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At least 145 records · Page 8Linked to original sources
PubMed2001

Improved salt tolerance of transgenic tobacco expressing apoplastic yeast-derived invertase.

We investigated the salt tolerance of transgenic tobacco, in which yeast invertase is expressed in the apoplastic (Apo-Inv) spaces. Whereas photosynthetic activities in wild-type tobacco in light were inhibited under salt stress, transgenic Apo-Inv tobacco maintained constant photosynthetic activities. The physical appearance of plants under salt stress also indicates that yeast invertase expression in the apoplastic space is beneficial for inducing salt tolerance. Apo-Inv tobacco had a much higher osmotic pressure increase in the cell sap than did wild-type tobacco under this type of stress. The physiological importance of sucrose metabolism under salt stress is discussed.

Chloroplasts↗
PubMed2003

Lipid composition of mangrove and its relevance to salt tolerance.

Lipid compositions of mangrove trees were studied in relation to the salt-tolerance mechanism. Leaves and roots were obtained from seven mature mangrove trees on Iriomote Island, Okinawa: Bruguiera gymnorrhiza, Rhizophora stylosa, Kandelia candel, Lumnitzera racemosa, Avicennia marina, Pemphis acidula and Sonneratia alba. Lipids of mangrove leaves mainly consisted of 11 lipid classes: polar lipids, unknown (UK) 1-6, sterols, triacyl glycerols, wax ester and sterol ester (UK 3 and 4 were found to be tri-terpenoid alcohol in this study). Of these lipid classes, sterol ester was the main lipid in all species comprising 17.6-33.7% of total lipids. Analysis of the chemical structure found that the sterol esters mainly consisted of fatty acid esters of tri-terpenoid alcohols. One major tri-terpenoid alcohol was identified to be lupeol by interpretation of infrared resonance, nuclear magnetic resonance and mass spectrometry. Because of the unique anatomy of the mangrove root, lipid analyses were made separately for epidermis, cortex and innermost stele, respectively. The concentration of free tri-terpenoid alcohols showed a higher tendency in the outside part than in the inside portion of the roots, suggesting their protective roles. Relevance of lipid composition to salt tolerance was studied with propagules of K. candel and B. gymnorrhiza planted with varied salt concentrations. The proportions of free tri-terpenoids increased with salinity in both leaves and roots of K. candel, and only in roots of B. gymnorrhiza. No salt-dependent changes were noted in the phospholipid and fatty acid compositions in both species. These findings suggested that salt stress specifically modulated the terpenoid concentrations in mangroves.

Adaptation, Physiological↗
PubMed2006

Increasing salt tolerance in the tomato.

In this paper, a number of strategies to overcome the deleterious effects of salinity on plants will be reviewed; these strategies include using molecular markers and genetic transformation as tools to develop salinity-tolerant genotypes, and some cultural techniques. For more than 12 years, QTL analysis has been attempted in order to understand the genetics of salt tolerance and to deal with component traits in breeding programmes. Despite innovations like better marker systems and improved genetic mapping strategies, the success of marker-assisted selection has been very limited because, in part, of inadequate experimental design. Since salinity is variable in time and space, experimental design must allow the study of genotype x environment interaction. Genetic transformation could become a powerful tool in plant breeding, but the growing knowledge from plant physiology must be integrated with molecular breeding techniques. It has been shown that the expression of several transgenes promotes a higher level of salt tolerance in some species. Despite this promising result, the development of a salt-tolerant cultivar by way of transgenesis has still not been achieved. Future directions in order to overcome the present limitations are proposed. Three cultural techniques have proved useful in tomato to overcome, in part, the effects of salinity: treatment of seedlings with drought or NaCl ameliorates the adaptation of adult plants to salinity; mist applied to tomato plants grown in Mediterranean conditions improves vegetative growth and yield in saline conditions; and grafting tomato cultivars onto appropriate rootstocks could reduce the effects of salinity.

Breeding↗
PubMed2006

A proteomic approach towards the analysis of salt tolerance in Rhizobium etli and Sinorhizobium meliloti strains.

Soluble proteins from the salt-tolerant Rhizobium etli strain EBRI 26 were separated by two-dimensional (2D) gel electrophoresis and visualised by Commassie staining. Six proteins are highly expressed after induction by 4% NaCl compared to the non-salt-stressed cells. These proteins have pI between 5 and 5.5 and masses of approximately 22, 25, 40, 65, 70, and 95 kDa. These proteins were analysed by Matrix-assisted laser adsorption ionization time of flight (MALDI-TOF) after digestion with trypsin. Despite having very good peptide mass fingerprint data, these proteins could not be identified, because the genome sequence of R. etli is not yet published. In a second approach, soluble proteins from salt-induced or non-salt-induced cultures from R. etli strain EBRI 26 were separately labelled with different fluorescent cyano-dyes prior to 2D difference in gel electrophoresis. Results revealed that 49 proteins are differentially expressed after the addition of sodium chloride. Fourteen proteins are overexpressed and 35 were downregulated. The genome of Sinorhizobium meliloti, a closely related species to R. etli, has been published. Similar experiments using Sinorhizobium meliloti strain 2011 identified four overexpressed and six downregulated proteins. Among the overexpressed protein is a carboxynospermidin decarboxylase, which plays an important role in the biosynthesis of spermidin (polyamine). The enzyme catalase is among the downregulated proteins. These proteins may play a role in salt tolerance.

Bacterial Proteins↗
PubMed2026

Desert-derived Ensifer sp. SA403 enhances potato salt tolerance by reshaping rhizosphere microbiome functions and host responses.

Soil salinization increasingly threatens global food security, and potato (Solanum tuberosum L.), a moderately salt-sensitive crop, is particularly vulnerable to saline soils. Plant growth-promoting rhizobacteria (PGPR) offer a promising strategy to improve crop performance, yet how PGPR interact with native microorganisms to enhance potato salt tolerance remains poorly understood. In this study, we identified a desert-derived PGPR strain, Ensifer sp. SA403, which substantially enhanced potato performance under high salinity across sterile, non-sterile and field conditions. Physiologically, inoculation with SA403 reduced shoot Na⁺ accumulation and increased the K⁺/Na⁺ ratio; notably, these effects were markedly stronger in non-sterile substrates than under sterile conditions, indicating that SA403-mediated ion homeostasis relies on cooperation with the resident microbiota rather than on the strain acting alone. Metagenomic profiling indicated that SA403 strain reshaped rhizosphere communities, significantly enriching beneficial taxa such as Priestia and Bradyrhizobium, and upregulated functional pathways involved in glutathione and sulfur metabolism. Furthermore, host transcriptomic analyses showed that SA403 modulated plant responses to salt stress, with differentially expressed genes enriched in jasmonic acid signaling, ethanolamine metabolism and amino-acid biosynthesis pathways. Field trials on saline soils confirmed that SA403 significantly increased seedling emergence and tuber weight. Together, our results demonstrate that SA403 functions as a biological mediator that optimizes rhizosphere microecology and coordinates ion balance and host signaling to enhance potato salt tolerance. These findings support the potential of SA403 as a robust PGPR-based tool for sustainable potato production on saline soils.

Rhizosphere↗
PubMed2002

Biochemical characterization of the Arabidopsis protein kinase SOS2 that functions in salt tolerance.

The Arabidopsis Salt Overly Sensitive 2 (SOS2) gene encodes a serine/threonine (Thr) protein kinase that has been shown to be a critical component of the salt stress signaling pathway. SOS2 contains a sucrose-non-fermenting protein kinase 1/AMP-activated protein kinase-like N-terminal catalytic domain with an activation loop and a unique C-terminal regulatory domain with an FISL motif that binds to the calcium sensor Salt Overly Sensitive 3. In this study, we examined some of the biochemical properties of the SOS2 in vitro. To determine its biochemical properties, we expressed and isolated a number of active and inactive SOS2 mutants as glutathione S-transferase fusion proteins in Escherichia coli. Three constitutively active mutants, SOS2T168D, SOS2T168D Delta F, and SOS2T168D Delta 308, were obtained previously, which contain either the Thr-168 to aspartic acid (Asp) mutation in the activation loop or combine the activation loop mutation with removal of the FISL motif or the entire regulatory domain. These active mutants exhibited a preference for Mn(2+) relative to Mg(2+) and could not use GTP as phosphate donor for either substrate phosphorylation or autophosphorylation. The three enzymes had similar peptide substrate specificity and catalytic efficiency. Salt overly sensitive 3 had little effect on the activity of the activation loop mutant SOS2T168D, either in the presence or absence of calcium. The active mutant SOS2T168D Delta 308 could not transphosphorylate an inactive protein (SOS2K40N), which indicates an intramolecular reaction mechanism of SOS2 autophosphorylation. Interestingly, SOS2 could be activated not only by the Thr-168 to Asp mutation but also by a serine-156 or tyrosine-175 to Asp mutation within the activation loop. Our results provide insights into the regulation and biochemical properties of SOS2 and the SOS2 subfamily of protein kinases.

Adaptation, Physiological↗
PubMed2002

Phenotype/genotype associations for yield and salt tolerance in a barley mapping population segregating for two dwarfing genes.

Barley traits related to salt tolerance are mapped in a population segregating for a dwarfing gene associated with salt tolerance. Twelve quantitative trait loci (QTLs) were detected for seven seedling traits in doubled haploids from the spring barley cross Derkado x B83-12/21/5 when given saline treatment in hydroponics. The location of QTLs for seedling growth stage (leaf appearance rate), stem weight prior to elongation, and tiller number are reported for the first time. In addition, four QTLs were found for the mature plant traits grain nitrogen and plot yield. In total, seven QTLs are co-located with the dwarfing genes sdw1, on chromosome 3H, and ari-e.GP, on chromosome 5H, including seedling leaf response (SGa) to gibberellic acid (GA(3)). QTLs controlling the growth of leaves (GS2) on chromosomes 2H and 3H and emergence of tillers (TN2) and grain yield were independent of the dwarfing genes. Field trials were grown in eastern Scotland and England to estimate yield and grain composition. A genetic map was used to compare the positions of QTLs for seedling traits with the location of QTLs for the mature plant traits. The results are discussed in relation to the study of barley physiology and the location of genes for dwarf habit and responses to GA.

Adaptation, Physiological↗
PubMed1998

Characterization of a second gene (ZSOD22) of Na+/H+ antiporter from salt-tolerant yeast Zygosaccharomyces rouxii and functional expression of ZSOD2 and ZSOD22 in Saccharomyces cerevisiae.

We reported in our previous paper on the characterization of the Na+/H(+)-antiporter gene (ZSOD2) closely related to the salt-tolerance of yeast Zygosaccharomyces rouxii. In the present paper, we have cloned a second gene (ZSOD22) of Na+/H+ antiporter from Z. rouxii. The deduced amino acid sequence of Zsod22p was highly homologous to that of Zsod2p, Sod2p from Schizosaccharomyces pombe, and Nhalp from Saccharomyces cerevisiae. The open reading frames (ORFs) from ZSOD2 or ZSOD22 were inserted into a yeast expression vector pYES2, and their constructs (pZSOD2 and pZSOD22) were used to transform the salt-sensitive S. cerevisiae. pZSOD2- or pZSOD22-harboring-recombinant S. cerevisiae cells showed increases in salt tolerance. However, the Z. rouxii disruptant of ZSOD22 did not show any phenotypes related to salt tolerance or osmotolerance, unlike that of ZSOD2. The transcriptional expression of ZSOD22 was not observed by Northern blot analysis even in Z. rouxii cells subjected to NaCl-shock. From these results we conclude that although Z. rouxii includes at least two copies of the Na+/H(+)-antiporter gene (ZSOD2 and ZSOD22), ZSOD2 encodes a functional product as an antiporter and ZSOD22 is poorly transcribed, if at all.

Amino Acid Sequence↗
PubMed1983

Mutagenicity of pyrolysates of salt-tolerant bacteria from food and cigarettes.

Smoke condensates obtained by pyrolysis of the cells of microorganisms isolated from food and cigarettes and of laboratory cultures were shown to be mutagenic to Salmonella typhimurium TA98 and TA100 in incorporation with liver microsomal fraction S-9 mix. The smoke condensates from salt-tolerant bacteria, which belonged to Micrococcus, Bacillus and Corynebacterium spp., showed higher mutagenic activity than those from other less salt-tolerant organisms, fish flesh or pork. Smoke deriving from microorganisms, especially salt-tolerant ones, in food or cigarettes as well as from food components might take part in human carcinogenesis because of the correlation between mutagenicity and carcinogenicity.

Bacteria↗
PubMed2001

[Subcloning and sequencing of DNA fragment related to salt tolerance in Sinorhizobium meliloti 042B].

A 4 kb ClaI DNA fragment related to salt tolerance from S. meliloti 042B was digested by HindIII down 2.4 kb fragment, and a 1.6 kb ClaII-HindIII fragment was retained on plasmid pML122. Then, the 2.4 kb DNA fragment was ligated with plasmid pBBR1-MCS2, and the recombinant plasmid was transformed to E. coli DH5 alpha, and transformant GS2 was obtained. Three-parental mating experiments were carried out with transformant GS2 as donor, salt sensitive strains GZ17 as recipient and pRK2013 as helper plasmid, then the transconjugant GG2 was selected on FY plates containing kanamycin and 0.4 mol/L NaCl. The remaining DNA fragment was self ligated with pML122 and then transformed into E. coli S17-1 and transformat GS0 was obtained. Two-parental mating experiment was carried out with transformant GS0 as donor and salt sensitive strain GZ17 as recipient, but no transconjugant was obtained on the FY plates. Then, the 2.4 kb HindIII DNA fragment was ligated into sequencing vector pGEM-7Zf(+) for sequencing. The result of sequencing and analysis showed that the 2.4 kb DNA fragment contained three ORFs. According to the result of sequencing, further subcloning was conducted and 1.9 kb HindIII-Sac II DNA fragment related to salt tolerance was obtained.

Amino Acid Sequence↗
PubMed2005

The use of cell membrane stability (CMS) technique to screen for salt tolerant wheat varieties.

Cell membrane stability (CMS) technique was used to screen salt tolerant (V1, V2), salt sensitive (V5) and two salt/water deficiency tolerant wheat genotypes (V3 and V4) using 100-250 mM NaCl salinity maintained in pots containing gravel and nutrient solution. The objectives were to study: (i) the reliability of CMS technique for screening wheat under high salinity, (ii) factors that impart stability and/or injury to the cell membrane, and (iii) the relationship of CMS with other physiological parameters affected by the salt stress. Generally, cellular injury increased with increasing salinity levels. In V5, it was the highest (74.2%) at 250 mM, probably due to combined effect of Na+ toxicity and low (54%) relative water content (RWC). In V1, RWC was similar to that in V5 but injury was comparatively low possibly due to low concentration of Na+. The difference between V1 and V2 was significant, either due to the highest concentration of K+ or the lowest reduction in RWC in V2. In V3 and V4, injury was the lowest at all salinity levels and was within the range of values observed earlier for drought tolerance. A significant negative correlation was detected between cellular injury and RWC for V1 and V5 but not for V3 and V4. Cellular injury also showed a significant positive correlation with Na+ and a negative correlation with K+ and grain yield (GY). It appeared that CMS technique is suitable for screening wheat under high salinity levels and for detecting differences that may arise due to cumulative effects of salinity and reduced water contents.

Carbohydrate Metabolism↗
PubMed2002

Esterase as molecular marker for salt tolerance in regenerated plants of rice, Oryza sativa L.

Esterase variation was studied in plants regenerated from callus cultures of four rice (Oryza sativa) varieties, viz. pokkali, which is a moderately salt tolerant variety and three salt sensitive varieties MI 48, annapoorna and jyothi. Variation was studied at tillering stage of plants regenerated from callus culture and germinated from seeds. Somaclonal variants for salt tolerance could be detected using variation in esterase banding pattern and activity.

Biomarkers↗
PubMed2006

The alternative sigma factor RpoH2 is required for salt tolerance in Sinorhizobium sp. strain BL3.

The objectives of this investigation were to isolate the rpoH2 gene encoding an alternative sigma factor from Sinorhizobium sp. BL3 and to determine its role in exopolysaccharide (EPS) synthesis, salt tolerance and symbiosis with Phaseolus lathyroides. The rpoH2 gene of Rhizobium sp. strain TAL1145 is known to be required for EPS synthesis and effective nodulation of Leucaena leucocephala. Three overlapping cosmid clones containing the rpoH2 gene of BL3 were isolated by complementing an rpoH2 mutant of TAL1145 for EPS production. From one of these cosmids, rpoH2 of BL3 was identified within a 3.0-kb fragment by subcloning and sequencing. The cloned rpoH2 gene of BL3 restored both EPS production and nodulation defects of the TAL1145 rpoH2 mutants. Three rpoH2 mutants of BL3 were constructed by transposon-insertion mutagenesis. These mutants of BL3 grew normally in complete or minimal medium and were not defective in EPS synthesis, nodulation and nitrogen fixation, but they failed to grow in salt stress conditions. The mutants complemented with cloned rpoH2 from either BL3 or TAL1145 showed higher levels of salt tolerance than BL3. The expression of rpoH2 in BL3 started increasing during the exponential phase and reached the highest level in the mid-stationary phase. These results indicate that RpoH2 is required for salt tolerance in Sinorhizobium sp. BL3, and it may have additional roles during the stationary phase.

Adaptation, Physiological↗
PubMed2005

Decolorization of azo dyes with high salt concentration by salt-tolerant mixed cultures under anaerobic conditions.

Because the lack of detailed study of biological decolorization in high salt dye wastewater, it is still difficult to evaluate the biological treatment on high-salinity dye wastewater. The experiments were carried out to study the salt-tolerant bacteria, which is useful in the treatment of high-salinity colored wastewater. Simulated wastewater containing 5-150 g/L salt (NaCl) and 50-2000 mg/L Reactive Brilliant Red K-2BP was treated with three salt-tolerant mixed cultures (CAS, TAS, DSAS), which were under a gradually acclimated procedure. With the increase of concentrations of salt and dye, the decolorization became low. The abilities of decolorization of dyes wastewater by three mixed cultures (CAS, TAS, DSAS) were studied, CAS and DSAS mixed cultures showed more active for the treatment of high-salinity colored wastewater than TAS mixed cultures. The results suggested that there might be a simple process for the high salt wastewater treatment, which could be incorporated into conventional activated sludge plants.

Azo Compounds↗
PubMed1979

Salt tolerance of Rhizobium species in broth cultures.

Salt tolerance of five rhizobia strains was examined in broth cultures. Five levels of NaCl concentration were used and the optical density was taken as a measure for the vigour of bacterial growth. Rhizobium leguminosarum and R. meliloti were tolerant to high levels of salinity and growth curves in saline broth showed a similar pattern to the control level. Rhizobium japonicum, cowpea Rhizobium, and R. trifolii were intolerant to salt and showed a strong growth retardation with increasing salt concentration. Growth was inhibited at high levels of salinity. It is suggested that rhizobia sensitivity to salts may be partly responsible to the inhibition of nitrogen fixation by legumes growing under salt stress.

Culture Media↗
PubMed2003

Overexpression of SOD2 increases salt tolerance of Arabidopsis.

The yeast (Schizosaccharomyces pombe) SOD2 (Sodium2) gene was introduced into Arabidopsis under the control of the cauliflower mosaic virus 35S promoter. Transformants were selected for their ability to grow on medium containing kanamycin. Southern- and northern-blot analyses confirmed that SOD2 was transferred into the Arabidopsis genome. There were no obvious morphological or developmental differences between the transgenic and wild-type (wt) plants. Several transgenic homozygous lines and wt plants (control) were evaluated for salt tolerance and gene expression. Overexpression of SOD2 in Arabidopsis improved seed germination and seedling salt tolerance. Analysis of Na+ and K+ contents of the symplast and apoplast in the parenchyma cells of the root cortex and mesophyll cells in the spongy tissue of the leaf showed that transgenic lines accumulated less Na+ and more K+ in the symplast than the wt plants did. The photosynthetic rate and the fresh weight of the transgenic lines were distinctly higher than that of wt plants after NaCl treatment. Results from different tests indicated that the expression of the SOD2 gene promoted a higher level of salt tolerance in vivo in transgenic Arabidopsis plants.

Acclimatization↗
PubMed1989

Differential Histone Acetylation in Alfalfa (Medicago sativa) Due to Growth in NaCl : Responses in Salt Stressed and Salt Tolerant Callus Cultures.

The steady state distribution of histone variant proteins and their modifications by acetylation were characterized in wild type and salinity stress adapted alfalfa (Medicago sativa). Isotopic labeling detected dynamic acetylation at four sites in the histone H3 variants and five sites in histones H4 and H2B. Histone variant H3.2 was the most highly acetylated histone with 25% higher steady state acetylation and a two- to threefold higher acetylation labeling than histone H3.1. Histone phosphorylation was limited to histone variants H1.A, H1.B, and H1.C and to histone H2A.3, which was also acetylated. Histone variant composition was unaffected by cellular exposure to NaCl. Histone acetylation was qualitatively similar in salt-tolerant and salt-sensitive cells under normal growth conditions. However, short term salt stress in salt sensitive cells or continued growth at 1% NaCl in salt tolerant cells led to major increases in the multiacetylated forms of histone H4 and the two variants of histone H3. These changes were more pronounced in the diploid than in the tetraploid alfalfa strains. The increase in multiacetylation of core histones serves as an in vivo reporter suggesting an altered intranuclear ionic environment in the presence of salt. It may also represent an adaptive response in chromatin structure to permit chromatin function in a more saline intranuclear environment.

Journal Article↗