Targeted Virus Screen, Hop

Targeted Virus Screening starts with RNA from the plant tissue that is being tested, which contains both the plant’s native RNA and RNA from any other organism that was in the plant (including pathogens like viruses, viroids, or phytoplasma). This RNA is reverse-transcribed (“RT”-PCR) to generate DNA, which can then be used in a reaction called Polymerase Chain Reaction (PCR). PCR amplifies specific, targeted segments of the DNA so that there is enough to be able to detect it – in this case, we target sequences that are specific to the pathogens of interest, so that we detect a signal only if the pest of interest is present in the sample. Different pathogens can be detected separately by either using fluorescent tags  of different color (in qPCR) or by qualitatively measuring the amplification.

Comprehensive Virus Screening tests for all 2,500+ known plant pathogenic viruses, plus other common pathogens, and is the most sensitive detection method available. It is most useful for testing mother plants, new varieties, and pooled blocks of crops, or when you believe there is a complex or unknown infection in the crop.

Targeted Virus Screen is a more economical option to test for the diseases most commonly found in the crop of interest. We offer panels curated for cherry, pome (apple and pear), or hop.

This is most useful in cases where you see symptoms in the field and have narrowed down the cause to one or a small number of viruses.

Decreasing costs through pooling: A great way to reduce the overall cost of testing many samples is to combine several plant samples together in the same test. For example, it’s common to test 5 trees together. If the pool is clean, then you know all 5 trees are virus free. If the pool is infected with a virus, you can either consider all the trees to be infected, or you can follow up with additional testing to determine which tree(s) caused the positive hit.

Possible strategies to consider:

1)Testing Individually is recommended for most applications with Targeted Virus Screening.

2)Pooling is recommended if you are testing many plants and it would be cost-prohibitive to test individually. We recommend pooling 5 plants per pool, but you have as few as 2 or as many as 10 plants in the same pool. The more plants per pool, the less sensitive the test – but even with 10 plants in a pool, Targeted  Virus Screening is still significantly more sensitive than protein-based assays like Elisa.

How to pay through our online payment platform and submit pooling information: When you check out online, you are ordering the number of tests you want to run – not necessarily the number of plants/samples you want tested. If you want to test 20 plants in pools of 5 plants each, that means you want to request 4 pooled tests – so you would check out and pay for 4 tests. We will provide you with a sample submission form, where you can list all the samples  and how they should be pooled.

Feel free to contact us – we are happy to help set up a sampling plan that will address the concerns you have.

We will contact you with sample preparation and shipping information after the test is ordered, but here are some pointers to get you started:

When to test: The best time to detect viruses is when they are actively replicating in the plant – and this can vary based on the virus you are targeting! A good rule of thumb is that June-August is the best time to test for most diseases, including testing for the viruses and phytoplasma that cause Little Cherry Disease.

Harvesting and Submitting Samples: Plan to use clean pruners for each separate tree/plant, and keep material from each plant separate in its own bag, even if samples are being pooled for testing. Provide 6” of stem/branch and 3-5 mature leaves for each plant. Keep all material cold, and ship as soon as possible via overnight courier.

Strawberry Reference Varieties

What’s the turn-around-time?

We do all sample prep, testing, and analysis in house, so we can usually provide results in 2 weeks.

What if you don’t test for the virus that I’m interested in testing for?

We offer Comprehensive Virus Screening, which includes all plant pathogenic viruses. You can also Contact Us and let us know – we want to know what’s most important to you.