Comparative transcriptome analysis reveals the mechanism involving ethylene and cell wall modification related genes in Diospyros kaki fruit firmness during ripening.

Rapid loss of firmness is a major handicap for persimmon (Diospyros kaki Thunb.) transportation and retail. The present study employed a comparative transcriptomic approach to elucidate the mechanism involving ethylene and cell wall modification related genes in fruit firmness control of two cultivars during post harvest ripening. In contrast to the short shelf life cultivar (Mopan), the long shelf life cultivar (Yoho) kept high firmness during ripening. Extensive loss of firmness in Mopan drove an intense transcriptional activity. Globally, Mopan and Yoho shared very few common differentially expressed structural genes and regulators. Yoho strongly repressed the expression of ACC synthase and several classes of cell wall degradation genes at the onset of ripening and only induced them during late ripening period. Various ERF, WRKY, MYB, bHLH transcription factors were found highly active during fruit ripening. Overall, this study generates novel gene resources as important tools for extending persimmon shelf life.

Epigenetic Flexibility Underlies Somaclonal Sex Conversions in Hexaploid Persimmon.

Epigenetic regulation adds a flexible layer to genetic variations, potentially enabling long-term, but reversible, changes to a trait, while maintaining genetic information. In the hexaploid Oriental persimmon (Diospyros kaki), genetically monoecious cultivars bearing male flowers require the Y-encoded small RNA (smRNA) gene, OGI. This gene represses the expression of its autosomal counterpart gene, MeGI, as part of the canonical male production system. However, a D. kaki cultivar, Saijo, which lacks the OGI gene and originally bears only female flowers, occasionally produces somaclonal mutant male and revertant female (RF) branches. In this study, we investigated the mechanisms underlying these somaclonal sex conversions in persimmon. Specifically, we aimed to unravel how a genetically female tree without the OGI gene can produce male flowers and RF flowers. Applying multi-omics approaches, we revealed that this noncanonical male production system is basically consistent with the canonical system, in which the accumulation of smRNA targeting MeGI and the considerable DNA methylation of MeGI are involved. The epigenetic status of MeGI on CGN and CHG was synchronized to the genome-wide methylation patterns, both in transition to and from the male production system. These results suggest that the somaclonal sex conversions in persimmon are driven by the genome-wide epigenetic regulatory activities. Moreover, flexibility in the epigenetic layers of long-lived plant species (e.g. trees) is important for overcoming genetic robustness.

Anti-inflammatory activities of astringent persimmons (Diospyros kaki Thunb.) stalks of various cultivar types based on the stages of maturity in the Gyeongnam province.

BACKGROUND: Natural products play a significant role in human health in relation to the prevention and treatment of inflammatory conditions. One of the plants with great medicinal potentials is Diospyros kaki which is mainly cultivated in Asian countries including Korea, Japan, and China. Astringent D. kaki is a wild species with an astringent taste until they are Ripened. kaki calyx is a traditional Korean medicine (TKM) made from the stalks of astringent D. kaki and is used in treating bed-wetting, vomiting, and hiccupping. The present study was designed to investigate the potential anti-inflammatory activities of astringent D. kaki stalks based on cultivar types and stages of maturity. METHODS: The anti-inflammatory effects of the stalk extracts of local astringent D. kaki cultivar species were evaluated on RAW 264.7 cells. Cell viability was measured using a Cell Counting Kit-8 (CCK8) method. The anti-inflammatory effects were determined by measuring the nitric oxide (NO) concentration of the supernatant. Cellular signaling pathways were determined by quantitative polymerase chain reactions of inducible nitric oxide synthase (iNOS). Protein expression of iNOS and phospho-p65 was determined using western blot, and the nuclear localization of p65 was determined using confocal imaging in RAW 264.7 cells. RESULTS: We found that the stage 1 (8-9 month) samples all showed a high percentage of tannic acid content and Gojongsi (Hamyang) stalks had the highest content. The stage 1 samples also showed the highest inhibition of NO production. Decreases in the expression of iNOS and phosphorylated p65, and in the nuclear localization of p65, were dose-dependent. All the extracts were nontoxic under 100 µg/ml concentration. CONCLUSION: This study provides insight into the changes in tannic acid content in astringent D. kaki and their anti-inflammatory effects, in relation to their stage of maturity. These results are expected to be useful in the verification of the efficacy of oriental medicine and the timing of proper harvest for medical use.

Characterization and influence of subtropical persimmon cultivars on juice and jelly characteristics

ABSTRACT To increase the availability to consumers and add more value to persimmon (Diospyros kaki L.), which is a very perishable and seasonal fruit and in order to identify which cultivars grown in subtropical regions are more suitable for processing in the form of juice and jelly, as well as understand what the consumer profile is for these products, the objective of this study was to evaluate the influence of different persimmon cultivars (Rama Forte, Mel, Guiombo and Taubaté) grown in subtropical regions of Brazil on the physicochemical characteristics, rheological properties and sensory acceptance of the resulting juice and jelly in order to identify cultivars with the greatest potential for industrial use. The different studied persimmon cultivars had different physical and physicochemical characteristics which resulted in juices and jellies with different physicochemical, rheological and sensory characteristics. Based on sensory acceptance and productivity/adaptability of persimmon crop in Brazil, the most suitable persimmon cultivars for processing are Rama Forte and Guiombo. In this study it was found that the consumer prefers a more acidic persimmon juice and a less firm or softer, less sweet, clearer and more intense yellow color persimmon jelly.

Identification of xyloglucan endotransglucosylase/hydrolase genes (XTHs) and their expression in persimmon fruit as influenced by 1-methylcyclopropene and gibberellic acid during storage at ambient temperature.

Xyloglucan endotransglucosylase/hydrolase (XTH) is thought to contribute to fruit softening by degrading xyloglucan that is a predominant hemicellulose in the cell wall. In this study, two full-length XTH genes (DKXTH1 and DKXTH2) were identified from 'Fupingjianshi' persimmon fruit, and the expression level of both XTH genes was investigated during softening for 18-24 d using RT-qPCR. Sequence analysis showed that DKXTH1 and DKXTH2 contained a putative open reading frame of 861 and 876 bp encoding polypeptides of 287 and 292 amino acid residues, respectively, which contained the conserved DEIDFEFLG motif of XTH, a potential N-linked glycosylation signal site. RT-qPCR analysis showed that DKXTH1 and DKXTH2 in untreated fruit had different expression patterns during fruit softening, in which maximum expression occurred on days 3 and 12 of ripening, respectively. 1-Methylcyclopropene (1-MCP) and gibberellic acid (GA(3)) treatments delayed the softening and ethylene peak of persimmon fruit, as well as suppressed the expression of both XTH genes, especially DKXTH1. These results indicated that the expression of both XTH genes might be ethylene dependent action, and closely related to softening of persimmon in the early (DKXTH1) and later (DKXTH2) ripening stages.

DkMyb4 is a Myb transcription factor involved in proanthocyanidin biosynthesis in persimmon fruit.

Proanthocyanidins (PAs) are secondary metabolites that contribute to the protection of the plant and also to the taste of the fruit, mainly through astringency. Persimmon (Diospyros kaki) is unique in being able to accumulate abundant PAs in the fruit flesh. Fruits of the nonastringent (NA)-type mutants lose their ability to produce PA at an early stage of fruit development, while those of the normal astringent (A) type remain rich in PA until fully ripened. The expression of many PA pathway genes was coincidentally terminated in the NA type at an early stage of fruit development. The five genes encoding the Myb transcription factor were isolated from an A-type cultivar (Kuramitsu). One of them, DkMyb4, showed an expression pattern synchronous to that of the PA pathway genes in A- and NA-type fruit flesh. The ectopic expression of DkMyb4 in kiwifruit (Actinidia deliciosa) induced PA biosynthesis but not anthocyanin biosynthesis. The suppression of DkMyb4 in persimmon calluses caused a substantial down-regulation of the PA pathway genes and PA biosynthesis. Furthermore, analysis of the DNA-binding ability of DkMyb4 showed that it directly binds to the MYBCORE cis-motif in the promoters of the some PA pathway genes. All our results indicate that DkMyb4 acts as a regulator of PA biosynthesis in persimmon and, therefore, suggest that the reduction in the DkMyb4 expression causes the NA-type-specific down-regulation of PA biosynthesis and resultant NA trait.

Engineered sorbitol accumulation induces dwarfism in Japanese persimmon.

A cDNA encoding sorbitol-6-phosphate dehydrogenase (S6PDH), which is a key enzyme in sorbitol biosynthesis in Rosaceae, was introduced into the Japanese persimmon (Diospyros kaki) to increase the environmental stress tolerance. Resultant transformants exhibited salt-tolerance with dwarfing phenotypes. Therefore, we studied two transgenic lines to understand the physiological mechanism of this dwarfism: lines PS1 and PS6 accumulated high and moderate levels of sorbitol, respectively. The average length of shoots was significantly shorter as compared with the wild-type in line PS1, while no such decrease was observed in line PS6. The myo-inositol and glucose 6-phosphate (G6P) contents were measured in the transgenic lines because previous work with tobacco transformed with S6PDH had suggested that growth inhibition was due to depletion of these metabolites. Although the myo-inositol content was decreased in PS1 plants, the decrease was much smaller than that observed in transgenic tobacco that accumulates sorbitol. The G6P contents were the same in PS1 plants and phenotypically normal PS6 plants. The level of indole-3-acetic acid (IAA), which affects stem elongation, in line PS1 was similar to the levels in the other lines. A decrease in gibberellin (GA) content generally induces dwarfism in plants. However, GA was not decreased in PS1 plants compared with wild-type or control plants. Therefore, we focused on sorbitol accumulation as the most remarkable feature of PS1 plants. As one possibility, the observed growth inhibition was likely caused by an osmotic imbalance between the cytosol and vacuole.