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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↗
PubMedDate not supplied

Polyamine, carbohydrate, and proline content changes during salt stress exposure of aspen (Populus tremula L.): involvement of oxidation and osmoregulation metabolism.

Excess salt in the soil solution affects the plant either through osmotic or ionic effects. Poplar trees, as fast growing pioneer tree species, are thought to be potential suitable candidates for afforestation on saline soils. Osmotic and oxidative stress induced by salinity could be reduced by the production and accumulation of compatible solutes and osmoprotectants in the plant. In this respect, metabolites of this type could be interesting markers for the improvement of salt stress tolerance in breeding programmes. Results have shown that Populus tremula was able to cope with up to 150 mM NaCl without any effect on plant survival. During stress application, the endogenous level of malondialdehyde did not vary significantly between the treatments, indicating that the level of lipid peroxidation was similar in the control and in the stressed plants. However, proline, spermine, sucrose, mannitol, and raffinose levels increased temporarily or throughout the salt treatment. All these molecules are more or less closely related to antioxidant or osmoprotectant mechanisms during stress, suggesting a key role for these compatible solutes, osmoprotectants, and their metabolism for salt stress resistance. The accumulation of free proline, sucrose and mannitol, and the transitory increase in spermine level observable during low and high NaCl application must be considered as general salt stress reaction markers.

Carbohydrate Metabolism↗
PubMed1986

Variation from plant tissue cultures: biotechnological application to improving salinity tolerance.

Breeding for salt tolerance in crop plants is envisaged as one way to combat a worldwide problem of increasing soil salinity in agricultural land. Tissue culture techniques may prove valuable as a means of achieving this goal. In this review, reports of the selection and characterization of plant cell cultures tolerant to excess salt are assessed, in the context of variability from tissue culture and the significance of cellular physiological adaptation to salinity. The examples of plant regeneration from salt grown cell cultures are also outlined, with emphasis on correlation to the effect of salt on cell cultures, genetic variability for salt tolerance in vitro, and the value of regenerates in the development of salt tolerant plants.

Journal Article↗
PubMed2004

Response of tomato (Lycopersicon esculentum Mill.) to salinity in the early growth stages for agricultural cultivation in saline environments.

Salinity is a serious environmental problem. Growing of plants like tomato can be solution for coping with soil salinity. For this purpose, response of tomato to salinity has been tested in the early growth stages. Characteristics of germination (percentage and period; length and fresh-dry weight of radicle and hypcotyl) and seedling (length and fresh-dry weight of root, shoot and whole plant; leaf number and area based on Relative Growth Rate); Na+ and K+ content of leaf; K+/Na+ rate of leaf has been studied at the 0, 50, 100 and 150 mM NaCl levels. Thus, it determined that tomato can be indicator for agricultural cultivation at the salinity environments at the early growth stages.

Agriculture↗
PubMedDate not supplied

Evaluation of the application of pig slurry to an experimental crop using agronomic and ecotoxicological approaches.

The agronomic and ecotoxicological effects of the application of pig (Sus scrofa) slurry during a maize (Zea mays L.) crop cycle under conditions of forced irrigation were evaluated. The 0.2-ha experimental area, of typical xerofluvent soil and of known vulnerability to nitrate (NO3-) contamination, was divided into 12 plots and provided with water measurement instruments (TDR-probes, vertical tensiometers, and ceramic candles). Samples of soil, water, soil organisms, and the crop were subjected to analytical, agronomic, and biological test procedures. The following fertilizer treatments were applied to triplicate plots: urea (U;170 kg N ha(-1)), and an optimized (P1; 162 kg N ha(-1)) and triple (P3; 486 kg N ha(-1)) dose of pig slurry. Unfertilized plots (P0) served as controls. Calculation was made of seasonal drainage and leached NO3- and sodium losses during the experimental period. Conductivity, heavy metal concentration, hardness, pH, and redox potential were determined in soil solutions. The ecotoxicological evaluation of the soil solution and matrix was based on ecotoxicity bioassays and the quantification of organic and inorganic compounds [phenols, indols, polychlorinated biphenyls (PCBs)]. The results suggest that the P3 treatment is highly contaminating due to the leaching of nitrates and increased soil salinity. Despite the fact that a Folsomia candida reproduction test indicated chronic ecotoxicological effects on the soil in plots treated with P1 and P3, the absence of organic compounds suggests that these effects may be attributable to contaminants not considered in this study.

Animals↗
PubMed2006

[Aboveground biomass of Tamarix on piedmont plain of Tianshan Mountains south slope].

Based on the geo-morphological and hydro-geological characteristics, the piedmont plain of Tianshan Mountains south slope was classified into 4 geo-morphological belts, i.e., flood erosion belt, groundwater spill belt, delta belt, and the joining belt of piedmont plain and Tarim floodplain. A field investigation on the Tamarix shrub in this region showed that there was a significant difference in its aboveground biomass among the four belts, ranged from 1428.53 kg x hm(-2) at groundwater spill belt to 111.18 kg x hm(-2) at the joining belt of piedmont plain and Tarim floodplain. The main reason for such a big difference might be the different density of Tamarix shrub on different belts. Both the Tamarix aboveground biomass and the topsoil's salinity were decreased with increasing groundwater level. Groundwater level was the main factor limiting Tamarix growth, while soil salinity was not.

Biomass↗
PubMed2001

Influence of heavy metals on the accumulation of trimethylglycine, putrescine and spermine in food plants.

Increased contents of cadmium (Cd), lead (Pb), zinc (Zn) and other heavy metals in barley plants enhanced the accumulation of trimethylglycine (betaine), putrescine and spermine. Higher contents of heavy metals in barley were caused by soil enrichment with heavy metals and by soil salinity. The highest accumulation of spermine and betaine (increase 3-fold or 5-fold in comparison to untreated soil substrates) was obtained at the highest concentration of heavy metals in plants. Consequently the betaine-N/protein-N-ratio and the spermine-N/protein-N-quotient increased 3-fold in plants with high heavy metal contents. The biomass formation was not changed significantly by the different experimental treatments.

Betaine↗
PubMed1999

Salt tolerance conferred by overexpression of a vacuolar Na+/H+ antiport in Arabidopsis.

Agricultural productivity is severely affected by soil salinity. One possible mechanism by which plants could survive salt stress is to compartmentalize sodium ions away from the cytosol. Overexpression of a vacuolar Na+/H+ antiport from Arabidopsis thaliana in Arabidopsis plants promotes sustained growth and development in soil watered with up to 200 millimolar sodium chloride. This salinity tolerance was correlated with higher-than-normal levels of AtNHX1 transcripts, protein, and vacuolar Na+/H+ (sodium/proton) antiport activity. These results demonstrate the feasibility of engineering salt tolerance in plants.

Arabidopsis↗
PubMed2000

Leaf gas exchange and solute accumulation in the halophyte Salvadora persica grown at moderate salinity.

The domestication of halophytes has been proposed as a strategy to expand cultivation onto unfavorable land. However, halophytes mainly have been considered for their performance in extremely saline environments, and only a few species have been characterized in terms of their tolerance and physiological responses to moderately high levels of salinity. Salvadora persica is an evergreen perennial halophyte capable of growing under extreme conditions, from very dry environments to highly saline soils. It possesses high potential economic value as a source of oil and medicinal compounds. To quantify its response to salinity, S. persica seedlings were exposed to 200 mM NaCl for 3 weeks, and growth, leaf gas exchange and solute accumulation were measured. The presence of NaCl induced a 100% increase in fresh weight and a 30% increase in dry weight, relative to non-salinized controls. Increases in fresh weight and dry weight were not associated with higher rates of net CO(2) assimilation, however. Analysis of ion accumulation revealed that S. persica leaves accumulated Na(+) as a primary osmoticum. The concentration of Na(+) in leaves of salinized plants was approximately 40-fold greater than that measured in non-salinized controls, and this was associated with significant reductions in leaf K(+) and Ca(2+) concentrations. In addition, a significant accumulation of proline, probably associated with osmotic adjustment and protection of membrane stability, occurred in roots of salinized plants.

Journal Article↗
PubMed1974

Soil ecology of Coccidioides immitis at Amerindian middens in California.

Outbreaks of coccidioidomycosis and isolation of Coccidioides immitis have been reported from Amerindian middens. This study was undertaken to determine the most important ecological component(s) for the occurrence of C. immitis at archeological sites. Soils from 10 former Indian villages with no prior history of coccidioidal infection were collected and cultured. The physicochemical properties of the midden soils were compared with nonmidden soils and positive soils. The following theories for the sporadic distribution of the pathogen in the soil of the Lower Sonoran Life Zone were considered: (i) the Larrea tridentata (creosote bush) association, (ii) the preference for saline soils, (iii) isolation near rodent burrows, and (iv) animals as possible agents of dispersal. Results showed that a high percentage of the midden soils contained C. immitis, whereas none of the adjacent, nonmidden soils yielded the fungus. Physicochemical analyses revealed that the dark color and alkaline pH of the midden soils were due to past organic contamination. Repeated isolations were made from soils with low to moderate alkalinity. Alkalinity and sandy texture were consistent features of all soils in this study. However, the lack of any reports of nonsandy infested soils possibly indicates that the sandy texture and alkalinity may be factors in the distribution of this fungus. The organic content, soil parent material, and color were not important in the soil ecology. L. tridentata was not significant in the macroflora at the infested sites surveyed. Samples collected without reference to rodent burrows yielded a high percentage of recoveries. Animals, although not the major natural reservoir, cannot be ignored as possible factors in the ecology of C. immitis.

Animals↗
PubMed2002

Evaluation of Atriplex lines for selenium accumulation, salt tolerance and suitability for a key agricultural insect pest.

Thirty Atriplex lines were examined for potential habitat improvement and phytoremediation of selenium (Se) contaminated sites. Studies were conducted to determine the biomass production, Se accumulation, and resistance of each line to the beet armyworm, Spodoptera exigua, an agriculturally important insect. Plants were tested using three salinity treatments: (1) control, no Se; (2) NaCl and CaCl2 salts and 1 mg l(-1) Se (12.7 microM) added as sodium selenate; and (3) iso-osmotic to treatment 2 containing high concentrations of sulfate and I mg l(-1) Se added as sodium selenate. Insect bioassays measured survival, growth, and development. Atriplex patula. A. spongiosa 415862, A. hortensis, A. hortensis 379088 and A. hortensis 379092 were among the top biomass producers and Se accumulators, yet they exhibited significantly reduced insect growth, development, and survival. High background sulfate strongly reduced Se accumulation, suggesting that phytoremediation potential is greatest in saline areas having low to moderate sulfate levels. However, these lines grew well in high salinity soils, indicating possible use as a self-seeding cover crop to improve habitat. All plant lines grown in control and high sulfate salinity treatments are acceptable oviposition sites for S. exigua, indicating that these plants would help reduce populations of this key agricultural pest.

Animals↗
PubMed2006

Effect of salinity on root-nodule conductance to the oxygen diffusion in the Cicer arietinum-Mesorhizobium ciceri symbiosis.

Nodule conductance to O2 diffusion has been involved as a major factor of the inhibition of N2 fixation by soil salinity that severely reduces the production of grain legumes. In order to determine the effect of this constraint on the nodule conductance, oxygen uptake by the nodulated roots of Cicer arietinum was measured by recording the concentration of O2 as a function of pO2 in a gas-tight incubator. After germination and inoculation with the strain Mesorhizobium ciceri UPMCa7, the varieties Amdoun 1 and INRAT 93-1 were hydroponically grown in a glasshouse on 1L glass bottles filled with nutrient solution containing 25 mM NaCl. Salinity induced a marked decrease in shoot (30% versus 14%), root (43% versus 20%), and nodule biomass (100% versus 43%) for Amdoun 1 relative to INRAT 93-1. Although salinity completely prevented nodule formation in the sensitive variety Amdoun 1, nodule number and biomass were higher in the first than in the second variety in the absence of salt. This effect was associated with a significantly higher O2 uptake by nodulated root (510 versus 255 micromol O2 plant(-1)h(-1)) and nodule conductance (20 versus 5 microm s(-1)) in Amdoun 1 than in INRAT 93-1. Salinity did not significantly change the nodule conductance and nodule permeability for INRAT 93-1. Thus, the salt tolerance of this variety appears to be associated with stability in nodule conductance and the capacity to form nodules under salt constraint.

Biomass↗
PubMed2003

[Effects of soil factors on arbuscular mycorrhizae (AM) fungi around roots of wild plants].

150 rhizospheric soil samples were collected from 45 wild plants distributed in Shandong Province during 1995-1997. More than forty species of AM fungi were isolated, and the effects of some soil factors on AM fungi were also investigated. It was proved that soil conditions were important factors to the colonization, growth, and distribution of AM fungi. Spore numbers were highest in brown earth, and lowest in alkali-saline soil. Glomus occurred in all types of soil. The occurrence frequency of Gigaspora and Scutellospora was much higher in brown earth. The distribution of AM fungi was also affected by soil pH. Glomus occurred in soil with a wide pH range. The greater of soil alkalinity, the more Glomus were found, while the greater of soil acidity, the more Acaulospora were isolated. Scutellospora occurred mostly in soil with pH of 6.0-7.0, and Gigaspora distributed mainly in acid soil.

Hydrogen-Ion Concentration↗
PubMed2006

Partial substitution of NO(3)(-) by NH(4)(+) fertilization increases ammonium assimilating enzyme activities and reduces the deleterious effects of salinity on the growth of barley.

Productivity of cereal crops is restricted in saline soils but may be improved by nitrogen nutrition. In this study, the effect of ionic nitrogen form on growth, mineral content, protein content and ammonium assimilation enzyme activities of barley (Hordeum vulgare cv. Alexis L.) irrigated with saline water, was determined. Leaf and tiller number as well as plant fresh and dry weights declined under salinity (120 mM NaCl). In non-saline conditions, growth parameters were increased by application of NH(4)(+)/NO(3)(-) (25:75) compared to NO(3)(-) alone. Under saline conditions, application of NH(4)(+)/NO(3)(-) led to a reduction of the detrimental effects of salt on growth. Differences in growth between the two nitrogen regimes were not due to differences in photosynthesis. The NH(4)(+)/NO(3)(-) regime led to an increase in total N in control and saline treatments, but did not cause a large decrease in plant Na(+) content under salinity. Activities of GS (EC 6.3.1.2), GOGAT (EC 1.4.1.14), PEPC (EC 4.1.1.31) and AAT (EC 2.6.1.1) increased with salinity in roots, whereas there was decreased activity of the alternative ammonium assimilation enzyme GDH (EC 1.4.1.2). The most striking effect of nitrogen regime was observed on GDH whose salinity-induced decrease in activity was reduced from 34% with NO(3)(-) alone to only 14% with the mixed regime. The results suggest that the detrimental effects of salinity can be reduced by partial substitution of NO(3)(-) with NH(4)(+) and that this is due to the lower energy cost of N assimilation with NH(4)(+) as opposed to NO(3)(-) nutrition.

Adaptation, Physiological↗
PubMed2004

Chromohalobacter sarecensis sp. nov., a psychrotolerant moderate halophile isolated from the saline Andean region of Bolivia.

A moderately halophilic, aerobic, motile, Gram-negative, rod-shaped bacterium (strain LV4(T)) was isolated from saline soil around the lake Laguna Verde in the Bolivian Andes. The organism is a heterotroph, able to utilize various carbohydrates as a carbon source. It showed tryptophan deaminase, oxidase and catalase activity, but was unable to produce indole or H(2)S; nitrate was not reduced. The G+C content of the genomic DNA was 56.1 mol%. The pH range for growth was 5-10, temperature range was 0-45 degrees C and the range of NaCl concentrations was 0-25 % (w/v). On the basis of 16S rRNA gene sequence analysis, strain LV4(T) was found to be closely related to Chromohalobacter canadensis DSM 6769(T) and Pseudomonas beijerinckii DSM 7218(T); however, its DNA-DNA relatedness with these type strains was low. Strain LV4(T) resembled other Chromohalobacter species with respect to various physiological, biochemical and nutritional characteristics but also exhibited differences. Thus, a novel species, Chromohalobacter sarecensis sp. nov., is proposed, with LV4(T) (=CCUG 47987(T)=ATCC BAA-761(T)) as the type strain.

Amino Acid Oxidoreductases↗
PubMedDate not supplied

Salt stress response and proline accumulation in Brachiaria humidicola plants with and without mycorrhizal inoculation.

The work was carried out to investigate the effects of different concentrations of NaCl on Brachiaria humidicola Rendle in the presence and absence of Glomus etunicatum Becker and Gerdemann, as well as to evaluate some growth parameters and the accumulation of free proline in the plant leaves. The soil used was a Neosoil Fluvic Eutrophic with pH of 6.5, organic matter, 12.8 g kg-1 and soil texture, sandy loam, in which Brachiaria humidicola Rendle cv. 409 was grown. Five NaCl concentrations were tested 0; 0.22; 1.09; 1.96 and 2.84 g. kg-1 of soil, whose electrical conductivity (EC) were 2.22; 4.00; 8.13; 12.53 and 16.50 dS m-1, respectively. Brachiaria humidicola showed salt tolerance when submitted to an EC of 4 dS m-1. There was a reduction of leaf area, dry matter of shoots and roots for the soil treatments beyond EC at 8 dS m-1. Free proline content in the leaves increased together with the increase in soil salinity (EC at 8 dS m-1) demonstrating that plants submitted to EC of 2 and 4 dS m-1 were less affected by salt stress, and consequently accumulated less proline in the leaves. Root colonization was not affected by the increase of NaCl dosage in the soil.

Adaptation, Physiological↗
PubMed1999

Production of canthaxanthin by extremely halophilic bacteria.

Soil samples from a salt farm were used as a source for the isolation of carotenoid-producing bacteria. The conditions for optimum growth and carotenoid production were established for the isolated bacteria. Carotenoids were analysed by spectrophotometry and High Performance Liquid Chromatography (HPLC). Thirty-one red extremely halophilic bacteria were isolated from saline soil samples collected from a salt farm in Alexandria, Egypt. Among the isolated strains, strain TM exhibited the highest carotenoid-producing ability. Maximum growth of strain TM occurred in the presence of high concentrations of sodium chloride and magnesium sulfate. Growth did not occur when NaCl concentration was lower than 10% and the cells lysed at this concentration. Optimum growth of and carotenoid production by strain TM were realized at 37 degrees C in the presence of 1% yeast extract, 0.75% casamino acids, 25% NaCl, 4% MgSO4, 0.2% KCl and at pH 7.2 with shaking for 6 d. Strain TM produced 2.06 mg total carotenoids g(-1) dry cells, including 0.06 mg of beta-carotene and 0.70 mg of canthaxanthin. This is the first report of an extremely halophilic bacterium that produces canthaxanthin.

Journal Article↗
PubMed2004

[Niche characteristics of plants on four environmental gradients in middle reaches of Tarim River].

Tarim River is the longest continental river in China. Along its either bank, the natural vegetation belts are composed of arbors, shrubs and grasses. In this paper, the niche breadths and overlaps of nineteen species on four environmental gradients in the middle reaches of Tarim River were calculated and analyzed. The results showed that the nineteen species could be divided into three groups, based on their average niche breadths. Group one included Populus euphratica, Tamarix ramosissima, T. hispida, Lycium ruthernicum, Alhagi sparsifolia and Phragmites australis, which were constructive species in Tarim River and their niche breadths were greater. Group two included T. leptostachys, Aeluropus pungens, Poacynum hendersonii, Cynanchum sibiricum, Karelinia caspica, Inula salsoloides, Taraxacum sp., and Hexinia polydichotoma, and their niche breadths were smaller than that of group one. Group three included Halimodendron halodendron, Glycyrrhiza inflata, Calamagrostis pseudophragmites, Salsola sp., and Sophora alapecuroides. Based on the niche overlaps matrix, the niche overlaps of the plant species pairs were generally smaller on all the four environmental gradients, because of their probable niche shift or the demand for different environmental resources. Soil moisture and soil salinity were the important environmental factors limiting the plant distribution in the middle reaches of Tarim River.

China↗