Japanese Society of BreedingActa Medica Okayama1344-76107532025Polyphyletic domestication and inter-lineage hybridization magnified genetic diversity of cultivated melon, Cucumis melo L.168178ENKatsunoriTanakaFaculty of Agriculture and Life Science, Hirosaki UniversityGentaroShigitaGraduate School of Environmental and Life Science, Okayama UniversityTran PhuongDungGraduate School of Environmental and Life Science, Okayama UniversityPhan Thi PhuongNhiUniversity of Agriculture and Forestry, Hue UniversityMamiTakahashiGraduate School of Environmental and Life Science, Okayama UniversityYukiMondenGraduate School of Environmental, Life, Natural Science and Technology, Okayama UniversityHidetakaNishidaGraduate School of Environmental, Life, Natural Science and Technology, Okayama UniversityRyujiIshikawaFaculty of Agriculture and Life Science, Hirosaki UniversityKenjiKatoGraduate School of Environmental, Life, Natural Science and Technology, Okayama UniversityMelon 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 Okayama0305-736413572025Molecular polymorphisms of the nuclear and chloroplast genomes among African melon germplasms reveal abundant and unique genetic diversity, especially in Sudan13291343ENOdirichi NnennayaImohGraduate School of Environmental and Life Science, Okayama UniversityGentaroShigitaGraduate School of Environmental and Life Science, Okayama UniversityMitsuhiroSugiyamaInstitute of Vegetable and Floriculture Science, National Agriculture and Food Research Organization (NARO)Tran PhuongDungGraduate School of Environmental and Life Science, Okayama UniversityKatsunoriTanakaFaculty of Agriculture and Life Science, Hirosaki UniversityMamiTakahashiGraduate School of Environmental and Life Science, Okayama UniversityKazusaNishimuraGraduate School of Environmental, Life, Natural Science and Technology, Okayama UniversityYukiMondenGraduate School of Environmental, Life, Natural Science and Technology, Okayama UniversityHidetakaNishidaGraduate School of Environmental, Life, Natural Science and Technology, Okayama UniversityMashaerGodaPlant Genetic Resources Conservation and Research Center, Agricultural Research CorporationMichelPitratINRAE, UR1052, Génétique et amélioration des fruits et légumesKenjiKatoGraduate School of Environmental, Life, Natural Science and Technology, Okayama UniversityBackground 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 regionf, 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 LLCActa Medica Okayama0925-98647132023Analysis of genetic diversity and population structure in Cambodian melon landraces using molecular markers10671083ENPervin MstNazninGraduate School of Environmental and Life Science, Okayama UniversityOdirichi NnennayaImohGraduate School of Environmental and Life Science, Okayama UniversityKatsunoriTanakaFaculty of Agriculture and Life Science, Hirosaki UniversityOuchSreynechCambodian Agricultural Research and Development InstituteGentaroShigitaDepartment of Life Science Systems, Technical University of MunichYonSopheaCambodian Agricultural Research and Development InstituteSakhanSophanyCambodian Agricultural Research and Development InstituteOukMakaraPlant Breeder, Retired Director of the Cambodian Agricultural Research and Development InstituteNorihikoTomookaResearch Center of Genetic Resources, National Agriculture and Food Research Organization (NARO)YukiMondenGraduate School of Environmental and Life Science, Okayama UniversityHidetakaNishidaGraduate School of Environmental and Life Science, Okayama UniversityKenjiKatoGraduate School of Environmental and Life Science, Okayama UniversityGenetic 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 thomh 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 BreedingActa Medica Okayama1344-76107332023Elucidation of genetic variation and population structure of melon genetic resources in the NARO Genebank, and construction of the World Melon Core Collection269277ENGentaroShigitaGraduate School of Environmental and Life Science, Okayama UniversityTran PhuongDungGraduate School of Environmental and Life Science, Okayama UniversityMst. NazninPervinGraduate School of Environmental and Life Science, Okayama UniversityThanh-ThuyDuongGraduate School of Environmental and Life Science, Okayama UniversityOdirich NnennayaImohGraduate School of Environmental and Life Science, Okayama UniversityYukiMondenGraduate School of Environmental and Life Science, Okayama UniversityHidetakaNishidaGraduate School of Environmental and Life Science, Okayama UniversityKatsunoriTanakaFaculty of Agriculture and Life Science, Hirosaki UniversityMitsuhiroSugiyamaInstitute of Vegetable and Floriculture Science, National Agriculture and Food Research Organization (NARO)YoichiKawazuInstitute of Vegetable and Floriculture Science, National Agriculture and Food Research Organization (NARO)NorihikoTomookaResearch Center of Genetic Resources, National Agriculture and Food Research Organization (NARO)KenjiKatoGraduate School of Environmental and Life Science, Okayama UniversityNumerous 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 collectionh) 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.Japanese Society of BreedingActa Medica Okayama1344-76107322023Melon diversity on the Silk Road by molecular phylogenetic analysis in Kazakhstan melons219229ENKatsunoriTanakaFaculty of Agriculture and Life Science, Hirosaki UniversityMitsuhiroSugiyamaInstitute of Vegetable and Floriculture Science, National Agriculture and Food Research Organization (NARO)GentaroShigitaGraduate School of Environmental and Life Science, Okayama UniversityRyomaMurakamiFaculty of Agriculture and Life Science, Hirosaki UniversityThanh-ThuyDuongFaculty of Agronomy, University of Agriculture and Forestry, Hue UniversityYashengAierkenCenter for Hami Melon, Xinjiang Academy of Agricultural SciencesAnna MArtemyevaAll-Russian Institute of Plant Genetic Resources on the name of N.I.Vavilov (VIR)ZharasMamypbelovKazakhstan Research Institute of Potato and Vegetable Growing LLCRyujiIshikawaFaculty of Agriculture and Life Science, Hirosaki UniversityHidetakaNishidaGraduate School of Environmental and Life Science, Okayama UniversityKenjiKatoGraduate School of Environmental and Life Science, Okayama UniversityTo uncover population structure, phylogenetic relationship, and diversity in melons along the famous Silk Road, a seed size measurement and a phylogenetic analysis using five chloroplast genome markers, 17 RAPD markers and 11 SSR markers were conducted for 87 Kazakh melon accessions with reference accessions. Kazakh melon accessions had large seed with exception of two accessions of weedy melon, Group Agrestis, and consisted of three cytoplasm types, of which Ib-1/-2 and Ib-3 were dominant in Kazakhstan and nearby areas such as northwestern China, Central Asia and Russia. Molecular phylogeny showed that two unique genetic groups, STIa-2 with Ib-1/-2 cytoplasm and STIa-1 with Ib-3 cytoplasm, and one admixed group, STIAD combined with STIa and STIb, were prevalent across all Kazakh melon groups. STIAD melons that phylogenetically overlapped with STIa-1 and STIa-2 melons were frequent in the eastern Silk Road region, including Kazakhstan. Evidently, a small population contributed to melon development and variation in the eastern Silk Road. Conscious preservation of fruit traits specific to Kazakh melon groups is thought to play a role in the conservation of Kazakh melon genetic variation during melon production, where hybrid progenies were generated through open pollination.No potential conflict of interest relevant to this article was reported.ªRåw_wActa Medica Okayama2186-77551052016Molecular-based analysis of genetic diversity and classification of Japanese melon breeding lines715ENTran PhuongDungKatsunoriTanakaYukariAkashiDuong ThanhThuyHidetakaNishidaKenjiKatoFor 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 eEarlfs Favouritef 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 Favouritef or by crossing eEarlfs Favouritef with eBritish Queenf 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.ªRåw_wActa Medica Okayama0474-02549412005Cloäúâ`qÌJÔO¶çÉyÚ·øÊÌðÍ4755ENHidetakaNishidaSixteen heading-time tester lines in rice (Oryza Sativa L.) for the six loci were subjected to transfer treatments from short (10-h) to long photoperiod(24-h) and vice versa at various times. Using an analytical model, we estimated seven parameters for the three pre-flowering developmental phases of each line: the basic vegetative phase (BVP), the subsequent photoperiod-sensitive phase (PSP), and the post photoperiod-sensitive phase until heading (PPP). The Sel locus was found to have an extrremely strong effect on PSP; Ef1, a slight effect on BVP and a considerable effect on PPP; and E1, a considerable effect on PSP, although their effects were modified by nonallelic interactions at these three loci. The effects of three other loci were almost negligible. Subsequently, two late-heading mutant lines HS169 and HS276 with an extremely long basic vegetative growth (BVG; days to heading under short photoperiod) period conferred by a recessive mutant gene ef1-h and a novel gene ef2, were subjected to photoperiodic transfer treatments. Both mutant genes were found to increase BVP and PPP markedly by themselves, whereas ef1 required nonallelic interaction with the Se1 locus. Based on the results, causal genetic pathways to flowering in rice and the significance of ef1-h and ef2 in recent rice breeding in the low latitudes were discussed.No potential conflict of interest relevant to this article was reported.