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Developing varieties with diverse features that satisfy varied commercial needs, improving overall fruit quality, and quickly releasing them, are prerequisites in citrus breeding. However, these three goals require trade-offs in conventional breeding, even with the application of the marker-assisted selection technique. Conventional breeding cannot...
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... suggests that it could be difficult to obtain hybrids from tachibana seeds [47]. Differences between three tachibana strains and their offspring were observed in many traits, including fruit size, rind and flesh color, and rind thickness (Figure 7 and Figure S5). These differences are more evident than those observed between Kishu, Kunembo, Kaikoukan, and their offspring (Figures 3-7), which may explain why these four varieties have not been recognized as tachibana hybrids. ...
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... It has some biological characteristics, such as a long juvenile period, polyembryony, self-incompatibility, and male sterility, that make traditional crossbreeding difficult [1]. Therefore, the development and utilization of natural hybrids or bud mutation varieties have become common breeding methods [2,3]. Yuanjiangcounty is one of the important medicinal citrus production bases in China. ...
The citrus cultivar ‘Local Juhong’, which has historically been used as a traditional Chinese medicinal material, originated in Yuanjiang County, Hunan Province.Its parental type and genetic background are indistinct as of yet. Morphological observation shows that ‘Local Juhong’ has a slight oblateness in fruit shape, a relatively smooth pericarp, a fine and slightly raised oil vacuole, and an inward concave at the blossom end. The tree form and fruit and leaf morphology of ‘Local Juhong’ are similar to those of ‘Huangpi’ sour orange. To reveal the genetic background of ‘Local Juhong’, 21 citrus accessions were evaluated using nuclear and chloroplast SSR markers and whole-genome SNP information. ‘Local Juhong’ was grouped with mandarins and sub-grouped with ‘Miyagawa Wase’ and ‘Yanxi Wanlu’ in a nuclear SSR analysis, which indicated that its pollen parent might be mandarins. It was closely clustered with orange and pummelo in the chloroplast SSR analysis. The genomic sequence similarity rate of ‘Local Juhong’ with mandarin and pummelo heterozygosity was 70.88%; the main part was the heterozygosity, except for the unknown (19.66%), mandarin (8.73%), and pummelo (3.9%) parts. Thus, ‘Local Juhong’ may be an F1 hybrid with pummelo as the female parent and mandarin as the male parent, sharing sisterhood with ‘Huangpi’ sour orange.
... In this context, the high-quality citrus cultivars 'Asumi' and 'Asuki', developed by crossbreeding the seedless, male sterile cultivars 'Okitsu 46-gu' and 'Harumi' at the National Institute of Fruit Tree Science in Japan, have been introduced and cultivated by domestic farmers in South Korea. However, distinguishing between these two cultivars morphologically at the seedling stage is difficult [20][21][22][23]. They can only be primarily distinguished based on differences in their key fruit characteristics at the mature stage. ...
This study discusses the challenge of distinguishing between two high-quality mandarin cultivars, ‘Asumi’ and ‘Asuki’, which have been introduced and cultivated in Korea after being developed through crossbreeding in Japan. Owing to genetic similarities resulting from crossbreeding between the same parent cultivars, it is challenging to differentiate them morphologically at the seedling stage. This difficulty poses challenges for cultivation and harvesting on farms. To address this issue, we developed a method using sequence characteristic amplification region (SCAR) markers for rapid and accurate differentiation between the two cultivars. We selected specific primer sets from random amplified polymorphic DNA–SCAR combinations and sequence-related amplified polymorphism contrast markers. The multiplex PCR system using these molecular markers was able to identify 16 mandarin cultivars, including ‘Asumi’ and ‘Asuki’, among 30 cultivars. The use of these SCAR markers is expected to enhance citrus cultivation by accurately identifying mixed cultivars and facilitating proper harvest timing for citrus distribution. Additionally, the markers can help identify the genetic traits of hybrid varieties at the seedling stage.
... This trend is evident in major fruit trees, such as apples, citrus, and peaches (Cirilli et al. 2016;Duan et al. 2017;Rao et al. 2021). Because the selected traits are valuable for future fruit tree breeding, it is important to elucidate the genetic factors involved in the selection process (Minamikawa et al. 2017(Minamikawa et al. , 2018Cirilli et al. 2021;Shimizu 2022). ...
The Japanese apricot (Prunus mume) is a popular fruit tree in Japan. However, the genetic factors associated with fruit trait variations are poorly understood. In this study, we investigated nine fruit-associated traits, including harvesting time, fruit diameter, fruit shape, fruit weight, stone (endocarp) weight, ratio of stone weight to fruit weight, and rate of fruit gumming, using 110 Japanese apricot accessions over four years. A genome-wide association study (GWAS) was performed for these traits and strong signals were detected on chromosome 6 for harvesting time and fruit diameters. These peaks were shown to undergo strong artificial selection during the differentiation of small-fruit cultivars. The genomic region defined by the GWAS and XP-nSL analyses harbored several candidate genes associated with plant hormone regulation. Furthermore, the alleles of small-fruit cultivars in this region were shown to have genetic proximity to some Chinese cultivars of P. mume. These results indicate that the small-fruit trait originated in China; after being introduced into Japan, it was preferred and selected by the Japanese people, resulting in the differentiation of small-fruit cultivars.
... Numerous citrus varieties are being newly developed to improve citrus quality globally [11][12][13][16][17][18]. However, the quality of many of these varieties has not been objectively evaluated. ...
... The citrus metabolite profile, a crucial factor associated with the physicochemical and sensory qualities of citrus [7,27], was significantly different among the varieties (Figure 4). Carotenoid profiles are strongly correlated with citrus color [13]. High β-carotene and β-cryptoxanthin levels contributed to the orange or red color of Kiyomi, while the yellow color of Yellowball and Haruka was due to their relatively low carotenoid levels. ...
Although numerous citrus varieties have recently been developed to enhance their quality, information on their quality characteristics is limited. We assessed the quality characteristics of Yellowball, a novel citrus variety, by evaluating its appearance, storability, sensory properties, functionality, and metabolite profiles and then comparing these characteristics with those of its parent varieties, Haruka and Kiyomi. The metabolite profiles between the citrus varieties differed significantly, resulting in distinct physicochemical and functional qualities. The storability of Yellowball was significantly increased compared with that of its parent varieties owing to its strong antifungal activity and unique peel morphology, including the stoma and albedo layers. While we did not investigate the volatile compounds, overall functional activities, and detailed characteristics of each metabolite, our data provide valuable insights into the relationship between citrus metabolites, peel morphology, physicochemical properties, and storability, and demonstrate the potential of Yellowball as a promising variety in the citrus industry.
... sinensis) and a superior aroma to Satsuma (C. unshiu) [12]. Additionally, Kiyomi contributed to the development of more than 16 citrus varieties with unique features such as less rind puffing, less alternate bearing, grenadine to red rind, richness in β-cryptoxanthin, and unique fruit shape [12]. ...
... unshiu) [12]. Additionally, Kiyomi contributed to the development of more than 16 citrus varieties with unique features such as less rind puffing, less alternate bearing, grenadine to red rind, richness in β-cryptoxanthin, and unique fruit shape [12]. Conversely, the use of Haruka in citrus breeding is limited. ...
... Numerous citrus varieties are being newly developed to improve citrus quality globally [10][11][12][15][16][17]. However, the quality of many of these varieties has not been objectively evaluated. ...
Although numerous citrus varieties have recently been developed to enhance their quality, information on their quality characteristics is limited. We assessed the quality characteristics of Yellowball, a novel citrus variety, by evaluating its appearance, storability, sensory properties, functionality, and metabolite profiles and comparing these characteristics with those of its parent varieties: Haruka and Kiyomi. The metabolite profiles between the citrus varieties differed significantly, resulting in distinct physicochemical and functional qualities. The storability of Yellowball was significantly increased compared with that of its parent varieties owing to its strong antifungal activity and unique peel morphology, including the stoma and albedo layers. While we did not investigate the volatile compounds, overall functional activities, and detailed characteristics of each metabolite, our data provide valuable insights into the relationship between citrus metabolites, peel morphology, physicochemical properties, and storability and demonstrate the potential of Yellowball as a promising variety in the citrus industry.
... Elite hybrids were selected from the crossing of "Kaikoukan" and "tachibana" within a single generation. Screening of thousands and tens of thousands of offspring combining GAB techniques was assumed to be the new savior of dwindling orchards and the Citrus industry (Shimizu 2022). ...
... There are more than 1100 known cultivars of citrus fruits worldwide [28]. In addition, citrus crossbreeding is increasingly common to improve the fruit quality and develop new cultivars with novel traits [29]. Compared to the number of these citrus cultivars, the research on anti-melanogenesis is lacking. ...
Citrus is one of the most popular and widely grown fruit crops in the world. However, the bioactivity of only certain species of citrus cultivars is studied. In this study, the effects of essential oils from 21 citrus cultivars on melanogenesis were investigated in an effort to identify active anti-melanogenesis constituents. The essential oils from the peels of 21 citrus cultivars obtained by hydro-distillation were analyzed using gas chromatography–mass spectrometry. Mouse melanoma B16BL6 cells were used in all assays conducted in this study. The tyrosinase activity and melanin content were determined using the lysate of α-Melanocyte-stimulated B16BL6 cells. In addition, the melanogenic gene expression was determined by quantitative reverse transcription-polymerase chain reaction. Overall, the essential oils of (Citrus unshiu X Citrus sinensis) X Citrus reticulata, Citrus reticulata, and ((Citrus unshiu X Citrus sinensis) X Citrus reticulata) X Citrus reticulata provided the best bioactivity and comprised five distinct constituents compared to other essential oils such as limonene, farnesene, β-elemene, terpinen-4-ol, and sabinene. The anti-melanogenesis activities of the five individual compounds were evaluated. Among the five essential oils, β-elemene, farnesene, and limonene showed dominating properties. The experimental results indicated that (Citrus unshiu X Citrus sinensis) X Citrus reticulata, Citrus reticulata, and ((Citrus unshiu X Citrus sinensis) X Citrus reticulata) X Citrus reticulara are potential candidates with anti-melanogenesis activity for use as cosmetics and pharmaceutical agents against skin hyperpigmentation.
This study emphasized not only the basic concept that the sunburn of fruit was caused by fruit skin temperature rising above its tolerable threshold but also that the threshold was variable, namely, fruit became more vulnerable to sunburn on its own as the growth period progressed. These main results were derived from two major functions: first, multiple linear regression to estimate the fruit skin temperature utilizing solar radiation and ambient air temperature, and second, nonlinear regression with a sigmoid function, which represents the variability in the fruit skin temperature threshold inducing sunburn. The specific major results are as follows. Both individual and multiple regressions showed that the increase in fruit skin temperature was more affected by solar radiation than by ambient air temperature. Considering the entire period from July to September, sunburn was related to fruit skin temperatures above 46 °C. However, the specific investigation dividing the entire period into 10-day periods indicated that the fruit skin temperature threshold for inducing sunburn decreased over time. In the discriminant analysis for predicting the occurrence of sunburned fruits, the prediction accuracy based on the variable threshold was 81.9%, which was higher than 67.0% based on the fixed threshold of 46 °C. The reference ambient air temperature for the occurrence of sunburn decreased with seasonal progress in the field from higher than 35 °C in early August to 28 °C in mid-September and in the greenhouse from higher than 39 °C to 31.7 °C. The variability of thresholds related to the internal tolerance of fruit for sunburn presented the reason why sunburned fruits could occur or increase despite the weakening of abiotic factors inducing sunburn, such as solar radiation and ambient air temperature, as the season progresses from summer to autumn.
