Exogenous calcium can enhance the resistance of certain plants to abiotic stress. Research have demonstrated that exogenous calcium could enhances the resistance of honeysuckle under salt stress by promoting the transmission of photosynthetic electrons.The aim of this study was to investigate the effects of exogenous calcium on the contents of Na~+,K~+,Ca~(2+),Mg~(2+)and the expression of photosynthetic related genes Cab and rbc L. In this study,we used ICP-OES to analysis ion contents and used qRT-PCR to analysis the expression patterns of Cab and rbc L. The results showed that CaCl_2 significantly enhanced the K~+-Na~+,Ca~(2+)-Na~+,Mg~(2+)-Na+ratio of honeysuckle treated with 50 and 100 mmol·L~(-1) NaCl. Meanwhile,Cab and rbc L were significantly up-regulated under short-term salt stress,and CaCl_2 promoted this trend. From the two gene expression patterns,rbc L rapidly up-regulated on the first day of stress and then decreased,and was more sensitive to environmental changes. In summary,exogenous calcium could alleviate salt stress and increase plant development by increasing intracellular K~+-Na~+,Ca~(2+)-Na~+,Mg~(2+)-Na+ratio,and the transient overexpression of Cab and rbc L.
Calcium ; physiology ; Cations ; analysis ; Lonicera ; physiology ; Photosynthesis ; Salt Stress

In this paper, a pot experiment using quartz sands was conducted to study the effects of different concentrations of NaCl (0, 25, 50, 75, 100 mmol·L⁻¹) on the ion absorption, distribution and essential oil components of flowering Schizonepeta tenuifolia. The results showed that as NaCl concentration increased, Na⁺ content of root, stem, leaf and flower increased significantly, and that of the aerial parts was in a higher level than in the root. Regarding the K⁺ content, it decreased in the root but increased in stem, leaf and flower. Some changes were detected in the Ca²⁺ content, but not significant on the whole. The value of K⁺/Na⁺ and Ca²⁺/Na⁺ reduced as a result of increasing NaCl concentrations. The content of essential oil increased under medium salt treatment (50 mmol·L⁻¹ NaCl). However, the synthesis and accumulation of essential oil was inhibited by the serious salt treatment (100 mmol·L⁻¹ NaCl). Over 98% of the essential oil components were terpenes, in which pulegone and menthone were the most two abundant compounds. Varieties of essential oil components did not change significantly under salt stress but their relative proportions did. The transformation of pulegone to menthone was enhanced and the value of pulegone/menthone based on their relative contents decreased with NaCl concentration increasing. Consequently, menthone ranked the most abundant compound by replacing pulegone. Relative content of D-limonene increased under medium and serious salt stress, and that of β-caryophyllene only increased under mild treatments. So our research could provide references for the standard cultivation on saline soil of S. tenuifolia.
Lamiaceae ; Oils, Volatile ; Plant Leaves ; Salt Stress ; Sodium ; Sodium Chloride

Salt stress may cause primary osmotic stress and ion toxicity, as well as secondary oxidative stress and nutritional stress in plants, which hampers the agricultural production. Salt stress-responsive transcription factors can mitigate the damage of salt stress to plants through regulating the expression of downstream target genes. Based on the soil salinization and its damage to plants, and the central regulatory role of transcription factors in the plant salt stress-responsive signal transduction network, this review summarized the salt stress-responsive signal transduction pathways that the transcription factors are involved, and the application of salt stress-responsive transcription factors to enhance the salt tolerance of plants. We also reviewed the transcription factors-regulated complex downstream gene network which is formed by forming homo- or heterodimers between transcription factors and by forming complexes with regulatory proteins. This paper provides a theoretical basis for understanding the role of salt stress-responsive transcription factors in the salt stress regulatory network, which may facilitate the molecular breeding for improved stress resistance.
Gene Expression Regulation, Plant ; Osmotic Pressure ; Plant Proteins/metabolism* ; Plants, Genetically Modified ; Salt Stress ; Salt Tolerance ; Stress, Physiological ; Transcription Factors/metabolism*

We studied the seed germination of Astragalus membranaceus under PEG and Na Cl osmotic stress gradients( 0,-0. 1,-0. 3,-0. 5,-0. 7 MPa) respectively applied with light( continuous light,light 12 h/dark 12 h circulation and continuous dark) and temperature( constant 15 ℃,15 ℃ 12 h/30 ℃ 12 h circulation and constant 30 ℃) treatments. The results showed as following: ① Under the light and temperature interactive treatments,total germination percentage( TGP) was restrained by high temperature and continuous light also decreased TGP under high temperature. Mean germination time( MGT) was not changed by light mode. Root development was enhanced by dark and low temperature. Shoot development was enhanced by light and high temperature. Hypocotyl length was enhanced by dark and high temperature. ② Under the light and temperature interactive treatments combined respectively with PEG and NaCl stress conditions,although the inhibitions of seed germination and growth were gradually strengthened with the increases of osmotic stresses,slight osmotic stress can promote seed germination. Under the same osmotic potential,the effects of PEG on TGPs and MGTs were stronger than that of NaCl. As the temperature increase,the seeds may change from photo-neutrality to photo-phobia. Decreased TGP under drought and continuous light interactive treatment is an adaptation strategy to avoiding drought. Hypocotyl growth accelerated under continuous dark treatment is an ecological trait which could increase dry matter input in stem and height for more light. Seed development under high concentration of NaCl treatment is better than that of PEG treatment due to low water potential caused by Na~+,which can enter into seed coat and promote water absorption.
Astragalus propinquus ; physiology ; radiation effects ; Droughts ; Germination ; Light ; Salt Stress ; Seeds ; physiology ; radiation effects ; Temperature

Exogenous calcium can enhance the resistance of certain plants to abiotic stress. However,the role of calcium insaltstressed honeysuckle is unclear. The study is aimed to investigate the effects of exogenous calcium on the biomass,chlorophyll content,gas exchange parameters and chlorophyll fluorescence of honeysuckle under salt stress. The results showed that the calcium-treated honeysuckle had better photochemical properties than the salt-stressed honeysuckle,such as PIABS,PItotal,which represents the overall activity of photosystemⅡ(PSⅡ),and related parameters for characterizing electron transport efficiency φP0,ψE0,φE0,σR,and φR are significantly improved. At the same time,the gas exchange parameters Gs,Ci,Trare also maintained at a high level. In summary,exogenous calcium protects the activity of PSⅡ,promotes the transmission of photosynthetic electrons,and maintains a high Ci,therefore enhances the resistance of honeysuckle under salt stress.
Calcium ; pharmacology ; Chlorophyll ; analysis ; Lonicera ; drug effects ; physiology ; Photosynthesis ; Plant Leaves ; Salt Stress

Heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria are aerobic microorganisms that can remove nitrogen under high-salt conditions, but their performance in practical applications are not satisfactory. As a compatible solute, trehalose helps microorganisms to cope with high salt stress by participating in the regulation of cellular osmotic pressure, and plays an important role in promoting the nitrogen removal efficiency of microbial populations in the high-salt environment. We investigated the mechanism of exogenous-trehalose-enhanced metabolism of HN-AD community under high-salt stress by starting up a membrane aerobic biofilm reactor (MABR) to enrich HN-AD bacteria, and designed a C₁₅₀ experimental group with 150 μmol/L trehalose addition and a C₀ control group without trehalose. The reactor performance and the community structure showed that NH₄⁺-N, total nitrogen (TN) and chemical oxygen demand (COD) removal efficiency were increased by 29.7%, 28.0% and 29.1%, respectively. The total relative abundance of salt-tolerant HN-AD bacteria (with Acinetobacter and Pseudofulvimonas as the dominant genus) in the C₁₅₀ group reached 66.8%, an 18.2% increase compared with that of the C₀ group. This demonstrated that trehalose addition promoted the enrichment of salt-tolerant HN-AD bacteria in the high-salt environment to enhance the nitrogen removal performance of the system. In-depth metabolomics analysis showed that the exogenous trehalose was utilized by microorganisms to improve proline synthesis to increase resistance to high-salt stress. By regulating the activity of cell proliferation signaling pathways (cGMP-PKG, PI3K-Akt), phospholipid metabolism pathway and aminoacyl-tRNA synthesis pathway, the abundances of phosphoethanolamine, which was one of the glycerophospholipid metabolites, and purine and pyrimidine were up-regulated to stimulate bacterial aggregation and cell proliferation to promote the growth of HN-AD bacteria in the high-salt environment. Meanwhile, the addition of trehalose accelerated the tricarboxylic acid (TCA) cycle, which might provide more electron donors and energy to the carbon and nitrogen metabolisms of HN-AD bacteria and promote the nitrogen removal performance of the system. These results may facilitate using HN-AD bacteria in the treatment of high-salt and high-nitrogen wastewater.
Nitrification ; Denitrification ; Trehalose ; Phosphatidylinositol 3-Kinases/metabolism* ; Heterotrophic Processes ; Salt Stress ; Nitrogen/metabolism* ; Aerobiosis ; Bioreactors/microbiology*

High salt content in soils severely hampers plant growth and crop yields. Many transcription factors in plants play important roles in responding to various stresses, but their molecular mechanisms remain unclear. WRKY transcription factors are one of the largest families of transcription factors in higher plants that are involved in and influence many aspects of plant growth and development. They play important roles in responding to salt stress. The regulation of gene expression by WRKY proteins is mainly achieved by binding to the DNA's specific cis-regulatory elements, the W-box elements (TTGACC). In recent years, there have been many studies revealing the roles and mechanisms of WRKY family members, from model plant Arabidopsis to agricultural crops. This paper reviews the latest research progress on WRKY transcription factors in response to salt stress and discusses the current challenges and future perspectives of WRKY transcription factor research.
Transcription Factors/metabolism* ; Plant Proteins/metabolism* ; Stress, Physiological/genetics* ; Salt Stress/genetics* ; Crops, Agricultural/genetics* ; Gene Expression Regulation, Plant ; Phylogeny ; Plants, Genetically Modified/genetics*

To study the molecular mechanism of salt stress response of peanut small GTP binding protein gene AhRabG3f, a 1 914 bp promoter fragment upstream of the start codon of AhRabG3f gene (3f-P) from peanut was cloned. Subsequently, five truncated fragments (3f-P1-3f-P5) with lengths of 1 729, 1 379, 666, 510 and 179 bp were obtained through deletion at the 5' end, respectively. Plant expression vectors where these six promoter fragments were fused with the gus gene were constructed and transformed into tobacco by Agrobacterium-mediated method, respectively. GUS expression in transgenic tobacco and activity analysis were conducted. The gus gene expression can be detected in the transgenic tobacco harboring each promoter segment, among which the driving activity of the full-length promoter 3f-P was the weakest, while the driving activity of the promoter segment 3f-P3 was the strongest. Upon exposure of the transgenic tobacco to salt stress, the GUS activity driven by 3f-P, 3f-P1, 3f-P2 and 3f-P3 was 3.3, 1.2, 1.9 and 1.2 times compared to that of the transgenic plants without salt treatment. This suggests that the AhRabG3f promoter was salt-inducible and there might be positive regulatory elements between 3f-P and 3f-P3 in response to salt stress. The results of GUS activity driven by promoter fragments after salt treatment showed that elements included MYB and GT1 between 1 930 bp and 1 745 bp. Moreover, a TC-rich repeat between 682 bp and 526 bp might be positive cis-elements responsible for salt stress, and an MYC element between 1 395 bp and 682 bp might be a negative cis-element responsible for salt stress. This study may facilitate using the induced promoter to regulate the salt resistance of peanut.
Arachis/genetics* ; Fabaceae/genetics* ; GTP-Binding Proteins/metabolism* ; Gene Expression Regulation, Plant ; Glucuronidase/metabolism* ; Plant Proteins/metabolism* ; Plants, Genetically Modified/genetics* ; Salt Stress ; Stress, Physiological/genetics* ; Tobacco/genetics*

In order to obtain salt-tolerant calli of Dandelion (Taraxacum officinale Weber), calli were induced from leaf explants of Dandelion on Murashige and Skoog's medium supplemented with 2.0 mg/L 6-benzyladenine and 0.5 mg/L 2,4-dichlorophen oxyacetic acid With 1.5% NaCl as selection pressure, most calli became brown and dead, whereas some new cell clusters appeared at the edge of the brown calli after 2 to 3 weeks. The survived cells were picked out and sub-cultured every 3 weeks onto the fresh selection medium and salt-tolerant calli were finally obtained through 4 continuous selections on the selection medium supplemented with 1.5% NaCl. Salt-tolerant calli increased steadily under a fixed NaCl stress though their relative growth rate decreased with increased NaCl concentration whereas the control calli which were sub-cultured by 4 continus selections on salt free medium ceased to grow under the same condition. This result indicated that the salt-tolerance of the selected calli is improved and this character is stable. Compared with the control, the SDS-PAGE pattern of the salt-tolerant calli had a unique 34 kD protein band. Its 30 kD and 18 kD protein bands were up-regulated. Further more, within the NaCl stress range up to 1.5%, the activities of antioxidant enzymes such as super oxidase dimutase, peroxidase and catalase, and the proline contents of the salt-tolerant calli were higher than those of the control. The results indicated that the selected calli with improved and stable salt tolerance were cell variants. The accumulation of the organic compatible solutes including proteins and the enhanced antioxidant capabilities in the salt tolerant calli are the two ways for them to regulate their osmotic homeostasis and alleviate the secondary reactive oxygen spexies damage respectively.
Adaptation, Physiological ; Cell Culture Techniques ; methods ; Drug Tolerance ; physiology ; Salt-Tolerant Plants ; genetics ; growth & development ; physiology ; Sodium Chloride ; pharmacology ; Stress, Physiological ; Taraxacum ; genetics ; growth & development ; physiology

The preliminary role of calcineurin B-like protein-interacting protein kinases (CIPKs) in stress response is defined but the exact function of OsCIPK10 gene in rice stress response and its expression pattern yet unclear. In this study we explored the possible functions of OsCIPK10 gene by reverse genetics approaches and also revealed its expression pattern by GUS staining. From the preliminary study of this gene we presumed its function to assist plant to resist stress but over-expressed OsCIPK10 rice transgenic lines showed no significant phenotypic differences from the wild type either under high salt or low potassium conditions, however the gene knockdown plants using inverted repeat strategy presented meaningful healthy plants compared to wild type under the stress of salt. Further we checked the expression profile under high salt and low potassium conditions in wild type and found that OsCIPK10 decreases under high salt and increases on low potassium conditions. So we speculate that OsCIPK10 is actually going to function in response to high salt and low potassium stress. We also explored the expression pattern of this gene using Gus staining and found that gene expresses in all plant tissues, the only exception observed was its higher expression in the vascular tissues.
Cloning, Molecular ; Genes, Plant ; Oryza ; enzymology ; genetics ; Plant Proteins ; genetics ; metabolism ; Plants, Genetically Modified ; genetics ; metabolism ; Potassium ; pharmacology ; Protein-Serine-Threonine Kinases ; genetics ; metabolism ; RNA Interference ; RNA, Small Interfering ; genetics ; Salt-Tolerant Plants ; genetics ; Sodium Chloride ; pharmacology ; Stress, Physiological