Papers - SAEKI Yuichi
-
Effect of Drought Stress and Short-term Recovery on Proline and Polyamine Metabolism in Lotus japonicus Reviewed International coauthorship
Lee Y., Yamamoto A., Ragaey M., Hashiguchi M., Akashi R., Saeki Y.
Agricultural Research 15 105 - 118 2026.3
Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Agricultural Research
Environmental issues, particularly drought and soil salinity, severely limit plant productivity. This study aimed to examine the general reaction of legumes, specifically Lotus japonicus, against drought stress and their recovery following rehydration. After a 5-week culturing period, drought stress was simulated by withholding irrigation for 7 days. Stress response and recovery were evaluated through bioassays, and measurements of chlorophyll, proline and polyamine (stress reactants), and hydrogen peroxide and malondialdehyde (oxidative stress indices). Drought stress inhibited overall growth and decreased relative water content, but a recovery to control levels was observed after 8 h of re-watering. Hydrogen peroxide and malondialdehyde levels increased under drought stress, but showed no significant difference from control levels upon recovery. The accumulation of proline and polyamines was also observed, suggesting that they are effective responses to drought stress in plants. Furthermore, gene expression of key enzymes involved in proline and polyamine metabolism was regulated by stress conditions. By a short 8-h recovery period, the expression levels of metabolism-related genes of proline and polyamine returned to the pre-stress level, but the accumulation of functional substances was not induced. This study provides insight into the physiological and biochemical changes that occur in plants under drought stress and highlights the importance of proline and polyamine metabolism in plant adaptation to drought stress.
-
Effects of Soil Moisture Content and Rj Genotype Differences on Soybean Productivity and Soybean-nodulating Bradyrhizobial Occupancy Reviewed
Soto Ito1, Shingo Matsumoto, Masayuki Kadowaki, Hirokazu Sato, Yuichi Saeki, and Sokichi Shiro
Microbes and Environments 41 ( 1 ) 2026.3
Language：English Publishing type：Research paper (scientific journal)
-
Unexpected Occurrence of Triploids and Preliminary Assessment of Genetic Relationships Using SSR Markers in Rubus parvifolius on Amami Oshima and Kakeroma, Japan Reviewed
Saki Toshima · Kodai Egashira · Makiko Mimura · Yuichi Saeki · Tomonari Hirano · Hisato Kunitake
Plant Molecular Biology Reporter 44 56 2026.2
Language：English Publishing type：Research paper (scientific journal)
-
Differential salt stress responses and the role of polyamine metabolism in Lotus japonicus ecotypes Reviewed International coauthorship
Yongjae Lee, Akihiro Yamamoto, Chika Kuranaga-Kubo, Marwa Ragaey, Masatsugu Hashiguchi, Ryo Akashi, Yuichi Saeki
Discover Plants 2 252 2025.8
Authorship：Last author Language：English Publishing type：Research paper (scientific journal)
-
Impact of Inoculations with Indigenous Bradyrhizobium diazoefficiens Isolates on Productivity and Competition with Indigenous Bradyrhizobia in Adzuki Bean (Vigna angularis) Reviewed
Sokichi Shiro, Ryu Makihara, Shota Nakao, Masayuki Kadowaki, Yuichi Saeki
Microbes and Environments 40 ( 1 ) ME24069 2025.3
Authorship：Last author Language：English Publishing type：Research paper (scientific journal)
-
Soybean gene expression correlated with symbiotic rhizobial nitrogen fixation activity Reviewed
Yano Shunichi, Takushima Teruya, Ezawa Tatsuhiro, Sugimura Yusaku, Yamamoto Akihiro, Saeki Yuichi
Plant Root 18 35 - 47 2024.12
Authorship：Last author, Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：根研究学会
Soybean (<i>Glycine max</i> L.) can establish a symbiotic relationship with rhizobia. However, little is known about the host plant genes that correlate with the nitrogen fixation activity of symbiotic rhizobia. In this study, we investigated soybean genes that correlate with bacterial symbiotic nitrogen fixation in two experiments. In the first experiment, soybean seeds were inoculated with two strains of soybean rhizobia exhibiting different nitrogen fixation activities and were grown in the field until the R1 stage. Subsequently, the roots and nodules were subjected to RNA-seq analysis to identify the expression of soybean genes related to bacterial nitrogen fixation. In the second experiment, to confirm host gene expressions dependent on bacterial nitrogen fixation activity, nod<sup><sup>+</sup></sup>/fix<sup><sup>－</sup></sup> (Δ<i>nif</i> gene) mutants and the wild type were inoculated into soybean, and gene expressions were evaluated by qRT-PCR. <i>GmNRT2.5</i>, a high-affinity nitrate transporter gene, was correlated with nitrogen fixation activity. qPCR analysis of roots and nodules inoculated with a nod<sup><sup>+</sup></sup>/fix<sup><sup>－</sup></sup> mutant revealed that <i>GmNRT2.5</i> on chromosome 8 (Glyma.08G284000: <i>GmNRT2.5</i> Chr8) was particularly correlated with nitrogen fixation activity in the root nodule section. Based on the results, it is suggested that <i>GmNRT2.5</i> Chr8 may function as a regulatory gene bridging nitrogen fixation and nitrate absorption from the soil. Therefore, <i>GmNRT2.5</i> Chr8 might be a useful host gene for estimating symbiotic nitrogen fixation activity.
-
Effect of harvest time of day on the isoflavone synthesis pathway in immature soybeans Reviewed International coauthorship
Ismayawati, A.D., Yokoyama, D., Nishiguchi, Y., Saeki, Y., Sakakibara, H.
Food Research 8 ( 6 ) 411 - 417 2024.12
Language：English Publishing type：Research paper (scientific journal)
-
Effects of NaCl Treatment on Root Nodule Formation, Isoflavone Secretion in Soybean, and Nodulation Gene Expression in Rhizobia Reviewed International journal
Yoshikazu Nitawaki, Takaaki Yasukochi, Shinya Naono, Akihiro Yamamoto, and Yuichi Saeki
Microbes and Environments 39 ( 4 ) 2024.12
Authorship：Last author, Corresponding author Language：English Publishing type：Research paper (scientific journal)
We herein investigated the effects of salt (NaCl) stress on soybean nodulation by rhizobial strains. We specifically examined: (1) the effects of NaCl on nodule maturity and positioning by inoculating three rhizobial strains (Bradyrhizobium diazoefficiens USDA110T, Bradyrhizobium elkanii USDA31, and Sinorhizobium fredii USDA191) onto soybean variety CNS, (2) the effects of the NaCl treatment on isoflavones (daidzein and genistein) secretion by CNS, (3) the effects of the NaCl treatment on gene expression induced by daidzein and genistein in rhizobia, and (4) the effects of the NaCl treatment on rhizobial growth. The results obtained were as follows: (1) the NaCl treatment delayed nodule development and reduced nodulation on the primary root following the USDA110T inoculation, minimal sensitivity regarding nodule formation in the USDA 31 inoculation, and significantly increased the mature nodule number and nodules on the primary root following the USDA 191 inoculation. (2) The NaCl treatment significantly reduced the secretion of daidzein from soybean roots, but did not significantly affect that of genistein. (3) NaCl treatment induced a significant decrease in genistein-induced nodC expression in USDA110T, but not in USDA31, and also caused a significant reduction in daidzein-induced nodC expression, but not genistein-induced expression, in USDA191. (4) NaCl treatment reduced survivability under acidic conditions, but increased survivability under saline-alkaline conditions for USDA191 than bradyrhizobia. These results indicate that saline conditions give S. fredii a competitive advantage over Bradyrhizobium during soybean infection.
-
Compatibility of adzuki bean (Vigna angularis) and Bradyrhizobium USDA strains, and geographical distribution and community structure on indigenous adzuki bean-nodulating bradyrhizobia in Japan Reviewed
Sokichi Shiro, Ryu Makihara, Masahiro Yamaguchi, Masayuki Kadowaki, Yuichi Saeki
Plant Protection Science 59 ( 3 ) 217 - 232 2023.9
Authorship：Last author Language：English Publishing type：Research paper (scientific journal)
DOI： 10.17221/64/2022-PPS
-
Land utilization types impacted the species diversity and population distribution of nodulating and non-nodulating rhizobia in the Philippines Reviewed International coauthorship
Maria Luisa T. Mason, Baby Lyn T. De Guzman, Ariel G. Mactal, Akihiro Yamamoto , Yuichi Saeki
Rhizosphere 27 2023.7
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)
-
Development of an effective method of human DNA extraction from soil as forensic evidence Reviewed International coauthorship
Hiroko Hirashima, Rinnosuke Hisazumi, Maria Luisa T. Mason, Akihiro Yamamoto, Yuichi Saeki
Forensic Science International 335 2022.3
Authorship：Last author, Corresponding author Language：English Publishing type：Research paper (scientific journal)
-
栽培温度がダイズの生育および感染ダイズ根粒菌の群集構造に及ぼす影響 Reviewed
城 惣吉，間塚真矢，門脇正行，佐伯雄一
日本土壌肥料学雑誌 92 ( 3 ) 255 - 262 2021.6
Authorship：Last author Language：Japanese Publishing type：Research paper (scientific journal)
地球温暖化に伴う気候変動の作物生産への影響に関する基礎的知見の蓄積の一環として，異なる栽培温度環境 下におけるダイズの生育と有用ダイズ根粒菌の接種効果および感染ダイズ根粒菌群集構造への影響について調査 を行った.供試ダイズ品種として，‘オリヒメ’，‘ボンミノリ’，‘フクユタカ’ を用い，供試菌株として Bradyrhizo- bium diazoefficiens USDA110T を用いた.栽培は温度傾斜型チャンバー内で行い，低温区，中温区，高温区を設 けた.異なる温度環境下での栽培試験の結果，無接種区と比較して，USDA110 の接種により主茎長，主茎節数， 茎葉乾物重，莢数，莢乾物重，地上部乾物重，根粒数が有意に増加したが，栽培温度の上昇により根粒数を除く項 目が有意に減少した.各調査項目間の相関係数は根粒数と茎葉乾物重との関係など多くの組み合わせにおいて有意 な正の相関関係を示した.USDA110 の根粒占有率は，全ての温度区で接種した USDA110 が優占したが，低温区 と中温区，低温区と高温区を比較すると栽培温度の上昇により減少する傾向を示した.以上の結果から，高温環境 下では根粒数が減少することでダイズの生育が抑制され，その後の生育や収量に影響すると考えられた.しかし， 根粒数と USDA110 の根粒占有率を確保することができれば栽培温度の上昇によるダイズの生産性低下を抑制する ことができると考えられる.
-
Effect of salt stress on soybean growth and nodulation under inoculation with soybean rhizobia Reviewed
Yoshikazu Nitawaki, Hayato Kitabayashi, Maria Luisa Tabing Mason, Akihiro Yamamoto, Yuichi Saeki
Soil Science and Plant Nutrition 67 ( 2 ) 103 - 113 2021.5
Authorship：Last author, Corresponding author Language：English Publishing type：Research paper (scientific journal)
Salinity is one of the major problems when it comes to soil fertility and agricultural productivity. In this regard, this study aimed to elucidate the influence of four salinity levels (0, 20, 50, 100 mM NaCl) on the soybean growth and the nodulation by rhizobia inoculated on the soybean variety CNS. Additionally, the compatibility of soybean varieties with the seven representative strains of rhizobia was also investigated. Through the compatibility test, it was revealed that the Sinorhizobium (Ensifer) fredii USDA 191 and the three bradyrhizobia (Bradyrhizobium japonicum USDA 6T, B. elkanii USDA 31, and B. diazoefficiens USDA 110T) showed compatible nodulation with the Rfg1 genotype soybean, whereas, the S. fredii USDA 192, 193, and 205T showed incompatible nodulation. The inoculation tests with bradyrhizobia (USDA 31, 110T) and sinorhizobia (USDA 191, 192, 193) indicated a better growth of soybean for bradyrhizobia than the sinorhizobia until 50 mM NaCl. Note that even though the symbiotic efficiency at each strain was not different among 0, 20, and 50 mM NaCl treatments, the symbiotic efficiency of bradyrhizobia was higher than the sinorhizobia at each NaCl treatment. The result of the mix inoculation test indicated that the nodule occupancy rate of strain USDA 191 increased significantly along with the NaCl concentration but strain USDA 110T showed an opposite response. These results indicate a positive relationship between the soybean growth and the nitrogen fixation ability of the inoculant under salt-stress conditions. Furthermore, the results obtained from the mix inoculation test partly describe the dominance of sinorhizobia under saline conditions.
-
Maria Luisa T. Mason, Baby Lyn T. De Guzman, Akihiro Yamamoto, Yuichi Saeki
Symbiosis 83 ( 1 ) 55 - 63 2021.1
Authorship：Last author, Corresponding author Language：English Publishing type：Research paper (scientific journal)
This report aimed to evaluate the ability of the dominant indigenous strains of bradyrhizobia obtained from different locations in the Philippines in terms of their symbiosis, N-fixation and nodulation with various soybean cultivars harboring different Rj genotypes. This was done to select the most efficient and effective strain that can be used as an inoculant under the Philippines’ local condition. Two soybean cultivars from the Philippines and three cultivars from Japan and Brazil were used and inoculated with 12 indigenous strains and the reference strain Bradyrhizobium diazoefficiens USDA110. Culture pots were grown inside a growth chamber for four weeks with 33 °C for 16 h as daytime and 28 °C for 8 h as night time. All the strains formed nodules on all soybean cultivars, except for B. elkanii BO-4, which only formed nodules on Philippines’ cultivars. Among the indigenous strains, B. elkanii IS-2 is significantly the most efficient and effective N-fixer than the other strains for the Philippines’ cultivars. In contrast, B. diazoefficiens SK-5 was found to be the most efficient and effective N-fixer for cultivars from Japan and Brazil. Additionally, a positive correlation was observed between the symbiotic efficiency and the nitrogenase activity indicating an efficient N-fixation by the indigenous strains. Thus, we were able to identify the most promising indigenous bradyrhizobia that could be used as an inoculant to increase the soybean yield in the Philippines and provided insights on soybean inoculation.
-
Latitudinal Characteristic Nodule Composition of Soybean-Nodulating Bradyrhizobia: Temperature-Dependent Proliferation in Soil or Infection? Reviewed
Md Hafizur Rahman Hafiz, Ahsanul Salehin, Fumihiko Adachi, Masayuki Omichi, Yuichi Saeki, Akihiro Yamamoto, Shohei Hayashi, Kazuhito Itoh
Horticulturae 2021.1
Language：English Publishing type：Research paper (scientific journal)
Abstract: A species-specific latitudinal distribution of soybean rhizobia has been reported; Bradyrhi- zobium japonicum and B. elkanii dominate in nodules in northern and southern areas, respectively. The aim of this study was to elucidate whether temperature-dependent proliferation in soil or infec- tion is more reliable for determining the latitudinal characteristic distribution of soybean-nodulating rhizobia under local climate conditions. Three study locations, Fukagawa (temperate continental climate), Matsue and Miyazaki (humid sub-tropical climate), were selected in Japan. Each soil sample was transported to the other study locations, and soybean cv. Orihime (non-Rj) was pot-cultivated using three soils at three study locations for two successive years. Species composition of Bradyrhi- zobium in the nodules was analyzed based on the partial 16S rRNA and 16S–23S rRNA ITS gene sequences. Two Bradyrhizobium japonicum (Bj11 and BjS10J) clusters and one B. elkanii (BeL7) cluster were phylogenetically sub-grouped into two (Bj11-1-2) and four clusters (BjS10J-1-4) based on the ITS sequence. In the Fukagawa soil, Bj11-1 dominated (80–87%) in all study locations. In the Matsue soil, the composition was similar in the Matsue and Miyazaki locations, in which BeL7 dominated (70–73%), while in the Fukagawa location, BeL7 decreased to 53% and Bj11-1 and BjS10J-3 increased. In the Miyazaki soil, BeL7 dominated at 77%, and BeL7 decreased to 13% and 33% in the Fukagawa and Matsue locations, respectively, while BjS10J-2 and BjS10J-4 increased. It was supposed that the B. japonicum strain preferably proliferated in the Fukagawa location, leading to its nodule domi- nancy, while in the Miyazaki location, temperature-dependent infection would lead to the nodule dominancy of B. elkanii, and both factors would be involved in the Matsue location.
-
品評会における煎茶の評価とアミノ酸、カテキン類、テオガリン、没食子酸およびカフェインとの関係 Reviewed
児崎章憲，山本昭洋，佐伯雄一
茶業研究報告 129 11 - 18 2020.8
Language：Japanese Publishing type：Research paper (scientific journal)
-
品評会における煎茶の評価と茶葉中無機元素含有量との関係 Reviewed
児崎章憲，山本昭洋，佐伯雄一
茶業研究報告 129 19 - 26 2020.8
Language：Japanese Publishing type：Research paper (scientific journal)
-
Okamura Y, Morimoto N, Ikeda D, Mizusawa N, Watabe S, Miyanishi H, Saeki Y, Takeyama H, Aoki T, Kinoshita M, Kono T, Sakai M, Hikima J
Frontiers in Immunology 11 425-1 - 425-17 2020.3
Language：English Publishing type：Research paper (scientific journal)
-
Metagenomic study of endophytic bacterial community of sweet potato (Ipomoea batatas) cultivated in different soil and climatic conditions Reviewed
Ramesh Raj Puri, Fumihiko Adachi, Masayuki Omichi, Yuichi Saeki, Akihiro Yamamoto, Shohei Hayashi, Md Arshad Ali, Kazuhito Itoh
World Journal of Microbiology and Biotechnology 35 ( 176 ) 1 - 8 2019.10
Language：English Publishing type：Research paper (scientific journal)
-
Culture-dependent analysis of endophytic bacterial community of sweet potato (Ipomoea batatas) in different soils and climates Reviewed
Ramesh Raj Puri, Fumihiko Adachi, Masayuki Omichi, Yuichi Saeki, Akihiro Yamamoto, Shohei Hayashi, Kazuhito Itoh
Journal of Advances in Microbiology 13 ( 2 ) 1 - 12 2018.11
Language：English Publishing type：Research paper (scientific journal)