Trying to understand PC/PV & A/NA classifications

General Fruit Growing
#1

I’m trying to understand the classification of persimmons as PCA etc. Please check my facts / logic –

  1. PCA varieties are the original Asian persimmons. Correspondingly, nearly all Chinese and Korean persimmons are PCA.

  2. PCNA varieties are the result of a mutation that removes the ability of persimmons to store tannins. This mutation probably happened in Japan, as nearly all PCNA varieties are Japanese (and genetic variation among the PCNA varieties is low). The single gene that controls this incapacity is recessive. One Chinese variety has a different mutation that is dominant.

  3. PVA/PVNA varieties are the result of a different mutation (or mutations) that cause(s) seeds to produce ethanol. This ethanol binds tannins, reducing or eliminating astringency. PVA seeds produce less ethanol; PVNA seeds produce more – enough to eliminate astringency while the fruits are still firm. This process exposes the tannins to oxidation, which causes browning.

The variation in ethanol production across PV types seems likely to be more continuous than dichotomous, as there is considerable uncertainty as to the classification of some varieties. For example, Giboshi is classified as either PVA or PVNA by different sources.

Presumably, the PVA and PVNA varieties are just as amenable as the PCA varieties to treatment with exogenous alcohol, if the endogenous ethanol proves insufficient.

Comments?

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Fruit Hieroglyphics (Fruit Acronyms and Related Terms)
#2

I can’t check your facts, but do I know Giboshi responds just as well to CO2 treatment to remove astringency as PCA types like Giombo, Tecumseh and Eureka.

I’ve also noticed the same confusion in the classification of astringent types. One article I read online listed Picudo as PVA and Costata as PVNA, but I thought they were supposed to be the same cultivar. Other articles say Picudo is PCA. I’ve also seen Tipo listed as PVA or PVNA.

Since I’ve personally purchased several mislabeled kakis from nurseries (i.e, purported non-astringent types that ended up being astringent) and have read on the forum that others have the same experiences, I wouldn’t be surprised if researchers have used different cultivars with the same names in their work too. I imagine it would be very hard to distinguish between many PCA, PVA and PCNA types based on size and shape of the fruit alone if the fruit haven’t been pollinated.

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#3

I’ve also read that persimmons have a strong tendency to produce sports, so even a graft from a known variety can potentially be different from the parent tree. I’m not sure if the nonastringent gene is instable enough for that to be the issue. A true mislabel seems much more likely, but I think it’s worth noting sports as a possibility.

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#4

Pollination_RelationshipsAmongAsianPersimm.pdf (1.5 MB)

<< I can’t check your facts >>

Facts (as I interpreted them) come from this article. Of course it’s possible that other more recent findings suggest something different. Or that my interpretation is wrong.

<< I imagine it would be very hard to distinguish between many PCA, PVA and PCNA types based on size and shape of the fruit alone if the fruit haven’t been pollinated. >>

Agreed. And even if pollinated, it would seem hard to distinguish PVA and PVNA in some cases. Like, how many seeds are needed for the behavior to be true to type?

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