Effects of Salinity on Metabolic Profiles, Gene Expressions, and Antioxidant Enzymes in Halophyte Suaeda salsa

Halophyte Suaeda salsa is native to the saline soil in the Yellow River Delta. Soil salinity can reduce plant productivity and therefore is the most important factor for the degradation of wetlands in the Yellow River Delta. In this work we characterized the salinity-induced effects in S. salsa in terms of metabolic profiling, antioxidant enzyme activities, and gene expression quantification. Our results showed that salinity inhibited plant growth of S. salsa and upregulated gene expression levels of myo-inositol-1-phosphate synthase (INPS), choline monooxygenase (CMO), betaine aldehyde dehydrogenase (BADH), and catalase (CAT), and elevated the activities of superoxide dismutase (SOD), peroxidase (POD), CAT, and glutathione peroxidase (GPx). The significant metabolic responses included the depleted amino acids malate, fumarate, choline, phosphocholine, and elevated betaine and allantoin in the aboveground part of S. salsa seedlings as well as depleted glucose and fructose and elevated proline, citrate, and sucrose in root tissues. Based on these significant biological markers, salinity treatments induced clear osmotic stress (for example, INPS, CMO, BADH, betaine, proline) and oxidative stress (for example, SOD, POD, CAT, GPx activities), disturbed protein biosynthesis/degradation (amino acids and total protein) and energy metabolism (for example, glucose, sucrose, citrate) in S. salsa.     

Root morphology is related to the phenotypic variation in waterlogging tolerance of two populations of Suaeda salsa under salinity

The effects of waterlogging and salinity on seedling emergence, seedling growth and ion accumulation in a euhalophyte Suaeda salsa in an intertidal zone and on saline inland soil were investigated. Seedlings of S. salsa from the intertidal zone emerged more rapidly than those of the inland population under both waterlogged and drained conditions. Waterlogging and salinity had no adverse effects on seedling emergence of S. salsa from the intertidal zone, but markedly inhibited this parameter in the inland population. Waterlogging did not affect the seedling survival, shoot dry mass, and shoot height in high salinity in S. salsa from the intertidal zone, while the opposite trend was shown in the inland population. The root dry mass was higher in S. salsa from the intertidal zone as compared to the inland population, in waterlogged treatments by 1.9, 1.3, and 1.5 times in 1, 200, and 600 mM NaCl, respectively, and in drained treatments by 1.8, 2.3, and 3.0 times in 1, 200, and 600 mM NaCl, respectively. Waterlogging increased Na⁺ and K⁺ concentrations in high salinity, but waterlogging had no effect on Cl^- concentration in shoots of S. salsa from the intertidal zone. In all NaCl treatments, waterlogging had no effect on concentrations of these ions in shoots of S. salsa from the saline inland site. In a field investigation, the fresh mass of shoots and roots were lower, whereas the root/shoot ratio was 1.5 times higher in S. salsa from the intertidal zone, compared with the inland population. These findings indicate that S. salsa population from the intertidal zone is more waterlogging tolerant than the inland population. S. salsa from the intertidal zone produced relatively more root biomass and this might help anchor plants against tidal action in the intertidal zone. The physiological and morphological characteristics may determine the natural distributions of the two S. salsa populations in their different saline environments.     

Effect of salinity on growth, ion accumulation and the roles of ions in osmotic adjustment of two populations of Suaeda salsa

The effect of salinity on growth, ion accumulation and the roles of ions in osmotic adjustment of two populations of Suaeda salsa were investigated. Seeds were collected from an intertidal zone or a saline inland zone in the Yellow River Delta in Shandong province, China. Seedlings were exposed to 10, 100, 200, 400 or 600 mM NaCl for 18 days in a greenhouse. NO₃ ^? concentration in the soil where S. salsa grows in an intertidal zone was much lower than that for the second population, but leaf NO₃ ^? concentration was the same in the two populations under field conditions. When plants were cultured in a greenhouse under natural light conditions, S. salsa from the intertidal zone showed fewer main stem branches and lower relative shoot growth compared to S. salsa from saline inland. Leaf Cl^? concentration of saline inland S. salsa was significantly higher than that of S. salsa from the intertidal zone, while the opposite was true for the concentration of NO₃ ^? in leaves of plants. For S. salsa from the intertidal zone NO₃ ^? contributed more than Cl^? to the osmotic potential, whereas S. salsa from the saline inland exhibited a reverse relationship under saline conditions, indicating that NO₃ ^? plays an important osmotic role in S. salsa from the intertidal zone in high salinity. In conclusion, S. salsa from the intertidal zone may employ superior control of ion uptake and content than S. salsa from the saline inland zone. The two populations of Suaeda salsa presented different ability in chloride exclusion and nitrate accumulation. These characteristics may affect the distributions of S. salsa in natural highly saline environments.     

Effect of salinity on germination,seedling emergence,seedling growth and ion accumulation of a euhalophyte Suaeda salsa in an intertidal zone and on saline inland

The effect of salinity on germination, seedling emergence, seedling growth and ion accumulation of a euhalophyte Suaeda salsa L. in an intertidal zone and on saline inland were investigated. Brown seeds of S. salsa were heavier and better developed than black seeds in both the intertidal zone and on saline inland. The brown seeds/black seeds ratio for S. salsa in the intertidal zone was much higher than that for S. salsa on saline inland. More germinated seeds grew as seedlings under high salinity for S. salsa from the intertidal zone than S. salsa on saline inland; high salinity decreased the shoot length more severely for S. salsa from saline inland than for S. salsa from the intertidal zone; the seedling growth at a range of NaCl, measured either as shoot length or shoot dry weight, for S. salsa from the intertidal zone was lower than that of S. salsa from saline inland. In conclusion, for S. salsa from the intertidal zone there appears to be selection for slower growth and producing more brown seeds. The establishment of populations of S. salsa in different saline environments depends on the responses of seed germination, seedling emergence and seedling growth to salinity. These characteristics may determine the natural distributions of S. salsa populations in different saline environments.     

碱蓬浮床对海水养殖尾水中氮磷修复效果研究

海水养殖尾水中总氮、总磷超标是引起沿海水体富营养化的主要原因,为研究碱蓬浮床对海水养殖尾水中氮磷的去除效果,该研究设计加入碱蓬(Suaeda salsa)浮床和不加浮床的两组对比实验,通过比较修复前后碱蓬株高、生物量、含水率、根长以及各部位氮、磷的含量变化,以及水体中总氮(TN)和总磷(TP)的去除效果,探究浮床中碱蓬对总氮和总磷的吸收及其生长特性,验证碱蓬浮床对海水养殖废水中氮、磷等的去除能力。结果表明:浮床中碱蓬株高、鲜重、干重、含水率、根长较修复前均有显著增加,说明浮床中盐生植物碱蓬能够适应含海水养殖尾水水培环境;经碱蓬浮床修复,水体中总氮、总磷均明显下降,其中碱蓬对海水养殖尾水中的总氮总磷去除贡献率分别为16.10%和78.15%,浮床中碱蓬会在叶片和根系中积累氮磷。     

Using euhalophytes to understand salt tolerance and to develop saline agriculture: Suaeda salsa as a promising model

Background As important components in saline agriculture, halophytes can help to provide food for a growing world population. In addition to being potential crops in their own right, halophytes are also potential sources of salt-resistance genes that might help plant breeders and molecular biologists increase the salt tolerance of conventional crop plants. One especially promising halophyte is Suaeda salsa, a euhalophytic herb that occurs both on inland saline soils and in the intertidal zone. The species produces dimorphic seeds: black seeds are sensitive to salinity and remain dormant in light under high salt concentrations, while brown seeds can germinate under high salinity (e.g. 600 mm NaCl) regardless of light. Consequently, the species is useful for studying the mechanisms by which dimorphic seeds are adapted to saline environments. S. salsa has succulent leaves and is highly salt tolerant (e.g. its optimal NaCl concentration for growth is 200 mm). A series of S. salsa genes related to salt tolerance have been cloned and their functions tested: these include SsNHX1, SsHKT1, SsAPX, SsCAT1, SsP5CS and SsBADH. The species is economically important because its fresh branches have high value as a vegetable, and its seed oil is edible and rich in unsaturated fatty acids. Because it can remove salts and heavy metals from saline soils, S. salsa can also be used in the restoration of salinized or contaminated saline land.Scope Because of its economic and ecological value in saline agriculture, S. salsa is one of the most important halophytes in China. In this review, the value of S. salsa as a source of food, medicine and forage is discussed. Its uses in the restoration of salinized or contaminated land and as a source of salt-resistance genes are also considered.     

Exposure-dose-response of Tellina deltoidalis to metal-contaminated estuarine sediments: 1. Cadmium spiked sediments

Cadmium is a ubiquitous environmental metal contaminant with an affinity for biological membranes; it can enter cells by facilitated transport and it binds therein to various biomolecules and affects membrane system function. The relationship between cadmium exposure, dose and response was investigated in the benthic, deposit feeding, marine bivalve Tellina deltoidalis, using 28 day microcosm spiked cadmium exposures. Tissue cadmium reached steady state with the exposure concentration. Half the accumulated cadmium was detoxified and with increased exposure more was converted into metal rich granules. Most biologically active cadmium was in the mitochondrial fraction, with up to 7320-fold cadmium increases in exposed organisms. Cadmium exposed T. deltoidalis generally had reduced glutathione peroxidase enzyme activity. An increase in total glutathione concentrations, due to a build up of oxidised glutathione, was indicated by the reduced to oxidised glutathione ratio. All cadmium exposed T. deltoidalis had reduced total antioxidant capacity that corresponded with increased lipid peroxidation, lysosomal destabilisation and micronuclei frequency. Clear exposure-dose-response relationships have been demonstrated for T. deltoidalis exposed to cadmium-spiked sediments, supporting this organism's suitability for laboratory or in situ evaluation of sediment cadmium toxicity.     

Incorporating thresholds into understanding salinity tolerance: A study using salt‐tolerant plants in salt marshes

Although salinity in many ecosystems such as salt marshes can be extremely high, an asymmetry in salinity range between experimental studies (relatively narrow) and field conditions (potentially broad) has strongly affected current understanding of plant salinity tolerance. To improve understanding, it is thus important to examine plant tolerances over a broad range of salinities and identify potential tolerance thresholds. We examine tolerances of two widely distributed marsh plants, Suaeda salsa and Salicornia europaea, to salinities ranging from 0 to 100 g/kg, and determine survival, above‐ and belowground biomass after 8 weeks of salinity treatment. Both species, Sa. europaea in particular, have much broader salinity tolerances than other plants previously examined, (2) plant survival, above‐ and belowground biomass have remarkably different responses to salinity, and (3) there is a nonlinear, threshold response of S. salsa to salinity, above which S. salsa survivorship drastically decreases. These results provide multiple important insights. Our study suggests that the potential for using these halophytes to revegetate and restore salt‐affected land may be greater than previously thought, and highlights the importance of studying multiple plant responses. Importantly, our study calls for a better integration of thresholds into understanding plant salinity tolerances and their applications.     

Vitamins E and C ameliorate the oxidative stresses induced by zinc oxide nanoparticles on liver and gills of Oreochromis niloticus

The current study evaluated the hazards of Zinc oxide nanoparticles (ZnONPs) on Nile Tilapia liver and gill antioxidants enzymes activities and antioxidants genes expressions. The ameliorative action of vitamins E and C mixture was investigated. Two hundred males of Nile Tilapia were exposed to one and two mg?L^?1 of ZnONPs either with or without vitamin C and E mixture for 7 and 15?days. Glutathione reductase (GR), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities and gene expression as well glutathione (GSH) and lipid peroxide (LPO) levels were investigated. The results revealed that the exposure to ZnONPs could induce alterations in the liver and gills antioxidants and LPO of Nile Tilapia. Moreover, the mixture of vitamin E and C highly effective in alleviation the toxic effect of ZnONPs.     

盐胁迫下3种滨海盐生植物的根系生长和分布

我国广大滨海地区的盐土上发育着大量的盐生植物,这些植物的根系对维持土壤稳定性,减小风蚀和水蚀具有重要作用。在水培条件下,针对碱蓬、盐角草和盐地碱蓬3种滨海盐生植物,研究它们在不同盐浓度条件下根系分布的差异。结果表明:一定浓度的盐分可以促进3种盐生植物生长,但较高浓度的盐抑制其生长,特别是对根系生长的抑制作用更大。在同样盐浓度下,盐地碱蓬的生长最快,生物量也最大。在盐分浓度较低时,3种盐生植物的主根长和总根长都有所增加,与对照相比,盐角草增加的幅度较大,但高浓度的盐会抑制根系总长度的增加,其中盐角草较碱蓬和盐地碱蓬抑制的程度轻。盐分对3种植物的根系平均直径没有显著的影响,但有减小的趋势。在水培条件下,碱蓬和盐角草的根系上、中、下部分布的较均匀,而盐地碱蓬的根系中部比上部和下部有显著的增加,盐分对每种植物的根系的分布没有显著的影响。从根系的分布特征可以推断:盐角草比碱蓬和盐地碱蓬具有较强的抗盐性和耐瘠薄能力;碱蓬的耐盐能力较其它两种植物差,盐角草的耐盐性最强。根据3种滨海盐生植物的根系生长和分布特征,证明这3种植物的根系分属于2种功能型,碱蓬是浅根系功能型,盐角草和盐地碱蓬是深根系功能型。根系分布的参数表明3种滨海盐生植物中盐地碱蓬是用来加强土壤稳定性最好的植物。     

Canopy spectral characteristics of typical invasive and native plants in the coastal wetland of Yancheng City,China

Spartina alterniflora (S. alterniflora) is a dominant invasive alien species that occurs in Yancheng Wetland National Nature Reserve, the largest coastal wetland in China. It expands rapidly and exerts great threats to local ecosystem. The main native species there are Phragmites australis (P. australis) and Suaeda salsa (S. salsa), respectively. In order to monitor their dynamics, it is of great significance to analyze their spectral discrimination. Canopy spectra of these typical species were measured in July and October in order to compare species differences, as well as the seasonal variation. The Normalized Difference Vegetation Index (NDVI) was calculated based on canopy spectra. The significances of differences in spectral characteristic among species were tested using the one-way analysis of variance (ANOVA) (P < 0.05). The results showed that the visible (VI) bands were the optimum wavelengths for species discrimination in both seasons. S. alterniflora always had the greatest green peak height and red absorption depth. S. salsa had no obvious green peak, but an obvious red reflection peak. P. australis generally had intermediate values. Spectra in the near-infrared (NIR) bands were not appropriate for delineating S. alterniflora and P. australis in summer, as they showed similar values in these wavelengths. But NIR bands could be used to distinguish S. salsa in summer, as it had significantly lower reflectance in NIR bands than the others. Meanwhile, the reflectance in short-wavelength infrared (SWIR) bands became another suitable approach for distinguishing species in autumn. S. salsa had significantly higher values than the others in SWIR regions. Significant NDVI differences between different species proved that it could improve the species discrimination. S. alterniflora always had the highest NDVI values, while S. salsa had the lowest values. The seasonal trend of canopy spectra was also revealed. With plant maturity, the reflectance values in green bands and NIR bands decreased significantly, but increased significantly around the yellow-red wavelengths. The green peak heights, red absorption depths, and NDVI values of the species decreased remarkably. Furthermore, S. alterniflora and P. australis illustrated obvious ‘blue shift’ of the red edge with senescence. These results pointed out the the potential bands and appropriate spectral parameters appropriate for species discrimination, and highlighted the influence of seasonality on spectral information. They provided an important basis for salt marshes identification and dynamic monitoring on a large scale.     

The antioxidant system in Suaeda salsa under salt stress

ABSTRACTSuaeda salsaL. is a typical euhalophyte and is widely distributed throughout the world. Suaeda plants are important halophyte resources, and the physiological and biochemical characteristics of their various organsand their response to salt stress have been intensively studied. Leaf succulence, intracellular ion localization, increased osmotic regulation and enhanced antioxidant capacities are important responses for Suaeda plants to adapt to salt stress. Among these responses, scavenging of reactive oxygen species (ROS) is an important mechanism for plants to withstand oxidative stress and improve salt tolerance. The generation and scavenging pathways of ROS, as well as the expression of scavenging enzymes change under salt stress. This article reviews the antioxidant system constitute of S. salsa, and the mechanisms by which S. salsaantioxidant capacity is improved for salt tolerance. In addition, the differences between types of antioxidant mechanisms in S. salsaare reviewed, thereby revealing the adaptation mechanisms of Suaeda to different habitats. The review provides important clues for the comprehensive understanding of the salt tolerance mechanisms of halophytes.KEYWORDS: Suaeda salsa, halophyte, salt-tolerance mechanism, oxidative stress, antioxidant system     

Interactive effects of salinity and water depth on the growth of Melaleuca ericifolia Sm. (Swamp paperbark) seedlings

Melaleuca ericifolia Sm. (Swamp paperbark) is a common tree species in freshwater and brackish wetlands in southern and eastern Australia. The survival of this species in many wetlands is now threatened by increased salinity and inappropriate water regimes. We examined the response of 5-month-old M. ericifolia seedlings to three water depths (exposed, waterlogged and submerged) at three salinities (2, 49 and 60 dS m⁻¹). Increasing water depth at the lowest salinity did not affect survival, but strongly inhibited seedling growth. Total biomass, leaf area and maximum root length were highest in exposed plants, intermediate in waterlogged plants and lowest in submerged plants. Although completely submerged plants survived for 10 weeks at the lowest salinity, they demonstrated negative growth rates and were unable to extend their shoots above the water surface. At the higher salinities, M. ericifolia seedlings were intolerant of waterlogging and submergence: all plants died after 9 weeks at 60 dS m⁻¹. Soil salinities increased over time, and by Week 10, exceeded external water column salinities in both the exposed and waterlogged treatments. In exposed sediment, ∼90% of plants survived for 10 weeks at 60 dS m⁻¹ even though soil salinities reached ∼76 dS m⁻¹. No mortality occurred in the exposed plants at 49 dS m⁻¹, and small but positive relative growth rates were recorded at Week 10. We conclude that at low salinities M. ericifolia seedlings are highly tolerant of sediment waterlogging, but are unlikely to tolerate prolonged submergence. However, at the higher salinities, M. ericifolia seedlings are intolerant of waterlogging and submergence and died rapidly after 5 weeks exposure to this combination of environmental stressors. This research demonstrates that salinity may restrict the range of water regimes tolerated by aquatic plants.     

Antioxidative Defense Potential to Salinity in the Euhalophyte Salicornia brachiata

The antioxidative defense mechanism to salinity was assessed by monitoring the activities of some antioxidative enzymes and levels of antioxidants in an obligate halophyte, Salicornia brachiata, subjected to varying levels of NaCl (0, 200, 400, and 600 mM) under hydroponic culture. In the shoots of S. brachiata, salt treatment preferentially enhanced the activities of ascorbate peroxidase (APX), guaiacol peroxidase (POX), glutathione reductase (GR), and superoxide dismutase (SOD), whereas it induced the decrease of catalase (CAT) activity. Similarly, salinity caused an increase in total glutathione content (GSH + GSSG) and a decrease in total ascorbate content. Growth of S. brachiata was optimum at 200 mM NaCl and decreased with further increase in salinity. Salinity caused an increase in Na⁺ content and a decrease in K⁺ content of shoots. Proline levels did not change at low (0-200 mM NaCl) or moderate (400 mM NaCl) salinities, whereas a significant increase in proline level was observed at high salinity (600 mM NaCl). Accumulation of Na⁺ may have a certain role in osmotic homeostasis under low and moderate salinities in S. brachiata. Parameters of oxidative stress such as malondialdehyde (MDA), a product of lipid peroxidation, and H₂O₂ concentrations decreased at low salinity (200 mM NaCl) and increased at moderate (400 mM NaCl) and high salinities (600 mM NaCl). As a whole, our results suggest that the capacity to limit ionic and oxidative damage by the elevated levels of certain antioxidative enzymes and antioxidant molecules is important for salt tolerance of S. brachiata.     

Effects of Selenium and L-Carnitine on Oxidative Stress in Blood of Rat Induced by 2.45-GHz Radiation from Wireless Devices

The levels of blood lipid peroxidation, glutathione peroxidase, reduced glutathione, and vitamin C were used to follow the level of oxidative damage caused by 2.45 GHz electromagnetic radiation in rats. The possible protective effects of selenium and L-carnitine were also tested and compared to untreated controls. Thirty male Wistar Albino rats were equally divided into five groups, namely Groups A₁ and A₂: controls and sham controls, respectively; Group B: EMR; Group C: EMR + selenium, Group D: EMR + L-carnitine. Groups B–D were exposed to 2.45 GHz electromagnetic radiation during 60 min/day for 28 days. The lipid peroxidation levels in plasma and erythrocytes were significantly higher in group B than in groups A₁ and A₂ (p?<?0.05), although the reduced glutathione and glutathione peroxidase values were slightly lower in erythrocytes of group B compared to groups A₁ and A₂. The plasma lipid peroxidation level in group A₂ was significantly lower than in group B (p?<?0.05). Erythrocyte reduced glutathione levels (p?<?0.01) in group B; erythrocyte glutathione peroxidase activity in group A₂ (p?<?0.05), group B (p?<?0.001), and group C (p?<?0.05) were found to be lower than in group D. In conclusion, 2.45 GHz electromagnetic radiation caused oxidative stress in blood of rat. L-carnitine seems to have protective effects on the 2.45-GHz-induced blood toxicity by inhibiting free radical supporting antioxidant redox system although selenium has no effect on the investigated values.     

Salinity improves chilling resistance in Suaeda salsa

Suaeda salsa L., a C3 euhalophytic herb, is native to saline soils, demonstrates high resistance to salinity stress. The effect of chilling stress on S. salsa under high salinity, particularly the change in unsaturated fatty acid content within membrane lipids, has not been investigated. After a 12 h chilling treatment (4 °C) performed under low irradiance (100 μmol m^?2 s^?1), the chlorophyll contents, maximal photochemical efficiency of photosystem II (F _v/F _m) and actual PSII efficiency (ΦPSII) were determined. These measurements were significantly decreased in S. salsa leaves in the absence of salt treatment yet there were no significant changes with a 200 mM NaCl treatment. Chlorophyll contents, F _v/F _m and ΦPSII in S. salsa under 200 mM NaCl were higher than those without salt treatment. The unsaturated fatty acid content and the double bond index (DBI) of major membrane lipids of monogalactosyldiacylglycerols, digalactosyldiacylglycerols (DGDG), sulphoquinovosyldiacylglycerols and phosphatidylglycerols (PG) significantly increased following the chilling treatment (4 °C) (with 12 h of low irradiance and 200 mM of NaCl). The DBI of DGDG and PG was decreased in the absence of the salt treatment. These results suggest that in the euhalophyte S. salsa, a 200 mM NaCl treatment increases chilling tolerance under conditions of low irradiance (100 μmol m^?2 s^?1).     

Differential effects of H2S on cytoplasmic and nuclear thiol concentrations in different tissues of Brassica roots

H₂S-fumigation experiments with the sulphur-demanding plant Brassica oleracea L. (hybrid curly kale) were carried out to modulate glutathione levels in root tip cells. Plants were exposed in small fumigation cabinets to 0.4 μl l^–1 H₂S for 96 h. The data obtained by HPLC analysis of bimane-labeled thiols showed a slight increase of glutathione contents of about 20% in the roots of H₂S fumigated plants. The histochemical non-destructive assay for the determination of glutathione in single cells of whole plant organs was carried out for the first time by the use of monochlorobimane (BmCl) in situ to give a fluorescent GSH–bimane conjugate, followed by a fixation procedure. A significant increase of the fluorescence signal after the H₂S treatment was localized in the cytoplasm as well as in the nucleoplasm of root meristem cells.     

Contents of volume 137 1991

The halophyte, Suaeda salsa, was grown in saline soil in pots and watered with a NaCl solution containing 0.2 g L^-1 Na-ions. S. salsa accumulated Na during a 120-day growing period and caused a net reduction in the Na content of the soil. S. salsa also decreased the Na content of saline soil in a field experiment. The Na content of the soil at depth 20–30 cm was reduced by 4.5% with S. salsa at a density of 15 plants m^-2 and by 6.7% with a density of 30 plants m^-2. In contrast, the Na content was decreased by only 1% with Medicago sativa at 15 plant m^-2 and increased by 3.8% with bare soil. The results confirm that S. salsa is an effective salt absorber in saline soils.