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Disturbances caused by invasive ungulates alter soil environments markedly and can prevent ecosystem recovery even after eradication of the ungulates. On oceanic islands, overgrazing and trampling by feral goats has caused vegetation degradation and soil erosion, which can alter soil chemistry. To understand the effects of the changes on plant performance, we conducted a laboratory experiment to assess herbaceous species growth under various soil conditions with phosphorous, nutrients, and acidity. Subsoil was collected from Nakodo-jima in the northwest Pacific. Six herbaceous species dominating the island were grown in soils with three levels of added CaCO3 and P2O5 and two levels of added KNO3. After 4 weeks of growth, the total dry plant weight was significantly lower with no added P2O5, regardless of the addition of KNO3. Three species weighed more under P2O5 and KNO3 addition in high-pH soil, whereas the remaining three weighed less. Our results indicated that herbaceous species growth is limited primarily by phosphorous availability; the limitation is dependent on soil pH, and the trend of dependency differs among species. This implies that ecosystems with extreme disturbances cannot recover without improving the soil chemistry. [ABSTRACT FROM AUTHOR]

Restoration of species-rich semi-natural grassland requires not only a seed source but also appropriate soil properties. In Europe, approximately 10 years are required for the properties of fertilized soils to reach suitable conditions and be considered successfully restored. However, restoration may require additional time in Japan because heavier precipitation causes leaching of basic cations from soils, resulting in soil acidification; volcanic ejecta also forms active Al and Fe hydroxides with high phosphate sorption. Within this context, we aimed to answer the following questions: i) whether and how the impacts of fertilization remain in the soil properties after half a century in Japan; and ii) how fertilization affects the restoration of semi-natural grasslands in Japan. We investigated the vegetation and soil properties of a Zoysia japonica pasture improved half a century ago with a single application of fertilizer and an adjacent semi-natural grassland (native pasture) in Japan, and found the following: (1) the two pastures had similar dominance of Z. japonica, but differed in the species composition; (2) the improved pasture exhibited lower species richness than the native pasture; (3) soil nutrients, including N, P, K, Mg, and Ca, were higher in the improved pasture than in the native pasture; and (4) many chemical properties of the soils were associated with species composition; namely, the vegetation on nutrient-rich soil had more alien species and fewer native species. We conclude that a single dose of fertilization can affect soil properties in semi-natural grasslands over half a century in Japan, leading to species loss and changing the species composition. We suggest that fertilized soils under grazing in Japan may require more than half a century to restore the nutrients to suitable levels for the establishment of a species-diverse grassland. [ABSTRACT FROM AUTHOR]

Selective removal of lignin and other recalcitrant compounds, collectively registered as acid-unhyrolyzable residue (AUR), results in bleaching of leaf litter, but the importance of bleaching in decomposition processes on forest soil has not been fully evaluated. The aims of this study were to elucidate the occurrence of bleached area in decomposing leaf litter and to compare chemical composition between bleached and nonbleached portions in a subtropical forest in Japan. Field incubation of leaf litter was performed over an 18-month period with the litterbag method. The decomposition processes during the first 9 month were characterized by the relatively rapid mass loss and increase of bleached area, whereas the mass loss was slowed down and the bleached area decreased thereafter. Mass loss of leaf tissues was faster and AUR content was lower in bleached than in nonbleached portions, indicating the acceleration of mass loss in bleached leaf tissues by the selective decomposition of recalcitrant compounds. The decrease in carbonyl-C in the bleached portions was associated with the increase of extractable nitrogen. The results suggest that the bleaching plays a dominant role in the transformation and turnover of organic compounds and nitrogen in decomposing leaf litter. [ABSTRACT FROM AUTHOR]

Microbes inhabiting the phyllosphere encounter harmful ultraviolet rays, and must develop adaptive strategies against this irradiation. In this study, we screened bacterial isolates originating from the phyllosphere of various plants which harbored absorbers of ultraviolet A (UVA), a wavelength range which is recognized as harmful to human skin. Of the 200 phyllosphere bacterial isolates we screened, methanol extracts from bacterial cells of seventeen isolates absorbed wavelengths in the range of 315–400 nm. All of the UVA-absorbing strains belonged to Methylobacterium species based on 16S ribosomal RNA gene sequences, suggesting that cells of this bacterial genus contain specific UVA-absorbing compounds. When cells of a representative Methylobacterium strain were extracted using various solvents, UVA absorption was observed in the extracts obtained using several aqueous solvents, indicating that the UVA-absorbing compounds were highly polar. A compound was purified using solid columns and HPLC separation, and comparative analysis revealed that the absorption strength and spectrum of the compound were similar to those of the known UVA filter, avobenzone. The compound was also verified to be stable under UVA exposure for at least 480 min. Based on these results, the UVA-absorbing compound harbored by Methylobacterium has potential to be used as a novel sunscreen ingredient. [ABSTRACT FROM AUTHOR]

To conserve indigenous natural ecosystem and help in the recovery of natural vegetation on Nakoudojima Island, which is a subtropical oceanic island in Ogasawara Islands in Japan, we clarified the mechanisms of the changes in soil chemical properties as affected by soil erosion and seabird activities on the island. Under grassland vegetation where influence of feral goat (exotic species) had been severe, the chemical properties of surface soils with a thickness of 5 cm were variable even in a small area of 0.375 km 2 ; pH(H 2 O) value range between 4.6 and 6.9, total C content range between 0.36 and 5.62%, total N content range between 0.03 and 0.45%, exchangeable acidity range between 0.5 and 50 mmol c kg − 1 , and plant-available phosphate (Bray II P) range between 0.4 and 170 mg P 2 O 5 100 g − 1 . By clarifying soil profile characteristics under natural and disturbed vegetation and distribution patterns of these soils on the island, the changes in the soil chemical properties were reasonably assigned to the effect of soil erosion caused by feral goats for increased soil exchangeable acidity and decreased soil pH (mainly found in inland area) and to the effect of seabird activities for increased Bray II P and soil exchangeable acidity and decreased soil pH (mainly found in outer rim area with high altitude). It was also clarified that the high soil exchangeable acidity was significantly related to the low productivity of plant biomass for these plots ( P < 0.01). Soil erosion would have removed surface soils having weak acidity and exposed subsoils having strong acidity to the ground surface, resulting in inhibition of plant growth and delay of vegetation recovery. Based on the findings obtained in the present study, several options were proposed to stop soil erosion and to recover the vegetation, although careful preliminary examination would be necessary for applying them. [ABSTRACT FROM AUTHOR]

To evaluate organic carbon (OC) accumulation processes in peat deposits in tropical mangrove ecosystems, solid-state 13 C cross-polarization and magic angle spinning nuclear magnetic resonance signals were measured to determine the OC compositions of decomposed leaves and roots. These account for a large majority of mangrove litters and mangrove peat in a coral reef-type Rhizophora forest on Pohnpei Island, Federated States of Micronesia. Radiocarbon dating was also used to understand the sources of peat deposits at each depth. The mass loss rate of mangrove leaves during 1-year litterbag incubation was much higher than that of roots. These mass loss rates are expected to be affected by the varying chemical characteristics of leaves and roots and the different aerobic/hydrological conditions present in the two litter types during decomposition. The decomposability of individual OC components also varied markedly between leaf and root litters. Significant increases in aryl-C/ O -alkyl-C and aliphatic-C/ O -alkyl-C ratios and minor increases in the aryl-C/aliphatic-C ratio during leaf decomposition implied that O -alkyl-C was more labile than aryl- and aliphatic-C and that aliphatic-C was also slightly more decomposable than aryl-C, but not significantly so, in leaf litters on the forest floor. Regarding roots, a stable aryl-C/ O -alkyl-C ratio during decomposition suggested that aryl- and O -alkyl-C components did not differ greatly in decomposability in the peat deposit, while the minor increase in the aliphatic-/ O -alkyl-C ratio and the substantial decrease in the aryl-/aliphatic-C ratio with decomposition implied that aliphatic-C was more recalcitrant than aryl- and O -alkyl-C in the peat. The OC compositional properties were quite homogenous throughout the peat profile, and 14 C dating mostly indicated modern, which suggest that large amounts of mangrove roots penetrate to at least 80 cm depth. These findings provide quantitative and qualitative insights into the potential importance of very high production of mangrove fine roots for OC accumulation in peat in tropical mangrove ecosystems. [ABSTRACT FROM AUTHOR]

Aluminum (Al) accumulators are widely distributed in the plant kingdom but phylogenetic implications of internal Al detoxification mechanisms are not well understood. We investigated differences in the characteristics of Al accumulation (i.e., accumulation potential, chemical form, and localization) in three woody Al accumulators, Symplocos chinensis (Lour.) Druce var. leucocarpa (Nakai) Ohwi f. pilosa (Nakai) Ohwi (Symplocaceae, Ericales), Melastoma malabathricum L., and Tibouchina urvilleana Cogn. (both Melastomataceae, Myrtales). The order of Al accumulation potential under hydroponic conditions was S. chinensis ≈ M. malabathricum > T. urvilleana. Oxalate was at least partly involved in the internal Al detoxification mechanisms in leaves of all three Al accumulators, based on a correlation analysis between Al and organic acid in water and 0.02 mol·L−1 HCl extracts and the 27Al nuclear magnetic resonance spectra of intact leaves. However, the Al forms in the leaves were not simple Al-ligand complexes in a specific cell structure. Al localization in leaf sections differed among the three species. Extremely high levels of Al were found in trichomes of the lower epidermis in leaves of T. urvilleana. These data illustrate that woody Al-accumulating angiosperms have independently developed various internal Al-tolerance mechanisms in which oxalate plays a significant role. [ABSTRACT FROM AUTHOR]

Carbon dynamics during litter decomposition have been described in a variety of forest ecosystems and provided insights into carbon flow in soils. To quantitatively assess how decomposition processes vary between litter types, solid-state C cross-polarization and magic-angle spinning nuclear magnetic resonance (CPMAS NMR) technique was applied to analyze conifer (cedar, cypress) and hardwood (chinquapin, beech, oak, birch) litter which had degraded during a 3 year litterbag experiment throughout Japan. The results were used to identify compositional changes and estimate decomposition constants ( k values) in exponential equations. Total litter and carbon type mass losses during decomposition varied significantly between litter types, being affected by the initial physicochemical litter quality. Concomitant increases and decreases in carbonyl and O/N-alkyl C compositions, respectively, were observed for all litter types, but aromatic and aliphatic C dynamics were less consistent. In hardwoods, [aromatic/aliphatic C ratio] was generally stable during decomposition, suggesting that, in hardwoods, the decomposabilities of aromatic and aliphatic C were similar. In the conifers, an increasing [aromatic/aliphatic C ratio] during decomposition suggested that aromatic C was more recalcitrant than aliphatic C. These results suggest that different decomposition processes between litter types might be related to different aromatic and aliphatic C behaviors, as affected by lignin stability and lipid leachability and biosynthesis. Variations in the k values for total litter and carbon types were not obvious between litter types, although the mass loss patterns differed significantly. The k values estimated in this study may contribute to predictions of soil carbon dynamics and the validation of carbon compartment models in forest ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: The genesis of a 40-cm-thick buried Holocene humic soil horizon in a 6-m-high sequence near Towada volcano, Japan, was examined by dating stable, plant-derived humin particles by AMS-based radiocarbon (14C), and by analyzing stable carbon isotope ratios (δ13C), phytolith composition, and soil chemical properties. The AMS dating yielded calibrated ages ranging from 7570–7679 to 6180−6313calyr BP. We obtained a strong correlation (r=0.99, ***p<0.001) between sample depth and the mean age. The (now buried) humic soil was formed by the incremental accumulation of tephric loess and aeolian dust at a constant rate of ~30mm per century for at least 1200years. Whilst the soil surface was slowly rising, graminaceous vegetation was supplied at a constant rate so that developmental upbuilding pedogenesis ensued. The soil was buried and isolated by the fall of the Towada-Chuseri tephra about 6200calyr BP. Thus the tephra-soil sequence near Towada volcano represents both developmental and retardant upbuilding pedogenesis. [Copyright &y& Elsevier]

We investigated 10 soils from six states in the United States to determine the relationship between potentio-metric titration derived soil surface charge and the concentration of water-extractable P (WEP). Phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy was used to determine the chemical speciation of soil P. The surface charge value at the native soil pH was correlated to the WEP concentration, indicating that electrostatic interactions are involved in determining soil phosphate solubility. The titration curves were fit to a two-site Langmuir model and analysis showed that the native pH surface charge was accounted for by the low pH Type Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. site, attributed to positively charged metal (oxy)hydroxides. The 31P NMR data indicated that 98% of the inorganic form of P was composed of orthophosphate species and 95% of the organic P was composed of the P monoester class compounds. The inorganic orthophosphate form of P was directly related to the total soil P content, suggesting that external fertilizer inputs control the level of this form of soil P. In contrast, P monoester class compound content was not related to total soil P content, suggesting that organic soil P is controlled by P cycling independent of external P inputs. The 31P NMR speciation data indicated that the inorganic orthophosphate, pyrophosphate, and DNA P concentrations in the soils were significantly associated with oxalate-extractable AI and Fe concentrations, which further demonstrates that metal (oxy)hydroxides are important surfaces where P species are interacting with soils. [ABSTRACT FROM AUTHOR]

We quantitatively clarified the early humification processes on Japanese cedar and Hinoki cypress forest floors by using a litterbag experiment and the solid-state C CPMAS NMR technique. There was no significant effect on litter mass loss during early humification between both coniferous litters regardless of the shape of their needles. Carbon composition in both litters showed similar trends during early humification. A/ O-A as a humification index was low, around 0.6, in both litters throughout the experiment period although 60% of litter mass was lost. Coniferous litter incubated for 3 years might not be well-humified and would be susceptible to physical fragmentation. Carbon mass loss rates in conifers were in the following order: O-alkyl > aliphatic > aromatic > carbonyl carbons, differing with hardwoods. Conifers had concomitantly higher and lower mass loss rates of aliphatic and aromatic carbons than hardwoods. Soil organic carbon (SOC) accumulated in topsoil for conifers had relatively high and low contents of aliphatic and aromatic carbons than that for hardwood. These compositional differences of SOC among forests could be caused by the high and low supply rates of aliphatic and aromatic carbons from litter to topsoil. Consequently, initial litter nature and humification processes can affect the compositional qualities of SOC accumulated in soil. [ABSTRACT FROM AUTHOR]

We isolated an antimicrobial compound from the aerial tissue of Geranium carolinianum and identified it as ethyl 3, 4, 5-trihydroxy benzoate (ethyl gallate) by 1H-NMR and 13C-NMR and gas chromatography–mass spectrometry. The antimicrobial activity of ethyl gallate against three potato pathogens was assayed by the paper disk method. The activity against Ralstonia solanacerum, Streptomyces scabies, and Streptomyces acidiscabies was observed at concentrations >200, >300, and >300 µg disk−1, respectively. These results suggest that the antimicrobial activity of Geranium carolinianum against soil-borne plant disease pathogens is partly related to ethyl gallate. [ABSTRACT FROM AUTHOR]

Mineral imbalance in high-input agricultural ecosystems has become an acute concern in many developed countries. Relapse into low-input agricultural ecosystems, however, will cause mineral stresses to crops, resulting in reduced food productions. Under such natural soil conditions, some endemic plants can tolerate the mineral stresses because they have evolved to adapt to the stresses. Numerous studies have been conducted to clarify the chemistry of the mineral elements of interest in rhizosphere and to utilize the tolerant mechanisms in plants. In this chapter, the authors reviewed the research progress on molecular scale mechanisms of Fe-deficiency, Al-toxicity, and P-deficiency stresses in soils and their tolerances by plants. In low Fe-availability conditions, two Fe-acquisition mechanisms of plants have been clarified: enhanced Fe dissolution in rhizosphere by secreted proton/reductants/chelators followed by reduction of Fe3+ to Fe2+ and specific uptake of Fe2+ (Strategy I) and Fe dissolution by secreted hexadentate Fe3+-transporting molecule (phytosiderophore) by forming Fe3+-phytosiderophore complex followed by specific uptake of the complex (Strategy II). Two tolerant mechanisms against high Al-toxicity of soils have been reported: exclusion of Al from cytoplasm (exclusion mechanism) and detoxification of Al in plants (internal detoxification mechanism). Phosphorous acquisition mechanisms of plants from low P-availability soils would be (1) alteration of root architecture, (2) secretion of organic acids, (3) secretion of phosphatase, and (4) enhanced expression of P transporter on roots. Some of the molecular mechanisms for the expression of the tolerances and their application to the genetic improvement are also reviewed. [ABSTRACT FROM AUTHOR]

Abstract: Three representative allophanic Andisols in Japan were evaluated by solid-state 13C, 27Al, and 29Si nuclear magnetic resonance (NMR) and stable isotopic ratio of carbon (δ13C). The solid-state cross polarization magic angle spinning (CPMAS) 13C NMR spectra were effective in characterizing crude soil C without any chemical treatment when soil C content was >100 g C kg−1. Aliphatic, O-alkyl, and carbonyl C were relatively abundant in the uppermost horizons, whereas aromatic C was concentrated in the subsurface horizons, showing its persistence and tolerance to degradation in subsurface horizons. Contribution ratios of C4-plant-derived C (mainly from Miscanthus sinensis) on the total CRC4 which were evaluated from δ13C value, were 35% to 42%, 59% to 62%, and 50% to 53% in subsurface horizons, and 12%, 23%, and 48% in uppermost horizons, for the three soils. The decline in CRC4 values in the uppermost horizons could be an effect of recent vegetation. Solid-state 27Al and 29Si NMR revealed that most part of the tetrahedral Al in volcanic glass had already weathered into octahedral Al and a large amount of allophanic constituents (allophane, imogolite, allophane-like constituents including protoimogolite) was formed in B horizon within the past 25,000 14C y. Allophanic constituents determined by 29Si NMR were compared with those dissolved by acid-oxalate, and differences between them were discussed. [Copyright &y& Elsevier]

Abstract: Fulvic acids play an important role in the behavior of metals and hydrophobic organic chemicals in soil and water environments. The isolation and purification of the fulvic acids have been difficult to achieve, however, because these compounds are soluble in both alkaline and acidic solution, resulting in difficulty of dehydration and demineralization. We propose here a new procedure for isolating fulvic acids as precipitates. Our procedure includes pH-adjustment of the fulvic acid solution to weakly acidic to neutral pH range (4 to 7). In an Andisol, recoveries of the fulvic acids we prepared by precipitation at equilibrium pH of 5.0 were 86% (dissolved total organic carbon basis) and 97% (absorbance basis, 400 nm), whereas recoveries of fulvic acids adsorbed on XAD-8 resin (hydrophobic fulvic acids) were 14% and 28%, respectively. Recoveries of the fulvic acids were further increased in our procedure by adding Al. The mechanism forming the precipitates includes a complexation reaction of carboxylic groups of the fulvic acids with Al (ligand exchange reaction); this mechanism is identical to that for the retention of fulvic acids in many soils. Therefore, it is likely that our preparation procedure is appropriate for separating the fulvic acids stabilized in soils. Solid-state cross polarization and magic angle spinning 13C nuclear magnetic resonance spectra showed that the fulvic acids prepared by our precipitation procedure were relatively rich in O-alkyl carbons and poor in aromatic and alkyl carbons compared with those forms from the hydrophobic fulvic acids adsorbed on XAD-8 resin. A new scheme for preparing the hydrophobic and hydrophilic fulvic acids is also proposed here. The hydrophilic fulvic acids are likely to maintain high solubilities in water even after the formation of complexes with metals and may influence on their behavior. [Copyright &y& Elsevier]

Abstract: Cyanamide is a multifunctional agrochemical used, for example, as a pesticide, herbicide, and fertilizer. Recent research has revealed that cyanamide is a natural product biosynthesized in a leguminous plant, hairy vetch (Vicia villosa). In the present study, gas chromatography–mass spectrometry (GC–MS) equipped with a capillary column for amines was used for direct quantitative determination of cyanamide. Quantitative signals for (14N2)cyanamide, (15N2)cyanamide (internal standard for stable isotope dilution method), and m-(trifluoromethyl)benzonitrile (internal standard for correcting errors in GC–MS analysis) were recorded as peak areas on mass chromatograms at m/z 42 (A 42), 44 (A 44), and 171 (A IS), respectively. Total cyanamide content, (14N2)cyanamide plus (15N2)cyanamide, was determined as a function of (A 42 + A 44)/A IS. Contents of (14N2)cyanamide and (15N2)cyanamide were then calculated by multiplying the total cyanamide content by A 42/(A 42 + A 44) and A 44/(A 42 + A 44), respectively. The limit of detection for the total cyanamide content by the GC–MS analysis was around 1ng. The molar ratio of (14N2)cyanamide to (15N2)cyanamide in the injected sample was equal to the observed A 42/A 44 value in the range from 0.1 to 5. It was, therefore, possible to use the stable isotope dilution method to quantify the natural cyanamide content in samples; i.e., the natural cyanamide content was derived by subtracting the A 42/A 44 ratio of the internal standard from the A 42/A 44 ratio of sample spiked with internal standard, and then multiplying the resulting difference by the amount of added (15N2)cyanamide (SID-GC–MS method). This method successfully gave a reasonable value for the natural cyanamide content in hairy vetch, concurring with the value obtained by a conventional method in which cyanamide was derivatized to a photometrically active compound 4-cyanimido-1,2-naphthoquinone and analyzed with reversed-phase HPLC (CNQ-HPLC method). The determination range of cyanamide in the SID-GC–MS method was almost the same as that in the CNQ-HPLC method; however, the SID-GC–MS method was much simpler than the CNQ-HPLC method. [Copyright &y& Elsevier]

We investigated the influences of humic acid on the removal of Al tridecamer (Al13) from a hydroxyaluminum (HyA) solution at various humic acid/Al ratios. The Al species contained in the solution were analyzed by using a liquid-state 27Al-NMR and an atomic absorption spectrometer and fractionated into three Al species: (i) Al13, (ii) Al monomer and dimer (AlSYM), and (iii) other undefined species including aggregated/precipitated Al (AlNON). By the addition of humic acid to the HyA solution, the concentration of Al13 was rapidly decreased within 0.007 d (10 mm). The decrease in Al13 and the increase in AlNON were more pronounced at a higher humic acid/Al ratio. When the molar ratio of humic acid carboxylic groups to Al exceeded 0.8, Al-3 was undetected from solution within 0.007 d. The formation of Al13-humic acid complexes and the aggregation/precipitation of those complexes were a predominant mechanism in removing aqueous Al13 at the early stage of the reaction. Approximately 10 mol of carboxylic groups in humic acid were required to remove 1 mol of Al13 from the HyA solution. Aqueous AID had greater preference in precipitating with humic acid than AlSYM. After 5 to 570 d of aging, the concentration of Al13 and AlNON also decreased and increased, respectively, both in the presence and absence of humic acid. In conclusion, aqueous Al13 would not exist in soil solution under a high humic acid condition. [ABSTRACT FROM AUTHOR]

Spiraea thunbergii Sieb. was found to contain 1-O-cis-cinnamoyl-β-d-glucopyranose and 6-O-(4′-hydroxy-2′-methylene-butyroyl)-1-O-cis-cinnamoyl-β-d-glucopyranose as major plant growth inhibitory constituents along with related compounds of lower phytotoxicity including 6-O-(trans-cinnamoyl)-1-O-(4″-hydroxy-3″-methyl-furan-2″-one)-β-d-glucopyranose, 6-O-(4′-hydroxy-2′-methylene-butyroyl)-1-O-trans-cinnamoyl-β-d-glucopyranose, and 1-O-trans-cinnamoyl-β-d-glucopyranose. The former three compounds were cinnamoyl glucosides. [Copyright &y& Elsevier]

Presents a study which investigated aluminum speciation in aluminum-silica solutions and potassium chloride extracts of acidic soils. Methodology employed to differentiate chemical species of Al in soil solutions; Utilization of nuclear magnetic resonance (NMR) technique to conduct study; How NMR was applied; Findings of study.

Soil organic matter (SOM) is one of the largest carbon (C) reservoirs on Earth, and therefore its stability attracts a great deal of interest from the perspective of the global C cycle. This study examined the applicability of loss-on-ignition with a stepwise increase in temperature (SIT-LOI) of soil to evaluate the stability of SOM using soil samples having different organic matter (OM) and mineral contents and different mean residence times (MRTs) for SOM. The responses of SOM to the SIT-LOI varied depending on the samples but were all successfully approximated by a liner regression model as a function of the temperature of LOI. The slope value in the liner model that determines the residual potential of carbon during the SIT-LOI highly correlated with MRT of SOM, suggesting that this value reflects the overall stability of SOM over a range of soil properties. This hypothesis was consistent with the observation that Δ14C values of SOM decreased with increasing LOI temperature and thus, older, slower-cycling SOM was preferentially left in the soil samples by SIT-LOI. Additionally, the hypothesis was also supported by the significant correlations (p < 0.01) between the slope value and OM and mineral contents in the samples because these components are considered to regulate SOM stability. In addition to the regression analysis of the SIT-LOI data, changes in carbon to nitrogen (C/N) and carbon to hydrogen (C/H) ratios and stable carbon isotope signatures (δ13C) of the samples were investigated. The results suggest that the mineral association of SOM is an important factor characterizing the response of SOM to LOI. Hence, it was concluded that SIT-LOI is a simple and useful method for evaluating the stability of SOM under actual environmental conditions. • Loss-on-ignition (LOI) was used to evaluate soil organic matter (SOM) stability. • LOI data from 50 to 600 °C correlated with the mean residence time of SOM. • Soil mineral and organic matter contents correlated with LOI data. • LOI data can reflect the stability of SOM in actual environments. [ABSTRACT FROM AUTHOR]

In recent years, computer simulation has been increasingly used to predict changes in actual ecosystems. In these studies, snapshots of ecosystems at certain points in time were instantly constructed without considering their evolutionary histories. However, it may not be possible to correctly predict future events unless their evolutionary processes are considered. In this study, we developed a new ecosystem model for reproducing the evolutionary process on an oceanic island, targeting Nakoudojima Island of the Ogasawara Islands. This model successfully reproduced the primitive ecosystem (the entire island covered with forest) prior to the invasion of alien species. Also, by adding multiple alien species to this ecosystem, we were able to reproduce temporal changes in the ecosystem of Nakoudojima Island after invasion of alien species. Then, we performed simulations in which feral goats were eradicated, as had actually been done on the island; these suggested that after the eradication of feral goats, forests were unlikely to be restored. In the ecosystems in which forests were not restored, arboreous plants with a high growth rate colonized during the early stage of evolution. As arboreous plants with a high growth rate consume a large amount of nutrient in soil, creating an oligotrophic state. As a result, plants cannot grow, and animal species that rely on plants cannot maintain their biomass. Consequently, many animals and plants become extinct as they cannot endure disturbances by alien species, and the ecosystem loses its resilience. Therefore, even if feral goats are eradicated, forests are not restored. Thus, the founder effect from the distant past influences future ecosystem changes. Our findings show that it is useful to consider the evolutionary process of an ecosystem in predicting its future events. [ABSTRACT FROM AUTHOR]

Soil erosion after vegetation degradation induced by disturbance by feral goats, an invasive mammal, can lead to loss or accumulation of soil at a local scale and can alter soil chemical properties. This alteration of soil properties can in turn affect the establishment of plant species. We evaluated relationships among the extent of soil erosion, soil chemical properties, and the distribution of plant species in grassland ecosystems after goat eradication on Nakodo‐jima Island in the northwestern Pacific. In 105 1 × 1–m quadrats, changes were measured in the position of topsoil over 2 years. Surface soils were sampled for analysis of chemical properties, and plant species in the quadrat were recorded. Changes in the position of topsoil were related to the area of bare ground. Soil loss occurred at sites where areas of bare ground were extremely large. Significantly higher values of soil exchange acidity and smaller amounts of available phosphorus, total carbon, and total nitrogen were detected in soils at sites with large soil losses. Most of the 11 dominant plant species were absent from sites with large losses of soil. The presence of eight species was significantly negatively related to soil exchange acidity, and three species were significantly positively related to available phosphorus. Our results indicated that exposure of subsoils at the soil surface after vegetation degradation can increase soil loss, which can alter soil chemical properties, and this alteration can continue to limit the establishment of plant species, even long after goat eradication. [ABSTRACT FROM AUTHOR]

Abstract: At 12,900aBP, the eruption of the Laacher See volcano generated a new parent material for Holocene soil formation in parts of Western Germany. Weathering of these ashes commonly includes the formation of poorly crystalline minerals such as allophane, imogolite and ferrihydrite. Detection of these minerals in soil is difficult, yet an important task, because they may govern soil functions and processes, e.g., stabilisation of organic matter and nutrient availability. Therefore, we characterised three forested Andosols by a combination of wet-chemical and spectroscopic techniques including infrared and (27Al, 29Si) nuclear magnetic resonance (NMR) spectroscopy together with X-ray diffractometry. Deconvoluting the 29Si-NMR spectra revealed that 1.6 to 10.4% of total Si was present as allophanic compounds, which coincided with the amounts of oxalate-extractable Si. Since extraction methods are not completely selective, we observed a slight overestimation of allophanic Si estimated from oxalate extraction. Although the sites under study are located close to each other in similar relief positions and with similar vegetation, the combination of our results revealed varying amounts of loess in the parent materials and varying weathering intensity. High weathering intensities correlate with the amounts of allophane. [Copyright &y& Elsevier]

Questions What is the best way to identify plant indicators for monitoring the responses of semi-natural grassland communities to various management practices (i.e. burning, burning and mowing, burning and grazing)? Can a multi-trait plant functional group ( PFG) approach extract indicator species more effectively than a single-trait approach? Location Semi-natural and artificial grasslands in the northern and eastern parts of the somma of Mt. Aso, Kumamoto Prefecture, Japan. Methods We analysed a data set from 203 semi-natural and artificial grassland vegetation plots (each 1 m × 1 m), and compared species and functional compositions among the management types and between the northern and eastern locations using non-metric multidimensional scaling ( NMDS). Potential indicator species were extracted by indicator species analysis ( INSPAN) and compared with the results of single-trait and multi-trait PFG approaches, which classify plant species into groups based on individual or combinations of traits (growth form, life span, dispersal mode, flowering season and plant height). Results Only the multi-trait PFG approach successfully clustered the vegetation plots for each management type. Semi-natural burned-and-grazed grasslands in the eastern and northern regions were characterized by a specific PFG among 21 PFGs, whereas the same three PFGs characterized the burned-and-mowed semi-natural grassland of the two regions. The extracted PFGs represent combinations of vegetative, dispersal and reproductive traits (e.g. short, wind- and animal-dispersed species for grazed semi-natural grasslands; tall, summer-flowering forbs for mowed semi-natural grasslands). As compared to indicator species extracted by the multi-trait PFG approach, INSPAN extracted additional indicator species, but some of these were inappropriate. Conclusions We identified PFGs representing each management type and characterized species adaptations to different disturbance regimes, such as mowing and grazing. Among the species extracted by INSPAN, only those classified into the representative PFGs can serve as indicators for characterizing managed semi-natural grasslands. Our findings indicate that using a multi-trait PFG approach can provide reasonable plant indicators for monitoring grassland communities throughout the regions when combined with a species-based INSPAN approach. This proposed method would contribute to the conservation of plant biodiversity in threatened semi-natural grazed and mowed grasslands. [ABSTRACT FROM AUTHOR]

Physiological and biochemical studies on the leaf apoplast have been facilitated by the use of the infiltration–centrifugation technique to collect intercellular washing fluid (IWF). However, this technique has been difficult to implement in rice (Oryza sativa L.) for various reasons. We compared the collection efficiency of leaf IWF between two types of rice varieties (Indica and Japonica), as well as between rice and other species (spinach, snap bean and wheat). Although the extraction of IWF in most species took only 2–3 min, it took up to 35 min in rice. The difficulty in infiltration with rice was ascribed to the small stomatal aperture and hydrophobicity of the leaves. In this study, we have established an improved method for collecting IWF and determining the apoplastic air and water volumes in rice leaves. We have shortened the infiltration time to 8 min via the following improvements: (i) infiltration under outdoor shade in the daytime to prevent stomatal closure and a rise in temperature of the infiltration medium; (ii) soaking of leaves in a surfactant solution to decrease the leaf hydrophobicity; and (iii) continuous pressurization using a sealant injector to facilitate the infiltration. The rapid collection of IWF achieved using this technique will facilitate study of the leaf apoplast in rice. [ABSTRACT FROM AUTHOR]

Abstract: Dissolved organic matter (DOM) plays an important role in ecosystem processes such as nutrient release and utilization, mobilization and transport of metals, and carbon sequestration. We investigated the chemical properties of soils from the Bear Brook Watershed in Maine (BBWM) which is the site of a long-term paired-watershed experimental acidification study that includes both deciduous and coniferous stands. Multi-dimensional fluorescence spectroscopy combined with parallel factor analysis (PARAFAC) of the spectra, nuclear magnetic resonance spectroscopy, and size-exclusion chromatography, were used to characterize the DOM extracted from soils sampled from BBWM at four soil depth increments in 2003. Principal component analysis of the base cation, metal, and total C content of the mineral horizons indicated a strong negative relationship between pH and soil Al, Fe, P, and C. The close clustering of Al, Fe, P, and C loadings for the mineral soils suggests that organic matter is important for Al and Fe mobilization and that P solubility is influenced by the metal mobilization process. PARAFAC modeled the fluorescence spectra with three fluorescing components that were in the landscape regions typical of humic substances: (339 nm excitation/470 nm emission), (324 nm/418 nm), and (<240/465 nm) and the relative distributions of the three components were similar amongst the four treatments and four soil depth increments. The size exclusion chromatograms also revealed a high degree of similarity between all the extracted DOM. Our data suggests that litter quality as influenced by forest composition and ecosystem acidification exert a minor influence on the chemical composition of the water-soluble soil DOM fraction. [Copyright &y& Elsevier]

Lycoris radiata Herb., a common medicinal plant of Far East Asia, was examined for its potential use in paddy weed control. The preliminary screening in greenhouse conditions indicated growth inhibitory activities. The emergence, root and shoot growth, and root dry weight of the bioassay species were reduced when grown in soil mixed with the leaves of L. radiata. Aqueous extracts of the fresh leaves at various concentrations inhibited the root and shoot growth of all tested plant species. To identify the active components, L. radiata ethanolic extract was subjected to bioassay-guided fractionation, purification, and spectroscopic analysis. This process led to the isolation of lycorine as a potential allelochemical. The concentration of lycorine in the dry leaves of L. radiata is estimated to be 0.08%. It is possible that lycorine is exuded from the roots or leaches from the living or decomposing leaves, along with other numerous inhibitors, and inhibits the growth of neighboring or successional plants. These results suggest that L. radiata has the potential to inhibit plant growth and lycorine acts as one of the most important plant growth inhibitors. This plant can be grown as a ground cover plant and its dead leaves could be applied as cover mulch. [ABSTRACT FROM AUTHOR]

Plant growth inhibitory alkaloids were isolated from the extract of mesquite [Prosopis juliflora (Sw.) DC.] leaves. Their chemical structures were established by ESI-MS, 1H and 13C NMR spectra analysis. The I50 value (concentration required for 50% inhibition of control) for root growth of cress (Lepidium sativum L.) seedlings was 400 μM for 3⁗-oxo-juliprosopine, 500 μM for secojuliprosopinal, and 100 μM for a (1:1) mixture of 3-oxo-juliprosine and 3′-oxo-juliprosine, respectively. On the other hand, the minimum concentration exhibiting inhibitory effect on shoot growth of cress seedlings was 10 μM for 3⁗-oxo-juliprosopine, 100 μM for secojuliprosopinal, and 1 μM for a (1:1) mixture of 3-oxo-juliprosine and 3′-oxo-juliprosine, respectively. Among these compounds, a (1:1) mixture of 3-oxo-juliprosine and 3′-oxo-juliprosine exhibited the strongest inhibitory effect on the growth of cress seedlings. [Copyright &y& Elsevier]

The absolute configurations of 2-methoxy-2-(1-naphthyl)propionic acid and 2-methoxy-2-(2-naphthyl)propionic acid were reconfirmed by NMR analyses of phenylglycine methyl ester (PGME) derivatives. Their absolute configurations determined by the PGME method are consistent with those obtained by the 1H NMR anisotropy method and X-ray crystallography. [Copyright &y& Elsevier]

Effective conservation of global species diversity requires a clear understanding of spatial scales that support overall diversity across broad scales. Abandonment of semi-natural grasslands has increased their fragmentation and decreased their areal extent. We quantified diversity patterns of plant communities in Japan across hierarchical scales to facilitate the development of an effective nationwide strategy for conserving species diversity in remnant semi-natural grasslands. We applied additive partitioning of plant species diversity, using a nested hierarchical design at three spatial scales (quadrat, grassland, and western and eastern regions of Japan) for three groups of plant species (all species, grassland species and national Red Listed species). We consistently found lower proportions of among-quadrats diversity, and higher proportions of among-grasslands diversity and between-regions diversity in the overall diversity of the entire species complement than would be expected by chance. The high contribution of among-grasslands diversity to overall diversity suggests that each grassland had a unique species content. The second-ranking contributor to overall diversity differed between grassland species and Red Listed species: the second-ranking contributor for grassland species was diversity at the among-quadrats scale but the second-ranking contributor for all species and for Red Listed species was diversity at the between-regions scale. Thus, effective conservation of diversity of the entire species complement in remnant semi-natural grasslands requires preservation of beta diversity in individual grasslands. Our findings highlight the importance of strengthening local preservation and restoration activities within each grassland, and of nationwide strategies for conserving Red Listed species in remnant semi-natural grassland communities. [ABSTRACT FROM AUTHOR]

Tricholoma matsutake, a basidiomycete, forms ectomycorrhizas withPinus densifloraas the host tree. Its fruiting body, “matsutake” in Japanese, is an edible and highly prized mushroom, and it grows in a circle called a fairy ring. Beneath the fairy ring ofT. matsutake, a whitish mycelium-soil aggregated zone, called “shiro” in Japanese, develops. The front of the shiro, an active mycorrhizal zone, functions to gather nutrients from the soil and roots to nourish the fairy ring. Bacteria and sporulating fungi decrease from the shiro front, whereas they increase inside and outside the shiro front. Ohara demonstrated that the shiro front exhibited antimicrobial activity, but the antimicrobial substance has remained unidentified for 50 years. We have identified the antimicrobial substance as the (oxalato)aluminate complex, known as a reaction product of oxalic acid and aluminum phosphate to release soluble phosphorus. The complex protects the shiro from micro-organisms, and contributes to its development. “Antimicrobial activity of the matsutake shiro” for left figure.“The antimicrobial substance, the (oxalato)aluminate complex, from the matsutake shiro” for right figure. [ABSTRACT FROM PUBLISHER]

Soil water repellency (SWR) of soils is a property with significant consequences for agricultural water management, water infiltration, contaminant transport, and for soil erosion. It is caused by the presence of hydrophobic agents on mineral grain surfaces. Soils were samples in different depths at three forest sites in Japan and three pasture sites in New Zealand, covering soil organic carbon (SOC) contents between 1 and 26%. The SWR was measured over a range of water contents by three common methods; the water drop penetration time (WDPT) test, the molarity of an ethanol droplet (MED) method, and the sessile drop method (SDM). The aim to (i) compare the methods, (ii) characterize the soil-water repellency characteristic curves (SWRCC) being SWR as a function of the volumetric soil-water content ( θ ) or matric potential ( ψ ), and (iii) find relationships between SWRCC parameters and SOC content. The WDPT, MED, and SDM generally agreed well in predicting the θ range where SWR occurred, and there was close agreement between SWR results determined by average MED and SDM at similar θ . Generally, SWR was only found within the top 20 cm of the soil profiles. Six SWR parameters were introduced: (i) the area under the curve ( S WR ( θ ) ); (ii) θ at the maximum SWR ( θ WR-max ), (iii) θ where SWR ceased ( θ non-WR ), (iv) the maximum SWR ( CA i -max ), (v) pF at the maximum SWR ( pF WR-max ) and (vi) pF where SWR ceased ( pF non-WR ). The relationship between the first three parameters and SOC content were best described with Langmuir type equations (r 2 of 0.5–0.7), while the other three parameters changed linearly with SOC contents. [ABSTRACT FROM AUTHOR]

Organic matter (OM) bound to soil mineral particles (higher-density particles) tends to be more stabilized, enriched in 13 C and 15 N, and has a lower C:N ratio. Yet how these variations in OM chemistry are linked to the nature of organo-mineral assemblage remains poorly understood, especially in allophanic soils where high amounts of OM are stabilized by interactions with reactive inorganic phases such as short-range-order (SRO) minerals. We thus assessed the extent to which the degree of aggregation and its disruption during fractionation control the distribution and chemistry of the soil organo-mineral particles across six density fractions using a volcanic soil (allophanic Andisol) based on selective dissolution, microscopy (SEM), solid-state 13 C NMR spectroscopy and δ 13 C and δ 15 N analyses. Intermediate-density fractions (2.0–2.5 g cm − 3 ) accounted for 63–86% of organic C and N, 73–93% of pyrophosphate-extractable iron and aluminum (Fep, Alp), and 78–95% of oxalate-extractable metals (Feo, Alo) in the bulk soil sample. While air-drying pretreatment had little effect, sonication during fractionation led to (i) fragmentation of both plant detritus and some of the aggregates of 30–100 mm sizes, (ii) release of occluded low-density fraction (< 1.6 g cm − 3 ) which largely originated from the aggregates of 1.6–2.0 g cm − 3 density range, and (iii) redistribution of organo-mineral particles (15–16% of total OM and 7–19% of the extractable metals) within the intermediate density fractions. Positive correlation of Alp with C:N ratio and negative correlation of Alp with δ 15 N among the fractions suggest preferential binding of Alp phase (e.g., organo-Al complexes) to decaying plant detritus. Positive correlation of Alo and Feo with δ 15 N, together with theoretical density calculations of idealistic organo-mineral association modes, suggests that 15 N enrichment may be coupled with OM binding to SRO minerals and with the formation of physically-stable aggregates of micron/submicron sizes in accord with our conceptual model (Asano and Wagai, 2014). The general pattern of 13 C and 15 N enrichment and C:N decline with increasing particle density remained largely unchanged despite the sonication effects detected, indicating that sonication-resistant organo-mineral assemblages largely control the observed patterns. The similarity in the density-dependent changes of OM chemistry between the studied Andisol and the soils with crystalline clay and metal oxide mineralogies in previous studies strongly suggests a common biogeochemical control which deserves further investigation. [ABSTRACT FROM AUTHOR]

This study examined the recovery, via biotic and abiotic pathways, of a grassland ecosystem after eradication of introduced exotic goats. We used path analyses to evaluate the relative strength of relationships among aboveground biomass, soil chemical properties (carbon, nitrogen, and phosphorus content; soil acidity), presence of nesting seabirds after goat eradication, extent of vegetation degraded by goats before their eradication, plant species composition after removal of goats, and topography. Models including the same variables with different paths were constructed using the Bayesian estimation method, and the best-fit models were constructed by comparing deviance information criterion values. Results of the path analyses demonstrated that vegetation degradation and soil erosion prior to goat eradication increased soil exchangeable acidity, which resulted in limitation of aboveground biomass. Seabird nesting after goat eradication increased the quantity of soil nutrients, possibly through inputs of feces, eggshells, and dead chicks or adults. The increase in nutrients was affected indirectly, via seabird nesting, by topography and vegetation type after goat eradication. The direct and indirect relationships demonstrated by our results suggest the existence of complex interrelationships during recovery of ecosystem function after eradication of exotic mammals. [ABSTRACT FROM AUTHOR]

To establish a rapid high-throughput evaluation system for the enhanced plant growth-inhibitory activity caused by modifications of cis-cinnamic acid's (cis-CA's) chemical structure, a DNA microarray assay was used to analyze the changes in early gene responses of Arabidopsis thaliana seedlings. After a 6-hr exposure to (Z)-3-(3-iodophenyl)acrylic acid, we observed an upregulation in three classes of early auxin-responsive genes, which was similar to the transcriptional response to indole-3-acetic acid (IAA), together with an upregulation of the genes related to environmental stress and toxin detoxification responses. Gene responses to 2-(3,4-dihydronaphthalen-1-yl)acetic acid were similar to those to IAA. In contrast, fewer genes were upregulated in response to its double-bond isomer, (Z)-2-[3,4-dihydronaphthalen-1(2H)-ylidene]acetic acid, than to cis-CA. DNA microarray data suggest that the structurally different cis-CA analogues trigger diverse gene responses. [ABSTRACT FROM AUTHOR]

Highlights: [•] Conformationally constrained cis-cinnamic acid analogues were designed, in which the aromatic ring and the cis-olefin are connected by a carbon bridge. [•] Their inhibitory activities on elongation of lettuce roots was evaluated with inhibitory activities of five- and six-membered bridged compounds being enhanced. [•] The cis-analogue having a five-membered ring exhibited bioactivity ten times higher than cis-cinnamic acid. [Copyright &y& Elsevier]

Highlights: [•] cis-Cinnamic acid analogues was synthesized having substituents on the aromatic ring, and their inhibitory activities on the elongation of lettuce roots were evaluated. [•] Para- and ortho-substitution decreased potency. [•] meta-Substituted cis-cinnamic acid analogues were more likely to be potent. [•] m-Iodo, m-methoxy and m-trifluoromethyl substituents induced higher potency. [Copyright &y& Elsevier]

Highlights: [•] The citrate content in the roots was increased with Al treatments. [•] The activities of aconitase and NADP+-ICDH were decreased with Al treatments. [•] The activity of citrate synthase was not affected by Al. [•] Al–citrate complexes were a major chemical form in the cell sap of root tips. [Copyright &y& Elsevier]

Temperature sensitivity of soil organic matter ( SOM) decomposition may have a significant impact on global warming. Enzyme-kinetic hypothesis suggests that decomposition of low-quality substrate (recalcitrant molecular structure) requires higher activation energy and thus has greater temperature sensitivity than that of high-quality, labile substrate. Supporting evidence, however, relies largely on indirect indices of substrate quality. Furthermore, the enzyme-substrate reactions that drive decomposition may be regulated by microbial physiology and/or constrained by protective effects of soil mineral matrix. We thus tested the kinetic hypothesis by directly assessing the carbon molecular structure of low-density fraction ( LF) which represents readily accessible, mineral-free SOM pool. Using five mineral soil samples of contrasting SOM concentrations, we conducted 30-days incubations (15, 25, and 35 °C) to measure microbial respiration and quantified easily soluble C as well as microbial biomass C pools before and after the incubations. Carbon structure of LFs (<1.6 and 1.6-1.8 g cm−3) and bulk soil was measured by solid-state 13C- NMR. Decomposition Q10 was significantly correlated with the abundance of aromatic plus alkyl-C relative to O-alkyl-C groups in LFs but not in bulk soil fraction or with the indirect C quality indices based on microbial respiration or biomass. The warming did not significantly change the concentration of biomass C or the three types of soluble C despite two- to three-fold increase in respiration. Thus, enhanced microbial maintenance respiration (reduced C-use efficiency) especially in the soils rich in recalcitrant LF might lead to the apparent equilibrium between SOM solubilization and microbial C uptake. Our results showed physical fractionation coupled with direct assessment of molecular structure as an effective approach and supported the enzyme-kinetic interpretation of widely observed C quality-temperature relationship for short-term decomposition. Factors controlling long-term decomposition Q10 are more complex due to protective effect of mineral matrix and thus remain as a central question. [ABSTRACT FROM AUTHOR]

Abstract: 1-O-cis-cinnamoyl-β-d-glucopyranose is one of the most potent allelochemicals isolated from Spiraea thunbergii Sieb. It is suggested that it derives its strong inhibitory activity from cis-cinnamic acid, which is crucial for phytotoxicity. It was synthesized to confirm its structure and bioactivity, and also a series of cis-cinnamic acid analogues were prepared to elucidate the key features of cis-cinnamic acid for lettuce root growth inhibition. The cis-cyclopropyl analogue showed potent inhibitory activity while the saturated and alkyne analogues proved to be inactive, demonstrating the importance of the cis-double bond. Moreover, the aromatic ring could not be replaced with a saturated ring. However, the 1,3-dienylcyclohexene analogue showed strong activity. These results suggest that the geometry of the C–C double bond between the carboxyl group and the aromatic ring is essential for potent inhibitory activity. In addition, using several light sources, the photostability of the cinnamic acid derivatives and the role of the C–C double bond were also investigated. [Copyright &y& Elsevier]

The mycotoxin deoxynivalenol (DON) causes serious problems worldwide in the production of crops such as wheat and barley because of its toxicity toward humans and livestock. A bacterial culture capable of degrading DON was obtained from soil samples collected in wheat fields using an enrichment culture procedure. The isolated bacterium, designated strain WSN05-2, completely removed 1,000 μg/mL of DON from the culture medium after incubation for 10 days. On the basis of phylogenetic studies, WSN05-2 was classified as a bacterium belonging to the genus Nocardioides. WSN05-2 showed significant growth in culture medium with DON as the sole carbon source. High-performance liquid chromatography analysis indicated the presence of a major initial metabolite of DON in the culture supernatant. The metabolite was identified as 3- epi-deoxynivalenol (3- epi-DON) by mass spectrometry and H and C nuclear magnetic resonance analysis. The amount of DON on wheat grain was reduced by about 90% at 7 days after inoculation with WSN05-2. This is the first report of a Nocardioides sp. strain able to degrade DON and of the yet unknown 3- epi-DON as an intermediate in the degradation of DON by a microorganism. [ABSTRACT FROM AUTHOR]

Abstract: Ogasawara Islands are important ecosystems sustaining many indigenous spices. To clarify the indigenous soil environments of Ogasawara Islands, we studied the chemistry of the soils. Many surface soils were low in bio-available P (0 to 0.55g P2O5 kg−1, average: 0.04g P2O5 kg−1 as Bray II P, n =22), but several soils were found to contain extremely large amounts of bio-available P (1.36 to 6.98g P2O5 kg−1, average: 2.93g P2O5 kg−1, n =5). From soil profile analyses, the authors concluded that the extremely large amount of bio-available P could not be explained by the effects of parent materials with high P contents nor the effect of fertilizations by human activity, but the effects of natural seabird activities in the past could be the cause. The soil profiles with large amounts of bio-available P indicate deep migration of soil materials from A horizons, which could be a result of intensive mixing of upper horizons by seabird activities. The intensive mixing was supported by the low mechanical impedance of the horizons for the P-accumulating soils (8.17±2.54kgcm−2, n =8) than those for the non-P-accumulating soils (17.46±3.52kgcm−2, n =36). It is likely that in the past seabirds, such as shearwaters, made burrows in the soils for nesting and propagating and inadvertently transported a large amount of P from the sea to the soils, resulting in the extremely large amounts of bio-available P in the present soils. [ABSTRACT FROM AUTHOR]

The methanol extract of Bletilla striata, an ornamental orchid in eastern Asia, exhibited plant growth-inhibitory activity. It was purified by continuous chromatography, based on the inhibitory activity against the growth of lettuce seedlings, resulting in two glycosidic compounds, militarine and dactylorhin A. The EC50 values of militarine and dactylorhin A against the radicle elongation of the lettuce seedlings were 0.28 and 0.88 mmol L−1, respectively. The amount of militarine and dactylorhin A in the methanol extract of the aerial part of B. striata was calculated to be 5.6 and 7.5 mg g−1 fresh weight, respectively. The inhibitory activity of militarine and its content in the methanol extract revealed that the plant growth-inhibitory activity of the extract of B. striata was mainly related to militarine. The inhibitory activity of militarine against the growth of Italian ryegrass and timothy were of the same level as that of lettuce. [ABSTRACT FROM AUTHOR]

Abstract: To quantitatively clarify the organic carbon accumulation processes on the forest floor during an early stage of humification (3 years), solid-state 13C cross polarization magic angle spinning nuclear magnetic resonance (CPMAS NMR) signals were monitored for phased–humified beech and oak litters and soil surface horizons in the northern Kanto District, Japan. The mass loss rate of the carbon components during the humification for both litters was in the following order: O-alkyl > aromatic > aliphatic > carbonyl carbons. This result indicates that the labile O-alkyl carbons, probably dominated by holocellulose were selectively degraded compared to the other components. 44% of O-alkyl carbon mass for beech and 38% for oak lost throughout 3 years of incubation. Inversely, the mass of aliphatic carbons, which is mainly composed of saturated hydrocarbons, decreased quite slowly from 20 to 10% with humification, probably because a large proportion of the aliphatic carbons are secondary products of microorganisms. The aromatic carbon mass, which would be derived from lignin/tannin and their metabolites, also decreased gradually from 17 to 6% over 3 years. While, the carbonyl carbon mass was quite stable at around 2% throughout the incubation period, probably because the hydrolysis reactions of organic carbon would contribute to the formation of the carbonyl carbons. According to an exponential model, the total carbon stocks on the forest floor converged at 4.2 Mg C ha−1 for the first few years at the studying site. The carbon compositions converged to intermediate levels between those of the F and A 1 horizons. The simulation in the present study is able to represent the carbon accumulation process on the forest floor including a part of the mineral. [Copyright &y& Elsevier]

The article offers information on the adaptive aluminum resistance in Rhodotorula glutinis through mitochondrial regulation. It examines the microbial acclimation to increasing aluminum stress, as well as the mechanisms responsible for adaptive aluminum resistance. Wild-type and aluminum resistant cells were compared to determine the mechanism underlying the acquired aluminum resistance of Rhodotorula glutinis IFO1125. A greater number of mitochondria was found in resistant cells. It is revealed that increased number of mitochondria and increased mitochondrial DNA content is directly related to increased aluminum resistance.

Abstract: Cyanamide (NH2CN) has recently been proven to be a natural product, although it has been synthesized for over 100 years for agricultural and industrial purposes. The distribution of natural cyanamide appears to be limited, as indicated by our previous investigation of 101 weed species. In the present study, to investigate the distribution of natural cyanamide in Vicia species, we monitored the cyanamide contents in V. villosa subsp. varia, V. cracca, and V. amoena during their pre-flowering and flowering seasons. It was confirmed that V. cracca was superior to V. villosa subsp. varia in accumulating natural cyanamide, and that V. amoena was unable to biosynthesize this compound under laboratory condition examined. The localization of cyanamide in the leaves of V. villosa subsp. varia seedlings was also clarified. In a screening study to find cyanamide-biosynthesizing plants, only Robinia pseudo-acacia was found to contain cyanamide among 452 species of higher plants. We have investigated 553 species to date, but have so far found the ability to biosynthesize cyanamide in only three species, V. villosa subsp. varia, V. cracca and R. pseudo-acacia. [Copyright &y& Elsevier]

Abstract: To determine the mechanism of aluminum (Al) detoxification in the roots of tea plants (Camellia sinensis (L.) Kuntze), the amounts of Al and Al-chelating compounds (fluoride (F), organic acids and catechins) were measured and the chemical forms of Al in root cell extracts were identified by the application of 27Al-nuclear magnetic resonance (NMR) spectroscopy. Tea plants were cultivated in nutrient solutions containing 0, 4, 1.0 and 4.0mM of Al at pH 4.2 for approximately 10 weeks. The levels of soluble Al, water-soluble oxalate and citrate, but not F, malate or catechins in young roots increased with an increase in the concentration of Al in the treatment solution. The 27Al NMR spectra of root tips and cell sap extracted from root tips that had been treated with Al were almost identical and had four signals, with two (11 and 16ppm) apparently corresponding to the known chemical shifts of Al–oxalate complexes. In the spectra of cell sap, the resonances at 11 and 16ppm increased with an increase in the Al contents. These results suggest that the levels of Al–oxalate complexes increased in response to an increase in the Al level, implying that oxalate is a key Al-chelating compound in the mechanism of Al detoxification in the tea root. [Copyright &y& Elsevier]

The production of quorum-sensing-related signal molecules (QSRMs) among culturable bacteria comprising the community on wheat heads was investigated. The taxonomic position of 186 bacterial isolates obtained from ten heads was inferred based on 16S rRNA gene sequences, and their QSRM production was determined using two bioreporter strains of N-acylhomoserine lactones. Approximately 33% of isolates produced QSRMs, though the proportion of QSRM-producing isolates on a wheat head was significantly negatively correlated with population size. Most of the producing isolates were Pantoea species, most commonly Pantoea ananatis. Furthermore, the proportion of Pantoea ananatis that produced QSRMs was significantly negatively correlated with the number of bacterial genera (community richness) on each head. Finally, community richness was positively correlated with population size. Qualitative analysis using thin-layer-chromatography revealed that the QSRMs of Pantoea isolates were composed of at least two compounds. This is the first report indicating that Pantoea ananatis isolates inhabiting wheat heads are capable of producing QSRMs. QSRM production by Pantoea spp. may contribute to the predominance of this genus on wheat heads, particularly at relatively low population densities and community diversity. [ABSTRACT FROM AUTHOR]

Focuses on sex pheromone and related compounds in the Ishigaki and Okinawa strains of the tussock moth Orgyia postica (Walker). Discovery of two distinct electroantennographycally active components, A and B, and a weakly active component C in a solvent extract from virgin females of the Ishigaki strain of the tussock moth; Finding of components A, B, and C in the extract of the females at 4.0, 0.5, and 4.0 ng/female respectively; Confirmation that the attractant pheromone of O. postica of the Ishigaki strain is also (11S,12S)-1; Discussion of the attractiveness of the components to the males on both Japanese islands in the context of the activity and possible evolution of pheromonal polymorphism in the species.

In order to elucidate the allelopathic effect of leaf litter leachates under laboratory conditions, a modified ‘sandwich method’, which places leaves between two layers of agar, was used. Fifty mg of leaves was used per 10 cm2 cell. Agar concentrations at 0.5–1.0% were the best for gel support in determining radicle and hypocotyl elongation of lettuce. The optimum incubation time for bioassay was three days after imbibition onset. Among 20 typical tree species in Asia, Cymbopogon citratus and Derris scandens showed the strongest inhibitory activity determined by the sandwich method, followed by Piper betle, Tamarindus indica, and Gliricidia sepium. This bioassay seems to be a reliable method for screening allelopathic activity from leaf litter leachates. [ABSTRACT FROM AUTHOR]