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

DOI： 10.1111/jac.12507

Web of Science

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

DOI： 10.1016/j.envexpbot.2020.104089

Web of Science

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

DOI： 10.3389/fpls.2019.01417

Web of Science

PubMed

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

DOI： 10.1128/MRA.00820-18.

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

DOI： 10.1016/j.rhisph.2016.12.005

Web of Science

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

DOI： 10.1080/15592324.2016.1274483

Web of Science

PubMed

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

DOI： 10.1128/genomeA.00868-16

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

DOI： 10.1080/00380768.2013.791807

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

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

Authorship：Lead author,　Corresponding author   Language：Japanese  

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s11104-010-0581-1

Authorship：Lead author   Language：Japanese  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s11104-009-0058-2

Authorship：Lead author   Language：Japanese  

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

DOI： 10.1111/j.1469-8137.2008.02518.x

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/aob/mcl216

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

Previous studies have suggested that the deep roots of sesbania (Sesbania sesban) function less efficiently in water acquisition than those of pigeon pea (Cajanus cajan) despite similar rooting depths. To investigate this phenomenon, both species were grown in a vertically split-root system. The top soil was watered at two-day intervals and the bottom soil was kept wet. Fifty-seven days after sowing, the watering to the top soil was withheld and the water uptake was monitored in both the layers. At any given rate of transpiration, the water influx rate per unit root surface (WIR/RS) was higher in the top soil than in the bottom soil in sesbania, despite the greater availability of water in the latter. By contrast, in pigeon pea, the WIR/RS was higher in the bottom soil than in the top soil. In sesbania, aerenchyma tissue was observed only in the cortex of the roots in the bottom soil. On the other hand, aerenchyma tissue was scarcely observed in pigeon pea roots, suggesting that the presence of aerenchyma tissue led to the reduced WIR/RS of sesbania roots in the bottom soil. Thermal image analysis showed that the stomata of sesbania leaves did not respond to water shortage. Instead, the sesbania leaves were shed in order to avoid desiccation, further reducing the potential to extract water. We therefore conclude that the water-extraction ability of deep roots was lower in sesbania than in pigeon pea as a result of aerenchyma formation and leaf shedding.

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

In rainfed lowland rice fields, developing hardpan soil layers must be important to pool rainfall, but during drought that also restricts water movement from below it. We investigated whether the hardpan can maintain a contrast of deuterium/hydrogen isotopic composition (delta D) in soil water under field condition. The experimental site was at Rajshahi in north-west Bangladesh. The hardpan soil layers had developed around 0.2 m soil-depth in the field. Soil water from either above or below the hardpan was collected non-destructively with porous cups installed into the field. Using an isotopic ratio mass spectrometer, delta D value of each water sample was determined. During the sampling period, the field surface varied from water-saturated to unsaturated status with rainfall event. While the delta D values fluctuated by the influence of rainfall, significant differences in the delta D values were always detected between above and below the hardpan, revealing heterogeneity in the delta D values persisted with the hardpan. The effect of hardpan on retention of the delta D signature was further confirmed in a laboratory experiment using intact soil columns collected from a paddy field at Nagoya University. The natural delta D signature in rainfed lowland rice field may be useful to identify certain genotypes that demonstrate in situ capability of water acquisition from below the hardpan through delta D analysis of the xylem sap.

Authorship：Lead author   Language：Japanese  

陸上植物の根は，むき出しの「根」で存在するよりも，共生微生物の菌根菌が共生した状態の「菌根」で存在しているのが普通である．最も普遍的にみられるのがVA 菌根であり，この菌根が形成されると宿主植物のリン獲得能が向上することはよく知られている．しかし，多くの生態系で植物の成長を律速しているのはリンよりもむしろ窒素であるが，VA 菌根菌が宿主植物の窒素栄養に関与しているかどうかは議論が続いてきた．私たちは最近，アンモニアを吸収したVA 菌根菌は速やかに宿主にその窒素を提供するのに，硝酸を吸収した場合には自らが利用するだけで宿主に受け渡さない，という選択的な窒素供給現象を見いだした．本稿では，VA 菌根菌が宿主植物の窒素栄養にどのように関与するのかについて，私たちの研究を紹介しつつ，過去の研究の問題点について議論する．

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1111/j.1365-3040.2005.01360.x

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

The morphological plasticity of roots in nutrient-enriched patches of soil is regarded as an adaptive response in plants, but its functional efficiency is still debatable. We examined whether the efficiency is dependent upon the patch size, or the amount of phosphate (P) supplied in maize (Zea mays L.). Two levels of P-input (high and low) and three patch sizes (large, medium and small) were used in various combinations in containers filled with soil. Irrespective of the P-inputs, P uptake and biomass were greatest in large patches together with root proliferation restricted to the soil inside patches, indicating that the effect of P-patch size was stronger than the amount of P supplied. Due to the fine root proliferation (about 0.5mm-width) of higher specific root length, the root length promoted was not accompanied by more biomass investment inside the patches. For the medium and small patches, such a localized root proliferation disappeared, resulting in impaired plant growth with limited P acquisition. It was concluded that the efficiency of the root plasticity on P acquisition depends on the size of P patches more strongly than the inputs.

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

It is not known why sweet potato (Ipomoea batatas) cultivated in tropical regions tolerates acid soil. Here, we report the involvement of mycorrhizal symbiosis in this tolerance. Plants were grown in root-boxes filled with either acidic soil (pH 4.2) or the same soil amended with lime (pH 5.2) for 30-d in a growth chamber. In the inoculated treatments, the percentage of root length colonized by Gigaspora margarita was not affected by soil pH (23±9% at pH 4.2 vs. 30±12% at pH 5.2). The root and shoot dry weights of the non-mycorrhizal plants at pH 4.2 were 27 and 35%, respectively, of those at pH 5.2. The root and shoot dry weights of the mycorrhizal plants at pH 4.2 were 70 and 51% of those at pH 5.2. Growth promotion in mycorrhizal plants was significant only at pH 4.2 (2-fold increase in whole plant dry weight), but not at pH 5.2. As a result, no significant difference was detected in whole plant dry weight between the mycorrhizal plants at pH 4.2 and non-mycorrhizal plants at pH 5.2. The mycorrhizal plants at pH 4.2 showed reduced toxic symptoms of Mn (brown specks on mature leaves) and Al (poor root growth) compared to non-mycorrhizal ones, but tissue concentrations of P, K and Ca did not increase in mycorrhizal plants. We assume that the mycorrhizal colonization can reduce toxic effects of those elements while the exact mechanisms should be further investigated.

Language：Japanese  

自然に学ぶものづくり2004. 積水化学工業株式会社.

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Language：English  

Language：Japanese  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Hydraulic lift is a movement of water between soil layers contrasting in water potential through plant root systems. We expected that an introduction of deep-rooted plants into intercropping systems could provide an opportunity for the associated crops to utilize water from deep in the soil layers through hydraulic lift. A stable hydrogen isotope (deuterium) was used to investigate this possibility in a field experiment conducted at the Zambia National Irrigation Research Station. Maize (Zea mays) plants were grown adjacent to the deep rooting legumes, pigeon pea (Cajanus cajan) and sesbania (Sesbania sesban), whose roots accessed groundwater having the deuterium/hydrogen isotope ratios (deltaD) different from those of rainfall. We hypothesized that the deltaD values of xylem waters from shallow-rooted maize would become closer to those of groundwater when hydraulic lift occurred, and this would be affected by the distance between the maize and the legumes. The maize near pigeon pea showed deltaD values closer to those of groundwater while the maize at a distance did not. However, we could not detect such a distance-dependence in maize plants grown adjacent to sesbania. Based on the field trial, a glasshouse experiment was implemented for the pigeon pea-maize association. The plants were grown in a split-root container with an air gap between the two soil layers. The pigeon pea roots were allowed to develop in the bottom soil injected with D2O while the maize roots were confined in the top soil. Immediately after the injection, a higher D concentration above the level of natural occurrence was detected in xylem waters from each of the maize plants, confirming that pigeon pea lifted water from the bottom and transferred it to the maize. Moreover, the water supply from the pigeon pea to the maize was enhanced by the shading treatment on the pigeon pea, implying the possibility of regulating the function of the hydraulic lift. It is concluded that at least pigeon pea c

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Both peanuts and pigeonpeas are believed to utilize non-labile phosphate (P) due to the dissolving abilities of their root exudates, in which the mycorrhizal interaction is rarely considered. We examined a hypothesis that such effective P acquisition would not appear without the mycorrhizal function. First, mycorrhizal responses of peanuts and pigeonpeas were compared with soybeans or a non-mycorrhizal species of yellow lupin in a P-limited soil amended with a mixture of three non-labile P sources (Fe-P, Al-P, and Ca-phytate). Inoculation with Gigaspora margarita greatly increased P uptake in pigeonpeas (10-fold) and peanuts (6-fold), more than in soybeans (3-fold), indicating greater mycorrhizal dependency in both these plants. Second, the mycorrhizal responses of peanuts and pigeonpeas were compared in a soil amended with three P sources individually. P uptake responses were significant, and similar for all the P sources in pigeonpeas. In peanuts, the response was significant for both Al-P and Fe-P, but not for Ca-phytate because of greater P uptake in the non-inoculated plants, implying a direct utilization of Ca-phytate by peanuts. Third, interactive effects of the pigeonpeas' rhizosphere and extraradical hyphae were investigated in a compartment container, where root exudate movement as well as hyphal penetration into the compartment soil, amended with Al-P, was controlled. A significant increase in P uptake was found only when both the exudates and hyphae were permitted access into the compartment soil, suggesting the importance of the interactive effect. We concluded that the mycorrhiza can accelerate P acquisition by the plants from non-labile sources in soil through interaction between the roots and hyphae. It is a novel finding that peanuts can utilize Ca-phytate without mycorrhiza, but the mechanism is still unclear.

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

Previous greenhouse and field studies have shown arbuscular mycorrhizal (AM) plants usually have greater P uptake and growth when raised in undisturbed soil compared to soil disturbed between plantings, such as by tillage. We report here for the first time that AM fungi able to stimulate shoot P uptake in experimental comparisons to non-mycorrhizal plants differ in their ability to bring about similar responses in undisturbed soil compared to disturbed soil. This outcome indicates a difference in functional character between the two stimulation processes. Three isolates of AM fungi were tested for growth promotion of maize (Zea mays L.) in pots in a soil disturbance experiment that included non-mycorrhizal controls. All three fungi colonized roots well and promoted shoot P uptake compared to non-inoculated controls, but only Glomus mosseae was able to stimulate growth in undisturbed soil compared to disturbed soil. This effect was seen when Glomus mosseae was alone or in combination with Gigaspora margarita. However, the presence of Glomus aggregatum in combination with Glomus mosseae prevented any stimulation, presumably due to domination by Glomus aggregatum. The ability of AM fungi to be beneficial to plants in comparison to non-mycorrhizal situations likely relates to the spread of mycelium in the soil and the capacity for nutrient transfer to the root. The ability of an AM fungus to promote growth in undisturbed soil appears to be related to these features and, in addition, a capacity for persistence and retention of functional capacity of the extraradical mycelium from one plant generation to the next.

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

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

The deuterium/hydrogen isotope ratios (deltaD) of xylem waters from pigeon pea (Cajanus cajan) and sesbania (Sesbania sesban) plants grown in semi-arid Zambia were investigated to know the seasonal variation in water sources for those crops. The study was conducted at a field site in the Zambia National Irrigation Research Station from November 2000 until April 2001. We measured the deltaD values of xylem waters exuded by both of the legumes, in addition to those of rainfall and groundwater. This was done by use of an isotope ratio mass spectrometer. While the deltaD values of rainfall fluctuated considerably, those of groundwater were almost constant throughout the experimental period. The deltaD values obtained from the xylem waters from both species also fluctuated, suggesting the influence of water from rainfall. The tap roots of both of the plants reached at least 2 in below the soil surface, where groundwater was available. However, xylem waters from sesbania always showed deltaD values closer to those of the groundwater, as compared to values measured in pigeon pea. This implies that sesbania. has a greater dependency on groundwater for its water supply than pigeon pea. During the dry season, only pigeon pea exuded xylem sap despite its smaller dependency on groundwater. Therefore, it was hypothesized that pigeon pea could more actively absorb water from drying surface layers, while sesbania was less able. This water from surface layers would result in a diluted groundwater composition in xylem waters of pigeon pea. We have shown that deltaD analysis for xylem waters can aid in the understanding of the function of deep rooting systems of crops grown in fields.

Language：English  

"In: Nakatani, M. & Komaki, K eds., Potential of Root Crops for Food and Industrial Resources. pp136-138."

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"In: Nakatani, M. & Komaki, K eds., Potential of Root Crops for Food and Industrial Resources. pp132-135."

Language：Japanese  

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

In contrast to cereals or other crops, legumes are known to acidify the rhizosphere even when supplied with nitrates. This phenomenon has been attributed to N-2 fixation allowing excess uptake of cations over anions; however, as we have found previously, the exposure of the shoot to illumination can cause rhizosphere acidification in the absence of N-2 fixation in cowpea (Vigna unguiculata L. Walp). In this study, we examined whether the light-induced acidification can relate to photosynthetic activity and corresponding alterations in cation-anion uptake ratios. The changes of rhizosphere pH along the root axis were visualized using a pH indicator agar gel. The intensity of pH changes (alkalization/acidification) in the rhizosphere was expressed in proton fluxes, which were obtained by processing the images of the pH indicator agar gel. The uptake of cations and anions was measured in nutrient solution. The rhizosphere was alkalinized in the dark but acidified with exposure of the shoots to light. The extent of light-induced acidification was increased with leaf size and intensity of illumination on the shoot, and completely stopped with the application of photosynthesis inhibitor. Although the uptake of cations was significantly lower than that of anions, the rhizosphere was acidified by light exposure. Proton pump inhibitors N,N'-dicyclohexyl carbodimide and vanadate could not stop the light-induced acidification. The results indicate that light-induced acidification in cowpea seedlings is regulated by photosynthetic activity, but is not due to excess uptake of cations.

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Regulation of phosphorus solubilization by light conditions on shoot in legumes

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

0919-2182

Language：Japanese  

平成11年度名古屋大学大気水圏科学研究所共同研究報告書

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

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

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Plant growth is sometimes restricted with soil compaction under no-tillage conditions, although undisturbed soils are favorable to arbuscular mycorrhizal (AM) fungi of a symbiont. We examined growth responses of the pigeon pea (Cajanus cajan (L.) Millsp.) to soil disturbance and inoculation with an AM fungus (Gigaspora margarita Pecker & Hall) in a pot experiment. The AM fungal inoculum was added to the soil and wheat was grown. After 6 months the shoot of wheat was removed and the soil was either disturbed or remained undisturbed. Subsequently, pigeon pea was grown and harvested after 3 months. The colonization and spore density of Gigaspora were significantly greater in undisturbed soil than in disturbed soil. Undisturbed soil showed higher penetrometer resistance and resulted in impaired shoot growth of the pigeon pea with lower shoot-to-root (S/R) ratio than disturbed soil. However, inoculation with the AM fungus reduced the stress impact of undisturbed soil on the pigeon pea without affecting the soil resistance and S/R ratio. A possible reason for reducing the stress impact was increase in specific root length, rather than P inflow with the AM formation. It is a novel finding that AM formation in undisturbed soil could promote root elongation despite the fact that soil was seriously compacted.

Language：Japanese  

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

Plant phosphorus demand affects root responses to locally applied phosphorus in wheat: Plasticity in specific root length and acid phosphatase exudation

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

The morphological responses of root systems to localized colonization by endophytes is not well understood. We examined the responses of lateral roots to the arbuscular mycorrhizal (AM) fungus Gigaspora margarita Becker & Hall inoculated locally into the soil. Peanut (Arachis hypogaea L.) and pigeon pea (Cajanus cajan (L.) Millsp.) were examined. Root boxes filled with nutrient-poor soil in were inoculated in one half with the fungus and in the other half with a sterilized inoculum. Responses were apparent after 30 days but not after 20 days. Overall, lateral root development was more advanced in inoculated soil. This was clearly observed for 2nd- and 3rd-order lateral roots, but less clear for Ist-order lateral roots in both species, although percentage of colonized root length was higher in Ist-order lateral roots. Whilst in peanut the responses were clearly evident at the level of lateral roots initiated on more proximal parts of the tap root axis, they occurred on more distal parts in pigeon pea. We conclude that plants under nutrient-poor conditions give priority to mycorrhizal roots when partitioning assimilation products within the root system. Thus, AM formation may induce local morphological alteration of root systems.

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Modification of root system morphology caused by the inoculation of arbuscular mycorrhizal fungus (Gigaspora margarita Pecker & Hall) was evaluated in peanut (Arachis hypogaea L.). Peanut plants were grown for 16 days in root boxes placed in a growth chamber with natural light. Inoculum of the fungus was uniformly mixed with the soil in root boxes, whereas in others, the soil was uninoculated to serve as a control. In each root system, the tap root axis was divided into 10-mm sections, where lateral roots remained intact, to evaluate the difference in lateral root development along the tap root. Two-way ANOVA in which the variation sources were divided into the inoculation treatment and section of tap root axis, showed significant effects of the inoculation on lateral root development. As for the root number, the effect was promotive for the 1st order lateral roots but inhibitive for the 2nd order ones, and as for the individual root length, inhibitive for the former but was not detected for the latter. Our conclusion is that the inoculation caused changes in root system morphology of peanut through lateral root development on the tap root, where the responses were different between Ist and 2nd order lateral roots.

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

The distribution of arbuscular mycorrhizal colonies was assessed in a peanut (Arachis hypogaea L.) root system at early growth stage. Arbuscular mycorrhizal fungus (Gigaspora margarita Pecker & Hall) was uniformly inoculated into non-sterilized soil. Peanut plants were grown in root boxes filled with the soil for 16 days inside a growth chamber. Approximately 66% of the total length of the mycorrhizal colonies was found on the Ist order lateral roots, while the rest was observed on the 2nd ones. In contrast, the tap root was scarcely colonized. On the Ist order lateral roots, regardless of the root length, it was evident that the frequency of the mycorrhizal colonies increased acropetally toward the root apex especially in the relatively aged roots that initiated on the proximal portion of tap root axis. In those lateral roots, the highest frequency of the mycorrhizal colony occurrence was recognized in the most apical part of the root, while many of relatively long colonies were found a little behind the root apex. However, the trend became unclear gradually in the relatively younger lateral roots initiated on the more distal potion of tap root axis. These facts clearly showed that in the Ist order lateral roots, the distribution and growth of mycorrhizal colonies are closely related with their initiating positions along tap root axis.

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

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Language：Japanese

根系と根圏環境

Language：Japanese

Language：Japanese

Language：Japanese

Event date： 2021.3

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2021.3

Presentation type：Poster presentation  

Country：Japan  

Event date： 2020.9

Language：English   Presentation type：Oral presentation (general)  

Event date： 2020.9

Language：English   Presentation type：Oral presentation (general)  

Event date： 2020.9

Language：English   Presentation type：Oral presentation (general)  

Event date： 2020.9

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2020.3

Language：English   Presentation type：Poster presentation  

Event date： 2018.9

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2018.9

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2017.9

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2016.3

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2015.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：つくば国際会議場   Country：Japan  

Event date： 2015.9

Language：Japanese   Presentation type：Poster presentation  

Venue：信州大学長野キャンパス   Country：Japan  

Event date： 2013.9

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2011.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：山口大学吉田キャンパス   Country：Japan  

Event date： 2011.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：山口大学吉田キャンパス   Country：Japan  

Event date： 2011.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：山口大学吉田キャンパス   Country：Japan  

Event date： 2010.8

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Country：Japan  

Event date： 2009.11

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2009.11

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2009.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2008.4

Language：English   Presentation type：Poster presentation  

Event date： 2008.4

Language：English   Presentation type：Poster presentation  

Event date： 2006.10

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2006.10

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2006.10

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2005.5

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Country：Japan  

Event date： 2005.3

Language：Japanese   Presentation type：Oral presentation (invited, special)  

"こどもの城, 東京都渋谷区"

Event date： 2004.6

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

"中部大学リサーチセンター, 春日井市"

Event date： 2001.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan