Chinese PCNA X DV should be able to stabilize a cold tolerant large fruited PCNA in 3 generations. Because it is a dominant trait, this would be relatively easy to achieve.
American NA (Morris Burton or similar) should be able to stabilize a large fruited DV X DK with NA trait in 5 or 6 generations.
Japanese PCNA X DV should be able to stabilize a cold tolerant large fruited tree in 2 generations given that there is already a first line cross to leverage. The problem with this one is that a LOT of trees will have to be grown to segregate the traits.
All of the above could be speeded up immensely if genome level tests were available at a reasonable cost.
Why the number of generations? Because each of the crosses involves segregation for desirable traits. More generations gives more opportunity for segregation.
That’s an interesting question. I’ll give an amateur’s answer, based on my interpretation of my reading. Honestly most oil this is just speculation.
The “traits that allow astringency to be removed with simple treatments” appears to be present, more or less, in all Kakis. I’ve inferred – but I forget why – that this trait is variable. As I understand it, the varieties Triumph/Sharon and Rojo Brillante were bred and selected for this trait – they are both very amenable to CO2 treatment. So it would seem fairly straightforward to cross-breed other less cooperative Kaki varieties with more cooperative varieties in order to improve this trait.
The prospects for Virginiana are less clear. I was never able to get alcohol to work to remove astringency from Prok. I don’t know of anyone who has succeeded Why? The answer can be really simple or really complex. Is there one minor piece of DV tannin metabolism that could be modified by one dominant DK gene, or is there a multifaceted metabolic disconnect?
If we want to take a risk on the similarity of the DV and DK tannin systems, the most straightforward approach would be to introduce the C-PCNA gene. If DV and DK are similar, that gene will trigger the transformation of soluble persimmons to insoluble. Problem solved.
If we prefer to assume that there are critical differences between the DV and DK tannin systems, then it might be hopeless. But the best strategy could be to import the PCNA genes, hoping that they will stop tannin production cold.
My only quibble is that I think the Chinese PCNA x DV prospects depend on some consistency between the metabolic systems of these two species. I suspect that the C-PCNA gene won’t have anything that “speaks its language” in the DV.
One of the things I’ve learned from years of study is that species with as much in common as DV and DK always have common major biopaths. Variation will be in individual genes and in regulatory genes. Anthocyanin is one of those chemicals that is shared by almost all living plants meaning you have anthocyanin in tomatoes, in peppers, in onions, in oak trees (red and yellow leaves in fall), and in persimmons. The probability that a C-PCNA X DV cultivar could have reduced astringency in presence of the dominant gene is very high.
Japanese PCNA cultivars rely on a group of 6 recessive genes to reduce accumulation of astringency compounds. Chinese PCNA is from a dominant gene that speeds up conversion of astringency compounds to stable forms. We don’t know for sure what system affects astringency in DV, but it is more likely to be similar to C-PCNA than not. This is because DV varieties are almost all reported as astringent when unripe losing astringency as they ripen. Regardless, the way to find out is to make some crosses…
I’d believe this except: The Nature paper on C-PCNA suggests that the natural process is an upregulating of the genes that drive acetaldehyde, which in turn renders tannins insoluble. Treatment of PCAs with warm water, CO2, or alcohol also upregulates acetaldehyde. These treatments don’t seem to work on DV. I’d worry that the C-PCNA gene wouldn’t work either.
I’m still convinced that at least some of the treatments should work for the shared metabolic pathways mentioned by @Fusion_power . My suspicion is that it’s a difference of how much time they spend in a given treatment, what temperature, amount of ethanol, etc. I also suspect (but have no numbers on) that virginiana has a higher concentration of astringency that needs to be ameliorated, so of course the treatment protocol would need to be be adjusted from what works with kaki. I know you’ve done some testing already, but I’ve thought of some more variations that I intend to test out whenever these trees start producing. I really appreciate that you’ve shared your results thus far.
My hard persimmons that ripened in the sealed ziplock bag also I believe had seeds of fruit in the bag
(I remember a few drips of brown juices left in bag (or ethylene I mean from brown juice ),
but may forgot or maybe from brown calyx and moisture ?
I see Now that bear with me also stores persimmon in fridge to eat latter over months ,
and picks early to extend harvest
(I can find a quote if you’d like)
It would not be crispy , but they do turn sweet
(if any of you missed my post search plastic )
(edit remember other persimmons where ripe, (as non internet friend Tony and I gathered)
but this also was a wild 100 year old tree in terra haute IN (fruit was rock hard)
@jcguarneri – I hope you find something that works! FWIW, I tried only ethanol (not Co2 or water) but I put fruit at various stages of ripeness in a closed container with a decent sized cup of vodka for as much as 2 weeks with zero evident effect. I also tried spraying the fruit with an ethanol mist with no effect. I also mixed ethanol directly into a persimmon paste, again with zero evident effect.
That may be from a combination of other traits such as less permeable fruit. If the acetaldehyde starts out inside the fruit, the results may be entirely different. As I said earlier, the only way to find out is to make some crosses.
The only DK I have is Saijo. I need to get busy and graft some persimmons.
Keep in mind, though, that the buildup of acetaldehyde seems to follow hypoxia (low oxygen). What submersion in water, CO2, and/or ethanol vapor have in common is that they create hypoxia. Conditions that create hypoxia in Asian persimmons boost acetaldehyde and reduce astringency. Conditions that create hypoxia in American persimmons have no apparent impact on astringency.
The failure of ethanol to remove astringency in American persimmons seems unrelated to permeation of alcohol through the skin. Even direct mixing of ethanol with American persimmon paste has no impact. Rather, the issue seems to be that American persimmons react differently to hypoxia, whatever the source – immersion in water, CO2, or ethanol vapor.
None of this pessimism applies to Asian PCAs. It seems highly likely that a cross of C-PCNA x PCA would yield PCNA hybrids. We could start another thread titled, “Is a non-astringenct C-PCNA x PCA Asian hybrid persimmon within reach?”
I’ve just spent quite a bit of time reading through all the discussion. I find a lot of this really interesting.
I’ve been doing a lot of research on my own regarding the possibility of breeding a NA hybrid, and I had independently come to nearly the exact same conclusions that have generally been reached here. Personally, I was looking at 1) a cross of JT-02 and Hana Fuyu (which reportedly produces male flowers), 2) a cross that involved a C-PCNA and a receptive female DV (I know this could be hard), or 3) a C-PCNA and a cold-hardy hybrid female.
It sounds to me like some of you probably have a better handle on the ways that astringency is created/destroyed, but I’ve gleaned a lot of info here. I find it very interesting.
Sounds awesome. Please keep us posted on progress.
Understand that almost everything I know (or think I know) about “the way astringency is created/destroyed” in Kakis comes from the Nature article (Chen et al, 2017) posted. And everything I think I know about the topic in Virginiana comes from my half-assed experiments with my Prok. So I’d describe the pace of my progress as a crawl, not even a walk, and you could easily outpace me.
Re your plans, here’s my quick reaction:
C-PCNA. Can you get pollen from Luo Tian Tian Shi or similar? Given the pollen and the space, I’d cross any C-PCNA variety with all the better PCA Kakis, Virginianas, and hybrids. “All of the above.” But breaking it down . . .
a. PCA Kakis. Given limited resources, I’d prioritize the best-tasting PCAs that are known to be amenable to ethanol / CO2. Smarter people than me can make the picks, but I’m guessing Hachiya, Saiyo, maybe even Rojo Brillante. It could also make sense to cross with good PVA / PVNA types, which could then be grown seedless. But I see no point crossing C-PCNA x J-PCNA.
b. Hybrids. I like your idea of crossing C-PCNA x “a cold-hardy hybrid female.” But I think there’s an open question whether the C-PCNA gene will work in Virginiana, so I’d probably pick a hybrid with a lot of (>50%) PCA Kaki, such as Kassandra. If that works, then go crazy. I would not use a hybrid with only PCNA Kaki ancestry, such as JT-02, until it is proven that the C-PCNA gene works in DV.
c. Virginiana. Of course, we have to test whether the C-PCNA gene works in Virginiana; but yes, the cross may be difficult to execute without heroic measures such as embryo rescue. I guess I’d make this cross a low priority unless you have the technical competence.
J-PCNA. It sounds like you’re in the same place as me re JT-02, the only question is the pollen source for the back-cross. I suggested Taishu for two reasons (1) It is already the male parent; and (2) It is evidently a tasty fruit, well-accepted in the Japanese marketplace. But Hana Fuyu seems worth a try too, maybe followed by the male-flowering x-goshos. And it may be much easier to get hands on pollen from Hana Fuyu than Taishu, so go with the bird in hand.
Hope you are doing well… It’s exciting to be getting close to spring! I had a quick Q and thought I should see if you had any insights.
Do you happen to know whether Chinebuli is J-PCNA or C-PCNA? I know it was collected in Bulgaria, but I’ve gotten mixed reports as to where it originally we came from. Have you ever heard anyone discuss this?
@westonadams – I wouldn’t bet my life on this but I remember reading (somewhere on this forum, I think) that Chinebuli is Jiro. The post referenced a label that, as I recall, does not read “Jiro” exactly but rather the phonetic near-equivalent.
If true, that would make Chinebuli a Japanese PCNA.
@westonadams – Well, yes, Cliff England reported that Chinebuli survived a very cold winter when other varieties did not. That may seem to imply that it is different and there has been a lot of reckless speculation. But logic dictates that it must be a Japanese PCNA and the label said Jiro.
One thing we learned about persimmons from careful research on bud hardiness is that all varieties are very hardy when fully dormant in the depth of winter. But they become much less hardy in late winter / early spring after exposure to occasional warm temperatures. The main determinant of overall hardiness may be the speed of this emergence. For example, my Ichi Ki Kei Jiro is supposedly slow to emerge, which may account for whatever cold hardiness it exhibits.
