I like them because they are simple to eat. I don’t have to worry about them being adequately pollinated, wait for them to adequately soften, or artificially remove astringency. Like Dax, the added hardiness is important for me, because my growing zone is marginal for growing most pure kaki. Perhaps just being 25% American is enough to change the flavor for the better while being PCNA, which would be the case if JT-02 is crossed to a PCNA male. Recall that Nikita’s Gift is 75% kaki and 25% virginiana, yet has a much richer taste than a typical kaki.
In regards to backcrossing to a PVNA male, I did just that with JT-02 x Nishimura Wase. The fruit will be seeded with luck. I like Nishimura Wase because the fruit is large and early ripening. These are 2 additionally important traits to me.
PCNA is based on a single gene. So long as all 6 copies are of the PCNA variant, it should be PCNA. In theory, cold hardy from D. virginiana and large non-astringent fruit from D. kaki should be feasible.
@Harbin – the genes for NA move independently of the other genes.
With the requisite number of crosses, we can produce a hybrid that has 100% (i.e., 6) NA genes but still 50% of more genes from Virginiana for hardiness.
That’s not how genetics work. Persimmon has a base 1N = 15 chromosome count. Since kaki and virginiana are hexaploid, they have 6 X 15 = 90 chromosomes. The gene for PCNA is on one of the chromosomes out of 15 in a base set. The other 14 chromosomes in all 6 copies could be pure virginiana leaving only the chromosome with PCNA from kaki. However, there are other desirable genes in kaki such as the genes for fruit size. I expect we will eventually have fully hardy large fruited hybrids that are PCNA. There is nothing at this point that would preclude the possibility.
@Harbin – If you mean that the genetics as described above by @Fusion_power are mere theory, you’re wrong. If you mean that the genes for characteristics such as fruit size, flavor, cold hardiness, splitting are inseparable from the gene for NA, you are wrong.
The only reason we don’t have a PCNA hybrid is that nobody has back-crossed JT-02 to Taishu.
If anyone locates a Taishu tree and can get pollen from it, I, as well as several others I assume, will be happy to hand pollinate.
I’ve stored pollen from kiwifruit for a couple of years in the freezer and have had it still be effective afterwards. I assume persimmon pollen isn’t that different.
Since no one has ever produced a homozygous PCNA D. virginiana, it is still not known if these genes will remove astringency in a virginiana background. There are known differences in how astringency behaves in kaki vs. virginiana. Ethanol or CO2 treatment works in kaki, but not in virginiana. It is a possibility that PCNA genes will also fail to remove astringency in virginiana. There are way too many unknowns to know for sure until it is tested. It is certainly worth pursuing, but definitely not guaranteed to work.
I would still expect it to work in hybrids with more kaki than virginiana, and we are a very long way away from a predominantly virginiana homozygous for PCNA without resorting to genetic modification.
I’d agree with your 1st paragraph – We can’t be absolutely sure that a DV tree that is homozygous for the Asian PCNA gene (through, say, direct genetic manipulation) would be non-astringent.
On the other hand, if we back-cross JT-02 x Taishu then the offspring will be ~75% Kaki. It seems likely (not inevitable) that the Asian PCNA genes will interact appropriately with other Asian genes to produce a NA fruit. This may not happen in ALL homozygous offspring, but it seems likely to happen in a subset.
I disagree with the implication of your 2nd paragraph. We are literally 1 back-cross away from a hybrid that is homozygous for PCNA. WE DON’T NEED THAT HYBRID TO BE “PREDOMINANTLY VIRGINIANA.” All we really need to retain from the DV ancestor is some cold hardiness and maybe some flavor. The primary goal, after all, is not to make DV non-astringent. It is to make Kaki cold-hardy. The secondary goal is to add some DV flavor to the PCNA Kakis.
A successful NA from the backcross would likely lead to continued crossing back into DV or hybrids to get more variety, which is fine as long as it works. With enough seedlings, you should be able to get a cold hardy hybrid with DV like flavor. The real question is how many seedlings? If just one single different genetic locus exists in DV that can override the effects of the PCNA gene, then the odds go way down. Instead of 1/16 NA female seedlings from your backcross, you would now be looking at 1/256. If I was trying to breed a NA hybrid, I would really try to get my hands on a dominant NA kaki as insurance. There is no guarantee that a dominant NA will work either, but at least you will find out with just a few seedlings.
We still got Luo Tian Tian Shi to hybridize with. It (forgive my ignorance) carries something such as 5 of 6 of the genes (possible) for cold-hardiness. It’s late-ripening, but it’s very special I believe for producing a hybrid PCNA.
@Barkslip – The gene in the Chinese PCNAs appears to be dominant. You are right to imply that the most direct route to a PCNA hybrid would be a cross between a Chinese PCNA and an American. HOWEVER it seems likely the initial cross between the Chinese Kaki and any Virginiana would be very difficult, requiring special techniques beyond the capabilities of normal humans. On the other hand, JT-02 [already a product of embryo rescue] would probably respond to pollination by Taishu by producing viable seed. So you or I or @ramv could perform the hybridization, produce the fruit, grow the seeds, etc. ourselves!
Can somebody supply more information? By “hybrid” I understand Kaki x Virginiana. Which hybrids are PCNA or PVNA?
When I use the term “PCNA hybrid” I DO NOT mean a hybridization that includes a PCNA parent. Ho Hum. I mean a hybridization that results in a PCNA offspring. Said as clearly as I can, the offspring is a Kaki x Virginiana hybrid that is itself non-astringent.
Here:
I have every intention of putting it near several pollinator hybrids like Universal, Nikita’s daughter, Rosseyanka’s male mutation (who is a true original F1 as well) … to see what will come out of it.
When to taste … there is something for everyone. And who has said that this fruit is not good.
All the descendants are of excellent quality.
