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In the southeast of the Qinghai–Tibetan Plateau of China, dragon spruce (Picea asperata) is a key species and widely used in reforestation processes in the area. The paper mainly studied the effects of ultraviolet-B (UV-B) on growth, physiology and nitrogen nutrition of 3- and 6-year-old dragon spruce seedlings. The experimental design included ambient UV-B (control) and enhanced UV-B (+UV-B, a 30% increase). Enhanced UV-B significantly decreased growth, needle and root nitrogen concentration, needle nitrate reductase activity and increased UV-B absorbing compounds and malondialdehyde (MDA) content of two old dragon spruce seedlings. Glutamine synthetase activity was not affected by enhanced UV-B in two old dragon spruce seedlings. On the other hand, different old seedlings also exhibited different physiological responses to enhanced UV-B radiation. Chlorophyll content, carotenoids content and soluble protein content in 3-year-old seedlings significantly reduced by enhanced UV-B, but those in 6-year-old seedlings were not affected by enhanced UV-B. Proline content of 6-year-old seedlings were increased by enhanced UV-B. Compared with the 3-year-old seedlings, the 6-year-old seedlings showed lower reduction of growth and MDA content, and accumulated more proline and UV-B absorbing compounds for protecting seedlings under enhanced UV-B. The results implicated that 3-year-old seedlings were more sensitivity to enhanced UV-B than 6-year-old seedlings.
Atmospheric ozone remains depleted which in turn leads to the increase of UV-B radiation reaching the surface of the earth and in the same time more and more nitrogen will be imported into the terrestrial ecosystems through nitrogen deposition. These two factors will operate simultaneously. The photosynthetic and physiological responses of deciduous broad leaved species Swida hemsleyi occurring commonly at 1350–3700 m a.s.l. subjected to enhanced UV-B and to nitrogen supply were studied. The experimental design included two levels of UV-B treatments (ambient UV-B, 11.02 KJ m⁻² day⁻¹ and enhanced UV-B, 14.33 KJ m⁻² day⁻¹) and two nitrogen levels (without supplemental nitrogen supply and with supplemental nitrogen supply). An experiment was conducted in open semi-field condition in Maoxian Ecological Station of Chinese Academy of Sciences, Sichuan province, China at 1820 m a.s.l. Enhanced UV-B caused a marked decline in growth parameters, net photosynthetic rate, stomatal conductance to water vapour, chlorophyll pigments, whereas it induced an increase in rate of reactive oxygen species (ROS) production and ROS accumulation and malondialdehyde (MDA) content. Enhanced UV-B also induced an increase in leaf thickness and antioxidant compounds content, such as carotenoids and proline content. On the other hand, nitrogen supply caused an increase in some growth parameters, chlorophyll pigments and antioxidant compounds, and reduced ROS accumulation. However, nitrogen supply did not affect MDA content under enhanced UV-B, though it increased antioxidant compounds content and reduced the rate of ROS production and ROS accumulation. These results implied that enhanced UV-B brought harmful effects on Swida hemsleyi seedlings and supplemental nitrogen supply could alleviate the adverse effects of UV-B radiation on plants to some extent.
The paper mainly studied the short-term influences of experimental warming, nitrogen addition, and their combination on physiological performance of P. tabulaeformis seedlings. Free air temperature increase system of infrared heaters was used to raise monthly average soil and air temperature by 2.6 and 2.1 °C above the ambient. NH₄NO₃ solution was added for a total equivalent to 25 g N m⁻² a⁻¹. Experimental warming and nitrogen addition induced a significant increase in leaf nitrogen concentration, Amax, Φ, antioxidant enzymes activities, ASA and free proline contents, but both of them sharply decreased AOS and MDA level. Interestingly, the interaction of warming and nitrogen fertilization further improved leaf nitrogen concentration, Amax, Φ, and antioxidant compounds accumulation, and also resulted in lower rate of O₂⁻ production than either single warming or fertilization. Obviously, the beneficial effects of warming and N fertilization alone on leaf physiology of P. tabulaeformis seedlings were magnified by the combination.
Abies faxoniana is a key species in reforestation processes in the southeast of the Qinghai-Tibetan Plateau of China. The changes in growth, photosynthesis and nutrient status of A. faxoniana seedlings exposed to enhanced ultraviolet-B (UV-B), nitrogen supply and their combination were investigated. The experimental design included two levels of UV-B treatments (ambient UV-B, 11.02 KJ m⁻² day⁻¹; enhanced UV-B, 14.33 KJ m⁻² day⁻¹) and two nitrogen levels (0; 20 g N m⁻²). The results indicated that: (1) enhanced UV-B significantly caused a marked decline in growth parameters, net photosynthetic rate (Pn), photosynthetic pigments and Fv/Fm, (2) supplemental nitrogen supply increased the accumulation of total biomass, Pn, photosynthetic pigments and Fv/Fm under ambient UV-B, whereas supplemental nitrogen supply reduced Pn, and not affect biomass under enhanced UV-B, (3) enhanced UV-B or nitrogen supply changed the concentration of nutrient elements of various organs.
Being one of the largest families of transcriptional regulators in plants, WRKY transcription factors (TFs) have been suggested to play significant roles in regulation of various abiotic and biotic stress responses and several developmental and physiological processes. Modification and analyses of its expression patterns contribute to the elaboration of the complex signaling pathways and regulatory networks. Here, we describe the role of a WRKY TF (MdWRKY13) from apple (Malus domestica) in transgenic Arabidopsis thaliana. Overexpression of this gene in Arabidopsis resulted in drought tolerance decrease when compared to wild type plants. This result indicated that MdWRKY13 seems to be a negative regulator in drought stress response.
In order to evaluate the effects of different slope lengths (1, 2, 3, 4, and 5 m) and different vegetation coverage ratios (20%, 45%, 60%, and 90%) on the mechanisms of nutrient loss and runoff producing processes, we have conducted 14 simulated rainfall experiments. The results show that N and P loss are decided by the concentration and the runoff volume, but when the amounts of N and P in topsoil are small, their loss content mostly depends on runoff volume. Dissolved nitrogen is the main form in the nitrogen loss, while nitrate nitrogen is the main component in dissolved nitrogen, but the proportion in the total nitrogen gradually decreases with slope length increasing or with the increase of vegetation cover; the main form of phosphorus losses is particulate phosphorus, and the excessive sediment-bound nutrient loss released into water might cause secondary pollution of an aquatic environment.
Potato dry matter was isolated from three cultivars of potato tubers at different times during growth. The physicochemical properties of these potato dry matters were characterized for starch and protein content, thermal properties by differential scanning calorimtery (DSC) and paste properties by rapid viscosity analysis (RVA). Dry matter content of potato tubers increased to the highest level and then decreased as growth processed. Superior cultivar potato had a lowest dry matter content and the highest protein content as compared to Snowden and Shepody potatoes. Gelatinization enthalpy and temperature of dry matter varied with growth times and potato cultivars. Immature potato tubers (the earliest harvest) resulted in the highest temperatures for gelatinization, pasting and retrogradation of dry matter, indicating the molecular structure of starch plays an important role in the functional properties of potato dry matter. The quality of table and processing potato could be affected by growth times and cultivars.
Static and stirred culture systems are widely used to expand hematopoietic cells, but differential culture performances are observed between these systems. We hypothesize that these differential culture outcomes are caused by the physiological responses of CD34+ hematopoietic stem and progenitor cells (HSPCs) to the different physical microenvironments created in these culture devices. To understand the genetic changes provoked by culture microenvironments, the gene expression profiling of CD34+ HSPCs grown in static and stirred culture systems was compared using SMART-PCR and cDNA arrays. The results revealed that 103 and 99 genes were significantly expressed in CD34+ cells from static and stirred systems, respectively. Of those, 91 have similar levels of expression, while 12 show differential transcription levels. These differentially expressed genes are mainly involved in anti-oxidation, DNA repair, apoptosis, and chemotactic activity. A quantitative molecular understanding of the influences of growth microenvironments on transcriptional events in CD34+ HSPCs should give new insights into optimizing culture strategies to produce hematopoietic cells.
Plant-specific NAM, ATAF1/2, and CUC (NAC) transcription factors serve essential functions in plant development and plant responses to environmental cues. Yet, transcription factors specific to the rose (Rosa hybrida) NAM/CUC3 subfamily are poorly understood. Here, we identify a novel NAM/CUC3-subfamily transcription factor, RhNAC31, that is associated with flower opening and can be induced by increased salt, cold, and dehydration stress treatment. RhNAC31 has a transactivation region in its C-terminal region, and its overexpression is associated with enhanced cold tolerance in Arabidopsis, conferring a higher survival rate and reduced reactive oxygen (H₂O₂ and O₂⁻) levels. Under salt stress conditions, plants overexpressing RhNAC31 displayed increased germination rates and lower levels of H₂O₂, malondiadehyde (MDA), peroxidase (POD), and superoxide dismutase (SOD). Moreover, RhNAC31 conferred enhanced drought resistance by reducing the rate of water loss through leaves. Further characterization revealed a higher sensitivity of RhNAC31 transgenic plants to abscisic acid (ABA) both during and post-germination, causing lower germination and root inhibition rates under ABA treatment. Quantitative PCR experiments showed that numerous abiotic stress-related genes were activated by RhNAC31 overexpression. Our results highlight RhNAC31 as a positive transcriptional regulator of tolerance to multiple abiotic pressures, and we conclude that RhNAC31 has potential for use in the molecular breeding of stress-tolerant crops.
Severe eutrophication and harmful cyanobacterial blooms of freshwater ecosystems has been a persistent environmental topic in recent decades. Allelochemical inhibition has received great attention in aquatic ecology and quality management. This study investigates the growth and full photosynthesis performance of pyrogallol on Microcystis aeruginosa TY001. The growth and pigment contents of M. aeruginosa were seriously inhibited by pyrogallol. The relative expression levels of the nblA gene were up-regulated under pyrogallol treatments. Unexpectedly, the relative transcript abundance of the psaB and psbA genes significantly increased compared with the control, but the chlorophyll fluorescence parameters of M. aeruginosa TY001 decreased significantly, except at 1 mg L-1 pyrogallol. In conclusion, the target sites of pyrogallol’s toxic effect on the PSII of M. aeruginosa TY001 were mainly on the active reaction centers and the electron transport at the acceptor side.
 A novel antibacterial protein with a molecular mass of 44 kDa has been isolated from dried fruiting bodies of the wild mushroom Clitocybe sinopica. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis showed that the protein was composed of two subunits each with a molecular mass of 22 kDa. Its N-terminal amino-acid sequence, SVQATVNGDKML, has not been reported for other antimicrobial proteins. The purification protocol included ion exchange chromatography on DEAE-cellulose, CM-cellulose and Q-Sepharose, and gel filtration by fast protein liquid chromatography on Superdex 75. The antibacterial protein was adsorbed on all three ion exchangers. The antimicrobial activity profile of the protein against tested bacterial and fungal strains disclosed that it possessed potent antibacterial activity against Agrobacterium rhizogenes, A. tumefaciens, A. vitis, Xanthomonas oryzae and X. malvacearum with a minimum inhibitory concentration mostly below 0.6 μM. However, it had no antibacterial activity against Pseudomonas batatae, Erwinia herbicola, Escherichia coli, and Staphylococcus aureus, and no antifungal activity against Setosphaeria turcica, Fusarium oxysporum, Verticillium dahliae, Bipolaris maydis, and B. sativum. The antibacterial antivity against A. tumefaciens was stable after exposure to 20-60°C for 30 min and to pH 4-9 for 1 h.
The combined effects of drought and low light on biomass partition, foliar nitrogen concentration, membrane stability and active oxygen species (AOS) and antioxidant system were investigated in dragon spruce (Picea asperata Mast.) seedlings grown at two watering regimes (well-watered, 100% of field capacity and drought, 30% of field capacity) and light availabilities (HL, 100% of full sunlight and low light, 15% of full sunlight). Under high light condition drought not only reduced foliar nitrogen concentration (Nmass) and membrane stability index (MSI) but also significantly increased biomass partitioning to roots, AOS, ascorbic acid (AsA) content and antioxidant enzyme activities including superoxide dismutase (SOD, EC 1.15.1.1), peroxidase (POD, EC 1.11.1.7), catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11) and glutathione reductase(GR, EC 1.6.4.2). However, no prominently drought-induced differences in biomass partitioning to root, SOD, GR activities, hydrogen peroxide (H2O2) and MSI were observed in low light seedlings. On the other hand, significant interaction of drought and low light was found on MSI, the antioxidant enzymes activities (SOD, POD, CAT, APX, GR), H2O2 and superoxide radical (O2-). These results suggested that seedlings grown at the understory were more sensitive to drought than low light.
So far, azide has been consistently reported to act as an inhibitor of metal enzymes, especially copper proteins. The present work shows that azide can also act as an acti­vator of polyphenol oxidase II (PPO II) from tobacco leaves. From the square-wave voltammetry of native PPO II, peroxide-PPO II complex and azide-PPO II complex, the reduction of nitro blue tetrazolium by the enzymes and activation of PPO II by peroxide it follows that the binding of azide to PPO II induces the formation of CuO2 2-Cu in the active site of PPO II from CuO2 -Cu in native PPO II. The reason for azide acting as an activator can be attributed to azide complexing with PPO II, thus inducing the formation of CuO2 2-Cu, which is the active site of the peroxide-PPO II complex in which peroxide plays the role of activator.
Selenium deficiency in crops has become a subject of growing concern where soil Se concentration is low. The mechanisms of Se translocation in the soil-rice system is very complex and the influence of heavy metal elements and nutrient concentrations on Se translocation in the soil-rice system is unknown. Our study investigated concentrations of Se, heavy metals like Hg, Cd, and Pb, and nutrient elements like Ca, K, P, and S in soils and rice tissues (roots, stems, and grains) in different industrial regions in Jiangsu Province, China. The transfer of Se in the soil-rice system was calculated by transfer coefficients (TC Se) in this study. The results showed that Se transfer from soil to roots and from stems to grain were key steps for controlled Se concentration in rice grains. The multiple linear regression analysis makes an implication that some elements influence the Se transfer significantly: soil K and Hg may suppress Se entering rice roots; B, Cu, and Mo in rice root may restrain Se transfer from root to stem; and S, Cr, P, and Mg in rice stem had negative effects on Se accumulation in rice grain. Therefore, reducing heavy metal pollution and managing fertilizer amounts may elevate Se concentration in rice grain, especially when Se concentration in soils is low.
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