Papers - AKASHI Ryo
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Lotus japonicus Genetic, Mutant, and Germplasm Resources Reviewed
Hashiguchi M., Tanaka H., Muguerza M., Akashi R., Sandal N., Andersen S., Sato S.
Current protocols in plant biology 3 ( 2 ) 2018.6
Language:English Publishing type:Research paper (scientific journal) Publisher:Current protocols in plant biology
Copyright © 2018 John Wiley & Sons, Inc. A quarter of a century has passed since Lotus japonicus was proposed as a model legume because of its suitability for molecular genetic studies. Since then, a comprehensive set of genetic resources and tools has been developed, including recombinant inbred lines, a collection of wild accessions, published mutant lines, a large collection of mutant lines tagged with LORE1 insertions, cDNA clones with expressed sequence tag (EST) information, genomic clones with end-sequence information, and a reference genome sequence. Resource centers in Japan and Denmark ensure easy access to data and materials, and the resources have greatly facilitated L. japonicus research, thereby contributing to the molecular understanding of characteristic legume features such as endosymbiosis. Here, we provide detailed instructions for L. japonicus cultivation and describe how to order materials and access data using the resource center websites. The comprehensive overview presented here will make L. japonicus more easily accessible as a model system, especially for research groups new to L. japonicus research. © 2018 by John Wiley & Sons, Inc.
DOI: 10.1002/cppb.20070
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Ishigaki G., Nitthaisong P., Prasojo Y., Kobayashi I., Fukuyama K., Rahman M., Akashi R.
Asian-Australasian Journal of Animal Sciences 31 ( 5 ) 748 - 754 2018.5
Language:English Publishing type:Research paper (scientific journal) Publisher:Asian-Australasian Journal of Animal Sciences
Copyright © 2018 by Asian-Australasian Journal of Animal Sciences. Objective: The preference evaluation of cattle is an important factor for estimation and improvement of the grazing amounts of newly introduced or bred grasses or cultivars in barn. This study was performed to assess the grazing behavior (the amount of grazing and/or the grazing speed) of cattle as indirect method using newly bred Brachiaria ruziziensis tetraploid strain ‘OKI1’(BR) hay as treatment group and Cloris gayana ‘Callide’ (CG) hay as control group. It also compared the feasibility of using behavioral differences between two groups as one criteria for evaluating preference by Japanese black cattle in barn. Methods: Three experiments were carried out using 12 growing Japanese Black cattle including 6 males and 6 females. In each experiment, the four Japanese Black cattle (2 males and 2 females) were placed in separated stall and allowed to graze BR and CG in manger that was separated into two portions for about 30 min. The position and behavior of the cattle were recorded, and weighed the residual of each gay at 15 and 30 minutes after experiment start. Results: The BR was superior to CG in chemical composition such as protein, fibers and nonfibrous carbohydrate. The cattle, over all, tended to prefer BR over CG in the first half 15 minutes in terms of the time spent and amount of grazing. Additionally, growing cattle exhibited neophilia for BR bred newly. Conclusion: These findings indicated the current approach could be applied for one of criteria to evaluate the preference of hay by Japanese black cattle under indoor housing environment.
DOI: 10.5713/ajas.17.0543
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Wee C., Hashiguchi M., Ishigaki G., Muguerza M., Oba C., Abe J., Harada K., Akashi R.
Plant Genetic Resources: Characterisation and Utilisation 16 ( 2 ) 94 - 102 2018.4
Language:English Publishing type:Research paper (scientific journal) Publisher:Plant Genetic Resources: Characterisation and Utilisation
© NIAB 2017. Seed composition, including the protein, lipid and sucrose contents of 334 accessions of wild soybean(Glycine soja) collected in Japan, was evaluated using near-infrared reflectance spectroscopy(NIRS) technology. The distribution of protein, lipid and sucrose contents and correlations amongthese three classes of seed components were determined. Protein, lipid and sucrose levels ranged inaccessions from 48.6 to 57.0, 9.0 to 14.3 and 1.24 to 3.53%, respectively. Ave rage levels of protein,lipid and sucrose in the accessions were 54, 11 and 2.5%, respectively. High negative correlationswere observed between the protein and lipid contents, and the protein and sucrose contents. Meanlevels of the three constituents were compared among collection sites classified by climatic conditions.The total protein content of accessions from regions with a high annual mean temperature washigh. The protein content of accessions from the II-1 region was higher than those from the III-3region, and the sucrose content from the II-1 region was lower than those from regions III-2 andIV-3. The lipid content of plants from the II-1 region was lower than those from other regions,and the accessions in region II had a higher protein content and lower sucrose and lipid contentsthan the other regions. These results provide diverse and wide-ranged protein, lipid and sucrosecontents information of Japanese wild soybean resources according to climatic region; thus, providinga foundation for the future development and selection of new soybean varieties with desiredtraits in global environmental changes.
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Compaction Resistance of some species in Tropical grasses Reviewed
ISHIGAKI Genki, NITTHAISONG Pattama, AKASHI Ryo, FUKUYAMA Kiichi
Nihon Danchi Chikusan Gakkaihou 61 ( 1 ) 27 - 32 2018
Language:English Publishing type:Research paper (scientific journal) Publisher:Warm Regional Society of Animal Science, Japan
Heavy field equipment contributes to plant compaction and soil compaction. These phenomena impede many physiological deteriorations in tiller generation, leaf elongation and root activities and cause stunting and yield loss in grasses. We conducted a comparative study between two <i>Brachiaria</i> grasses (<i>B. ruziziensis</i> and <i>B. brizantha</i>) and rhodes grass (<i>Chloris gayana</i>). Compact pressure was conducted by one side wheel of agricultural machinery (gross weight: 2.7 t) for three times. The tolerance capacity of the three tropical grasses was investigated in terms of plant length, stem diameter, leaf emergence speed, the transition of the number of tillers and dry matter yield. For plant length and stem diameter, a significant difference (<i>P</i> < 0.05) was recognized between compaction treatment and non-compaction treatment in rhodes grass. The leaf emergence speed was decreased under compaction treatment in palisade grass significantly (<i>P</i> < 0.05). For the number of tiller regenerated, rhodes grass showed the highest value among grasses. On the other hand, ruzi grass and palisade grass exhibited the vigorous generation of new tillers after first cutting regardless of compaction treatment. The amount of second dry matter yield of three grasses were ordered as follows: palisade grass > ruzi grass > rhodes grass although the differences were not significant. In conclusion, these tropical grasses varied the responses against the compact pressure because of the differences of plant part influenced and the degree, and the different approach for the maintenance the number of tillers. Additionally, ruzi grass and palisade grass were more superior than rhodes grass, indicating that these new introduced forage grasses can be useful as an annual forage production under agricultural machinery system.
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Kunwanlee P., Tanaka H., Hashiguchi M., Gondo T., Muguerza M., Inoue T., Akashi R.
Crop Science 57 ( 6 ) 3310 - 3318 2017.11
Language:English Publishing type:Research paper (scientific journal) Publisher:Crop Science
© Crop Science Society of America. Zoysia matrella (L.) Merr. is a homoploid turfgrass that possesses intermediate traits between Z. japonica Steudel and Z. pacifica (Goudswaard) M. Hotta and Kuroki [syn. Z. matrella (L.) Merr. var. pacifica Goudswaard]. Consequently, it contributes to the growing range of variation that exists within this species. Self-pollination reduces genetic load and can express genetic variance, enabling easy identification and selection for desired traits. The aim of this study was to evaluate the effects of self-pollination of Z. matrella ‘Wakaba’ on morphological traits, genetic structure, and the possible selection of lines with superior traits in S1 progeny. Nine morphological characteristics (plant height, leaf width and length, stolon diameter and internode length, inflorescence number, ground covering, normalized difference vegetation index, and leaf color) were evaluated in the 364 S1 progeny. We have obtained S1 progeny exhibiting wide variation in morphological characteristics and moderate inbreeding depression in almost all traits after self-pollination. To infer genetic structure, a total of 26 simple sequence repeat markers were used, and Bayesian-based structure analysis grouped the progeny into three clusters. Genetic markers revealed that the level of homozygosity increased in S1 progeny caused by inbreeding. Superior progeny that exhibited high ground covering, late winter dormancy, and stay green throughout the entire winter season were selected. Self-pollination can be used for the selection of desirable traits from highly heterozygous species such as Z. matrella. Moreover, we expect that these superior progeny could be used in further study on quantitative trait loci analysis.
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Hashiguchi M., Puspasari R., Suematsu Y., Muguerza M., Tanaka H., Suzuki A., Hoffmann F., Akashi R.
Crop Science 57 ( 5 ) 2387 - 2394 2017.7
Language:English Publishing type:Research paper (scientific journal) Publisher:Crop Science
© Crop Science Society of America. Super-roots (SR), a unique in vitro cloning system of fast and continuously growing roots, has been isolated from self-incompatible Lotus corniculatus L. The objective of this research was to develop self-fertile SR plants by hybridizing SR forms of tetraploid L. corniculatus (2n = 4x = 24) with cholchicine-doubled forms of the diploid, self-fertile L. japonicus (Regel) K. Larsen (2n = 2x = 12) species. Tetraploid forms of L. japonicus ‘Miyakojima’ MG-20 (MG-20) were induced by treating seeds with 0, 0.05, 0.1, and 0.2% (w/v) colchicine solutions for 12 or 24 h. The rate of tetraploidization as determined by flow cytometry was most efficient at the lowest colchicine concentration for both treatment durations. Induced tetraploids of MG-20 had thicker stems with larger flowers and leaves compared with diploid forms of MG-20. Seeds produced by tetraploid MG-20 were also larger than those of the diploids; however, pod lengths and grain numbers were reduced. Two putative F 1 –interspecific hybrid plants were recovered, using embryo rescue, from hand-pollinated crosses between tetraploid forms of MG-20 and SR. The F 1 –interspecific hybrids displayed morphological features that were intermediate between the parental species. The root-growth rate of hybrid-derived root cultures was slightly reduced compared with the original SR. The hybrid plants are self-compatible and able to produce seeds. The interspecific hybrids obtained in this study demonstrate the potential to combine self-fertility and SR traits in Lotus forage breeding programs.
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Asanuma Y., Gondo T., Ishigaki G., Inoue K., Zaita N., Muguerza M., Akashi R.
GM Crops and Food 8 ( 2 ) 106 - 116 2017.4
Language:English Publishing type:Research paper (scientific journal) Publisher:GM Crops and Food
© 2017 Taylor & Francis. Japan imports cottonseed mainly from Australia and the USA where more than 96% of all cotton varieties grown are genetically modified (GM). GM crops undergo an environmental risk assessment (ERA) under the Law Concerning the Conservation and Sustainable Use of Biological Diversity before import into Japan. Potential adverse effects on biodiversity are comprehensively assessed based on competitiveness, production of harmful substances and outcrossing ability. Even though imported cottonseed is intended for food and feed uses and not for cultivation, the potential risks from seed spillage during transport must be evaluated. In most cases, the ERA requires data collected from in-country field trials to demonstrate how the GM crop behaves in Japan's environment. Confined field trials in Japan were conducted for the ERA of Lepidoptera-resistant and glufosinate-tolerant GM cotton (Gossypium hirsutum L.) lines GHB119 and T304-40. These lines were compared with conventional varieties for growth habit, morphological characteristics, seed dormancy, and allelopathic activity associated with competitiveness and production of harmful substances. Outcrossing ability was not a concern due to the absence of sexually compatible wild relatives in Japan. Although slight statistical differences were observed between the GM line and its conventional comparator for some morphological characteristics, transgenes or transformation were not considered to be responsible for these differences. The trial demonstrated that competitiveness and production of harmful substances by these GM cotton lines were equivalent to conventional cotton varieties that have a long history of safe use, and no potential adverse effects to biosafety in Japan were observed.
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Nitthaisong P., Ishigaki G., Fukuyama K., Akashi R.
Grassland Science 63 ( 2 ) 79 - 84 2017.4
Language:English Publishing type:Research paper (scientific journal) Publisher:Grassland Science
© 2017 Japanese Society of Grassland Science Tropical grasses with high forage quality and biomass could be grown as annuals in warm subtropical regions as an additional source of feedstock. For sustainable forage production, it is also vital to know the interactions between plant and weed for the selection of promising alternating forage grass. Brachiaria grass has been used as source of high quality forage in the tropics, and this could be developed as a promising forage grass species in this region. Therefore, this study compared the agronomic traits, productivity, and dominance to weeds in six Brachiaria cultivars with two rhodesgrass cultivars in southwestern Kyushu, Japan. This study was evaluated twice from spring to autumn in 2012. Most Brachiaria cultivars grew more vigorously than the two rhodesgrass cultivars during early seedling development in 2012. Except for ‘Llanero’, all Brachiaria cultivars had a higher dry matter yield than the two rhodesgrass cultivars. Notably, ‘Kennedy’ had the highest dry matter yield of 9.5 t ha −1 at the second cutting, resulting from substantial regrowth after the first cutting. However, two Brachiaria cultivars and one rhodesgrass cultivar evaluated in 2014 were not significantly different. Except ‘Llanero’, biomass percentage in all Brachiaria cultivars ranged from 57 to 81% at the first cutting. Subsequently, the value for the second cutting increased more than 90%. There was a significant positive correlation (P < 0.01) between dominance to weeds and growth in the early stage, indicating that the vigorous growth of Brachiaria grasses, during the early stage was superior to that of weeds in their competition. In addition, Brachiaria ruziziensis and Brachiaria decumbens could be introduced as new variety in temperate low warm region, Japan.
DOI: 10.1111/grs.12151
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Rahman M., Rahman R., Niimi M., Khadijah W., Akashi R., Abdullah R.
Sains Malaysiana 46 ( 4 ) 515 - 520 2017.4
Language:English Publishing type:Research paper (scientific journal) Publisher:Sains Malaysiana
An experiment was carried out to investigate the effects of oxalic acid administration on feed intake and nutrient digestibility in goats. Four female cross bred (Boer × local) goats (average body weight of 46.3 kg) were randomly assigned to four experimental diets including oxalic acid administration at levels of 0, 2.25, 4.50 and 6.75 g/animal/d in a 4×4 Latin Square design. Oxalic acid diluted with water was administered orally via syringe to experimental goats once daily for four experimental periods. Each experimental period was lasted 21 d in length, comprising 14 d of adaptation to the experimental diet followed by 7 d of data collection. All the animals were individually fed with Napier grass ad libitum supplemented with 300 g (fresh basis) pelleted compound feed per goat per day throughout the study. Feed composition, feed intake, nutrient intake and nutrient digestibility were determined. Intakes of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fibre (NDF) and metabolisable energy tended to linearly decrease with the increasing rate of oxalic acid administration, with the value in the 6.75 g oxalic acid/animal/d treatment being significantly (p < 0.05) lower than the control (0 g oxalic acid/animal/d) treatment. The oxalic acid administration had no effect on apparent digestibilities of DM, OM, CP and NDF. The experiment demonstrated that oxalic acid administration may influence in the DM and nutrient intakes, but not influence on DM and nutrient digestibilities in goats.
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Fatty acid composition and distribution in wild soybean (Glycine soja) seeds collected in Japan Reviewed
Wee C., Hashiguchi M., Anai T., Suzuki A., Akashi R.
Asian Journal of Plant Sciences 16 ( 2 ) 52 - 64 2017.3
Language:English Publishing type:Research paper (scientific journal) Publisher:Asian Journal of Plant Sciences
© 2017 Chi-Do Wee et al. Background: Understanding the distribution of fatty acids in wild soybean accession collected in Japan and the relationship of geographic and environmental factors in the accumulation of fatty acids is fundamental for using the wild accessions as resources for the future development and selection of new soybean varieties with desired traits. Materials and Methods: The fatty acid composition of seeds from 319 wild soybean (Glycine soja) accessions collected in Japan were evaluated using gas chromatography. Results: The distributions of palmitate (16:0), stearate (18:0), oleate (18:1), linoleate (18:2) and α-linolenate (18:3) in seeds were determined for each accession. Significant inverse correlations were observed between the oleate and α-linolenate contents and the linoleate and α-linolenate contents. Moreover, a weak inverse correlation between the stearate and α-linolenate contents was indicated and an inverse correlation between the palmitate and linoleate contents was also found. The total palmitate content and total stearate content of Glycine soja collected from regions with high annual temperatures were high and the total α-linolenate content of Glycine soja collected from regions with a low annual temperature was high. Conclusion: These results provide diverse and wide-ranged fatty acid information of Japanese wild soybean resources according to climatic region for improving of new soybean varieties in global environmental changes.
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Gondo T., Umami N., Muguerza M., Akashi R.
Plant Biotechnology 34 ( 3 ) 143 - 150 2017
Language:English Publishing type:Research paper (scientific journal) Publisher:Plant Biotechnology
© 2017 The Japanese Society for Plant Cell and Molecular Biology. Napier grass (Pennisetum purpureum Schumach.) is a highly productive C4 tropical forage grass that has been targeted as a potential bioenergy crop. To further increase the efficiency of bioethanol production by molecular breeding, a reliable protocol for genetically transforming napier grass is essential. In this study, we report the creation of transgenic napier grass plants derived from embryogenic callus cultures of shoot apices. Embryogenic callus was initiated in three accessions of napier grass and a napier grass×pearl millet hybrid using Murashige and Skoog (MS) medium supplemented with 2.0 mg L-1 2,4-dichlorophenoxyacetic acid (2,4-D), 0.5 mg L-1 6-benzylaminopurine (BAP) and 50 µM copper sulfate (CuSO4). Of the accessions tested, a dwarf type with late-heading (DL line) had the best response for embryogenic callus formation. Highly regenerative calli that formed dense polyembryogenic clusters were selected as target tissues for transformation. A plasmid vector, pAHC25, containing an herbicide-resistance gene (bar) and the β-glucuronidase (GUS) reporter gene was used in particle bombardment experiments. Target tissues treated with 0.6 M osmoticum were bombarded, and transgenic plants were selected under 5.0 mg L-1 bialaphos selection. Although a total of 1400 target tissues yielded nine GUS-positive bialaphos-resistant calli, only one transgenic line that was derived from target tissue with the shortest culture term produced four transgenic plants. Thus, the length of time that the target tissue is in callus culture was one of the most important factors for acquiring transgenic plants in napier grass. This is the first report of successfully producing transgenic napier grass plants.
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Nakamura K., Kondo K., Akiyama H., Ishigaki T., Noguchi A., Katsumata H., Takasaki K., Futo S., Sakata K., Fukuda N., Mano J., Kitta K., Tanaka H., Akashi R., Nishimaki-Mogami T.
Food Chemistry 205 272 - 279 2016.8
Language:English Publishing type:Research paper (scientific journal) Publisher:Food Chemistry
© 2016 Elsevier Ltd. All rights reserved. Identification of transgenic sequences in an unknown genetically modified (GM) papaya (Carica papaya L.) by whole genome sequence analysis was demonstrated. Whole genome sequence data were generated for a GM-positive fresh papaya fruit commodity detected in monitoring using real-time polymerase chain reaction (PCR). The sequences obtained were mapped against an open database for papaya genome sequence. Transgenic construct- and event-specific sequences were identified as a GM papaya developed to resist infection from a Papaya ringspot virus. Based on the transgenic sequences, a specific real-time PCR detection method for GM papaya applicable to various food commodities was developed. Whole genome sequence analysis enabled identifying unknown transgenic construct- and event-specific sequences in GM papaya and development of a reliable method for detecting them in papaya food commodities.
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Nakamura K., Kondo K., Akiyama H., Ishigaki T., Noguchi A., Katsumata H., Takasaki K., Futo S., Sakata K., Fukuda N., Mano J., Kitta K., Tanaka H., Akashi R., Nishimaki-Mogami T.
Data in Brief 7 1165 - 1170 2016.6
Language:English Publishing type:Research paper (scientific journal) Publisher:Data in Brief
© 2016 The Authors. This article is referred to research article entitled "Whole genome sequence analysis of unidentified genetically modified papaya for development of a specific detection method" (Nakamura et al., 2016) [1].Real-time polymerase chain reaction (PCR) detection method for unauthorized genetically modified (GM) papaya (Carica papaya L.) line PRSV-YK (PRSV-YK detection method) was developed using whole genome sequence data (DDBJ Sequenced Read Archive under accession No. PRJDB3976). Interlaboratory validation datasets for PRSV-YK detection method were provided. Data indicating homogeneity of samples prepared for interlaboratory validation were included. Specificity and sensitivity test data for PRSV-YK detection method were also provided.
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The complete chloroplast genome sequence of zoysia matrella (L.) Merr. Reviewed
Tanaka H., Hirakawa H., Muguerza M., Hashiguchi M., Tabata S., Akashi R., Sato S.
Crop Science 56 ( 3 ) 1206 - 1212 2016.5
Language:English Publishing type:Research paper (scientific journal) Publisher:Crop Science
© Crop Science Society of America. Zoysia Willd. include one of the best-known turfgrasses worldwide owing to its adaptability in a wide range of environments and its tolerance to abiotic stresses including soil salinity, soil acidity, cold, drought, and heat. Here, we report the complete chloroplast genome sequence of Zoysia matrella (L.) Merr. obtained by a combination of 454 pyrosequencing and Sanger sequencing platforms. The entire chloroplast genome of Zoysia maps as a circular molecule of 135,810 bp built with a quadripartite organization: two inverted repeats (IRs) of 20,960 bp separated by a large single copy (LSC) sequence of 81,306 bp and a small single copy (SSC) sequence of 12,584 bp. The genome contains 131 unique genes, of which 20 are duplicated in the IRs. We identified a total of 42 simple sequence repeat (SSR) markers with ≥10 repeated nucleotides. Phylogenetic analysis revealed a close relationship between Zoysia and Neyraudia. This study identified genes, insertion-deletion (InDel), and SSR markers that may be useful in inferring evolutionary relationships at both the intra-and interspecific levels. Moreover, the Zoysia chloroplast genome sequence will be helpful in understanding phylogenetic and evolutionary relationships with other species in the Poaceae family and the Chloridoideae subfamily and will be valuable for biogenetic engineering, plant breeding, and ecological conservation.
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Sequencing and comparative analyses of the genomes of zoysiagrasses Reviewed
Tanaka H., Hirakawa H., Kosugi S., Nakayama S., Ono A., Watanabe A., Hashiguchi M., Gondo T., Ishigaki G., Muguerza M., Shimizu K., Sawamura N., Inoue T., Shigeki Y., Ohno N., Tabata S., Akashi R., Sato S.
DNA Research 23 ( 2 ) 171 - 180 2016.4
Language:English Publishing type:Research paper (scientific journal) Publisher:DNA Research
© The Author 2016. Published by Oxford University Press on behalf of Kazusa DNA Research Institute. Zoysia is a warm-season turfgrass, which comprises 11 allotetraploid species (2n = 4x = 40), each possessing different morphological and physiological traits. To characterize the genetic systems of Zoysia plants and to analyse their structural and functional differences in individual species and accessions, we sequenced the genomes of Zoysia species using HiSeq and MiSeq platforms. As a reference sequence of Zoysia species, we generated a high-quality draft sequence of the genome of Z. japonica accession 'Nagirizaki' (334 Mb) in which 59,271 protein-coding genes were predicted. In parallel, draft genome sequences of Z. matrella 'Wakaba' and Z. pacifica 'Zanpa' were also generated for comparative analyses. To investigate the genetic diversity among the Zoysia species, genome sequence reads of three additional accessions, Z. japonica 'Kyoto', Z. japonica 'Miyagi' and Z. matrella 'Chiba Fair Green', were accumulated, and aligned against the reference genome of 'Nagirizaki' along with those from 'Wakaba' and 'Zanpa'. As a result, we detected 7,424,163 single-nucleotide polymorphisms and 852,488 short indels among these species. The information obtained in this study will be valuable for basic studies on zoysiagrass evolution and genetics as well as for the breeding of zoysiagrasses, and is made available in the 'Zoysia Genome Database' at http://zoysia.kazusa.or.jp.
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Genetic structure and speciation of zoysiagrass ecotypes collected in Japan Reviewed
Tanaka H., Tokunaga R., Muguerza M., Kitazaki Y., Hashiguchi M., Sato S., Tabata S., Akashi R.
Crop Science 56 ( 2 ) 818 - 826 2016.3
Language:English Publishing type:Research paper (scientific journal) Publisher:Crop Science
© Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved. Zoysia japonica Steudel, Z. matrella (L.) Merrill, and Z. pacifica (Goudswaard) M. Hotta and Kuroki [syn. Z. matrella (L.) Merr. var. pacifica Goudswaard] are native turfgrass species in Japan and are the most economically important species of this genus. Interspecific crossing within Zoysia is possible because of the similarity in chromosome number (2n = 4x = 40), and ecotypes with intermediate traits are found along species borders. The objectives of this study were to characterize morphological traits and determine genetic variation and population structure among 248 Zoysia accessions that we have collected throughout Japan since 1996. The accessions were classified into three species, Z. japonica, Z. matrella, and Z. pacifica. By using microsatellite markers and principal coordinate analysis (PCoA), we detected high genetic diversity among the accessions. Moreover, both PCoA and Bayesian-based Structure analysis revealed two distinct populations represented by Z. japonica and Z. pacifica, while both ancestries were found in Z. matrella. On the basis of these results, we suggest that Z. matrella might represent an interspecific hybrid between Z. japonica and Z. pacifica; however, further research is required to confirm this hypothesis. Differentiation among subpopulations (R ST ) showed a mean value of 0.067 and a mean fixation index of individuals relative to the subpopulations (R IS ) of -0.060. This indicated moderate genetic differentiation and an excess of heterozygotes among the accessions, and probably reflected recent adaptive radiation of the species following polyploidization and hybridization in the presence of ongoing gene flow.
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Monda K., Araki H., Kuhara S., Ishigaki G., Akashi R., Negi J., Kojima M., Sakakibara H., Takahashi S., Hashimoto-Sugimoto M., Goto N., Iba K.
Plant Physiology 170 ( 3 ) 1435 - 1444 2016.3
Language:English Publishing type:Research paper (scientific journal) Publisher:Plant Physiology
© 2016 American Society of Plant Biologists. All Rights Reserved. The rate of gas exchange in plants is regulated mainly by stomatal size and density. Generally, higher densities of smaller stomata are advantageous for gas exchange; however, it is unclear what the effect of an extraordinary change in stomatal size might have on a plant’s gas-exchange capacity. We investigated the stomatal responses to CO2 concentration changes among 374 Arabidopsis (Arabidopsis thaliana) ecotypes and discovered that Mechtshausen (Me-0), a natural tetraploid ecotype, has significantly larger stomata and can achieve a high stomatal conductance. We surmised that the cause of the increased stomatal conductance is tetraploidization; however, the stomatal conductance of another tetraploid accession, tetraploid Columbia (Col), was not as high as that in Me-0. One difference between these two accessions was the size of their stomatal apertures. Analyses of abscisic acid sensitivity, ion balance, and gene expression profiles suggested that physiological or genetic factors restrict the stomatal opening in tetraploid Col but not in Me-0. Our results show that Me-0 overcomes the handicap of stomatal opening that is typical for tetraploids and achieves higher stomatal conductance compared with the closely related tetraploid Col on account of larger stomatal apertures. This study provides evidence for whether larger stomatal size in tetraploids of higher plants can improve stomatal conductance.
DOI: 10.1104/pp.15.01450
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Nitthaisong P., Ishigaki G., Tanaka H., Akashi R.
Crop Science 56 ( 1 ) 312 - 321 2016.1
Language:English Publishing type:Research paper (scientific journal) Publisher:Crop Science
© Crop Science Society of America. All rights reserved. The genus Brachiaria contains approximately 100 identified species, including economically important tropical grasses; however, there is not much accessible information about the genetics or genomes of the genus. In this study, we determined the chromosome number and genome size by cytological analysis and flow cytometry, respectively, and estimated the molecular variability using intersimple sequence repeat (ISSR) markers for 28 accessions representing 11 Brachiaria species. The chromosome number of 10 species agreed with previous reports, and the chromosome number for B. xantholeuca was evaluated (2n = 4x = 36) for the first time. Genome size expressed as C values differed among these species (0.89 to 4.02 pg/2C) and increased with increasing ploidy levels. In contrast, the genome size given as a Cx value tended to decrease with increasing ploidy levels in polyploid plants. A total of 441 ISSR fragments were generated with 10 primers to assess the molecular variability of Brachiaria species. All 11 Brachiaria species clustered into three groups with the neighbor-joining (NJ) method. We found no correlation between the clusters and the region from where the plants were collected. Nevertheless, the clustering of accessions was clearly correlated with ploidy level and reproductive mode (sexual and apomictic) except for a few accessions. Furthermore, evolution of the Brachiaria genome and genetic diversity within the genus were discussed.
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Tanaka H., Chotekajorn A., Kai S., Ishigaki G., Hashiguchi M., Akashi R.
Cytologia 81 ( 1 ) 95 - 102 2016
Language:English Publishing type:Research paper (scientific journal) Publisher:Cytologia
© 2016 The Japan Mendel Society. Lotus is a leguminous and cosmopolitan genus in the Loteae tribe consisting of more than 200 species. The number of chromosomes has been reported for many Lotus species; however, molecular studies have focused only on a few important species of this genus. The present study was conducted to estimate the genome size and ploidy levels of 28 Lotus accessions, and to identify their genetic diversity using inter-simple sequence repeat (ISSR) analysis. The chromosome number of 16 accessions agreed with previous reports (except for Lotus salsuginosus), while that in 11 accessions were reported here for the first time. The smallest nuclear DNA content was identified in the diploid, Lotus unifoliolatus (0.28±0.01 pg C -1 ). In contrast, the tetraploid, Lotus australis, had a genome size of 1.28±0.03 pg C -1 , representing a five-fold difference in genome size among the Lotus species. When expressed as a per Cx value, Lotus species genome sizes ranged from 0.28 pg Cx -1 in L. unifoliolatus to 0.71 pg Cx -1 in Lotus wrightii, representing a 2.5-fold difference. There was no relationship between genome size and chromosome number or ploidy level; thus, genome size is species specific in the Lotus species. On ISSR analysis, a total of 379 fragments were generated with 12 primers, and all accessions were grouped into four clusters by phylogenetic analysis. The results of this investigation will be useful for plant breeders attempting to expand the genetic variation found in this species by crossbreeding using these resources.
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Yamamoto A., Hashiguchi M., Akune R., Masumoto T., Muguerza M., Saeki Y., Akashi R.
Australian Journal of Botany 64 ( 4 ) 277 - 284 2016
Language:English Publishing type:Research paper (scientific journal) Publisher:Australian Journal of Botany
Several zoysiagrasses (Zoysia spp.) have been reported to have leaf-epidermal salt glands, and it has been suggested that salt gland density, salt secretion and salt tolerance are positively correlated. The economically most important Zoysia species are Zoysia japonica Steud., Zoysia matrella Merr., and Zoysia pacifica (Goudswaard) M. Hotta & Kuroki, and among these, Z. matrella is considered to be the most salt-tolerant. In this study, we investigated the salt gland density, and characterised the secretion and accumulation of Na+ of 48 accessions of the three Zoysia species. We did not find any morphological differences in salt glands of Z. japonica and Z. pacifica, but large bicellular salt glands were found only on the adaxial side of Z. matrella. In addition, salt gland density differed significantly within and between the species. Under salt stress, all accessions accumulated and secreted Na+ at different rates. Z. japonica was a salt-accumulating type, whereas Z. matrella and Z. pacifica secreted most of the absorbed salt. However, the correlation between salt gland density and salt accumulation/secretion were not observed. Furthermore, Z. pacifica had the lowest gland density but showed the highest Na+ uptake and a secretion rate similar to most salt-tolerant Z. matrella. These results suggest that response to salt stress, namely, salt accumulation/secretion, is different between species, and that salt gland density and salt secretion are not always positively correlated.
DOI: 10.1071/BT15261