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At least 109 records · Page 6Linked to original sources

PubMed2005

A rice quantitative trait locus for salt tolerance encodes a sodium transporter.

Many important agronomic traits in crop plants, including stress tolerance, are complex traits controlled by quantitative trait loci (QTLs). Isolation of these QTLs holds great promise to improve world agriculture but is a challenging task. We previously mapped a rice QTL, SKC1, that maintained K(+) homeostasis in the salt-tolerant variety under salt stress, consistent with the earlier finding that K(+) homeostasis is important in salt tolerance. To understand the molecular basis of this QTL, we isolated the SKC1 gene by map-based cloning and found that it encoded a member of HKT-type transporters. SKC1 is preferentially expressed in the parenchyma cells surrounding the xylem vessels. Voltage-clamp analysis showed that SKC1 protein functions as a Na(+)-selective transporter. Physiological analysis suggested that SKC1 is involved in regulating K(+)/Na(+) homeostasis under salt stress, providing a potential tool for improving salt tolerance in crops.

Base Sequence↗

PubMed1998

Mutation of a gene encoding a putative glycoprotease leads to reduced salt tolerance, altered pigmentation, and cyanophycin accumulation in the cyanobacterium Synechocystis sp. strain PCC 6803.

The salt-sensitive mutant 549 of the cyanobacterium Synechocystis sp. strain PCC 6803 was genetically and physiologically characterized. The mutated site and corresponding wild-type site were cloned and partially sequenced. The genetic analysis revealed that during the mutation about 1.8 kb was deleted from the chromosome of mutant 549. This deletion affected four open reading frames: a gcp gene homolog, the psaFJ genes, and an unknown gene. After construction of mutants with single mutations, only the gcp mutant showed a reduction in salt tolerance comparable to that of the initial mutant, indicating that the deletion of this gene was responsible for the salt sensitivity and that the other genes were of minor importance. Besides the reduced salt tolerance, a remarkable change in pigmentation was observed that became more pronounced in salt-stressed cells. The phycobilipigment content decreased, and that of carotenoids increased. Investigations of changes in the ultrastructure revealed an increase in the amount of characteristic inclusion bodies containing the high-molecular-weight nitrogen storage polymer cyanophycin (polyaspartate and arginine). The salt-induced accumulation of cyanophycin was confirmed by chemical estimations. The putative glycoprotease encoded by the gcp gene might be responsible for the degradation of cyanophycin in Synechocystis. Mutation of this gene leads to nitrogen starvation of the cells, accompanied by characteristic changes in pigmentation, ultrastructure, and salt tolerance level.

Amino Acid Sequence↗

PubMed2006

[Introduce Tagsk1 into salt-sensitive callus to improve the capacity of salt-tolerance by micropartical bombardment].

The Tagsk1 (Triticum asetium L. glycogen synthase kinase 1) gene derived from the genome of wheat salt-tolerance mutant RH8706-49 was cloned by PCR. The special primers designed according to full length cDNA sequence of Tagsk1 (AF525086). A binary expression vector pBI121-gsk1 containing Gus and Tagsk1 was constructed. And pBI121-gsk1 was introduced into the callus induced from mature embryos of salt-sensitive wheat H8706-34 and cv. China Spring by particle bombardment. The transformed callus were screened by Kanamycin and 0.5% NaCl. The salt-tolerance callus were obtained, which showed higher ability of salt-tolerance and could diffirentiate roots and buds on the medium containing 0.5% NaCl.

Adaptation, Physiological↗

PubMed1982

Salt tolerance in crop plants monitored by chlorophyll fluorescence in vivo.

The potential of measurements of chlorophyll fluorescence in vivo to detect cellular responses to salinity and degrees of salt stress in leaves was investigated for three crop plants. Sugar beet (Beta vulgaris L.) (salt tolerant), sunflower (Helianthus annuus L.) (moderately salt tolerant), and bean (Phaseolus Vulgaris L. cv Canadian Wonder) (salt intolerant) were grown in pots and watered with mineral nutrient solution containing 100 millimolar NaCl. The fast rise in variable chlorophyll fluorescence yield that is correlated with photoreduction of photosystem II acceptors increased in leaves of sugar beet plants treated with salt suggesting stimulation of photosystem II activity relative to photosystem I. In sunflower, this fast rise was depressed by approximately 25% and the subsequent slow rate of quenching of the chlorophyll fluorescence was stimulated. These differences were more marked in the older mature leaves indicating an increasing gradient of salt response down the plant. The salt effect in vivo was reversible since chloroplasts isolated from mature leaves of salt-treated and control sunflower plants gave similar photosystem II activities. Unlike in sugar beet and sunflower, leaves of salt-treated bean progressively lost chlorophyll. The rate of slow quenching of chlorophyll fluorescence decreased indicating development of a partial block after photosystem II and possible initial stimulation of photosystem II activity. With further loss of chlorophyll photosystem II activity declined. It was concluded that measurements of chlorophyll fluorescence in vivo can provide a rapid means of detecting salt stress in leaves, including instances where photosynthesis is reduced in the absence of visible symptoms. The possible application to screening for salt tolerance is discussed.

Journal Article↗

PubMed2002

[Research progress in salt tolerance genes of SOS in Arabidopsis thaliana].

The soil salination is a significant abiotic stress for agricultural production and ecological environment. The research on salt tolerance represents an important part for basic plant biology. Genetic analysis of salt tolerance genes in Arabidopsis has become a central issue in this research areas. In recent years, efforts from some laboratories in the world have led to some significant progresses in this field. In this paper, we will review the progress in salt tolerance genes SOS (salt overly sensitive): SOS1,SOS2 and SOS3.

English Abstract↗

PubMed2002

[Molecular markers and its clone for salt tolerance gene in wheat].

Genetic and RAPD analysis were studied among [4] individuals in F2 segregated population originating from a cross between wheat cultivator Nongda 85021 (female parent, salt sensitive) and Chadian Red (male parent, salt tolerant). For genetic analysis and chi-square test gave a good fit of 1:2:1 ratio showing that one major gene was controlling the salt tolerant character in Chadian Red. DNA of F2 population was extracted to develop tolerant and sensitive gene pools, respectively, based the BSA (Bulked Segregate Analysis). By RAPD (Randomly Amplified Polymorphic DNAs), 520 random primers were used to amplify the two types of gene pools. Only primer OPZ09 was found to be polymorphic with a fragment of 590 bp in the two parents, F1 and F2 populations. So, the specific fragment OPZ09-590 was, a RAPD marker linked to salt tolerance gene in Chadian Red. By the software JOINMAP (Version 1.4), the recombination was 5.674% and the linking distance was 6.557 cM. OPZ09-590 was extracted from the agarose and mixed with pUCm-T vector, then the vector was transferred into JM109. The clone was determined 591 bp after being sequenced. It indicated that the RAPD marker of salt tolerance gene in Chadian Red was OPZ09-591.

Base Sequence↗

PubMed1997

Comparison between the polypeptide profile of halophilic bacteria and salt tolerant plants.

Changes in the polypeptide profile induced by salt stress in halotolerant and halophilic bacteria, isolated from the Atacama desert (northern Chile), were compared with those in the cotyledons of Prosopis chilensis (Leguminoseae) seedlings, a salt tolerant plant. SDS-PAGE analyses show the presence of four predominant polypeptides, with molecular weights around 78, 70, 60 and 44 kDa respectively, both in bacteria and in cotyledons from P. chilensis seedlings raised under salt stress conditions. Moreover, the 60 and 44 kDa polypeptides seem to be salt responsive, since their concentration increases with increasing NaCl in the growth medium. Our results suggest a common mechanism for salt tolerance in prokaryotes and in eukaryotes.

Adaptation, Physiological↗

PubMed2006

Overexpression of Arabidopsis thaliana LTL1, a salt-induced gene encoding a GDSL-motif lipase, increases salt tolerance in yeast and transgenic plants.

Genes involved in the mechanisms of plant responses to salt stress may be used as biotechnological tools for the genetic improvement of salt tolerance in crop plants. This would help alleviate the increasing problem of salinization of lands cultivated under irrigation in arid and semi-arid regions. We have isolated a novel halotolerance gene from Arabidopsis thaliana, A. thaliana Li-tolerant lipase 1 (AtLTL1), on the basis of the phenotype of tolerance to LiCl conferred by its expression in yeast. AtLTL1 encodes a putative lipase of the GDSL-motif family, which includes bacterial and a very large number of plant proteins. In Arabidopsis, AtLTL1 expression is rapidly induced by LiCl or NaCl, but not by other abiotic stresses. Overexpression of AtLTL1 increases salt tolerance in transgenic Arabidopsis plants, compared to non-transformed controls, allowing germination of seeds in the presence of toxic concentrations of LiCl and NaCl, and stimulating vegetative growth, flowering and seed set in the presence of NaCl. These results clearly point to a role of AtLTL1 in the mechanisms of salt tolerance. In addition, we show that AtLTL1 expression is also activated, although only transiently, by salicylic acid (SA), suggesting that the lipase could also be involved in defence reactions against pathogens.

Adaptation, Physiological↗

PubMed1999

Two putative MAP kinase genes, ZrHOG1 and ZrHOG2, cloned from the salt-tolerant yeast Zygosaccharomyces rouxii are functionally homologous to the Saccharomyces cerevisiae HOG1 gene.

The salt-tolerant yeast Zygosaccharomyces rouxii can adjust its osmotic balance when responding to osmotic shock by accumulating glycerol as the compatible osmolyte. However, the mechanism of glycerol production in Z. rouxii cells and its genetic regulation remain to be elucidated. Two putative mitogen-activated protein (MAP) kinase genes, ZrHOG1 and ZrHOG2, were cloned from Z. rouxii by their homology with HOG1 from Saccharomyces cerevisiae. The deduced amino acid sequences of ZrHog1p and ZrHog2p indicated close homology to that of Hog1p and contained a TGY motif for phosphorylation by MAP kinase kinase. When ZrHOG1 or ZrHOG2 was expressed in an S. cerevisiae hog1delta null mutant, the salt tolerance and osmotic tolerance characteristics of wild-type S. cerevisiae were restored. In addition, the aberrant cell morphology and low glycerol content of the hog1delta null mutant were corrected, indicating that ZrHog1p and ZrHog2p have functions similar to Hog1p. While the transcription of the glycerol-3-phosphate dehydrogenase gene (GPD1) of the ZrHOG1-harbouring S. cerevisiae mutant was similar to that of wild-type S. cerevisiae, the ZrHOG2-harbouring strain showed prolonged GPD1 transcription. Both Zrhog1delta and Zrhog2delta Z. rouxii null mutants showed a decrease in salt tolerance compared to the wild-type strain. The present study suggested the presence of a high-osmolarity glycerol response (HOG) pathway in Z. rouxii similar to that elucidated in S. cerevisiae. Two putative MAP kinase genes in Z. rouxii appeared to be significant in either osmotic regulation or ion homeostasis.

Amino Acid Sequence↗

PubMed2002

Overexpression of a plasma membrane Na+/H+ antiporter gene improves salt tolerance in Arabidopsis thaliana.

High concentrations of Na+ in saline soils inhibit plant growth and reduce agricultural productivity. We report here that CaMV 35S promoter driven overexpression of the Arabidopsis thaliana SOS1 gene, which encodes a plasma membrane Na+/H+ antiporter, improves plant salt tolerance in A. thaliana. Transgenic plants showed substantial upregulation of SOS1 transcript levels upon NaCl treatment, suggesting post-transcriptional control of SOS1 transcript accumulation. In response to NaCl treatment, transgenic plants overexpressing SOS1 accumulated less Na+ in the xylem transpirational stream and in the shoot. Undifferentiated callus cultures regenerated from the transgenic plants were also more tolerant of salt stress, which was correlated with reduced Na+ content in the transgenic cells. These results show that improved salt tolerance could be achieved by limiting Na+ accumulation in plant cells.

Arabidopsis↗

PubMed2000

Male and female gametophyte selection of barley for salt tolerance.

The contribution of the gametophyte in the inheritance of salt tolerance was studied by crossing F3 and BC1 hybrids of the tolerant cultivars Rannii 1 and Pirkka with the sensitive cultivar K-30356. The third generation shows that the progenies of heterozygous plants grown in saline conditions show elevated salinity tolerance. Again, a comparison of the BC1 hybrid progenies shows that the male and female gametophytes contribute to the inheritance of salt tolerance. Gametic selection is maximally efficient during the formation of the female gametophyte and the germination of pollen grains on the stigma.

Alleles↗

PubMed1981

Repair of salt tolerance and recovery of lost D-alanine and magnesium following sublethal heating of Staphylococcus aureus are independent events.

Sublethal heating of Staphylococcus aureus S6 in potassium phosphate buffer caused loss of salt tolerance, D-alanine, and magnesium. During incubation in rich complex media all three of the damaged sites were repaired. Repair occurred more slowly but went to completion in a dilute synthetic medium (DSM), free of D-ala. DSM plus penicillin or D-cycloserine allowed repair of salt tolerance but recovery of normal levels of D-ala or Mg was prevented. When DSM-repaired cells were cultured into fresh rich medium they grew rapidly after a short lag. Cells which had acquired their salt tolerance in DSM plus cycloserine and were D-ala and Mg deficient grew slowly and had a lag of 3 h. We suggest that heat damage has two separate primary targets in S. aureus cells: the membrane, which is manifested by loss of salt tolerance, and a second site, possibly teichoic acids, manifested by loss of D-ala and Mg.

Alanine↗

PubMed2001

[Selection and identification of salt tolerant line of sainfoin from the seeds of first post-flight plants].

Seeds of sainfoin (Onobrychis vicaefolia Scop.) were carried in the recoverable satellite 940703 and recovered from earth orbit from China in 1994. The progeny seeds were obtained by producing in field. The salt tolerant calluses were selected by screening seedling and callus on 1.5% NaCl-containing medium, reviving growth on NaCl- free medium and selecting callus on 1.2% NaCl-containing medium. The salt tolerant line callus maintained the normal ability to regenerate plant. The salt tolerant line callus exhibited cross-resistance to PEG stress. The variant appeared higher efficiency than control to accumulate proline under salt stress, however, under nonstress condition it had lower proline level than control, which suggested that the higher efficiency to synthesize proline under stress condition may be more important than higher level in tissue under nonstress condition. The mechanism of proline synthesis in the selected callus was considered to result from the alteration in gene sensitivity to water regulation at transcription level. Acrylamide gradient electrophoresis showed that new isoenzyme form with MW 175 kD and 75 kD of superoxide dismutase and esterase respectively appeared in salt torlerant callus. It was indicated that the combination of space mutagenesis with tissue culture could be used for the selection of salt tolerant sainfoin line in vitro.

Adaptation, Physiological↗

PubMed2001

[Cloning of gene related to salt tolerance from Sinorhizobium fredii RT19 and its expression in Escherichia coli].

A 4.4 kb DNA fragment related to salt tolerance containing three open reading frames was isolated from the gene library of S. fredii strain RT19. By subcloning and functional analysis, only ORF2 related to salt tolerance was obtained. The ORF2 was ligated to expression vectors pThioHisA, B and C, respectively, and recombinant expression vectors pGA, pGB and pGC containing 1.5 kb DNA fragment related to salt tolerance were constructed. These recombinant expression vectors were transformed into E. coli DH5 alpha. Inducing by IPTG and analyzing with SDS-PAGE, it was found that the fusion protein encoded by pGC was expressed, and its molecular weight was equal to the sum of thioredoxin encoded by trxA and ORF2 putative protein molecular weight. The Western blot demonstrated that the target gene was successfully expressed in E. coli.

Cloning, Molecular↗

PubMed2000

Characterization of salt-tolerant mutant for enhancement of L-threonine production in Escherichia coli.

Escherichia coli strain HS3, metabolically engineered to have Met(-), AHV(r), Ile(L) and AEC(r) characteristics, produced 58.0 g/l of L-threonine, but it was neither salt-tolerant nor osmotolerant; and the growth and threonine production of the strain were severely inhibited both by the addition of NaCl with a concentration higher than 2% and by the presence of glucose with a concentration higher than 10%. Therefore, salt-tolerant mutants were isolated. The salt-tolerant mutants, HS454 and HS528 which were derived from strain HS3, were both tolerant to salt (2%) and hyper-productive. The growth and L-threonine production by the mutant strain HS454 were almost unaffected by a glucose concentration lower than 10%, but gradually reduced with increasing glucose concentration, up to 15%. However, the mutant strain HS528 showed slightly enhanced growth and L-threonine production with increasing glucose concentration, up to 10-12.5%. Strains HS454 and HS528 produced 69.8 g/l and 74.0 g/l of L-threonine, respectively in a 5-1 jar fermentor.

Culture Media↗

PubMed2000

Salinity induced behavioural changes in malate dehydrogenase and glutamate dehydrogenase activities in rice seedlings of differing salt tolerance.

The activities of malate dehydrogenase in whole tissue extract (NAD(+)-MDH) as well as in mitochondrial (NAD(+)-MDH) and chloroplastic (NADP(+)-MDH) preparations of aminating (NADH-GDH) and deaminating(NAD(+)-GDH) glutamate dehydrogenases were studied in two sets of rice cultivars differing in salt tolerance grown under moderate (7 dS m(-1)) and high (14 dS m(-1)) NaCl salinity levels. A contrasting response to salinity on enzyme activities was found between the sensitive and tolerant cultivars during a 5-20-day growth period of study. NaCl salinity in situ caused increase in all three MDH activities in salt tolerant cvs. CSR-1 and CSR-3 whereas in salt sensitive cvs. Ratna and Jaya 16-100% inhibition in activities was noted. Chloroplastic MDH was extremely sensitive to NaCl. In seedlings of salt tolerant cultivars concomitant increase in both aminating and deaminating GDH activities was observed with increase in salinity level, whereas in sensitive cultivars under higher salinity level decrease in GDH activity was noted. Under in vitro conditions NaCl concentration in the range 1-1000 mM caused gradual inhibition in MDH activity. With 400 mM NaCl in vitro, complete loss of mitochondrial and chloroplastic MDH activities was observed. GDH activity increased with increasing concentration of NaCl up to 200 mM NaCl and other salts in vitro and was inhibited thereafter. However 800 mM NaCl caused complete loss of deaminating GDH activity from sensitive cultivar but not from tolerant cultivar. Results suggest varying behaviour of MDH and GDH in two sets of rice cultivars differing in salt tolerance and that inhibition in the activities of dehydrogenases in salt sensitive rice cultivars due to salinity may be one of the possible reasons for decreased growth of rice plants under saline conditions.

Journal Article↗

PubMed1998

Function and expression of a novel rat salt-tolerant protein: evidence of a role in cellular sodium metabolism.

Higher dietary salt intake in humans is associated with higher BP, but the BP response to NaCl, so-called salt sensitivity, is heterogeneous among individuals. It has been postulated that modifications in cellular cation metabolism may be related to salt sensitivity in mammalian hypertension. The authors have isolated a novel rat complementary DNA, called salt-tolerant protein (STP), that can functionally complement Saccharomyces cervisiae HAL1, which improves salt tolerance by modulating the cation transport system. On high-salt (8% NaCl) diets, both Dahl salt-sensitive and salt-resistant rats displayed an elevated BP and increased STP mRNA expression. Immunohistochemistry using an anti-rat STP antibody demonstrated the presence of STP immunoreactivity in the proximal tubules. In cells that transiently expressed STP, the intracellular [Na+]/[K+] ratio was higher than that in control cells. STP contains predicted coiled-coil and Src homology 3 domains, and shows a partially high degree of nucleotide identity to human thyroid-hormone receptor interacting protein. These results suggest that STP may play an important role in salt sensitivity through cellular sodium metabolism by mediating signal transduction and a hormone-dependent transcription mechanism.

Amino Acid Sequence↗

PubMed1973

Pysiological studies on the recovery of salt tolerance by Staphylococcus aureus after sublethal heating.

Cultures of S. aureus in 100 mM potassium phosphate buffer heated at 52 C for 15 min lost their tolerance to 7.5% NaCl. After incubation in a complex growth medium or in a diluted dialyzed medium in which unheated cells were unable to grow, salt tolerance was regained. Heat injury caused 30% loss of lipid. During recovery, the concentration of C(15) and C(17) fatty acids returned to normal, and there appeared to be an oversynthesis of C(16) and C(18) unsaturated acids. Penicillin abolished the latter reaction without affecting recovery; chloramphenicol did not affect fatty acid oversynthesis but reduced recovery. The K/Na ratio was 12.6 in control cells and 3.4 in injured cells, where it remained during the recovery of salt tolerance. Aspartate uptake was about 10% of the control level after injury and about 35% at recovery. Control cells grew without a lag on subculture, but injured cells which had regained their salt tolerance needed about 2 more h of incubation. Cells recovering with penicillin needed 6 more h, and cells recovering with chloramphenicol did not grow without a prolonged lag. Cells of S. aureus, therefore, may recover their salt tolerance while various membrane functions are still damaged.

Aspartic Acid↗