Pollination-constant And Non-astringent Research Articles

Quantitative genotyping of CPCNA locus advances genetic strategies in PCNA persimmon breeding

Persimmon (Diospyros kaki Thunb., 2n = 6x = 90) is a major fruit crop in eastern Asia, known for its unique in accumulating large amounts of proanthocyanidins (PAs) in the fruit flesh, resulting in strong astringency. The Pollination constant and non-astringent (PCNA) mutation, characterized by reduced PAs, allows for consumption before softening, akin to an apple. Two distinct types of PCNA persimmons, Japanese PCNA (J-PCNA) and Chinese PCNA (C-PCNA), exhibit different genetic regulatory mechanisms. The J-PCNA type is conferred by homozygous recessive alleles (ast), while C-PCNA possesses at least one dominant allele (CPCNA) at the CPCNA locus. The probability of generating PCNA individuals depends on the presence of ast or CPCNA alleles in parental plants. Previous research has quantified dosages of AST alleles in major Japanese cultivars, the status of AST alleles, especially CPCNA alleles, in Chinese cultivars remains undisclosed. This lack of understanding creates a significant obstacle in PCNA persimmon breeding efforts, particularly for the C-PCNA type. In this study, we developed a method to quantify the CPCNA locus by detecting the allele dosage of RO2, a marker strongly associated with CPCNA alleles across cultivars, using quantitative real-time PCR (qPCR). Our findings reveal that most C-PCNA cultivars and androecious germplasm exhibiting the PCNA trait contain only one CPCNA allele (Bbbbbb). Furthermore, we observed that the average ast allele dosage in Chinese genotypes was lower than that in Japanese non-PCNA genotypes. Quantifying the CPCNA locus assists in selecting PCNA candidate and also cultivating parents with sufficient CPCNA alleles (more than quadruple dose), ensuring that the offspring crossed with non-PCNA types inherit the PCNA trait. This approach will undoubtedly accelerate the breeding of novel PCNA cultivars and could also prevent inbreeding depression in PCNA breeding practices when crosses between J-PCNA cultivars. Our method provides crucial insights for enhancing PCNA persimmon breeding programs and advancing the development of improved cultivars.

Characterization of a gene regulatory network underlying astringency loss in persimmon fruit.

Transcriptome analysis of a persimmon population segregating for an astringency trait in fruit suggested central roles for a limited number of transcriptional regulators in the loss of proanthocyanidin accumulation. Persimmon (Diospyros kaki; 2n=6x=90) accumulates a large amount of proanthocyanidins (PAs) in its fruit, resulting in an astringent taste. Persimmon cultivars are classified into four types based on the nature of astringency loss and the amount of PAs at maturity. Pollination constant and non-astringent (PCNA)-type cultivars stop accumulating PAs in the early stages of fruit development and their fruit can be consumed when still firm without the need for artificial deastringency treatments. While the PCNA trait has been shown to be conferred by a recessive allele at a single locus (ASTRINGENCY; AST), the exact genetic determinant remains unidentified. Here, we conducted transcriptome analyses to elucidate the regulatory mechanism underlying this trait using developing fruits of an F1 population segregating for the PCNA trait. Comparisons of the transcriptomes of PCNA and non-PCNA individuals and hierarchical clustering revealed that genes related to the flavonoid pathway and to abiotic stress responses involving light stimulation were expressed coordinately with PA accumulation. Furthermore, coexpression network analyses suggested that three putative transcription factors were central to the PA regulatory network and that at least DkMYB4 and/or DkMYC1, which have been reported to form a protein complex with each other for PA regulation, may have a central role in the differential expression of PA biosynthetic pathway genes between PCNA and non-PCNA.

An integrated analysis based on transcriptome and proteome reveals deastringency-related genes in CPCNA persimmon

Persimmon fruits accumulate a large amount of proanthocyanidins (PAs) during development. PAs cause a dry or puckering sensation due to its astringency. Pollination constant and non-astringent (PCNA) persimmon fruits can lose astringency during fruit ripening. However, little is known about the mechanism of natural de-astringency of Chinese PCNA (CPCNA). To gain insight into the molecular events of CPCNA natural de-astringency, we used mRNA-seq and iTRAQ-based quantitative proteomic analysis to measure changes in genes and proteins expression at two key stages of natural astringency removal (i.e. 10 and 20 weeks after bloom) and water-treated (i.e. 40 °C·12 h) de-astringency fruits. Our analyses show that the three predominantly process in CPCNA de-astringency: (1) water treatment strongly up-regulates glycolysis/acetaldehyde metabolism, (2) expression of genes/proteins involved in PA biosynthetic pathway was remarkably reduced in natural and water-treated de-astringency, (3) sugar metabolism and ethylene related pathway were quite abundant in natural de-astringency. We also found ethylene-related TFs were quite abundant in natural de-astringency, followed by WRKY and NAC transcription factors. These results provide an initial understanding of the predominantly biological processes underlying the natural de-astringency and “coagulation effect” in CPCNA.

Androecious Genotype ‘Male 8’ Carries the CPCNA Gene Locus Controlling Natural Deastringency of Chinese PCNA Persimmons

The androecious genotype of Diospyros spp. ‘Male 8’, which is distributed in Dabie Mountain area of the central China, was probably derived from the hybrids or natural variation of Chinese pollination constant and non-astringent (CPCNA) persimmon. Its application potential as the breeding parent of pollination constant and non-astringent (PCNA) is undefined. In this study, we identified the astringency type of a hybrid individual (H8-2) derived from the cross between ‘Huashi 1’ (pollination variant and astringent, PVA) and ‘Male 8’. Through comparison with the known genotypes of CPCNA, Japanese PCNA (JPCNA) and non-PCNA, the results of soluble/insoluble tannin content and tannin cell size measure showed that H8-2 was a PCNA genotype with the characteristic of natural deastringency of CPCNA. According to the currently known genetic features of PCNA persimmon, a new individual of PCNA may be generated in F1 population when two JPCNA genotypes are crossed or when the CPCNA genotype is used as a parent. Thus, the study verifies that androecious genotype ‘Male 8’ carries the dominant gene locus that controls the non-astringent trait of CPCNA, indicating its potential to be used as pollen donor for the genetic improvement of PCNA persimmon.

SCAR Markers for Practical Application of Marker-assisted Selection in Persimmon (Diospyros kaki Thunb.) Breeding

In previous studies, we have developed molecular markers linked to the AST locus that controls fruit astringency type in persimmon; however, these markers are not feasible for practical application to breeding programs since they are not fully effective for discriminating the pollination constant and non-astringent (PCNA) genotype from the non-PCNA genotype in a progeny derived from ‘Kurokuma’. Here we developed new sequence characterized amplified region (SCAR) markers that enable easy and reliable selection of the PCNA genotype from breeding populations. Genomic regions adjacent to probe 5R, which showed polymorphic fragments between PCNA and non-PCNA genotypes in restriction fragment length polymorphism (RFLP) analysis, were isolated from the genomic libraries of ‘Nishimura-wase’, ‘Jiro’, and ‘Kurokuma’-derived offspring. The isolated genomic regions were characterized and 3 insertion/deletion mutations were observed between ast- and AST-linked regions. Several primers were designed in the flanking region of Indel-3 and, in multiplex PCR, it was shown that using 2 forward primers, AST-F and PCNA-F and a reverse primer, 5R3R, is the most useful and reliable primer set. The AST-linked 220-bp fragment proved to be a common marker of ‘Kurokuma’-, ‘Nisimura-wase’- and ‘Aizumishirazu’-derived progenies. This multiplex PCR is considered the most practical tool for marker-assisted selection (MAS) and can enhance and accelerate progress in persimmon breeding.

Expression balances of structural genes in shikimate and flavonoid biosynthesis cause a difference in proanthocyanidin accumulation in persimmon (Diospyros kaki Thunb.) fruit

Persimmon fruits accumulate a large amount of proanthocyanidin (PA) during development. Fruits of pollination-constant and non-astringent (PCNA) type mutants lose their ability to produce PA at an early stage of fruit development, while fruits of the normal (non-PCNA) type remain rich in PA until fully ripened. To understand the molecular mechanism for this difference, we isolated the genes involved in PA accumulation that are differentially expressed between PCNA and non-PCNA, and confirmed their correlation with PA content and composition. The expression of structural genes of the shikimate and flavonoid biosynthetic pathways and genes encoding transferases homologous to those involved in the accumulation of phenolic compounds were downregulated coincidentally only in the PCNA type. Analysis of PA composition using the phloroglucinol method suggested that the amounts of epigallocatechin and its 3-O-gallate form were remarkably low in the PCNA type. In the PCNA type, the genes encoding flavonoid 3'5' hydroxylase (F3'5'H) and anthocyanidin reductase (ANR) for epigallocatechin biosynthesis showed remarkable downregulation, despite the continuous expression level of their competitive genes, flavonoid 3' hydroxylation (F3'H) and leucoanthocyanidin reductase (LAR). We also confirmed that the relative expression levels of F3'5'H to F3'H, and ANR to LAR, were considerably higher, and the PA composition corresponded to the seasonal expression balances in both types. These results suggest that expressions of F3'5'H and ANR are important for PA accumulation in persimmon fruit. Lastly, we tested enzymatic activity of recombinant DkANR in vitro, which is thought to be an important enzyme for PA accumulation in persimmon fruits.

CONSTRUCTION OF A RELIABLE PCR MARKER FOR SELECTING POLLINATION CONSTANT AND NON-ASTRINGENT (PCNA) TYPE OFFSPRING AMONG BREEDING POPULATION OF PERSIMMON (DIOSPYROS KAKI THUNB.)

Pollination constant and non-astringent (PCNA) type persimmons, which lose their astringency naturally on the tree, are the most desirable for fresh fruit consumption. The trait of natural astringency-loss in PCNA type is recessive and controlled by a single locus, known as AST locus. Because PCNA type cultivars are of recent origin and exist only in a small number of cultivars, inbreeding depression resulting from repeated crosses among very few cultivars and/or selections is a major challenge facing the current breeding of new PCNA type cultivars. One solution to overcome this inbreeding depression is to include non-PCNA cultivars in the breeding project to extend the genetic pool by utilizing the wide diversity found in non-PCNA cultivars. However, to date, F 1 populations resulting from crosses between PCNA and non-PCNA type cultivars/selections have yielded only non-PCNA offspring. To obtain PCNA offspring, F 1 progeny needs to be backcrossed to PCNA type cultivars/selections. As persimmon is hexaploid, the obtainable rate of PCNA offspring in a backcross population is only 10-15%. Although we identified AFLP and RFLP markers tightly linked to the trait of natural astringency-loss in persimmon, these markers could not distinguish some non-PCNA progenies in other breeding populations. Previously, we demonstrated that RFLP markers derived from fosmid clones of D. lotus, diploid relatives of D. kaki, could be used to distinguish between PCNA and non-PCNA types of D. kaki, and established the possibility of extending this approach to PCR based markers. In this study, we describe the development of PCR-based markers derived from fosmid clones of D. kaki and D. lotus, and confirm their effectiveness across diverse progenies to select PCNA type.

PERSIMMON PRODUCTION AND COMMERCIALIZATION IN BRAZIL: AN OVERVIEW

PERSIMMON PRODUCTION AND COMMERCIALIZATION IN BRAZIL: AN OVERVIEW

Conversion of RFLP Markers for the Selection of Pollination-Constant and Non-Astringent Type Persimmons (Diospyros kaki Thunb.) into PCR-Based Markers

Persimmon (Diospyros kaki Thunb.) cultivars are classified into 4 types depending on the relationship between astringency of the mature fruit and the effect of seeds on the loss of astringency, and only pollination-constant and non-astringent (PCNA)-type persimmons stably lose fruit astringency as a part of fruit development. This is a recessive trait, regarded to be controlled by a single locus, namely, the AST locus, which has a polysomic nature. Thus far, we have identified 2 restriction fragment length polymorphism (RFLP) markers, namely, A1 and A2, each of which is separately linked to a different AST allele, and proved that the RFLP markers were useful for selecting PCNA-type persimmons. This study was conducted to convert the RFLP markers into polymerase chain reaction (PCR)-based markers. We isolated and characterized genomic regions corresponding to each RFLP marker by inverse PCR. Two primer pairs, E4/E9r and E4/A2r, were designed to generate 2 sequence characterized amplified region (SCAR) markers, i.e., PCR-A1 and PCR-A2, respectively. The PCR-A1 and PCR-A2 markers cosegregated with the A1 and A2 markers, respectively, in ‘Nishimura-wase’-derived progenies. Although the primer pair E4/A2r did not produce the PCR-A2 marker in the FU-275, which is a progeny derived from ‘Aizumishirazu’, all non-PCNA-type offspring but no PCNA-type offspring showed the PCR-A1 marker using the primer pair E4/E9r. Thus, it was revealed that the SCAR markers were useful for selecting PCNA-type offspring in these progenies. On the other hand, disruption of the relationship between the markers and the AST locus was observed in the KU-325, derived from ‘Kurokuma’, indicating that the selection of PCNA-type offspring using PCR-based markers is not effective for progeny derived from ‘Kurokuma’. Herein, we discuss the possibility of applying PCR-based markers to genetic studies.

RFLP Markers for the Selection of Pollination-constant and Non-astringent (PCNA)-Type Persimmon and Examination of the Inheritance Mode of the Markers

We investigated marker-assisted selection of the pollination constant and non-astringent (PCNA) trait and inheritance modes of the marker locus in persimmon (Diospyros kaki Thunb.) using restriction fragment length polymorphism (RFLP) analysis. In two backcross progenies, FU-170 and FU-275, 5 of 71 and 23 of 101 offspring, respectively, were judged as PCNA genotype by the marker phenotype. The astringency type of individual offspring was determined by measuring the size of tannin cells and soluble tannin content in mature fruit, thus confirming complete co-segregation of RFLP markers and the non-PCNA phenotype in 32 and 68 fruit-obtainable offspring from FU-170 and FU-275, respectively; therefore, RFLP markers can be used for PCNA genotype detection. Their segregation ratio deviated significantly from that of disomic inheritance. We also discuss the possibility of polysomic inheritance of RFLP markers.

(110) Suppression Subtractive Hybridization (SSH) Analysis for Detecting Genes Involved in Condensed Tannin Accumulation in Persimmon Fruit

Pollination-constant and non-astringent (PCNA)-type persimmon has probably originated from astringent (non-PCNA)-type as a mutant that terminates condensed tannin accumulation at an early stage of fruit development. This trait is confirmed to be recessive and is controlled by a single locus. Since PCNA-type fruit stops tannin accumulation at an early stage, comparison of the gene expressions between PCNA- and non-PCNA-type will reveal the genes conferring condensed tannin accumulation in persimmon fruit. We performed suppression subtractive hybridization (SSH) analysis for detecting differentially expressed genes in non-PCNA-type fruit using BC1 offspring from a cross between PCNA `Fuyu' and non-PCNA “275-13” (F1 progeny derived from non-PCNA `Aizumishirazu' × PCNA `Taishu'). Fruits from seven individuals of PCNA or non-PCNA offspring in BC1 were sampled at early two stages of fruit development and total RNA was extracted by hot borate method from each fruit of different stage. Then, RNA was pooled as PCNA or non-PCNA bulk at two stages and cDNA was synthesized from each bulk for SSH analysis. A total of 5000 clones expressed differentially in non-PCNA-type fruit were picked from SSH library of two stages and 198 positive clones confirmed by differential screening were sequenced. The homologous sequences for the genes involved in flavonoid biosynthesis (CHS, CHI, F3H, F3'5'H, DFR, UFGT, and ANS) were obtained from the clones. The genes that are not considered to be involved in flavonoid biosynthesis so far (SCPL and DHQ) were also detected with high frequencies. We will discuss the role of these genes for condensed tannin accumulation in persimmon fruit.

Genetic Relationships of some PCNA Persimmons (Diospyros kaki Thunb.) from China and Japan revealed by SRAP analysis

Sequence-related amplified polymorphism (SRAP) marker was employed to analyze genetic relationships of 10 Chinese, 11 Japanese varieties of persimmon and its 6 relatives. Twenty out of 72 primer combinations could amplify clearly and consistently. Just only one primer set could discriminate all the genotypes used in this study. The genetic relationships were analyzed using unweighted pair-group method of arithmetic average cluster analysis (UPGMA) and principal coordinated analysis (PCOA). The results showed: Chinese varieties were grouped into two clusters, while the Japanese varieties were grouped into one cluster with two subgroups. The persimmon relatives were clustered together. Probably, Chinese and Japanese Pollination-constant and Non-astringent (PCNA) persimmons had different genetic background. ‘Eshi No.1’ from Hubei province was close to Male type 6. ‘Xiangxitianshi’ from Xiangxi municipality, Hunan province, had a high similarity coefficient with ‘Maekawa-Jirou’ and was clustered in the Japanese varieties group, indicating that ‘Xiangxitianshi’ maybe close to the Japanese variety in terms of genetic background. The Chinese Pollination-constant and Astringent (PCA) and PCNA persimmons were not distinctly distinguished implying that the non-astringent trait of Chinese PCNA type might result from the PCA type.

A New Dominant Trait of Natural Astringency Loss of Persimmon (Diospyroskaki Thunb.) Found in a Chinese PCNA `Luo Tian Tian Shi'

There is a non-astringent type of persimmon that loses its astringency naturally on trees, despite the absence of seeds. This type is called pollination-constant and non-astringent (PCNA)-type. PCNA-type was thought to have originated in Japan as a mutant that terminates tannin accumulation at an early stage of fruit development. This trait is confirmed to be recessive and the PCNA-type must be homozygous in all alleles. In fact, crossing among PCNA-type individuals yields only the PCNA-type in F1, while crossing between PCNA-type and non-PCNA-type yields only the non-PCNA-type. However, a new PCNA cultivar, `Luo Tian Tian Shi', was reported in 1982 to exist in Luo Tian County, China, and this PCNA-type seemed to have different mechanisms to be PCNA-type. Our previous report showed that a crossing between `Luo Tian Tian Shi' and Japanese PCNA `Taishu' yielded both PCNA-type and astringent-type in F1, indicating that the trait of PCNA in `Luo Tian Tian Shi' may be dominant. To confirm this hypothesis, we made crossings between `Luo Tian Tian Shi' and Japanese astringent-type `Yotsumizo' or `Iwasedo', and top-grafted these seedlings for earlier fruiting. As we had some fruits in a total of 25 F1 individuals last year, we investigated segregation of astringency among these individuals. We also confirmed the parental relationships of these progenies by analyzing several SSR markers. We confirmed the segregation of PCNA-type and astringent-type in F1. No mistake of artificial pollination was shown in all individuals by SSR markers. Thus, we concluded that the trait of astringency-loss in `Luo Tian Tian Shi' is dominant and the use of this cultivar as a parent will open a new window for breeding PCNA-type persimmon.

Segregation for fruit astringency type in progenies derived from crosses of [formula omitted] constant non-astringent genotypes in oriental persimmon ( Diospyros kaki Thunb.)

There are very few early ripening, pollination constant and non-astringent (PCNA) cultivars of oriental persimmon ( Diospyros kaki Thunb.), which are hexaploid, and it has been an important breeding target to develop early ripening PCNA cultivars with no fruit cracking. PCNA is completely recessive to non-PCNA types, and no PCNA offspring have yet resulted from crossings between PCNA and non-PCNA local cultivars of Japanese origin. ‘Nishimurawase’, a non-PCNA cultivar, has been believed to be an F 1 from a cross between PCNA and non-PCNA cultivars. In addition, it is an early ripening leading cultivar in Japan with little fruit cracking that has potential to yield early ripening offspring. When ‘Nishimurawase’ was crossed with six PCNA cultivars and selections, no PCNA offspring occurred among 95 offspring. Two F 1 offspring (‘170-10’ and ‘170-26’) were selected from an ‘Okitsu-25’ ( PCNA)ב Nishimurawase’ cross, and when crossed with PCNA genotypes, they produced 23 and 15%, respectively, PCNA genotypes. These percentages of PCNA offspring were nearly the same as the 15% produced from the backcross (non-PCNA×PCNA)×PCNA, as reported earlier. Thus, ‘Nishimurawase’ has no advantage in getting PCNA offspring than other local non-PCNA cultivars, and it was probably not an F 1 from a cross between PCNA and non-PCNA genotypes.

Identification of Molecular Markers Linked to the Trait of Natural Astringency Loss of Japanese Persimmon (Diospyros kaki) Fruit

Japanese persimmon (Diospyros kaki Thunb.) cultivars are classified into four types depending upon the nature of astringency loss of the fruit. Among them, the pollination-constant and nonastringent (PCNA) type is the most desirable for fresh fruit consumption due to the trait of stable loss of astringency on the tree with fruit development. Lack of tannin accumulation is the main cause of natural astringency loss in PCNA-type fruit, and is qualitatively inherited. The PCNA trait is recessive to the non-PCNA trait. In this study, we investigated amplified fragment length polymorphism (AFLP) markers for the trait of natural astringency loss of PCNA-type fruit using bulked segregant analysis (BSA) for efficient selection of PCNA type plants in a breeding population. A total of 128 primer combinations were tested and one AFLP marker was found to be linked to the dominant allele controlling the trait for astringency. This marker, EACC/MCTA-400, was absent in all of the PCNA-type plants tested, whereas it was present in about half of the non-PCNA-type plants tested. However, RFLP analysis using this marker enabled the detection of the other dominant allele, and all PCNA-type plants could be distinguished from the non-PCNA-type plants. Application of this marker system will be useful for the selection of PCNA-type plants in persimmon breeding.

Evaluation of RFLP Analysis for Discriminating PCNA Genotype in Some Persimmon Cultivars.

The cultivation of the PCNA (pollination-constant and non-astringent)-type persimmon is advantageous because of its natural loss of astringency on the tree. We previously found RFLP markers linked to the dominant alleles controlling the PCNA/non-PCNA trait and showed that the PCNA genotype could be distinguished from non-PCNA genotype by these markers in the breeding populations. In this study, RFLP markers were investigated with 33 persimmon cultivars. All PCNA cultivars except for Chinese 'Luo Tian Tian Shi', had identical banding pattern, whereas the non-PCNA cultivars exhibited many polymorphic bands. Thus, we could distinguish PCNA cultivars of Japanese origin from non-PCNA cultivars by the RFLP analysis, although 'Luo Tian Tian Shi' was mistakenly classified as a non-PCNA type. These results suggest that this marker system could be applied to distinguish PCNA cultivars of Japanese origin from non-PCNA ones.

Analysis of the Genetic Relationships among Pollination-constant and Non-astringent(PCNA) Cultivars of Persimmon (Diospyros kaki Thunb.) from Japan and China using Amplified Fragment Length Polymorphism(AFLP).

The genetic relationships among 19 pollination-constant and non-astringent (PCNA) cultivars and 14 non-PCNA cultivars of persimmon (Diospyros kaki Thunb.), including one Chinese PCNA cultivar 'Luo Tian Tian Shi', were analyzed by comparing 138 AFLP markers. A phylogenetic tree constructed based on the similarity indices of these AFLP markers indicated a close relationship among Japanese PCNA cultivars, but a more distant relationship with the Chinese PCNA cultivar 'Luo Tian Tian Shi'. The close relationship between PCNA cultivars native to Gifu prefecture was distinct, indicating that these cultivars developed from crosses among restricted sources in this region. The cultivars 'Gosho', 'Hana-gosho', 'Oo-gosho', and 'Yamato-gosho' showed a close relationship with some non-PCNA cultivars.

カキの茎頂培養における品種間差異

Shoot tip culture was applied to 139 Japanese persimmon cultivars and four Diospyros species, D. japonica, D. lotus, D. oleifera and D. virginiana, and shoot growth in shoot tip culture was investigated in relation to each cultivar′s characteristics, fruit type, tree vigor and earliness of sprouting time. Shoot tips, 1mm in diameter, were excised from dormant axillary buds and cultured in Murashige and Skoog′s medium containing half-strength nitrogen plus 10-5M zeatin, 3 % sucrose and 0.7% agar. Principal component analysis was performed using four shoot growth characters (shoot length, leaf number, leaf length and callus diameter) after six-week culture. The first principal component scores indicated a size factor, because the shoot, leaf and callus grew better with increases in the score. Eighty-two cultivars and three species, D. lotus, D. japonica and D. virginiana (female plant), had -1.0 or more of the first principal component scores and maintained good shoot growth through three subcultures. Ten cultivars and D. oleifera had -1.0 or more of the score; however, these were not established because of an inadequency of subculture medium. Established explants were obtained from 102 cultivars and three species. The cultivars of three fruit types, pollination constant and non-astringent (PCNA), pollination variant and non-astringent (PVNA) and pollination variant and astringent (PVA), had less shoot elongation. Shoot growth in shoot tip culture had no relation to tree vigor and earliness of sprouting time.

Changes in Tannin Cell Morphology with Growth and Development of Japanese Persimmon Fruit

Abstract Morphological changes in tannin cells were observed in ‘Fuyu’ [pollination-constant and nonastringent (PCNA)] and ‘Hiratanenashi’ [pollination-variant and astringent (PVA)], two of the four types of Japanese persimmon fruit (Diospyros kaki L.). Pores in the tannin cell walls of ‘Fuyu’ started to occlude on 24 July when cell enlargement had ceased. This occlusion coincided with cessation of tannin accumulation, as determined by soluble tannin content and fresh weight of fruit. The pores were almost completely occluded on 7 Aug. Pore occlusion preceded the coagulation of tannins. In ‘Hiratanenashi’, pores in the tannin cell walls expanded until 7 Aug. When enlargement of tannin cells ceased on 14 Aug., occlusion of the pores in the cell walls was initiated. This event also nearly coincided with cessation of tannin accumulation. The process of occlusion was much slower than in ‘Fuyu’ and was about complete on 16 Oct. Thus, the pores in the tannin cell walls appear to be involved in tannin accumulation.

Morphological Characteristics of Tannin Cells in Japanese Persimmon Fruit

Abstract Tannin cells from fruit of Japanese persimmon (Diospyros kaki L.) cvs. Fuyu [pollination-constant and nonastringent (PCNA)], Chokenji [pollination-variant and nonastringent (PVNA)], Hiratanenashi [pollination-variant and astringent (PVA)], and Kuramitsu [pollination-constant and astringent (PCA)], were observed by florescence microscope (FM) and scanning electron microscope (SEM) on 4 July, when all cultivars were very astringent, and on 5 Sept., when ‘Fuyu’ and ‘Chokenji’ fruit had completely lost their astringency. ‘Hiratanenashi’ and ‘Kuramitsu’ fruit, however, were still quite astringent on the latter date. FM observations on 4 July indicated that tannin cells of all fruit possessed some discontinuous portions in the cell walls. SEM observations of fractured surfaces of fruit flesh verified the existence of pores in the tannin cell walls. Moreover, coagulated internal contents of tannin cells (caused by the fixatives) had protruded through the pores. On 5 Sept., however, the pores in tannin cell walls of ‘Fuyu’ and ‘Chokenji’ were not present, and the surface of coagulated internal contents had become smooth. ‘Hiratanenashi’ and ‘Kuramitsu’ fruit on 5 Sept. showed little change in the structure from that observed on 4 July. Pore occlusion occurred in ‘Hiratanenashi’ fruit that were treated on the tree with ethanol fumes to remove astringency, which indicates that loss of astringency induces structural changes in tannin cell walls.