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  • Author or Editor: Akihiko Sato x
  • Journal of the American Society for Horticultural Science x
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Berry texture of grapes (Vitis labruscana Bailey, V. vinifera L., and their hybrids) can be characterized by two factors: 1) difficulty of breakdown in mastication and 2) firmness, which can be mechanically measured as deformation at first major peak (DFP) and maximum force (MF) of the force-deformation curve in flesh puncture tests. Crisp texture (easily breakable and firm flesh texture), one of the most important factors for the quality of table grapes, corresponds to a combination of small DFP (≤2.5 mm) and large MF (≥0.9 N). Obtaining offspring with crispy flesh is a primary objective in grape interspecific hybrid breeding at the National Institute of Fruit Tree Science, Japan. In this study, the expected proportion (EP) of offspring with crispy flesh as a genotypic value was estimated using a population consisting of 23 full-sib families each with eight offspring. An analysis of variance in the offspring, which estimated between-family and within-family variances, and the regression analysis of the family mean (Fm) of eight offspring in each full-sib family on mid-parental value (MP) were conducted for DFP and MF. The results revealed that the total genetic variation in offspring was mostly explained by the variance due to the regression and the within-family variance for both DFP and MF. No significant heterogeneity of within-family variance was detected by Bartlett's test for either DFP or MF. Therefore, a simple model was used to calculate EP: Fm is solely determined by the regression of Fm on MP, and all families have an equal within-family genetic variance due to segregation. Since merely a weak correlation relationship existed between DFP and MF, its influence was omitted in calculating EP. The EP of offspring having crisp texture was estimated to be 11% for an MP value of DFP of 2.5 mm (DFP for `Italia'), 6% for a DFP of 3.5 mm (DFP for `Athens'), and 3% for a DFP of 4.5 mm (DFP for `Bath'); the MP value of MF was assumed to be 0.7 N (MF for `Steuben' and `Italia') in this calculation.

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Expression patterns of the genes involved in condensed tannin (CT) biosynthesis during fruit development was investigated in a Chinese pollination-constant, nonastringent (PCNA) persimmon (Diospyros kaki Thunb.) `Luo Tian Tian Shi'. The transcript levels of phenylalanine ammonia-lyase (PAL) and dihydroflavonol reductase (DFR) in `Luo Tian Tian Shi' were detected at high levels throughout the fruit growth. Chalcone synthase (CHS) and flavonol 3-hydroxylase (F3H) also continued to be transcribed during fruit growth, although their levels decreased earlier than PAL and DFR. In contrast, expression levels of these genes declined into undetectable levels at an early stage of fruit development in Japanese PCNA persimmon. In addition, anthocyanidin reductase (ANR), which encodes a key enzyme of the proanthocyanidin biosynthesis, was transcribed at high levels in `Luo Tian Tian Shi' during fruit growth, but not in Japanese PCNA persimmon. By contrast, the expression of D. kaki serine carboxypeptidase-like protein 1 (DkSCPL1) that was obtained from suppression subtractive hybridization (SSH) analysis between artificially astringency-removed fruit and astringent fruit in a different experiment, declined earlier than the other flavonoid biosynthesis genes in `Luo Tian Tian Shi', coincident with the termination of the tannin cell development. In the F1 progeny of the cross between `Luo Tian Tian Shi' and Japanese PCNA `Taishu', similar expression patterns were obtained among segregated PCNA and astringent offspring. These results indicate that Chinese PCNA is different from Japanese PCNA in expression of the genes involved in CT biosynthesis. In conclusion, we clarified that expression of the genes (PAL to ANR, but not SCPL) involved in flavonoid biosynthesis was continuous in the Chinese PCNA cultivar, despite the termination of tannin cell development.

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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.

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