研究者詳細 - 赤木　功

論文 - 赤木　功

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Akagi I., Chishaki N. . Experimental verification of solubilization effect of soil bromine by waterlogging reduction . Soil Science and Plant Nutrition71 ( 1 ) 85 - 92 2024年10月査読

記述言語：日本語出版者・発行元：Soil Science and Plant Nutrition

Although the concentration of bromine in the Earth’s crust is only approximately 2 µg g−1, it is one of the most crucial elements in daily human life. On the Earth’s surface, bromine is thought to be widely transported and circulated in the hydrosphere, atmosphere, lithosphere, and biosphere. However, little is known regarding the dynamics of bromine in the terrestrial environments. In this study, waterlogging incubation tests were conducted on two soil types, Lowland soil and Andosol, to verify the solubilization effect of waterlogging on soil bromine. The amount of bromine in the soil extracts increased considerably with incubation time in Lowland soil and Andosol, proving that the soil reduction caused by waterlogging enhanced the solubilization of soil bromine. The amount of bromine solubilized by soil reduction tended to be higher in Andosols, which had a higher total bromine concentration than Lowland soil. The amount by soil reduction during the 28 days period ranged from 0.18 to 1.14 µg g−1 for the Lowland soil group and from 0.20 to 30.2 µg g−1 for the Andosol group. Solubilized bromine could not remain in the soil, and most of it leached out with the percolation water, as shown by the soil-filled column tests. To estimate the amount of bromine leached from a rice paddy field under waterlogged conditions, a percolation test was conducted using Wagner pot-cropped paddy rice plants. The results showed that 531 to 544 mg of bromine per square meter of soil surface leached during one growing season. The amount of bromine leached from the soil was much higher than the previously reported annual amount of bromine addition to land from atmospheric deposition.

DOI： 10.1080/00380768.2024.2395857

Scopus

Libron J.A.M.A., Putri H.H., Bore E.K., Chepkoech R., Akagi I., Odama E., Goto K., Tamaru S., Yabuta S., Sakagami J.I. . Halopriming in the submergence-tolerant rice variety improved the resilience to salinity and combined salinity-submergence at the seedling stage . Plant Physiology and Biochemistry208 108494 2024年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Plant Physiology and Biochemistry

The role of halopriming in alleviating the detrimental effects of salinity and combined salinity-submergence was evaluated using two rice genotypes, “IR06F148” (anaerobic germination + submergence tolerant [Sub1]) and “Salt-star” (salt tolerant) with contrasting levels of tolerance. Nonprimed seeds and those primed with 1% calcium chloride (CaCl2) were germinated, and the seedlings were exposed to salinity (50 or 100 mM sodium chloride [NaCl]) and submergence (nonsaline or saline water). Salinity substantially inhibited plant height, shoot/root dry mass, and leaf area. Priming improved the resilience to 50 mM NaCl by increasing the chlorophyll content and lowering hydrogen peroxide (H2O2) production; and to 100 mM NaCl by increasing the total soluble sugars. However, apparent differences in the responses of primed “Salt-star”, such as an increase in the Na+, K+, and Ca2+ levels, indicated that halopriming differentially affected the response to salt based on the salinity tolerance of the variety. Submergence reduced the shoot biomass, chlorophyll, and photosynthetic efficiency to a greater extent in “Salt-star” than in “IR06F148”. Priming, especially in “Salt-star”, caused a lesser reduction in the chlorophyll (Chl) and maximum quantum yield of photosystem II (Fv/Fm) but increased the total soluble sugars post-submergence, indicating a boost in the photosynthetic efficiency. The responses of the two varieties to submergence depended on their tolerance, and halopriming affected each variety differently. The metabolic and molecular changes induced by halopriming in submergence-tolerant rice may be explored further to understand the underlying mechanisms of improved resilience.

DOI： 10.1016/j.plaphy.2024.108494

Scopus

PubMed

赤木　功・樗木直也・山本雅史・香西直子 . 鹿児島県内の生産者圃場で観察されたアボカドの葉の生理障害：塩素過剰による栄養障害の可能性 . 鹿児島大学農学部農場研究報告45 15 - 19 2024年3月査読

Nakamura M., Urakawa D., He Z., Akagi I., Hou D.X., Sakao K. . Apoptosis Induction in HepG2 and HCT116 Cells by a Novel Quercetin-Zinc (II) Complex: Enhanced Absorption of Quercetin and Zinc (II) . International Journal of Molecular Sciences24 ( 24 ) 2023年12月査読

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：International Journal of Molecular Sciences

Quercetin forms complexes with various metals due to its structural attributes. It predominantly exhibits chelating activity at the 3-hydroxy/4-carbonyl group. Previously, coordination in synthetically obtained quercetin–zinc (II) complexes has been limited to this group. However, the expanded coordination observed in quercetin–iron complexes has opened avenues for diverse applications. Thus, synthesizing novel quercetin–zinc complexes with different coordination positions is a significant advance. In our study, we not only synthesized and comprehensively characterized a new quercetin–zinc (II) complex, Zn-Q, but also evaluated the structure and bioactivity of chelate complexes (Q+Zn) derived from co-treatment in cell culture mediums. The structure of the new compound Zn-Q was comprehensively characterized using 1D 1H and 2D correlation spectroscopy (COSY), nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV-Vis), electrospray ionization mass spectrometer (ESI-MS), and X-ray diffraction analysis (XRD) analysis. Subcellular localization and absorption of these zinc (II) complexes were determined using the ZnAF-2 DA zinc ion fluorescence probe. Throughout the experiments, both Zn-Q and Q+Zn exhibited significant antioxidant, cell growth inhibitory, and anticancer effects in HepG2 and HCT116 cells, with Zn-Q showing the highest potential for inducing apoptosis via the caspase pathway. Tracking intracellular zinc complex absorption using zinc fluorescent probes revealed zinc (II) localization around the cell nucleus. Interestingly, there was a proportional increase in intracellular quercetin absorption in conjunction with zinc (II) uptake. Our research highlights the advantages of quercetin complexation with zinc (II): enhanced anticancer efficacy compared to the parent compound and improved bioavailability of both quercetin and zinc (II). Notably, our findings, which include enhanced intracellular uptake of both quercetin and zinc (II) upon complex formation and its implications in apoptosis, contribute significantly to the understanding of metal–polyphenol complexes. Moving forward, comprehensive functional assessments and insights into its mechanism of action, supported by animal studies, are anticipated.

DOI： 10.3390/ijms242417457

Scopus

PubMed

Odama E., Tsujimoto Y., Yabuta S., Akagi I., Chepkoech R., Soe I., Sakagami J.I. . Effect of P-Dipping on Growth of NERICA 4 Rice in Different Soil Types at Initial Growth Stages . Sustainability (Switzerland)15 ( 21 ) 2023年11月査読

記述言語：日本語出版者・発行元：Sustainability (Switzerland)

Phosphorus (P) deficiency resulting from P fixation is a major constraint limiting sustainable rice cultivation in sub-Saharan Africa. Soil texture also affects P availability and use efficiency. In a factorial experiment, we evaluated the combined effect of soil texture (sand, clay loam, and clay) and P treatments P-dipping (Pdip) and two other broadcasted P fertilizer levels (Brod1 and Brod2) on the growth of NERICA 4 rice in the initial growth stages. Across all soil textures and P treatments, total plant biomass ranged from 1.06 to 4.63 g pot−1. The Pdip treatment significantly increased shoot and root biomass relative to control from 1.27 to 1.98 and 0.23 to 0.38 g pot−1, respectively. Mean photosynthetic rate values under Pdip (20.1 μmol m−2 s−1), Brod2 (19.5 μmol m−2 s−1), and Brod1 (19.3 μmol m−2 s−1) treatments showed significant 42%, 37%, and 36% increases over control, regardless of soil texture. In a striking contrast, P-dipping significantly promoted growth of root length under clay soil, but without a commensurate increase in shoot P uptake. Contrary to our hypothesis, the interactive effect of soil texture and P-dipping influenced NERICA 4 shoot and root physiological and morphological characteristics under clay loam soil texture as opposed to clay.

DOI： 10.3390/su152115402

Scopus

Emmanuel Odama, Yasuhiro Tsujimoto, Shin Yabuta, Isao Akagi, Rael Chepkoech, Ibrahim Soe, Jun-Ichi Sakagami . Effect of P-dipping on above- and below-ground growth of NERICA 4 rice in different soil types . Sustainability 15 ( 21 ) 2023年10月査読

Odama E., Tsujimoto Y., Yabuta S., Akagi I., Sakagami J.I. . P-dipping improved NERICA 4 rice seedling resilience to water and nutrient stresses under rainfed-like conditions . Rhizosphere26 2023年6月査読

記述言語：日本語出版者・発行元：Rhizosphere

Drought stress and phosphorus (P) deficiency are major abiotic factors that limit the yields of rice in Sub-Saharan Africa. To improve the available P supply in the highly weathered soils in the region, farmers use several P application methods, one of which is P-dipping, i.e., dipping the root of seedlings into P-enriched slurry before transplanting. In this study, a split-plot pot experiment was conducted to determine how the effect of localized P application via P-dipping (using four P fertilizer levels) on NERICA 4 rice growth interacts with two water regimes (waterlogging and moderately dry). Shoot dry weight and plant height differed significantly under the various P-dipping application levels, with an application of 40 kg P ha−1 providing the highest mean values under both water treatments. While the mean leaf area did not statistically differ among the P-dipping treatment levels under the moderately dry condition, all P-dipping treatments had increased leaf area relative to that observed without P-dipping. Mean root length differed significantly between the water treatments, whereas the mean root dry weight was higher with the P-dipping treatments than without P-dipping under both water conditions (36% and 8% mean increases under the waterlogged and moderately dry treatments, respectively). These findings show that P-dipping improves the ability of NERICA 4 rice seedlings to withstand water and nutrient stresses under rainfed lowland at early growth stages.

DOI： 10.1016/j.rhisph.2023.100688

Scopus

Khanthavong P., Yabuta S., Malik A.I., Hossain M.A., Akagi I., Sakagami J.I. . Combinational Variation Temperature and Soil Water Response of Stomata and Biomass Production in Maize, Millet, Sorghum and Rice . Plants11 ( 8 ) 2022年4月査読

記述言語：日本語出版者・発行元：Plants

Environmental responses of stomatal conductance (gs) as basic information for a photo-synthesis-transpiration-coupled model have been increasing under global warming. This study identified the impact of gs behavior under different soil water statuses and temperatures in rice, maize, millet, and sorghum. The experiments consisted of various soil moisture statuses from flooding to drying and combination of soil moisture status and temperature. There was a reduction in shoot biomass of maize and sorghum caused by decreasing of gs, photosynthesis (A), and transpiration (E) in early imposed waterlogging without dependent temperature, whereas millet and rice were dependent on temperature variation. The effect of gradual soil drying, gs, A, and E of maize, millet, and sorghum were caused by low temperature, except rice. The impact of the combination of various soil water statuses and temperatures on gs is important for the trade-off between A and E, and consequently shoot biomass. However, we discovered that an ability to sustain gs is essential for photo assimilation and maintaining leaf temperature through evapotranspiration for biomass production, a mechanism of crop avoidance in variable soil water status and temperature.

DOI： 10.3390/plants11081039

Scopus

PubMed

Phanthasin Khanthavong, Shin Yabuta, Hidetoshi Asai, Md. Amzad Hossain, Isao Akagi, Jun-Ichi Sakagami . Root response to soil water status via interaction of crop genotype and environment . Agronomy11 ( 4 ) 1 - 15 2021年4月査読

記述言語：日本語出版者・発行元：Agronomy

Flooding and drought are major causes of reductions in crop productivity. Root distribution indicates crop adaptation to water stress. Therefore, we aimed to identify crop roots response based on root distribution under various soil conditions. The root distribution of four crops—maize, millet, sorghum, and rice—was evaluated under continuous soil waterlogging (CSW), moderate soil moisture (MSM), and gradual soil drying (GSD) conditions. Roots extended largely to the shallow soil layer in CSW and grew longer to the deeper soil layer in GSD in maize and sorghum. GSD tended to promote the root and shoot biomass across soil moisture status regardless of the crop species. The change of specific root density in rice and millet was small compared with maize and sorghum between different soil moisture statuses. Crop response in shoot and root biomass to various soil moisture status was highest in maize and lowest in rice among the tested crops as per the regression coefficient. Thus, we describe different root distributions associated with crop plasticity, which signify root spread changes, depending on soil water conditions in different crop genotypes as well as root distributions that vary depending on crop adaptation from anaerobic to aerobic conditions.

DOI： 10.3390/agronomy11040708

Scopus

赤木　功，福丸瑛里紗，樗木直也 . ネコブセンチュウの初期密度がオクラの生育および収量に及ぼす影響 . 鹿児島大学農学部農場研究報告42 1 - 6 2021年3月査読

赤木　功，樗木直也 . 鹿児島県内の農耕地土壌におけるウランの蓄積実態 . 環境化学30 133 - 139 2020年9月査読

赤木　功，原田竜海，樗木直也 . 鹿児島大学農学部附属農場で栽培されたオクラ11品種の果実中カドミウム濃度 . 鹿児島大学農学部農場研究報告 ( 39 ) 1 - 5 2018年3月

赤木　功，松平美咲，森田久美，樗木直也 . 南九州地域における施設土壌の臭素濃度 −臭化メチル全廃直前（2011年）における調査事例− . 鹿児島大学農学部学術報告67 8 - 15 2017年3月

赤木　功，冨田莉那，樗木直也 . 鹿児島市内で購入した市販園芸培養土の土壌特性とネコブセンチュウ混入の有無 . 鹿児島大学農学部附属農場報告38 1 - 5 2017年3月

赤木　功・樗木直也 . 家畜排せつ物由来メタン発酵消化液の土壌施用によるネコブセンチュウ被害軽減効果の検証 . 日本作物学会紀事86 ( 1 ) 41 - 49 2017年1月査読

赤木　功，樗木直也 . 鹿児島市における大気降下物に由来するフッ素，臭素およびヨウ素の沈着量 . 日本土壌肥料学雑誌87 ( 6 ) 430 - 437 2016年12月査読

赤木　功・樗木直也 . 施設栽培土壌における重金属濃度およびそれに対するリン酸質肥料の影響 . 環境化学25 ( 4 ) 199 - 206 2015年12月査読

樗木直也・吉田雅一・石橋裕喜・松永俊朗・赤木　功 . 農家ほ場調査より推察されるソラマメさや綿状組織黒変障害の原因 . 日本土壌肥料学雑誌86 ( 6 ) 527 - 533 2015年12月査読

Makoto Ikenaga, Masakazu Tabuchi, Takuya Oyama, Isao Akagi and Masao Sakai . Development of LNA oligonucleotide-PCR clamping technique in investigating the community structures of plant-associated bacteria . Bioscience, Biotechnology, and Biochemistry79 ( 9 ) 1556 - 1566 2015年9月査読

Isao Akagi, Yoshitaka Satoh and Naoya Chishaki . Fluorine Concentrations in Greenhouse Soils Sampled from Farms in Southern Kyushu, Japan . 環境化学25 63 - 68 2015年6月査読

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