Persimmon astringency-type classification
concept / concept-kaki-astringency-type-classification
柿の甘渋性分類（PCNA/PVNA/PCA/PVA） / persimmon astringency-type classification (PCNA/PVNA/PCA/PVA)
Persimmon astringency-type classification is a horticultural classification dividing persimmon cultivars into 4 types by how their fruit loses astringency. The types are pollination-constant non-astringent (PCNA), pollination-variant non-astringent (PVNA), pollination-constant astringent (PCA), and pollination-variant astringent (PVA), with distinct mechanisms of astringency loss and inheritance.
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Reading the bitterness
Persimmon cultivars are classified into 4 types according to how their fruit loses astringency. In pollination-constant non-astringent (PCNA) fruit, soluble tannin accumulation stops early in development, and dilution as the fruit enlarges then reduces astringency. Kanzaki (2016) regards this as a mutant lacking the capacity to accumulate tannins and characterizes it as a recessive qualitative trait controlled by a single gene. The oldest Japanese PCNA cultivar is described as 'Gosho', recorded in the 17th century.
In pollination-variant non-astringent (PVNA) fruit, acetaldehyde produced by the seeds renders soluble tannins insoluble late in fruit development, reducing astringency. According to Kanzaki (2016), this is a quantitative trait controlled by multiple genes and relatively readily passed to offspring, so PVNA cultivars spread throughout Japan and are numerous. The oldest Japanese PVNA cultivar is described as 'Zenjimaru', discovered in the 13th century.
By contrast, there are 2 types of astringent persimmon. Pollination-constant astringent (PCA) fruit retains strong astringency throughout the flesh even after ripening, whether or not seeds form. In pollination-variant astringent (PVA) fruit, astringency is not sufficiently removed even when seeds form: brown specks (goma) appear only around the seeds, while the flesh as a whole remains astringent (Kanzaki, 2016). For the new cultivar 'Taiten' reported by Yamada et al. (2012), strong astringency at ripening was confirmed in some regions of the regional adaptation trials, and it was classified as PVA. This case shows that the degree of astringency loss in a PVA cultivar can vary by region and year.
The astringency-loss type of the Chinese-origin non-astringent cultivar 'Luotian Tianshi' is called C-PCNA and is described as having a different mode of inheritance and mechanism from Japanese PCNA. According to Kanzaki (2016), PCNA is recessive, whereas C-PCNA is inherited as a dominant trait. In PCNA, expression of genes involved in flavonoid synthesis within the tannin synthesis system decreases early in fruit development. In C-PCNA, those genes continue to be expressed until late development, while expression of genes involved in tannin accumulation decreases. 'Luotian Tianshi' was reported as a Chinese-origin non-astringent persimmon cultivar in 1982.
Sources for this overview
Checked for this overview: Used a verbatim check of the mechanism described for PCNA as support for this paragraph. / Used a verbatim check of the mechanism described for PVNA as support for this paragraph. / Used a verbatim check of the distinction between PCA and PVA as support for this paragraph. / Used a verbatim check of the difference in inheritance of C-PCNA as support for this paragraph.
Checked for this overview: Used the PVA classification of 'Taiten' as support for this paragraph.
Structured claims — open a section to read each claim's confidence, evidence and limits
Mechanism and receptors (4)
Note: Kanzaki (2016).
Show data
concept-kaki-astringency-type-classification —has_currently_proposed_mechanisms→ "In PCNA (complete non-astringent persimmons), accumulation of soluble tannin stops early in fruit development, and de-astringing then proceeds through dilution as the fruit subsequently enlarges. It is regarded as a mutant that has lost the ability to accumulate tannin, and is a recessive, single-gene-controlled qualitative trait. The oldest PCNA cultivar in Japan is 'Gosho', reported in the 17th century."Note: Kanzaki (2016).
Show data
concept-kaki-astringency-type-classification —has_currently_proposed_mechanisms→ "In PVNA (incomplete non-astringent persimmons), acetaldehyde produced by the seeds renders soluble tannin insoluble late in fruit development, and de-astringing proceeds. It is a quantitative trait controlled by multiple genes and is relatively easily inherited by later generations, so PVNA cultivars have spread throughout Japan and many cultivars exist. The oldest PVNA cultivar in Japan is 'Zenjimaru', discovered in the 13th century."Note: Kanzaki (2016). Yamada et al. (2012) report, as a concrete example concerning the new cultivar 'Taiten', that 「系統適応性検定試験の一部の場所では熟期に強い渋みがあったことからPVA品種であった」 (in translation: “at some sites in the regional adaptability trial, strong astringency was present at ripening, so it was a PVA cultivar”), showing that the degree of de-astringing in PVA cultivars can vary by region and year.
Show data
concept-kaki-astringency-type-classification —has_currently_proposed_mechanisms→ "In PCA (complete astringent persimmons), strong astringency remains throughout the flesh even at maturity, regardless of whether seeds have formed. In PVA (incomplete astringent persimmons), even when seeds form, de-astringing is insufficient, and brown speckling (goma) appears only around the seeds, with astringency remaining in the flesh as a whole."Note: Kanzaki (2016). 'Luotian Tianshi' was reported in 1982 as a non-astringent persimmon cultivar native to China, and a trait survey after its introduction to Japan found it to be a type distinct from PCNA (C-PCNA).
Show data
concept-kaki-astringency-type-classification —has_currently_proposed_mechanisms→ "The de-astringing type of 'Luotian Tianshi', a complete non-astringent persimmon native to China, is called C-PCNA, and has a different mode of inheritance and mechanism from Japan's PCNA. PCNA is a recessive trait, but C-PCNA is inherited as a dominant trait. In PCNA, expression of the genes involved in flavonoid synthesis, within the tannin synthesis system, falls early in fruit development, whereas in C-PCNA these genes continue to be expressed until late in development, while expression of the genes involved in tannin accumulation falls."