As a common heavy metal, chromium and its compounds are widely used in industrial applications, e.g., leather tanning, electroplating, and in stainless steel, paints and fertilizers. Due to the ...strong toxicity of Cr(VI), chromium is regarded as a major source of pollution with a serious impact on the environment and biological systems. The disposal of Cr(VI) by biological treatment methods is more favorable than traditional treatment methods because the biological processes are environmentally friendly and cost-efficient. This review describes how bacteria tolerate and reduce Cr(VI) and the effects of some physical and chemical factors on the reduction of Cr(IV). The practical applications for Cr(VI) reduction of bacterial cells are also included in this review.
Salinity is a major abiotic stress threatening crop production. Root-derived bacteria (RDB) are hypothesized to play a role in enhancing plant adaptability to various stresses. However, it is still ...unclear whether and how plants build up specific RDB when challenged by salinity. In this study, we measured the composition and variation in the rhizosphere and endophyte bacteria of salt-sensitive (SSs) and salt-resistant (SRs) plants under soil conditions with/without salinity. The salt-induced RDB (both rhizobiomes and endophytes) were isolated to examine their effects on the physiological responses of SSs and SRs to salinity challenge. Moreover, we examined whether functional redundancy exists among salt-induced RDB in enhancing plant adaptability to salt stress. We observed that although SSs and SRs recruited distinct RDB and relevant functions when challenged by salinity, salt-induced recruitment of specific RDB led to a consistent growth promotion in plants regardless of their salinity tolerance capacities. Plants employed a species-specific strategy to recruit beneficial soil bacteria in the rhizosphere rather than in the endosphere. Furthermore, we demonstrated that the consortium, but not individual members of the salt-induced RDB, provided enduring resistance against salt stress. This study confirms the critical role of salt-induced RDB in enhancing plant adaptability to salt stress.
Solar greenhouse is a common facility type used for horticultural crop production in China. However, most solar greenhouse fields have been degraded due to continuous cropping and excessive ...fertilizer use. Therefore, we investigated solar greenhouse soils covering a wide range of cultivation years and environmental conditions in Round-Bohai Bay-Region to test the effects of cultivation year and biogeography on nutrients, heavy metals, and phthalate acid esters (PAEs). In general, soil pH decreased while soil electrical conductivity (EC), organic matter (OM), total nitrogen (TN), NO
3
−
-N, NH
4
+
-N, mineral nitrogen (MN), Olsen-P, and NH
4
OAc-K contents increased as time of cultivation increased. However, this trend was influenced by sampling sites. Among sampling sites, Jiangsu showed a relatively low soil pH and high Olsen-P content, while Hebei showed a relatively high soil EC value, NO
3
−
-N, NH
4
+
-N, MN, and NH
4
OAc-K contents. Liaoning was characterized by relatively high soil OM and TN contents. The nutrient level indexes in evaluation of soil quality on Olsen-P and NH
4
OAc-K exceeded the standard seriously. The maximum values of the heavy metals Cd, Cu, and Zn were 4.87, 2.78, and 1.15 times higher than the threshold values, respectively. There was a rising trend on the heavy metal contents with the increasing cultivation years, and this trend was significantly influenced by sampling sites. Both Cu and Zn had relative high heavy metal indexes in evaluation of soil pollution. The PAEs were not detected in almost all sampling soils. Overall, the excessive fertilizer application was an important cause of nutrient accumulation and heavy metal pollution, resulting in soil degradation in solar greenhouses.
Excessive fertilization is a common agricultural practice that often negatively influence soil and environmental quality in intensive vegetable production systems in China. To reduce negative effects ...of excessive fertilization, current studies generally focused on fertilizer management but not irrigation. In this study, we investigated the effects of fertilization and irrigation on soil properties, leaching water characteristics, plant growth, cucumber yield, irrigation water use efficiency (IWUE) and partial factor productivity of nitrogen (PFPN) in a double cropping system. The treatments included (i) conventional irrigation with conventional N fertilization (IcNc), (ii) optimal irrigation with conventional N fertilization (IoNc), (iii) conventional irrigation with optimal N fertilization (IcNo), and (iv) optimal irrigation with optimal N fertilization (IoNo). In general, fertilization merely influenced concentrations of nitrate (NO3-), phosphorus (P) and potassium (K), but did not affect most leaching water characteristics. In contrast, irrigation influenced pH, EC and concentrations of P, K, Ca, Mg, Na and Cu. Cumulative leached amounts of NO3-, P, K, Ca, Mg, Na, Fe, Cu and Zn were significantly decreased by optimal irrigation as compared to conventional irrigation under same fertilization conditions, but not by optimal fertilization as compared to conventional fertilization under same irrigation conditions. The leachate volume was strongly positively correlated with cumulative leached amounts of all tested elements, and these relationships were obviously influenced by irrigation but not fertilization. The IoNo treatment significantly increased both IWUE and PFPN as compared to the IcNc treatment. However, the IcNo treatment only enhanced PFPN, while the IoNc treatment improved IWUE, when compared to the IcNc treatment. Our results suggested that irrigation has more influence than fertilization on leaching water quality and that the optimal irrigation combined with optimal fertilization was efficient in reducing the potential environmental risk caused by excessive fertilization in intensive vegetable production systems.
Rhizosphere microorganisms in soils are important for plant growth. However, the importance of rhizosphere microorganisms is still underestimated since many microorganisms associated with plant roots ...cannot be cultured and since the microbial diversity in the rhizosphere can be influenced by several factors, such as the cropping history, biogeography, and agricultural practice. Here, we characterized the rhizosphere bacterial diversity of cucumber plants grown in soils covering a wide range of cucumber cropping histories and environmental conditions by using pyrosequencing of bacterial 16S rRNA genes. We also tested the effects of compost addition and/or bacterial inoculation on the bacterial diversity in the rhizosphere. We identified an average of approximately 8,883 reads per sample, corresponding to around 4,993 molecular operational taxonomic units per sample. The Proteobacteria was the most abundant phylum in almost all soils. The abundances of the phyla Bacteroidetes, Actinobacteria, Firmicutes, Acidobacteria, and Verrucomicrobia varied among the samples, and together with Proteobacteria, these phyla were the six most abundant phyla in almost all analyzed samples. Analyzing all the sample libraries together, the predominant genera found were Flavobacterium, Ohtaekwangia, Opitutus, Gp6, Steroidobacter, and Acidovorax. Overall, compost and microbial amendments increased shoot biomass when compared to untreated soils. However, compost addition decreased the bacterial α-diversity in most soils (but for three soils compost increased diversity), and no statistical effect of microbial amendment on the bacterial α-diversity was found. Moreover, soil amendments did not significantly influence the bacterial β-diversity. Soil organic content appeared more important than compost and microbial amendments in shaping the structure of bacterial communities in the rhizosphere of cucumber.
ETHNOPHARMACOLOGICAL RELEVANCERhizoma Dioscoreae (RD) is the rhizome of Dioscorea opposita Thunb., a traditional Chinese medicine, which can treat hypertension, diabetes, cerebral vasospasm headache ...and Alzheimer's disease. Meanwhile, RD is the main component of Liuwei Dihuang pill, a Chinese patent medicine. Rhizoma Dioscoreae polysaccharides (RDPS) are the primary active ingredient of RD. Modern medical research confirmed RDPS has multiple pharmacological effects, including neuroprotection, immunoregulation, antioxidant effect in many organs. The primary ischemia/hypoxia injury and secondary reperfusion injury are mainly caused by oxidative stress, which caused by hypoxia, such as free radical generation, energy metabolism disorder, intracellular calcium overload, excitatory amino acid release and inflammatory reaction. AIM OF THE STUDYWe have investigated the pharmacodynamic effect of RDPS on cerebral ischemia-reperfusion (IR) injury in rats and the possible mechanism in vitro. MATERIALS AND METHODSThe pharmacodynamic effect of RDPS on IR injury in rats was studied by the construction of the occlusion of middle cerebral artery (MCAO) model, measuring the volume of cerebral infarct area, the content of oxidation index, inflammatory cytokines, and the expression of CaMMKβ in brain tissue. The in vitro study was explored by oxygen-glucose deprivation/glycogen reoxygenation (OGD/R) model, construction of the CaMMKβ interference sequence, measuring the expression of CaMMKβ in BV2 cells before and after inhibition of CaMMKβ, and the influence of RDPS on Nrf2/HO-1 signal pathway, in order to investigate the possible mechanism. RESULTSCompared with the model group, the present study showed that RDPS with high-dose and low-dose groups could significantly reduce the volume of cerebral infarction. The content of MDA decreased and the activities of GSH and SOD increased in the two dose groups of RDPS. We confirmed that after RDPS treatment, the levels of IL-6, IL-1 β and TNF-α in brain tissue were lower than those in model group, and the expression of CaMMKβ in brain tissue of rats decreased in the model group, but increased in the groups of RDPS. In the in vitro study, compared with the control group, RDPS could regulate the OGD/R-induced apoptosis of BV2 cells and increase the level of CaMMKβ, Nrf2 and HO-1 induced by OGD/R. To our surprise, these therapeutic effects are no longer present after the inhibition of CaMMKβ protein. The activity of BV2 induced by OGD/R could not be enhanced by RDPS after the inhibition of CaMMKβ protein. CONCLUSIONSRDPS has the pharmacodynamic effect in IR injury, which reduce the area of cerebral infarction, up-regulate the activity of anti-oxidant kinase, and down-regulate the inflammatory cytokine. Additionally, RDPS could affect the activation of Nrf2/HO-1 signaling pathway by regulating the expression of CaMMKβ. Our observations justify the RDPS could be a new strategy for IR injury therapy, and the mechanism may be related to the improvement of antioxidant enzyme activity and inhibition of inflammatory reaction.
Spectrum-based fault localization (SBFL) techniques are widely studied and have been evaluated to be effective in locating faults. Recent studies also showed that developers from industry value ...automated SBFL techniques. However, their effectiveness is still limited by two main reasons. First, the test coverage information leveraged to construct the spectrum does not reflect the root cause directly. Second, SBFL suffers from the tie issue so that the buggy code entities can not be well differentiated from non-buggy ones. To address these challenges, we propose to leverage the information of version histories in fault localization based on the following two intuitions. First, version histories record how bugs are introduced to software projects and this information reflects the root cause of bugs directly. Second, the evolution histories of code can help differentiate those suspicious code entities ranked in tie by SBFL. Our intuitions are also inspired by the observations on debugging practices from large open source projects and industry. Based on the intuitions, we propose a novel technique HSFL (historical spectrum based fault localization). Specifically, HSFL identifies bug-inducing commits from the version history in the first step. It then constructs historical spectrum (denoted as Histrum) based on bug-inducing commits, which is another dimension of spectrum orthogonal to the coverage based spectrum used in SBFL. HSFL finally ranks the suspicious code elements based on our proposed Histrum and the conventional spectrum. HSFL outperforms the state-of-the-art SBFL techniques significantly on the Defects4J benchmark. Specifically, it locates and ranks the buggy statement at Top-1 for 77.8 percent more bugs as compared with SBFL, and 33.9 percent more bugs at Top-5. Besides, for the metrics MAP and MRR, HSFL achieves an average improvement of 28.3 and 40.8 percent over all bugs, respectively. Moreover, HSFL can also outperform other six families of fault localization techniques, and our proposed Histrum model can be integrated with different families of techniques and boost their performance.
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•Groundwater chemistry and quality were analyzed in the Ningxia region.•NO3−, NH4+ and NO2− are related to human pollution.•Water quality was assessed using an integrated weight ...matter-element extension model.•High health risks of F−, NO3−, NH4+, and NO2− were found, especially for children.
Assessing groundwater quality and identifying pollutant risks are essential for managing groundwater resources in arid and semi-arid regions. An analysis of the hydrochemical characteristics, controlling factors, and pollutant characteristics of the groundwater in the upper Yellow River region is presented to understand the overall groundwater quality and identify the risk to human health in this region. Traditional hydrochemical analysis methods, integrated weight matter-element extension analysis, and health risk models were used in this study. A total of 210 groundwater samples were collected from the wells for physical and chemical analyses. Results showed that groundwater in the study area was weakly alkaline, with the predominant hydrochemical types of groundwater being SO4·Cl-Ca·Mg, SO4·Cl-Na, and HCO3-Ca·Mg. The hydrochemical composition of the groundwater is controlled by rock dominance, evaporation dominance, and cation exchange. Nitrogen pollution of groundwater is caused by industrial activities and fertilizers; fluorine pollution is caused by fluorite dissolution. To reasonably evaluate the groundwater quality, the groundwater evaluation method based on an integrated weight matter-element extension analysis was optimized. The method effectively avoids defects of G1 and entropy weight methods in determining weights and thoroughly considers the fuzziness and uncertainty of the water quality grade. The overall quality groundwater assessment results showed that 96.19% of the overall water quality in the study area was good and could be used in many ways. Land irrigated with groundwater is mainly exposed to salinity hazards. Health risk assessment results showed that 57% and 21% of the samples posed unacceptable health risks to children and adults, respectively. Therefore, more attention should be paid to real-time, continual monitoring of pollutants in groundwater management. The results help decision makers make wise decisions on identifying groundwater purposes to avoid further water quality deterioration and increase in pollutants, ensuring the cleanliness of groundwater resources in the upper Yellow River..
Aims
Root rot caused by Fusarium solani is an important disease seriously affecting the yield and quality of Astragalus membranaceus. Therefore, this study was performed to elucidate the antifungal ...activities and mechanisms of cinnamaldehyde treatment against F. solani and its control effect for A. membranaceus root rot.
Methods and Results
Cinnamaldehyde significantly inhibited mycelial growth and spore germination of F. solani in dose‐dependent, and the median effective concentration was 178.68 μl l−1. Furthermore, scanning electron microscopy, propidium iodide staining, cell leakage experiments and ergosterol quantitation illuminated that cinnamaldehyde could alter the mycelial morphology, damage the plasma membrane and hinder the biosynthesis of ergosterol. Besides, cinnamaldehyde induced the generation of reactive oxygen species by synergistically upregulating the genes encoded subunits for NADPH oxidase. The disease suppression efficacy of 600 μl l−1 cinnamaldehyde against A. membranaceus root rot was 92.98 ± 6.08% (p < 0.05) under greenhouse conditions.
Conclusions
This study proved that cinnamaldehyde could markedly inhibit the growth of F. solani in vitro and effectively suppress the occurrence of A. membranaceus root rot, perhaps by inducing oxidative damage, which results in the distortion of F. solani, and the destruction of cell membrane integrity and permeability.
Significance and Impact of the Study
This study first explores the antifungal mechanisms of cinnamaldehyde against F. solani in vivo and vitro, thereby providing a promising candidate for disease biocontrol.
Rockwool (RC) and peat are two common substrates used worldwide in horticultural crop production. In recent years environmental and ecological concerns raised the demand for reducing the use of RC ...and peat. Although coconut coir (CC) has been increasingly used as an alternative to RC and peat, it is still needed to comprehensively evaluate the feasibility of CC before widely used. To meet this need, CC, RC, and peat-vermiculite (PVC) cultivations were used as tomato cultivation substrates to evaluate their effects on EC, pH and mineral ions in root-zone solution and drainage, nutrient uptake by crops, nutrient balance of cultivation system, plant growth and fruit quality. In general, CC significantly increased K and S uptake by crops, photosynthesis, individual fruit weight and total fruit yield compared to RC, and increased P and K uptake by crops and total fruit yield compared to PVC. Moreover, CC significantly increased organic acid of fruit in first truss compared to both RC and PVC. The uncredited nutrient was overally lower under CC than under RC and PVC (the lower, the better). For all substrates, the blossom-end rot (BER) of fruit increased gradually from 3rd to 13th trusses. The BER of fruit was not significantly influenced by CC compared to RC or PVC, but was sginificantly decreased by PVC compared to RC. Our results infer that CC was a potential substrate that could be widely used in tomato production. However, the inhibition of BER was still a challenge when CC was used as cultivation substrate for tomato.
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