Keitaro Tanoi

Keitaro Tanoi
The University of Tokyo | Todai · Faculty and Graduate School of Agriculture and Life Sceince

Ph.D

About

187
Publications
18,025
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2,689
Citations
Additional affiliations
February 2012 - present
The University of Tokyo
Position
  • Professor (Associate)

Publications

Publications (187)
Preprint
Magnesium (Mg) homeostasis is critical for maintaining many biological processes, but little information is available to comprehend the molecular mechanisms regulating Mg concentration in rice ( Oryza sativa ). To make up for the lack of information, we aimed to identify mutants defective in Mg homeostasis through a forward genetic approach. As a r...
Article
The front cover image is based on the Original Article Visualization of phosphorus re‐translocation and phosphate transporter expression profiles in a shortened annual cycle system of poplar by Yuko Kurita et al., https://doi.org/10.1111/pce.14319.
Article
Magnesium is an important nutrient for plants, but much is still unknown about plant Mg2+ transporters. Combining with the structural prediction of AlphaFold2, we used mutagenesis and 28Mg uptake assay to study the highly conserved “GMN” motif of Arabidopsis thaliana MRS2-1 (AtMRS2-1) transporter. We demonstrated that the glycine and methionine in...
Preprint
In the phloem, various solutes such as photosynthates, mineral nutrients, or toxic elements move from the source organs to sinks. One of them is the root. While this process may mediate significant quantities of solutes delivered to the root, it is unclear how the solutes are distributed along the root axis. To elucidate the distributing pattern of...
Article
Nutrient distribution within the soil is generally heterogeneous. Plants, therefore, have evolved sophisticated systemic processes enabling them to optimize their nutrient acquisition efficiency. By organ-to-organ communication in Arabidopsis thaliana, for instance, iron starvation in one part of a root drives the upregulation of a high-affinity ir...
Article
K+/Na+ homeostasis is important for land plants, particularly under salt stress. In this study, the structure and ion transport properties of the high-affinity K+ uptake transporter (HKT) of the liverwort Marchantia polymorpha were investigated. Only one HKT gene, MpHKT1, was identified in the genome of M. polymorpha. Phylogenetic analysis of HKT p...
Article
The long‐term behavior of radiocesium (137Cs) activity concentrations in forest ecosystems and their downstream impacts remain important issues in the deciduous broadleaf forests of Fukushima, Japan following the Fukushima Daiichi Nuclear Power Plant accident. To predict 137Cs cycling and discharge in the forest ecosystem, it is important to unders...
Article
Phosphorus (P) is an essential macronutrient for plant growth. In deciduous trees, P is remobilized from senescing leaves and stored in perennial tissues during winter for further growth. Annual internal recycling and accumulation of P is considered an important strategy to support vigorous growth of trees. However, the pathways of seasonal re‐tran...
Article
Full-text available
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 metal with similar chemical properties. Most of the transporters that had been characterized to date as Cs⁺ t...
Article
Zinc (Zn) is a nutritionally essential metal element, but excess Zn in the environment is toxic to plants. Autophagy is a major pathway responsible for intracellular degradation. Here, we demonstrate the important role of autophagy in adaptation to excess Zn stress. We found that autophagy-defective Arabidopsis thaliana (atg2 and atg5) exhibited ma...
Article
Full-text available
Excessive amounts of metal ions in soil are toxic for most plant species, yet metal can also facilitate plant survival by elemental defense against herbivores and pathogens. Zinc and cadmium hyperaccumulation in Arabidopsis halleri is known to be effective for the defense against natural enemies. The allotetraploid species A. kamchatica, derived fr...
Article
Full-text available
The objective of this study was to determine the radiocesium transfer rates of pigs fed haylage contaminated with low levels of cesium at different growth stages. We measured the body weight of juvenile and adult pigs during the treatment period to confirm their health status. We also performed pig blood hematologic and biochemical analyses at both...
Article
We studied seasonal changes in radiocesium (137Cs) activity and potassium concentrations in current-year leaves and branches of Pinus densiflora (naturally regenerated saplings), Cryptomeria japonica (planted saplings) and Quercus serrata (planted saplings and coppice shoots) in Fukushima, Japan. We collected current-year shoots from 10 individuals...
Article
It is known that cesium ion, Cs⁺, is strongly sorbed to micaceous minerals. However, the desorption of Cs⁺ at a trace sorption level with time in the presence of different salt ions is not well understood. In this study, we conducted long-term sorption and desorption experiments of Cs⁺ with illite and vermiculite at room temperature to study the ef...
Article
Full-text available
In rice, the OsHKT1;5 gene has been reported to be a critical determinant of salt tolerance. This gene is harbored by the SKC1 locus, and its role was attributed to Na+ unloading from the xylem. No direct evidence, however, was provided in previous studies. Also, the reported function of SKC1 on the loading and delivery of K+ to the shoot remains t...
Article
Full-text available
Both inorganic fertilizer inputs and crop yields have increased globally, with the concurrent increase in the pollution of water bodies due to nitrogen leaching from soils. Designing agroecosystems that are environmentally friendly is urgently required. Since agroecosystems are highly complex and consist of entangled webs of interactions between pl...
Article
Full-text available
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 Ara...
Preprint
(1) the research conducted, including the rationale Phosphorus (P) is an essential macronutrient for plant growth. In deciduous trees, P is remobilized from senescing leaves and stored in perennial tissues during winter for further growth. To clarify how deciduous trees utilize the internal P through a year, seasonal re-translocation routes and the...
Preprint
Full-text available
Grafting is an important technique in agriculture to obtain several good traits such as high disease tolerance and high yield by exchanging root system. However, the underlined cellular processes to compensate the wound damage and repair tissues were largely unknown. We analyzed two graft combinations: Nicotiana benthamiana ( Nb ) homograft as a co...
Preprint
Full-text available
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 metal with similar chemical properties. Most of the transporters that had been characterized to date as Cs+ t...
Article
Full-text available
Arsenic contamination is a major environmental issue as it may lead to serious health hazard. Reduced trivalent form of inorganic arsenic, arsenite, is in general more toxic to plants compared with the fully oxidized pentavalent arsenate. The uptake of arsenite in plants has been shown to be mediated through a large subfamily of plant aquaglyceropo...
Article
Full-text available
Background Stable cesium ( ¹³³ Cs) naturally exists in the environment whereas recently deposited radionuclides (e.g., ¹³⁷ Cs) are not at equilibrium. Stable cesium has been used to understand the long-term behavior of radionuclides in plants, trees and mushrooms. We are interested in using ¹³³ Cs to predict the future transfer factor (TF) of radio...
Article
Radiation imaging technology is a promising research tool in plant science. In this review, we introduce the principles and applications of radiation imaging technology for plant science that is currently available. Specifically, static imaging methods such as radioluminography and microPIXE, and also dynamic imaging methods such as real-time radio...
Article
Radiocesium contamination of forests has been a severe problem after the Fukushima Daiichi Nuclear Power Plant accident in 2011. Bed logs of Konara oak (Quercus serrata Murray), used for mushroom cultivation, were an economically important product from the forests prior to their contamination. One of the potential countermeasures to reduce radioces...
Article
Full-text available
Soil provides most of the essential elements required for the growth of plants. These elements are absorbed by the roots and then transported to the leaves via the xylem. Photoassimilates and other nutrients are translocated from the leaves to the maturing organs via the phloem. Non-essential elements are also transported via the same route. Theref...
Chapter
In this study, we examine the radioactivity monitoring data derived from Fukushima prefecture. The Japanese government has established very strict limits for radiocesium in food since April 2012 (100 Bq/kg for general food). The Fukushima prefectural government inspected foods and found that most of the agricultural products in Fukushima did not co...
Preprint
Full-text available
Arsenic contamination is a major environmental issue as it may lead to serious health hazard. Reduced trivalent form of inorganic arsenic, arsenite, is in general more toxic to plants compared with the fully oxidized pentavalent arsenate. The uptake of arsenite in plants has been shown to be mediated through a large subfamily of plant aquaglyceropo...
Article
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 o...
Article
Synchrotron μ-XRF and autoradiography complementally revealed the different behavior of arsenic and phosphorus in Pteris vittata L. at a high spatial resolution in its living state. We found that P. vittata develops several sequestration mechanisms for As from important biological functions at different growth stages. Some of them relate to the act...
Article
We investigated the vertical ¹³⁷Cs distribution in soil among five sod culture orchards with different soil textures over six years after 2011, when ¹³⁷Cs fallout was released by the Fukushima Daiichi Nuclear Power Plant accident, to confirm the long-term ¹³⁷Cs downward-migration into soil. At each orchard, soil cores were collected to a depth of 3...
Chapter
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 af...
Chapter
To breed a low Cs rice variety, it is important to clarify the mechanism of Cs transport in a plant. In the present report, we found a difference in Cs distribution in rice cultivars using a ¹³⁷Cs tracer experiment. In addition, the difference was also found in Cs distribution of each leaf position among the same rice cultivars. There has been no r...
Chapter
We have investigated the redistribution dynamics of radiocesium deposited after the nuclear power station accident in March 2011 in a forested catchment located in North Fukushima over a four-year period (2012–2015). At the catchment scale, ¹³⁷ Cs accumulation decreased drastically by 50% of the estimated initial accumulation during the first 2 yea...
Chapter
On June 28, 2011, 26 pigs were rescued from the alert area, 17 km northwest of the Fukushima Daiichi Nuclear Power Plant, where radiation levels were approximately 1.9–3.8 μSv/h. The pigs were transferred outside of the radiation alert area to the Animal Resource Science Center (ARSC), The University of Tokyo. It was confirmed by the farm owner tha...
Book
This open access book presents the findings from on-site research into radioactive cesium contamination in various agricultural systems affected by the Fukushima Daiichi Nuclear Power Plant accident in March 2011. This third volume in the series reports on studies undertaken at contaminated sites such as farmland, forests, and marine and freshwater...
Article
This study investigated the effect of Cs-137 absorbed from the upper part (surface of leaves and husk) of rice plants and its accumulation in grains. Cesium-137 content in brown rice plants sprayed with Cs-137 onto the plant surface before ear emergence, flowering, and grain filling stages were 5, 109, and 76 Bq/kg, respectively. Comparison of Cs-1...
Article
Full-text available
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 sup...
Article
We updated real-time radioisotope imaging system (RRIS) to study photosynthate movement in a large-size plant. Earlier, we used a CsI (Tl) scintillator attached to a fiber optic plate (FOS) to convert radiation into light. However, the scintillator size was fixed as 10 cm × 10 cm, which was too small to observe the entire plant. Moreover, the high...
Article
Contamination of agricultural products by resuspended matter remains a concern in the highly contaminated areas. Radiocesium concentration of spinach cultivated with non-contaminated soil was low in the decontaminated areas, but high in the contaminated areas. The washed plants had relatively lower radiocesium concentration than the unwashed plants...
Article
Full-text available
Aims 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. Methods Gene expression in the young leaf was analyzed at days 2, 4, 5 of Mg deficiency using microarray anal...
Article
Main conclusion: The Mg2+ uptake system in Arabidopsis roots is Gd3+- and Fe2+-sensitive, and responds to a changing Mg2+ concentration within 1 h with the participation of AtMRS2 transporters. Magnesium (Mg2+) absorption and the mechanism regulating its activity have not been clarified yet. To address these issues, it is necessary to reveal the c...
Article
To investigate the contribution of soil animals to the cesium-137 (¹³⁷Cs) concentration change in the course of the litter decomposition process, we conducted litter bag experiments in forest sites located about 50 km northwest from the Fukushima Dai-ichi Nuclear Power Plant. To control the influence of soil animals of different size, two different...
Article
Radionuclides released by the accident at the Fukushima Daiichi Nuclear Power Plant included ¹³⁷Cs (Cesium-137) and ¹³⁴Cs (Cesium-134), which were deposited on land as a result of fallout and concentrated in the uppermost 2–5 cm of the soil. In this study, river monitoring was conducted for 3.5 years to quantify dissolved and particulate radiocesiu...
Article
Full-text available
The absorption and dynamics of Cs in crops can be measured and examined using not only ¹³⁷Cs but also ¹³³Cs, a stable isotope which can be analyzed in a regular laboratory. When ¹³³Cs is used, however, the concentration of added ¹³³Cs must be set higher than that in the soil solution due to the detection sensitivity of inductively coupled plasma op...
Article
Full-text available
The high affinity K⁺ transporter 1;4 (HKT1;4) in rice (Oryza sativa), which shows Na⁺ selective transport with little K⁺ transport activity, has been suggested to be involved in reducing Na in leaves and stems under salt stress. However, detailed physiological roles of OsHKT1;4 remain unknown. Here, we have characterized a transfer DNA (T-DNA) inse...
Article
Full-text available
To ensure successful plant reproduction and crop production, the spatial and temporal control of the termination of the floral meristem must be coordinated. In Arabidopsis, the timing of this termination is determined by AGAMOUS (AG). Following its termination, the floral meristem underdoes gynoecium formation. A direct target of AG, CRABS CLAW (CR...
Article
Radioactive materials, primarily radiocaesium (¹³⁴Cs+¹³⁷Cs), were released into the environment by the Fukushima Dai-ichi Nuclear Power Plant accident in March 2011. The proportion of the soybean plants that had an activity concentration of radiocaesium over 100 Bq/kg was higher than that of other crops. To examine the reason why the activity conce...
Article
Occurrence of radiocesium in food has raised sharp health concerns after nuclear accidents. Despite being present at low concentrations in contaminated soils (below μM), cesium (Cs(+) ) can be taken up by crops and transported to their edible parts. Such a plant capacity to take up Cs(+) from low concentrations has notably affected the production o...
Article
Water deficit caused by global climate changes seriously endangers the survival of organisms and crop productivity, and increases environmental deterioration 1,2. Plants' resistance to drought involves global reprogramming of transcription, cellular metabolism, hormone signalling and chromatin modification 3-8. However, how these regulatory respons...
Article
Salt tolerance quantitative trait loci analysis of rice has revealed that the SKC1 locus, which is involved in a higher K+ /Na+ ratio in shoots, corresponds to the OsHKT1;5 gene encoding a Na+ -selective transporter. However, physiological roles of OsHKT1;5 in rice exposed to salt stress remain elusive, and no OsHKT1;5 gene disruption mutants have...
Article
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, ²⁸Mg, ³²...
Article
Full-text available
Short day length-induced alteration of potassium (K) localization in perennial trees is believed to be a mechanism for surviving and adapting to severe winters. To investigate the relationship between cesium (Cs) and K localizations, a model tree poplar, hybrid aspen T89, was employed. Under short day length conditions, the amount of 137Cs absorbed...
Article
Full-text available
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, 22Na, 28Mg, 32P-phosphate, 35S-sulphate, 42K, 45Ca, 54Mn, and 137Cs, was employed as an ion tracer,...
Article
Radioactive substances were released into the environment after the nuclear accident at the Fukushima Daiichi Nuclear Power Station; this led to the contamination of the soil at Fukushima Prefecture. Mixing of organic matter with soil during plowing is known to influence radiocesium (134Cs and 137Cs) absorption by crops. However, the effect of mixi...
Chapter
Various radioisotope imaging techniques have been used at the Graduate School of Agricultural and Life Sciences, University of Tokyo, to analyze samples containing radiocesium (137Cs and 134Cs). There are two types of samples: (1) environmental samples contaminated by the fallout from the Fukushima Daiichi nuclear power plant accident, which contai...
Chapter
Contamination of food and animal products by radioactive cesium represents an important potential route of exposure in the human food chain. Therefore, following the Fukushima Daiichi nuclear power plant accident, the development of solutions for radiocesium contamination is a serious social issue in Japan. Most farm animals are kept in closed barn...
Chapter
Appropriate treatment is urgently needed for farm and ranch waste that has been contaminated with radioactive cesium from the Fukushima Daiichi nuclear power plant accident. We previously developed an aerobic ultra-high temperature fermentation (more than 115 °C) method to inhibit intestinal infectious diseases. Fermented waste (compost), in which...
Chapter
We performed consecutive field trials of rice cultivation to reduce radiocesium (134Cs and 137Cs) absorption by rice in a partially decontaminated paddy soil in the Iitate Village in Fukushima prefecture, Japan. People had evacuated this area because of the high levels of radioactive contamination caused by the nuclear disaster in 2011 at the Fukus...
Chapter
In the present chapter, I present the distribution of radiocesium in wild boars as well as the official monitoring data of wild boars from Fukushima. After the nuclear accident in 2011, the radiocesium contamination levels in wild boars from most places in Fukushima Prefecture exceeded 100 Bq/kg. The most contaminated wild boars were observed in So...
Chapter
The accident at the Fukushima Daiichi Nuclear Power Plant in March 2011 emitted 1.2 × 1016 Bq of cesium-137 (137Cs) into the surrounding environment. Radioactive substances, including 137Cs, were deposited onto forested areas in the northeastern region of Japan. 137Cs is easily adsorbed onto clay minerals in the soil; thus, a major portion of 137Cs...
Article
Full-text available
Cesium adsorption/desorption experiments for various clay minerals, considering actual contamination conditions in Fukushima, were conducted using the 137Cs radioisotope and an autoradiography using imaging plates (IPs). A 50 μl solution containing 0.185 ~ 1.85 Bq of 137Cs (10−11 ~ 10−9 molL−1 of 137Cs) was dropped onto a substrate where various mi...