Search

Aerosol ultra-fine and nano-particles are playing essential roles in the evolution of the Earth environment because of their deep connections to the chemical conversions and solar radiation energy transfer in the atmosphere, and have also become an urgent public concern in recent years due to their adverse health effects. Electron microscopes, as major tools being able to accurately identify the physical and chemical characteristics of individual particles in micron and submicron size, have been widely used in aerosol studies, although some barriers remain for their low efficiency and high cost. In this work, current understandings on the physical and chemical characteristics, mixing state and heterogeneous chemical reactions of individual aerosol particles, mainly obtained with electron microscopes, are reviewed. First, the techniques of individual particle analyses are briefly summarized and their advantages and disadvantages are discussed. Then, the morphology and composition of major atmospheric particle types obtained with these techniques and how the information was used to identify particle sources are introduced. The effects of aerosol particles on the environment, climate, human health, and global geochemical cycles are also discussed based on the data from individual particle analyses. Finally, challenges faced in individual particle studies are prospected.

In longwall top-coal caving (LTCC) mining, progressive failure process of top coal is closely related to the mining-induced stress. In order to achieve failure mechanisms of the top coal, stress di...

Environmental approaches for minimizing wheat grain Cd are urgently in need in many parts of the world. While metal-removing strategies like phytoextraction or soil-washing are not suitable to the scenario of farmland Cd pollution, rhizoremediation which aims to reduce crops’ Cd uptake by using microbial technology has shown great potentials. In this study, a filamentous fungus strain YZ1 was isolated from wheat farmland soil, which is affiliated to Purpureocillium sp. based on morphological and phylogenetical evidence. The strain YZ1 had a minimum inhibitory concentration of 1 mM Cd and was able to survive at 100 mM Cd, with maximum biomass at 0.4 mM Cd. Comparative transcriptomics showed that little changes in cellular transcriptional patterns occurred at 0.4 mM Cd relative to the control, and substantial transcriptional changes could be detected mainly in substance metabolism/transport genes at 2 mM Cd. Pot culture experiments showed that YZ1 rhizo-inoculation ameliorated Cd stress to wheat substantially, leading to a significant reduction by 23.3% to 26.0% in Cd concentration of wheat seedlings. Further, molecular evidence indicated that YZ1 may colonize the wheat root and impact wheat Cd response by modulating wheat’s Cd-associated genes, mainly TaEXPA2, TaVP1, TaMRP3, TaPCS1 and TaTM20, while no effect of YZ1 on culture medium pH or Cd bioavailability was observed. A fungal strain YZ1 showing Cd-loving nature was isolated. The strain YZ1 can be a promising candidate for rhizoremediation of Cd-contaminated farmland in wheat-production areas.

Drought is a major natural disaster that seriously affects agricultural production, especially for winter wheat in boreal China. As functional proteins, the functions and mechanisms of glyceraldehyde-3-phosphate dehydrogenase in cytoplasm (GAPCs) have remained little investigated in wheat subjected to adverse environmental conditions. In this study, we cloned and characterized a GAPC isoform TaGAPC2 in wheat. Over-expression of TaGApC2-6D in Arabidopsis led to enhanced root length, reduced reactive oxygen species (ROS) production, and elevated drought tolerance. In addition, the dual-luciferase assays showed that TaWRKY28/33/40/47 could positively regulate the expression of TaGApC2-6A and TaGApC2-6D. Further results of the yeast two-hybrid system and bimolecular fluorescence complementation assay (BiFC) demonstrate that TaPLD&delta, an enzyme producing phosphatidic acid (PA), could interact with TaGAPC2-6D in plants. These results demonstrate that TaGAPC2 regulated by TaWRKY28/33/40/47 plays a crucial role in drought tolerance, which may influence the drought stress conditions via interaction with TaPLD&delta, In conclusion, our results establish a new positive regulation mechanism of TaGAPC2 that helps wheat fine-tune its drought response.

Climate change profoundly influences the geospatial distribution of secondary metabolites and causes the geographical migration of plants. We planted seedlings of the same species in eighteen ecological regions along a latitudinal gradient in eastern and western China, in order to explore the regulation of multi-climatic factors on active ingredient accumulation in Salvia miltiorrhiza Bunge. The correlations between six active ingredient contents and ten climatic factors were investigated to clarify their relationships. We found that climatic factors not only regulated active ingredient contents but also markedly influenced their composition and led to a specific geospatial distribution of these active ingredients in China. The main climatic factors include the air temperature, precipitation, atmospheric vapour pressure and sunshine duration. Future warming in high-latitude regions could cause continued northward expansion of planting areas suitable for S. miltiorrhiza. The effect of extreme climatic conditions on active ingredients should not be overlooked. The findings of this study can help farmers scientifically choose suitable cultivation regions in the future. Furthermore, this study provides an innovative idea for the exploration of secondary metabolic responses to changing ecological factors in medicinal plants.

Soluble iron (FeS) in aerosols contributes to free oxygen radical generation with implications for human health, and potentially catalyzes sulfur dioxide oxidation. It is also an important external source of micronutrients for ocean ecosystems. However, factors controlling FeS concentration and its contribution to total iron (FeT) in aerosols remain poorly understand. Here, FeS and FeT in PM2.5 was studied at four urban sites in eastern China from 21 to 31 December, 2017. Average FeT (869–1490 ng m−3) and FeS (24–68 ng m−3) concentrations were higher in northern than southern China cities, but Fe solubility (%FeS, 2.7–5.0%) showed no spatial pattern. Correlation analyses suggested %FeS was strongly correlated with FeS and PM2.5 instead of FeT concentrations. Individual particle observations confirmed that more than 65% of nano-sized Fe-containing particles were internally mixed with sulfates and nitrates. Furthermore, there was a high correlation between sulfates or nitrates/FeT molar ratio and %FeS. We also found that the sulfates/nitrates had weaker effects on %FeS at RH 50%, suggesting RH as indirect factor can influence %FeS in PM2.5. These results suggest an important role of chemical processing in enhancing %FeS in the polluted atmosphere.

The minimization of Cd pollution in wheat is urgently needed in many parts of the world. Thus, the aims of the present study were to evaluate the feasibility of popular technologies (i.e., soil amendment and low-Cd wheat cultivar) at sites with different Cd risk levels (high and low) and to propose a risk-based strategy for safe grain production. At a high-Cd site, wheat variety JM22 yielded significantly lower grain Cd than SX828, regardless of soil amendment (biochar, sepiolite, and microbial agent YZ1). Neither biochar nor sepiolite amendment reduced grain Cd, DTPA-Cd, or bioconcentration factors, possibly due to low dosage. Metagenomic sequencing and quantitative PCR showed that YZ1 colonization had little effect on rhizospheric fungal community structure and could not be sustained through winter. At a low-Cd site, significantly lower grain Cd was observed in JM22, LX99, and JM262, which could be used as low-Cd cultivars in the study area. Interestingly, the grain Cd of JM22 was linearly correlated with soil Cd (R2 = 0.84), which allowed the inference of a soil Cd threshold of 1.55 mg·kg−1, below which JM22 alone was capable of producing safe grain. Cost-benefit analysis also indicated that the use of low-Cd cultivars is promising for pollution control. This study provides viable technical solutions for minimizing the grain Cd of wheat grown in northern China.

Backgrounds Drought stress is one of the major factors that affects wheat yield. Glyceraldehyde-3-Phosphate dehydrogenase (GAPDH) is a multifunctional enzyme that plays the important role in abiotic stress and plant development. However, in wheat, limited information about drought-responsive GAPC genes has been reported, and the mechanism underlying the regulation of the GAPC protein is unknown. Results In this study, we evaluated the potential role of GAPC1 in drought stress in wheat and Arabidopsis. We found that the overexpression of TaGAPC1 could enhance the tolerance to drought stress in transgenic Arabidopsis. Yeast one-hybrid library screening and EMSA showed that TaWRKY40 acts as a direct regulator of the TaGAPC1 gene. A dual luciferase reporter assay indicated that TaWRKY40 improved the TaGAPC1 promoter activity. The results of qRT-PCR in wheat protoplast cells with instantaneous overexpression of TaWRKY40 indicated that the expression level of TaGAPC1 induced by abiotic stress was upregulated by TaWRKY40. Moreover, TaGAPC1 promoted H2O2 detoxification in response to drought. Conclusion These results demonstrate that the inducible transcription factor TaWRKY40 could activate the transcription of the TaGAPC1 gene, thereby increasing the tolerance of plants to drought stress.

Background Drought stress is one of the major abiotic stresses that affects plant growth and productivity. The GAPCp genes play important roles in drought stress tolerance in multiple species. The aim of this experiment was to identify the core cis-regulatory elements that may respond to drought stress in the GAPCp2 and GAPCp3 promoter sequences. Results In this study, the promoters of GAPCp2 and GAPCp3 were cloned. The promoter activities were significantly improved under abiotic stress via regulation of Rluc reporter gene expression, while promoter sequence analysis indicated that these fragments were not almost identical. In transgenic Arabidopsis with the expression of the GUS reporter gene under the control of one of these promoters, the activities of GUS were strong in almost all tissues except the seeds, and the activities were induced after abiotic stress. The yeast one-hybrid system and EMSA demonstrated that TaMYB bound TaGAPCp2P/3P. By analyzing different 5′ deletion mutants of these promoters, it was determined that TaGAPCp2P (− 1312~ − 528) and TaGAPCp3P (− 2049~ − 610), including the MYB binding site, contained enhancer elements that increased gene expression levels under drought stress. We used an effector and a reporter to co-transform tobacco and found that TaMYB interacted with the specific MYB binding sites of TaGAPCp2P (− 1197~ − 635) and TaGAPCp3P (− 1456~ − 1144 and − 718~ − 610) in plant cells. Then, the Y1H system and EMSA assay demonstrated that these MYB binding sites in TaGAPCp2P (− 1135 and − 985) and TaGAPCp3P (− 1414 and − 665) were the target cis-elements of TaMYB. The deletion of the specific MYB binding sites in the promoter fragments significantly restrained the drought response, and these results confirmed that these MYB binding sites (AACTAAA/C) play vital roles in improving the transcription levels under drought stress. The results of qRT-PCR in wheat protoplasts transiently overexpressing TaMYB indicated that the expression of TaGAPCp2/3 induced by abiotic stress was upregulated by TaMYB. Conclusion The MYB binding sites (AACTAAA/C) in TaGAPCp2P/3P were identified as the key cis-elements for responding to drought stress and were bound by the transcription factor TaMYB.

Drought is a major threat to wheat growth and crop productivity. However, there has been only limited success in developing drought-hardy cultivars. This lack of progress is due, at least in part, to a lack of understanding of the molecular mechanisms of drought tolerance in wheat. Here, we evaluated the potential role of three cytosolic glyceraldehyde-3-phosphate dehydrogenases (TaGAPC2/5/6) under drought stress in wheat and Arabidopsis. We found that TaGAPC2/5/6 all positively responded to drought stress via reactive oxygen species (ROS) scavenging and stomatal movement. The results of yeast co-transformation and electrophoretic mobility shift assay showed that TaWRKY33 acted as a direct regulator of TaGAPC2/5/6 genes. The dual luciferase reporter assay indicated that TaWRKY33 positively activated the expression of TaGAPC2/5/6. The results of bimolecular fluorescence complementation and yeast two-hybrid system demonstrated that TaGAPC2/5/6 interacted with phospholipase Dδ (PLDδ). We then demonstrated that TaGAPC2/5/6 positively promoted the activity of TaPLDδ in vitro and in vivo. Furthermore, lower PLDδ activity in RNAi wheat could lead to less PA accumulation, causing higher stomatal aperture sizes under drought stress. In summary, our results establish a new positive regulatory mechanism of TaGAPCs which helps wheat fine-tune their drought responses.

Heavy metal risks to human health in farmland of wastewater-irrigated areas have long been recognized. It remains to be shown whether farmland heavy metals from wastewater irrigation can migrate to deeper soil at a regional scale. In this study, nine soil cores deep to 30 m from three transects (A, B and C) of a linear wastewater reservoir and the adjacent farmland topsoils and wheat grains were sampled. Heavy metals including As, Cd, Cr, Cu, Pb and Zn in the soils and wheat grains were determined, and the grains’ health risks were assessed using the Target Hazard Quotient (THQ). Considerably high contents of heavy metals in both total and soluble forms were detected in deep soils, especially for the transect B where total As of 73.0 mg kg−1 at 29 m, Cd of 3.80 mg kg−1 at 13 m and Pb of 214 mg kg−1 at 30 m were detected. The silty clayey and silty layers of the transect B had higher contents of As, Cr, Cu, Pb and Zn compared with the sandy layers. Across the studied area, 19.5%–34.1% of the topsoil samples were contaminated by As, Cd, Cu, Pb and Zn, and 34.1% and 19.5% of the wheat grains were contaminated by Cd and Pb, respectively. Wheat grains from all the sampling sites had a combined target hazard quotient (TTHQ) value of >1, with As and Cd being the most important contributors. Our study revealed a wider and deeper risk of typical heavy metals originated from long-term wastewater irrigation in the sampling area, which may pose substantial health risks to the local residents via wheat grains and groundwater.

The atmospheric pollution created by coal-dominated industrial cities in China cannot be neglected. This study focuses on the atmospheric PM10 in the typical industrial city of Pingdingshan City in North China. A total of 44 PM10 samples were collected from three different sites (power plant, mining area, and roadside) in Pingdingshan City during the winter of 2013, and were analyzed gravimetrically and chemically. The Pingdingshan PM10 samples were composed of mineral matter (average of 118.0±58.6μg/m(3), 20.6% of the total PM10 concentration), secondary crystalline particles (338.7±122.0μg/m(3), 59.2%), organic matter (77.3±48.5μg/m(3), 13.5%), and elemental carbon (38.0±28.3μg/m(3), 6.6%). Different sources had different proportions of these components in PM10. The power plant pollutant source was characterized by secondary crystalline particles (377.1μg/m(3)), elemental carbon (51.5μg/m(3)), and organic matter (90.6μg/m(3)) due to coal combustion. The mining area pollutant source was characterized by mineral matter (124.0μg/m(3)) due to weathering of waste dumps. The roadside pollutant source was characterized by mineral matter (130.0μg/m(3)) and organic matter (81.0μg/m(3)) due to road dust and vehicle exhaust, respectively. A positive matrix factorization (PMF) analysis was performed for PM10 source apportionment to identify major anthropogenic sources of PM10 in Pingdingshan. Six factors-crustal matter, coal combustion, vehicle exhaust and abrasion, local burning, weathering of waste dumps, and industrial metal smelting-were identified and their contributions to Pingdingshan PM10 were 19.0%, 31.6%, 7.4%, 6.3%, 9.8%, and 25.9%, respectively. Compared to other major cities in China, the source of PM10 in Pingdingshan was characterized by coal combustion, weathering of waste dumps, and industrial metal smelting.

Drought stress is one of the major abiotic stresses that affects plant growth and productivity. The GAPCp genes play important roles in drought stress tolerance in multiple species. The aim of this experiment was to identify the core cis-regulatory elements that may respond to drought stress in the GAPCp2 and GAPCp3 promoter sequences. In this study, the promoters of GAPCp2 and GAPCp3 were cloned. The promoter activities were significantly improved under abiotic stress via regulation of Rluc reporter gene expression, while promoter sequence analysis indicated that these fragments were not almost identical. In transgenic Arabidopsis with the expression of the GUS reporter gene under the control of one of these promoters, the activities of GUS were strong in almost all tissues except the seeds, and the activities were induced after abiotic stress. The yeast one-hybrid system and EMSA demonstrated that TaMYB bound TaGAPCp2P/3P. By analyzing different 5′ deletion mutants of these promoters, it was determined that TaGAPCp2P (− 1312~ − 528) and TaGAPCp3P (− 2049~ − 610), including the MYB binding site, contained enhancer elements that increased gene expression levels under drought stress. We used an effector and a reporter to co-transform tobacco and found that TaMYB interacted with the specific MYB binding sites of TaGAPCp2P (− 1197~ − 635) and TaGAPCp3P (− 1456~ − 1144 and − 718~ − 610) in plant cells. Then, the Y1H system and EMSA assay demonstrated that these MYB binding sites in TaGAPCp2P (− 1135 and − 985) and TaGAPCp3P (− 1414 and − 665) were the target cis-elements of TaMYB. The deletion of the specific MYB binding sites in the promoter fragments significantly restrained the drought response, and these results confirmed that these MYB binding sites (AACTAAA/C) play vital roles in improving the transcription levels under drought stress. The results of qRT-PCR in wheat protoplasts transiently overexpressing TaMYB indicated that the expression of TaGAPCp2/3 induced by abiotic stress was upregulated by TaMYB. The MYB binding sites (AACTAAA/C) in TaGAPCp2P/3P were identified as the key cis-elements for responding to drought stress and were bound by the transcription factor TaMYB.

Drought is one of the most common abiotic stresses, and can limit wheat yield, crops and productivity. GAPCs play vital roles under drought stress conditions in multiple species. The aim of this experiment was to determine the regulatory mechanism of TaGAPC5 under drought stress. In this study, the genes and promoters of TaGAPC5 in diverse drought-tolerant cultivars were cloned. The amino acid sequences were conserved, while the promoter fragments were not identical. Under abiotic stress, the expression level of TaGAPC5 was substantially different among the diverse drought-tolerant cultivars and the promoter activities were significantly improved. The yeast one-hybrid system and Electrophoretic mobility shift assay (EMSA) demonstrated that TaWRKYs bound to specific W-boxes: TaWRKY28, TaWRKY33, TaWRKY40 and TaWRKY47 bind to G/ATGACG/C/A, C/G/ATGACG, C/ATGACC and C/ATGACC/G, respectively. By analyzing different 5' deletion mutants of these promoters, it was determined that these W-boxes in CW-TaGAPC5 promoter (-1262, -1202, -904, -880 and -207) and ZY-TaGAPC5 promoter (-697 and -220) bound by these four TaWRKYs and were functional under drought stress. The deletion or addition of specific W-boxes in the promoter fragments significantly restrained or advanced the promoter activity under drought stress, and these results further confirmed that these W-boxes play vital roles in improving transcription levels under drought stress. The W-boxes in CW-TaGAPC5P (-1262, -1202, -904, -880 and -207) and ZY-TaGAPC5P (-697 and -220) were identified as the key cis-elements for responding to drought stress and were bound by the transcription factor TaWRKY.

Figure S3 A phylogenetic tree of MYB TFs. A total of 169 sequences were analyzed including one sequences of wheat MYB TFs derived from cDNAs cloned in this work. (GenBank accessions shown in the figure). (PDF 136 kb)

Additional file 3: Table S1. Primer and probe sequences used in this study.

Figure S4 Analysis of functional MYB cis-elements in the TaGAPCp2 and TaGAPCp3 promoters. (DOCX 246 kb)

Table S1 Primer and probe sequences used in this study. (DOCX 17 kb)

Figure S2 Detection of transgenic plant. a PCR analysis of TaGAPCp2P transgenic Arabidopsis. b PCR analysis of TaGAPCp3P transgenic Arabidopsis. (DOCX 159 kb)

Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) serves as a plentiful leaf protein which functions in both eukaryote and prokaryote photosynthesis. The small subunits of Rubisco (RBCS) exist as a multigene family which regulates the catalytic efficiency of holoenzyme. Here, 20 RBCS family genes were identified in Triticum aestivum genome, and were clustered into 4 clades according to phylogenetic analysis. On the basis of the identified 9 and 8 RBCSs in Triticum urartu and Aegilops tauschii, homology analysis revealed some TaRBCS genes were orthologous to TuRBCSs and AetRBCSs, and the number of in-paralog pairs between RBCSs in wheat were much more than that in T. urartu or A. tauschii. Gene structure, protein motif and cis-acting element analysis exhibited that TaRBCSs in each clade shared some identity. The in silico expression of RBCS genes showed that RBCSs mainly expressed in leaf, flower and caryopsis. Quantitative real-time PCR analysis showed that TaRBCSs were remarkably responsive to drought, salt, ABA and darkness stresses. The work comprehensively studies the RBCS family genes in wheat, and lays the foundation for subsequent functional research of TaRBCSs.

PM10 samples were collected on haze days (visibility

To enrich the resource pool of endophytic fungi from plants which produce taxol, a taxol-producing endophytic fungus TMS-26 was isolated from the stem of Taxus Media. The result of high performance liquid chromatography (HPLC) showed that TMS-26 extract exhibited similar chromatographic peaks and retention time (4.545 min) with authentic taxol. Then mass spectrometry (MS) analysis further confirmed that TMS-26 extracts contained the same mass peaks with authentic taxol ((M+Na)+=876). These indicated that the isolated endophytic fungus TMS-26 can produce taxol. According to the morphological characteristics, the molecular analysis of 18S rDNA and internal transcribed spacer nuclear rDNA gene sequence, the fungus was identified as Aspergillus fumigatus TMS-26.为丰富产紫杉醇植物内生真菌资源库，从曼地亚红豆杉Taxus media 茎中分离得到一株产紫杉醇的内生真菌TMS-26。通过对TMS-26 的发酵提取物进行高效液相色谱分析，发现其具有与紫杉醇标准品 (4.545 min)相近的色谱特征峰。进一步通过液质联用仪检测发现，内生真菌TMS-26 的发酵提取物中具有与紫杉醇标准品((M+Na)+=876) 相近的质谱特征峰，表明内生真菌TMS-26 能够产生紫杉醇。同时通过传统形态学分类鉴定方法和18S rDNA 序列分析、Internal-transcribed spacer (ITS) 序列分析等现代分子生物学分类鉴定方法，最终将内生真菌TMS-26 鉴定为曲霉属烟曲霉Aspergillus fumigatus，并命名为“烟曲霉TMS-26”。.

A total of 19 24-h PM 10 samples, the 11 for a typical coal industrial city and 8 for a non-coal industrial city, were collected by a TSP-PM 10 sampler during a serious and continuous haze event in Henan Province, North China. An X-ray diffractometer (XRD) was used to determine the mineralogy and a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer (SEM-EDS) was used to determine the morphology and chemical composition of the PM 10 samples. The crystalline phases that were identified by XRD mainly include sulfate (dominated by koktaite, boussingaultite, gypsum, etc.) and silicate (quartz and kaolinite) as well as small amount of chloride (sal-ammoniac). Silicate particles mainly originate from crust as well as waste dumps for coal industrial cities, and usually have an irregular shape, while sulfate particles occur as individual sheets or needles, and have an anthropogenic origin, which are the products of chemical reaction of preexisting carbonate with SO 2 emitted by coal combustion. Nitrogen, S and Cl occurring in particulate matter are considered to have an anthropogenic origin due to their high enrichment factors, and their abundance in particulate matter is associated with coal industrial activities. Nitrogen mainly occurs as NH 4 + in sulfate, as well as in small amount of organic matter. Sulfur mainly occurs as SO 4 2 − in sulfate. Chlorine mainly occurs in chloride.

Plastidial glyceraldehyde-3-phosphate dehydrogenase (GAPDH, GAPCp) are ubiquitous proteins that play pivotal roles in plant metabolism and are involved in stress response. However, the mechanism of GAPCp&rsquo, s function in plant stress resistance process remains unclear. Here we isolated, identified, and characterized the TaGAPCp1 gene from Chinese Spring wheat for further investigation. Subcellular localization assay indicated that the TaGAPCp1 protein was localized in the plastid of tobacco (Nicotiana tobacum) protoplast. In addition, quantitative real-time PCR (qRT-PCR) unraveled that the expression of TaGAPCp1 (GenBank: MF477938.1) was evidently induced by osmotic stress and abscisic acid (ABA). This experiment also screened its interaction protein, cytochrome b6-f complex iron sulfite subunit (Cyt b6f), from the wheat cDNA library using TaGAPCp1 protein as a bait via the yeast two-hybrid system (Y2H) and the interaction between Cyt b6f and TaGAPCp1 was verified by bimolecular fluorescence complementation assay (BiFC). Moreover, H2O2 could also be used as a signal molecule to participate in the process of Cyt b6f response to abiotic stress. Subsequently, we found that the chlorophyll content in OE-TaGAPCp1 plants was significantly higher than that in wild type (WT) plants. In conclusion, our data revealed that TaGAPCp1 plays an important role in abiotic stress response in wheat and this stress resistance process may be completed by H2O2-mediated ABA signaling pathway.

Oxidative damage to plasmid DNA induced by airborne PM10 (particulate matter with an aerodynamic diameter of 10 μm or less) is caused by the bioavailable (i.e., soluble) heavy metals on the particle surface. However, quantitative analyses of the links between PM10 and oxidative damage are limited. In this study, plasmid DNA assay and ICP-MS were applied to study oxidative capacity and trace element compositions, respectively, of summer and winter PM10 samples collected at several sites (Sun Yat Sen Municipal Park (SYSP) and Av. de Horta e Costa (AHC) on the Macao peninsula and Macao University on Taipa Island (TI)) in Macao. At AHC and TI, the oxidative capacity of PM10 collected in winter was higher than that collected in summer, for both the whole sample and the water-soluble fraction. In contrast, no seasonal variation was noted at SYSP. PM10 exhibited the highest oxidative capacity at SYSP and lowest oxidative capacity at TI in both seasons, demonstrating that the PM10 collected on the Macao peninsula had a higher toxicity than that from Taipa Island. ICP-MS analyses revealed that the concentrations of total analyzed trace elements and their water-soluble components in PM10 from TI and AHC were higher in winter than in summer, whereas SYSP displayed the opposite trend. The extents of oxidative damage induced by the water-soluble fractions and intact whole particles were generally similar, implying that the oxidative damage caused by particles in Macao resulted mainly from the water-soluble fraction. The oxidative capacities of PM10 were positively correlated with both whole and soluble Zn at the 95% confidence level, indicating that Zn was the major element responsible for the oxidative damage caused by particles in Macao. Other heavy metals, such as Cr, Cu, Cd, Ni, As, and Pb, also exhibited elevated concentrations, and the potential health impacts of these metals should be considered.

Background Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a central enzyme in glycolysi, we performed genome-wide identification of GAPDH genes in wheat and analyzed their structural characteristics and expression patterns under abiotic stress in wheat. Results A total of 22 GAPDH genes were identified in wheat cv. Chinese spring; the phylogenetic and structure analysis showed that these GAPDH genes could be divided into four distinct subfamilies. The expression profiles of GAPDH genes showed tissue specificity all over plant development stages. The qRT-PCR results revealed that wheat GAPDHs were involved in several abiotic stress response. Conclusions Wheat carried 22 GAPDH genes, representing four types of plant GAPDHs (gapA/B, gapC, gapCp and gapN). Whole genome duplication and segmental duplication might account for the expansion of wheat GAPDHs. Expression analysis implied that GAPDHs play roles in plants abiotic stress tolerance. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2527-3) contains supplementary material, which is available to authorized users.

Cytosolic glyceraldehyde-3-phosphate dehydrogenase (GAPC) catalyzes a key reaction in glycolysis and encoded by a multi-gene family which showed instability expression under abiotic stress. DNA methylation is an epigenetic modification that plays an important role in gene regulation in response to abiotic stress. The comprehension of DNA methylation at promoter region of TaGAPC1 can provide insights into the transcription regulation mechanisms of plant genes under abiotic stress. In this study, we cloned TaGAPC1 genes and its promoters from two wheat genomes, then investigated the expression patterns of TaGAPC1 under osmotic and salinity stress, and analyzed the promoter sequences. Moreover, the methylation patterns of promoters under stress were confirmed. Expression analysis indicated that TaGAPC1 was induced inordinately by stresses in two wheat genotypes with contrasting drought tolerance. Several stress-related cis-acting elements (MBS, DRE, GT1 and LTR et al.) were located in its promoters. Furthermore, the osmotic and salinity stress induced the demethylation of CG and CHG nucleotide in the promoter region of Changwu134. The methylation level of CHG and CHH in promoter of Zhengyin1 was always increased under stresses, and the CG contexts remained unchanged. The cytosine loci of stress-related cis-acting elements also showed different methylation changes in this process. These results provide insights into the relationship between promoter methylation and gene expression, promoting the function investigation of GAPC.

The role and signaling of sphingosine-1-phosphate (S1P) during darkness-induced stomatal closure were examined in Vicia faba. Darkness substantially raised S1P and hydrogen peroxide (H2O2) levels and closed stomata. These darkness effects were significantly suppressed by DL-threo-dihydrosphingosine (DL-threo-DHS) and N,N-dimethylsphingosine (DMS), two inhibitors of long-chain base kinases. Exogenous S1P led to stomatal closure and H2O2 production, and the effects of S1P were largely prevented by the H2O2 modulators ascorbic acid, catalase, and diphenyleneiodonium. These results indicated that S1P mediated darkness-induced stomatal closure by triggering H2O2 production. In addition, DL-threo-DHS and DMS significantly suppressed both darkness-induced cytosolic alkalization in guard cells and stomatal closure. Exogenous S1P caused cytosolic alkalization and stomatal closure, which could be largely abolished by butyric acid. These results demonstrated that S1P synthesis was necessary for cytosolic alkalization during stomatal closure caused by darkness. Furthermore, together with the data described above, inhibition of darkness-induced H2O2 production by butyric acid revealed that S1P synthesis-induced cytosolic alkalization was a prerequisite for H2O2 production during stomatal closure caused by darkness, a conclusion supported by the facts that the pH increase caused by exogenous S1P had a shorter lag and peaked faster than H2O2 levels and that butyric acid prevented exogenous S1P-induced H2O2 production. Altogether, our data suggested that darkness induced S1P synthesis, causing cytosolic alkalization and subsequent H2O2 production, finally leading to stomatal closure.

Fungi are promising materials for soil metal bioextraction and thus biomining. Here, a macrofungi-based system was designed for rapid cadmium (Cd) removal from alkaline soil. The system realized directed and rapid fruiting body development for subsequent biomass harvest. The Cd removal efficiency of the system was tested through a pot culture experiment. It was found that aging of the added Cd occurred rapidly in the alkaline soil upon application. During mushroom growth, the soil solution remained considerably alkaline, though a significant reduction in soil pH was observed in both Cd treatments. Cd and dissolved organic carbon (DOC) in soil solution generally increased over time and a significant correlation between them was detected in both Cd treatments, suggesting that the mushroom‒substratum system has an outstanding ability to mobilize Cd in an alkaline environment. Meanwhile, the growth of the mushrooms was not affected relative to the control. The estimated Cd removal efficiency of the system was up to 12.3% yearly thanks to the rapid growth of the mushroom and Cd enrichment in the removable substratum. Transcriptomic analysis showed that gene expression of the fruiting body presented considerable differences between the Cd treatments and control. Annotation of the differentially expressed genes (DEGs) indicated that cell wall sorption, intracellular binding, and vacuole storage may account for the cellular Cd accumulation. In conclusion, the macrofungi-based technology designed in this study has the potential to become a standalone biotechnology with practical value in soil heavy metal removal, and continuous optimization may make the system useful for biomining.

Pairwise alignments of wheat Glyceraldehyde 3-phosphate dehydrogenase. (PDF 33 kb)

GAPDH family in plants. (PDF 49 kb)

Multiple alignment of wheat GAPDH amino acid sequences. (PDF 462 kb)

Multiple alignment of animal/fungi/plant GAPDH amino acid sequences. (PDF 485 kb)

Multiple alignment of GPAN amino acid sequences. (PDF 345 kb)

HMMsearch hits of wheat Glyceraldehyde 3-phosphate dehydrogenase. (PDF 93 kb)

Motif LOGOs of GAPDHs and GAPNs generated by MEME. (PDF 593 kb)

A study was undertaken to determine the use of a plasmid DNA scission assay to evaluate the causal relationships between particle oxidative capacity and physico-chemistry. Field emission scanning electron microscopy (FESEM), image analysis (IA) and inductively coupled plasma-mass spectrometry (ICP-MS) were employed to investigate the physico-chemical characteristics of indoor PM10 (particulate matter with an aerodynamic diameter of 10 μm or less) in Beijing, China. Six PM10 samples (indoor smoker's living room; indoor non-smoker's living room and kitchen; and outdoor Beijing city; winter versus summer) were selected to represent typical indoor Beijing PM10 environments that contain high particle mass. The PM10 collected from a kitchen and two smoker's homes had the lowest TD50 (toxic dosage of PM10 causing 50% plasmid DNA damage), being as low as 45 μg ml−1 (kitchen) and 100 μg ml−1 (living room), which suggests a high oxidative capacity, with the PM10 generated in kitchens appearing to be the most toxic. The indoor PM10 from the non-smoker's home and outdoor PM10 samples demonstrated high TD50 values and were deemed less bioreactive (i.e. caused limited DNA damage). FESEM observations revealed that four types of particle species were prevalent in Beijing indoor PM10; soot aggregates, minerals, coal fly ash and unknown fine particles. IA showed that higher percentages of soot and unknown fine particles were associated with the lower TD50 values, suggesting that soot and the unknown fine particles may be important components responsible for the observed plasmid DNA damage. The water-soluble trace elements were negatively correlated with the TD50 values, implying that the DNA damage may be attributed to the water-soluble fraction of the PM10. Water-soluble zinc revealed the best relationship with the TD50 values than other analyzed elements, signifying it may play a role in driving the oxidative damage.

Asian dust storm (ADS) samples were collected on March 20, 2002 in Beijing, China. High-resolution field emission scanning electron microscopy with energy dispersive X-ray detector (FESEM-EDX) and X-ray diffraction (XRD) were used to study the morphology, chemical compositions, number-size distributions and mineralogical compositions of ADS particles. The mineral particles were major components in the ADS samples, accounting for 94% by number. The XRD analysis indicated that the dust particles were dominated by clay (40.3%), and quartz (19.5%), followed by plagioclase (8.4%), calcite (7.5%), K-feldspar (1.5%), hematite (0.9%), pyrite (0.9%), hornblende (0.4%) and gypsum (0.3%), with a certain amount of noncrystalline materials (20.3%). Clay minerals were mainly illite/smectite mixed layers (78%), followed by illite (9%), kaolinite (6%), and chlorite (7%). In addition to these main minerals, FESEM-EDX also detected some trace minerals, such as dolomite, pyrite, thenardite, as well as heavy minerals represented by rutile, ilmenite and apatite. The mineralogical compositions of the 2002-03-20 Asian dust storm and the Saharan dust plumes were similar but the clay mineralogy showed a great distinction, with the illite/smectite mixed layers being common in the Asian dust storm but illite being common in the Saharan dust plumes.

Replanting disease is a major factor limiting the artificial cultivation of the traditional Chinese medicinal herb Salvia miltiorrhiza. At present, little information is available regarding the role of miRNAs in response to replanting disease. In this study, two small RNA libraries obtained from first-year (FPR) and second-year plant (SPR) roots were subjected to a high-throughput sequencing method. Bioinformatics analysis revealed that 110 known and 7 novel miRNAs were annotated in the roots of S. miltiorrhiza. Moreover, 39 known and 2 novel miRNAs were identified and validated for differential expression in FPR compared with SPR. Thirty-one of these miRNAs were further analyzed by qRT-PCR, which revealed that 5 miRNAs negatively regulated the expression levels of 7 target genes involved in root development or stress responses. This study not only provides novel insights into the miRNA content of S. miltiorrhiza in response to replanting disease but also demonstrates that 5 miRNAs may be involved in these responses. Interactions among the differentially expressed miRNAs with their targets may form an important component of the molecular basis of replanting disease in S. miltiorrhiza.

Construction of recombinant plasmid vector for gene expression is a key step in making transgenic plants and important to study gene function and plant genetic engineering. A right choice of gene construction method can be cost-effective and achieve more diverse recombinant plasmids. In addition to the traditional methods in construction of plant gene expression vectors, such as Gateway technology, three DNA method and one step cloning, a few novel methods have been developed in recent years. These methods include oligonucleotide synthesis-based construction of small fragment gene expression vectors via competitive connection; construction of small RNA expression vector using pre-microRNA; recombination-fusion PCR method which inserts DNA fragments of multiple restriction sites into the target vector; and insertion of a DNA fragment into any region of a linear vector via In-Fusion Kit. Construction of complex vectors with many fragments uses sequence and ligation-independent cloning method, Gibson isothermal assembly or Golden Gate assembly. This paper summarizes our working experience in the area of recombinant vector construction and reports from others with an intention to disseminate ideas about currently widely used DNA recombination methods for plant transformation.