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Soil phosphorus (P) is a vital nutrient that controls wetland productivity and ecological functions. However, the effects of soil P forms on P availability during wetland degradation are relatively unknown. We selected differently degraded marshes, including non‐degraded marsh (NDM), lightly degraded marsh (LDM), moderately degraded marsh (MDM), and heavily degraded marsh (HDM), to research the changes in soil P forms by sequential chemical extraction and its regulation on P availability in the Zoige Plateau, China. The results showed that compared with the 0–30 cm soil layers of NDM, the main changes in total P concentration were a significant increase of 31.6%–44.2% in LDM and MDM, and the available P concentration increased by 28.7%–76.2% in LDM and MDM but decreased by 4.0%–47.5% in HDM with a lower P activation coefficient. Marsh degradation increased the concentration of soil dicalcium phosphates, P occluded in iron hydroxides, and organic P from the entire profile by 46.7%–137.7%, 31.7%–49.3%, and 78.1%–82.1%, respectively, while it decreased that of iron oxide surface adsorbed P and apatite P by 17.2%–32.2% and 15.3%–27.8%, respectively. Soil available P was mainly related to organic P and P non‐occluded in iron oxide minerals, which might also be a non‐negligible direct source of available P. The transformation from apatite P to organic P was an important regulatory mechanism of P availability in soils during marsh degradation. This study revealed the transformation trajectory of soil P forms owing to soil desiccation accompanied by plant community changes and overgrazing during alpine marsh degradation, and the risk of P limitation in HDMs with low soil available P. For degraded marsh restoration, some measures for improving P availability should be implemented in the future, such as grazing exclusion and the application of organic fertilizer. [ABSTRACT FROM AUTHOR]

Herbivore‐induced plant volatiles (HIPVs) are critical compounds that directly or indirectly regulate the tritrophic interactions among herbivores, natural enemies and plants. The synthesis and release of HIPVs are regulated by many biotic and abiotic factors. However, the mechanism by which multiple factors synergistically affect HIPVs release remains unclear. Tea plant (Camellia sinensis) is the object of this study because of its rich and varied volatile metabolites. In this study, benzyl nitrile was released from herbivore‐attacked tea plants more in the daytime than at night, which was consistent with the feeding behaviour of tea geometrid (Ectropis grisescens Warren) larvae. The Y‐tube olfactometer assay and insect resistance analysis revealed that benzyl nitrile can repel tea geometrid larvae and inhibit their growth. On the basis of enzyme activities in transiently transformed Nicotiana benthamiana plants, CsCYP79 was identified as a crucial regulator in the benzyl nitrile biosynthetic pathway. Light signalling‐related transcription factor CsPIF1‐like and the jasmonic acid (JA) signalling‐related transcription factor CsMYC2 serve as the activator of CsCYP79 under light and damage conditions. Our study revealed that light (abiotic factor) and herbivore‐induced damage (biotic stress) synergistically regulate the synthesis and release of benzyl nitrile to protect plants from diurnal herbivorous tea geometrid larvae. Summary statement: Tea geometrid‐induced volatile benzyl nitrile (BN) emission has a diurnal pattern, which is consistent with the feeding of tea geometrids. Light and damage induce the emission of BN and the CsCYP79 expression which is promote by the CsMYC2 and CsPIFs‐like. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is an important environmental heavy metal and one of the main soil pollutants in southwest China and even the Yangtze River Basin because of its toxicity to plants and humans. To clarify the potential of Euryops pectinatus L. and Gardenia jasminoides J. and the mechanism they use to remediate Cd-contaminated soil, a soil pot experiment with 0, 5, 10, 20, and 40 mg kg−1 of Cd was used to investigate the accumulation characteristics, subcellular distribution, chemical forms, and the antioxidative defense systems of the two ornamental plants. When the concentration of Cd was below 40 mg kg−1, it promoted the growth of E. pectinatus shoots, and the tolerance index (TI) was >1. However, 20–40 mg kg−1 Cd significantly inhibited the growth of G. jasminoides, and the TI was <1. The shoots of both varieties accumulated more Cd than the roots, and the E. pectinatus shoots accumulated more Cd (1.45 mg plant−1) than those of G. jasminoides (0.71 mg plant−1). The Cd in E. pectinatus and G. jasminoides was primarily distributed in the soluble fraction (52.83–68.97%) and cell walls (44.62–54.98%), respectively. Higher proportions of Cd bound to NaCl and acetic acid (HAc) in E. pectinatus (55.32–73.44%) than in G. jasminoides (42.94–61.58%), while the inorganic and water-soluble proportions of Cd bound in the opposite manner. E. pectinatus maintained high activities of antioxidant enzymes under Cd treatments, and its levels of malondialdehyde (MDA) and relative electrical conductivity (REC) were comparable to those of the control. Nonetheless, G. jasminoides had low levels of activity of antioxidant enzymes, but its levels of MDA and REC were significantly higher than those of the control under the 20–40 mg kg−1 Cd treatment. Therefore, both types of plants have a strong ability to tolerate and accumulate Cd, which makes them suitable for the remediation of Cd-polluted soil. However, E. pectinatus is more effective at remediating Cd and tolerant to it than G. jasminoides. These plants utilize different mechanisms to detoxify Cd. [ABSTRACT FROM AUTHOR]

In this paper, hyperaccumulator straw (Solanum nigrum L., Amaranthus chinense L., and Siegesbeckia orientalis L.) and phosphate rock powder were selected as materials, a pot experiment was used to study the effects of three compounding modifiers on the growth, nutritional quality and cadmium (Cd) content of Chinese cabbage. The results showed that: (1) The combination of Siegesbeckia orientalis + phosphate rock powder can significantly promote the growth of Chinese cabbage, while Solanum nigrum + phosphate rock powder and Amaranthus chinense + phosphate rock powder have no effect on the growth of Chinese cabbage. (2) The combination of Solanum nigrum and phosphate rock powder increased the content of soluble sugar, soluble protein and VC in shoots of Chinese cabbage by 64.33%, 16.27% and 2.2%, respectively, and the nitrite content decreased by 34.58%, which improved the quality of Chinese cabbage. (3) Different compounding modifiers can significantly reduce the Cd content in shoots of Chinese cabbage, and the reduction of Solanum nigrum + phosphate rock powder is the largest, reaching 61.29%. In conclusion, all three modifiers can improve the nutritional quality and reduce the Cd content in the shoots of Chinese cabbage, and Solanum nigrum + phosphate rock powder has the best effect.

Soil culture experiments were carried out to study the effects of the mixture of cadmium (Cd) hyperaccumulator straw (Solanum nigrum L., Amaranthus chinense L., and Siegesbeckia orientalis L.) and phosphate rock on soil pH, available Cd content and soil nutrients in Cd polluted soil. The results showed that: (1) The soil pH was increased to a certain extent by three kinds of compound materials. (2) The contents of available potassium (AK) and available phosphorus (AP) in soil were increased to a certain extent by the three compounding materials, but there was no significant effect on total nitrogen (TN). And 2% phosphate rock powder and 1% Amaranthus chinense L. had the greatest increase in AP, reaching 49.28%, and 2% phosphate rock powder and 1% Siegesbeckia orientalis L. had the greatest increase in AK, reaching 136.23%. (3) The available Cd content in soil was reduced by three kinds of compound materials. The decrease of available Cd was the greatest in 2% phosphate rock powder and 1% Solanum nigrum L. straw mixed, which was 12.71%. In summary, the combination of Cd hyperaccumulator straw and phosphate rock powder can effectively passivate Cd in soil and improve soil nutrient content, and 2% phosphate rock powder and 1% Solanum nigrum L. straw are the best.

Soil culture experiments were carried out to study the effects of the mixture of Amaranthus chinense L. straw and phosphate rock on soil pH, available phosphorus (AP), available potassium (AK) and DTPA-Cd content in Cd polluted soil. The results showed that: (1) 2% phosphate rock powder combined with 1%, 2%, 3% of Amaranthus chinense L. straw can significantly increase soil pH, AP and AK content. Compared with CK, pH was increased by 0.42~0.56, 0.53~0.70 and 0.47~0.73 units, respectively, and AP was increased by 19.03%~32.62%, 14.91%~43.63% and 18.88%~58.01%, respectively, and AK was increased by 201.46%~234.66%, 210.5%~266.56% and 184.07%~224.98%, respectively. (2) The DTPA-Cd content in soil decreased significantly after adding three different ratios of compound materials, which were 1.75%~9.01%, 2.86%~10.02% and 0.98%~8.7% lower than CK, respectively. In summary, the mixture of 1% Amaranthus chinense L. straw and 2% phosphate rock powder had the best passivation effect on Cd.

Assessing soil quality (SQ) of cropland is fundamental for food security and sustainable land management. However, there is limited information regarding SQ assessment on a national scale, which is vital to answer important SQ‐related questions in quantitative terms on that scale. Here, the SQ of cropland in China was assessed by constructing a minimum data set (MDS) from 23 soil physicochemical properties based on principal component analysis. The interaction roles and relative contributions of climate and topography on SQ was evaluated by a structural equation model. The MDS comprised eight indicators: proportion of silt, bulk density, total phosphorus, total potassium, available nitrogen, exchangeable calcium, chlorite, and vermiculite. The soil quality index (SQI) varied from 0.245 to 0.705 and showed a clear pattern of decreasing quality from the north to the south of the country. Of the total cropland area in China, the largest share (27.91%) was of soils of high quality, followed by those of moderate quality (24.63%), low quality (20.37%), very high quality (14.18%), and very low quality (12.91%). The north and the south differed significantly in terms of total potassium, exchangeable calcium, chlorite, and vermiculite, which are the four most important indicators of SQ. Climate and elevation explained about 2.2%–30.1% of the variation in SQ on the national and regional scales. These findings suggest that croplands in southern China will benefit from potassium and calcium fertilizers, which will contribute to enhance food security and promote sustainable land management in China. [ABSTRACT FROM AUTHOR]

Some members of the CYP51G subfamily has been shown to be obtusifoliol 14α‐demethylase, key enzyme of the sterol and brassinosteroid (BR) biosynthesis, which mediate plant development and response to stresses. However, little is known about the functions of CYP51H subfamily in rice. Here, OsCYP51H3, an ortholog of rice OsCYP51G1 was identified. Compared with wild type, the mutants oscyp51H3 and OsCYP51H3‐RNAi showed dwarf phenotype, late flowering, erected leaves, lower seed‐setting rate, and smaller and shorter seeds. In contrast, the phenotypic changes of OsCYP51H3‐OE plants are not obvious. Metabolomic analysis of oscyp51H3 mutant indicated that OsCYP51H3 may also encode an obtusifoliol 14α‐demethylase involved in phytosterol and BR biosynthesis, but possibly not that of triterpenes. The RNA‐seq results showed that OsCYP51H3 may affect the expression of a lot of genes related to rice development. These findings showed that OsCYP51H3 codes for a putative obtusifoliol 14α‐demethylase involved in phytosterol and BR biosynthesis, and mediates rice development. [ABSTRACT FROM AUTHOR]

Urbanization has progressively intensified over the past few decades, transforming the structure and function of urban ecosystems and influencing the concentrations and spatial distributions of phosphorus (P) in the soil. This study collected 177 surface soil samples (to a depth of 20 cm) to understand the dynamics of soil P along a gradient of urbanization from a densely urbanized central city to less human-affected suburbs to a new exurban satellite in Chengdu, China. The results showed that concentrations of soil total P (TP) and its fractions (except Water-Po, NaOH-Pi, and Residual-P) in the central city and exurban satellite were significantly higher than in suburban areas ( p  < 0.05). Meanwhile, the concentrations of soil TP and its fractions (except Residual-P) significantly decreased with the increase in distance from the urban center ( p  < 0.05). These concentrations were significantly positively correlated with the densities of built-up areas and roads, and showed significant differences among different green space types. The results of generalized linear models indicated that the most decisive factors contributing to TP accumulation were the distance from urban center and green space type. Generally, green space type and density of built-up area were likely to be more crucial determinants governing soil inorganic P fractions compared with other factors, whereas the key factors affecting soil organic P fractions were varied. To conclude, urbanization is likely to lead to the accumulation of P and, thus, controlling the expansion of built-up areas and road areas is necessary to alleviate soil P accumulation in urban systems. [ABSTRACT FROM AUTHOR]

Soil washing with natural chelators to remediate metal-contaminated soils has been gained attention by researchers. However, the abilities of the chelators to remediate the multiple metal polluted soils are less effective. This study employed zero-valent iron nanoparticle (nZVI) to enhance the removal efficiencies of citric (CA), tartaric (TA) and oxalic acids (OA), and evaluate their feasibility. Results showed that metal removal efficiencies increased with the increasing concentration of nZVI and soil-liquid ratio, decreased with the increasing solution pH. The kinetic simulation indicated that pseudo-first-order and pseudo-second-order models could be used for describing the washing processes. Additionally, metal removals were significantly improved by addition of nZVI ( p  < 0.05). The highest enhancements of soil Cd, Pb and Zn removals under solution pH of 4.0, soil-liquid ratio of 1:20 and washing time of 120 min reached 12.83% (OA- nZVI), 24.92% (CA-nZVI) and 11.64% (OA- nZVI) for mine soil, and 19.24% (TA- nZVI), 18.16% (CA-nZVI) and 8.93% (OA- nZVI) for farmland soil, respectively. After soil washing, the exchangeable forms and the environmental risks of residual metals were markedly diminished in soils. Therefore, the combinations of the organic acids and nZVI are the feasible practices to repair the soils contaminated by heavy metals. [ABSTRACT FROM AUTHOR]

Siegesbeckia orientalis L. is a promising species for cadmium (Cd) phytoextraction with large biomass and fast growth rate, while little information about their intracellular mechanisms involved in Cd tolerance and detoxification has been explored. A soil pot experiment with total target Cd concentrations of 0, 10, 50, 100, and 150 mg kg−1 were designed to investigate the subcellular distribution, chemical forms and thiol synthesis characteristics of Cd in S. orientalis. More than 90% of Cd was bound to the soluble fractions (48.4-76.5%) and cell walls (19.9-46.3%). Increasing soil Cd concentrations enhanced Cd sequestration into the cell walls. Most of the Cd (69.8-82.7%) in the plant organ was mainly in the forms of pectate and protein integrated Cd and undissolved Cd phosphate, while a minor portion (6.8-20.9%) was in the forms of the inorganic Cd and the water soluble Cd. Nonprotein thiols and phytochelatins significantly increased with increasing soil Cd treatment levels, while glutathione concentrations had no obvious change trends. Therefore, intracellular detoxification mechanisms of Cd in S. orientalis mainly rely on formation of less toxic Cd chemical forms, store of a large amount of Cd in cell wall and synthesis of thiol compounds. [ABSTRACT FROM AUTHOR]

The flapping of a flag in the wind is a classical fluid-structure problem that concerns the interaction of elastic bodies with ambient fluid. We focus on the desirable experimental results of the flow around the flapping flag. By immersing the elastic yet self-supporting heavy flag into water flow, we use particle image velocimetry (PIV) techniques to obtain the whole flow field around the midspan of the flag interacting with a fluid in periodic state. A unique PIV image processing method is used to measure near-wall flow velocities around a moving elastic flag. There exists a thin flow circulation region on the suction side of the flag in periodic state. This observation suggests that viscous flow models may be needed to improve the theoretical predictions of the flapping flag in periodic state, especially in a large amplitude. [ABSTRACT FROM AUTHOR]

The perturbation induced by a wall-mounted transverse circular cylinder element (TCCE) to a turbulent boundary layer (TBL) is studied using particle image velocimetry (PIV). Measurements are also performed on a smooth wall, which is used as baseline for comparison. The modification of the TBL caused by the sudden perturbation, in a statistical sense, is quantified by comparing the distributions of mean velocity, Reynolds stresses and shape factor in the two geometrical configurations. The impact of the TCCE on the TBL is found to extend more than 9 boundary-layer thickness downstream. Combining the side- and top-view PIV data indicates that the packet-like structures are stretched along the streamwise direction within a flat inclination angle when climbing over the TCCE, and retain their large spatial scales. The separated vortices induced downstream of the TCCE, are quickly lifted up to form the hairpin vortices within strong swirling strength. Then, the robust hairpin packets are generated downstream through the auto-generation scenario, which occupies the low-speed regions beneath the residual hairpin packet’s heads and impairs the process that the low-momentum fluids feed the concentrated vorticity into the residual hairpin heads. Meanwhile, the streamwise-stretched low-momentum regions (LMRs) are redeveloped in the inner layer underneath the new-generated hairpin packets. Further downstream, even though the residual hairpin packets’ heads are merged by the robust hairpin packets, they are not completely dissipated, and still interact with the new-generated hairpin packets in the outer layer to the end of the field of view. [ABSTRACT FROM AUTHOR]

Potentially toxic element (PTE) pollution of urban soils has become the focus of social concern, but the differences of the sources, pollution levels and source-oriented human health risks (HHR) of PTE in urban soils among different urban intensity areas is rarely known. This study explored a comprehensive scheme that combined positive matrix factorization model and source-oriented assessment to quantitatively assess the priority pollution sources and HHR in urban soils from areas with different urbanization intensities. All the average values for PTE concentrations, except for Cr, were higher than their corresponding background values. The contributions made by the four sources (atmospheric deposition, agricultural activities, traffic activities, and natural sources) were relatively similar (22.29–29.89%) in the low urbanization intensity (LUI) area, whereas traffic activities and atmospheric deposition made the greatest contributions in the medium urbanization intensity (MUI) (29.12%) and the high urbanization intensity (HUI) (38.97%) areas, respectively. The geo-accumulation index results revealed that Cd was the most polluting element and the HUI area had the highest pollution levels. The content-oriented assessment of HHR demonstrated that the non-carcinogenic risks were acceptable, but the carcinogenic risks were unacceptable. According to the source-oriented HHR assessment, among the anthropogenic activities, atmospheric deposition contributed the most to carcinogenic risk of children in all areas, and atmospheric deposition, traffic activities and agricultural activities contributed the most to the carcinogenic risk of adults in HUI, MUI and LUI, respectively. This suggest that control measures need to be tailored to the appropriate urbanization intensity to effectively curb PTE pollution caused by anthropogenic activities. [Display omitted] • Contents of the potentially toxic elements (PTEs) increased with urbanization intensity. • Four PTE sources were identified by the PMF model. • High intensity urban areas had the highest PTE carcinogenic and non-carcinogenic risk. • Agricultural activities made the greatest contribution to PTE non-carcinogenic risk. • Atmospheric deposition and natural sources contributed most to PTE carcinogenic risk. [ABSTRACT FROM AUTHOR]

Cuticular wax forms a hydrophobic layer covering aerial plant organs and acting as a protective barrier against biotic and abiotic stresses. Compared with well-known wax biosynthetic pathway, molecular regulation of wax biosynthesis is less known. Here, we show that rice O s WS 1, a member of the membrane-bound O-acyl transferase gene family, involved in wax biosynthesis and was regulated by an osa-mi R 1848. Os WS 1-tagged green fluorescent protein localized to the endoplasmic reticulum (ER). Compared with wild-type rice, O s WS 1 overexpression plants displayed a 3% increase in total wax, especially a 35% increase in very long-chain fatty acids, denser wax papillae around the stoma, more cuticular wax crystals formed on leaf and stem surfaces, pollen coats were thicker and more seedlings survived after water-deficit treatment. In contrast, O s WS 1-RNAi and osa-mi R 1848 overexpression plants exhibited opposing changes. Gene expression analysis showed that overexpression of osa-mi R 1848 down-regulated O s WS 1 transcripts; furthermore, expression profiles of O s WS 1 and osa-mi R 1848 were inversely correlated in the leaf, panicle and stem, and upon water-deficit treatment. These results suggest that O s WS 1 is regulated by osa-mi R 1848 and participates in cuticular wax formation. [ABSTRACT FROM AUTHOR]

Phytosterols are membrane components or precursors for brassinosteroid ( BR) biosynthesis. As they cannot be transported long distances, their homeostasis is tightly controlled through their biosynthesis and metabolism. However, it is unknown whether micro RNAs are involved in their homeostatic regulation., Rice ( Oryza sativa) plants transformed with microRNA osa-miR1848 and its target, the obtusifoliol 14α-demethylase gene, Os CYP51G3, were used to investigate the role of osa-miR1848 in the regulation of phytosterol biosynthesis., osa-miR1848 directs Os CYP51G3 mRNA cleavage to regulate phytosterol and BR biosynthesis in rice. The role of Os CYP51G3 as one of the osa-miR1848 targets is supported by the opposite expression patterns of osa-miR1848 and Os CYP51G3 in transgenic rice plants, and by the identification of Os CYP51G3 mRNA cleavage sites. Increased osa-miR1848 and decreased Os CYP51G3 expression reduced phytosterol and BR concentrations, and caused typical phenotypic changes related to phytosterol and BR deficiency, including dwarf plants, erect leaves, semi-sterile pollen grains, and shorter cells. Circadian expression of osa-miR1848 regulated the diurnal abundance of Os CYP51G3 transcript in developing organs, and the response of Os CYP51G3 to salt stress., We propose that osa-miR1848 regulates Os CYP51G3 expression posttranscriptionally, and mediates phytosterol and BR biosynthesis. osa-miR1848 and OsCYP51G3 might have potential applications in rice breeding to modulate leaf angle, and the size and quality of seeds. [ABSTRACT FROM AUTHOR]

Toxic metal contamination causes a great threat to soil ecosystem and human health. Soil washing is a fast practice for removing metals, but its influences on microbial diversity and the stability of soil ecosystem remain unknown. In this study, ethylenediaminetetraacetic acid (EDTA), citric acid (CA), and fermented pineapple peel residue (FPP) were used as representatives of chelates, low molecular organic acids and biological materials to wash Pb-polluted soils, and their impacts on microbial community were investigated. Washing with these agents effectively removed Pb, but altered microbial community structure. After washing with EDTA, CA, and FPP, 3–8 bacterial phyla and 1 fungal phylum greatly increased, while 7–20 bacterial and 0–6 fungal phyla severely decreased or even disappeared. The alterations of different microbiomes were closely related to soil metal fractions. The labile metal fraction had negative effects on most bacteria and fungi, but also showed positive influences on Actinobacteria , Patescibacteria , and Fusobacteria. The moderately stable and stable fractions were nontoxic to the most microbes, but still harmful to Patescibacteria and Deinococcus-Thermus. These findings provide new insights for the effects of soil washing remediation and toxicity of metal fractions on the microbiomes with different abundance. [Display omitted] • Soil washing altered the diversity and abundance of microbial community. • The rare microbiome was sensitive to removal of metals by washing. • Toxic metal fractions showed diverse effects on different microbes. • The stable fractions were also harmful to some phyla such as Patescibacteria. • The fermented pineapple peel may be as a cleaner and sustainable washing agent. [ABSTRACT FROM AUTHOR]

ABSTRACT With-leaf (WL) storage and selling are becoming increasingly popular with consumers for its attractiveness and freshness. To better understand the changes of quality attributes in fruit stored WL, quality, antioxidant properties and volatile in 'Shatangju' mandarin were determined during the 9-week storage at 5C. WL storage decreased titratable acidity, flavonoid content and antioxidant activity determined by 1-diphenyl-2-picrylhydrazyl but increased ethanol content significantly, whereas WL storage had no significant effects on the content of total soluble solids, acetaldehyde and total phenolics, and reducing power. Furthermore, WL storage decreased the diversity of volatile compounds quickly. Based on the study, 'Shatangju' mandarin fruit WL (packed with polyethylene film and fungicide-treated) could be stored at 5C for up to 7 weeks. To the best of our knowledge, this is the first study thoroughly describing the quality profile of fruit stored WL. PRACTICAL APPLICATIONS This paper reports on the changes of quality, antioxidant activity and volatile compositions of 'Shatangju' mandarin fruit stored with leaves (WLs) attached to the remaining pedicle at a temperature commonly encountered in the industry. From the results obtained, 'Shatangju' mandarin stored WL deteriorates much quicker than without leaf because of faster accumulation of acetaldehyde and ethanol, and decrease in total soluble solids, titratable acidity, total phenolics, flavonoids, 1-diphenyl-2-picrylhydrazyl radical scavenging activity, reducing power and the volatile components. The results of the study suggest that a storage life of 7 weeks at 5C is recommended for commercial usage. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the effects of short-term root-zone hypoxic stress and exogenous calcium application or deficiency in an anoxic nutrient solution on nitrogen metabolism in the roots of the muskmelon cultivar Xiyu No. 1. Seedlings grown in the nutrient solution under hypoxic stress for 6d displayed significantly reduced plant growth and soluble protein concentrations. However, NO3 − uptake rate and activities of nitrate reductase and glutamate synthase were significantly increased. We also found higher amounts of nitrate, ammonium, amino acids, heat-stable proteins, polyamines, H2O2, as well as higher polyamine oxidase activity in the roots. In comparison to the reactions seen under hypoxic stress, exogenous calcium application led to a marked increase in plant weights, photosynthesis parameters, NO3 − uptake rate and contents of nitrate, ammonium, amino acids (e.g., glutamic acid, proline, glycine, cystine, γ-aminobutyric acid), soluble and heat-stable proteins, free spermine, and insoluble bound polyamines. Meanwhile, exogenous calcium application resulted in significantly increased activities for nitrate reductase, glutamine synthetase, and glutamate synthase but decreased activities for diamine and polyamine oxidase, as well as lower H2O2 content in roots during exposure to hypoxia. However, calcium deficiency in the nutrient solution decreased plant weight, photosynthesis parameters, NO3 − reduction, amino acids (e.g., alanine, aspartic acid, glutamic acid, γ-aminobutyric acid), protein, all polyamines except for free putrescine, and the activities of glutamate synthase and glutamine synthetase. Additionally, there was an increase in the NO3 − uptake rate, polyamine oxidase activity and H2O2 contents under hypoxia–Ca. Simultaneously, exogenous calcium had little effect on nitrate absorption and transformation, photosynthetic parameters, and plant growth under normoxic conditions. These results suggest that calcium confers short-term hypoxia tolerance in muskmelon, most likely by promoting nitrate uptake and accelerating its transformation into amino acids, heat-stable proteins or polyamines, as well as by decreasing polyamine degradation in muskmelon seedlings. [Copyright &y& Elsevier]

Chemical washing is considered an effective technique for removing heavy metals (HMs) from industrial sludge. However, traditional washing methods have the potential to cause secondary environmental pollution. In this study, a new chemical washing strategy that circumvents the risk of secondary contamination by using two organic acid polymers—Caboxyethylthiosuccinic acid (CETSA) and itaconic-acrylic acid copolymer (IA-AA) were introduced to remove Pb, Zn, Ni and Cr from industrial sludge. The quantity of HMs removed from the sludge increases as a function of increasing agent concentration, Solid-to-liquid ratio, and washing time, while various trends were observed in response to increasing pH. In addition, response surface analysis showed that CETSA concentration significantly affected HM removal; and IA-AA concentration, pH, and washing time showed evident impacts on washing efficiency. Optimal washing specifications using CETSA, with respect to agent concentration, pH, and washing time, were 66.76 g/L, 2.76, and 248 min, respectively; while those of IA-AA were 100 g/L, 2, and 360 min, respectively. CETSA and IA-AA removed 69.04% and 98.31% of total HMs, respectively, and decreased the labile fractions of Zn and Ni. Fourier transform infrared spectroscopy analysis suggested that the hydroxyl, carboxyl, carbonyl might contribute to the heavy metal extraction. Overall, CETSA and IA-AA should be seriously considered as reliable washing agents for use in HM removal from sludge. [Display omitted] • CETSA and IA-AA can effectively remove Pb, Zn, Ni and Cr from industrial sludge. • Optimal washing specifications were obtained using Response surface methodology. • CTESA and IA-AA washing decreased the labile fraction concentration of heavy metals. [ABSTRACT FROM AUTHOR]

Jasmonic acid (JA) is reportedly involved in the interaction between insects and the vegetative parts of horticultural crops; less attention has, however, been paid to its involvement in the interaction between insects and the floral parts of horticultural crops. Previously, we investigated the allene oxide synthase 2 (AOS2) gene that was found to be the only JA synthesis gene upregulated in tea (Camellia sinensis) flowers exposed to insect (Thrips hawaiiensis (Morgan)) attacks. In our present study, transient expression analysis in Nicotiana benthamiana plants confirmed that CsAOS2 functioned in JA synthesis and was located in the chloroplast membrane. In contrast to tea leaves, the metabolite profiles of tea flowers were not significantly affected by 10 h JA (2.5 mM) treatment as determined using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry, and gas chromatography-mass spectrometry. Moreover, JA treatment did not significantly influence ethylene formation in tea flowers. These results suggest that JA in tea flowers may have different functions from JA in tea leaves and other flowers. [ABSTRACT FROM AUTHOR]

• Metabolic dynamics of L. ruthenicum fruit was monitored using UHPLC-MS/MS. • A total of 49 compounds were tentatively identified in the fruits. • Four developmental stages can be easily distinguished by PCA. • Positive correlation between anthocyanin and spermidine derivative hexoses was found. • The positive correlation was attributed to a glycosyltransferase HG27071. The Lycium ruthenicum (Lr) fruit is a widely used nutritional food that contains various bioactive components such as anthocyanin and spermidine derivatives. In the present study, ultra-high-performance liquid chromatography with tandem mass spectrometry was utilized to profile the metabolic dynamics of four developmental stages of Lr fruit. A total of 49 compounds, including anthocyanin, alkaloids, hydroxycinnamic acid derivatives, flavonoids, and amino acids, were tentatively identified. Principal component analysis distinguished the fruit at four developmental stages using 15 (9 were tentatively identified) potential marker compounds. Pearson correlation analysis suggested that anthocyanin and spermidine derivative hexoses had a strong positive correlation coefficient. A glucosyltransferase (HG27071) was confirmed to glucosylate both anthocyanidin and spermidine derivative in vitro. Our results provide insight into the metabolic linkages among bioactive components in Lr fruits. The glucosyltransferase identified in this study will promote its potential use in functional foods and natural pigment resources. [ABSTRACT FROM AUTHOR]

Soil washing with chelators is a promising and efficient method of remediating metals-contaminated soils. However, the toxicity of residual metals and the effects on soil microbial properties have remained largely unknown after washing. In this study, we employed four biodegradable chelators for removal of metals from contaminated soils: iminodisuccinic acid (ISA), glutamate-N,N-diacetic acid (GLDA), glucomonocarbonic acid (GCA), and polyaspartic acid (PASP). The maximum removal efficiencies for Cd, Pb, and Zn of 85, 55, and 64% and 45, 53, and 32% were achieved from farmland soil and mine soil using biodegradable chelators, respectively. It was found that the capacity of ISA and GLDA to reduce the labile fraction of Cd, Pb, and Zn was similar to that of the conventional non-biodegradable chelator ethylenediaminetetraacetic acid (EDTA). The leachability, mobility, and bioaccessibility of residual metals after washing decreased notably in comparison to the original soils, thus mitigating the estimated environmental and human health risks. Soil β-glucosidase activity, urease activity, acid phosphatase activity, microbial biomass nitrogen, and microbial biomass phosphorus decreased in the treated soils. However, compared with EDTA treatment, soil enzyme activities distinctly increased by 5–94% and overall microbial biomass slightly improved in the remediated soils, which would facilitate reuse of the washed soils. Based on soil toxicity tests that employed wheat seed germination as the endpoint of assessment, the washed soils exhibited only slight effects especially after ISA and GLDA treatments, following high-efficiency metal removal. Hence, ISA and GLDA appear to possess the greatest potential to rehabilitate polluted soils with limited toxicity remaining. [ABSTRACT FROM AUTHOR]

Soil washing, an emerging method for treating soils contaminated by heavy metals, requires an evaluation of its efficiency in simultaneously removing different metals, the quality of the soil following remediation, and the reusability of the recycled washing agent. In this study, we employed N , N -bis (carboxymethyl)- l -glutamic acid (GLDA), a novel and readily biodegradable chelator to remove Cd, Pb, and Zn from polluted soils. We investigated the influence of washing conditions, including GLDA concentration, pH, and contact time on their removal efficiencies. The single factor experiments showed that Cd, Pb, and Zn removal efficiencies reached 70.62, 74.45, and 34.43% in mine soil at a GLDA concentration of 75 mM, a pH of 4.0, and a contact time of 60 min, and in polluted farmland soil, removal efficiencies were 69.12, 78.30, and 39.50%, respectively. We then employed response surface methodology to optimize the washing parameters. The optimization process showed that the removal efficiencies were 69.50, 88.09, and 40.45% in mine soil and 71.34, 81.02, and 50.95% in polluted farmland soil for Cd, Pb, and Zn, respectively. Moreover, the overall highly effective removal of Cd and Pb was connected mainly to their highly effective removal from the water-soluble, exchangeable, and carbonate fractions. GLDA-washing eliminated the same amount of metals as EDTA-washing, while simultaneously retaining most of the soil nutrients. Removal efficiencies of recycled GLDA were no > 5% lower than those of the fresh GLDA. Therefore, GLDA could potentially be used for the rehabilitation of soil contaminated by heavy metals. [ABSTRACT FROM AUTHOR]