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The red light (R) to far-red light (FR) ratio (R:FR) regulates plant responses to salt stress, but the regulation mechanism is still unclear. In this study, tomato seedlings were grown under half-strength Hoagland solution with or without 150 mM NaCl at two different R:FR ratios (7.4 and 0.8). The photosynthetic capacity, antioxidant enzyme activities, and the phenotypes at chloroplast ultrastructure and whole plant levels were investigated. The results showed that low R:FR significantly alleviated the damage of tomato seedlings from salt stress. On day 4, 8, and 12 at low R:FR, the maximum photochemical quantum yields (Fv/Fm) of photosystem II (PSII) were increased by 4.53%, 3.89%, and 16.49%, respectively; the net photosynthetic rates (Pn) of leaves were increased by 16.21%, 90.81%, and 118.00%, respectively. Low R:FR enhanced the integrity and stability of the chloroplast structure of salinity-treated plants through maintaining the high activities of antioxidant enzymes and mitigated the degradation rate of photosynthetic pigments caused by reactive oxygen species (ROS) under salt stress. The photosynthesis, antioxidant enzyme-related gene expression, and transcriptome sequencing analysis of tomato seedlings under different treatments were also investigated. Low R:FR promoted the de novo synthesis of D1 protein via triggering psbA expression, and upregulated the transcripts of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) related genes. Meanwhile, the transcriptome analysis confirmed the positive function of low R:FR on enhancing tomato salinity stress tolerance from the regulation of photosynthesis and ROS scavenging systems.

To gain deep insight into the content of inorganic mercury (Hg2+) and organic mercury (OrgHg) in the organisms or environment, speciation analysis was urgently required. The traditional methods for...

A method of cobalt ion assisted enhancement of photochemical vapor generation-atomic fluorescence spectrometry (PVG-AFS) was proposed for sensitive determination of ultratrace tellurium(IV). With a mixture of 5% (v/v) formic acid and 20% (v/v) acetic acid as the reaction medium, more than 13-fold improvement in AFS intensity for Te(IV) was achieved simply by adding 1 mg L−1 Co2+ as a homogeneous catalyst. A possible reaction mechanism was proposed with the characterization results of GC-MS and electron paramagnetic resonance (EPR). Under optimal conditions, the limit of detection (LOD) for Te(IV) was 0.06 μg L−1, with a relative standard deviation (RSD) of 1.3% (10 μg L−1 Te, 7 times). The accuracy and utility of this methodology were validated by analysis of real water samples, with satisfactory recoveries of 91–108%.

Stomatal opening/closure plays a key role in balancing a plant’s need to conserve water, while still allowing for the exchange of photosynthetic and respiratory gasses with the atmosphere. Stomatal opening/closure can be induced by differences in light quality but a detailed knowledge of the role of light in stomatal regulation in tomato is limited. In this study, we evaluated red and blue light-dependent stomatal opening processes in tomato seedlings and explored the mechanisms involved using different light-quality treatments. After 10 h of darkness, tomato seedlings were subjected to the following five treatments: monochromatic red light (R), 33% blue (2R1B), 50% blue (1R1B), 67% blue (1R2B), and monochromatic blue light (B) at 200 μmol m−2s−1light intensity. The highest stomatal conductance recorded were for 1R1B. Stomatal aperture under 1R1B showed a 92.8% increase after 15 min and a 28.6% increase after 30 min compared with under R alone. Meanwhile, the study shows that the expressions of the plasma membrane H+-ATPase in the leaf were regulated by different proportions of blue light. The results show that the expressions of HA1 and HA4 increased under 1R1B and 1R2B after 15 min of exposure compared with under R alone. Under 1R1B, our results also show net photosynthesis increased compared with R and B after longer treatments, which may be related to chloroplast ultrastructure, and leaf dry weight increased compared with under 1R2B or B alone, but there were no differences under the R and 2R1B light treatments.

Carbon dioxide concentration (CO2 ) and light intensity are known to play important roles in plant growth and carbon assimilation. Nevertheless, the underlying physiological mechanisms have not yet been fully explored. Tomato seedlings (Solanum lycopersicum Mill. cv. Jingpeng No. 1) were exposed to two levels of CO2 and three levels of light intensity and the effects on growth, leaf gas exchange and water use efficiency were investigated. Elevated CO2 and increased light intensity promoted growth, dry matter accumulation and pigment concentration and together the seedling health index. Elevated CO2 had no significant effect on leaf nitrogen content but did significantly upregulate Calvin cycle enzyme activity. Increased CO2 and light intensity promoted photosynthesis, both on a leaf-area basis and on a chlorophyll basis. Increased CO2 also increased light-saturated maximum photosynthetic rate, apparent quantum efficiency and carboxylation efficiency and, together with increased light intensity, it raised photosynthetic capacity. However, increased CO2 reduced transpiration and water consumption across different levels of light intensity, thus significantly increasing both leaf-level and plant-level water use efficiency. Among the range of treatments imposed, the combination of increased CO2 (800 µmol CO2 mol-1 ) and high light intensity (400 µmol m-2 s-1 ) resulted in optimal growth and carbon assimilation. We conclude that the combination of increased CO2 and increased light intensity worked synergistically to promote growth, photosynthetic capacity and water use efficiency by upregulation of pigment concentration, Calvin cycle enzyme activity, light energy use and CO2 fixation. Increased CO2 also lowered transpiration and hence water usage.

The development of an efficient and convenient non-enzymatic glucose (Glu) sensor is an extremely attractive and challenging subject. In this work, a 3D cobalt phosphide coated nickel-cobalt layered double hydroxide heteronanosheet array on Ni foam (CoxP@NiCo-LDH NSA/NF) was constructed using electrodeposition and high-temperature phosphating technology. Its unique heteronanosheet array structure and synergistic effect resulting in excellent electrochemical activity for Glu. The response time of the sensor is ultra-fast (

Selenium was taken as an example to investigate the effect of variable ultraviolet (UV) wavelength and intensity on its photochemical vapor generation (photo-CVG) process. A broadband laser-driven light source (LDLS) and a UV lamp were utilized as irradiation sources for the photo-CVG of trace selenium which was sensitively detected by atomic fluorescence spectrometry (AFS). Five filters with bandpass at different wavelength (254 nm, 285 nm, 315 nm, 365 nm and 395 nm) were used to filtrate the light from the LDLS and the UV lamp. The signal change of Se(VI) by photo-CVG-AFS was monitored when a TiO2-coated quartz coil was irradiated by variable wavelength and intensity. The experimental results indicated: (1) the efficiency of Se(VI) photo-CVG varied with irradiation wavelength; (2) a synergistic effect existed for the photo-CVG, and the efficiency of the full spectrum was thus better or close to the sum of all wavelengths; and (3) the efficiency of Se(VI) photo-CVG was also affected by the UV intensity.

A miniaturized UV-LED photochemical reactor is proposed for selenium photochemical vapor generation (Photo-CVG). The miniaturized Photo-CVG reactor with a coin size mainly consists of an ultraviolet light-emitting-diode (UV-LED) and a quartz coil with nano-TiO2 coating on its inner wall. It was coupled with an atomic fluorescence spectrometer (AFS) as a sample introduction device for trace selenium determination. The nano-TiO2 coating process, UV-LED wavelength and correlative experimental parameters as well as potential interference were investigated in detail. Under optimized experimental conditions, limits of detection of 0.21 and 0.28 μg L−1 for Se(VI) and Se(IV) were obtained, respectively, with a relative standard deviation (n = 3) of 2.5% and 1.0% at 20 μg L−1. The potential application of this UV-LED Photo-CVG AFS was demonstrated by successfully analyzing a certified reference water sample and several mineral water samples.

Nano g-C 3 N 4 /TiO 2 composite was synthetized and utilized as a novel photocatalyst for enhanced photochemical vapor generation for sample introduction to atomic fluorescence spectrometry. High reduction efficiency for Se (VI) was obtained to facilitate its ultrasensitive determination by atomic fluorescence spectrometry, with a limit of detection of 0.08 ng mL − 1 . The photocatalytic mechanism of this composite was also discussed and demonstrated its highly efficient photocatalytic capacity and promissing applications in trace selenium (VI) determination and extraction.

To obtain new insights into the mechanisms of the positive effects of exogenous melatonin applications to cucumber seedlings during chilling, we investigated its role in regulating photosynthesis, the transcription level of csZat12 and the metabolism of polyamines (PAs) and of abscisic acid (ABA). The negative effects of chilling were clearly alleviated in cucumber seedlings by irrigation with 200 μM melatonin solution. This was evidenced by alleviation of the decline in net photosynthesis rate and also in electrolyte leakage in chilled plants. The reasons for this can be explained as follows. First, melatonin up-regulates CsZat12, an important stress-related gene. Second, melatonin increases the content of putrescine (Put) and spermidine (Spd) and stabilized spermine (Spm) by altering the activity of the PA metabolic enzymes. And, third, ABA is also involved in these effects as melatonin modulated the expression of the key ABA biosynthesis genes (CsNCED1 and CsNCED2) and also the key ABA catabolism genes (CsCYP707A1 and CsCYP707A2). This study provides new evidence suggesting melatonin mitigates chilling stress in cucumber by up-regulating the expression of CsZat12 and by modulating the metabolism of PAs and ABA.

Inductively coupled plasma (ICP) is one of the most popular sources in analytical atomic spectrometers, including inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES). There are several unique independent advantages for either of them. Therefore, a simultaneous elemental analysis system was established for synergetic work of ICP-MS and ICP-OES by sharing one ICP to improve the analytical figures of merit. To demonstrate its unique utility, several special applications were studied, including correction of interferences for each other, synergetic determination for accurate analysis and combinatorial analysis for larger linear ranges of calibration curves.

Salinity-alkalinity stress has caused severe environment problems that negatively impact the growth and development of watermelon (Citrullus lanatus L.). In this study, watermelon seedlings were inoculated with the arbuscular mycorrhizal fungi (AMF) Funneliformis mosseae to investigate its effect on watermelon growth and development. The main measurements included morphological traits, elemental and water uptake, the level of reactive oxygen species, antioxidant enzyme and photosynthesis activities, and relative expression levels of stress response genes. Under salinity-alkalinity stresses, watermelon morphological traits, elemental and water uptake were all significantly alleviated after incubation with AMF. Antioxidant abilities of watermelon were significantly improved after incubation with AMF in salinity-alkalinity stresses. Under normal conditions, all photosynthesis related parameters were significantly increased after incubation of AMF. In contrast, they were all significantly reduced under salinity-alkalinity stresses and were all significantly alleviated after incubation of AMF. Salinity-alkalinity stresses impacted the chloroplast structure and AMF significantly alleviated these damages. Under salinity-alkalinity stresses, the relative expression level of RBCL was significantly reduced and was significantly alleviated after AMF treatment. The relative expression level of PPH was significantly increased and was further significantly reduced after AMF treatment. For the relative expression levels of antioxidant response related genes Cu-Zn SOD, CAT, APX, GR, their relative expression levels were significantly increased and were further significantly increased after AMF treatment. Our study demonstrated the beneficial effects of AMF under salinity-alkalinity stresses, which could be implicated in the management of watermelon cultivation under salinity-alkalinity regions.

Flame synthesis is one of the important methods for the synthesis of nanomaterials. In this work, NiO nanoparticles on carbon cloth (NiO/CC) were synthesized via a flame method, and the synthesized NiO/CC was used as a non-enzymatic sensor for the detection of glucose and formaldehyde. NiO/CC shows an excellent analytical performance for glucose sensing with a satisfactory reproducibility and selectivity, providing a response time as short as 3 s, a wide detection ranging from 5 μM to 2 mM, a LOD with 7.45 nM (S/N = 3), and a sensitive response with 4025 μA mM−1cm−2. Furthermore, the sensor also has a sensitive response to formaldehyde, a LOD of 6.8 nM (S/N = 3), a sensitivity of 5752 μA mM−1cm−2 and a response time of 3 s were obtained.

The NiCl(OH) nanosheet array grown in situ on the carbon cloth (NiCl(OH) NS/CC) was synthesized using only anhydrous ethanol and NiCl2·6H2O as a raw material in a mild hydrothermal method. In this paper, NiCl(OH) NS/CC was used as the working electrode for electrochemically sensing glucose under alkaline conditions. Compared with some reports of nickel-based electrochemical detection of glucose, the NiCl(OH) NS/CC electrochemical sensor demonstrates a high sensitivity of 8052.0 μA mM−1 cm−2, a wide linear range of 0.001–3.45 mM, a lower detection limit of 0.29 μM and a response time of less than 5 s. In addition, our sensors can effectively detect glucose in serum and saliva of human beings. Furthermore, the NiCl(OH) NS/CC catalyst has good long-term stability and is highly selective for glucose detection.

In this work, magnetic Fe3O4@ZIF-8 core-shell nanoparticles (MNPs) were employed for effective adsorption of inorganic arsenic for preconcentration, with adsorption mechanism thoroughly discussed. The adsorbed inorganic arsenic was easily separated by a magnet along with the MNPs from the sample matrix, with possible matrix interference eliminated. The MNPs were then completely dissolved in hydrochloric acid prior to the determination of inorganic arsenic by hydride generation-atomic fluorescence spectrometry. The Fe3O4@ZIF-8 MNPs were prepared with a facile step-by-step assembly method in aqueous solution at room temperature. Under the optimized conditions, the sensitivity for inorganic arsenic determination was significantly increased through preconcentration, with satisfactory analytical merits obtained.

Polyamines are important in protecting plants against various environmental stresses, including protection against photodamage to the photosynthetic apparatus. The molecular mechanism of this latter effect is not completely understood. Here, we have investigated the effects of salinity-alkalinity stress and spermidine (Spd) on tomato seedlings at both physiological and transcriptional levels. Salinity-alkalinity stress decreased leaf area, net photosynthetic rate, maximum net photosynthetic rate, light saturation point, apparent quantum efficiency, total chlorophyll, chlorophyll a and chlorophyll a:chlorophyll b relative to the control. The amount of D1 protein, an important component of photosystem II, was reduced compared with the control, as was the expression of psbA, which codes for D1. Expression of the chlorophyll biosynthesis gene porphobilinogen deaminase (PBGD) was reduced following salinity-alkalinity stress, whereas the expression of Chlase, which codes for chlorophyllase, was increased. These negative physiological effects of salinity-alkalinity stress were alleviated by exogenous Spd. Expression of PBGD and psbA were enhanced, whereas the expression of Chlase was reduced, when exogenous Spd was included in the stress treatment compared with when it was not. The protective effect of Spd on chlorophyll and D1 protein content during stress may maintain the photosynthetic apparatus, permitting continued photosynthesis and growth of tomato seedlings (Solanum lycopersicum cv. Jinpengchaoguan) under salinity-alkalinity stress.

Selenium was the first reported element that could be converted into its volatile compounds via photochemical vapor generation (photo-CVG) process before its atomic spectrometric detection. Photo-CVG is a newly emerging vapor generation technique, offering its inherent advantages of matrix interferences eliminated and high vapor efficiency etc., photo-CVG has been combined with various methods for selenium determination and mechanism exploration. Herein, we summarize the development of selenium in photo-CVG from the first report in 2003, the mechanisms of selenium with or without TiO2 were discussed and its applications for selenium determination, speciation analysis and prereduction were summarized.

In this paper, we developed a method of one-step synthesis of Co(OH)F nanoflower on carbon cloth (Co(OH)F NF/CC) by dielectric barrier discharge microplasma as a highly efficient catalytic electrode for sensing glucose under alkaline conditions. Thanks to the microplasma-based synthesis method, only 1.5 h the Co(OH)F nanoflower obtained in situ on the carbon cloth under ambient temperature and pressure. As a non-enzymatic sensor, the Co(OH)F NF/CC electrode exhibited good electrocatalytic activity, such as shorter response time (

Background Red (R) and far-red (FR) light distinctly influence phytochrome-mediated initial tomato growth and development, and more recent evidence indicates that these spectra also modulate responses to a multitude of abiotic and biotic stresses. This research investigated whether different R: FR values affect tomato growth response and salinity tolerance. Tomato seedlings were exposed to different R: FR conditions (7.4, 1.2 and 0.8) under salinity stress (100 mM NaCl), and evaluated for their growth, biochemical changes, active reactive oxygen species (ROS) and ROS scavenging enzymes, pigments, rate of photosynthesis, and chlorophyll fluorescence. Results The results showed that under conditions of salinity, tomato seedlings subjected to a lower R: FR value (0.8) significantly increased both their growth, proline content, chlorophyll content and net photosynthesis rate (Pn), while they decreased malondialdehyde (MDA) compared to the higher R: FR value (7.4). Under conditions of salinity, the lower R: FR value caused a decrease in both the superoxide anion (O2 •−) and in hydrogen peroxide (H2O2) generation, an increase in the activities of superoxidase dismutase (SOD, EC 1.15.1.1), peroxidase (POD, EC 1.11.1.7) and catalase (CAT, EC 1.11.1.7). Tomato seedlings grown under the lower R: FR value and conditions of salinity showed a higher actual quantum yield of photosynthesis (ΦPSII), electron transport rate (ETR), and photochemical quenching (qP) than those exposed to a higher R: FR, indicating overall healthier growth. However, the salinity tolerance induced at the lower R: FR condition disappeared in the tomato phyB1 mutant. Conlusion These results suggest that growing tomato with a lower R: FR value could improve seedlings’ salinity tolerance, and phytochrome B1 play an very important role in this process. Therefore, different qualities of light can be used to efficiently develop abiotic stress tolerance in tomato cultivation.

Cadmium ion-enhanced photochemical vapour generation directly from Se(vi) has for the first time been reported here, and the key mechanism of the in situ formation of nano-CdSe as a photocatalyst has been revealed.

Brassinosteroids (Brs) are a newly recognized group of active steroidal hormones that occur at low concentrations in all plant parts and one of the active and stable forms is 24-epibrassinolide (EBR). We investigated the effect of EBR on tomato (Lycopersicon esculentum Mill.) and its mechanism when seedlings were exposed to low temperature and poor light stress conditions. Leaves of stress-tolerant 'Zhongza9' and stress-sensitive 'Zhongshu4' cultivars were pre-treated with spray solutions containing either 0.1 μM EBR or no EBR (control). The plants were then transferred to chambers where they were exposed to low temperatures of 12 °C/6 °C (day/night) under a low light (LL) level of 80 μmol · m(-2) · s(-1). Exogenous application of EBR significantly increased the antioxidant activity of superoxide dismutase, catalase and peroxidase, and decreased the rate of O2 · (-) formation and H2O2 and malondialdehyde contents. Additionally, the ATP synthase β subunit content was increased by exogenous hormone application. Based on these results, we conclude that exogenous EBR can elicit synergism between the antioxidant enzyme systems and the ATP synthase β subunit so that scavenging of reactive oxygen species becomes more efficient. These activities enable plants to cope better under combined low temperature and poor light stresses.

In this research, the protective effect of spermidine (Spd) in mitigating saline-alkaline stress in tomato (Solanum lycopersicum L.) at physiological and proteomic levels were examined. The results showed that saline-alkaline stress induced accumulation of H2O2 and O2(-*), and increased the activities of antioxidase (SOD, CAT, and POD). Spermidine efficiently alleviated the inhibitory role of saline-alkaline on plant growth and inhibited saline-alkaline stress-induced H2O2 and O2(-*) accumulation. Proteomics investigations of the leaves of tomato seedlings, responding to a 75 mM saline-alkaline solution and 0.25 mM Spd, were performed. Maps of the proteome of leaf extracts were obtained by two-dimensional gel electrophoresis. An average of 49, 47 and 34 spots, which appeared repeatedly and that significantly altered the relative amounts of polypeptides by more than twofold, were detected for seedlings treated with saline-alkaline solution (S) compared to normal solution (CK), saline-alkaline plus spermidine (MS) compared to CK, or S versus MS, respectively. Thirty-nine of these proteins were identified by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry and were classified into five functional categories, including energy and metabolism, signal transduction, amino acid metabolism, protein metabolism, and stress-defense response. Proteomics analysis coupled with bioinformatics indicated that Spd treatment helps tomato seedlings combat saline-alkaline stress by modulating the defense mechanism of plants and activating cellular detoxification, which protect plants from oxidative damage induced by saline-alkaline stress.

Atomic fluorescence spectrometry (AFS), as one of the common atomic spectrometric techniques with high sensitivity, simple instrumentation, and low acquisition and running cost, has been widely used in various fields for trace elemental analysis, notably the determination of hydride-forming elements by hydride generation atomic fluorescence spectrometry (HG-AFS). In recent years, the soaring demand of field analysis has significantly promoted the miniaturization of analytical atomic spectrometers or at least instrumental components. Various techniques have also been developed to approach the goal of portable/miniaturized AFS instrumentation for field analysis. In this review, potentially portable/miniaturized AFS techniques, primarily involving advanced instrumental components and whole instrumentation with references since 2000, are summarized and discussed. The discussion mainly includes five aspects: radiation source, atomizer, detector, sample introduction, and miniaturized atomic fluorescence spectrometer/system.

The healing of chronic wounds remains a considerable challenge in clinical trials and imposes severe financial and physiological burdens on patients. Many works are being tried to find ideal clinical promoting wound healing biomaterials. Small bioactive peptides with low cost and easy production, store and transfer become excellent candidates. Here, we identified a novel peptide (named OM-LV20) from skin secretions of odorous frog Odorrana margaretae. The peptide had an amino acid sequence of "LVGKLLKGAVGDVCGLLPIC," contained an intramolecular disulfide bridge at the C-terminus, and was produced by post-translational processing of a 71-residue prepropeptide. Our results showed that OM-LV20 had no direct microbe-killing effects, hemolytic activity, or acute toxicity, but did exhibit weak antioxidant activity. OM-LV20 promoted wound healing against human keratinocytes (HaCaT) and human skin fibroblasts (HSF) in both time- and dose-dependent manners. In addition, it induced the proliferation of HaCaT but not HSF cells. Of note, OM-LV20 showed strong wound healing-promoting activity in a mice model of full-thickness skin wound. Our research indicates the cellular and animal level wound healing potential of OM-LV20, and thus provides a novel bioactive peptide template for the development of wound healing agents and medicine.

The aim of the study was to monitor the effects of exogenous melatonin on cucumber (Cucumis sativus L.) chloroplasts and explore the mechanisms through which it mitigates chilling stress. Under chilling stress, chloroplast structure was seriously damaged as a result of over-accumulation of reactive oxygen species (ROS), as evidenced by the high levels of superoxide anion (O2-) and hydrogen peroxide (H2O2). However, pretreatment with 200 μM melatonin effectively mitigated this by suppressing the levels of ROS in chloroplasts. On the one hand, melatonin enhanced the scavenging ability of ROS by stimulating the ascorbate–glutathione (AsA-GSH) cycle in chloroplasts. The application of melatonin led to high levels of AsA and GSH, and increased the activity of total superoxide dismutase (SOD, EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11), monodehydroascorbate reductase (MDHAR, EC 1.6.5.4) dehydroascorbate reductase (DHAR, EC 1.5.5.1), glutathione reductase (GR, EC1.6.4.2) in the AsA-GSH cycle. On the other hand, melatonin lessened the production of ROS in chloroplasts by balancing the distribution of photosynthetic electron flux. Melatonin helped maintain a high level of electron flux in the PCR cycle [Je(PCR)] and in the PCO cycle [Je(PCO)], and suppressed the O2-dependent alternative electron flux Ja(O2-dependent) which is one important ROS source. Results indicate that melatonin increased the chilling tolerance of chloroplast in cucumber seedlings by accelerating the AsA-GSH cycle to enhance ROS scavenging ability and by balancing the distribution of photosynthetic electron flux so as to suppress ROS production.

Excess nitrate stress has become a threat of environmental issues to crop cultivation in China. While measures of remediation and knowledge of the mechanisms underlying excess nitrate stress are limited. Previous studies reported that melatonin could improve the plant resistance to abiotic stress. Thus, we investigated the role of melatonin on the photosynthetic characteristic involved in nitrate assimilation under the excess nitrate stress in lettuce (Lactuca sativa ). Lettuce plants were subjected to moderate excess nitrate stress (160 mM NO3 −) with/without supply of 1.0 μM melatonin. Results showed that adding of melatonin decreased the nitrate content both in leaves and roots. Melatonin also dramatically increased the fresh and dry weights in lettuce seedlings. According to the chlorophyll fluorescence parameters, exogenous melatonin inhibited the reduction inPSII, Fv'/Fm', qP and rETR caused by excess nitrate stress, while reduced NPQ. In conclusion, exogenous melatonin could decrease the nitrate content in lettuce tissues and enhance the activity of PSII as well as the light energy conversion efficiency for carbon assimilation.

We studied the effects of exogenous spermidine (Spd) on plant growth and nitrogen metabolism in two cultivars of tomato (Solanum lycopersicum) that have differential sensitivity to mixed salinity-alkalinity stress: ‘Jinpeng Chaoguan’ (salt-tolerant) and ‘Zhongza No. 9’ (salt-sensitive). Seedling growth of both tomato cultivars was inhibited by salinity-alkalinity stress, but Spd treatment alleviated the growth reduction to some extent, especially in ‘Zhongza No. 9’. Exogenous Spd may help reduce stress-induced increases in free amino acids, ammonium (NH4+) contents, and NADH-dependent glutamate dehydrogenase (NADH-GDH) activities; depress stress-induced decreases in soluble protein and nitrate content; and depress nitrate reductase, nitrite reductase, glutamine synthetase (GS), NADH-dependent glutamate synthase (NADH-GOGAT), glutamate oxaloacetate transaminase (GOT), and glutamate pyruvate transaminase (GPT) activities, especially for ‘Zhongza No. 9’. Based on our results, we suggest that exogenous Spd promotes the assimilation of excess toxic NH4+ by coordinating and strengthening the synergistic action of NADH-GDH, GS/NADH-GOGAT, and transamination pathways, all during saline-alkaline stress. Subsequently, NH4+ and its related enzymes (GDH, GS, GOGAT, GOT, and GPT), in vivo, are maintained in a proper and balanced state to enable mitigation of stress-resulted damages. These results suggest that exogenous Spd treatment can relieve nitrogen metabolic disturbances caused by salinity-alkalinity stress and eventually promote plant growth.

The developing cerebellum is extremely vulnerable to hypoxia which can damage the Purkinje neurons. We hypothesized that this might be mediated by tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) derived from activated microglia as in other brain areas. One-day-old rats were subjected to hypoxia following, which the expression changes of various proteins in the cerebellum including hypoxia inducible factor-1α, TNF-α, IL-1β, TNF-R1 and IL-1R1 were analyzed. Following hypoxic exposure, TNF-α and IL-1β immunoexpression in microglia was enhanced coupled by that of TNF-R1 and IL-1R1 in the Purkinje neurons. Along with this, hypoxic microglia in vitro showed enhanced release of TNF-α and IL-1β whose receptor expression was concomitantly increased in the Purkinje neurons. In addition, nitric oxide (NO) level was significantly increased in the cerebellum and cultured microglia subjected to hypoxic exposure. Moreover, cultured Purkinje neurons treated with conditioned medium derived from hypoxic microglia underwent apoptosis but the incidence was significantly reduced when the cells were treated with the same medium that was neutralized with TNF-α/IL-1β antibody. We conclude that hypoxic microglia in the neonatal cerebellum produce increased amounts of NO, TNF-α and IL-1β which when acting via their respective receptors could induce Purkinje neuron death.

Association mapping has been widely used to map the significant associated loci responsible for natural variation in complex traits and are valuable for crop improvement. Sugars and organic acids are the most important metabolites in tomato fruits. We used a collection of 174 tomato accessions composed of Solanum lycopersicum (123 accessions) and S. lycopersicum var cerasiforme (51 accessions) to detect significantly associated loci controlling the variation of main sugars and organic acids. The accessions were genotyped with 182 SSRs spreading over the tomato genome. Association mapping was conducted on the main sugars and organic acids detected by gas chromatography-mass spectrometer (GC-MS) over 2 years using the mixed linear model (MLM). We detected a total of 58 significantly associated loci (P < 0.001) for the 17 sugars and organic acids, including fructose, glucose, sucrose, citric acid, malic acid. These results not only co-localized with several reported QTLs, including fru9.1/PV, suc9.1/PV, ca2.1/HS, ca3.1/PV, ca4.1/PV, and ca8.1/PV, but also provided a list of candidate significantly associated loci to be functionally validated. These significantly associated loci could be used for deciphering the genetic architecture of tomato fruit sugars and organic acids and for tomato quality breeding.

The roots of Salvia miltiorrhiza Bunge are widely used in traditional Chinese medicine. The objective of this study was to investigate the effect of drought stress on growth and active constituents composition in S. miltiorrhiza. Three water-stress treatments, including control, medium drought stress and severe drought stress, were applied on the whole growth cycle. The results showed that drought stress significantly decreased both shoot and root dry weight in S. miltiorrhiza, but increased the root to shoot ratio at later growth cycle. Except rosmarinic acid the other active constituents content increased under water-stress conditions. Water stress significantly increased salvianolic acid B yield, and decreased that of tanshinone IIA. Our study suggests that it might be feasible to improve or develop S. miltiorrhiza cultivation methods under semi-arid and arid regions. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.

Five different doses of ultraviolet-B (UV-B) radiation were supplied to tomato (Lycopersicon esculeutum. Mill) with the doubled CO2 concentration (700 μmol · mol−1) in the winter plastic greenhouse. The influences on the seedling growth, fruit quality and yield of tomato were investigated. Results showed that the seedling growth, and the contents of UV absorbing compounds, soluble sugar, organic acid, vitamin C and lycopene of tomato fruits, and yield of tomato increased under doubled CO2 concentration. Under the doubled CO2 concentration the effects of lost doses of UV-B radiation could further promote the effects of doubled CO2 concentration. However, there is no significant increase in yield of tomato. The best dose of UV-B radiation is about 1.163 kJ·m−2. When the dose of UV-B radiation is more than it, the effects of UV-B will be reduced.

Symbiosis with root-associated arbuscular mycorrhizal fungi (AMF) can improve plant phosphorus (P) uptake and alleviate environmental stresses. It could be also an effective mean to promote plant performance under low temperatures. The combined effects of arbuscular mycorrhiza and low temperature (15°C/10°C day/night) on cucumber seedlings were investigated in the present study. Root colonisation by AMF, succinate dehydrogenase and alkaline phosphatase activity in the intraradical fungal structures, plant growth parameters, and expression profiles of four cucumber phosphate (Pi) transporters, the fungal Pi transporter GintPT and alkaline phosphatase GintALP were determined. Cold stress reduced plant growth and mycorrhizal colonisation. Inoculation improved cucumber growth under ambient temperatures, whereas under cold stress only root biomass was significantly increased by inoculation. AMF supplied P to the host plant under ambient temperatures and cold stress, as evidenced by the higher P content of mycorrhizal plants compared with non-mycorrhizal plants. Thus, the cold-stressed cucumber seedlings still benefited from mycorrhiza, although the benefit was less than that under ambient temperatures. In accordance with this, a cucumber Pi transporter gene belonging to the Pht1 gene family was strongly induced by mycorrhiza at ambient temperature and to a lesser extent under cold stress. The other three Pi transporters tested from different families were most highly expressed in cold-stressed mycorrhizal plants, suggesting a complex interactive effect of mycorrhiza and cold stress on internal P cycling in cucumber plants.

We investigated the effects of seeds pretreatment with exogenous spermidine (Spd) on the polyamine content and metabolism in the roots of two cultivars of tomato (Solanum lycopersicum), Jinpengchaoguan and Zhongza No. 9 grown under conditions of mixed salinity-alkalinity stress. These cultivars differ in their tolerance to salinity stress, with the former more tolerant than the latter. PA content, whether in its free forms, soluble conjugated forms, or insoluble bound forms, increased significantly during salinity-alkalinity stress. The activities of S-adenosylmethionine decarboxylase (SAMDC) and diamine oxidase (DAO), concentrations of free Spd, soluble conjugated forms of Spd and spermine (Spm), and insoluble bound form of Spd in the roots were enhanced to a greater extent in cv. Jinpengchaoguan roots than in cv. Zhongza No.9 in response to salinity-alkalinity stress. Interestingly, Spd application to seeds markedly suppressed the accumulation of free Put, but promoted an increase in free Spd and Spm concentrations, as well as soluble conjugated forms of Spd and insoluble bound forms of Put in both cultivars. From these data, we deduced that exogenous Spd promotes the conversion of free Put into free Spd and Spm, and soluble conjugated forms and insoluble bound forms of PAs under salinity-alkalinity stress. Furthermore, under salinity-alkalinity stress conditions, exogenous Spd enhanced the activities of ODC, SAMDC and DAO, and reduced the activities of ADC and polyamine oxidase (PAO) in cv. Zhongza No.9 roots. In addition, exogenous Spd reduced the activities of ADC and ODC, and increased the activities of DAO and SAMDC in cv. Jinpengchaoguan roots under salinity-alkalinity stress conditions. These results suggest that exogenous Spd treatment can regulate the metabolic status of polyamines caused by salinity-alkalinity stress, and eventually enhance tolerance of tomato plants to salinity-alkalinity stress. Additionally, Spd treatments have varying effects on different tolerant tomato cultivars.

It has been reported that phospholipase C-gamma1 (PLC-gamma1) plays an important protective role in hydrogen peroxide (H(2)O(2))-induced pheochromocytoma (PC) 12 cells death. However, most studies have used high doses of H2O2 and the downstream targets of PLC-gamma1 activation remain to be identified. The present study was designed to examine the roles of PLC-gamma1 signaling pathway in the apoptosis of PC12 cells induced by low dose of H(2)O(2), as well as the downstream factors involved in this pathway. Low-dose treatment of H(2)O(2) resulted in PLC-gamma1 tyrosine phosphorylation in a time-dependent manner and H(2)O(2) killed the PC12 cells by inducing necrosis. In contrast, pretreatment of PC12 cells with U73122, a specific inhibitor of PLC, markedly increased the percentage of dead cells. The mode of cell death was converted to apoptosis as determined by Hoechst/PI nuclear staining and fluorescence microscopy. Western blot analysis demonstrated that the expression of Bcl-2 protein and the activation of pro-caspase-3 were not significantly affected by low dose of H(2)O(2) alone. However, after pretreatment with U73122, Bcl-2 protein expression was dramatically decreased and the activation of pro-caspase-3 was significantly increased. We concluded that PLC-gamma1 plays an important protective role in H(2)O(2)-induced PC12 cells death. Bcl-2 and caspase-3 probably participate in the signaling pathway as downstream factors.

Polyamines are small, ubiquitous, nitrogenous compounds that scavenge reactive oxygen species and stabilize the structure and function of the photosynthetic apparatus in response to abiotic stresses. Molecular details underlying polyamine-mediated photoprotective mechanisms are not completely resolved. This study investigated the role of spermidine (Spd) in the structure and function of the photosynthetic apparatus. Tomato seedlings were subjected to salinity-alkalinity stress with and without foliar application of Spd, and photosynthetic and morphological parameters were analyzed. Leaf dry weight and net photosynthetic rate were reduced by salinity-alkalinity stress. Salinity-alkalinity stress reduced photochemical quenching parameters, including maximum photochemistry efficiency of photosystem II, quantum yield of linear electron flux, and coefficient of photochemical quenching (qP). Salinity-alkalinity stress elevated nonphotochemical quenching parameters, including the de-epoxidation state of the xanthophyll cycle and nonphotochemical quenching (NPQ). Microscopic analysis revealed that salinity-alkalinity stress disrupted the internal lamellar system of granal and stromal thylakoids. Exogenous Spd alleviated the stress-induced reduction of leaf dry weight, net photosynthetic rate, and qP parameters. The NPQ parameters increased by salinity-alkalinity stress were also alleviated by Spd. Seedlings treated with exogenous Spd had higher zeaxanthin (Z) contents than those without Spd under salinity-alkalinity stress. The chloroplast ultrastructure had a more ordered arrangement in seedlings treated with exogenous Spd than in those without Spd under salinity-alkalinity stress. These results indicate that exogenous Spd can alleviate the growth inhibition and thylakoid membrane photodamage caused by salinity-alkalinity stress. The Spd-induced accumulation of Z also may have an important role in stabilizing the photosynthetic apparatus.