Interesting! Thanks for the tid-bit, Mamuang.
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Is there a (relatively) cheap Male Vs Female genetic test available for persimmons? It’ll be useful to save space now (and trying more females) rather than waiting for a few years. I know @Marta had a test for evaluating Yangmei seedlings.
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I would need to study the literature on the topic. I remember a paper from Luca Comai from a while ago on the sex determination in D. lotus. Every species is different and will require its own assay even if the data is available. I would think that maybe in Japan or China they did this work for kaki
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I’ve mentioned this guy in Belgium before but he’s doing some interesting stuff with Persimmon breeding. Heres his latest release, a PVNA with all perfect flowers.
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It is not known whether there is one or several different genes responsible for PCNA. The complete set of genes for D. kaki and D. virginiana are also not known, nor are there viable whole sequences of chromosomes available for them. The cost for a complete set of viable chromosome sequences per plant specimen is currently $ 7k. There are cheaper options but they are not high-accuracy and also contain many gaps.
I have read all the papers on this topic mentioned by members on GrowingFruit plus a few more recent publications. The methods being used are akin to several blind people touching a boulder to determine its shape and mineral content. Unfortunately that is the current state of technology with regard to gene identification.
Sorry to be a party pooper.
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I don’t disagree, but this seems a quibble to me. You are a party pooper, but IMO the party can rage on. . . .
I believe it is fair to say that:
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The J-PCNA trait is inherited in a way that is consistent with the hypothesis that there is a single gene that is recessive. So the J-PCNA trait behaves AS IF the J-PCNA variety has the same recessive allele on all 6 chromosomes.
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The C-PCNA trait is inherited in a way that is consistent with the hypothesis that there is a single gene that is dominant. So the C-PCNA variety behaves AS IF the C-PCNA variety has the dominant allele on at least 1 of the 6 chromosomes, maybe more.
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The PVNA trait is inherited in a way that is consistent with the hypothesis that there is a single gene that is neither dominant nor recessive but rather additive. So a PV variety behaves (i.e., is PVA or PVNA) AS IF the PV trait depends on how many of the 6 chromosomes have the PV allele. [Maybe there is not one but rather multiple copies of PV alleles on each chromosome – we can’t tell.]
So sure, the reality is that we haven’t proven the case beyond doubt. But this is hardly unusual in science. Most of what we take as “fact” is actually just “hypothesis.” For example, we all behave as if there is a thing called “gravity” even though we’ve never observed it. We’ve only observed its consequences. We behave as if gravity exists because that works.
I don’t see any reason not to accept as a provisional fact or strong working hypothesis that the PCNA trait is inherited as I describe. There have been LOTS of crosses of various PCA, PVA, PVNA, and PVNA varieties and, as far as I know, there is no contradictory evidence.
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We can observe gravity, not direct as in to measure the field, but we can measure the effects of gravity. This is not a very good example. I could say that we have never observed the sun, but we have observed its consequences in the same context. Personally, I’m convinced we are all part of a simulation being run on a universe size computer.
That hypothesis goes back to a statistical analysis based on breeding data when “gene” and “allele” were used to identify correlations and before the present day biological discipline of functional genomics began or any viable sequencing of DNA of any length existed.
Ditto.
In fact the case hasn’t been proven at all.
In my experience it is hardly unusual in horticultural genetics.
https://frostconcepts.org/
It’s ok to have questions that can’t be answered - R. Feynman.
No, it doesn’t. It follows from a simple logical analysis of the results of every cross of a PCNA variety. No statistics required!
Show me one example of a persimmon cross that produced results inconstant with my three statements above.
Well, basically you are agreeing with me. Richard is complaining that we have not identified the genes, not directly. I’m saying “so what?” – we have observed the effects of the genes in the patterns of inheritance.
@jrd51
I wasn’t referring to the persimmon literature, but rather the genetics literature as a whole.
This is in agreement with what I stated above.
I am done with this conversation.
You go to a casino and do you decide upon a machine having three rolls or do you choose a machine with 6 rolls or how about a machine with 9 rolls or ways to win. This is persimmons each time the handle is pulled. There’s 9 rolls and ways to win in diagonals or across or up and down or in the corners, etc- etc-
Everyone knows this now who’s been paying attention.
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Not quite a casino Dax. Technically, genetics makes the game much more complex. For example, you might make a cross of JT-02 with Taishu as per this thread which is a backcross to the parent. The result could be a PCNA with somewhat predictable frequency. However, nothing says the resulting PCNA tree would be cold tolerant. The combination of cold tolerance and PCNA fruit is an unknown genetic combination meaning that we have no idea if it can be made. There may be problems with linkage where the PCNA trait is tightly linked with D. kaki hardiness meaning it is not possible to get a true breeding PCNA that is also cold tolerant. I don’t “think” this is true, but it has to be considered when plant breeding with a hexaploid is contemplated and the inheritance pattern is not fully understood.
I’ll say this a different way by suggesting that a backcross could be made Taishu X JT-02 where the odds of all 6 chromosomes carrying PCNA are in the offspring. The odds of all 6 aligning are 1 in 4 or 25%. But then you have to consider that the cold hardiness might be lost meaning the actual number of trees that have to be grown to get a cold hardy PCNA is somewhere between 1 in 16 and 1 in 128. The reason is because we don’t know how many genes control cold hardiness. We also don’t know for sure that there is only one gene associated with PCNA.
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@Fusion_Power – I agree with all of this, almost. In particular, I agree that to get a good cultivar from a backcross of JT-02 x Taishu, we’d need to grow dozens or perhaps hundreds of trees. But at least one of those trees is likely to be NA, tasty, cold hardy etc. That’s why this kind of work is usually performed at a government-supported research facility rather than an amateur’s back yard.
My one quibble is with your estimate that “the odds all 6 aligning are 1 in 4.” Taishu will contribute 3 NA genes. Given that JT-02 has 3 NA genes and 3 A genes, the probability that JT-02 contributes 3 NA genes (selection without replacement) appears to be 3/6 x 2/5 x 1/4 = 6/120 = 5%.
Your point that the project demands a lot of new trees is absolutely correct. But it may be many more than you estimate. If we produce 100 hybrid trees, maybe (this is a probability not a certainty) 5 give or take will be NA. If we want trees that are NA and cold hardy and good tasting etc, we might find one within those 5. Or we might have to grow 500 hybrid trees to get ~25 NA offspring, one of which may meet our criteria.
Under best possible conditions, 25% could be PCNA, under worst conditions, 16 to 128 could be PCNA plus cold hardy. In the end, this is just a numbers game. In reality, as many seed would have to be made as it takes to get the combination desired. IMO, you are still an order of magnitude too low. I think it would take about 2000 seedlings to find one good tree that expresses PCNA and is cold hardy and has good quality fruit. The problem is that we are talking about “traits”, not genes. PCNA “may” be a single gene, or it may not. Cold hardiness is definitely NOT a single gene, it is a combination of multiple genes and multiple regulated biopaths. The same is true of fruit quality, it is a trait resulting from a large number of genes in multiple biopaths.
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@Fusion_power – Could you explain your calculation, more or less as I did. As you can see, I assumed that Taishu is homozygous for NA (6 NA genes) and JT-02 is 50-50% (3 NA genes, 3 A genes). Did you assume something different? Or is your arithmetic different? Why do you get 25% NA whereas I get 5%?
Please focus on the NA trait only.
Segregation in JT-02 - presuming this is normal segregation with no genetic quirks - produces the following oocytes in the following ratios. Keep in mind that Taishu is presumed to produce only one genotype for PCNA which is 3 PCNA. (Hexaploid is 6 sets of chromosomes in the fertilized cell)
PCNA = n and PCA = A where n is presumed recessive and A is presumed dominant. It doesn’t quite work this way, but it is what it is.
JT-O2 has this genome: hex(nA, nA, nA)
When it segregates, the result can be as follows:
1 - nnn
1 - nnA
1 - nAA
1 - nAn
1 - AAA
1 - AAn
1 - Ann
1 - AnA
A total of eight separate oocytes can be produced presumably with standard frequency. Now the quirk is that PCNA with 6 “n” genes will always express PCNA. But if you read the literature, you would have seen that 5 “n” genes will also express the PCNA phenotype. So this means that of the eight reproductive cells, four of them produce PCNA traits. They are “nnn”, “nnA”, “nAn”, and “Ann”. For similar reasons, there will be four genotypes that produce PCA phenotype, they are “AAA”, “nAA”, “AAn”, and “AnA”.
From this perspective, half of the offspring in a cross JT-02 X Taishu will express PCNA trait. Does this mean that 12.5% of the offspring would be pure PCNA? See if you can figure out where I am deliberately misleading in this! 
Remember that Taishu is presumed homozygous 6 PCNA!
I’m going to short circuit this a bit by stating that the math is NOT 3/6 X 2/5 X 1/4. It is 1/2 X 1/2 X 1/2.
For similar reasons, in a cross with two persimmons both of which are JPCNA X D. Virginiana (same as JT-02) then the math is 1/4 X 1/4 X 1/4. Genetics with a single trait is always binary, even in a hexaploid genome. When you get a non-binary result in single trait genetics - like 5% - immediately suspect a problem with the math.
Even with the above, genetics can still throw you for a loop. You might make the cross JT-02 X Taishu and produce 512 seedlings but none of them would be pure PCNA. You might also produce only 4 seedlings and voila, one of them would be pure PCNA. In the genetic ‘casino’, sometimes you get lucky, sometimes not.
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