Japanese Society for Horticultural Science Acta Medica Okayama 2189-0102 95 1 2026 Comparison of Fruit Development, Ripening, and Transcriptome Dynamics in Taiwanese and Japanese Cultivars of Japanese Apricot (Prunus mume Sieb. et Zucc.) 10 20 EN Tomoaki Kashiwamoto Graduate School of Environmental and Life Science, Okayama University Takashi Kawai Graduate School of Environmental and Life Science, Okayama University Takaaki Oe Japanese Apricot Laboratory, Wakayama Fruit Tree Experiment Station Koji Numaguchi Japanese Apricot Laboratory, Wakayama Fruit Tree Experiment Station Yuto Kitamura Faculty of Agriculture, Setsunan University Yasutaka Kubo Graduate School of Environmental and Life Science, Okayama University Fumio Fukuda Graduate School of Environmental and Life Science, Okayama University Koichiro Ushijima Graduate School of Environmental and Life Science, Okayama University In this study, we compared changes in traits associated with fruit development and ripening in Taiwanese and Japanese cultivars of Japanese apricot (Prunus mume Sieb. et Zucc.). We also analyzed transcriptome profiles to comprehensively examine different fruit development and ripening patterns between the two groups in terms of fruit characteristics and gene expression. Early fruit development in Taiwanese cultivars ‘ST’ and ‘Ellching’ and the Japanese cultivar ‘Hakuo’ was ahead of that in other three Japanese cultivars (P1). From late April to early May, around the stone-hardening stage, the developmental differences decreased to the same level. Thereafter, Japanese cultivars showed rapid growth, whereas Taiwanese cultivars showed slower growth, reversing the developmental differences between these lines (P2). Ethylene production was not detected until the full ripening stage and was detected for the first time at this stage in five cultivars, except for ‘Ellching’ (P3). In contrast, no ethylene production was observed during the entire duration of fruit development in ‘Ellching’. A multidimensional scaling plot showed that the overall transcriptome profile changed according to the three stages (P1–P3) of fruit development and ripening. At P1, gene ontologies (GOs) related to cell division, such as the cell cycle and regulation of cyclin-dependent protein serine/threonine kinase activity, were enriched for differentially expressed genes downregulated in Taiwanese cultivars as compared with their expression in Japanese cultivars. At P2, GOs related to fruit development were not enriched, but some genes related to phytohormones, such as auxin, abscisic acid, and cytokinin, which are associated with fruit development and ripening, were differentially expressed. At P3, the expression of genes such as ACS, ACO, and PG, which are involved in ethylene biosynthesis, increased in response to increased ethylene production, but not in ‘Ellching’, which showed no ethylene production. Expression analysis of 115 NAC (NAM-ATAF1/2-CUC2) family genes, which are related to fruit ripening and ripening date in other fruit species, in the ‘Ellching’ genome revealed changes in expression of NAC056 and NAC073 corresponding to fruit development and ripening in Taiwanese and Japanese cultivars. We discuss the differences in fruit development and ripening behaviors between Taiwanese and Japanese cultivars in terms of physiological and transcriptome changes. No potential conflict of interest relevant to this article was reported.

Japanese Society for Horticultural Science Acta Medica Okayama 2189-0102 94 3 2025 Effect of Storage Temperature and a Sugar-ester Edible Coating on Postharvest Quality and Storage Life of ‘Fuyu’ Persimmon (Diospyros kaki Thunb.) 401 407 EN Maqsood Muqadas Graduate School of Environmental, Life Science, Natural Science and Technology Okayama University Oscar W. Mitalo Faculty of Life and Environmental Sciences, University of Tsukuba Kyohei Ohashi Graduate School of Environmental, Life Science, Natural Science and Technology Okayama University Takumi Otsuki Graduate School of Environmental, Life Science, Natural Science and Technology Okayama University Chikara Yano Graduate School of Environmental, Life Science, Natural Science and Technology Okayama University Ziaurrahman Hejazi Graduate School of Agriculture, University of Miyazaki Natsuki Hira Shiga R&D Center, Mitsubishi Chemical Corporation Koichiro Ushijima Graduate School of Environmental, Life Science, Natural Science and Technology Okayama University Yasutaka Kubo Graduate School of Environmental, Life Science, Natural Science and Technology Okayama University In ‘Fuyu’ persimmons (Diospyros kaki Thunb.), crunchiness is a preferred postharvest attribute among both distributors and consumers. The present study first examined softening characteristics during storage at 0, 5, 10, 15, 20, and 25°C. Fruit stored at 0°C remained firm for 84 d, while that stored at 5°C had a 100% softening rate within 35 d. At 10 and 15°C, over 70% of fruit softened within 49 d and 63 d, respectively. The softening rate was relatively slower at 20 and 25°C, with only 27% softened fruit after 56 d at 25°C. The potential of a newly developed sugar-ester (SE) edible coating to delay fruit softening and maintain postharvest quality was then assessed during storage at 0 and 25°C. Uncoated fruit stored at 0°C for 56 d developed chilling injury (CI) symptoms (rapid fruit softening and peel browning) within 2 d of rewarming at 20°C. These CI symptoms were notably mitigated in SE-coated fruit. At 25°C, SE coating also delayed fruit softening and peel color change in addition to reducing fruit shrinkage. In conclusion, in ‘Fuyu’ persimmons ambient temperature (20–25°C) storage in combination with an edible SE coating is recommended for the high demand Christmas and new year seasons and 0°C storage with an edible SE coating is suitable for longer storage and distribution. No potential conflict of interest relevant to this article was reported.

Oxford University Press (OUP) Acta Medica Okayama 1040-4651 37 7 2025 Pancentromere analysis of Allium species reveals diverse centromere positions in onion and gigantic centromeres in garlic koaf142 EN Kiyotaka Nagaki Institute of Plant Science and Resources, Okayama University Koichiro Ushijima Graduate School of Environmental and Life Science, Okayama University Takashi Akagi Graduate School of Environmental and Life Science, Okayama University Keisuke Tanaka NODAI Genome Research Center, Tokyo University of Agriculture Hisato Kobayashi NODAI Genome Research Center, Tokyo University of Agriculture In eukaryotes, centromeres interact with the kinetochore for distribution of genetic information in cell division, yet their sequence and size are diverse among species. However, their position on chromosomes is considered to be conserved within a species. In this study, we analyzed the centromeres of 3 Allium species, namely, Welsh onion (Allium fistulosum), onion (Allium cepa), and garlic (Allium sativum) via pancentromere analysis and repetitive sequence analysis of centromeres and their neighborhoods and revealed their mobility, sequence organization, and size. Among the 3 species, Welsh onion and garlic had stable centromeres, but the onion centromere appeared to be polymorphic and frequently differed in position by up to 28.0 Mb among cultivars and between multiple individuals of the same cultivar. This mobility was stabilized by hybridization with Welsh onions. Furthermore, these 3 species have very different centromere sequence organization, including differences in the existence and maturity of centromeric satellites, and differences in centromere size, with Welsh onion having a centromere of 1.9 Mb, and garlic having a centromere of ∼10.6 Mb, the largest of any organism with monocentric chromosomes analyzed to date. Our pancentromere analysis of these Allium species reveals the variation in sequence organization, size, and position of this important chromosomal region. No potential conflict of interest relevant to this article was reported.

Japanese Society of Animal Breeding and Genetics Acta Medica Okayama 1345-9961 53 1 2025 Investigation of SNPs associated with reproductive and body growth traits in Vietnamese and Nepalese native buffaloes 3 10 EN Nguyen Thuy Thanh Graduate School of Environmental and Life Science, Okayama University Tetsuo Kunieda Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Shah Manoj Kumar National Swine Research Program Le Thu Nu Anh Faculty of Animal Sciences and Veterinary Medicine, University of Agriculture and Forestry, Hue University Nguyen Van Huu Faculty of Animal Sciences and Veterinary Medicine, University of Agriculture and Forestry, Hue University Koichiro Ushijima Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Mayuko Nagae Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Takehito Tsuji Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Water buffaloes are essential to the rural economies of many developing countries, including Vietnam and Nepal, but native buffalo populations in these countries face challenges such as low productivity due to fertility and body growth issues. This study analyzed 34 SNPs in 18 genes associated with reproductive and body growth traits reported in cattle and buffalo in Vietnamese and Nepalese native buffaloes. Results showed no polymorphism at bovine SNPs in either buffalo. Further analysis with SNPs previously reported only in popular buffalo breeds, such as Murrah, found that Vietnamese buffalo were monomorphic at all sites, which may reflect reduced genetic diversity due to population decline. In contrast, Nepalese buffalo, consisting of two native breeds, showed polymorphism in 11 SNPs in 7 genes, with 10 of these matching those found in the Murrah buffalo analyzed here. These findings suggest that these SNPs may be applicable for genetic improvement in Nepalese native buffalo. This study provides valuable insights for future conservation and breeding programs aimed at enhancing reproductive and body growth performance of native buffalo in Vietnam and Nepal. No potential conflict of interest relevant to this article was reported.

Oxford University Press Acta Medica Okayama 1340-2838 30 5 2023 Genetic basis of lineage-specific evolution of fruit traits in hexaploid persimmon dsad015 EN Ayano Horiuchi Graduate School of Environmental and Life Science, Okayama University Kanae Masuda Graduate School of Environmental and Life Science, Okayama University Kenta Shirasawa Kazusa DNA Research Institute Noriyuki Onoue Institute of Fruit Tree and Tea Science, NARO Ryusuke Matsuzaki Institute of Fruit Tree and Tea Science, NARO Ryutaro Tao Graduate School of Agriculture, Kyoto University Yasutaka Kubo Graduate School of Environmental and Life Science, Okayama University Koichiro Ushijima Graduate School of Environmental and Life Science, Okayama University Takashi Akagi Graduate School of Environmental and Life Science, Okayama University Frequent polyploidization events in plants have led to the establishment of many lineage-specific traits representing each species. Little is known about the genetic bases for these specific traits in polyploids, presumably due to plant genomic complexity and their difficulties in applying genetic approaches. Hexaploid Oriental persimmon (Diospyros kaki) has evolved specific fruit characteristics, including wide variations in fruit shapes and astringency. In this study, using whole-genome diploidized/quantitative genotypes from ddRAD-Seq data of 173 persimmon cultivars, we examined their population structures and potential correlations between their structural transitions and variations in nine fruit traits. The population structures of persimmon cultivars were highly randomized and not substantially correlated with the representative fruit traits focused on in this study, except for fruit astringency. With genome-wide association analytic tools considering polyploid alleles, we identified the loci associated with the nine fruit traits; we mainly focused on fruit-shape variations, which have been numerically characterized by principal component analysis of elliptic Fourier descriptors. The genomic regions that putatively underwent selective sweep exhibited no overlap with the loci associated with these persimmon-specific fruit traits. These insights will contribute to understanding the genetic mechanisms by which fruit traits are independently established, possibly due to polyploidization events. No potential conflict of interest relevant to this article was reported.

Oxford University Press Acta Medica Okayama 0737-4038 40 7 2023 Ongoing Rapid Evolution of a Post-Y Region Revealed by Chromosome-Scale Genome Assembly of a Hexaploid Monoecious Persimmon (Diospyros kaki) msad151 EN Ayano Horiuchi Graduate School of Environmental and Life Science, Okayama University Kanae Masuda Graduate School of Environmental and Life Science, Okayama University Kenta Shirasawa Department of Frontier Research and Development, Kazusa DNA Research Institute Noriyuki Onoue Institute of Fruit Tree and Tea Science, NARO Naoko Fujita Graduate School of Environmental and Life Science, Okayama University Koichiro Ushijima Graduate School of Environmental and Life Science, Okayama University Takashi Akagi Graduate School of Environmental and Life Science, Okayama University Plants have evolved sex chromosomes independently in many lineages, and loss of separate sexes can also occur. In this study, we assembled a monoecious recently hexaploidized persimmon (Diospyros kaki), in which the Y chromosome has lost the maleness-determining function. Comparative genomic analysis of D. kaki and its dioecious relatives uncovered the evolutionary process by which the nonfunctional Y chromosome (or Y-monoecy) was derived, which involved silencing of the sex-determining gene, OGI, approximately 2 million years ago. Analyses of the entire X and Y-monoecy chromosomes suggested that D. kaki's nonfunctional male-specific region of the Y chromosome (MSY), which we call a post-MSY, has conserved some characteristics of the original functional MSY. Specifically, comparing the functional MSY in Diospyros lotus and the nonfunctional "post-MSY" in D. kaki indicated that both have been rapidly rearranged, mainly via ongoing transposable element bursts, resembling structural changes often detected in Y-linked regions, some of which can enlarge the nonrecombining regions. The recent evolution of the post-MSY (and possibly also MSYs in dioecious Diospyros species) therefore probably reflects these regions' ancestral location in a pericentromeric region, rather than the presence of male-determining genes and/or genes controlling sexually dimorphic traits. No potential conflict of interest relevant to this article was reported.

Frontiers Media SA Acta Medica Okayama 1664-462X 13 2022 Examining the Role of Low Temperature in Satsuma Mandarin Fruit Peel Degreening via Comparative Physiological and Transcriptomic Analysis 918226 EN Oscar W. Mitalo Graduate School of Environmental and Life Science, Okayama University William O. Asiche Department of Research and Development, Del Monte Kenya Ltd Seung W. Kang Graduate School of Life and Environmental Sciences, University of Tsukuba Hiroshi Ezura Graduate School of Life and Environmental Sciences, University of Tsukuba Takashi Akagi Graduate School of Environmental and Life Science, Okayama University Yasutaka Kubo Graduate School of Environmental and Life Science, Okayama University Koichiro Ushijima Graduate School of Environmental and Life Science, Okayama University Peel degreening is the most conspicuous aspect of fruit ripening in many citrus fruits because of its importance for marketability. In this study, peel degreening in response to propylene (an ethylene analog) and at varying storage temperatures was characterized in Satsuma mandarin (Citrus unshiu Marc.) fruit. Propylene treatment triggered rapid peel degreening (within 4-6 days), indicated by an increase in the citrus color index (CCI) and chlorophyll loss. Peel degreening was also observed in fruit at 10 degrees C and 15 degrees C after 28-42 days, with gradual CCI increase and chlorophyll reduction. However, fruit at 5 degrees C, 20 degrees C, and 25 degrees C remained green, and no substantial changes in peel CCI and chlorophyll content were recorded during the 42-day storage duration. The transcriptomes of peels of fruit treated with propylene for 4 days and those stored at varying temperatures for 28 days were then analyzed by RNA-Seq. We identified three categories of differentially expressed genes that were regulated by (i) propylene (and by analogy, ethylene) alone, (ii) low temperature (5 degrees C, 10 degrees C, or 15 degrees C vs. 25 degrees C) alone, and (iii) either propylene or low temperature. Gene-encoding proteins associated with chlorophyll degradation (such as CuSGR1, CuNOL, CuACD2, CuCAB2, and CuLHCB2) and a transcription factor (CuERF114) were differentially expressed by propylene or low temperature. To further examine temperature-induced pathways, we also monitored gene expression during on-tree fruit maturation vs. postharvest. The onset of on-tree peel degreening coincided with autumnal drops in field temperatures, and it was accompanied by differential expression of low temperature-regulated genes. On the contrary, genes that were exclusively regulated by propylene (such as CuCOPT1 and CuPOX-A2) displayed insignificant expression changes during on-tree peel degreening. These findings indicate that low temperatures could be involved in the fruit ripening-related peel degreening independently of ethylene. No potential conflict of interest relevant to this article was reported.

Japanese Society for Horticultural Science Acta Medica Okayama 2189-0102 91 3 2022 Deep Learning Predicts Rapid Over-softening and Shelf Life in Persimmon Fruits EN Maria Suzuki Graduate School of Environmental and Life Science, Okayama University Kanae Masuda Graduate School of Environmental and Life Science, Okayama University Hideaki Asakuma Fukuoka Agriculture and Forestry Research Center Kouki Takeshita Department of Advanced Information Technology, Kyushu University Kohei Baba Department of Advanced Information Technology, Kyushu University Yasutaka Kubo Graduate School of Environmental and Life Science, Okayama University Koichiro Ushijima Graduate School of Environmental and Life Science, Okayama University Seiichi Uchida Department of Advanced Information Technology, Kyushu University Takashi Akagi Graduate School of Environmental and Life Science, Okayama University In contrast to the progress in the research on physiological disorders relating to shelf life in fruit crops, it has been difficult to non-destructively predict their occurrence. Recent high-tech instruments have gradually enabled non-destructive predictions for various disorders in some crops, while there are still issues in terms of efficiency and costs. Here, we propose application of a deep neural network (or simply deep learning) to simple RGB images to predict a severe fruit disorder in persimmon, rapid over-softening. With 1,080 RGB images of ‘Soshu’ persimmon fruits, three convolutional neural networks (CNN) were examined to predict rapid over-softened fruits with a binary classification and the date to fruit softening. All of the examined CNN models worked successfully for binary classification of the rapid over-softened fruits and the controls with > 80% accuracy using multiple criteria. Furthermore, the prediction values (or confidence) in the binary classification were correlated to the date to fruit softening. Although the features for classification by deep learning have been thought to be in a black box by conventional standards, recent feature visualization methods (or “explainable” deep learning) has allowed identification of the relevant regions in the original images. We applied Grad-CAM, Guided backpropagation, and layer-wise relevance propagation (LRP), to find early symptoms for CNNs classification of rapid over-softened fruits. The focus on the relevant regions tended to be on color unevenness on the surface of the fruit, especially in the peripheral regions. These results suggest that deep learning frameworks could potentially provide new insights into early physiological symptoms of which researchers are unaware. No potential conflict of interest relevant to this article was reported.

Elsevier Acta Medica Okayama 09255214 174 2020 Combined signal sequence trap and macroarray analysis identifies genes associated with differential fruit softening characteristics during ripening in European and Chinese pears 111436 EN Mercy W. Mwaniki Graduate School of Environmental and Life Science, Okayama University Oscar W. Mitalo Graduate School of Environmental and Life Science, Okayama University Eric G. Mworia Graduate School of Environmental and Life Science, Okayama University Willis O. Owino Graduate School of Environmental and Life Science, Okayama University Kyoko Hiwasa-Tanase Graduate School of Life and Environmental Sciences, University of Tsukuba Jocelyn K.C. Rose Plant Biology Section, School of Integrative Plant Science, Cornell University Koh Aoki Graduate School of Life and Environmental Sciences, Osaka Prefecture University Tomoya Esumi Academic Assembly Institute of Agricultural and Life Sciences, Shimane University Takashi Kawai Graduate School of Environmental and Life Science, Okayama University Ryohei Nakano Graduate School of Environmental and Life Science, Okayama University Koichiro Ushijima Graduate School of Environmental and Life Science, Okayama University Yasutaka Kubo Graduate School of Environmental and Life Science, Okayama University During ripening, European pear (Pyrus communis L. cv. ‘La France’) fruit undergo dramatic softening in response to increased ethylene production, whereas Chinese pear (Pyrus bretschneideri Rehd. cv. ‘Yali’) fruit remain firm, despite producing large amounts of ethylene. The molecular basis of this differential softening behavior is not well understood. In this study, we combined a yeast-based signal sequence trap (YSST) and macroarray gene expression analysis to identify putative genes encoding secreted proteins that control pear fruit softening. We identified 22 cDNAs annotated as encoding proteins with diverse cell wall-associated functions that were up- or down-regulated during fruit ripening in ‘La France’. Gene expression analysis in fruit that were treated with the ethylene perception inhibitor 1-methylcyclopropene (1-MCP) at 4 d after the onset of ripening revealed that 16 of the targeted genes are ethylene-regulated, while the others appear to be ethylene independent. Comparative gene expression analyses of ‘La France’ and ‘Yali’ fruit during ripening suggested that four ethylene-regulated cDNAs encoding cell wall modifying proteins, contig 2 (polygalacturonase 3), contig 15 (expansin), contig 19 (expansin) and contig 55 (pectate lyase) contribute to the different softening behaviors of ‘La France’ and ‘Yali’ fruit. Additionally, one ethylene-independent cell wall related gene, contig 36 (expansin), and three genes encoding proteins of unknown function, contigs 1, 13 and contig 75 showed differential expression between ‘La France’ and ‘Yali’ fruit during ripening. The results presented herein represent promising candidates for future functional analysis and elucidation of softening mechanisms. No potential conflict of interest relevant to this article was reported.

Frontiers Media Acta Medica Okayama 1664-462X 11 2020 Molecular Mechanism Underlying Derepressed Male Production in Hexaploid Persimmon 567249 EN Kanae Masuda Graduate School of Environmental and Life Science, Okayama University Naoko Fujita Graduate School of Environmental and Life Science, Okayama University Ho-Wen Yang Department of Crop Sciences, University of Illinois at Urbana-Champaign Koichiro Ushijima Graduate School of Environmental and Life Science, Okayama University Yasutaka Kubo Graduate School of Environmental and Life Science, Okayama University Ryutaro Tao Graduate School of Agriculture, Kyoto University Takashi Akagi Graduate School of Environmental and Life Science, Okayama University Sex expression in plants is often flexible and contributes to the maintenance of genetic diversity within a species. In diploid persimmons (the genus Diospyros), the sexuality is controlled by the Y chromosome-encoded small-RNA gene, OGI, and its autosomal counterpart, MeGI. Hexaploid Oriental persimmon (Diospyros kaki) evolved more flexible sex expression, where genetically male individuals carrying OGI can produce both male and female flowers (monoecy). This is due to (semi-)inactivation of OGI by the Kali-SINE retrotransposon insertion on the promoter region and the resultant DNA methylations. Instead, flower sex determination in Oriental persimmon is also dependent on DNA methylation states of MeGI. Here, we focused on a cultivar, Kumemaru, which shows stable male flower production. Our results demonstrated that cv. Kumemaru carries OGI with Kali-SINE, which was highly methylated as well as in other monoecious cultivars; nevertheless, OGI gene could have a basal expression level. Transcriptomic analysis between cv. Kumemaru and 14 cultivars that predominantly produce female flowers showed differentially expressed genes (DEGs) specific to cv. Kumemaru, which is mainly involved in stress responses. Co-expression gene networks focusing on the DEGs also suggested the involvement of stress signals, mainly via gibberellin (GA), salicylic acid (SA), and especially jasmonic acid (JA) signal pathways. We also identified potential regulators of this co-expression module, represented by the TCP4 transcription factor. Furthermore, we attempted to identify cv. Kumemaru-specific transcript polymorphisms potentially contributing to derepressed OGI expression by cataloging subsequences (k-mers) in the transcriptomic reads from cv. Kumemaru and the other 14 female cultivars. Overall, although the direct genetic factor to activate OGI remains to be solved, our results implied the involvement of stress signals in the release of silenced OGI and the resultant continuous male production. No potential conflict of interest relevant to this article was reported.

Frontiers Media Acta Medica Okayama 1664-462X 11 2020 Postharvest Properties of Ultra-Late Maturing Peach Cultivars and Their Attributions to Melting Flesh (M) Locus: Re-evaluation of M Locus in Association With Flesh Texture 554158 EN Ryohei Nakano Experimental Farm of Graduate School of Agriculture, Kyoto University Takashi Kawai Graduate School of Environmental and Life Science, Okayama University Yosuke Fukamatsu Graduate School of Environmental and Life Science, Okayama University Kagari Akita Graduate School of Environmental and Life Science, Okayama University Sakine Watanabe Graduate School of Environmental and Life Science, Okayama University Takahiro Asano Graduate School of Environmental and Life Science, Okayama University Daisuke Takata Faculty of Food and Agricultural Sciences, Fukushima University Mamoru Sato Faculty of Food and Agricultural Sciences, Fukushima University Fumio Fukuda Graduate School of Environmental and Life Science, Okayama University Koichiro Ushijima Graduate School of Environmental and Life Science, Okayama University The postharvest properties of two ultra-late maturing peach cultivars, "Tobihaku" (TH) and "Daijumitsuto" (DJ), were investigated. Fruit were harvested at commercial maturity and held at 25 degrees C. TH exhibited the characteristics of normal melting flesh (MF) peach, including rapid fruit softening associated with appropriate level of endogenous ethylene production In contrast, DJ did not soften at all during 3 weeks experimental period even though considerable ethylene production was observed. Fruit of TH and DJ were treated with 5,000 ppm of propylene, an ethylene analog, continuously for 7 days. TH softened rapidly whereas DJ maintained high flesh firmness in spite of an increase in endogenous ethylene production, suggesting that DJ but not TH lacked the ability to be softened in response to endogenous and exogenous ethylene/propylene. DNA-seq analysis showed that tandem endo-polygalacturonase (endoPG) genes located at melting flesh (M) locus, Pp-endoPGM (PGM), and Pp-endoPGF (PGF), were deleted in DJ. The endoPG genes at M locus are known to control flesh texture of peach fruit, and it was suggested that the non-softening property of DJ is due to the lack of endoPG genes. On the other hand, TH possessed an unidentified M haplotype that is involved in determination of MF phenotype. Structural identification of the unknown M haplotype, designated as M-0, through comparison with previously reported M haplotypes revealed distinct differences between PGM on M-0 haplotype (PGM-M-0) and PGM on other haplotypes (PGM-M-1). Peach M haplotypes were classified into four main haplotypes: M-0 with PGM-M-0; M-1 with both PGM-M-1 and PGF; M-2 with PGM-M-1; and M-3 lacking both PGM and PGF. Re-evaluation of M locus in association with MF/non-melting flesh (NMF) phenotypes in more than 400 accessions by using whole genome shotgun sequencing data on database and/or by PCR genotyping demonstrated that M-0 haplotype was the common haplotype in MF accessions, and M-0 and M-1 haplotypes were dominant over M-2 and M-3 haplotypes and co-dominantly determined the MF trait. It was also assumed on the basis of structural comparison of M haplotypes among Prunus species that the ancestral haplotype of M-0 diverged from those of the other haplotypes before the speciation of Prunus persica. No potential conflict of interest relevant to this article was reported.

OXFORD UNIV PRESS Acta Medica Okayama 1340-2838 27 3 2020 Genome-wide study on the polysomic genetic factors conferring plasticity of flower sexuality in hexaploid persimmon dsaa012 EN Kanae Masuda Graduate School of Environmental and Life Science, Okayama University Eiji Yamamoto Kazusa DNA Research Institute Kenta Shirasawa Kazusa DNA Research Institute Noriyuki Onoue Institute of Fruit Tree and Tea Science, NARO Atsushi Kono Institute of Fruit Tree and Tea Science, NARO Koichiro Ushijima Graduate School of Environmental and Life Science, Okayama University Yasutaka Kubo Graduate School of Environmental and Life Science, Okayama University Ryutaro Tao Graduate School of Agriculture, Kyoto University Isabelle M. Henry Department of Plant Biology and Genome Center, University of California Takashi Akagi Graduate School of Environmental and Life Science, Okayama University Sexuality is one of the fundamental mechanisms that work towards maintaining genetic diversity within a species. In diploid persimmons (Diospyros spp.), separated sexuality, the presence of separate male and female individuals (dioecy), is controlled by the Y chromosome-encoded small-RNA gene, OGI. On the other hand, sexuality in hexaploid Oriental persimmon (Diospyros kaki) is more plastic, with OGI-bearing genetically male individuals, able to produce both male and female flowers (monoecy). This is thought to be linked to the partial inactivation of OGI by a retrotransposon insertion, resulting in DNA methylation of the OGI promoter region. To identify the genetic factors regulating branch sexual conversion, genome-wide correlation/association analyses were conducted using ddRAD-Seq data from an F-1 segregating population, and using both quantitative and diploidized genotypes, respectively. We found that allelic ratio at the Y-chromosomal region, including OGI, was correlated with male conversion based on quantitative genotypes, suggesting that OGI can be activated in cis in a dosage-dependent manner. Genome-wide association analysis based on diploidized genotypes, normalized for the effect of OGI allele dosage, detected three fundamental loci associated with male conversion. These loci underlie candidate genes, which could potentially act epigenetically for the activation of OGI expression. No potential conflict of interest relevant to this article was reported.

Oxford University Press Acta Medica Okayama 0022-0957 71 16 2020 Low temperature modulates natural peel degreening in lemon fruit independently of endogenous ethylene 4778 4796 EN Oscar W. Mitalo Graduate School of Environmental and Life Science, Okayama University Takumi Otsuki Graduate School of Environmental and Life Science, Okayama University Rui Okada Graduate School of Environmental and Life Science, Okayama University Saeka Obitsu Graduate School of Environmental and Life Science, Okayama University Kanae Masuda Graduate School of Environmental and Life Science, Okayama University Yuko Hojo Institute of Plant Science and Resources, Okayama University Takakazu Matsuura Institute of Plant Science and Resources, Okayama University Izumi C. Mori Institute of Plant Science and Resources, Okayama University Daigo Abe National Agriculture and Food Research Organization, Shikoku Research Station William O. Asiche Department of Research and Development, Del Monte Kenya Ltd Takashi Akagi Graduate School of Environmental and Life Science, Okayama University Yasutaka Kubo Graduate School of Environmental and Life Science, Okayama University Koichiro Ushijima Graduate School of Environmental and Life Science, Okayama University Peel degreening is an important aspect of fruit ripening in many citrus fruit, and previous studies have shown that it can be advanced by ethylene treatment or by low-temperature storage. However, the important regulators and pathways involved in natural peel degreening remain largely unknown. To determine how natural peel degreening is regulated in lemon fruit (Citrus limon), we studied transcriptome and physiochemical changes in the flavedo in response to ethylene treatment and low temperatures. Treatment with ethylene induced rapid peel degreening, which was strongly inhibited by the ethylene antagonist, 1-methylcyclopropene (1-MCP). Compared with 25 degrees C, moderately low storage temperatures of 5-20 degrees C also triggered peel degreening. Surprisingly, repeated 1-MCP treatments failed to inhibit the peel degreening induced by low temperature. Transcriptome analysis revealed that low temperature and ethylene independently regulated genes associated with chlorophyll degradation, carotenoid metabolism, photosystem proteins, phytohormone biosynthesis and signalling, and transcription factors. Peel degreening of fruit on trees occurred in association with drops in ambient temperature, and it coincided with the differential expression of low temperature-regulated genes. In contrast, genes that were uniquely regulated by ethylene showed no significant expression changes during on-tree peel degreening. Based on these findings, we hypothesize that low temperature plays a prominent role in regulating natural peel degreening independently of ethylene in citrus fruit. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 94 1 2005 バラ科植物の自家不和合性の分子機構 85 90 EN Koichiro Ushijima Self-incompatibility(GSI) in the rosaceous species is controlled by the S locus consisting of S-RNase gene and an unidentified 'pollen S' gene. A～200kbp of cosmid contig for the Sc haplotype of almond was constructed. Genomic Southern blot analyses showed that most cosmid end probes, except those near the Sc-RNase gene, cross-hybridized with DNA fragments from different S haplotypes, implying that the cosmid contig extends to the borders of the S locus. A～70kbp segment of the Sc haplotype, the S haplotype-specific region containing the S-RNase gene, was complentely sequenced. This regin was found to contain two pollen-expressed F-box genes that are likely candidates for pollen S genes. One of them, named SFB(S haplotype-specific F-Box protein), was specifically expressed in pollen, and showed high level of S haplotype-specific sequence polymorphism, comparable to that of the S-RNases. The other is unlikely to determine the S specificity of pollen, because it showed little allelic sequence polymorphism and was expressed also in pistil. Three other S haplotypes were cloned and the pollen-expressed genes were physically mapped. In all four cases, SFBs were physically linked to the S-RNase genes, and were located at the S haplotype-specific region, suggesting that the two genes are inherited as aunit. These features are consistent with the hypothrsis that SFB is the pollen S gene. This hypothesis predicts involvement of the ubiquitin/26S proteasome proteolytic pathway in the RNase-based SI system. No potential conflict of interest relevant to this article was reported.