The textural properties of grape berry flesh were evaluated with a puncture test using a total of 87 cultivars, consisting of 62 vinifera cultivars (Vitis vinifera L.) and 25 labruscana cultivars (Vitis labruscana Bailey) in order to search cultivars with crisp flesh texture for table grape breeding. Crisp texture is the most desirable texture for tableuse, and was determined as easy breakdown on mastication and firm flesh, which was measured as small deformation at the first major peak (DFP) and large maximum force (MF), respectively, in force-deformation curve of the test. For the vinifera cultivars, the mean values of DFP and MF were significantly smaller and larger in table-use cultivars than wine-use and dual-purpose cultivars, respectively. The result indicated that the vinifera wine-use and the dual-purpose cultivars had soft and non-crisp flesh. Based on the puncture tests, the cultivars with a crisp texture (2.5 mm ≥ for DFP and 0.9 N ≤ for MF) were limited to 11 vinifera table-use cultivars such as `Baladi', `Cardinal', and `Muscat of Alexandria'; and one vinifera dual-purpose cultivar (`Terbash'). The DFP was generally high in labruscana cultivars, which include table-use and dual-purpose cultivars, resulting in lacking cultivars with crisp texture among labruscana cultivars. These results indicate that the cultivars with a crisp texture were restricted to a small source within vinifera cultivars.
Akihiko Sato and Masahiko Yamada
Masahiko Yamada, Akihiko Sato and Yasuo Ukai
Environmental variance components were estimated for calyx-end fruit cracking in pollination-constant and nonastringent cultivars and selections of Japanese persimmon (Diospyros kaki Thunb.). The cracking value of a tree in a cultivar or selection (genotype) (X) was evaluated as the number of fruit that cracked divided by the total number (25) of fruit evaluated from each tree. Because the mean value of X was correlated with the variance of X, analyses of variance were performed using its square root value. The variance associated with genotyp× year interaction was the largest of environmental variance components. The variances associated among years and among trees within genotypes were very small. The mean percentage of cracked fruit in evaluation for 10 years was 3% for `Fuyu', 11% for `Matsumotowase-Fuyu', and 12% for `Izu'. On the basis of the environmental variance components obtained, it is proposed that all offspring genotypes exhibiting a phenotypic cracking incidence of less than 20% and 11% should be selected in single-year and three-year evaluations, respectively, when those genotypes are evaluated using 25 fruits from a single tree, in order to successfully select all genotypes with an genotypic incidence of less than 3%.
Akihiko Sato, Masahiko Yamada and Hiroshi Iwanami
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.
Masahiko Yamada, Hiroyasu Yamane and Yastio Ukai
Three individuals in progeny from each of 39 crosses and their parents in Japanese persimmon (Diospyros kaki Thunb.) were evaluated for fruit ripening time. Analysis of variance for the progeny, which estimated between- and within-cross variance, and the regression of the mean value in a full-sib family on the mid-parental value (MP) revealed that the genetic differences among crosses could be explained solely by MP. Genotypic values of individuals in progeny from a cross were assumed to be normally distributed around the regression line with within-cross genetic variance. Based on the parental mean performance of 3.5 fruit on a single tree for three years, the coefficient of regression of mean values in a full-sib family on MP was 0.99 ± 0.10, and the proportion of individuals in progeny having genotypic values ripening earlier than early October was estimated as 52%, 24%, and 7% for three sets of mid-parents differing in their ripening time, i.e., early, middle, and late October, respectively. On the basis of the parental mean performance in 10 fruit on a single tree without yearly repetition, the regression coefficient was estimated as 0.91 and the proportion was estimated as 44%, 20%, and 6% for the three sets of mid-parents, respectively.
Hiroko Hamada, Keisuke Nonaka, Terutaka Yoshioka and Masahiko Yamada
We estimated environmental variance components for fruit weight (FW), ease of peeling (EP), firmness of segment membrane (FSM), soluble solids content (SSC), and acidity of 20 mandarin and related cultivars used as cross-parents in citrus breeding in Japan. The variance by year was largest for FW (38% of the total) and SSC (23%), but negligible for EP, FSM, and acidity. Variance among trees and tree × year interaction were negligibly small except for FW, whereas the genotype × year interaction variance ranged from 9% to 22% of the total. Variance among fruits from the same tree was the largest environmental component for EP and FSM. Broad-sense heritability (h B 2) was 0.29 for FW, 0.52 for EP, 0.11 for FSM, 0.34 for SSC, and 0.65 for acidity in evaluations performed using single-year measurements of one tree with one fruit. Yearly repetition was more efficient than tree replication for increasing h B 2 of all traits investigated. Increasing fruit number from one to five in combination with yearly repetition also increased h B 2, especially for EP and FSM.
Ayako Ikegami, Keizo Yonemori, Akira Sugiura, Akihiko Sato and Masahiko Yamada
Japanese persimmon (Diospyros kaki Thunb.) cultivars are classified into four types depending on the nature of astringency loss of the fruit. The pollination-constant, non-astringent (PCNA) persimmons lose their astringency on the tree as the fruits develop. This PCNA trait is qualitatively inherited and recessive to the other three types, pollination-constant, astringent (PCA), pollination-variant, nonastringent (PVNA), and pollination-variant, astringent (PVA). In fact, crosses among Japanese PCNA cultivars yield only PCNA type in F1 generation as shown in recent breeding programs at the National Institute of Fruit Tree Science. Despite these previous results, we demonstrated here that non-PCNA (PVNA, PVA, and PCA) type offspring were derived at relatively high rates in the F1 generation from a cross between `Luo Tian Tian Shi', a PCNA accession from China, and the Japanese PCNA cultivar, `Taishu', despite the fact that `Luo Tian Tian Shi' was confirmed to be a true PCNA type by measuring tannin cell size, a principal morphological characteristic to distinguish PCNA cultivars from non-PCNA ones. When segregations of tannin cell size and tannin content in three progenies of the breeding populations derived from Chinese PCNA `Luo Tian Tian Shi' × Japanese PCNA `Taishu', Japanese PCNA `Shinshu' × Japanese PCNA `Taishu', and Japanese PVNA (non-PCNA) `Kurokuma' × Japanese PCNA `Taishu' were investigated, all offspring between Japanese PCNA cultivars contained only small tannin cells and were PCNA types, and those between Japanese PVNA × PCNA cultivars contained only large tannin cells and were non-PCNA types. However, hybrids between `Luo Tian Tian Shi' and `Taishu' segregated into populations of small and large tannin cells, indicating that `Luo Tian Tian Shi' is likely heterozygous for astringency. Therefore, Chinese PCNA `Luo Tian Tian Shi' should be different from Japanese PCNA cultivars in genetic makeup.
Sogo Nishio, Masahiko Yamada, Yutaka Sawamura, Norio Takada and Toshihiro Saito
The effectiveness of detected quantitative trait loci (QTLs) and molecular markers associated with them in tree fruit breeding is measured by the percentages of the variance associated with detected QTL effects accounting for not phenotypic variance, but genetic variance of the trait. The genetic variance can be obtained by subtracting environmental variance from the phenotypic variance. Once accurate environmental variance components are obtained for a given selection field, environmental variances under any number of replications and measurement repetitions can be estimated. We estimated environmental variance components of fruit ripening date measured by days in a Japanese pear (Pyrus pyrifolia Nakai) breeding field in the National Institute of Fruit Tree Science, Tsukuba, Ibaraki, Japan. We estimated variance among fruits within a tree (σf 2) as 25.6, among trees within a genotype (σt 2) as 0.2, among years (σy 2) as 9.4, associated with genotype × year interaction (σgy 2) as 7.9, and associated with tree × year interaction (σty 2) as 1.2. Because σf 2 was the largest environmental variance component, increasing the number of fruit evaluated would most effectively reduce the environmental variance, and tree replication would not because of very small σt 2 and σty 2. The 95% confidence limit of a genotypic value was ± 10 days in the evaluation of five fruits on a single tree in a year and ± 7 days over 2 years. Broad-sense heritability in a family, each offspring in which was evaluated using five fruits on a single tree in a single year, was estimated at 0.83 for three full-sib families analyzed.
Ayako Ikegami, Keizo Yonemori, Akira Kitajima, Akihiko Sato and Masahiko Yamada
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.
Shinya Kanzaki, Keizo Yonemori, Akira Sugiura, Akihiko Sato and Masahiko Yamada
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.
Naofumi Hiehata, Shinji Fukuda, Yoshihiko Sato, Yukiko Tominaga, Osamu Terai and Masahiko Yamada
Loquat canker, caused by Pseudomonas syringae pv. eriobotryae, is a serious disease of loquat [Eriobotrya japonica (Thunb.) Lindl.] in some countries such as Japan. Therefore, improved canker resistance is an important objective for loquat breeding. The resistance to loquat canker Group C in descendants of ‘Shiromogi’ was expressed only in homozygotes with a recessive gene at a single locus, which was designated pse-c/pse-c. ‘Champagne’, which is distantly related to ‘Shiromogi’, is another cultivar with resistance to Group C. The inheritance of this resistance in progenies of crosses between ‘Champagne’ and susceptible cultivars was examined. The offspring seedlings from 14 crosses between ‘Champagne’ (pse-c/pse-c) and 12 susceptible cultivars (Pse-c/Pse-c or Pse-c/pse-c) were classified into two types of resistant and susceptible. All of the hybrid progenies between ‘Champagne’ (pse-c/pse-c) and Pse-c/Pse-c parents showed two types of resistant and susceptible. The proportion of resistant offspring showed great differences significantly, depending on the hybrid combinations. It ranged from 0.203 to 0.596 with an average of 0.407. It indicated that the resistance was controlled by one or more additional genes or loci other than the Pse-c (pse-c) locus. In addition, the proportion of resistant offspring from crosses between ‘Champagne’ (pse-c/pse-c) and Pse-c/pse-c parents ranged from 0.463 to 0.701 (and averaged 0.601), which seriously deviated from the segregation of 1:1, indicating that the segregation was both Mendelian and polygenic in a threshold character. The proportion of resistant seedlings cannot be predicted by the phenotype and the genotype in the Pse-c (pse-c) locus. Therefore, the general combining ability of ‘Champagne’ resulting from the additional gene effect was estimated, which was 0.407 and 0.101 for ‘Champagne’ × Pse-c/Pse-c and ‘Champagne’ × Pse-c/pse-c cultivars, respectively. The gene effect of susceptible cultivars ranged from –0.204 (‘Yougyoku’) to +0.189 (‘Togoshi’) for ‘Champagne’ × Pse-c/Pse-c cultivars and from –0.138 (‘Taisho’) to +0.089 (‘Nagasakiwase’) for ‘Champagne’ × Pse-c/pse-c cultivars.