ACC oxidase (ACO) is one of the key enzymes that catalyze the synthesis of ethylene. Ethylene is involved in salt stress response in plants, and salt stress seriously affects the yield of peanut. In this study, AhACO genes were cloned and their functions were investigated with the aim to explore the biological function of AhACOs in salt stress response, and to provide genetic resources for the breeding of salt-tolerant varieties of peanut. AhACO1 and AhACO2 were amplified from the cDNA of salt-tolerant peanut mutant M29, respectively, and cloned into the plant expression vector pCAMBIA super1300. The recombinant plasmid was transformed into Huayu22 by pollen tube injection mediated by Agrobacterium tumefaciens. After harvest, the small slice cotyledon was separated from the kernel, and the positive seeds were screened by PCR. The expression of AhACO genes was analyzed by qRT-PCR, and the ethylene release was detected by capillary column gas chromatography. Transgenic seeds were sowed and then irrigated with NaCl solution, and the phenotypic changes of 21-day-seedings were recorded. The results showed that the growth of transgenic plants were better than that of the control group Huayu 22 upon salt stress, and the relative content of chlorophyll SPAD value and net photosynthetic rate (Pn) of transgenic peanuts were higher than those of the control group. In addition, the ethylene production of AhACO1 and AhACO2 transgenic plants were 2.79 and 1.87 times higher than that of control peanut, respectively. These results showed that AhACO1 and AhACO2 could significantly improve the salt stress tolerance of transgenic peanut.
Salt Tolerance/genetics* ; Arachis/genetics* ; Plant Breeding ; Ethylenes/metabolism* ; Plants, Genetically Modified/genetics* ; Gene Expression Regulation, Plant ; Plant Proteins/genetics*

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*

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*

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*

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*

Salinity is the most important factor for the growth of crops. It is an effective method to alleviate the toxic effect caused by salt stress using saline-alkali-tolerant and growth-promoting bacteria in agriculture. Seven salt-tolerant bacteria were screened from saline-alkali soil, and the abilities of EPS production, alkalinity reduction and IAA production of the selected strains were investigated. A dominant strain DB01 was evaluated. The abilities of EPS production, alkalinity reduction and IAA production of strain DB01 were 0.21 g/g, 8.7% and 8.97 mg/L, respectively. The isolate was identified as Halomonas aquamarina by partial sequencing analysis of its 16S rRNA genes, and had the ability to inhibit the growth of Fusarium oxysporum f. sp., Alternaria solani, Phytophthora sojae and Rhizoctonia cerealis. It also could promote root length and germination rate of wheat seedlings under salt stress. Halomonas aquamarina can provide theoretical basis for the development of soil microbial resources and the application in saline-alkali soil improvement.
Alkalies ; metabolism ; Bacteria ; drug effects ; genetics ; Halomonas ; genetics ; Plant Roots ; microbiology ; RNA, Ribosomal, 16S ; genetics ; Salt Tolerance ; genetics ; Seedlings ; growth & development ; microbiology ; Soil ; chemistry ; Soil Microbiology ; Triticum ; microbiology

In this study, Andrographis paniculata seedlings were used as experimental materials to study the effects of salicylic acid(SA) on the growth and effective component accumulation of A. paniculata under NaCl stress. The results showed that with the increase of NaCl concentration, the growth of A. paniculata seedlings was significantly inhibited, and the content of carotene and carotenoid decreased. The activity of antioxidant enzyme was enhanced. At the same time, the contents of proline, proline and soluble protein were on the rise. The contents of andrographolide, new andrographolide and deoxyandrographolide showed an upward trend, while deoxyandrographolide showed a downward trend. Treatment with 100 mmol·L~(-1) NaCl+5 mg·L~(-1) SA showed a significant increase in antioxidant enzyme activity in A. paniculata leaves. Treatment with 100 mmol·L~(-1) NaCl+10 mg·L~(-1) SA showed significant changes in soluble protein and proline content in A. paniculata leaves, while MDA content in A. paniculata leaves significantly decreased. 10 mg·L~(-1) SA had the best effect on the growth of A. paniculata seedlings under salt stress. Under the treatment of 50 mmol·L~(-1) NaCl+10 mg·L~(-1) SA, fresh weight, dry weight and leaf dry weight of A. paniculata seedlings reached the highest level, which were 1.02, 1.09 and 1.11 times of those in the control group, respectively. The concentrations of NaCl and 10 mg·L~(-1) SA were significantly higher than those of the control group. Four key enzyme genes of A. paniculata diterpene lactone synthesis pathway were selected to explore the molecular mechanism of salicylic acid to alleviate salt stress. With the increase of salt stress, the relative expressions of HMGR, GGPS and ApCPS were up-regulated, indicating that salt stress may enhance the synthesis of A. paniculata diterpene lactone through MVA pathway. SA can effectively promote the growth and development of A. paniculata under salt stress, improve its osmotic regulation and antioxidant capacity, improve its salt tolerance, and alleviate the effects of salt stress on A. paniculata.
Andrographis ; Plant Leaves ; Salicylic Acid ; Salt Tolerance ; Seedlings/genetics*

Salinity affects more than 6% of the world's total land area, causing massive losses in crop yield. Salinity inhibits plant growth and development through osmotic and ionic stresses; however, some plants exhibit adaptations through osmotic regulation, exclusion, and translocation of accumulated Na+ or Cl-. Currently, there are no practical, economically viable methods for managing salinity, so the best practice is to grow crops with improved tolerance. Germination is the stage in a plant's life cycle most adversely affected by salinity. Barley, the fourth most important cereal crop in the world, has outstanding salinity tolerance, relative to other cereal crops. Here, we review the genetics of salinity tolerance in barley during germination by summarizing reported quantitative trait loci (QTLs) and functional genes. The homologs of candidate genes for salinity tolerance in Arabidopsis, soybean, maize, wheat, and rice have been blasted and mapped on the barley reference genome. The genetic diversity of three reported functional gene families for salt tolerance during barley germination, namely dehydration-responsive element-binding (DREB) protein, somatic embryogenesis receptor-like kinase and aquaporin genes, is discussed. While all three gene families show great diversity in most plant species, the DREB gene family is more diverse in barley than in wheat and rice. Further to this review, a convenient method for screening for salinity tolerance at germination is needed, and the mechanisms of action of the genes involved in salt tolerance need to be identified, validated, and transferred to commercial cultivars for field production in saline soil.
Gene Expression Regulation, Plant ; Genetic Variation ; Germination/physiology* ; Hordeum/physiology* ; Salt Tolerance/genetics*

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

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