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At least 19 recordsLinked to original sources
PubMed1991

Selenium tolerance, salt tolerance, and selenium accumulation in tall fescue lines.

High levels of soil salinity and Se concentration are coexisting problems in the San Joaquin Valley, California. Tall fescue is a potentially useful crop plant for land management in soils containing elevated concentrations of Se and salinity. Information regarding its physiological mechanism and genetic variation of Se accumulation in this species is scant. Thirteen tall fescue (Festuca arundinacea Schreb.) lines were examined for Se and salt tolerances and Se accumulation in nutrient solution culture. Genetic variation of both Se and salt tolerances was detected among six American cultivars and seven worldwide tall fescue lines. Selenium tolerance and salt tolerance are independent of each other and are negatively correlated with tissue Se and salt concentrations. These relationships suggest that an exclusion mechanism is responsible for the tolerance. This diversity of Se and salt tolerance and Se accumulation among the tall fescue lines is important for the application of this species for land management.

Genotype↗
PubMed2002

The Arabidopsis salt overly sensitive 4 mutants uncover a critical role for vitamin B6 in plant salt tolerance.

Salt stress is a major environmental factor influencing plant growth and development. To identify salt tolerance determinants, a genetic screen for salt overly sensitive (sos) mutants was performed in Arabidopsis. We present here the characterization of sos4 mutants and the positional cloning of the SOS4 gene. sos4 mutant plants are hypersensitive to Na(+), K(+), and Li(+) ions. Under NaCl stress, sos4 plants accumulate more Na(+) and retain less K(+) compared with wild-type plants. SOS4 encodes a pyridoxal kinase that is involved in the biosynthesis of pyridoxal-5-phosphate, an active form of vitamin B6. The expression of SOS4 cDNAs complements an Escherichia coli mutant defective in pyridoxal kinase. Supplementation of pyridoxine but not pyridoxal in the growth medium can partially rescue the sos4 defect in salt tolerance. SOS4 is expressed ubiquitously in all plant tissues. As a result of alternative splicing, two transcripts are derived from the SOS4 gene, the relative abundance of which is modulated by development and environmental stresses. Besides being essential cofactors for numerous enzymes, as shown by pharmacological studies in animal cells, pyridoxal-5-phosphate and its derivatives are also ligands for P2X receptor ion channels. Our results demonstrate that pyridoxal kinase is a novel salt tolerance determinant important for the regulation of Na(+) and K(+) homeostasis in plants. We propose that pyridoxal-5-phosphate regulates Na(+) and K(+) homeostasis by modulating the activities of ion transporters.

Adaptation, Physiological↗
PubMed2001

Identification of two loci in tomato reveals distinct mechanisms for salt tolerance.

Salt stress is one of the most serious environmental factors limiting the productivity of crop plants. To understand the molecular basis for salt responses, we used mutagenesis to identify plant genes required for salt tolerance in tomato. As a result, three tomato salt-hypersensitive (tss) mutants were isolated. These mutants defined two loci and were caused by single recessive nuclear mutations. The tss1 mutant is specifically hypersensitive to growth inhibition by Na(+) or Li(+) and is not hypersensitive to general osmotic stress. The tss2 mutant is hypersensitive to growth inhibition by Na(+) or Li(+) but, in contrast to tss1, is also hypersensitive to general osmotic stress. The TSS1 locus is necessary for K(+) nutrition because tss1 mutants are unable to grow on a culture medium containing low concentrations of K(+). Increased Ca(2)+ in the culture medium suppresses the growth defect of tss1 on low K(+). Measurements of membrane potential in apical root cells were made with an intracellular microelectrode to assess the permeability of the membrane to K(+) and Na(+). K(+)-dependent membrane potential measurements indicate impaired K(+) uptake in tss1 but not tss2, whereas no differences in Na(+) uptake were found. The TSS2 locus may be a negative regulator of abscisic acid signaling, because tss2 is hypersensitive to growth inhibition by abscisic acid. Our results demonstrate that the TSS1 locus is essential for K(+) nutrition and NaCl tolerance in tomato. Significantly, the isolation of the tss2 mutant demonstrates that abscisic acid signaling is also important for salt and osmotic tolerance in glycophytic plants.

Abscisic Acid↗
PubMed2002

Salt-tolerant mutants in glycophytic salinity response (GSR) genes in Catharanthus roseus.

The periwinkle Catharanthus roseus shares glycophytic properties of crop plants. To contribute towards an understanding of the glycophytic response to salinity, large populations of M(2) seeds having an origin in nitroso-methyl urea and ethyl methane sulphonate treatments were screened for germination with 250 mM of NaCl. Out of the nine mutant lines so recovered, which tolerated salt stress due to loss of the normal glycophytic salinity response ( GSR), the characteristics of six gsr mutants are reported here. All six, gsr-1 to gsr-6, differed from the wild-type in both seedling and adult-plant morphological characters beside being salt tolerant. The mutations in them were inherited as monogenic recessive alleles at the corresponding wild-type loci. The trans-complementation tests revealed that the gsr-1 to gsr-6 mutants specified six complementation groups. The mutant seedlings generally accumulated more proline and glycine betaine, constitutively, than the wild-type. The mutant plants transpired lower amounts of water and accumulated higher amounts of proline under drought stress. It was inferred that the products of the six GSR genes defined here are involved in the regulation of salt stress, as well as cell division, developmental and/or morphogenetic pathway(s), in C. roseus.

Adaptation, Physiological↗
PubMed1991

The k/na selectivity of a cation channel in the plasma membrane of root cells does not differ in salt-tolerant and salt-sensitive wheat species.

The characteristics of cation outward rectifier channels were studied in protoplasts from wheat root (Triticum aestivum L. and Triticum turgidum L.) cells using the patch clamp technique. The cation outward rectifier channels were voltage-dependent with a single channel conductance of 32 +/- 1 picosiemens in 100 millimolar KCl. Whole-cell currents were dominated by the activity of the cation outward rectifiers. The time- and voltage-dependence of these currents was accounted for by the summed behavior of individual channels recorded from outside-out detached patches. The K(+)/Na(+) permeability ratio of these channels was measured in a salt-sensitive and salt-tolerant genotype of wheat that differ in rates of Na(+) accumulation, using a voltage ramp protocol on protoplasts in the whole-cell configuration. Permeability ratios were calculated from shifts in reversal potentials following ion substitutions. There were no significant differences in the K(+)/Na(+) permeability ratios of these channels in root cells from either of the two genotypes tested. The permeability ratio for K(+)/Cl(-) was greater than 50:1. The K(+)/Na(+) permeability ratio averaged 30:1, which is two to four times more selective than the same type of channel in guard cells and suspension culture cells. Lowering the Ca(2+) concentration in the bath solution to 0.1 millimolar in the presence of 100 millimolar Na(+) had no significant effect on the K(+)/Na(+) permeability ratios of the channel. It seems unlikely that the mechanism of salt tolerance in wheat is based on differences in the K(+)/Na(+) selectivity of these channels.

Journal Article↗
PubMed2006

An ABRE-binding factor, OSBZ8, is highly expressed in salt tolerant cultivars than in salt sensitive cultivars of indica rice.

BACKGROUND: The bZIP class Abscisic acid Responsive Element (ABRE)-binding factor, OSBZ8 (38.5 kD) has been considered to regulate ABA-mediated transcription in the suspension cultured cells of japonica rice. Still, nothing is known about the expression of OSBZ8 at protein level in vegetative tissue of salt sensitive and salt tolerant rice plants. In our previous study, Electrophoretic Mobility Shift Assay (EMSA) of [32P]ABRE-DNA and nuclear extracts prepared from the lamina of Pokkali rice plants has detected the presence of an ABRE-binding factor. Northern analysis has also detected salinity stress induced accumulation of transcripts for bZIP class of factor. Therefore, OSBZ8 was considered to play an important role in the regulation of transcription in the vegetative tissue of rice. The aim of this study is to find out whether OSBZ8 has any role in regulating the NaCl-stress induced gene expression in vegetative tissue and whether the expression of OSBZ8 factor directly correlates with the stress tolerance of different varieties of indica type rice. RESULTS: Northern analysis of total RNA from roots and lamina of salt-sensitive M-I-48 and salt-tolerant Nonabokra, when probed with the N-terminal unique region of OSBZ8 (OSBZ8p, without the highly conserved basic region), a transcript of 1.3 kb hybridized and its level was much higher in tolerant cultivar. EMSA with Em1a, the strongest ABA Responsive Element till reported from the upstream of EmBP1, and the nuclear extracts from laminar tissue of untreated and salt-treated seedlings of three salt sensitive, one moderately sensitive and two salt tolerant indica rice cultivars showed specific binding of nuclear factor to ABRE element. Intensity of binding was low and inducible in salt sensitive rice cultivars while high and constitutive in salt tolerant cultivars. EMSA with 300 bp 5'upstream region of Rab16A gene, a well known salt stress and ABA-inducible gene of rice, showed formation of two complexes, again very weak in salt sensitive and strong in salt tolerant rice cultivar. CONCLUSION: The bZIP factor OSBZ8 was found to be present in the ABRE-DNA: protein complex as shown by the supershift of the complex by the purified antiserum raised against OSBZ8p. Treatment of the seedlings with NaCl was found to enhance the complex formation, suggesting the regulation of OSBZ8 gene at both transcriptional and post-translational steps. Comparative EMSA with different varieties of rice suggests a positive correlation with the expression pattern of OSBZ8 and salt tolerance in rice cultivars.

Abscisic Acid↗
PubMed2006

Introgression of a novel salt-tolerant L-myo-inositol 1-phosphate synthase from Porteresia coarctata (Roxb.) Tateoka (PcINO1) confers salt tolerance to evolutionary diverse organisms.

We have previously demonstrated that introgression of PcINO1 gene from Porteresia coarctata (Roxb.) Tateoka, coding for a novel salt-tolerant L-myo-inositol 1-phosphate synthase (MIPS) protein, confers salt tolerance to transgenic tobacco plants (Majee, M., Maitra, S., Dastidar, K.G., Pattnaik, S., Chatterjee, A., Hait, N.C., Das, K.P. and Majumder, A.L. (2004) A novel salt-tolerant L-myo-inositol-1-phosphate synthase from Porteresia coarctata (Roxb.) Tateoka, a halophytic wild rice: molecular cloning, bacterial overexpression, characterization, and functional introgression into tobacco-conferring salt-tolerance phenotype. J. Biol. Chem. 279, 28539-28552). In this communication we have shown that functional introgression of the PcINO1 gene confers salt-tolerance to evolutionary diverse organisms from prokaryotes to eukaryotes including crop plants albeit to a variable extent. A direct correlation between unabated increased synthesis of inositol under salinity stress by the PcINO1 gene product and salt tolerance has been demonstrated for all the systems pointing towards the universality of the application across evolutionary divergent taxa.

Adaptation, Physiological↗
PubMed1992

Characterization of salt-tolerant and salt-sensitive mutants of Rhizobium leguminosarum biovar viciae strain C1204b.

Spontaneous mutants of Rhizobium leguminosarum biovar viciae strain C1204b were selected for their ability to tolerate 0.2 M NaCl, a growth-inhibiting level of salt for the parental strain. Transposon-mediated salt-sensitive mutants of strain C1204b were screened for their inability to grow in 0.08 M NaCl. Quantitation of the free-amino acid pools in the mutants grown in NaCl revealed a dramatic increase in glutamine, serine, glutamate and proline, and to a lesser extent alanine and glycine in the salt-tolerant mutants in comparison with the parental strain exposed to NaCl; but only glutamate and proline increased in the salt-sensitive mutants under NaCl stress. Extracellular polysaccharide levels were quantitated for the salt-tolerant mutants and determined to be approximately two-fold higher than for the parental strain. Although the mutations that occurred in the NaCl-tolerant and NaCl-sensitive strains did not interfere with nodule formation, no nitrogenase activity could be observed in the NaCl tolerant mutants as evaluated by acetylene reduction.

Amino Acids↗
PubMed2001

Transgenic salt-tolerant tomato plants accumulate salt in foliage but not in fruit.

Transgenic tomato plants overexpressing a vacuolar Na+/H+ antiport were able to grow, flower, and produce fruit in the presence of 200 mM sodium chloride. Although the leaves accumulated high sodium concentrations, the tomato fruit displayed very low sodium content. Contrary to the notion that multiple traits introduced by breeding into crop plants are needed to obtain salt-tolerant plants, the modification of a single trait significantly improved the salinity tolerance of this crop plant. These results demonstrate that with a combination of breeding and transgenic plants it could be possible to produce salt-tolerant crops with far fewer target traits than had been anticipated. The accumulation of sodium in the leaves and not in the fruit demonstrates the utility of such a modification in preserving the quality of the fruit.

Blotting, Western↗
PubMed2026

CaMYB121-CaABF2 negative feedback loop modulates CaNHX2 expression to confer salt tolerance in pepper.

Salt stress is a major abiotic factor that severely restricts pepper (Capsicum annuum) production. Although abscisic acid (ABA) is vital for salt tolerance, the transcriptional regulatory networks governing ABA-mediated salt defense remain largely unknown. Here, we uncovered a negative feedback loop between CaMYB121 and CaABF2.1/2 that modulates the expression of CaNHX2.1/2/3, thereby enhancing salt tolerance in pepper plants. RNA-seq analysis revealed that CaMYB121 displayed an expression pattern consistent with that of CaNHX2 after salt treatment. Silencing CaMYB121 markedly reduced salt tolerance and inhibited root growth. Mechanistically, CaMYB121 directly binds to the CaNHX2 promoter to activate transcription, thereby promoting salt resilience. Salt stress also robustly triggered ABA signaling genes, with CaABF2.1/2 displaying expression patterns closely mirroring those of CaMYB121. Transient silencing of CaABF2.1/2 results in phenotypes similar to those observed with CaMYB121 suppression. Notably, CaMYB121 activates CaABF2.1/2 transcription by binding to its promoters, whereas CaABF2.1/2 represses CaMYB121 expression by directly targeting its promoter, forming a self-regulating feedback loop that prevents excessive defense activation. Collectively, our findings reveal a CaMYB121-CaABF2 feedback circuit that dynamically balances growth and defense to optimize salt tolerance in pepper plants.

Salt Tolerance↗
PubMed2002

Involvement of Nst1p/YNL091w and Msl1p, a U2B'' splicing factor, in Saccharomyces cerevisiae salt tolerance.

Cell tolerance to salt stress depends on many physiological functions, including the best characterized of osmotic adjustment, ion transport and sodium-sensitive sulphate metabolism. From a screening designed to identify novel determinants of salt tolerance we have isolated the YNL091w gene, probably an Ascomycete-specific gene encoding a protein of unknown function. This gene negatively affects salt tolerance and therefore has been designated NST1. The salt tolerance mechanism of nst1 mutants is novel because it is not related to osmoregulation, altered cation accumulation or sulphate metabolism. Genome-wide two-hybrid analysis has suggested that Nst1p interacts with the splicing factor Msl1p and, accordingly, the impact of NST1 on salt tolerance is dependent on a functional MSL1 gene. Loss of MSL1 and NST1 function has pleiotropic phenotypes including increased sensitivity to divalent cations (manganese and zinc) and to caffeine (a cell wall-weakening agent). On the other hand, msl1 mutants but not nst1 mutants are sensitive to thiabendazole (a microtubule-destabilizing agent) and to osmotic stress.

Amino Acid Sequence↗
PubMed1989

A Comparison of the Effect of Salt on Polypeptides and Translatable mRNAs in Roots of a Salt-Tolerant and a Salt-Sensitive Cultivar of Barley.

The effect of salt stress on polypeptide and mRNA levels in roots of two barley (Hordeum vulgare L.) cultivars differing in salt tolerance (cv CM 72, tolerant; cv Prato, sensitive) was analyzed using two-dimensional polyacrylamide gel electrophoresis. Preliminary experiments indicated that germination of Prato was inhibited significantly in the presence of NaCl, but growth of the surviving Prato seedlings was not substantially different from that of CM 72. Fluorographs of two-dimensional gels containing in vivo labeled polypeptides or in vitro translation products were computer analyzed to identify and quantitate changes that resulted when plants were grown in the presence of 200 millimolar NaCl for 6 days. The patterns of in vivo labeled polypeptides and in vitro products of CM 72 and Prato were qualitatively the same. Salt caused quantitative changes in numerous polypeptides and translatable mRNAs, but, overall, the changes were relatively small. Salt did not induce the synthesis of unique polypeptides or translatable mRNAs and did not cause any to disappear. Because of the similarities of the two cultivars with respect to growth and polypeptide patterns and the slight changes in polypeptide and translation product levels caused by salt, specific polypeptides or translatable mRNAs that are related to salt tolerance in barley could not be identified.

Journal Article↗
PubMed2004

A novel salt-tolerant L-myo-inositol-1-phosphate synthase from Porteresia coarctata (Roxb.) Tateoka, a halophytic wild rice: molecular cloning, bacterial overexpression, characterization, and functional introgression into tobacco-conferring salt tolerance phenotype.

l-myo-Inositol-1-phosphate synthase (EC 5.5.1.4, MIPS), an evolutionarily conserved enzyme protein, catalyzes the synthesis of inositol, which is implicated in a number of metabolic reactions in the biological kingdom. Here we report on the isolation of the gene (PINO1) for a novel salt-tolerant MIPS from the wild halophytic rice, Porteresia coarctata (Roxb.) Tateoka. Identity of the PINO1 gene was confirmed by functional complementation in a yeast inositol auxotrophic strain. Comparison of the nucleotide and deduced amino acid sequences of PINO1 with that of the homologous gene from Oryza sativa L. (RINO1) revealed distinct differences in a stretch of 37 amino acids, between amino acids 174 and 210. Purified bacterially expressed PINO1 protein demonstrated a salt-tolerant character in vitro compared with the salt-sensitive RINO1 protein as with those purified from the native source or an expressed salt-sensitive mutant PINO1 protein wherein amino acids 174-210 have been deleted. Analysis of the salt effect on oligomerization and tryptophan fluorescence of the RINO1 and PINO1 proteins revealed that the structure of PINO1 protein is stable toward salt environment. Furthermore, introgression of PINO1 rendered transgenic tobacco plants capable of growth in 200-300 mm NaCl with retention of approximately 40-80% of the photosynthetic competence with concomitant increased inositol production compared with unstressed control. MIPS protein isolated from PINO1 transgenics showed salt-tolerant property in vitro confirming functional expression in planta of the PINO1 gene. To our knowledge, this is the first report of a salt-tolerant MIPS from any source.

Amino Acid Sequence↗
PubMed1992

Salt tolerance and glycerol accumulation of a respiration-deficient mutant isolated from the petite-negative, salt-tolerant yeast Zygosaccharomyces rouxii.

A respiration-deficient (RD) mutant was isolated from the petite-negative, salt-tolerant yeast Zygosaccharomyces rouxii. One strain among sixteen glycerol-non-utilizing mutants exhibited vigorous liberation of CO2 but no uptake of O2. Furthermore, this strain lacked cytochrome aa3 and had a reduced level of cytochrome b. The few mitochondria found in cells of this strain contained few or no cristae. Salt tolerance and intracellular accumulation of glycerol by the RD strain were almost equal to that of the wild-type strain in media containing NaCl up to 2.5 M. In media with more than 3 M NaCl, the growth of the RD mutant was retarded and the intracellular accumulation of glycerol was depressed in spite of ample production.

Adaptation, Biological↗
PubMed1997

Transfer of the yeast salt tolerance gene HAL1 to Cucumis melo L. cultivars and in vitro evaluation of salt tolerance.

An Agrobacterium-mediated gene transfer method for production of transgenic melon plants has been optimized. The HAL1 gene, an halotolerance gene isolated from yeast, was inserted in a chimaeric construct and joined to two marker genes: a selectable-neomycin phosphotransferase-II (nptII)-, and a reporter-beta-glucuronidase (gus)-. The entire construct was introduced into commercial cultivars of melon. Transformants were selected for their ability to grow on media containing kanamycin. Transformation was confirmed by GUS assays, PCR analysis and Southern hybridization. Transformation efficiency depended on the cultivar, selection scheme used and the induction of vir-genes by the addition of acetosyringone during the cocultivation period. The highest transformation frequency, 3% of the total number of explants cocultivated, was obtained with cotyledonary explants of cv. 'Pharo'. Although at a lower frequency (1.3%), we have also succeeded in the transformation of leaf explants. A loss of genetic material was detected in some plants, and results are in accordance with the directional model of T-DNA transfer. In vitro cultured shoots from transgenic populations carrying the HAL1 gene were evaluated for salt tolerance on shoot growth medium containing 10 gl-1 NaCl. Although root and vegetative growth were reduced, transgenic HAL1-positive plants consistently showed a higher level of tolerance than control HAL1-negative plants.

Acetophenones↗
PubMed2006

Na+/K+ selectivity of leaf sheath in wheat cultivars differing in salt tolerance.

A salt-tolerant wheat cultivar (DK961) and a salt-sensitive one (LM15) were exposed to 200 mmol/L NaCl for 3 d to study selectivity in transport of K(+) and Na(+) of the leaf sheath. Na(+) content of leaf sheath and K(+) content of leaf blade of DK961 were significantly higher than those of LM15, which led to a lower Na(+)/K(+) ratio of leaf blade of DK961 than that of LM15. These results suggested that leaf sheath of DK961 had much stronger abilities of limiting Na(+) transport and allowing K(+) transport from leaf sheath to leaf blade than that of LM15 to maintain lower Na(+)/K(+) ratio of leaf blade under NaCl stress, indicating that leaf sheath may play an important role in wheat salt tolerance.

Biological Transport↗
PubMed2026

Genome-wide identification of CXE gene family in soybean and functional characterization of GmCXE31 in lipid biosynthesis and salt tolerance.

GmCXE31 negatively regulates salt tolerance and lipid synthesis in soybean, and the cxe31-edited lines improve soybean yield and seed quality. Carboxylesterases (CXEs), as essential lipid hydrolases of the α/β-hydrolase fold superfamily, are critical for plant stress responses, hormone signaling and secondary metabolism. The key candidate gene GmCXE31 was previously identified in our laboratory through a genome‑wide association study (GWAS) of soybean lipid‑related traits. In the present study, we further identified 60 GmCXE family genes in soybean. Phylogenetic analysis clustered them into 11 conserved subfamilies. Cis-acting element analysis showed their promoters are enriched with elements related to abiotic stress, growth and hormone signaling, suggesting potential roles in soybean development and stress adaptation. GmCXE31 is highly expressed in seedling roots and responsive to strigolactones (SLs) and salt stress. Functional assays revealed that GmCXE31 negatively regulates soybean salt tolerance: its overexpression reduced salt tolerance in Arabidopsis and soybean under 150 mM NaCl stress, while its knockout enhanced this trait. Lipid profiling revealed GmCXE31-edited lines had higher seed oil content, elevated oleic/linoleic acid ratio and lower saturated fatty acid proportion, which was achieved by regulating lipid synthesis-related genes like GmNFYA. Agronomic trait analysis showed GmCXE31-edited lines had increased nodule number, plant height and single-plant yield at maturity, with opposite phenotypes in overexpression lines. In conclusion, this study elucidates the multifaceted roles of GmCXE31 in coordinating soybean salt tolerance, lipid metabolism and agronomic traits, providing theoretical and genetic resources for salt-tolerant and high-quality soybean molecular breeding.

Glycine max↗