Language：Japanese   Publisher：公益社団法人 日本アイソトープ協会  

DOI： 10.50955/happyokai.3.0_22

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1111/pce.14319

Web of Science

Scopus

PubMed

Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/pce.14319

Language：English   Publisher：Japanese Society of Breeding  

<p>Wild species in the genus <i>Vigna</i> are a great resource of tolerance to various stresses including salinity. We have previously screened the genetic resources of the genus <i>Vigna</i> and identified several accessions that have independently evolved salt tolerance. However, many aspects of such tolerance have remained unknown. Thus, we used autoradiography with radioactive sodium (²²Na⁺) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to visualize and compare Na⁺ allocation in <i>Vigna angularis</i> (Willd.) Ohwi & H.Ohashi (azuki bean), <i>Vigna nakashimae</i> (Ohwi) Ohwi & H.Ohashi, <i>Vigna riukiuensis</i> (Ohwi) Ohwi & H.Ohashi, <i>Vigna luteola</i> (Jacq.) Benth. and <i>Vigna marina</i> (Burm.) Merr.. The results indicated: 1) Tolerant accessions suppress Na⁺ accumulation compared to azuki bean. 2) <i>V. nakashimae</i> and <i>V. marina</i> does so by accumulating higher amount of K⁺, whereas <i>V. riukiuensis</i> and <i>V. luteola</i> does so by other mechanisms. 3) <i>V. luteola</i> avoids salt-shedding by allocating excess Na⁺ to newly expanded leaves. As the mechanisms of the tolerant species were different, they could be piled up in a single crop <i>via</i> classical breeding or by genetic engineering or genome editing.</p>

DOI： 10.1270/jsbbs.22012

Web of Science

Scopus

PubMed

CiNii Research

Language：Japanese   Publisher：Japanese Journal of Applied Physics  

Radioisotope tracer imaging is useful for studying plant physiological phenomena. In this study, we developed an autoradiography system with phosphor powder (ZnS:Ag), "Live-autoradiography", for imaging radioisotope dynamics in a living plant. This system visualizes the element migration and accumulation in intact plants continuously under a light environment. An imaging test was performed on point sources of 137Cs, with radioactivity of 10-100 kBq of being observed; this indicates satisfactory system linearity between the image intensity and the radioactivity of 137Cs. Moreover, dynamics imaging of 137Cs was performed on an intact soybean plant for four days. The serial images indicated 137Cs accumulation in the node, vein, and growing point of the plant. The developed system can be used for studying plant physiological phenomena and can be employed for the quantitative measurement of radionuclides.

DOI： 10.35848/1347-4065/ac2b50

Web of Science

Scopus

Language：English   Publishing type：Research paper (scientific journal)  

Radiocesium accumulated in the soil by nuclear accidents is a major environmental concern. The transport process of cesium (Cs+) is tightly linked to the indispensable plant nutrient potassium (K+) as they both belong to the group I alkali metals with similar chemical properties. Most of the transporters that had been characterized to date as Cs+ transporters are directly or indirectly linked to K+. Using a combinatorial approach of physiology, genetics, cell biology, and root uptake assay, here we identified two ATP-binding cassette (ABC) proteins, ABCG37 and ABCG33, as facilitators of Cs+ influx. A gain-of-function mutant of ABCG37 (abcg37-1) showed increased sensitivity to Cs+-induced root growth inhibition, while the double knockout mutant of ABCG33 and ABCG37 (abcg33-1abcg37-2) showed resistance, whereas the single loss-of-function mutants of ABCG33 and ABCG37 did not show any alteration in Cs+ response. In planta short-term radioactive Cs+-uptake assay along with growth and uptake assays in a heterologous system confirmed ABCG33 and ABCG37 as Cs+-uptake carriers. Potassium response and content were unaffected in the double-mutant background and yeast cells lacking potassium-uptake carriers transformed with ABCG33 and ABCG37 failed to grow in the absence of K+, confirming that Cs+ uptake by ABCG33 and ABCG37 is independent of K+. Collectively, this work identified two ABC proteins as new Cs+-influx carriers that act redundantly and independent of the K+-uptake pathway.

DOI： 10.1016/j.molp.2021.02.002

PubMed

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japanese Society of Plant Morphology  

<p>We have developed a system that can quantitatively analyze the dynamics of mineral elements in living plants by visualizing radioactive tracers moving within the plant. This system can visualize various types of radioactive tracers and track the dynamics of a wide variety of elements. Two types of systems have been developed according to the field of view. The macro-imaging system has a field of view of 10 x 20 cm with a resolution in the order of millimeters, whereas the microscopic-imaging system has a field of view of 600 x 600 µm with 100 µm resolution. Since these two systems use living plants for analysis, it is possible to change the plant growth environment during imaging and analyze plant responses to environmental changes. The visualization by this system is expected to be applied not only in the field of plant nutrition but also to various fields in bioscience such as plant morphology.</p>

DOI： 10.5685/plmorphol.33.9

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)  

Magnesium (Mg) is essential for many biological processes in plant cells, and its deficiency causes yield reduction in crop systems. Low Mg status reportedly affects photosynthesis, sucrose partitioning and biomass allocation. However, earlier physiological responses to Mg deficiency are scarcely described. Here, we report that Mg deficiency in Arabidopsis thaliana first modified the mineral profile in mature leaves within 1 or 2 days, then affected sucrose partitioning after 4 days, and net photosynthesis and biomass production after 6 days. The short-term Mg deficiency reduced the contents of phosphorus (P), potassium, manganese, zinc and molybdenum in mature but not in expanding (young) leaves. While P content decreased in mature leaves, P transport from roots to mature leaves was not affected, indicating that Mg deficiency triggered retranslocation of the mineral nutrients from mature leaves. A global transcriptome analysis revealed that Mg deficiency triggered the expression of genes involved in defence response in young leaves.

DOI： 10.3389/fpls.2020.00563

PubMed

Language：Japanese   Publisher：一般社団法人 日本土壌肥料学会  

DOI： 10.20710/dohikouen.66.0_149_1

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

<p>We updated our imaging system, namely real-time radioisotope imaging system (RRIS) to observe ³²P movement in large plants using a large size scintillator. In the previous version of RRIS, the view was limited by the size of a CsI (Tl) scintillator deposited on a fiber optic plate (FOS). However, owing to the high price and difficulty in handling of FOS, the view area was limited to 100×200 mm. In this study, we evaluated 5 large and low-cost plastic scintillators and showed that plastic scintillators can be used in RRIS for the quantitative analysis of ³²P. We also evaluated the resolution of the imaging system with plastic scintillator.</p>

DOI： 10.3769/radioisotopes.68.73

CiNii Books

Publishing type：Part of collection (book)  

© The Author(s) 2019. We have developed a real-time radioisotope imaging system (RRIS) to visualize ion transport in plants, and to measure radioactivity in living plants. To know the mechanisms of ion transport in plants, the use of living plants allows us to visualize ion movement in real time. In addition, the RRIS can analyze how a change to the plant environment affects ion transport. In this chapter, we will introduce some of the applications of the RRIS. We analyzed the effect of light on cesium, potassium, magnesium, phosphate, and calcium transport in plants using the RRIS. The results show that magnesium, potassium, and calcium transport in plants were not influenced by light. On the other hand, the amount of cesium and phosphate absorption in roots decreased after light-off. Moreover, the amount of phosphate transport from root to shoot also decreased after light-off.

DOI： 10.1007/978-981-13-3218-0_19

Scopus

J-GLOBAL

Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s10967-018-6102-z

Other Link： http://link.springer.com/content/pdf/10.1007/s10967-018-6102-z.pdf

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Magnesium deficiency can cause starch accumulation, photosynthesis inhibition and senescence particularly in young mature leaves. This study was performed to identify the initial process leading to leaf senescence under Mg deficiency.Gene expression in the young leaf was analyzed at days 2, 4, 5 of Mg deficiency using microarray analysis, and several Fe responsive genes were identified. Therefore, the effect of lowering Fe supply on gene expression and oxidative stress under Mg deficiency was evaluated.Transcriptome analysis revealed that 7 of the 30 most upregulated genes and 11 of the 30 most downregulated genes were Fe-responsive. Particularly, the upregulation of OsFER2 and downregulation of OsMIR and OsIRO2 hinted at the induction of excess Fe stress under Mg deficiency. Both lowering of Fe concentration in Mg-free solutions and resupply of Mg without modifying Fe concentrations at day 4 rescued leaves from senescence by inhibiting oxidative stress and normalising the expression of Fe-responsive genes. Meanwhile, Fe content was equal between control, Mg-deficient and Mg-resupplied plants.Mg shortage can induce excess Fe stress, which in turn causes oxidative stress before inhibition of photosynthesis. It is proposed that Mg deficiency disrupts a mechanism for storing toxic Fe ions into the vacuole in the expanding young leaf cells.

DOI： 10.1007/s11104-018-3658-x

Web of Science

Other Link： http://link.springer.com/content/pdf/10.1007/s11104-018-3658-x.pdf

Language：English   Publishing type：Research paper (scientific journal)  

Using the real-time radioisotope imaging system (RRIS), we present the carbon dioxide gas fixation process of a soybean plant applying the 14C-labeled gas. When 14CO2 gas was supplied to the selected mature leaf, the fixed carbon, photosynthate, was transferred and accumulated to the younger leaves preferentially within 24 h. When 14CO2 gas was supplied to the younger leaves, fixed carbon was hardly moved. In the case of the pods, fixed 14CO2 gas in the leaf was preferentially transferred to the closest pod.

DOI： 10.1007/s10967-018-6119-3

PubMed

Language：Japanese   Publisher：一般社団法人 日本土壌肥料学会  

DOI： 10.20710/dohikouen.64.0_57_1

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

We developed a real-time radioisotope imaging system (RRIS) technique that can nondestructively visualize the element absorption and transport process in plants, using not only positron emitters but also commercially available radioisotopes. In this study, we applied RRIS to analyze light effects on ion movement in rice plants. As tracers, Mg-28, P-32, and Ca-45 were used. During the first 5 h, dark/light cycle of 3/7 min were set up; the RRIS needs dark conditions during capturing. When the light was ceased 5 h after supplying each tracer, P-32 transport from root to shoot decreased immediately. In contrast, Mg-28 and Ca-45 transport did not change with light conditions. These results suggest that the P transport is dependent on water flow, whereas Mg and Ca transport are independent of water flow.

DOI： 10.1007/s10967-017-5193-2

Web of Science

Other Link： http://link.springer.com/content/pdf/10.1007/s10967-017-5193-2.pdf

Language：English   Publishing type：Research paper (scientific journal)  

Minerals and photosynthates are essential for many plant processes, but their imaging in live plants is difficult. We have developed a method for their live imaging in Arabidopsis using a real-time radioisotope imaging system. When each radioisotope,(22)Na,(28)Mg,(32)P-phosphate,(35)S-sulfate,(42)K,(45)Ca,(54)Mn and(137)Cs, was employed as an ion tracer, ion movement from root to shoot over 24 h was clearly observed. The movements of(22)Na,(42)K,(32)P,(35)S and(137)Cs were fast so that they spread to the tip of stems. In contrast, high accumulation of(28)Mg,(45)Ca and(54)Mn was found in the basal part of the main stem. Based on this time-course analysis, the velocity of ion movement in the main stem was calculated, and found to be fastest for S and K among the ions we tested in this study. Furthermore, application of a heat-girdling treatment allowed determination of individual ion movement via xylem flow alone, excluding phloem flow, within the main stem of 43-day-old Arabidopsis inflorescences. We also successfully developed a new system for visualizing photosynthates using labeled carbon dioxide,(14)CO2 Using this system, the switching of source/sink organs and phloem flow direction could be monitored in parts of whole shoots and over time. In roots,(14)C photosynthates accumulated intensively in the growing root tip area, 200-800 µm behind the meristem. These results show that this real-time radioisotope imaging system allows visualization of many nuclides over a long time-course and thus constitutes a powerful tool for the analysis of various physiological phenomena.

DOI： 10.1093/pcp/pcw056

PubMed

Language：English   Publishing type：Research paper (scientific journal)  

The differences in the transport characteristics in planta between potassium (K+) and caesium (Cs+) was investigated using their radionuclides, 42K+ and 137Cs+. A tracer experiment using nutrient solutions supplemented with 42K and 137Cs revealed that the ratio of the root's K+ uptake rate to its Cs+ uptake rate was 7-11 times higher than the K+:Cs+ concentration ratio in the solution, and the number was varied depending on the K concentration in the solution and also on the growth condition. After entering through the root tissues, the 42K+:137Cs+ ratio in the shoots was 4.28 times higher than the value in the roots. However, the 42K+:137Cs+ ratio in each leaf did not differ significantly, indicating that the primary transport of K+ and Cs+ in the shoots are similarly regulated. In contrast, among the radionuclides stored in the roots over 4h, 30% of the 42K+ was exported from the roots over the following hour, whereas only 8% of 137Cs+ was exported. In addition, within the xylem, K+ was shown to travel slowly, whereas Cs+ passed quickly through the roots into the shoots. In conclusion, our study demonstrated very different transport patterns for the two ions in the root tissues.

DOI： 10.1071/FP15245

PubMed

Publishing type：Part of collection (book)  

© The Author(s) 2016. Various radioisotope imaging techniques have been used at the Graduate School of Agricultural and Life Sciences, University of Tokyo, to analyze samples containing radiocesium (137 Cs and 134 Cs). There are two types of samples: (1) environmental samples contaminated by the fallout from the Fukushima Daiichi nuclear power plant accident, which contain relatively low concentrations of radiocesium and (2) laboratory samples from tracer experiments conducted at the radioisotope institution containing relatively high concentrations of 137 Cs. The first technique used to visualize radiocesium in soil and plants was radioluminography (RLG). RLG, which makes use of an imaging plate, has a dynamic range that is large enough to detect both environmental and tracer-added samples. To quantify radiocesium distributions, the samples were frozen and sliced before contact with the imaging plate. This freezing procedure after sampling is for preventing radiocesium movement during slicing and measurement of 137 Cs distribution. After slicing, two detection methods were employed: RLG and microautoradiography (MAR). MAR is the conventional and older method for imaging radioisotopes based on the daguerreotype process. We applied this method to frozen sections and obtained 137 Cs distributions at a higher resolution than with RLG. Following this, we employed a non-destructive method for imaging 137 Cs movement in a living plant. We developed the visualization technique called real-time radioisotope imaging system and then demonstrated 137 Cs movement from soil to rice plants using a chamber containing paddy soil, water, and rice plants. Lastly, 42 K obtained by 42Ar-42 K generation enabled a comparison between the movement of 137 Cs and 42 K. The mechanism of Cs transport has been reported to have some relationship with the K transport system, so experiments using both 137 Cs and 42 K would be useful for clarifying the mechanism in more detail.

DOI： 10.1007/978-4-431-55828-6_19

Scopus

Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s10967-015-4233-z

Other Link： http://link.springer.com/article/10.1007/s10967-015-4233-z/fulltext.html

J-GLOBAL

Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

DOI： 10.3769/radioisotopes.64.169

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The mechanisms underlying magnesium (Mg) uptake by plant roots remain to be fully elucidated. In particular, there is little information about the effects of Mg deficiency on Mg uptake activity. A Mg uptake kinetic study is essential for better understanding the Mg uptake system.We performed a Mg uptake tracer experiment in rice plants using (28) Mg.Mg uptake was mediated by high- and low-affinity transport systems. The K (m) value of the high-affinity transport system was approximately 70 mu M under Mg-deficient conditions. The Mg uptake activity was promoted by Mg deficiency, which in turn fell to the basal level after 5- min of Mg resupply. The induced uptake rate was inhibited by ionophore treatment, suggesting that an energy-dependent uptake system is enhanced by Mg deficiency.The Mg uptake changes rapidly with Mg conditions in rice, as revealed by a (28) Mg tracer experiment. This technique is expected to be applicable for Mg uptake analyses, particularly in mutants or other lines.

DOI： 10.1007/s11104-014-2197-3

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

In plant research, radioisotope imaging provides useful information about physiological activities in various tissues and elemental transport between plant organs. To expand the usage of imaging techniques, a new system was developed to visualize beta particles, x-rays and gamma-rays emitted from plant bodies. This real-time radioisotope imaging system (RRIS) visualizes radioactivity after conversion into light with a CsI(Tl) scintillator plate. Herein, the RRIS detection properties of the gamma-ray emitters (22)Na, (65)Zn, (86)Rb, (109)Cd and (137)Cs were evaluated in comparison with those of radioluminography (RLG) using an imaging plate. The lower quantitative detection limit (Bq mm(-2)) during a 15 min period ranged from 0.1 to 4, depending on the nuclide, similar to that of RLG. When the quantitative ability to detect radiation from various Arabidopsis tissues was analyzed, the quantitative capability in silique and the thick internode tended to be low. In an EGS5 simulation, beta particles were the greatest contributors to RRIS imaging of (22)Na, (86)Rb and (137)Cs, and low-energy x-rays contributed significantly to (65)Zn and (109)Cd detection. Thus, both self-absorption and air space between the sample and scintillator surface could impair quantitative RRIS imaging. Despite these issues, RRIS is suggested for quantitative time-course measurements of radionuclide motion within plants.

DOI： 10.1088/0031-9155/59/4/837

PubMed

Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

DOI： 10.3769/radioisotopes.63.227

J-GLOBAL

Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s10967-013-2462-6

Other Link： http://link.springer.com/article/10.1007/s10967-013-2462-6/fulltext.html

Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s10967-012-2131-1

Other Link： http://link.springer.com/article/10.1007/s10967-012-2131-1/fulltext.html

Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s10967-012-2130-2

Other Link： http://link.springer.com/article/10.1007/s10967-012-2130-2/fulltext.html