Tony – As you know, I’m a strong advocate of this cross. My original rationale was that this seems the quickest route to a cold hardy, good tasting, non-astringent hybrid. But you’re right, increased size would be an additional benefit, provided that we can preserve the cold-hardiness.
Elsewhere, a forum member (I forget who) proposed PVNA x JT-02. The rationale was that as JT-02 already displays some PVNA behavior (at least in one report), this could be an even quicker route to a cold hardy, good tasting, non-astringent hybrid – just one with seeds.
@gibberellin writes: << Seeds in Fuyu have no obvious effect on flavor in my experience. >>
@Richard writes: << The seeded fruit have a more pronounced, appealing flavor. >>
I have no reason to doubt either observation. So I’d like to understand the difference. As Richard notes, climate may matter; but both posters live in a warm climate. If climate explains the difference, it must be something more subtle.
I’ll return to one of my questions in the OP: Does the pollinator matter?
Richard says that he has << not read any clear answers in the literature. >> I haven’t either. I haven’t even seen speculation (such as mine) that the genes carried from the male parent in the pollen might have an impact. My very speculative hypothesis is that Fuyu pollinated by a PCNA male or PCA male will not exhibit changes in color, flavor and astringency, whereas Fuyu pollinated by a PVNA male (e.g., Chocolate) will exhibit such changes.
So I’m asking for reports of your personal experience. If you eat seeded Fuyu or Taishu or JT-02, please supply three bits of data: Does the seeded fruit exhibit PVNA behavior – dark flesh and early non-astringency? Does the seeded fruit taste better? And if possible, what variety or varieties supplied the pollen? Thanks!!!
Due to the move this July so my ten in ground JT-02 won’t flowers until another couple of years and by then my third leaf potted Taishu should have plenty of male flowers to cross them all.
The PVNA D. kaki ‘Chocolate’ sold by retailers in California has pistillate and staminate flowers. It is considered a mutant of Tsurunoko – a pistillate-constant PVNA. Tsurunoko is also known as ‘Chocolate’, but only in some commercial settings and overseas. Further, there are two Tsurunoko strains – the original from Japan vs the one presently grown commercially in CA.
Based on the observations, it seems more consistent with PVA persimmons than PVNA.
JT02 appears to have dark flesh when pollinated. But doesn’t lose astringency until fully soft.
This is textbook PVA, isn’t it so?
When I had Rojo Brillante, this is what I used to see.
As I understand it, the PVNA trait (pollination variant non-astrigency) appears on a continuum that probably reflects the number of PVNA alleles in the variety. I say “probably” because we don’t know for sure; we can only infer from the behavior of intra-specific (i.e., all Kaki) hybrids. It would be similar to height or skin color in humans, except humans have two sets of chromosomes and persimmons have six.
So hypothetically, (1) a Kaki variety with 0-1 PVNA alleles would show no PVNA tendency (i.e., no change in flesh or astringency when seeded) and be classified as PCA; (2) a Kaki variety with 2-3 PVNA alleles would show a slight or moderate PVNA tendency (i.e., some flesh and astringency change when seeded, but not enough to achieve full non-astringency before ripening) and be classified as PVA; and (3) a Kaki variety with 4-6 PVNA alleles would show a strong PVNA tendency (i.e., significant change in flesh and complete loss of astringency before ripening) and be classified as PVNA.
Thus when a full PVNA Kaki variety (presumably with 5-6 PVNA alleles) is crossed with a non-PVNA variety (presumably with 0-1 PVNA alleles), the offspring tends to be PCA (presumably with 1-3 PVNA alleles). We can see this in the Japanese crosses of Kurokuma (PVNA) x Taishu (PCNA), which resulted in the releases of Taiten (2007) and Taigetsu (2009), both classified by the breeders as astringent, PVA.
Based on your description of its behavior, you are right that JT-02 would be considered PVA. It inherited no PVNA alleles from its Virginiana mother and probably only 1-2 from its Kaki father. [But for this neat explanation of JT-02’s behavior to be true, Taishu would have to have some PVNA alleles.].
Of course, all of this discussion of JT-02 is complicated by its admixture of Virginiana and Kaki metabolism. It’s tough enough inferring what’s going on in Kakis. It’s a crap shoot how 1-3 PVNA alleles would perform in a 50-50 Kaki-Virgiana hybrid. And again, maybe the pollinator matters.
May I ask: What Kaki variety pollinates your PCA JT-02?
I think we’re conditioned to think of observed traits as correlating neatly with one or at most a few genes. Thats what Mendel showed, after all. From what Ive gathered, that was an extremely rare case that is quite atypical of the way genetics and gene expression play out by and large.
You’re right that an allele does not necessarily refer to a change within a gene sequence, but it does refer to a specific DNA sequence. You could make an argument that heritable epigenetic markers are functionally like alleles, but that’s not really how the term is used. Well anyway, it’s just a definition.
There’s no need to go down this semantic rabbit hole here. The main impact of such semantic quibbles is to distract the discussion from its intended topic.
My questions in the OP talked only about observed behavior. I never mentioned genes or alleles. We can keep the discussion at that level. Genes came up because @disc4tw brought up chromosomes and then I started to speak of genes and alleles just to answer his question. But I’d be perfectly happy to focus solely on the original questions.
FWIW, in my posts above, I use the term “allele” to mean gene variant. For example, one gene variant produces astringent Kakis (PCA), another gene variant produces non-astringent Kakis (PCNA). Admittedly I sometimes say “:gene” when I should have said “allele.”
Imagine a 2 x 2 table for all reports of seeded JT-02. Rows are Pollen Donor (A) PVNA, (B) Not PVNA; columns are JT-02 Flesh (A) Pollination Variant, (B) Not Pollination Variant.
@ramv – Your report immediately above provides the first entry. You have reported that a PVNA pollen donor (Row A) produced PV flesh in JT-02 (Column A).
The brown color in pollinated PVNA persimmons is from tannins, which are polymeric flavonoids. Astringency is largely due to leucodelphinidin, a monomeric flavonoid, which is colorless and occurs at much lower concentrations in Fuyu and other PCNA cultivars. I think its possible that Fuyu has several PVNA alleles and the trait simply doesn’t show visually except in instances where leucodelphinidin content happens to be high enough for browning to occur.
@GrapeNut – I think that what you wrote is misleading. The astringency in ALL persimmons is due to various tannins. See more below.
Both the loss of astringency and the change in color in PVNA persimmons seems to be due to an interaction of the tannins with ethanol. Seeds have no impact on the astringency or color of a PCA persimmon. But seeds do impact both the astringency and color of a PVNA persimmon. Why? The seeds of a PVNA persimmon produce ethanol. This ethanol is then involved in chemical reactions that render the tannins insoluble; and insoluble tannins do not react with saliva. The ethanol apparently causes other changes to color.
You say that the brown color in PVNA persimmons is due to tannins. But the brown color in PVNA persimmon does not emerge unless there are seeds. The brown color cannot therefore be due solely to the tannins, which are present whether there are seeds or not. Moreover, the brown color shows up in seeded Fuyus, which have low tannin. The seeds in Fuyu produce ethanol just like the seeds in PVNAs. See the attached article. This suggests that the ethanol is responsible for the brown flesh – even in a variety with no tannins!
Here’s how my ChapGPT described “types of tannins in persimmons”:
<< Persimmons contain various types of tannins, which are responsible for their unique taste and astringent properties, especially when unripe. The main types of tannins found in persimmons are:
Proanthocyanidins (Condensed Tannins): These are the most abundant type of tannins in persimmons. Proanthocyanidins are a class of polyphenols that contribute to the astringency of unripe persimmons. They have the ability to bind with proteins, which causes the mouth-puckering sensation.
Catechins: A type of flavonoid, catechins are also present in persimmons. They are a form of condensed tannin and contribute to the bitter taste and astringency of the fruit.
Gallic Acid and Ellagic Acid (Hydrolyzable Tannins): These tannins can be hydrolyzed into sugar and phenolic acids. They are less abundant in persimmons compared to proanthocyanidins but still play a role in the fruit’s astringency and flavor profile.
Tannic Acid: Though not as prominent as proanthocyanidins, tannic acid is another type of tannin found in persimmons. It contributes to the astringent properties of the fruit.
These tannins undergo significant changes during the ripening process of persimmons. As the fruit ripens, the level of soluble tannins decreases, which reduces the astringency and makes the fruit more palatable. Different varieties of persimmons may have varying levels and types of tannins, influencing their taste and texture. >>
From what I understand, browning in persimmons is essentially the same process that happens in apples, avocados, tea leaves, etc.
Sure, but without polyphenols, of which tannins are the major component in persimmons, you cannot get browning. The color is due to those molecules polymerizing. Ethanol (or acetaldehyde rather) is the catalyst. Tannins are the substrate.
My point is that given the inconsistency in brown color development in Fuyu, and given that Fuyu can exhibit some astringency and therefore high tannin levels in some conditions, the trait only occurs when you have conditions for both seed formation and higher than normal tannin levels.
Another result of tannins becoming insoluble is the development of color as the molecules get larger and bonds are formed between monomers.
