Japanese Society of Breeding Acta Medica Okayama 1344-7610 75 3 2025 Polyphyletic domestication and inter-lineage hybridization magnified genetic diversity of cultivated melon, Cucumis melo L. 168 178 EN Katsunori Tanaka Faculty of Agriculture and Life Science, Hirosaki University Gentaro Shigita Graduate School of Environmental and Life Science, Okayama University Tran Phuong Dung Graduate School of Environmental and Life Science, Okayama University Phan Thi Phuong Nhi University of Agriculture and Forestry, Hue University Mami Takahashi Graduate School of Environmental and Life Science, Okayama University Yuki Monden Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Hidetaka Nishida Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Ryuji Ishikawa Faculty of Agriculture and Life Science, Hirosaki University Kenji Kato Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Melon accessions with diverse geographical origins were classified into large and small seed-types by length of seed at the boundary of 9 mm, and into five populations based on polymorphisms in the nuclear genome. They were further divided into three maternal lineages, Ia, Ib, and Ic, by polymorphisms in the chloroplast genome. By combining these three classifications, the Europe/US subsp. melo and the East Asian subsp. agrestis were characterized as [large seed, Ib, PopA1 or A2] and [small seed, Ia, PopB1 or B2], respectively, indicating nearly perfect divergence. In South Asia, in addition to the Europe/US and East Asian types, recombinant types between the two types were detected and accounted for 34.8% of South Asian melon. The finding of such an intermixed structure of genetic variation supported the Indian origin of Ia and Ib types. As to Momordica popular in South Asia, seed length was intermediate between the large and small seed-types, and chloroplast type was a mixture of Ia and Ib, suggesting its origin from the recombinant type. In Africa, three lineages of melon were distributed allopatrically and showed distinct divergence. Subsp. agrestis of the Ic type proved to be endemic to Africa, indicating its African origin. No potential conflict of interest relevant to this article was reported.

Oxford University Press (OUP) Acta Medica Okayama 0305-7364 135 7 2025 Molecular polymorphisms of the nuclear and chloroplast genomes among African melon germplasms reveal abundant and unique genetic diversity, especially in Sudan 1329 1343 EN Odirichi Nnennaya Imoh Graduate School of Environmental and Life Science, Okayama University Gentaro Shigita Graduate School of Environmental and Life Science, Okayama University Mitsuhiro Sugiyama Institute of Vegetable and Floriculture Science, National Agriculture and Food Research Organization (NARO) Tran Phuong Dung Graduate School of Environmental and Life Science, Okayama University Katsunori Tanaka Faculty of Agriculture and Life Science, Hirosaki University Mami Takahashi Graduate School of Environmental and Life Science, Okayama University Kazusa Nishimura Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Yuki Monden Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Hidetaka Nishida Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Mashaer Goda Plant Genetic Resources Conservation and Research Center, Agricultural Research Corporation Michel Pitrat INRAE, UR1052, Génétique et amélioration des fruits et légumes Kenji Kato Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Background and Aims Africa is rich in wild species of Cucumis and is considered one of the places of origin of melon. However, our knowledge of African melon is limited, and genetic studies using melon germplasms with wide geographical coverage are required. Here, we analysed the genetic structure of African melons, with emphasis on Sudan.<br> Methods Ninety-seven accessions of African melon were examined along with 77 reference accessions representing Asian melon and major horticultural groups. Molecular polymorphisms in the nuclear and chloroplast genomes were investigated using 12 RAPD, 7 SSR and 3 SNP markers. Horticultural traits, including seed size, were measured for 46 accessions, mainly from Sudan.<br> Key Results African melons were divided into large and small seed-types based on seed length: large seed-type from Northern Africa and small seed-type from Western and Southern Africa. Both seed types are common in Sudan. Molecular genetic diversity in these geographical populations was as high as in India, the Asian centre of melon domestication. Large seed-types from Northern Africa were assigned to Pop4 by structure analysis and had Ib cytoplasm in common with Cantalupensis, Inodorus and Flexuosus. Small seed-types were highly diversified and geographically differentiated; specifically, Pop1 with Ia cytoplasm in Southern Africa and South Asia, Pop2 with Ia in East Asia, including Conomon and Makuwa, and Pop3 with Ia or Ic in Africa. Sudanese small seed-types were grouped in Pop3, while their cytoplasm type was a mixture of Ia and Ic. Sudanese Tibish had Ic cytoplasm, which was unique in Africa, common in Western Africa and Sudan, and also found in wild or feral types.<br> Conclusions Melon of Ic lineage, including Tibish, originated from wild melon in the ewestern Sudan regionf, and independently of melon with Ia or Ib cytoplasm, which originated in Asia. This clearly indicates the polyphyletic origin of melon. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 0925-9864 71 3 2023 Analysis of genetic diversity and population structure in Cambodian melon landraces using molecular markers 1067 1083 EN Pervin Mst Naznin Graduate School of Environmental and Life Science, Okayama University Odirichi Nnennaya Imoh Graduate School of Environmental and Life Science, Okayama University Katsunori Tanaka Faculty of Agriculture and Life Science, Hirosaki University Ouch Sreynech Cambodian Agricultural Research and Development Institute Gentaro Shigita Department of Life Science Systems, Technical University of Munich Yon Sophea Cambodian Agricultural Research and Development Institute Sakhan Sophany Cambodian Agricultural Research and Development Institute Ouk Makara Plant Breeder, Retired Director of the Cambodian Agricultural Research and Development Institute Norihiko Tomooka Research Center of Genetic Resources, National Agriculture and Food Research Organization (NARO) Yuki Monden Graduate School of Environmental and Life Science, Okayama University Hidetaka Nishida Graduate School of Environmental and Life Science, Okayama University Kenji Kato Graduate School of Environmental and Life Science, Okayama University Genetic diversity of Cambodian melons was evaluated by the analysis of 12 random amplified polymorphic DNA (RAPD) and 7 simple sequence repeat (SSR) markers using 62 accessions of melon landraces and compared with 231 accessions from other areas for genetic characterization of Cambodian melons. Among 62 accessions, 56 accessions were morphologically classified as small-seed type with seed lengths shorter than 9 mm, as in the horticultural groups Conomon and Makuwa. Gene diversity of Cambodian melons was 0.228, which was equivalent to those of the groups Conomon and Makuwa and smaller than those of Vietnamese and Central Asian landraces. A phylogenetic tree constructed from a genetic distance matrix classified 293 accessions into three major clusters. Small-seed type accessions from East and Southeast Asia formed clusters I and II, which were distantly related with cluster III consisting of large-seed type melon from other areas. All Cambodian melons belonged to cluster I (except three accessions) along with those from Thailand, Myanmar, Yunnan (China), and Vietnam (gDua thomh in the northwest), thus indicating genetic similarity in these areas. In addition, the Cambodian melons were not differentiated among geographical populations. Conomon and Makuwa were classified into cluster II, together with melon groups from the plains of Vietnam. The presence of two groups of melons in Southeast Asia was also indicated by population structure and principal coordinate analysis. These results indicated a close genetic relationship between Cambodia and the neighboring countries, thus suggesting that Cambodian melons are not directly related to the establishment of Conomon and Makuwa. No potential conflict of interest relevant to this article was reported.

Japanese Society of Breeding Acta Medica Okayama 1344-7610 73 3 2023 Elucidation of genetic variation and population structure of melon genetic resources in the NARO Genebank, and construction of the World Melon Core Collection 269 277 EN Gentaro Shigita Graduate School of Environmental and Life Science, Okayama University Tran Phuong Dung Graduate School of Environmental and Life Science, Okayama University Mst. Naznin Pervin Graduate School of Environmental and Life Science, Okayama University Thanh-Thuy Duong Graduate School of Environmental and Life Science, Okayama University Odirich Nnennaya Imoh Graduate School of Environmental and Life Science, Okayama University Yuki Monden Graduate School of Environmental and Life Science, Okayama University Hidetaka Nishida Graduate School of Environmental and Life Science, Okayama University Katsunori Tanaka Faculty of Agriculture and Life Science, Hirosaki University Mitsuhiro Sugiyama Institute of Vegetable and Floriculture Science, National Agriculture and Food Research Organization (NARO) Yoichi Kawazu Institute of Vegetable and Floriculture Science, National Agriculture and Food Research Organization (NARO) Norihiko Tomooka Research Center of Genetic Resources, National Agriculture and Food Research Organization (NARO) Kenji Kato Graduate School of Environmental and Life Science, Okayama University Numerous genetic resources of major crops have been introduced from around the world and deposited in Japanese National Agriculture and Food Research Organization (NARO) Genebank. Understanding their genetic variation and selecting a representative subset (gcore collectionh) are essential for optimal management and efficient use of genetic resources. In this study, we conducted genotyping-by-sequencing (GBS) to characterize the genetic relationships and population structure in 755 accessions of melon genetic resources. The GBS identified 39,324 single-nucleotide polymorphisms (SNPs) that are distributed throughout the melon genome with high density (one SNP/10.6 kb). The phylogenetic relationships and population structure inferred using this SNP dataset are highly associated with the cytoplasm type and geographical origin. Our results strongly support the recent hypothesis that cultivated melon was established in Africa and India through multiple independent domestication events. Finally, we constructed a World Melon Core Collection that covers at least 82% of the genetic diversity and has a wide range of geographical origins and fruit morphology. The genome-wide SNP dataset, phylogenetic relationships, population structure, and the core collection provided in this study should largely contribute to genetic research, breeding, and genetic resource preservation in melon. No potential conflict of interest relevant to this article was reported.

‰ͺŽR‘εŠw”_Šw•” Acta Medica Okayama 2186-7755 105 2016 Molecular-based analysis of genetic diversity and classification of Japanese melon breeding lines 7 15 EN Tran Phuong Dung Katsunori Tanaka Yukari Akashi Duong Thanh Thuy Hidetaka Nishida Kenji Kato For the breeding of Japanese netted melon, various types of foreign cultivars have been utilized for improving adaptability, disease and pest resistance, fruit quality and so on. However, little is known about their genetic diversity and relationships, since most cultivars derived from crosses between various horticultural groups. To figure out the genetic structure of Japanese melon, in this study, 57 melon accessions from three horticultural groups were examined using 55 RAPD markers produced by 24 RAPD primers. Genetic diversity of the Japanese netted melon was as high as those of cultivar groups of Groups Cantalupensis and Inodorus, while it was low in Group Conomon irrespective of large variations in fruit traits. Cluster analysis and PCO analysis based on genetic distance showed that Group Conomon was distantly related to other melon accessions. Among the latter, European cantaloupe (nonnetted) and American open-field type (netted) proved to be genetically close, while England glasshouse melon (netted) including eEarlfs Favouritef is distantly related to these two groups and closely related with Group Inodorus. It was therefore suggested that England glasshouse type was established from hybrids between European cantaloupe and Group Inodorus. Japanese netted melon was most closely related with England glasshouse type, irrespective of the fact that various kinds of melon accessions have been crossed to improve adaptability, disease resistance and so on. In contrast, pure line cultivars of the Japanese netted melon bred by pure line selection from eEarl's Favouritef or by crossing eEarlfs Favouritef with eBritish Queenf were confirmed to be mostly homogenous, and it was difficult to establish RAPD markers to discriminate each cultivar. Group Conomon var. makuwa and var. conomon, which have been cultivated and utilized as different crops, proved to be genetically indistinguishable and were considered to share the same gene pool. No potential conflict of interest relevant to this article was reported.

National Academy of Sciences. Acta Medica Okayama 0027-8424 112 39 2015 Identification of the VERNALIZATION 4 gene reveals the origin of spring growth habit in ancient wheats from South Asia E5401 E5410 EN Nestor Kippes Juan M. Debernardi Hans A. Vasquez-Gross Bala A. Akpinar Hikment Budak Kenji Kato Shiaoman Chao Eduard Akhunov Jorge Dubcovsky Wheat varieties with a winter growth habit require long exposures to low temperatures (vernalization) to accelerate flowering. Natural variation in four vernalization genes regulating this requirement has favored wheat adaptation to different environments. The first three genes (VRN1–VRN3) have been cloned and characterized before. Here we show that the fourth gene, VRN-D4, originated by the insertion of a ∼290-kb region from chromosome arm 5AL into the proximal region of chromosome arm 5DS. The inserted 5AL region includes a copy of VRN-A1 that carries distinctive mutations in its coding and regulatory regions. Three lines of evidence confirmed that this gene is VRN-D4: it cosegregated with VRN-D4 in a high-density mapping population; it was expressed earlier than other VRN1 genes in the absence of vernalization; and induced mutations in this gene resulted in delayed flowering. VRN-D4 was found in most accessions of the ancient subspecies Triticum aestivum ssp. sphaerococcum from South Asia. This subspecies showed a significant reduction of genetic diversity and increased genetic differentiation in the centromeric region of chromosome 5D, suggesting that VRN-D4 likely contributed to local adaptation and was favored by positive selection. Three adjacent SNPs in a regulatory region of the VRN-D4 first intron disrupt the binding of GLYCINE-RICH RNA-BINDING PROTEIN 2 (TaGRP2), a known repressor of VRN1 expression. The same SNPs were identified in VRN-A1 alleles previously associated with reduced vernalization requirement. These alleles can be used to modulate vernalization requirements and to develop wheat varieties better adapted to different or changing environments. No potential conflict of interest relevant to this article was reported.

‰ͺŽR‘εŠw–„‘ •Ά‰»ΰ’²ΈŒ€‹†ƒZƒ“ƒ^[ Acta Medica Okayama 2012 2013 ‰ͺŽR‘εŠw–„‘ •Ά‰»ΰ’²ΈŒ€‹†ƒZƒ“ƒ^[‹I—v2012 EN No potential conflict of interest relevant to this article was reported.

‰€Œ|Šw‰ο Acta Medica Okayama 0013-7626 76 1 2007 Partial Fertility Restoration as Affected by Night Temperature in a Season-dependent Male-sterile Mutant Tomato, Lycopersicon esculentum Mill 41 46 EN Masaharu Masuda Kenji Kato Kenji Murakami Hiroshi Nakamura This study was conducted to investigate the influence of night temperature on the restoration of fertility in a season-dependent male-sterile tomato mutant (T-4). Plants were grown in greenhouses, in which minimum and maximum temperatures were set at 10Ž and 28Ž by heating and ventilation, respectively. Flowers were hand-pollinated and the fruit-set, seed-set, and number of seeds were examined. The rate of fruit-set was high and did not differ much from October to February; almost all fruits formed in October had self-fertile seeds, but 80% of the fruits from November to February were parthenocarpic. The rate of fruit-set dropped from 70% in March to below 10% in May. During this period, most of the fruits were seeded, though fruit-set was low. The number of seeds per seeded fruit varied with the season, being as high as 50 seeds in October, 1-2 seeds per fruit between November and March, and 1-20 seeds per fruit between April and June. A low night temperature of 12Ž did not affect fruit-set but resulted in a better seed-set than a high night temperature of 18Ž in the greenhouse. Further, pollination of the plants in phytochambers also resulted in a better fruit- and seed-set at 12Ž than 24Ž. In all cases, the influence of low temperature was more pronounced in autumn than in spring. Fruit-set was 70% at 12Ž and 46% at 24Ž. Of these fruits, 50% at 12Ž and 10% at 24Ž were seeded. It was inferred that partial fertility restoration in T-4 can be achieved by manipulation of night temperatures. The female organ was shown to be normal, functional, and compatible with wild-type pollen. From these results, the potential of the male-sterile T-4 mutant for use in a two line hybrid-seed production system was apparent. No potential conflict of interest relevant to this article was reported.

‰ͺŽR‘εŠw”_Šw•” Acta Medica Okayama 0474-0254@ 97 1 2008 Calculation of Full and Half Sib Covariances in an Artificial Autotetraploid Population Including Aneuploids, in Astragalus Sinica L. 25 31 EN Tetsuo Morisawa Kenji Kato Full and half sib covariances were investigated in an artificial autotetraploid population with random mating in Astragalus sinicus L.. Since a set of homologous chromosomes is not necessarily involved in aneuploidy, the covariances must be averaged for two cases, that is, with and without involvement. To average the covariances, the probability that a set of homologous chromosomes was involved in aneuploidy was assumed as 3/8, where g8h and g3h represent the chromosome number of a genome and the mean number of quadrivalent chromosomes formed in a euploid, respectively. The covariances were calculated under the assumption that quadrivalent chromosomes were distributed to the poles by 2-2 and 1-3 with probabilities ƒΘ 0.8 and ƒΙ 0.2 (ƒΘ{ƒΙ1) respectively, and that trisomic and pentasomic chromosomes were distributed by 1-2 and 2-3 both with a probability of 1. It was also assumed that the inbreeding coefficient of the parents was F 0, and that 2x and 2x{ 1 pollens and all female gametes could fertilize equally. The covariance of a family was taken as an average of the covariance of each sib combination in a family. As a result, the covariance of a population could be obtained as an average of the covariance of each family in a population. The coefficients of variance components calculated under these assumptions were different from those calculated under the same condition except that 2x{ 1 pollen could not fertilize. Differences in the coefficient of additive genetic variance components were about 3.3% and 7.2% for full and half sib covariances, respectively. Coefficients of the other variance components were also different between the two cases. However, 2x{1 pollen could rarely fertilize, since their ability to fertilize in a practical population were lower than 2x pollen. Therefore, it would be valid to calculate full and half sib covariances in an artificial autotetraploid population of Astragalus sinicus L. under the condition thatonly 2x pollen could fertilize. No potential conflict of interest relevant to this article was reported.

‰ͺŽR‘εŠw”_Šw•” Acta Medica Okayama 0474-0254@ 97 1 2008 Mathematical Model for the Calculation of Full and Half Sib Covariance in an Artificial Autotetraploid Population Including Aneuploids 17 24 EN Tetsuo Morisawa Kenji Kato For the estimation of genetic variance of an artificial autotetraploid population, a mathematical model of full and half sib covariances between sibs with various chromosome numbers, which were derived from euploid or aneuploid parents, was devised for a case where the inbreeding coefficient of the parents was F0. The coefficients defined in Kempthorne's model were separated into two parts: (i) A, D, T and Q, and (ii) ƒΣ and ƒΥ. The former four parameters were defined as probabilities of factor combinations, which could be compared between various sibs, for additive, digenic, trigenic, and quadrigenic effects, and were mutually independent. The latter two parameters, which were the numbers of the identical allele and the identical allele pair combinations that two sibs inherited from a parent, were defined as linear functions of the probabilities that two sibs inherited allele or allele pair from a parent, respectively. These probabilities depend on chromosome behavior during meiosis and the chromosome number of the gametes. For the estimation, it was assumed that quadrivalent chromosomes were distributed by 2-2 and 1-3 with probabilities ƒΘ and ƒΙ (ƒΘ{ƒΙ 1), respectively. The distribution of trisomic and pentasomic chromosomes to the poles was assumed to be 1-2 and 2-3. Then, the probabilities were estimated for the simple case where all male and female gametes could equally fertilize irrespective of their chromosome number, provided that tetrasomic chromosomes completely formed a quadrivalent chromosome. @The constitution of variance components were different according to the sib combinations and family. Therefore, for the calculation of the covariance of a family, the covariances between various sibs were averaged by the combination frequency in a family, and for the calculation of the covariance of population, the family's covariances were averaged by the family's frequency in the population. No potential conflict of interest relevant to this article was reported.

‰ͺŽR‘εŠw”_Šw•” Acta Medica Okayama 0474-0254 85 1 1996 ƒgƒEƒKƒ‰ƒV–{—t‚©‚η‚Μ•s’θ‰θŒ`¬‚Ι‹y‚Ϊ‚·”|—{πŒ‚Μ‰e‹Ώ 39 44 EN Kenji Kato Mitsuo Matsumoto Yuko Shimoda Shigehisa Yamasaki Fumio Shimamura Effect of culture conditions on in vitro induction of adventitious buds from leaf explant was studied in pepper cv. 'Shosuke' (Capsicum annuum L.), to establish mass propagation method of genic male sterile line, 'ms-Shosuke', which is in practice used for hybrid seed production. Left explant was trimmed from aseptically grown seedling, and a proximal quarter part of the leaf along with a small portion of petiole was placed on MS agar medium with the proximal cut end embedded in the medium. The cultures were kept at 27Ž, and illuminated for 16 hours per day (3000 lux). Leaf explants trimmed from 30 days old seedlings were inoculated on MS media supplemented with different concentrations of zeatin and casein hydrolysate (Table 1), and of BAP and IBA (Table 2). Adventitious buds were induced at high frequency on all of the culture media. Among them the following media were recommended: one to be supplemented with 3mg/I zeatin and 100mg/I casein hydrolysate, and the other with 3~5mg/I BAP and 0.2mg/I IBA. Physiological age of leaf explant, which was expressed as seedling age, proved to be a crucial factor to determine differentiation ability. Average number of adventitious buds induced from an explant was more than 12, when the explant was trimmed from 25 days old seedling (Table 3). IT was therefore concluded that just unfolded young leaf should be used as explant. To promote the development of shoots from adventitious buds, the cultures were transferred to MS medium supplemented with 1mg/I zeatin. Then well developed shoots were dipped in 1mg/I IAA solution for three days and aseptically grown on vermiculite, resulting in the establishment of plantlets with roots. Although rooting occurred in all shoots, the efficiency of shoot development from adventitious buds was only 21% in the best case (Table 4). Therefore the culture method must be further improved to increase efficiency. No potential conflict of interest relevant to this article was reported.