Catching a hidden plant pathogen early.
We are developing molecular detection of hop latent viroid (HLVd), a pathogen that can move through a grow long before it shows.
A pathogen that hides
Hop latent viroid can reduce the quality of a harvest, and infected plants often look healthy.
Smaller than a virus
A viroid is a tiny circular strand of RNA with no protein coat. It is far too small to see, and it does not need to show symptoms to spread.
Costly when it shows
Infected plants can grow stunted, lose vigor, and produce smaller flowers with lower potency.
Spread by propagation
It travels with cuttings taken from an infected plant and on tools that touch one, so a single plant can pass it on to many.
Roots first, then the whole plant
It gets in
Through a cutting from an infected plant, or a tool that has touched one.
It reaches the roots first
The roots are usually where the viroid shows up first.
It spreads through the plant
Over several weeks it moves into the stems and leaves, often with no visible sign.
That is why roots are often the best tissue for early detection.
Detection at the molecular level
Our method uses reverse transcription quantitative PCR (RT-qPCR): RNA from the plant tissue is converted to DNA and amplified, and the signal is read in real time, cycle by cycle.
Root, stem and leaf
Being developed for root, stem and leaf, from both soil and hydroponic grows, with root tissue preferred for early screening.
A control in every reaction
Each reaction looks for the viroid and for a gene of the plant itself, confirming the tissue was extracted and the reaction ran.
Read by shape and timing
A result is judged by the shape of each amplification curve as well as the cycle at which it rises, not by a single number.
How growers clean up
No spray or chemical cures an infected plant. Growers manage HLVd by keeping it out and starting clean:
Test, then remove
Test parent plants, and young plants once they have roots. Confirm a positive, then take that plant out before more cuttings are taken from it.
Rebuild through tissue culture
To save valuable genetics, a new plant can be grown from the tiny growing tip of a shoot, sometimes combined with heat treatment. Results vary by variety, so plants that come out of culture should be retested over time.
Disinfect tools and surfaces
Clean cutting tools between plants, and the surfaces they touch, with a disinfectant shown to inactivate the viroid, such as bleach. Alcohol, the usual choice, does not.
Start from tested stock
Bring in plants from tested sources, keep new arrivals apart, and test them before they join the rest.
Clean stock starts with knowing
Growers often build their crops from a few parent plants. When one of them carries the viroid, its cuttings can carry it too, and the loss can show up later in the harvest. Our goal is a test that finds the viroid early, in the plants that matter most, so growers can act before it spreads.
Research project. Not offered as a test, and not covered by our ISO/IEC 17025:2017 accreditation (PJLA Testing #118890).