High Salinity Treatments Research Articles

The wheat salinity-induced R2R3-MYB transcription factor TaSIM confers salt stress tolerance in Arabidopsis thaliana

MYB transcription factors are a large family of proteins involved in plant development and responses to stress. In this study, the wheat salinity-induced R2R3-MYB transcription factor TaSIM was functionally characterized, with a focus on its role in salt stress tolerance. TaSIM protein enters the nucleus and binds to the MYB-binding site II motif. Expression analysis revealed that TaSIM was induced by drought, high salinity, low temperature, and abscisic acid treatment. Overexpression of TaSIM improved salt stress tolerance in transgenic plants. Furthermore, the transcript levels of genes involved in abscisic acid (ABA)-dependent (RD22) and ABA-independent (RD29A) signaling were higher in TaSIM-overexpressing plants than in the wild type. These results suggest that TaSIM positively modulates salt stress tolerance and has potential applications in molecular breeding to enhance salt tolerance in crops.

Genome-wide identification, functional prediction, and evolutionary analysis of the R2R3-MYB superfamily in Brassica napus.

R2R3-MYB transcription factors (TFs) have been shown to play important roles in plants, including in development and in various stress conditions. Phylogenetic analysis showed the presence of 249 R2R3-MYB TFs in Brassica napus, called BnaR2R3-MYB TFs, clustered into 38 clades. BnaR2R3-MYB TFs were distributed on 19 chromosomes of B. napus. Sixteen gene clusters were identified. BnaR2R3-MYB TFs were characterized by motif prediction, gene structure analysis, and gene ontology. Evolutionary analysis revealed that BnaR2R3-MYB TFs are mainly formed as a result of whole-genome duplication. Orthologs and paralogs of BnaR2R3-MYB TFs were identified in B. napus, B. rapa, B. oleracea, and Arabidopsis thaliana using synteny-based methods. Purifying selection was pervasive within R2R3-MYB TFs. Kn/Ks values lower than 0.3 indicated that BnaR2R3-MYB TFs are being functionally converged. The role of gene conversion in the formation of BnaR2R3-MYB TFs was significant. Cis-regulatory elements in the upstream regions of BnaR2R3-MYB genes, miRNA targeting BnaR2R3MYB TFs, and post translational modifications were identified. Digital expression data revealed that BnaR2R3-MYB genes were highly expressed in the roots and under high salinity treatment after 24 h. BnaMYB21, BnaMYB141, and BnaMYB148 have been suggested for improving salt-tolerant B. napus. BnaR2R3-MYB genes were mostly up regulated on the 14th day post inoculation with Leptosphaeria biglobosa and L. maculan. BnaMYB150 is a candidate for increased tolerance to Leptospheria in B. napus.

Abscisic acid: A key regulator of abiotic stress tolerance in plants

Phytohormones are key-regulators mediating environmental stress-responses and are the potential candidates for genetic manipulation to obtain abiotic stress tolerant crops. Plant stress responses occur through various signal transduction networks involving transcription factors regulating abscisic acid (ABA) signaling. The transcriptional regulation can occur in both ABA dependent manner via ABA-responsive element binding factors (ABF), MYC and MYB transcription factors and in an ABA-independent manner via drought-responsive element-binding factors (DREB). The transcript accumulation of RD29A gene is reported to be regulated in both ABA-dependent and ABA-independent manner and plays a vital role is stress tolerance. ABA is a quintessential messenger implicated in abiotic stress response in plants and synchronizes the expression of stress responsive proteins that play a major role in accumulation of compatible osmolytes, synthesis of Late Embryogenesis Abundant (LEA) proteins, dehydrins and other protective proteins. The foremost function of ABA is in the regulation of plant water balance and osmotic stress tolerance. In response to stress conditions, ABA is synthesized in different organs and initiates a cascade of signal transduction pathways that regulate an array of defense mechanisms against stress including regulation of stomatal aperture and expression of genes imparting resistance to environmental stresses. Among various transcription factors DREB2A/2B, AREB1, RD22BP1 and MYC/MYB regulate the ABA-responsive gene expression by interacting with their corresponding cis-acting elements viz. DRE/CRT(A/GCCGAC), ABRE (PyACGTGGC) and MYCRS(CANNTG)/MYBRS (C/TAACNA/G), respectively. These cis-acting elements have a role in inducing ABA dependent expression in plants under stress. cis-Elements such as ABA-responsive element (ABRE) are present upstream of the ABA-dependent stress responsive genes, that have a core sequence (PYACGTGGC) along with one or two coupling elements (CE) also found upstream of stress-responsive genes. ABA-regulated (ABR), ABA-dependent (ABD), VP1-dependent (VPD), VP1 and ABA-dependent (VAA), VP1 or ABA-dependent (VOA) are the five classes of ABA dependent gene promoters having ACTG flanking motifs and are known to be activated in response to plant stress. The ABRE-binding (AREB) proteins or ABRE-binding factors (ABFs) encode bZIP transcription factors among which AREB1/ABF2, AREB2/ABF4 and ABF3 are induced by dehydration, high salinity or ABA treatment in vegetative tissues, and are involved in enhanced drought stress tolerance. Present review is an attempt to discuss the role of transcription factors that regulate ABA signal transduction in response to abiotic stress.

Cloning, expression pattern, and potential role of apoptosis inhibitor 5 in the termination of embryonic diapause and early embryo development of Artemia sinica

During the embryonic development of Artemia sinica, the diapause phenomenon can be induced by high salinity or low temperature conditions. The diapause embryo at the gastrula stage is maintained under the threat of apoptosis to guarantee the embryo's normal development. In this process, apoptosis inhibitor proteins play vital roles in protecting embryos against apoptosis. Apoptosis inhibitor5 (API5) plays a pivotal role in regulating the cell cycle and preventing programmed cell death after growth factor starvation. In the present study, we cloned the full-length cDNA representing the api5 gene from A. sinica (As-api5), which encodes a 372-amino acid protein. In situ hybridization experiments revealed that As-api5 expression is not tissue or organ specific. Quantitative real-time PCR analyses of the developmental expression of As-api5 showed that it reached its highest level at 10h, after which its expression decreased. High salinity and low temperature treatments increased the expression of As-api5. Western blotting was used to assess the abundance of As-API5 and related proteins (As-CyclinA, As-CyclinE, As-E2F1, As-CDK2, As-APAF1, and As-Caspase9). Downregulation of As-api5 expression using a short interfering RNA resulted in increased mortality and embryo malformation of A. sinica. Taken together, the results indicated that API5 plays a crucial role in embryonic diapause termination and early embryo development of A. sinica.

Influence of temperature and salinity on tomato quality of a high value commercial cultivar

The combination of mild climate and soil salinity are the main causes of the exceptional fruit quality of some “flavour varieties” such as the hybrids of the Raf tomato. If conditions during fruit growth, mainly thermal and osmotic, are not adequate, the consumer does not always gets an acceptable fruit quality. The present work was conducted to study the effect of pre-harvest factors such as temperature and salinity on the quality of a high commercial value tomato cultivar. The experiment was conducted in a 12 m2 growth chamber, equipped with a control system for temperature, humidity and pure CO2 injection. Hybrid Raf tomato 'Dumas' grafted on Lycopersicon esculentum Mill. 'Arbiore' and grown in perlite substrate were exposed to four water salinity levels (2.5, 5.5, 8.0 and 12.0 dS m-1) and four day/night temperature regimes (20/14°C; 24/14°C; 28/14°C; 30/14°C). Salinity significantly increased soluble solid content (SSC) and titratable acidity (TA), but in contrast, the effect on pH was less responsive. Fruit firmness was strongly affected by salinity and adopted an inverse relationship from 24°C. Temperature affected significantly fruit quality at 28°C, quality parameters were reduced, except TA, which showed the highest values. Statistical analysis indicates an interaction between salinity and temperature, so that the reduction of quality parameters ​​caused by the temperature was less sensitive in the higher salinity treatments. The period of fruit development (PFD) was not affected by salinity in contrast, high temperature significantly reduced it. A strong direct relationship between PFD and the firmness was also observed. No differences in fruit quality parameters as affected by the different position of the trusses were observed. This study provides useful information to adjust climate control and fertigation set-points values in the cultivation of high value commercial tomato production.

Salinity tolerance of three Salix species: Survival, biomass yield and allocation, and biochemical efficiencies

Salinity tolerance is an important adaptive trait for land reclamation, particularly after petroleum extraction from the Athabasca oil sands “gigaproject” in western Canada. We compared survival, biomass yield and allocation, and biochemical efficiency for three willow species: Salix discolor (DIS), S. eriocephala (ERI), and S. interior (INT) grown under control (CTL) and medium and high salinity treatments (MST and HST, target EC = 1.5 and 3.0 mS cm−1, respectively). In HST, all DIS and ERI plants died, but 33% of INT plants survived. For DIS and ERI, total aboveground (AG) dry mass decreased from CTL to MST, whereas for INT, AG dry mass increased slightly in MST and also increased further in HST. Stem length was not influenced by salinity treatment; however, there was a significant treatment x species interaction for basal diameter resulting from a basal diameter decrease in DIS and ERI and increase in INT with increasing salinity. Maximum rate of carboxylation and electron transport showed equal or greater values for DIS and ERI in MST compared with CTL, but INT displayed a greater stimulation (1.3x) in the MST and HST. Across species and salinity treatments, corresponding biochemical efficiency traits showed a significant positive relationship to total AG dry mass, strongly supporting the theory of sink regulation of photosynthetic capacity. All final biomass and survival traits had significant genotype or genotype x salinity treatment interactions, but only one such effect was found for biochemical efficiency traits. The saline tolerance of INT may be due to natural selection in the arid regions of the southwest USA, where it is thought to have its evolutionary origins.

Effects of salinity and short-term elevated atmospheric CO2 on the chemical equilibrium between CO2 fixation and photosynthetic electron transport of Stevia rebaudiana Bertoni

The effect of water salinity on plant growth and photosynthetic traits of Stevia rebaudiana was investigated to determine its level and mechanisms of salinity tolerance. It was also attempted to assess how short-term elevated CO2 concentration would influence the boundaries and mechanisms of its photosynthetic capacity. The plants were grown in gravel/hydroponic system under controlled greenhouse conditions and irrigated with four different salinity levels (0, 25, 50 and 100 mol m−3NaCl). Low salinity did not significantly alter the plant fresh weight, which was substantially decreased by 67% at high salinity treatment. Salinity tolerance threshold was reached at 50 mol m−3 NaCl while C50 was between 50 and 100 mol m−3 NaCl, indicating that S. rebaudiana is a moderate salt tolerant species. Salt-induced growth reduction was apparently linked to a significant decline of about 47% in the photosynthetic rates (Anet) at high salinity treatment, leading consequently to a disequilibrium between CO2-assimilation and electron transport rates (indicated by enhanced ETRmax/Agross ratio). Elevated atmospheric CO2 enhanced CO2 assimilation rates by 65% and 80% for control and high-salt-stressed plants respectively, likely due to significant increases in intercellular CO2 concentration (indicated by enhanced Ci/Ca). The priority for Stevia under elevated atmospheric CO2 was not to save water but to maximize photosynthesis so that the PWUE was progressively improved and the threat of oxidative stress was diminished (decline in ETRmax/Agross). The results imply that elevated CO2 level could ameliorate some of the detrimental effects of salinity, conferring higher tolerance and survival of S. rebaudiana, a highlydesired feature with the forthcoming era of global changes.

Ethylenediamine‐N,N′‐disuccinic acid mitigates salt‐stress damages in strawberry by interfering with effects on the plant ionome

AbstractThis study evaluated the hypothesis that the organic chelant ethylenediamine‐N,N′‐disuccinic acid (EDDS) mitigates plant damage under salinity, and that this is accomplished by EDDS‐induced effects on cation uptake. Damaging effects of salinity on plants often involve inhibited uptake of nutritional cations, such as K and Ca, and excessive accumulation of Na. Therefore, mechanisms that improve uptake of K and Ca, or reduce Na uptake, have a potential for ameliorating salinity damages. Organic chelants increase heavy‐metal cation availability at the site of uptake and increase their uptake by the roots or in planta transport. Although organic chelants are routinely used in agriculture to enhance uptake of heavy‐metal cations into plants, and for soil bioremediation, their effect on uptake of cation‐macronutrients is not known, and neither is their impact on plant function under salinity. In this study, we evaluated the response of strawberry plants to EDDS application (0, 1, 3 and 5 mmol kg soil−1), under six levels of NaCl (0, 3, 6, 9, 12 and 15 mmol L−1). EDDS application under salinity improved vegetative development, as well as reproductive growth and chlorophyll content, with statistically significant interaction between chelant dosage and level of salinity. The mitigation of salinity damage by EDDS occurred at high salinity treatments (from 9 mM NaCl). Application rates of 1–3 mmol EDDS kg−1 were optimal for mitigating salinity effects on reproductive development, but in accordance with the extent of chelant‐induced accumulation of the macronutrients K, Ca and P in the leaves, higher application rates (3–5 mmol EDDS kg−1) were required for optimal improvement of vegetative development. These results suggest that EDDS improves plant function under mild salinities by interfering with salinity effects on the plant ionome.

Cotton GhERF38 gene is involved in plant response to salt/drought and ABA.

ERF (ethylene-responsive factor) transcription factors play important roles in plant stress signaling transduction pathways. However, their specific roles during diverse abiotic stresses tolerance in Gossypium hirsutum are largely unknown. Here, a novel ERF transcription factor, designated GhERF38, homologous to AtERF38 in Arabidopsis, was isolated from cotton (Gossypium hirsutum L). GhERF38 expression was up-regulated by salt, drought and ABA treatments. Subcellular localization results indicated that GhERF38 was localized in the cell nucleus. Over-expression of GhERF38 in Arabidopsis reduced plant tolerance to salt and drought stress as indicated by a decline of seed germination, plant greenness frequency, primary roots length and the survival rate in transgenic plants compared to those of wild type plants under salt or drought treatment. Besides, stress tolerance related physiological parameters such as proline content, relative water content, soluble sugar and chlorophyll content were all significantly lower in transgenic plants than those of wild type plants under salt or drought treatment. Furthermore, over-expression of GhERF38 in Arabidopsis resulted in ABA sensitivity in transgenic plants during both seed germination and seedling growth. Interestingly, the stomatal aperture of guard cells in the transgenic plants was larger than that in transgenic plant after ABA treatment, suggesting that GhERF38-overexpressing plants were insensitive to ABA in terms of stomatal closure. Furthermore, expressions of the stress-related genes were altered in the GhERF38 transgenic plants under high salinity, drought or ABA treatment. Together, our results revealed that GhERF38 functions as a novel regulator that is involved in response to salt/drought stress and ABA signaling during plant development.

Biofilm formation and granule properties in anaerobic digestion at high salinity

For the anaerobic biological treatment of saline wastewater, Anaerobic Digestion (AD) is currently a possibility, even though elevated salt concentrations can be a major obstacle. Anaerobic consortia and especially methanogenic archaea are very sensitive to fluctuations in salinity. When working with Upflow Sludge Blanket Reactor (UASB) technology, in which the microorganisms are aggregated and retained in the system as a granular biofilm, high sodium concentration negatively affects aggregation and consequently process performances. In this research, we analysed the structure of the biofilm and granules formed during the anaerobic treatment of high salinity (at 10 and 20 g/L of sodium) synthetic wastewater at lab scale. The acclimated inoculum was able to accomplish high rates of organics removal at all the salinity levels tested. 16S rRNA gene clonal analysis and Fluorescence In Situ Hybridization (FISH) analyses identified the acetoclastic Methanosaeta harundinacea as the key player involved acetate degradation and microbial attachment/granulation. When additional calcium (1 g/L) was added to overcome the negative effect of sodium on microbial aggregation, during the biofilm formation process microbial attachment and acetate degradation decreased. The same result was observed on granules formation: while calcium had a positive effect on granules strength when added to UASB reactors, Methanosaeta filaments were not present and the degradation of the partially acidified substrate was negatively influenced. This research demonstrated the possibility to get granulation at high salinity, bringing to the forefront the importance of a selection towards Methanosaeta cells growing in filamentous form to obtain strong and healthy granules.

Effects of increased seawater salinity irrigation on growth and quality of the edible halophyte Mesembryanthemum crystallinum L. under field conditions

Saline agriculture may answer to the declining availability of fresh water and to the worldwide expanding area of salinized soils by exploiting seawater and salt-affected soils for sustainable food production. Potential salt tolerant crops can be found among edible halophytes. Moreover, plants growing in saline environments are often associated with an enhanced endogenous concentrations of high-nutrient compounds. Mesembryanthemum crystallinum L. provides an interesting perspective in becoming a salt-tolerant and high-value crop at saline conditions, but has never been tested at representative agricultural conditions. This study aimed at assessing the effects of increasing levels of seawater salinity irrigation (electrical conductivity: 2, 4, 8, 12, 16, 20, and 35dSm−1) on growth and productive performance in a field experiment. Also, impacts of salinity on the functional value of edible leaves were evaluated by investigating the mineral elements, carotenoids, soluble sugars, and phenolic concentrations, along with antioxidant activity. Our results demonstrate that none of the salinity treatments negatively affected M. crystallinum biomass production. Furthermore, increased salinity extended the vegetative stage, leading to one extra month of harvest compared to non-saline conditions. Juvenile edible leaves' biomass, succulence and calcium concentrations even increased with increasing salinity. No differences were assessed in the phenolics concentration and antioxidant activity of high salinity treatments plants compared to the control. This paper demonstrates the perspective to cultivate M. crystallinum in saline agriculture, up to EC of 20–35dSm−1, or perhaps even higher, since we did not identify a threshold of biomass reduction. Only the Na+ concentration in the edible leaves could constitute a health concern or allow it acting as a natural salt substitute. This excellent performance in combination with the appreciated taste and its glistening appearance, may pave the way for use of the ice plant as high-value saline crop.

Transcriptome analysis reveals sunflower cytochrome P450 CYP93A1 responses to high salinity treatment at the seedling stage

Sunflower (Helianthus annuus) is an important global source of plant lipids and protein for food and other industries. Salinity is an abiotic stress that affects sunflower yield. Although recent studies have revealed that the cytochrome P450 (CYP) 93 family is involved in biotic and abiotic stresses, the relationship between the CYP93A gene and salt stress is not well understood in sunflower. In the present study, we performed transcriptome analysis of a relatively salt-tolerant sunflower variety ‘Xinkui 10’ at the seedling stage under high salinity treatment. Following de novo assembly, 66,426 unigenes were obtained, 45,724 (68.83%) of which were annotated. 5,852 differentially expressed genes (DEGs) were identified 11 distinct clusters in which three main clusters (K1–K3) accounted for 94.39% of DEGs. Mapman analysis showed that CYP450 genes were greatly enriched in cluster K3 and one continuously up-regulated gene, HaCYP93A1, was identified among 248 common DEGs in the transcriptome of ‘Xinkui 10’. Real-time quantitative RT-PCR (qRT-PCR) analysis indicated that transcript levels of HaCYP93A1 were induced by high salinity and jasmonic acid (JA) in roots. Meanwhile, three JA-biosynthesis genes (allene oxide cyclase 3 [AOC3], lipoxygenase 3 [LOX3], and allene oxide synthase [AOS]) in roots were up-regulated under salinity treatment. Moreover, correlation analysis indicated that the expression of HaCYP93A1 was markedly related with the JA-biosynthesis genes. Our results suggested that HaCYP93A1 might be involved in the salt tolerance pathway by regulating JA signaling in sunflower.

The Histone Deacetylase Inhibitor Suberoylanilide Hydroxamic Acid Alleviates Salinity Stress in Cassava.

Cassava (Manihot esculenta Crantz) demand has been rising because of its various applications. High salinity stress is a major environmental factor that interferes with normal plant growth and limits crop productivity. As well as genetic engineering to enhance stress tolerance, the use of small molecules is considered as an alternative methodology to modify plants with desired traits. The effectiveness of histone deacetylase (HDAC) inhibitors for increasing tolerance to salinity stress has recently been reported. Here we use the HDAC inhibitor, suberoylanilide hydroxamic acid (SAHA), to enhance tolerance to high salinity in cassava. Immunoblotting analysis reveals that SAHA treatment induces strong hyper-acetylation of histones H3 and H4 in roots, suggesting that SAHA functions as the HDAC inhibitor in cassava. Consistent with increased tolerance to salt stress under SAHA treatment, reduced Na+ content and increased K+/Na+ ratio were detected in SAHA-treated plants. Transcriptome analysis to discover mechanisms underlying salinity stress tolerance mediated through SAHA treatment reveals that SAHA enhances the expression of 421 genes in roots under normal condition, and 745 genes at 2 h and 268 genes at 24 h under both SAHA and NaCl treatment. The mRNA expression of genes, involved in phytohormone [abscisic acid (ABA), jasmonic acid (JA), ethylene, and gibberellin] biosynthesis pathways, is up-regulated after high salinity treatment in SAHA-pretreated roots. Among them, an allene oxide cyclase (MeAOC4) involved in a crucial step of JA biosynthesis is strongly up-regulated by SAHA treatment under salinity stress conditions, implying that JA pathway might contribute to increasing salinity tolerance by SAHA treatment. Our results suggest that epigenetic manipulation might enhance tolerance to high salinity stress in cassava.

Effects of drought and salt stresses on growth characteristics of euhalophyte Suaeda salsa in coastal wetlands

The pot experiment was carried out in the Yellow River Delta to investigate the effects of drought and salt stresses on growth characteristics of Suaeda salsa, and to reveal the role of nitrogen (N) application in alleviation effects of drought and salt stresses on Suaeda salsa in coastal wetlands. In this study, plants were exposed to two water contents treatments (i.e., 14% and 26% water content), four salinity treatments (i.e., 2 g/kg, 4 g/kg, 6 g/kg, and 8 g/kg NaCl) and two N application treatments (i.e., 0 and 200 N mg/kg) in field conditions. Growth characteristics of Suaeda salsa were assessed as fresh weight, dry weight, height, total nitrogen (TN) and total carbon (TC). Our results showed that fresh weight, dry weight and height of Suaeda salsa promoted at lower salinity treatments but reduced at higher salinity treatments, while TN and TC contents kept stable with increasing salinity levels. Drought stress diminished the fresh weight, dry weight and height of Suaeda salsa, whereas enhanced TN contents. Under the interactive stresses of drought and salt, fresh weight and dry weight showed slight increases at lower salinity treatments, whereas decreases at higher salinity treatments. N application promoted the fresh weight, dry weight and TN contents other than the height and TC contents of Suaeda salsa. The interaction between N application and salt stress exhibited a significant influence on the fresh weight and dry weight of Suaeda salsa, whereas no significant interaction between N application and drought stress was observed. These findings of this study suggested that higher salinity, drought and the interaction of drought and higher salinity would retard the growth of Suaeda salsa, whereas N application could only mitigate the deleterious effects of salt stress on Suaeda salsa.

盐度对互花米草枯落物分解释放硅、碳、氮元素的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 盐度对互花米草枯落物分解释放硅、碳、氮元素的影响 DOI: 10.5846/stxb201607261527 作者: 作者单位: 福建师范大学 地理研究所,福建师范大学 地理研究所,福建师范大学 地理研究所,福建师范大学 地理科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目（41401114）；福建省基金面上资助项目（2016J01184）；福建省教育厅资助项目（JA14082） Effect of salinity on silicon, carbon, and nitrogen during decomposition of Spartina alterniflora litter Author: Affiliation: Institute of Geography, Fujian Normal University,Institute of Geography, Fujian Normal University,Institute of Geography, Fujian Normal University, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为了研究潮汐湿地盐度对枯落物分解过程中硅、碳、氮元素释放的影响，通过室内模拟不同盐度（0、5、15和30）对互花米草枯落物茎和叶分解释放过程中硅、碳、氮元素的动态变化进行测定。结果表明：（1）互花米草茎和叶枯落物失重率和分解速率均随盐度增加而降低。（2）互花米草茎和叶枯落物分解水体中硅含量均随着盐度升高而增加，并且盐度30处理下，枯落物分解硅释放量显著高于盐度0和5（P < 0.05）。而分解末期生物硅残留量则随盐度升高而降低。（3）不同盐度处理茎枯落物分解碳释放量无显著差异，但叶枯落物分解碳释放量在盐度5、15和30处理中显著高于淡水（P < 0.05）。（4）互花米草茎枯落物分解释放到水中的NH4+-N含量随着盐度的升高而减少，NO3--N含量与之相反。研究单因素盐度对枯落物分解及元素释放的影响，可以为预测潮汐湿地枯落物分解对盐水入侵的响应机制提供参考，为湿地生源要素生物地球化学循环过程研究提供基础依据。 Abstract:To investigate the effect of salinity on silicon, carbon, and nitrogen values during decomposition of wetland litter, the changing dynamics of silicon, carbon, and nitrogen in Spartina alterniflora stems and leaves under different salinities (0, 5, 15, and 30) were analyzed in the laboratory. The results showed that the percentage weight loss and decomposition rate of litter decreased with increasing salinity. The silicon release concentrations of litter increased with higher salinity, and were significantly greater in the high salinity treatment (30) than in the freshwater(0) and low salinity(5) treatments (P < 0.05). In contrast, the biogenic silica (BSi) residual contents demonstrated an opposite trend during the terminal decomposition. The carbon contents released from the stem were not significantly different between the different salinity treatments, but the leaf were lower in the freshwater treatment than in the other treatments (P < 0.05). In the higher salinity treatments, the stem litter had higher NH4+-N release, with NO3--N contents shown to be the opposite. Salinity impact studies on litter decomposition and element release provides reference information for decomposition responses of tidal wetland litter to saltwater intrusion and is the basis for further research on biogeochemical cycles of biogenic elements in wetlands. 参考文献 相似文献 引证文献

Application of stable isotopes to examine N proportions within a simulated Aegiceras corniculatum wetland

Salinity levels and drought status of coastal wetlands may be strongly affected by climate change, and changes in the nitrogen cycle of mangrove wetlands may also be affected. We established combinations of three salinity and water levels with applied stable isotope 15N to study the δ15N distributions in the sediment and plants of a greenhouse-based simulated mangrove Aegiceras corniculatum wetland system. The stable isotope 13C and 15N, C and N contents and the C:N ratio were determined. Results showed that increasing in salinity significantly increased the δ13C value in plant organs. The δ15N value of plant organs increased with increasing water level in low salinity (10‰) and medium salinity (20‰) treatment groups but not in the high salinity (30‰) treatment group. This may attributed to A. corniculatum adjusting the δ15N distribution in different organs in response to high salinity stress. Compared to the δ13C, the δ15N values of plant were strongly affected by salinity and water level treatments, indicating that the behavior of N cycle was somewhat different than the C cycle, and affected by the combined effects of both salinity and water level. Most of 15N absorbed by plant tissues were in leaves except for the highest salinity and high water level treatment, showing at increasing water level, the proportion of 15N increased in root. Overall, the measured indicators exhibited different responses to salinity level and water level, suggesting that the changes in salinity and water levels have an impact on N cycling processes of wetland systems.

A Ramie bZIP Transcription Factor BnbZIP2 Is Involved in Drought, Salt, and Heavy Metal Stress Response.

bZIP transcription factors play key roles in plant growth, development, and stress signaling. A bZIP gene BnbZIP2 (GenBank accession number: KP642148) was cloned from ramie. BnbZIP2 has a 1416 base pair open reading frame, encoding a 471 amino acid protein containing a characteristic bZIP domain and a leucine zipper. BnbZIP2 shares high sequence similarity with bZIP factors from other plants. The BnbZIP2 protein is localized to both nuclei and cytoplasm. Transcripts of BnbZIP2 were found in various tissues in ramie, with significantly higher levels in female and male flowers. Its expression was induced by drought, high salinity, and abscisic acid treatments. Analysis of the cis-elements in promoters of BnbZIP2 identified cis-acting elements involved in growth, developmental processes, and a variety of stress responses. Transgenic Arabidopsis plants' overexpression of BnbZIP2 exhibited more sensitivity to drought and heavy metal Cd stress during seed germination, whereas more tolerance to high-salinity stress than the wild type during both seed germination and plant development. Thus, BnbZIP2 may act as a positive regulator in plants' response to high-salinity stress and be an important candidate gene for molecular breeding of salt-tolerant plants.

Sodium Chloride Effects on Water and Nutrient Uptake Efficiency in Sarcocornia fruticosa Containerized Production

ABSTRACTThe ability to produce native plants well adapted to the saline conditions without the production of nutrient-rich runoff will be a boon to nurseries hoping to reduce their environmental contamination impact and water use while at the same time producing quality plants to be used in the restoration of saline lands. Sarcocornia fruticosa plants were grown for 8 weeks in plastic containers with a source of sphagnum peat moss and perlite (80:20 v/v) to evaluate the effect of two salinity levels (2.0 (low-salinity treatment) and 7.5 dS m−1 (high-salinity treatment)) on plant growth, nutrient concentration in leachate and water and nutrient uptake efficiency and their losses. Leachate was collected to determine the runoff volume and composition, which included nitrate-nitrogen (NO3–N), phosphate-phosphorus (PO43–P) and potassium (K+) concentrations. Plant dry weight (DW) and nutrient content were determined in plants at the beginning and at the end of the experiment to establish the nutrient balance. Increasing salinity levels of irrigation water did not reduce either the plant DW or the water-use efficiency (WUE), but increased the volume of leachate per plant. The nutrient concentrations in leachates without significant differences between salt treatments exceeded the thresholds established by environmental guidelines, leading to a great risk of pollution. Based on nutrient balance, the irrigation with a higher salinity level reduced the plant nutrient uptake efficiency (10%, 18% and 12% for nitrogen (N), phosphorus (P) and potassium (K), respectively) and increased the nutrient losses (6% N, 7% P and 8% K), resulting in the recommendation to grow this species with the low salinity level based on the highest nutrient-use efficiency and the lowest levels of nutrient losses.

Vermicompost improves the physiological and biochemical responses of blessed thistle (Silybum marianum Gaertn.) and peppermint (Mentha haplocalyx Briq) to salinity stress

In this study, we examined whether vermicompost enhances a plant’s tolerance to salinity. We analyzed the physiological responses of the aerial parts and roots of the herbal stress-resistant plants blessed thistle and peppermint with NaCl and cow manure vermicompost and inorganic fertilizer. Salinity greatly enhanced the accumulation of malondialdehyde (MDA) and proline in the aerial parts and roots of the two species, but did not affect chlorophyll content. The K+/Na+ and Ca2+/Na+ ratios and the total soluble protein content were decreased in the aerial parts and roots under salinity conditions in both species. Under normal conditions, vermicompost enhanced plant growth and increased the K+/Na+ and Ca2+/Na+ ratios and total soluble protein content while inorganic fertilizer treatment increased the total soluble protein content and proline content in both species. Proline content in both species was greatly decreased under vermicompost treatment than inorganic treatment under normal conditions. Furthermore, under high salinity conditions, vermicompost treatment significantly reduced the MDA content and increased total soluble protein content and the K+/Na+ and Ca2+/Na+ ratios than stress-treated plants. Vermicompost had complex effects on the antioxidant enzyme activities of plants grown under high salinity treatment. Our results show vermicompost mitigates the effects of salinity stress.

Proteomic Response of Hordeum vulgare cv. Tadmor and Hordeum marinum to Salinity Stress: Similarities and Differences between a Glycophyte and a Halophyte.

Response to a high salinity treatment of 300 mM NaCl was studied in a cultivated barley Hordeum vulgare Syrian cultivar Tadmor and in a halophytic wild barley H. marinum. Differential salinity tolerance of H. marinum and H. vulgare is underlied by qualitative and quantitative differences in proteins involved in a variety of biological processes. The major aim was to identify proteins underlying differential salinity tolerance between the two barley species. Analyses of plant water content, osmotic potential and accumulation of proline and dehydrin proteins under high salinity revealed a relatively higher water saturation deficit in H. marinum than in H. vulgare while H. vulgare had lower osmotic potential corresponding with high levels of proline and dehydrins. Analysis of proteins soluble upon boiling isolated from control and salt-treated crown tissues revealed similarities as well as differences between H. marinum and H. vulgare. The similar salinity responses of both barley species lie in enhanced levels of stress-protective proteins such as defense-related proteins from late-embryogenesis abundant family, several chaperones from heat shock protein family, and others such as GrpE. However, there have also been found significant differences between H. marinum and H. vulgare salinity response indicating an active stress acclimation in H. marinum while stress damage in H. vulgare. An active acclimation to high salinity in H. marinum is underlined by enhanced levels of several stress-responsive transcription factors from basic leucine zipper and nascent polypeptide-associated complex families. In salt-treated H. marinum, enhanced levels of proteins involved in energy metabolism such as glycolysis, ATP metabolism, and photosynthesis-related proteins indicate an active acclimation to enhanced energy requirements during an establishment of novel plant homeostasis. In contrast, changes at proteome level in salt-treated H. vulgare indicate plant tissue damage as revealed by enhanced levels of proteins involved in proteasome-dependent protein degradation and proteins related to apoptosis. The results of proteomic analysis clearly indicate differential responses to high salinity and provide more profound insight into biological mechanisms underlying salinity response between two barley species with contrasting salinity tolerance.