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Common bean (Phaseolus vulgaris L.), one of the most important cultivated legumes, requires a high level of water. It is included among the most sensitive species to climate change; drought and salinity cause a reduction in photosynthesis, metabolic and enzymatic alterations, and oxidative stress. To improve crop tolerance to salt, seed priming and acclimation can be useful tools. To test the salt tolerance of beans, a preliminary screening was undertaken on four cultivars of P. vulgaris (Black Turtle, Cargamanto, Bola Roja, Borlotto) by exposing the seeds to different levels of salinity. The salt-sensitive cultivar Borlotto was chosen for experimental greenhouse trials to study the effects of halopriming and acclimation. Primed and non-primed seeds were sown in non-saline soil and acclimated for 2 weeks; then, the plants were watered with non-saline and saline solutions for 4 weeks. At the end of this growth period, the primed plants showed a marked increase in salt stress tolerance, improving the chlorophyll content, phenolic compounds, and many enzymes' activities, in turn reducing the effect of salt on growth and fruit production compared to the non-primed controls. In conclusion, halopriming can be considered a useful tool to enhance salinity tolerance in beans and other salt-sensitive crops. [ABSTRACT FROM AUTHOR]

Soil salinity substantially decreases the productivity in rice (Oryza sativa L.). To elucidate the adaptive responses of salt acclimation, physiological parameters of two rice varieties were evaluated under control and salt stress conditions after acclimation. The results indicated that 50 mM NaCl salinity stress reduced the shoot dry weight in both varieties. However, Vandaran seedlings acclimated with 10 mM NaCl maintained shoot dry weight under 50 mM NaCl salinity stress, whereas acclimation treatment did not enhance the shoot dry weight in Deejiaohualuo. In addition, acclimated Vandaran seedlings maintained better physiological status as determined by enhanced water conservation, improved membrane stability, improved K+ accumulation, lower Na+ concentration, and lower Na+/K+, Na+/Ca2+, Na+/Mg2+ ratios in the leaf tissues compared to non-acclimated seedlings. However, acclimation did not enhance the above-mentioned physiological traits in Deejiaohualuo. Our results suggest that Vandaran possesses better salt acclimation ability as compared to Deejiaohualuo. The present study suggests that the salt acclimation ability of rice relies on the interaction between varieties and their response to acclimation treatment. Na+ exclusion from the shoot may be a key regulation mechanism involved in the salt acclimation process. The acclimation variety would be a better genetic resource to grow in a changing saline environment. [ABSTRACT FROM AUTHOR]

This article describes the growth of 18 acclimatized and 11 non-acclimatized rice varieties grown in a hydroponic nutrient solution in a glasshouse. Four plants from each variety were grown under control conditions, salinity stress following control conditions (salinity), and salinity stress following acclimation (salinity/acclimation) conditions. Sampling was performed at the end of the salinity treatment (36 days of growth). Growth traits such as shoot and root biomass accumulation and lengths were measured for each variety, and the average was calculated using four replicates. This dataset may aid interested researchers in making comparisons with their data and further advance the research on the salinity acclimation process in rice.

Salinity is one of the most important abiotic factors in various natural habitats of microbes. Cyanobacteria are the most widely distributed family of photosynthetic microorganisms in environments with fluctuating salinity. In response to salt stress, many cyanobacteria de novo synthesize compatible solutes to maintain osmotic balance in the cell. However, the regulation of intracellular accumulation of these compounds is still not well understood. The freshwater cyanobacterium Synechococcus elongatus PCC 7942 (Syn7942) exclusively accumulates sucrose as a compatible solute upon salt stress and is thus an ideal model microorganism for studying the metabolism of compatible solute dynamics. Here, we focused on elucidating the regulatory mechanisms involved in salt-induced sucrose accumulation in Syn7942. Using a series of physiological and biochemical experiments, we showed that the ionic effect of salt stress plays an important role in inducing sucrose synthesis, whereby elevated ion concentration directly activates the sucrose-synthesizing enzyme sucrose-phosphate synthase and simultaneously inhibits the sucrose-degrading enzyme invertase, resulting in a rapid sucrose accumulation. Thus, we propose a novel mechanism for cyanobacterial adaption to salt stress and fluctuating salinity, i.e., the ion-induced synergistic modulation of the enzymes synthesizing and degrading compatible solutes. These findings greatly enhance our current understanding of microbial adaptation to salt. [ABSTRACT FROM AUTHOR]

[Display omitted] • Saline microalgae biomass was used to investigate saline anaerobic digestion. • Inoculum used to treat non-saline sewage sludge was acclimated to 14 g·L-1 salinity. • CH 4 production was not impacted by salinity after 10 weeks of semi-continuous test. • Salinity causing 50 % inhibition of CH 4 production was 27 g·L-1 after acclimation. • The population of methylotrophic methanogens increased with salt acclimation. The aim of this study was to acclimate anaerobic prokaryotes to saline microalgae biomass. Semi-continuous experiments were conducted using two 1.5 L mesophilic reactors for 10 weeks, (hydraulic retention time of 21 days). The first reactor was solely fed with sewage sludge (control), while the second received a mixture of sewage sludge and microalgal biomass (80/20 %w/w) cultivated at 70 g·L-1 salinity. The in-reactor salinity reached after the acclimation phase was 14 g·L-1. Biomethane production was comparable between the control and acclimated reactors (205 ± 29 NmL Methane ·g VolatileSolids -1). Salinity tolerance assessment of methanogenic archaea revealed that salinity causing 50% inhibition of methane production increased from 10 to 27 g·L-1 after acclimation. Microbial diversity analyses revealed notable changes in methanogenic archaea populations during co-digestion of saline microalgae biomass, particularly methylotrophic (+27%) and acetotrophic (-26%) methanogens. This study has highlighted the possibility of treating efficiently saline microalgae in co-digestion with sewage sludge in future industrial biogas plants. [ABSTRACT FROM AUTHOR]

Salinity is a serious threat to agriculture productivity. Beneficial microbes could be simple and low-cost biological methods to mitigate the salt toxicity. The present study describes proteome dynamics and salt stress tolerance of the salt-primed (pre-exposed to salt) and directly salt-stressed cyanobacterium Anabaena fertilissima. The difference in the proteome of differently salt-treated and the control cells was the abundance of proteins. Out of 130 proteins resolved in control, 51.8% remained constant, 25.5% were upregulated, and 22.7% protein spots were downregulated in salt-adapted cells (exposed to 500 mM NaCl). However, in cells exposed to 250 mM NaCl, percentage of constant, upregulated, and downregulated proteins was 56.8, 16, and 27.2, whereas in the cells exposed to equimolar NaCl+Na2SO4 mixture, these values were 41.8, 29.4, and 28.7, respectively. This indicated that an altered protein expression occurred in large number of protein species under different salt-stress regimes. Four proteins showing significant and reproducible changes under salt stress showed close homology with photosystem I reaction center subunit XII, epoxyqueuosine reductase, response regulator protein VraR, and molybdopterin biosynthesis protein. The kinetic analysis revealed that salt treatment increased the abundance of all the four identified proteins. Despite the exposure to higher NaCl concentration (500 mM), salt-adapted cells showed minimal hyper accumulation of these four proteins, followed by NaCl and NaCl+Na2SO4 mixture. Lesser accumulation of these identified proteins in salt mixture stressed cells than that of NaCl stressed cells revealed that the availability of sulfur during salt-stress relieved the salt-toxicity, while Cl− increased it. [ABSTRACT FROM AUTHOR]

The present study showed that osmopriming or pretreatment with low HO doses (2 mM) for 6 h alleviated salt-reduced seed germination. The NADPH oxidase activity was the main source, and superoxide dismutase (SOD) activity might be a secondary source of HO generation during osmopriming or HO pretreatment. Hematin pretreatment similar to osmopriming improved salt-reduced seed germination that was coincident with the enhancement of heme oxygenase (HO) activity. The semi-quantitative RT-PCR confirmed that osmopriming or HO pretreatment was able to upregulate heme oxygenase HO-1 transcription, while the application of N, N-dimethyl thiourea (DMTU as trap of endogenous HO) and diphenyleneiodonium (DPI as inhibitor of NADPHox) not only blocked the upregulation of HO but also reversed the osmopriming-induced salt attenuation. The addition of CO-saturated aqueous rescued the inhibitory effect of DMTU and DPI on seed germination and α-amylase activity during osmopriming or HO pretreatment, but HO could not reverse the inhibitory effect of ZnPPIX (as HO inhibitor) or Hb (as CO scavenger) that indicates that the CO acts downstream of HO in priming-driven salt acclimation. The antioxidant enzymes and proline synthesis were upregulated in roots of seedlings grown from primed seeds, and these responses were reversed by adding DMTU, ZnPPIX, and Hb during osmopriming. These findings for the first time suggest that HO signaling and upregulation of heme oxygenase play a crucial role in priming-driven salt tolerance. [ABSTRACT FROM AUTHOR]

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This study was conducted to evaluate the consumer acceptability of post-harvest freshwater prawns marinated in salt solutions (0.5%, 1%, 1.5% and 2% NaCl in the cooked product), and to compare the sensory acceptability of these treatments against prawns that had been salt acclimated pre-harvest while still alive. The salt-acclimated prawns were transferred to 250-L tanks containing 10 ppt solar salt (NaCl with small concentrations of CaCl2 and KCl). Salts were increased by 5 ppt in 2 h increments until 30 ppt was reached. After 18 h of salt acclimation, prawns were chill killed. Prawns that were used for post-mortem marination treatments were transferred to 250 L tanks with freshwater for 18 h prior to harvest and post-mortem marination. Two consumer-based sensory tests were conducted ( n = 102). Results indicate that flavour, texture and overall acceptability of prawns increased ( P < 0.05) as the salt concentration increased from 0.5% to 1.5% in marinated prawns. In addition, marinated prawns that contained 1% sodium chloride after cooking did not differ ( P > 0.05) in acceptability when compared to salt acclimated prawns which contained 0.5% sodium chloride in the cooked product. The salt-acclimated product was preferred ( P < 0.05) over the 0.5% salt marination treatment, although they did not differ in final salt concentration. This indicates that salt acclimation enhanced product acceptability through increased salt concentration as well as due to the salt acclimation process, thus lowering the amount of sodium chloride that was necessary to enhance product acceptability. [ABSTRACT FROM AUTHOR]

In this study, we investigated the cellular and molecular mechanisms that regulate salt acclimation. The main objective was to obtain new insights into the molecular mechanisms that control salt acclimation. Therefore, we carried out a multidisciplinary study using proteomic, transcriptomic, subcellular and physiological techniques., We obtained a Nicotiana tabacum BY-2 cell line acclimated to be grown at 258 mM NaCl as a model for this study. The proteomic and transcriptomic data indicate that the molecular response to stress (chaperones, defence proteins, etc.) is highly induced in these salt-acclimated cells., The subcellular results show that salt induces sodium compartmentalization in the cell vacuoles and seems to be mediated by vesicle trafficking in tobacco salt-acclimated cells. Our results demonstrate that abscisic acid ( ABA) and proline metabolism are crucial in the cellular signalling of salt acclimation, probably regulating reactive oxygen species ( ROS) production in the mitochondria. ROS may act as a retrograde signal, regulating the cell response., The network of endoplasmic reticulum and Golgi apparatus is highly altered in salt-acclimated cells. The molecular and subcellular analysis suggests that the unfolded protein response is induced in salt-acclimated cells. Finally, we propose that this mechanism may mediate cell death in salt-acclimated cells. [ABSTRACT FROM AUTHOR]

Plants can successfully improve their resistance to previously lethal salinity stress by a short exposure to low levels of salt stress, a process known as salt acclimation (SA). In spite of its fundamental significance in theoretical study and agricultural practice, the molecular mechanisms underlying plant SA remain elusive. In this study, we found that salt acclimated Arabidopsis young seedlings can survive subsequent 200 mM NaCl stress. RNA-seq was performed to analyze the genome-wide transcriptional response under SA conditions. Among 518 differentially expressed genes (DEGs) under SA, 366 up-regulated genes were enriched for cell wall biosynthesis, osmoregulation, oxidative stress, or transcription factors. Seven DEGs participate in the synthesis of lignin and 24 DEGs encode plant cell wall proteins, suggesting the importance of cell wall remodeling under SA. Furthermore, in comparison to non-acclimated salt stress, 228 of 245 DEGs were repressed by acclimated salt stress, including many genes related to ethylene biosynthesis and signaling pathway. In addition, MAPK6, a major component of the ethylene signaling pathway, was found to play a crucial role in SA. Our transcriptomic analysis has provided important insight on the roles of transcription factors, cell wall remodeling, and the ethylene biosynthesis and signaling pathways during SA in Arabidopsis. [ABSTRACT FROM AUTHOR]

Synechocystis sp. PCC 6803 is the most popular cyanobacterial model for prokaryotic photosynthesis and for metabolic engineering to produce biofuels. Genomic and transcriptomic comparisons between closely related bacteria are powerful approaches to infer insights into their metabolic potentials and regulatory networks. To enable a comparative approach, we generated the draft genome sequence of Synechocystis sp. PCC 6714, a closely related strain of 6803 (16S rDNA identity 99.4%) that also is amenable to genetic manipulation. Both strains share 2838 protein-coding genes, leaving 845 unique genes in Synechocystis sp. PCC 6803 and 895 genes in Synechocystis sp. PCC 6714. The genetic differences include a prophage in the genome of strain 6714, a different composition of the pool of transposable elements, and a ∼40 kb genomic island encoding several glycosyltransferases and transport proteins. We verified several physiological differences that were predicted on the basis of the respective genome sequence. Strain 6714 exhibited a lower tolerance to Zn2+ ions, associated with the lack of a corresponding export system and a lowered potential of salt acclimation due to the absence of a transport system for the re-uptake of the compatible solute glucosylglycerol. These new data will support the detailed comparative analyses of this important cyanobacterial group than has been possible thus far. Genome information for Synechocystis sp. PCC 6714 has been deposited in Genbank (accession no AMZV01000000). [ABSTRACT FROM PUBLISHER]

Abstract: Post harvest acclimation of live freshwater prawns to a mixture of water and marine salt increases the consumer acceptability of the finished product. However, the high cost of marine salts prohibits their use in commercial practice. Therefore, the identification of successful, cost effective salt alternatives to replace acclimation with marine salt could potentially lead to an economically practical method to add value to prawns. This study was conducted to evaluate the consumer acceptability of freshwater prawns that were harvested and either held and acclimated with different salt treatments or marinated with salt. Post-harvest freshwater prawns were transferred to 250-l tanks containing one of five salt treatments (10ppt): Instant Ocean (IO; marine salt), solar salt (SS-NaCl), solar salt supplemented with KCl and CaCl2 (SS+), fresh water (FW), and fresh water marinated postmortem (marinated). Salts were increased by increments of 5ppt every 2h until 30ppt was achieved. Prawns were harvested after 18h of salt acclimation. Survival was recorded and prawns were then chill killed, de-headed and frozen. Freshwater control samples were divided into non-marinated controls and samples that were marinated in 5% NaCl for 18h at 2–3°C with either shells on or off prior to freezing. Three consumer panels (n =60) were conducted to assess the acceptability of prawns on a 9-point hedonic scale. Survival was 67% in the SS treatment with the highest survival in the FW (95%) followed by IO (85%) and SS+ (73%). Consumer acceptability studies indicated that prawns marinated post-mortem without the shell were more acceptable (P <0.05) than those from other treatments with respect to flavor, texture and overall acceptability. In addition, prawns marinated in the shell and from all salt acclimation treatments were preferred (P <0.05) over the freshwater prawns. Panelists were clustered into 5 consumer groups of which 94.2% of consumers rated the post-mortem marinated prawns without the shell as like slightly or greater. These data suggest that post-mortem marination or salt acclimation significantly improves the acceptability of the freshwater prawns. Live acclimation to salt enhances flavor due to significantly higher concentrations of glutamic acid in the tail muscle of prawns in comparison to that found in prawns from the FW and marinated treatments. [Copyright &y& Elsevier]

Freshwater prawns, Macrobrachium rosenbergii, were harvested and transferred to holding tanks containing aerated well water. One group of prawns was held in the well water without any addition of salt (control). For post-harvest salt acclimation, experimental treatments consisted of different salt sources (solar, halite, marine) that were initially added to achieve a salinity of 10 ppt. Then, 5-ppt increases occurred every two hours until the salinity was 30 ppt, with 10-h exposure at this salinity prior to harvesting. A randomized complete block design with three replications was used to evaluate the effect of salt type on the sensory acceptability (n = 60 consumers per replication) of prawns. All treatments had mean acceptability scores between like slightly and moderately; inclusion of solar, marine, and halite salts all enhanced (p < 0.05) flavor, texture, and overall acceptability. In addition, the clusters with the greatest numbers of consumers (n > 100) liked all treatments but preferred (p < 0.05) prawns from the solar or halite salt treatments over those from the control treatment. The addition of solar or halite salt enhanced the sensory acceptability of prawns, but further testing is needed to optimize acclimation conditions as comparatively high mortality occurred in two acclimation treatments. [ABSTRACT FROM AUTHOR]

The effect of road salt on the eating of bacteria or bacterivory by the ciliate, Tetrahymena thermophila, was followed in non-nutrient Osterhout's solution with Escherichia coli expressing green fluorescent protein. Bacterivory was impaired at between 0.025 and 0.050% w/v but the ciliates appeared to have normal morphologies and motilities, whereas at above 0.1%, bacterivory was blocked and many ciliates died. By contrast, E. coli remained viable, suggesting salt could alter predator–prey relationships in microbial communities. In nutrient medium, salt was not toxic and the ciliates grew. After growth in salt, ciliates consumed bacteria in 0.2% salt, indicating the salt acclimation of bacterivory. Bacteria and ciliates were added to urban creek samples to compare their capacity to support exogenous bacterivory. Even though samples were collected weekly for a year and be expected to have fluctuating salt levels as a result of deicing, all creek samples supported a similar level of bacterivory. [Copyright &y& Elsevier]

Tolerance of salt stress in potato ( Solanum tuberosum L.) increased when the plants were pre-exposed to low concentrations of salt (salt acclimation). This acclimation was accompanied by increased levels of abscisic acid (ABA) in the shoot. To further study the role of roots and shoots in this acclimation process, reciprocal grafts were made between a salt-tolerant (9506) and salt-sensitive ABA(−) mutant and its ABA(+) normal sibling potato genotype. The grafted plants were acclimated with 75 or 100 mM NaCl for 3 weeks and then exposed to 150–180 mM NaCl, depending on the salt tolerance of the rootstock. After 2 weeks of exposure to the salt stress, the acclimated and unacclimated plants were compared for physiologic and morphologic parameters. The response to the salt stress was strongly influenced by the rootstock. The salt-tolerant 9506 rootstock increased the salt tolerance of scions of both the ABA-deficient mutant and its ABA(+) sibling. This salt tolerance induced by the rootstock was primarily modulated by salt acclimation and manifested in the scion via increased plant water content, stem diameter, dry matter accumulation, stomatal conductivity, and osmotic potential, and is associated with a reduction in leaf necrosis. There was also a pronounced scion effect on the rootstock. Using 9506 as a scion significantly increased root fresh and dry weights, stem diameter, and root water content of ABA(−) mutant rootstocks. Specific evidence was found of the role of exogenous ABA in the enhancement of water status in grafted plants under salt stress beyond that of grafting alone. This was verified by more positive stomatal conductivity and upward water flow in ABA-treated grafted and nongrafted plants and the absence of upward water flow in nontreated grafted plants through NMR imaging. Grafting using either salt-tolerant scions or rootstocks with inherently high ABA levels may positively modify subsequent responses of the plant under salt stress. [ABSTRACT FROM AUTHOR]

Summary: Two sets of experiments to determine the effect of mycorrhiza on soybean (Glycine max) growth under saline conditions and to investigate the salt acclimation of mycorrhizal fungi were conducted. In the first experiment, the effect of an arbuscular mycorrhizal (AM) fungus Glomus etunicatum on mineral nutrient, proline and carbohydrate concentrations and growth of soybean. Under different NaCl concentrations (0, 50, 100, 150 and 200mM) was evaluated. Salinity decreased AM colonization. In both the M and nonAM plants shoot and root proline and shoot Na and Zn concentrations were increased under salinity. Soybean plants inoculated with the AM fungus had significantly higher fresh and dry weight, root proline, P, K and Zn but lower shoot proline and Na concentrations compared to the non inoculated plants. In the second experiment, the AM fungus was pre-treated with NaCl (salt acclimation) then was used as inoculum for soybean plants subjected to 100mM NaCl. Root colonization, fresh and dry weight, root proline, P, K and Zn concentrations were greater in soybean plants inoculated with the salt pre-treated fungus, compared to those inoculated with the nonsalt pre-treated fungus. However, for Na, the situation was the opposite. Based on these results, the AM inoculation helps the growth of soybean plants grown in saline conditions. When the AM fungus was pre-treated with NaCl with a gradual increase of concentration, and then exposed to a sudden salt stress, their efficiency was increased. This may be due to the acclimation of the AM fungus to salinity. [Copyright &y& Elsevier]

The intestinal caeca reabsorb urinary sodium chloride (NaCl) and water (Rice and Skadhauge 1982). Free water may be generated if the reabsorbed NaCl is secreted via salt gland secretion (Schmidt-Nielsen et al. 1958). Therefore ceacal ligation should (a) reduce hingut NaCl and water reabsorption, (b) enhance the increase in plasma osmolality during saline acclimation, and (c) affect drakes more than ducks. Twelve Pekin drakes and 13 Pekin ducks, Anas platyrhynchos, were caecally ligated or sham operated before acclimation to 450 mmol · 1 NaCl. Body mass, hematocrit, plasma osmolality, and inonic concentrations of plasma, cloacal fluid, and salt gland secretion were measured after each increase in drinking water salinity. Osmoregulatory organ masses were determined. Caecal ligation did not effect plasma osmolality or ion concentrations of plasma, cloacal fluid, or salt gland secretion, but reduced salt gland size in ducks. Drakes and ducks drinking fresh water had the same hematocrit, plasma osmolality, and plasma concentrations of Na and Cl. In both sexes exposure to 75 mmol · 1 NaCl significantly decreased plasma [Na] and doubled cloacal fluid [Na]. Exposure to 450 mmol · 1 NaCl decreased body mass and increased hematocrit, plasma [Na], [Cl], and plasma osmolality (more in drakes than in ducks); cloacal fluid osmolality nearly doubled compared to freshwater-adapted ducks, due mainly to osmolytes other than Na and Cl. The [Cl] in salt gland secretion only slightly exceeded drinking water [Cl]. [ABSTRACT FROM AUTHOR]

The effect of aldosterone (1 μmol/l for 4-6 h) on Na transport across toad skin ( Bufo viridis) was studied in skins preincubated in vitro. Short-circuit current ( I) was consistently and reproducibly elevated in skins from NaCl(100 and 200 mmol/l)-acclimated toads, where the baseline I was greatly reduced. The effect of aldosterone was tested in NaCl and NaNO Ringer's and also after oxytocin (50 mU/ml) in the latter conditions. Apical membrane conductance of the principal cells increased consistently after aldosterone in all skins and was linearly correlated with the I under all conditions. This confirms that the stimulation of Na transport originates from the effect of the aldosterone on apical Na channels. Basolateral membrane conductance was also significantly elevated compared with control pieces in those tissues that were preincubated with aldosterone for 4-6 h. The increase, however, did not correlate with the magnitude of the I. It is therefore concluded that aldosterone specifically stimulates, in addition to the apical effect, the basolateral membrane conductance. This stimulation appears to be direct and not a secondary response to the elevation of transepithelial transport rate. [ABSTRACT FROM AUTHOR]

A water channel, the frog aquaporin-CHIP (FA-CHIP) was recently cloned from Rana esculenta urinary bladder. The 28.9 kDa encoded protein shows 78.8%, 77.4%, 42.4% and 35.6% identity with rat CHIP28, human CHIP28, rat WCH-CD and gamma-TIP, other members of the new transmembrane water channel family (Aquaporin-CHIP). We have now studied membranes from different frog (R. esculenta) organs employing semiquantitative PCR using FA-CHIP specific primers and an internal standard to quantify the PCR products. The FA-CHIP mRNA was abundantly expressed in the frog urinary bladder, skin, lung and gall bladder, while a lower expression was detected in the colon, liver and oviduct. FA-CHIP mRNA was not detected in the frog kidney, erythrocytes and brain but its expression was observed in the toad (Bufo arenarum) urinary bladder and skin, showing that FA-CHIP is probably a general amphibian water channel. Salt acclimation is known to increase the water permeability of frog and toad epithelia. We have now observed that salt acclimation for 1, 3, 4 or 5 days markedly increased skin and urinary bladder FA-CHIP mRNA expression. It is generally accepted that water permeability is controlled in these tissues by the rate of water channel transfer from subapical vesicles (aggrephores) to the apical membrane. Our results indicate that water permeability is also regulated at the level of the FA-CHIP transcription. [ABSTRACT FROM AUTHOR]

• Rice varieties differ in their ability to acclimate to salinity stress. • Acclimatized rice varieties exhibited 'Na+ excluder' and 'Na+ accumulator' characteristics in leaf Na+ homeostasis. • Acclimation treatment increased expression of the OsHKT1;5 or OsNHX1 gene in acclimatized varieties. • Rice develops different mechanisms of salt acclimation using two Na+ transport systems. To elucidate the mechanisms of salt acclimation, physiological parameters of 70 rice varieties were compared under control and salt stress conditions after the acclimation treatment. The results indicated that some rice varieties had the ability to acclimatize to salt stress, exhibiting improved growth following the acclimation treatment under subsequent salinity stress compared to those without acclimation treatment. Conversely, some varieties exhibited reduced growth both with and without acclimation treatment under subsequent salinity stress. Acclimatized varieties had differential patterns of Na+ accumulation in the leaf blades because some varieties reduced Na+ accumulation under salinity stress, whereas others did not. Under salt stress, the acclimatized varieties with low Na+ accumulation in the leaf blades highly induced the expression of the OsHKT1;5 gene in the roots, which may contribute to Na+ exclusion from the shoots. On the other hand, the acclimatized varieties with high Na+ accumulation in the leaf blades exhibited higher induction of the OsNHX1 gene, whose gene product participates in the compartmentalization of Na+ into vacuoles. Thus, rice develops different mechanisms of salinity acclimation using two Na+ transport systems, and active regulation of Na+ transport at the transcription level may be involved in the salt acclimation process and enhance salinity tolerance. [ABSTRACT FROM AUTHOR]

High salinity and low temperature are generally considered to have negative effects on the formation, stability and performance of aerobic granular sludge (AGS). This study investigated whether and how salinity acclimation strategies can enhance aerobic granulation at low temperature (12 °C) in three sequencing batch reactors (SBRs). Stepwise increased concentrations of NaCl (2–10 and 4–20 g/L) were added to the influent of R1 and R2 with steps of 1 and 2 g/L per week respectively, while R0 was set as a control (salt-free). The granulation processes in R1 and R2 were rapidly started up within 9 days, and were completed within 21 and 18 days, respectively. By contrast, R0 took 25 days and 49 days to start and complete granulation. The salinity acclimation strategies improved sludge hydrophobicity, reduced repulsion barrier between cells, and stimulated EPS production during granulation processes, which simultaneously promoted the formation of AGS. When the influent salinity reached 14 g/L on day 35, granule hydrophobicity, density and size in R2 sharply decreased and granules began to disintegrate afterwards. When operated under salt-free condition, sludge bulking occurred in R0 since day 60. The treatment performance was thus impaired in these two reactors, especially in R2 with significant biomass loss. Conversely, the AGS developed in R1 maintained stable structure with high biomass concentration (8.0 gSS/L) and excellent treatment performance for COD (90%), ammonium (95%) and total nitrogen (70%). Genera Thauera , Azoarcus , and Nitrosomonas were more enriched, while Flavobacterium and Meganema were more suppressed in R1, which would have contributed to granule stability and treatment performance. In conclusion, great care has to be taken for cultivating and operating AGS at low temperature for treating saline wastewater. Increasing salinity with a lower salt gradient provides a possibility for rapid granulation of AGS with excellent treatment performance under such conditions. Unlabelled Image • Aerobic granulation for saline wastewater treatment at 12 °C was investigated. • Fast formation of AGS was observed with gradual salinity acclimation strategies. • AGS is sensitive to salinity increase at 12 °C with a threshold of 14 g NaCl/L. • Increasing salinity with a smaller step is preferred for AGS at low temperature. [ABSTRACT FROM AUTHOR]

An analysis of the salinity tolerance of 354 Arabidopsis thaliana accessions showed that some accessions were more tolerant to salt shock than the reference accession, Col-0, when transferred from 0 to 225 mM NaCl. In addition, several accessions, including Zu-0, showed marked acquired salt tolerance after exposure to moderate salt stress. It is likely therefore that Arabidopsis plants have at least two types of tolerance, salt shock tolerance and acquired salt tolerance. To evaluate a role of well-known salt shock tolerant gene SOS1 in acquired salt tolerance, we isolated a sos1 mutant from ion-beam-mutagenized Zu-0 seedlings. The mutant showed severe growth inhibition under salt shock stress owing to a single base deletion in the SOS1 gene and was even more salt sensitive than Col-0. Nevertheless, it was able to survive after acclimation on 100 mM NaCl for 7 d followed by 750 mM sorbitol for 20 d, whereas Col-0 became chlorotic under the same conditions. We propose that genes for salt acclimation ability are different from genes for salt shock tolerance and play an important role in the acquisition of salt or osmotic tolerance.