I’ve got a great tasting heirloom apple that is well adapted to my climate, the hot and humid southern U.S. Speculation from some people is that it’s Paragon or Mammoth Blacktwig. Two questions. First, does anyone have any experience or an informed opinion about the usefulness of the testing provided by Washington State?
A description of the testing:
" DNA Fingerprinting: DNA fingerprinting using leaf samples, is available by request. We now use a Simple" test that will cost you $50 per sample. For each tree tested, this method uses a small amount of leaf tissue and determines identity vs. uniqueness (in other words, whether the tested tree is identical to a cultivar already in our dataset), and is best suited for any tree suspected to be a cultivar and not a one-off seedling. Sometimes it can also identify parents, but it’s streamlined for identity-checking."
Second question: Does anyone have any experience with the Paragon apple? I know there is some debate and confusion between it and Mammoth Blacktwig.
Recently it has been discovered that many of the markers used for genetic fingerprinting are not in the cell DNA. We do not know why the assay method (PCR) returns positive responses in these cases. I’m checking with WSU to determine their assay approach.
I sent them two emails to them around the first of this month asking them about this program. I have yet to hear anything from them. So far not impressed.
I believe that UC Davis does pcr testing also, but my recollection is that it’s expensive and does not guarantee an exact match.
@Charles
There are many sources for PCR assay, both academic and commercial. They differ by in-house catalogs of fingerprints. Here is the page for UC Davis:
Too rich for my blood to have apples tested, $410. 
@MikeC
I’m with you.
I wouldn’t pay 1¢ for PCR-based identification or ancestry testing of my plants.
SNP would be a different story, depending on device.
I sent two fresh leaf samples to WSU DNA lab last April. They sent me word about my two apple trees on February 4. $50.00 each.
Yep, both had been mislabeled: one a seedling with no precedent in the data base & the other, Twenty Ounce.
I just received my report from the WSU DNA lab as well. I sent my samples to them back in late April last year. I thought they had forgotten about my sample or it had been lost in processing. Mine was mislabeled as well. It was supposed to have been a RI Greening- not even close…it came back as Tolman Sweet.
Perhaps. It is equally likely that the scoring method use to create the profiles in their database is incorrect.
Such as? Who’s database? The orchard we bought them from or the lab where we had the DNA testing from?
I have no quarrel with the results. The seedling resembles nothing I have had experience with, nor the good folks at Temperate Orchard Conservancy, who checked the fruit a couple years ago.
As to the Twenty Ounce, I have experience with that cultivar from two sources & can verify the DNA test when it sets debut fruit.
@NuttingBumpus
Horticultural PCR is not a “DNA test”. They do not look at the contents of the protein extracted in the chain reaction. It is a bill of goods sold to the USDA by equipment manufacturers.
Does that then differ from the “DNA tests” humans pay to have performed for genealogical research? Or is human vs fruit tree DNA “apples to oranges” so to speak?
Yes. PCR tests use a pair of “markers” to chemically extract relatively short protein sequences. In horticultural PCR, the molecular weight of the extract is obtained within reasonable accuracy. This weight is then used to estimate the length of the segment. The contents are not examined. For two decades now, DNA experts have been referring to this approach as “phrenology”.
Further, PCR tests of celled organisms in general are designed to determine dissimilarities – not similarities. If two specimens have the same PCR “profile” (marker responses), DNA experts consider them outside the range of marker resolution.
Sometimes. Human DNA is diploid. So are several fruits, e.g. common fig. Each chromosome is formed by two interconnected strands of protein molecules, and there is only one copy of each chromosome in each cell nucleus.
Non-dipoid DNA is termed polyploid. American persimmon (D. virginiana) is an example. But so are Pippin apples. So in that case, comparing “Delicious” to “Pippin” is like comparing “apples to oranges”!
Note that PCR is designed for diploid organisms. Using it on polyploids is a wishful, erroneous activity.
Also more likely someone got right & left turned around, or the like, while grafting or sorting. I got a whip from a very reputable outfit some years ago which was clearly mislaid/misidentified.
It turned into a good thing for me, for I began looking up alternative names for what I had & learned about Twenty Ounce. It was not 20 Oz., but through another happenstance Twenty Ounce is now growing in my yard & I am excited for that.
What apples were they supposed to be vs what they actually ended up being? I know you said one was actually a 20oz apple.
One scion from the jar marked “Twenty Ounce” turned out to be a seedling, with Fameuse/Snow a likely parent. (At WSU DNA lab it is labeled Something Else.)
The other scion, from a jar marked “Orleans Reinette” turned out to be Twenty Ounce. (I’ve asked the two fellows I know involved in that scion swap for the likely donor & neither has these varieties nor knows who might have brought them.)
Something Else has a lovely pink bloom and very round, solid fruit of moderate size. The tree is as upright as Maiden Blush, but more precocious & fruitful so far. Tree & fruit are spotless amidst the rather light disease & bug pressure here. I covered its fruit with orchard sox with commendable results. Its bloom is rather late. (It is too close to the sewer drain from the house so I will take scions from it before digging it out altogether.)
Twenty Ounce bloomed first time last year, but did not set a single apple. Maybe this year. BTW, I have had Twenty Ounce from two organic orchards 50 - 90 miles away. From one they had amped apple flavor, no overtones; heavily striped over green/gold. From the other, they had very light mint overtone, apple flavor was the more usual degree; nearly solid red on red.
My experience with scion swaps is that people wander around and grab scions self-serve style. I’ll bet most of the mix ups happened from people grabbing a scion, changing their mind and then putting it back in the wrong cup. Probably would be best if people did these exchanges more cafeteria style with someone “manning” each table to oversee distribution and prevent mix ups.