of bleach very similar to
@Wisher619 treatment described in my previous post. He has a new paper in the works dealing specifically with viruses and viroids in cannabis which addresses some of the issues stated.
Quick answer however is that in plants, lacking an active circulatory system like animals, intracellular pathogenic microorganisms (including bacteria, fungi, viruses, and viroids) don’t always transmit along to all cells in the plant, and may move cell to cell rather slowly via existing vascularization. One result of this is that if you have an infection at one place – say, an insect has vectored a pathogen onto a particular leaf – you’ll get a localized area of disease which slowly spreads. If you take a cutting from this diseased area and do vegetative propagation, you’ll get a plant with most – and eventually, almost all – cells infected. However, if you take a cutting from a distal portion of the plant, it has a better chance of still being pathogen free, and allowing for onward propagation of healthy material.
The extreme example of this is microdissecting off apical meristematic tissue, before it’s vascularized. While I hesitate to say this is absolutely guaranteed to be pathogen free (it’s possible shared cytoplasm or nucleoplasm from progenitor cells could include pathogens, much as e.g. mitochondria and chloroplasts are transmitted to mitotic progeny) it’s at least “highly likely” to be pathogen free. It’s also effectively pluripotent when treated with right growth factors, and hyperthermic treatment can be used to further increase likelihood of clearance of any residual pathogen(s). This is the basis for plant tissue culture.
So quick answer – yes, it’s not surprising that if you select just youngest tissue from incoming starter plants, you will at least some of the time rid the clone of pathogens carried in more mature distal tissue. It would be best to combine this with a surface cleansing (dilute bleach) to reduce external pathogens as well, and then move the material into a clean facility. It’s not guaranteed to to work all the time – if a pathogen has spread enough to be in cuttings you took, it’s still there – but it will work at least some of the time and is probably good practice.
Originally he had written this paper last month on genetic drift which caught my attention so I decided to reach out to him and ask him for his thoughts on why taking the tops of healthy veg plants had shielded me from the dudding syndrome until I started cloning from a mother olant.
"Genetic drift" is often used to describe change in appearance/behavior of a clone variety over time. However, this may not be the correct use of the term.
cannatechtoday.com
