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 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.

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.

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 2186-7755 105 2016 大学生の朝食欠食習慣の統計解析と改善への新指針 1 5 EN T. Tamura T. Ibi K. Inagaki Y. Kubo K. Okuda This study investigated the current status and causes underneath the life of university students who tend to lack breakfast at a relatively high frequency, and statistical analysis on consequences leading to such lack of well-nourished eating habitat in their university life. In October 2014, self-assessed questionnaires were administered to over 150 faculty students. It contained questions about breakfast habits, time allowance for the morning class, and lunchtime setting in their high school timetable. Breakfast states were clearly separated in three groups : 68% of students regularly have breakfast throughout the weekdays, 21% students skipping the breakfast occasionally, and 11% student no habit for breakfast at all. The survey on the high school lives revealed that 70% students used to have lunch 30 min later than the lunchtime set in the university timetable, 7% of them had the lunch time even more than 1 h later. Lunchtime varies among high schools, and statistical significance was revealed (p<0.01) that schools with higher deviation scores tend have late lunch beyond 12: 30. Accordingly, university students were given directions to prepare for the timetable reform on postulation of having lunch time over one o’clock. After continuous survey on the breakfast habits during the second semester, more than 90% of students established the habit of breakfast regularly in their university lives with the improved consciousness toward well-balanced healthy breakfast contents for their higher level of education quality. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 84 1 1995 トマト果実のグルタミン酸蓄積とエチレンの関係 31 35 EN Akitsugu Inaba Akira Nakatsuka Yasutaka Kubo Reinosuke Nakamura The effect of ethylene on the accumulation of glutamate in the fruit of normal tomato ('Rutgers' and 'Momotaro')and ripening inhibitor mutant (rin) tomato(Lycopersicon esculentum Mill.) during ripening was investigated.As fruit ripening progresse,glutamate content in the fruit pericarp tissue increased greatly in 'Rutgers' but remained low and constant level in rin tomato.Glutamine and γ-aminobutyric acid contents decreased gradually during ripening in both 'Rutgers'and rin fruit.Relatively high activities of glutamate dehydrogease,glutamate synthase and glutamine synthetase were detected throughout fruit ripening in both varieties,whereas no relationship was observed between glutamate content and the enzyme activieies.Treatment of 'Momotaro'fruit with diazocyclopentadience,an inhibitro of ethylene action,inhibited the increase in ethylene production and glutamate accumlation which are associated with fruit ripening,suggesting that glutamate accumlation may be mediated through ethylene.However,glumamate content in rin fruit treatde with exogenous ethylene remained low and unchanged uitil after four days.The results indicate that accumulation of glutamete in tomato fruit is likely to be related to the ripening process apart from the direct role of ethylene. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 86 1 1997 チュウゴクナシ‘鴨梨’果実の軟化と細胞壁多糖類およびその分解酵素活性 71 78 EN Bo Ning Yasutaka Kubo Akitsugu Inaba Reinosuke Nakamura The softening characteristics of Chinese pear 'Yali'fruit,based on changes in the rates of respiration and ethylene production,flesh hardness,the content of cell-wall polysacchairides and the activities of their degraging enzymes were determined,in comparison with Japanese pear 'Nijisseiki' and European pears 'la France' and 'Bartlett'.Rates of respiration and ethylene production in 'Yali','la France' and 'Bartlett' fruits increaced with the advance of ripening,showing the most significiant increase of ethylene production in 'Yali' fuit.Decrease of flesh hardness during ripening was rapid in 'la France' and 'Bartlett' fruits,but slow in 'Yali' and 'Nijisseiki' fruits.Though rapid increase of pectinmethylesterase activity in 'la France' and 'Bartlett' fruits was observed with concomitant decrease of hardness,the same activity was maintained at a lower level in 'Yali' and 'Nijissiki' fruits.Increase in polygalacturonase activity during ripening was rapid in 'la France' and 'Bartlett' fruits,Cellulase activity increased with the decrease in flesh hardness in 'la France' and 'Yali' fruits,whereas its increase was slight during ripenig in 'Nijisseiki' and 'Bartlett' fruits.Increase in the content of hydrochloride-soluble pectin during flesh softening were very slight in 'Yali' and 'Nijisseiki' fruits in contrast with their marked evidence in 'la France' and 'Bartlett' furits.From the results obtained above,its seemes that long-term hardness maintenance in Chinese pear 'Yali' fruit during ripenig was due to lower activity by degrading enzymes of cell-wall polysaccharides,compared with those in other pear fruits. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 86 1 1997 湿度条件に対する青果物の生理反応の類型 61 69 EN Yanbin Xue Yasutaka Kubo Akitsugu Inaba Reinosuke Nakamura In this paper,effects of relative humidity(RH)on the respiration rate and ethylene production of 63 kinds of fruits and vegetables including flowres were investigated at diffrent humidities of high RH (93-98%)and low RH(52-65%).From the respiratory response to RH,they could be classified into three groups:accelerative,inhibitive and insensitive low RH.The first group included climacteric fruits such as banana,pear and kiwifruit;the majority of the fruit vegetables;and root vegetables such as tap root,tuber and tuberous root.The second group included Chinese pear,Japanese pear,strawberry,the majority of the leaf vegetables,mushrooms and flowres.The third group included grape and orange.Furthermore,by appending endogenous ethylene production at low RH,they could be classified into eight goups from the physiological response to low RH.These results seem to indicate that water deficit stress at low RH was positively correlated their physiology response in secondary order. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 90 1 2001 Structural Characterization of ACC Synthase Genes from Melon and Cucumber and their Promoter Activities Determined by GUS Transient Assay 27 35 EN Shinjiro Shiomi Ogura Emi Mikihiro Yamamoto Reinosuke Nakamura Yasutaka Kubo Akitsugu Inaba In orader to clarify the differences in regulatory mechanism(s) of the expression of 1-aminocyclopropane-1-carboxylate(ACC) synthase(ACS)genes during ripening in climacteric melon fruit and non-climacteric cucumber fruit, two sets of their genomic DNA sequences, including ca. 2kb of the promoter regions were determined, using PCR-based methods. ACS genes from melon (CMe-ACS1,2) were structurally similar to their counterpart from cucumber (CS-ACS1,2) in terms of size and position of exons and introns, restriction map, and sequencd identity of exeons, introns, proximal 5'-flanking promoter regions and splice junction. Southern blot analysis indicated that each ACS gene is present as a single copy. Transient promoter activity was investigated with two constructs of promoter-β-glucuronidase (GUS) fusion, CMe-ACS1:GUS and CS-ACS1:GUS, in mature mesocarp tissue of the two fruits. In melon disks, GUS activities conferred by the promoters of both CS-ACS1 (-2098～+42) and CMe-ACS-1(-2187～+67) were detected, which were decreased by treatment with 1-methylcyclopropene(1-MCP), an ethylene action inhibitor. In cucumber disks, however, only CS-ACS1:GUS was expressed; the activity was decreased with 1-MCP, and it was not affected by propylene. These results suggest that the promoter of CS-ACS1 has a potential to be expressed in the mesocarp tissue of ripening melon fruit, and that the difference in ethylene biosynthesis between melon and cucumber during ripening may be due to the difference in capability of forming trans-acting factor(s), not due to their ACS1 promoter activities. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 82 1 1993 Partial Characterization of 1-Aminocyclopropane-1-carboxylate　Oxidase from Excised Mesocarp Tissue of Winter Squash Fruit 49 59 EN Francis Mutiso Mathooko Yasutaka Kubo Akitsugu Inaba Reinosuke Nakamura 1-Aminocyclopropane-1-carboxylate (ACC) oxidase, the enzyme that catalyzes the conversion of ACC to ethylene, the final step of ethylene biosynthesis was extracted from wounded mesocarp tissue of winter squash (Cucurbita maxima Duch. v. Ebisu) fruit. The enzyme was characterized with respect to temperature optima, thermostability, stability in the presence f selected metal ions and alkylating agents, and Km value for ACC. 　　ACC oxidase requires Fe2+ as a co-factor and maximum activity was achieved using Fe2+ at 20uM in the reaction mixture. The enzyme was activated by C02 and inclusion of C02 in the reaction mixture increased the apparent Km value of the enzyme with respect to ACC. The enzyme exhibited apparent Km values for ACC of 147uM in air and 454 uM in the presence of 5 % C02. ACC oxidase was partially inactivated by ACC during its catalytic action. The enzyme had maximum activity at 30℃ and its activity was almost completely lost m the presence of Ag+, C02+, Cu2+ and Zn2+ ions. The alkylating agents, iodoacetamide and iodoacetic acid partially inhibited and almost completely abolished ACC oxidase activity respectively, thereby suggesting requirement of sulfhydryl groups for ACC oxidase activity. Following excision of the mesocarp tissue, the increase in in vivo ACC oxidase activity was accompanied by a concomitant increase in in vitro ACC oxidase activity. 　The results support and extend previous observations and indicate that the solubilized enzyme is indeed ACC oxidase and resembles the physiological ACC oxidase in several aspects. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 73 1 1989 高濃度炭酸ガスと低濃度酸素条件が青果物の呼吸活性に及ぼす影響 27 33 EN Yasutaka Kubo Akitsugu Inaba Hidenobu Kiyasu Reinosuke Nakamura 高CO2+低O2環境での各種青果物のO2吸収量を自作のコンピュータ制御自動呼吸計測装置を用いて測定した.トウモロコシとモモでは,それぞれ80 % CO2+20 % Airと90 % CO2+10 % Air下で,空気下と比較して呼吸活性が顕著に抑制された.キュウリとウンシュウミカンでも高CO2+Air条件による呼吸活性の抑制がみられた.カキと緑熟バナナでは,80 % CO2+20 % Airによる呼吸活性の抑制はほとんどみられなかった.一方,レタスとホウレンソウでは高CO2処理により,逆に呼吸活性が徐々に促進された. O2濃度を20 % に保った状態で60 % CO2処理すると,ウンシュウミカンでは呼吸活性の抑制はみられなくなったが,レタスでは呼吸活性がやはり促進された.これらのことから,従来から考えられている高CO2の呼吸抑制作用には疑問があるように思われた. 25 ℃ では高CO2+Air処理によって呼吸活性が変動する青果物でも,15 ℃ 以下の温度では変動しない場合が多かった.したがって,ガス環境に対する青果物の反応は温度依存性を持つように思われた。 No potential conflict of interest relevant to this article was reported.