Jun Abe

The University of Tokyo, Edo, Tōkyō, Japan

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Publications (33)36.12 Total impact

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    ABSTRACT: Apoplasmic barriers in plants fulfil important roles such as the control of apoplasmic movement of substances and the protection against invasion of pathogens. The aim of this study was to describe the development of apoplasmic barriers (Casparian bands and suberin lamellae) in endodermal cells of Arabidopsis thaliana primary root and during lateral root initiation. Modifications of the endodermal cell walls in roots of wild-type Landsberg erecta (Ler) and mutants with defective endodermal development - scarecrow-3 (scr-3) and shortroot (shr) - of A. thaliana plants were characterized by light, fluorescent, confocal laser scanning, transmission and cryo-scanning electron microscopy. In wild-type plant roots Casparian bands initiate at approx. 1600 µm from the root cap junction and suberin lamellae first appear on the inner primary cell walls at approx. 7000-8000 µm from the root apex in the region of developing lateral root primordia. When a single cell replaces a pair of endodermal and cortical cells in the scr-3 mutant, Casparian band-like material is deposited ectopically at the junction between this 'cortical' cell and adjacent pericycle cells. Shr mutant roots with an undeveloped endodermis deposit Casparian band-like material in patches in the middle lamellae of cells of the vascular cylinder. Endodermal cells in the vicinity of developing lateral root primordia develop suberin lamellae earlier, and these are thicker, compared wih the neighbouring endodermal cells. Protruding primordia are protected by an endodermal pocket covered by suberin lamellae. The data suggest that endodermal cell-cell contact is required for the spatial control of Casparian band development. Additionally, the endodermal cells form a collet (collar) of short cells covered by a thick suberin layer at the base of lateral root, which may serve as a barrier constituting a 'safety zone' protecting the vascular cylinder against uncontrolled movement of water, solutes or various pathogens.
    Annals of Botany 05/2012; 110(2):361-71. · 3.45 Impact Factor
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    ABSTRACT: Silica deposition in two upland rice cultivars, IRAT 109 and Moroberekan, and one lowland rice cultivar, Koshihikari, were compared. X-ray microanalysis coupled with environmental scanning electron microscopy was used to examine fresh, unfixed, hydrated samples for analyses. The results showed silica deposition in seminal roots exclusively in endodermal cells. A clear basipetal increase in Si content was found in the endodermis of all cultivars. Comparison of silicification intensity between the three cultivars showed higher amounts of Si deposited in the endodermis of upland rice cultivars. This might be related to a higher drought resistance of these types of rice. In leaves, silica deposits were present in all epidermal cells with the highest concentration in silica cells. The amount of Si deposited in leaves was several times higher than in the root endodermis. No relationship between extent of leaf epidermal silicification was found when lowland and upland cultivars were compared.Key words: endodermis, environmental scanning electron microscope (ESEM), rice, root, silica deposits, X-ray microanalysis.
    Canadian Journal of Botany 02/2011; 77(7):955-960. · 1.40 Impact Factor
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    ABSTRACT: The combination of substrate materials and bacteria is an important factor affecting conversion technology for biological hydrogen production. We performed anaerobic hydrogen fermentation of apple pomace wastes using rhizosphere bacterial microflora of rice as the parent inoculum. In the vial test, the optimal condition for hydrogen fermentation was initial pH 6.0, 35 °C, and 73.4 g pomace per liter of medium (equivalent to 10 g-hexose/L). In the batch experiment (pH 6.0, temperature 35 °C) the hydrogen yield reached 2.3 mol-H2/mol-hexose. The time course of biogas production and PCR-DGGE analysis suggest that Clostridium spp. decomposed degradable carbohydrates rapidly and a part of the refractory carbohydrate (e.g. pectin) gradually in the apple pomace slurry. In addition to hydrogen, volatile fatty acids (VFAs) were produced in the anaerobic fermentation of apple pomace, which can be a substrate for methane fermentation. The rice rhizosphere can be a promising source of inoculum bacteria for hydrogen fermentation in combination with plant material waste like apple pomace.
    International Journal of Hydrogen Energy - INT J HYDROGEN ENERG. 01/2010; 35(14):7369-7376.
  • Breeding Science - BREEDING SCI. 01/2009; 59(1):87-93.
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    ABSTRACT: We performed an experiment of continuous anaerobic hydrogen fermentation as a pilot-plant-scale test, in which waste from a bread factory was fermented by microflora of rice rhizosphere origin. The community structure of microflora during anaerobic hydrogen fermentation was analyzed using PCR-DGGE, FISH, and quinone profiles. The relation of those results to hydrogen generation was discussed. Results show that a suitable condition was a reactor temperature of 35 °C, with HRT 12–36 h, volume load of 30–70 kg-CODCr/m3 day, and maximum hydrogen production rate of 1.30 mol-H2/mol-hexose. Regarding characteristics of microflora during fermentation, PCR-DGGE results show specific 16S rDNA band patterns; Megasphaera elsdenii and Clostridium sp. of the hydrogen-producing bacteria were identified. M. elsdenii was detected throughout the fermentation period, while Clostridium sp. of hydrogen-producing bacteria was detected on the 46th day. Furthermore, FISH revealed large amounts of Clostridium spp. in the sample. The quinone profile showed that the dominant molecular species of quinone is MK-7. Because Clostridium spp. belong to MK-7, results suggest that the quinone profile result agrees with the results of PCR-DGGE and FISH. Microflora in the rhizosphere of rice plants can be a possible resource for effective bacteria of biohydrogen production.
    International Journal of Hydrogen Energy. 01/2009;
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    ABSTRACT: Basic information about the root and root nodule structure of leguminous crop plants is incomplete, with many aspects remaining unresolved. Peanut (Arachis hypogaea) forms root nodules in a unique process. Structures of various peanut root types were studied with emphasis on insufficiently characterized lateral roots, changes in roots during their ontogenesis and root modification by nodule formation. Peanut plants were grown in the field, in vermiculite or in filter paper. The taproot, first-order and second-order lateral roots and root nodules were analysed using bright-field and fluorescence microscopy with hand sections and resin sections. Three root categories were recognized. The primary seminal root was thick, exhibiting early and intensive secondary thickening mainly on its base. It was tetrarch and contained broad pith. First-order lateral roots were long and thin, with limited secondary thickening; they contained no pith. Particularly different were second- and higher-order lateral roots, which were anatomically simple and thin, with little or no secondary growth. Unusual wall ingrowths were visible in the cells of the central part of the cortex in the first-order and second-order lateral roots. The nodule body was formed at the junction of the primary and lateral roots by the activity of proliferating cells derived originally from the pericycle. Two morphologically and anatomically distinct types of lateral roots were recognized: long, first-order lateral roots, forming the skeleton of the root system, and thin and short second- and higher-order lateral roots, with an incomplete second state of endodermal development, which might be classified as peanut 'feeder roots'. Formation of root nodules at the base of the lateral roots was the result of proliferating cell divisions derived originally from the pericycle.
    Annals of Botany 04/2008; 101(4):491-9. · 3.45 Impact Factor
  • Plant Production Science - PLANT PROD SCI. 01/2008; 11(2):232-237.
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    ABSTRACT: A pot experiment was performed to examine the effects of flooding on growth, yield and aerenchyma development in adventitious roots of four kenaf ( Hibiscus cannabinus L.) cultivars. Three flooding treatments consisting of early season flooding (30 days after planting), mid-season flooding (60 days after planting) and late season flooding (90 days after planting), as well as non-flooding control were used in the present study. The results show that soil flooding significantly increased plant height by 108 and 107% over control in early flooding and mid-flooding, respectively. Early flooding significant decreased the number of leaves and leaf area of whole plant and core dry weights by 15, 19 and 20% over non-flooding control, respectively. Soil flooding did not show any significant effect on plant height and number of leaf among cultivars, but did for leaf area, leaf dry weight and core dry weight. Early season and mid-season flooding significant decreased root dry weight in soil by 71 and 49% over non-flooded control, respectively. No adventitious roots developed in non-flooded control. Adventitious roots located in water above soil surface had dry weight of 18, 11 and 6 g plant<sup>-1</sup> in early season, mid season and late season flooding, respectively. No significant difference in root dry weight located in soil and root dry weight located in water above soil surface were observed among cultivars. Aerenchyma formed in adventitious roots when the plant was subjected to flooding and was more developed in roots located in water above the soil surface as compared to roots located in soil. All the cultivars formed aerenchyma in their adventitious roots with variation among cultivars. Soil flooding significantly decreased fiber yield by 13% in non-flooded control in early season flooding treatments. However, mid-season and late season flooding did not show any significant difference on fiber yield in comparison with control. The cultivars was not significantly difference on fiber yield in the present experiment.
    Asian Journal of Plant Sciences. 01/2008;
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    ABSTRACT: The productivity of upland rice in Japan as well as in the world is low and unstable owing to scarce and unpredictable rainfall. The objective of this study was to examine whether agronomic methods could enhance grain yield of upland rice. Four field experiments were conducted from 2001 to 2003 in Nishitokyo, Japan, under upland conditions with different water supplies, in order to quantify the effects of deep tillage combined with deep placement of manure (50-cm depth), straw mulch (6 t ha−1), or their combinations on the growth and grain yield of rice. Mulch kept surface soil moisture higher than without mulch even at reproductive stage, and it increased yield to the greatest extent under the most favourable conditions with much rainfall before heading (i.e., 2003). Deep tillage with deep placement of manure induced deep root proliferation and higher nitrogen uptake, increasing biomass production, and panicle number, and consequently grain yield was enhanced under the two lowest yielding environments with less rainfall before heading. Rice plants with deep tillage with deep manure application without mulch tended to have lower leaf water potential and higher diffusion resistance during drought, and negative effects on grain filling and harvest index in some experiments compared with the control. When deep tillage with deep placement of manure was combined with mulching in two experiments in 2002 and 2003, grain yield always enhanced compared with the control (P < 0.10, 6.0 t ha−1 versus 5.4 t ha−1 on average), suggesting their synergetic mechanisms for yield increase and stabilization. The results showed that deep tillage or mulching can improve grain yield of rice under drought-prone rainfed upland conditions in a temperate climate on an Andosol, and their combination had more consistent and greater positive effects.
    Soil and Tillage Research. 01/2007;
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    ABSTRACT: The experiment was conducted to investigate the formation of oxidative stress and the development of anti-oxidative enzymes in two barley genotypes differing in anoxia tolerance. Waterlogging led to significant reduction in root and shoot weight, green leaf area and tillers per plant, but tolerant Xiumai 3 was much less reduced than sensitive Gerdner. Malondialdehyde (MDA) content, an indicator of membrane lipid peroxidation, significantly increased in Gerdner when the plants were subjected to waterlogging, but remained little changed in Xiumai 3. Superoxide dismutase (SOD) activity was increased with waterlogging treatment and the sensitive cultivar had higher activity than the tolerant one during the experimental duration. At early stage of waterlogging treatment, both peroxidase (POD) and catalase (CAT) activities significantly increased in Xuimai 3, while obviously decreased in Gerdner. Moreover, both cultivars showed substantial increase in both POD and CAT with the progress of waterlogging exposure. Glutathione reductase (GR) activity was increased in both tolerant- and sensitive cultivars under waterlogging. It may be assumed from the current results that SOD activity appears to be not a constraining factor limiting the scavenging of ROS, and it is the change of POD and CAT activity under waterlogging that determine the status of oxidative stress. The difference between genotypes in waterlogging tolerance could be distinguished from the changed patterns of these enzymatic activities.
    Acta Physiologiae Plantarum 01/2007; 29(2):171-176. · 1.31 Impact Factor
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    ABSTRACT: Bacteria in the rhizosphere influence plant growth and interact with plant roots. Microscopy and culture method have been used for studies of microorganisms of the rhizosphere, but these methods are insufficient for evaluation because most rhizosphere bacteria are viable but non-culturable (VBNC). Bacteria in the rhizosphere of rice cultivated in Andosol lowland and upland fields were analyzed in this study using PCR-DGGE and FISH, in combination with modified pretreatments. Results show that the two methods with the pretreatments, more than conventional methods, provided a rapid and simple analysis of rhizosphere bacteria. The 16S rDNA band pattern of bacteria in the rhizosphere obtained using PCR-DGGE indicated different species composition of bacterial community in the two ecosystems and greater diversity of bacteria in the rhizosphere in upland field. Sequencing of major 16S rDNA bands identified Bacterium A35 and Clostridium bifermentans as dominant bacteria in the rhizosphere of rice in lowland fields and Klebsiella planticola and Bacillus fusiformis in upland fields. Furthermore, FISH observation indicated the predominance of gram-positive low GC bacteria in both rhizospheres and a higher proportion of Clostridium spp. in lowland fields, which is consistent with results of PCR-DGGE analysis. The results suggest that the bacteria in the rice rhizosphere can be changed depending on aerobic and anaerobic conditions of fields. It is expected to apply the PCR-DGGE and FISH to agricultural field experiments as reliable methods to evaluate the rhizosphere bacteria.
    01/2007;
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    Plant Production Science - PLANT PROD SCI. 01/2007; 10(3):357-360.
  • Plant Production Science - PLANT PROD SCI. 01/2007; 10(4):423-429.
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    Plant Production Science - PLANT PROD SCI. 01/2007; 10(3):270-276.
  • Plant Production Science - PLANT PROD SCI. 01/2007; 10(2):219-231.
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    Plant Production Science - PLANT PROD SCI. 01/2007; 10(1):3-13.
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    ABSTRACT: The spatial distribution of lateral roots in the soil is an important factor influencing water and nutrient absorption. However, lateral root development has rarely been studied in detail, especially concerning morphological variations, mainly because such examinations are both time-consuming and laborious. We measured the number and length of all first-order lateral roots on the seminal roots of maize (Zea mays L.) and wheat (Triticum aestivum L.) to investigate variations in linear frequency and length. This was conducted with reference to species, root types, and positions on their parental roots. Although the linear frequency of first-order lateral roots varied along the root axis in maize, the variation was not as great as in wheat. Variations were found in the length of lateral roots among plant species, root types, and positions on their parental root axes. Such variations in the length of lateral roots along the root axes were caused by differences in the elongation period of lateral roots rather than those in the elongation rate. Additionally, we examined the effects of soil drying on lateral root development. As a response to soil drying, the length of lateral roots varied depending on the period they were placed under the stressed condition. Moderate soil drying could also accelerate the elongation of some lateral roots. Variations in the length of first-order lateral roots and their responses to soil drying could help distribute their tips thoroughly throughout the soil. This might be adaptive for water absorption for root system development when resources are limited.
    Physiologia Plantarum 04/2006; 127(2):260 - 267. · 3.66 Impact Factor
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    ABSTRACT: Deep root development, which is important for the drought resistance in rice (Oryza sativa L.), is a complex trait combining various root morphologies. The objective of this study was to elucidate genotypic variation in deep root development in relation to morphological indicators such as vertical root distribution and root growth angle. Two experiments were conducted: one on upland fields, and one in pots and fields. In experiment 1, the root systems of six rice cultivars on upland fields were physio-morphologically analyzed under different water regimes (irrigated and intermittent drought conditions during panicle development). In experiment 2, cultivar differences in root growth angles were evaluated with 12 cultivars using the basket method under irrigated conditions. No cultivar×environment interactions were found for total root length or deep root length between irrigated and drought conditions in experiment 1. This suggests that constitutive root growth, which is genetically determined, is important for deep root development under intermittent drought conditions during reproductive stage. Among root traits, the deep root ratio (i.e., deep root weight divided by total root weight) was most closely related to deep root length under both water regimes. This suggested that vertical root distribution constitutively affects deep root length. Significant genotypic variation existed in the nodal root diameter and root growth angle of upland rice in experiment 2. It was considered that genotypes with thick roots allocated more assimilates to deep roots through root growth angles higher to the horizontal plane on upland fields. This is the first report on genotypic variation in the root growth angle of rice on upland fields. It should prove useful for rough estimations of genotypic variation in the vertical root distribution of upland rice because root growth angle is rapidly and easily measured.
    Plant and Soil 01/2006; 287(1):117-129. · 3.24 Impact Factor
  • Plant Production Science - PLANT PROD SCI. 01/2006; 9(3):249-255.
  • Plant Production Science - PLANT PROD SCI. 01/2006; 9(4):422-434.