Search

Salicornia brachiata is an extreme halophyte that commonly grows on marsh conditions and is also considered a promising resource for drought and salt-responsive genes. To unveil a glimpse of stress endurance by plants, it is of the utmost importance to develop an understanding of stress tolerance mechanisms. ‘Early Responsive to Dehydration’ (ERD) genes are defined as a group of genes involved in stress tolerance and the development of plants. To increase this understanding, parallel to this expedited thought, a novel SbERD4 gene was cloned from S. brachiata, characterized, and functionally validated in the model plant tobacco. The study showed that SbERD4 is a plasma-membrane bound protein, and its overexpression in tobacco plants improved salinity and osmotic stress tolerance. Transgenic plants showed high relative water, chlorophylls, sugars, starch, polyphenols, proline, free amino acids, and low electrolyte leakage and H2O2 content compared to control plants (wild type and vector control) under different abiotic stress conditions. Furthermore, the transcript expression of antioxidant enzyme encoding genes NtCAT, NtSOD, NtGR, and NtAPX showed higher expression in transgenic compared to wild-type and vector controls under varying stress conditions. Overall, the overexpression of a novel early responsive to dehydration stress protein 4-encoding gene (SbERD4) enhanced the tolerance of the plant against multiple abiotic stresses. In conclusion, the overexpression of the SbERD4 gene mitigates plant physiology by enduring stress tolerance and might be considered as a promising key gene for engineering salinity and drought stress tolerance in crops.

BACKGROUND Ice plant is a halophyte, known for its antioxidant activity and for being a highly functional food. It is capable of increasing its contents of health-promoting compounds when subjected to certain stresses such as salinity. The objective of this work was to determine the plant's best growing conditions to achieve both an optimal production of bioactive metabolites and high crop yield. Mesembryanthemum crystallinum were grown under semi-controlled conditions and four saline treatments were applied at: 0, 100, 200 and 300 mmol L-1 sodium chloride (NaCl), respectively. RESULTS The 100 mmol L-1 NaCl treatment induced a slight increase in shoot dry weight (DW) and enhanced the leaf area. At higher salinity levels, however, the shoot biomass decreased. The concentration of starch and total proteins declined as the concentration of salt increased, while the total soluble sugars (TSS) content was lower in 100 and 300 mmol L-1 NaCl treatments. Proline increased in conditions over 100 mmol L-1 NaCl. Furthermore, plants grown with 300 mmol L-1 of NaCl presented the highest values of glutathione, ascorbic acid and vitamin C. Antioxidant enzymes activity and total phenolics increased with the severity of the salinity. CONCLUSION Ice plant accumulates high levels of health-promoting compounds when grown with 300 mmol L-1 NaCl. A high concentration of beneficial compounds, however, is detrimental to the plant's growth. Moreover, 100 mmol L-1 NaCl treatment not only improved the concentration of bioactive and antioxidant compounds but also preserved the crop yield. It could thus be interesting to promote the cultivation of this high nutritional value plant in environments of moderate salinity. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Vermicompost is a commonly used organic fertilizer that can effectively improve the fertility and structure of saline soil. However, the effect of vermicompost on the growth of halophytes in coastal saline soil, especially under flooding conditions, is obscure. We conducted two greenhouse experiments in which seeds and seedlings, respectively, of the Suaeda salsa were subjected to no flooding, episodic flooding, or continuous flooding, crossed with or without vermicompost addition, in a factorial design. Continuous flooding decreased seed germination and seedling biomass of S. salsa. Under no flooding or episodic flooding, vermicompost addition significantly increased seed germination and seedling growth in S. salsa, but vermicompost addition had no significant effects under continuous flooding. Vermicompost addition increased the stability of soil aggregates and decreased soil electrical conductivity, thereby improving the soil quality. Our results suggest that vermicompost addition could be an effective strategy for enhancing the population growth of S. salsa in saline soil and benefit the restoration of the S. salsa community in the Yellow River Delta, China.

Salinity is a major problem affecting crop production all over the world. A wide range of adaptation strategies are required to overcome this problem. Endophytic bacteria can build a symbiotic association with their host to improve host plant salt tolerance. In this study, eighteen bacterial endophyte strains were isolated from two native halophytic plants Arthrocnemum macrostachyum and Spergularia marina, and identified as Bacillus, Brevibacillus, Agrobacterium, and Paenibacillus. These endophytic strains exhibit plant growth-promoting activities including phosphate solubilizing, ammonia production, biocontrol of phytopathogen, extracellular enzymatic activities, and indole-3-acetic acid production under normal and salinity stress. A pot experiment was conducted under field conditions to alleviate the harmful effects of soil salinity on bean (Vicia faba L.) by inoculating their seeds with the most potent bacterial isolates Bacillus subtilis (AR5) and Bacillus thuringiensis (BR1). Salinity treatments induced a significant decrease in both growth parameters and metabolic activities, while the activity of antioxidant enzymes and proline content was significantly increased. However, salinity stress induced higher contents of Na+ and decreased contents of N+, P3+, K+, Ca2+, Mg2+, and K+:Na+, it was found that treatment with B. subtilis (AR5) and B. thuringiensis (BR1) individually or in a combination mitigated the effect of salt stress and improved the plant height, shoot dry weights, proline contents, enzymes activities as well enhanced the accumulation of mineral nutrients in shoot plants. Our results concluded that treatment with co-inoculation of B. subtilis (AR5) and B. thuringiensis (BR1) exerted the greatest effect in alleviating the harmful effect of soil salinity stress and can be used as a suitable bio-approach to reclaim salinity-stressed soils.

Prosopis strombulifera (Lam.) Benth. is a halophytic shrub abundant in high-salinity areas in central Argentina, with high tolerance against NaCl but strong growth inhibition by Na2SO4. In the present study, the modulation of the antioxidant systems (enzymatic and non-enzymatic components) was analyzed under different salt treatments (NaCl, Na2SO4 and the iso-osmotic mixture) in hydroponic cultivation. Na2SO4-treated plants showed strong indications of oxidative stress (H2O2 and O2-• increase). Modifications in antioxidant enzymes activities were observed mainly under Na2SO4 treatment, where CAT seems to play an important role in early detoxification of H2O2 in roots, whereas SOD and APX have a predominant role in leaves. As part of the non-enzymatic system, 21 compounds were identified in leaves, being polyphenols the most abundant. Control plants contained the major variety of detected phytochemicals (14). Na2SO4-treated plants contained 10 compounds and NaCl-treated plants nine compounds, but with a different profile. NaCl-treated plants showed the highest antioxidant capacity. Our findings confirm that different types of salt treatments provoke a differential modulation of the antioxidant systems. Polyphenols and other ROS-detoxifying compounds, in a joint action with the enzymatic antioxidant system, are proposed to have a fundamental role in the cellular protection of P. strombulifera plants under severe oxidative stress. Our findings also highlight the potential of this halophyte as a valuable source of bioactive compounds with high antioxidant activity and health benefits.

Salinity is one of the major causes of abiotic stress that leads to a reduction in crop yield. One strategy to alleviate and improve crop yield is to use halophytes. These types of plants naturally produce bioactive secondary metabolites, proteins, carbohydrates, and biopolymers that are involved in specialized physiological adaptation mechanisms to alleviate soil salinity. These traits could be leveraged and, in turn, be the focus of future breeding programs aimed to improve salinity resistance in traditional crops. Recently, the field of nanotechnology has gained the attention of researchers involved in agricultural science and associated disciplines. However, information on salinity tolerance mechanisms of halophytes, based on nanoparticles in agricultural crop plants, is limited. Recently, the use of selected halophytic-based nanoparticles has shown to improve crop performance by enhancing the plants' ion flux, improving water efficiency, root hydraulic movement in the favor of plant photosynthesis, the production of proteins involved in oxidation-reduction reactions, reactive oxygen species (ROS) detoxification, and hormonal signaling pathways under stress. Therefore, the aim of this review is to highlight the application of halophytic nanoparticles in alleviating salt stress in plants by understanding the mechanisms of plant growth, water relation, ion flux, photosynthesis, and the antioxidant defense system. This review also addresses uncertainties, ecotoxicological concerns, and associated drawbacks of nanoparticles on the environment. Future research perspectives with respect to the sustainable usage of nanoparticles in saline agriculture have also been presented.

Introduction: Drought is undoubtedly one of the most important environmental stresses limiting the productivity of crop plants around the world. An optimal partitioning of dry matter between root and shoot, therefore is of crucial importance for crop yield under drought stress. Deficit irrigation strategy and planting crops with low water requirements and low expectations, for example, Kochia is very important under drought stress. Kochia is a salt- and drought-tolerant species that can be grown on drought soils, yielding fodder in quantities approaching that produced by alfalfa. The aim of this greenhouse study was investigating root and shoot growth of Kochia under drought stress conditions.Materials and Methods: To study the effects of drought stress on root and shoot growth of kochia, a pot experiment was carried out as completely randomized design with three replications in University of Ferdowsi in 2013. There were 9 treatments included control (no stress) (NS-NS=100% field capacity (FC)), moderate drought stress (70% FC) during the vegetative phase (MS-NS), severe drought stress (30% FC) during the vegetative phase (SS-NS), moderate drought stress during the reproductive phase (NS-MS), severe drought stress during the reproductive phase (NS-SS), moderate drought stress during the vegetative phase and severe drought stress during the reproductive phase (MS-SS), severe drought stress during the vegetative phase and moderate drought stress during the reproductive phase (SS-MS), moderate drought stress during total growth period (MS-MS) and severe drought stress during total growth period (SS-SS). At the beginning of anthesis, plant height and branch number were recorded. Then plants were harvested and leaves, stems, and roots were separated. The fresh weight of the organs was recorded. Root volume was measured. Leaf area measured using a leaf area meter (LI-COR model) and root area was measured by Atkinson method. Then, leaves, stems, and roots dried in an oven at 75°C for 48 hours until mass reached and dry weight was recorded. For statistical analysis, analysis of variance (ANOVA) and LSD test were performed using SAS ver. 9.1 software.Results and Discussion: Results showed that the highest and lowest plant height, leaf area, leaf, stem and total fresh and dry weight observed in control and severe drought stress during growth period, respectively. Significance of traits related to plant aerial parts due to morphological changes of root plants, which is actually a plant response to drought stress. Also, effect of drought stress was significant on root length, area and volume, fresh and dry weight, root length ratio to plant height. The highest and lowest of these traits were observed in control and severe drought stress during growth period, respectively. Drought stress thereby mostly reduced plant height and increased at least root length, leading to higher root/shoot ratio. Most importantly, the length of root was greater in the moderate drought-treated plants than the control plants at the end of the drought and recovery periods. Number of lateral branches and root dry weight/shoot dry weight ratio did not differ significantly with control. Generally, root and shoot growth under drought stress conditions is reduced that the amount of reduction depends on the growth stage of the plant, intensity and duration of the stress.Conclusions: Finally, this study showed that the maximum amount of Kochia forage was obtained when the water is 100% FC to increase the number and size of the cells and, consequently, increase the yield. However, Kochia forage decreased 19% by decreasing 30% of irrigation water in treatments of moderate stress during total growth period in compared to the control plants. In addition to saving water, more land can be cultivated.

Information about responses of plants grown from heteromorphic seeds is limited and inconclusive. This is especially true of subtropical halophytes where such studies have yet to be published. Therefore, growth, water-relations, and oxidative stress mitigation of plants germinated from the heteromorphic seeds of the succulent halophyte Arthrocnemum indicum under increasing (0, 300, and 900 mM NaCl) salinity were studied. Growth of plants from only small seeds was stimulated in moderate (300 mM NaCl) salinity. High (900 mM NaCl) salinity inhibited the growth of plants emerged from both small and large sized seeds. Plants germinating from both seed sizes demonstrated similar patterns of osmotic adjustment and did not develop signs of oxidative damage under increasing salinity. However, the magnitude of hydrogen peroxide and antioxidant responses differed between plant types. Under moderate salinity, plants from small seeds showed constitutive activities of most antioxidant enzymes (except superoxide dismutase) and levels of non-enzymatic antioxidants (except ascorbate). Conversely, a decline in activities of most antioxidant enzymes and levels of most non-enzymatic antioxidants occurred in plants from large seeds. While under high salinity, increased ascorbate peroxidase, glutathione, and polyphenol levels, along with unaffected ascorbate and superoxide dismutase levels, occurred in plants from small seeds. In plants from large seeds, there were increased ascorbate and polyphenol levels, but changes to the ascorbate peroxidase levels were not observed. These results thus indicate differential growth and hydrogen peroxide homeostasis in A. indicum plants emerged from heteromorphic seeds.

Nitrate plays both nutritional and osmotic roles in the salt tolerance of halophytes. However, how halophytes take up NO3− under saline conditions is still not well understood. Seedlings of Suaeda salsa L. were treated with 0, 200 and 500 mM NaCl under 0.5 mM NO3−-N with or without Na3VO4 (the inhibitor of plasma membrane H+-ATPase) for 24 h. Salinity treatment of 200 mM NaCl up-regulated the gene expression of nitrate transporter 2.1 (SsNRT2.1) in the roots, increased the root net influx of H+ and NO3− and 15NO3− accumulation in the leaves and roots. The expression of SsNRT2.1 at 200 mM NaCl with Na3VO4 was much higher than that without supplying Na3VO4, and the opposite trend was found in 15NO3− accumulation in the leaves and roots. Supplying Na3VO4 had no significant effect on the net H+ flux, but induced a net NO3− efflux in the roots at 200 mM NaCl. Salinity may directly activate the expression of SsNRT2.1 and promote NO3− uptake via the increment of pumping H+ by PM H+-ATPase in S. salsa, which may explain why certain halophytes can absorb and accumulate high concentration of NO3− under low NO3− and high salinity conditions.

In some areas of the world, high levels of sodium sulfate (Na2SO4) are found in the soil together with sodium chloride (NaCl). However, most studies on salinity are performed utilizing only NaCl as a salinizing agent. Generally, plant species have different tolerance/susceptibility responses when grown in the presence of these salts. Some studies showed that Na2SO4 seems to be more inhibitory than NaCl for the growth of species such as barley, wheat, sugar cane, beet, tomato, wild potato, and others. However, studies focusing on how Na2SO4 can affect the biochemical and physiological processes of plants are very scarce. This review provides an overview on the effects of Na2SO4 on different crops and plants species with a special emphasis on the tolerance/non-tolerance mechanisms of the halophyte Prosopis strombulifera under elevated NaCl and Na2SO4. A better understanding of the tolerance mechanisms in this particular species will help to identify cultivars of crop species that are more tolerant to Na2SO4. This knowledge could be used to extent cultivation of certain crop plants on Na2SO4 containing soils.

The capacities of the euhalophyte SaLi-Cornia perennans Willd. and glycohalophyte Artemisia santonica L. to accumulate NaCl, Cu, and Cd, as well as their physiological and biochemical responses to these compounds, was investigated. Seeds were germinated in distilled water for 1–3 days and then sown in containers with sand. Plants were watered with Robinson’s nutrient solution. After 3 months, plants were divided into two groups: experimental and control. In the experimental group, soil was treated with 1M NaCl, 10 mM Cu(NO3)2, and 10 mM Cd(NO3)2 for 24 h. The exposure to high concentration of NaCl in the experiment did not affect the baseline level of Na, which was twice as high in S. perennans as in A. santonica. Plant exposure to Cu and Cd caused their accumulation in the aboveground parts of both species. The accumulation capacity of the euhalophyte was many times higher than that of the glycohalophyte. We analysed functional parameters of leaves by measuring photosynthetic pigments, structural parameters of membranes by assessing the lipid profile, and the balance of pro/antioxidant processes. Using data on changes in several biochemical parameters, the sensitivity of the two different halophytes to metal ions was as follows: for S. perennans – Cu > Na > Cd; for A. santonica – Na > Cu > Cd. Our findings suggest that S. perennans can be used for heavy metal extraction from soil in phytoremediation, whereas A. santonica will be more effective for greening of polluted territories.

Understanding the effect of soil salinity on the diversity and species distribution of plant communities in inland salt marsh ecosystems could provide solutions for the management of regional saline soils and the protection of salt marsh wetland vegetation. A field experiment in succulent halophyte, Carex, and gramineous grass habitats in Ordos, Inner Mongolia (northwest China) was conducted to study the diversity and composition of plants in different saline habitats in inland salt marsh ecosystems. Results showed that plant diversity and species richness in the Carex habitat were significantly higher than the succulent halophyte habitat and the gramineous grass habitat (P

Soil salinity is an increasingly global problem which hampers plant growth and crop yield. Plant productivity depends on optimal water-use efficiency and photosynthetic capacity balanced by stomatal conductance. Whether and how stomatal behavior contributes to salt sensitivity or tolerance is currently unknown. This work identifies guard cell-specific signaling networks exerted by a salt-sensitive and salt-tolerant plant under ionic and osmotic stress conditions accompanied by increasing NaCl loads. We challenged soil-grown Arabidopsis thaliana and Thellungiella salsuginea plants with short- and long-term salinity stress and monitored genome-wide gene expression and signals of guard cells that determine their function. Arabidopsis plants suffered from both salt regimes and showed reduced stomatal conductance while Thellungiella displayed no obvious stress symptoms. The salt-dependent gene expression changes of guard cells supported the ability of the halophyte to maintain high potassium to sodium ratios and to attenuate the abscisic acid (ABA) signaling pathway which the glycophyte kept activated despite fading ABA concentrations. Our study shows that salinity stress and even the different tolerances are manifested on a single cell level. Halophytic guard cells are less sensitive than glycophytic guard cells, providing opportunities to manipulate stomatal behavior and improve plant productivity.

In this study, the effects of three halotolerant rhizobacterial isolates AL, HR, and SB, which are able to grow at a salinity level of 1600 mM NaCl, with multiple plant growth promoting (PGP) traits on some seed and forage quality attributes, and vegetative, reproductive, biochemical and physiological characteristics of wheat plant irrigated with saline water (0, 40, 80, and 160 mM NaCl) were investigated. The ability of halotolerant bacterial isolates to produce PGP traits was affected by salinity levels, depending upon the bacterial isolates. Salinity stress significantly affected the yield, quality, and growth of wheat by modifying the morpho-physiological and biochemical traits of the exposed plants. However, all three bacterial isolates, especially isolate AL, significantly improved the biochemical (an increase in K+/Na+ ratio by 55%, plant P content by 50%, and plant Ca content by 31%), morphological (an increase in stem dry weight by 52%, root dry weight by 44%, spike dry weight by 34%, and grain dry weight by 43%), and physiological (an increase in leaf proline content by 50% and total phenol in leaf by 42%) attributes of wheat and aided the plant to tolerate salinity stress in contrast to un-inoculated plant. Plants inoculated with bacterial isolates showed significantly improved seed amylose by 36%, leaf crude protein by 30%, leaf metabolic energy by 37%, and leaf water-soluble sugar content by 34%. Among the measured PGP and plant attributes, bacterial auxin and plant K content were of key importance in increasing reproductive performance of wheat. The bacterial isolates AL, HR, and SB were identified as Bacillus safensis, B. pumilus, and Zhihengliuella halotolerans, respectively, based on 16 S rDNA sequence. The study reveals that application of halotolerant plant growth-promoting rhizobacteria isolated from halophytic rangeland plants can be a cost effective and ecological sustainable method to improve wheat productivity, especially the attributes related to seed and forage quality, under salinity stress conditions.

The edible halophyte Mesembryanthemum crystallinum L. was grown at different NaCl salinities under different combined red and blue light-emitting diode (LED) light treatments. High salinity (500 mM NaCl) decreased biomass, leaf growth, and leaf water content. Interactions between LED ratio and salinity were detected for shoot biomass and leaf growth. All plants had Fv/Fm ratios close to 0.8 in dark-adapted leaves, suggesting that they were all healthy with similar maximal efficiency of PSII photochemistry. However, measured under the actinic light near or above the growth light, the electron transport rate (ETR) and photochemical quenching (qP) of M. crystallinum grown at 100 and 250 mM NaCl were higher than at 500 mM NaCl. Grown under red/blue LED ratios of 0.9, M. crystallinum had higher ETR and qP across all salinities indicating higher light energy utilisation. Crassulacean acid metabolism (CAM) was induced in M. crystallinum grown at 500 mM NaCl. CAM-induced leaves had much higher non-photochemical quenching (NPQ), suggesting that NPQ can be used to estimate CAM induction. M. crystallinum grown at 250 and 500 mM NaCl had higher total chlorophyll and carotenoids contents than at 100 mM NaCl. Proline, total soluble sugar, ascorbic acid, and total phenolic compounds were higher in plants at 250 and 500 mM NaCl compared with those at 100 mM NaCl. An interaction between LED ratio and salinity was detected for proline content. Findings of this study suggest that both salinity and light quality affect productivity, photosynthetic light use efficiency, and proline accumulation of M. crystallinum.

This study aims to assess the effect of five endophytic bacteria on the growth promotion of tomato plants under salt stress conditions. Twenty-five endophytic bacteria were isolated from roots of the native halophyte Stipa tenacissima L. collected from Djelfa (Algeria) and were evaluated for their halotolerant potential. Seven strong halotolerant isolates were selected and characterized for in vitro Plant Growth Promotion (PGP) including the ACC-deaminase activity, inorganic phosphate solubilization and the production of indole-3-acetic acid and siderophores. Five strains showing high PGP traits were investigated for the mitigation of salt stress and PGP of tomato (Solanum esculentum L. cv. Aicha). Screening of the salt-tolerant isolates for PGP traits in saline condition (75 mM NaCl) under Petri-dishes experiment of tomato revealed that three isolates ST09, ST18 and ST19 improved the growth of tomato seedlings by highlighting germination rate, shoot and root lengths and biomass. Under greenhouse conditions at 0 and 75 mM NaCl, inoculation of strains ST09, ST18 and ST19 in tomato seedlings produced an increase in germination (69.23%, 73.07% and 73.07%). The isolate ST19 showed an increase of more than 90% in root elongation and 17.4% increase in biomass when compared to uninoculated tomato seedlings at 75 mM NaCl stress. Phylogenetic analysis based on the 16S rRNA gene showed that the strain ST19 belongs to the genus Kocuria, and is closely related to Kocuria arsenatis |CM1E1|KM874399T (99.29% similarity). Thus, we conclude that the inoculation of tomato plants with the strain ST19 showed its efficiency to mitigate salt stress conditions.

The technique that enables simultaneous evaluation of water potential in the substomatal cavity of the intact leaf (ψwа) and rate of its photosynthetic CO2/H2O gas exchange was applied to a halophyte Suaeda altissima (L.) Pall. Formation of a water-potential gradient in a whole plant, rate of CO2 uptake, rate of transpiration, and concentrations of Na+ and Cl– ions in the plant organs were determined under conditions of chloride–sodium salinization of a nutrient solution. It was found that the salinization decreases not only biological productivity of the plants but also their capacity to accumulate Cl– in the amounts equivalent to Na+ accumulation. High salinity also diminished the gradient of water potential between a nutrient solution and the apoplast of the cells in the leaf substomatal cavity due to the increase in ψwа and, respectively, decrease in the water stream from roots to leaves and the rate of CO2/H2O gas exchange of the leaf. It was shown that the decrease in the water potential in the interface between liquid and gaseous phases in the apoplast of the substomatal cavity (expressed in the ψwа value) plays an essential role in the regulation of water uptake under salinization conditions. It is supposed that the NaCl-induced increase in ψwа is a consequence of the suppression of photosynthesis and a resultant osmolyte shortage together with the decrease in plant productivity due to the stress impact exerted by NaCl.

Background Drought is a major problem limiting the growth and development of plants in the world and especially in Tunisia. Halophytes constitute a renewable wealth and they offer great flexibility with regard to abiotic stresses, and they are evaluated for their ecological and potential food use. Results The proposed work identifies the response of Atriplex hortensis var. rubra to the germinal stage and the reproductive stage under a deficient water regime to measure the drought resistance of this plant that has very interesting forage production abilities. The morphological and water parameters are used to characterize the physiological response of this species to the effects of water deficit. For the germination test, four levels of osmotic potential caused by PEG-6000 solutions at different levels of water potential (− 0.1, − 0.5, − 1.0, − 1.5 MPa) were adopted in seed of A. hortensis germination media. The methodology adopted in the second experiment is based on the cultivation of potted plants stored in a semi-controlled greenhouse at flowering stage. The water deficit was imposed on the plants by watering stop for a week, and the control plants are subjected to a water regime maintained irrigated at 100% of the capacity in the field. Drought tolerance was scored 30 days after the drought stress commenced based on the number of branches and leaf, dry biomass, relative water content, leaf water potential, and nitrogen content. No significant difference was observed in germination rates for all PEG concentrations throughout the experiment which are still close to 60%. The results obtained for the second experiment show a high tolerance of A. hortensis under water stress. Drought induced decreases in two physiological parameters, the number of branches and leafs, and the relative water content of annual Atriplex. Heatmap and PCA data revealed that physiological parameters are more sensitive than morphological parameters in distinguishing the control and drought treatments. Conclusions Indeed, the orache is distinguished by a great ability to retain water potential after a month of stress. Thus, height, number of branches, leaf and shoot dry weight, and percentage of nitrogen were significantly similar for controls and stressed for A. hortensis. On the other hand, measured root length and basic and midday water potential show significant variability between controls and stressors. In addition, these results highlight the importance of the resistance of Atriplex halophyte forage to drought.

The wild rice Oryza coarctata (Roxb.) is an herbaceous halophytic plant belongs to the grass family poaceae prevalent to the coastal regions of Southern Asia. The O. coarctata is the only hydro-halophytic rice germplasm under the genus Oryza and shows high salinity.

Halophytes are able to survive in the high salted areas of the world, and have been recognized as sources of bioactive metabolites. There is a need to design sustainable strategies for the use of wild populations of halophytic species in order to avoid irrational gathering. Seed banks are essential for resilience and regeneration in salty ecosystems. We sampled annual seed production, aerial and soil seed banks and seed dynamics for a year in four wild populations of the annual halophyte Salicornia ramosissima growing in saltpans, in order to develop sustainable management practices for the use of its populations. The seed production of S. ramosissima depended mainly on plant density rather than on the number of seeds produced by each individual plant. In three of the four study populations, most of the annual seed production was exported out of the saltpans (> 79%) and only between 14–20% was accumulated in the initial aerial and soil seed banks. These initial seed banks were highly depleted during the year until the next fruiting period, when they accumulated less than 1% of the annual seed production (from 19 to 15302 seed m− 2). Salicornia ramosissima established a persistent soil seed bank in two of the four locations. Annual seed production would be key for the preservation of those S. ramosissima populations that do not establish persistent soil seed banks. In view of our results, each population of S. ramosissima should be studied independently to design population-specific management plans.

The diversity and plant growth-promoting ability of fungal endophytes that are associated with five halophytic plant species (Phragmites australis, Suaeda australis, Limonium tetragonum, Suaeda glauca Bunge, and Suaeda maritima) growing in the Buan salt marsh on the west coast of South Korea have been explored. About 188 fungal strains were isolated from these plant samples' roots and were then studied with the use of the internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2). The endophytic fungal strains belonged to 33 genera. Alternaria (18%) and Fusarium (12.8%), of the classes Dothideomycetes and Sordariomycetes, were most rampant in the coastal salt marsh plants. There was a higher diversity in fungal endophytes that are isolated from S. glauca Bunge than in isolates from other coastal salt marsh plants. Plant growth-promoting experiments with the use of Waito-C rice seedlings show that some of the fungal strains could encourage a more efficient growth than others. Furthermore, gibberellins (GAs) GA1, GA3, and GA9 were seen in the Sa-1-4-3 isolate (Acrostalagmus luteoalbus) culture filtrate with a gas chromatography/mass spectrometry.

This research aimed to study the fermentation of white cabbage (Brassica oleracea) replacing salt, totally or partially, with halophyte Salicornia ramosissima, to reduce the sodium content in the final products. Three fermentation trials of cabbage were done: A with 2.91% salt (similar to 1.15% Na) (control); B with salicornia (similar to 1.56% salt equivalent, similar to 0.34% Na); and C with salt and salicornia (similar to 1.94% salt equivalent, similar to 0.49% Na). The fermentation profile was followed by the physicochemical (pH, total acidity) and microbial parameters [mesophilic microorganisms (MM), lactic-acid bacteria (LAB), coliforms and fungi]. The content of phenolics and antioxidant activity in the fermented products were also measured. In all experiments, there was an increase, followed by a stabilization of the MM (5.5-7.2 Log CFU/g) and LAB populations (5.4-6.6 Log CFU/g) and a decrease of fungi and coliforms until they disappeared. A decrease in pH (< 4) and a rise in acidity (similar to 1.0%) were observed throughout the fermentations. The phenolics and antioxidant activity increased during fermentation, being significantly higher in C (37.3 mg/100 g and 3.63 mmol Trolox/100 g, respectively). The fermentation of cabbage with salicornia results in the final products having similar microbial quality to the control, but with a reduction of sodium and an increase in the antioxidant activity. FundacAo para a Ciencia e Tecnologia (FCT), Ministry of Education and Science, Portugal, through the Mediterranean Institute for Agriculture, Environment and Development (MED), Universidade do Algarve, Campus de Gambelas, Faro, Portugal [MED/UIDB/05183/2020]; Instituto Superior de Engenharia (Universidade do Algarve) info:eu-repo/semantics/publishedVersion

Background The CIPKs are a group of plant-specific Ser/Thr protein kinases acting in response to calcium signaling, which plays an important role in the physiological and developmental adaptation of plants to adverse environments. However, the functions of halophyte-derived CIPKs are still poorly understood, that limits a potential application of CIPKs from halophytes for improving the tolerance of glycophytes to abiotic stresses. Results In this study, we characterized the NtCIPK11 gene from the halophyte Nitraria tangutorum and subsequently analyzed its role in salt and drought stress tolerance, using Arabidopsis as a transgenic model system. NtCIPK11 expression was upregulated in N. tangutorum root, stem and blade tissues after salt or drought treatment. Overexpressing NtCIPK11 in Arabidopsis improved seed germination on medium containing different levels of NaCl. Moreover, the transgenic plants grew more vigorously under salt stress and developed longer roots under salt or drought conditions than the WT plants. Furthermore, NtCIPK11 overexpression altered the transcription of genes encoding key enzymes involved in proline metabolism in Arabidopsis exposed to salinity, however, which genes showed a relatively weak expression in the transgenic Arabidopsis undergoing mannitol treatment, a situation that mimics drought stress. Besides, the proline significantly accumulated in NtCIPK11-overexpressing plants compared with WT under NaCl treatment, but that was not observed in the transgenic plants under drought stress caused by mannitol application. Conclusions We conclude that NtCIPK11 promotes plant growth and mitigates damage associated with salt stress by regulating the expression of genes controlling proline accumulation. These results extend our understanding on the function of halophyte-derived CIPK genes and suggest that NtCIPK11 can serve as a candidate gene for improving the salt and drought tolerance of glycophytes through genetic engineering.

Pioneer plants play an important role in eco-engineering Fe ore tailings into soil for sustainable mine site rehabilitation. However, root-driven mineral weathering and secondary mineral formation remain poorly understood in tailings, despite being prerequisites for aggregate formation and pedogenesis. The present study aimed at characterizing the direct role of plant roots in tailing mineral weathering and secondary mineral formation in a compartmented cultivation system. It was found that root activities accelerated the weathering of biotite-like minerals via Fe(II) oxidation coupled with Fe(III) and Si dissolution. Numerous nanosized Fe–Si short-range-ordered (SRO) minerals and vermiculite were neoformed in the tailings after root interactions, as revealed by various microspectroscopic analyses. The Fe–Si-SRO minerals may have resulted from co-precipitation of dissolved Fe(III) and Si on mineral surfaces under alkaline and circumneutral pH conditions. Among the three plant species, Sorghum spp. (Gramineae plant) root developed most extensively in the tailings, possibly leading to more efficient mineral weathering and secondary mineral formation than Atriplex amnicola (halophyte plant) and Acacia chisholmii (leguminous plant). Overall, the study has elucidated the rhizosphere effects on tailing mineral (biotite dominant) weathering and secondary Fe–Si mineral formation, justifying pioneer plant roles in eco-engineering Fe ore tailings into soil.

Drought is one of the most catastrophic abiotic stress that affects global food production severely. The present work investigates the metabolic and physiological adaptation mechanisms in the xero-halophyte Haloxylon salicornicum to counter the effects of drought. This xero-halophyte can withstand a prolonged drought period of 14 days and recovered within 7 days of irrigation with minimal effects of drought on growth and physiological parameters. Photosynthetic parameters such as PN , gs, and E decreased significantly, whereas WUE increased under drought condition. Drought induces a significant decline in the Fv/Fm ratio. However, the value of Fv/Fm ratio successfully recovered within 7 days of the recovery period. Differential regulations of various antioxidative enzymes increase the drought tolerance potential of H. salicornicum. The metabolomic analysis of H. salicornicum shoot identified 63 metabolites: 43 significantly increased and 20 significantly decreased under drought conditions. These metabolites mainly include amino acids, organic acids, amines, sugar alcohols, sugars, fatty acids, alkaloids, and phytohormones. The metabolites that have a significant contribution towards drought tolerance include citric acid, malic acid, tartaric acid, D-erythrose, glyceric acid, sucrose, pentanoic acid, D-mannitol, ABA, and palmitic acid. KEGG pathway enrichment analysis showed that the vital drought-responsive metabolic pathways mainly include galactose metabolism, aminoacyl-tRNA biosynthesis, glyoxylate and dicarboxylate metabolism, citrate cycle (TCA cycle), alanine, aspartate and glutamate metabolism etc. This study offers comprehensive information on physiological, antioxidative and metabolic adaptations and overall drought tolerance mechanisms in H. salicornicum. The information gained from this study will provide guidance to plant breeders and molecular biologists to develop drought-tolerant crop varieties. This article is protected by copyright. All rights reserved.

The global annual loss in agricultural production resulting from soil salinization is significant. Although nitrate (NO3−) is known to play both nutritional and osmotic roles in the salt tolerance of halophytes, it remains unclear how halophytes such as Suaeda salsa L. take up NO3− under saline conditions. In the present study, the gene of nitrate transporter 2.1 (SsNRT2.1) was cloned from S. salsa and its function was identified in both S. salsa and Arabidopsis thaliana under salinity and low NO3−-N (0.5 mM NO3−) conditions. The results revealed that SsNRT2.1 expression and NO3− concentration in the roots of S. salsa were higher at 200 mM NaCl, compared with that at 0 and 500 mM NaCl after 24 h treatment. The Arabidopsis overexpression lines showed a higher NO3− content compared to the WT lines at 0 and 50 mM NaCl. A similar trend was observed in the root length. In conclusion, salinity promoted the SsNRT2.1 expression in S. salsa, suggesting that this gene may contribute to the efficient NO3− uptake in S. salsa under low NO3− and high salinity conditions. This trait may explain why S. salsa can tolerate high salinity and produce the highest biomass at about 200 mM NaCl.

Plant growth-promoting rhizobacteria (PGPR) can promote plant growth through mechanisms such as mineral phosphates solubilization, biological N2 fixation and siderophores and phytohormones production. The present work aims to evaluate the physiological fitness improvement by PGPR in Halimione portulacoides under mild and severe salt stress. PGPR-inoculated plants showed improved energy use efficiencies, namely in terms of the trapped and electron transport energy fluxes, and reduced energy dissipation. Allied to this, under mild stress, inoculated plants exhibited a significant reduction of the Na and Cl root concentrations, accompanied by a significant increase in K and Ca leaf content. This ion profile reshaping was intrinsically connected with an increased leaf proline content in inoculated plants. Moreover, bioaugmented plants showed an increased photoprotection ability, through lutein and zeaxanthin leaf concentration increase, allowing plants to cope with potentially photoinhibition conditions. Reduced Na leaf uptake in inoculated plants, apparently reduced the oxidative stress degree as observed by the superoxide dismutase and peroxidase activity reduction. Additionally, a reduced lipid peroxidation degree was observed in inoculated plants, while compared to their non-inoculated counterparts. These results, point out an important role of bioaugmentation in promoting plant fitness and improving salt tolerance, with a great potential for applications in biosaline agriculture and salinized soil restoration.

Crithmum maritimum L., similarly to other halophytes, could be an essential plant in marginal areas of the Mediterranean basin; it can grow with low inputs and thus tackle environmental risks of soil erosion and biodiversity caused by climate change. The leaves can be used as food because of their good chemical and nutritional parameters, as a cosmetic product and in medicine. The three treatments studied in the context of organic farming (control without input, irrigated with irrigation water only and fertigated with organic liquid fertilizer diluted in irrigation water) have provided encouraging results; in fact, regardless of the meteorological trend of the two years of experimentation, the production of aerial biomass remained at satisfactory levels and in particular, in the year following the transplantation, the production saw a significant increase in the treatments tested with low inputs (irrigated and fertigated). So, in the second year of production, a low nitrogen input with fertigation induced the plants to produce significantly more leaf biomass than the irrigated treatment, which in turn was significantly superior to the control. The production results for dry biomass are encouraging and may promote the spread of the local germplasm of this species around the Conero Park, where it is being studied to produce fermented vegetable conserves.

a succulent, halophyte, specialty vegetable, development from emergence through flowering and maturity is largely controlled by photoperiod and may be genotype-dependent. Photoperiod affects timi...

Abiotic stress effects agricultural production, so research on improving stress tolerance of crop is important. Suaeda salsa is a halophyte with high salt and drought tolerance and ability to desalinate saline soil and improve soil quality. To discover and utilize of salt and drought tolerance-related genes, we further investigated the mechanisms of salt and drought tolerance. Through screening a salt treated Suaeda salsa cDNA library and further cloning a H subunit of the photosystem I reaction center SsPsaH cDNA, and then the protein domain and phylogenetic analyses of PSI genes was conducted with the NCBI Blast, DNAMAN, and MotifScan programs. The S. salsa seedlings were subjected to various stress treatments and analyze expression of SsPsaH under these treatments by real-time RT-PCR. SsPsaH expression construct was introduced into S. pombe cells by electroporation and transformed into N. tabacum plants by the leaf disc transformation method. A member of the H subunit of the Photosystem I reaction center (defined as SsPsaH) was obtained. The expression of SsPsaH was up-regulated by abscisic acid (ABA), salt, and drought stress treatments. Over-expressing SsPsaH in recombinant yeasts enhanced high salinity tolerance and increased tolerance to sorbitol during seed germination and seedling root development in tobacco, respectively. Some stress-related mark genes such as a LEA family gene of NtLEA, a binding protein of a drought response element of NtDREB, the ascorbate peroxidase gene (NtAPX) were also up-regulated in SsPsaH overexpressing transgenic tobacco lines. These results show that SsPsaH may contribute to the salt and osmotic stress response of plants.

The leaf epidermal anatomy of 15 salt-tolerant plant species belonging to the Amaranthaceae from the Salt Range of Punjab-Pakistan was studied using light microscopy (LM). The main purpose of this ...

The effects of NaCl and abscisic acid (ABA) on selected bryophyte species were studied. Two phylogenetically unrelated halophyte mosses, namely, Entosthodon hungaricus (Boros) Loeske and Hennediella heimii (Hedw.) R.H. Zander in addition to one model non-halophyte moss, Physcomitrella patens (Hedw.) Bruch & Schimp, were selected to compare the variability in certain biochemical and physiological parameters under salt-stress alone and salt-stress upon ABA pretreatment. The results showed different patterns of effects from ABA in all three of the studied species, as well as no common response to salt stress. In general, all of the tested species reacted to exogenous ABA, which definitely contributed to changes observed in morphological development under salt stress, and to the functioning of the salt-tolerance mechanisms. Physcomitrella patens proved to be a salt-tolerant species. Although it is not ecologically classified as a halophyte, these results highlighted that various stress-resistance pathways are supported by similar reactions to different stresses. Significant differences in stress tolerance were documented between the two bryo-halophytes tested by comparing biochemical and physiological parameters. Our findings suggest that different salt-stress-tolerance strategies characterize these two species, both enhanced by exogenous ABA.

We investigated changes in the growth parameters, sodium accumulation, element composition, and antioxidant enzyme activity of habitat-indifferent Salsola drummondii Ulbr. during the vegetative stage. Our results show that S. drummondii grows very well in salt concentrations up to 500 mmol/L NaCl. There were no significant differences in the water content and biomass of shoots, roots, and leaves between the control and plants treated with 500 mmol/L NaCl (equivalent to the salinity of seawater). However, chlorophyll and carotenoid content was reduced at higher salinities, which was associated with a significant increase in H2O2 and malondialdehyde. Our results revealed that S. drummondii can translocate Na+ from the roots to the shoots, with Na+ content in the shoots being higher than that in the roots. In contrast, the S. drummondii plants treated with NaCl exhibited a significant decrease in the levels of essential ions in different plant organs. Proline concentration significantly increased with increasing salinity, and significant changes were observed in guaiacol peroxidase, catalase, and ascorbate peroxidase levels under different salinity treatments. The activity of antioxidant enzymes and proline accumulation in S. drummondii plants correlated with enhanced salt tolerance. Our findings provide novel insights into the salt tolerance of S. drummondii.

The effects of changes in auxin transport in response to different osmotic potentials (Ψo) were analyzed in the roots and leaves of two leguminous species with different degrees of salt tolerance: the halophyte Prosopis strombulifera (Lam.) Benth. and the glycophyte Glycine max L. The potentials were generated with sodium chloride (NaCl), sodium sulfate (Na2SO4), and the iso-osmotic mixture of both salts (NaCl + Na2SO4). The values evaluated were −1, −1.8, and −2.6 MPa for P. strombulifera, and −0.47, −0.69, and −0.87 MPa for G. max. In addition, the plants were sprayed with 2,3,5-triiodobenzoic acid (TIBA), an auxin transport inhibitor. The parameters measured included root length, shoot height, number of leaves, relative membrane permeability in roots, and endogenous levels of abscisic acid (ABA), indole-3-acetic acid (IAA), and zeatin (Z). Significant responses were observed at the lowest potentials evaluated (−2.6 MPa for P. strombulifera and −0.89 MPa for G. max). Treatment with Na2SO4 inhibited plant growth more than the others, increased the relative membrane permeability, and enhanced ABA production to its highest levels. These toxic effects were slightly reversed in the presence of iso-osmotic mixture. TIBA brought about impaired development in shoots and roots, the highest values for membrane permeability, alterations in the distribution of endogenous ABA, IAA, and Z, as well as harmful effects on the growth response of both species. In general, the alterations in auxin transport intensified the effects of salinity, which confirms the essential role of this mechanism in plants under salt stress or in normal, non-stressful conditions.

Salinity is a growing issue worldwide, with nearly 30% of arable land predicted to be lost due to soil salinity in the next 30 years. Many grass crops that are vital to sustain the world’s caloric intake are salt sensitive. Studying mechanisms of salt tolerance in halophytic grasses, plants that thrive in salt conditions, may be an effective approach to ultimately improve salt-sensitive grass crops. Seashore paspalum (Paspalum vaginatum) is a halophytic Panicoid grass able to grow in salt concentrations near that of seawater. Despite its widespread cultivation as a sustainable turfgrass, the mechanism underlying its ability to retain high Na(+) concentrations in photosynthetic tissue while maintaining growth remains unknown. We examined the leaf structure and ion content in P. vaginatum ‘HI10’, which shows increased growth under saline conditions, and Paspalum distichum ‘Spence’, which shows reduced growth under salt, to better understand the superior salt tolerance of cv HI10. A striking difference between cv HI10 and cv Spence was the high steady-state level of K(+) in cv HI10. Imaging further showed that the adaxial surface of both cv HI10 and cv Spence contained dense costal ridges of papillae. However, these unicellular extensions of the epidermis were significantly larger in cv HI10 than in cv Spence. The cv HI10 papillae were shown to act as Na(+) sinks when plants were grown under saline conditions. We provide evidence that leaf papillae function as specialized structures for Na(+) sequestration in P. vaginatum, illustrating a possible path for biotechnological improvement of salt-sensitive Panicoid crops with analogous leaf structures.

Low availability of inorganic phosphate (Pi) in soil is often a limiting factor for plant growth and productivity. The Pi transporter plays an important role in the absorption and utilization of phosphorus in plants. Eutrema salsugineum shows strong tolerance under Pi stress conditions, but the function of the E. salsugineum PHT1 genes has not yet been systematically studied. This study isolated a phosphate transporter gene (EsPHT1;1) from the halophyte E. salsugineum and functionally characterized it in the herbaceous model plant, Arabidopsis thaliana, and in an important oil crop species, soybean (Glycine max (L.) Merr.). Under Pi deficient conditions, transgenic Arabidopsis and transgenic soybean grew better and exhibited significant improvement in root growth, biomass accumulation and seed yield compared with wild-type (WT) plants. These phenotypic enhancements were more apparent under inadequate Pi conditions than under sufficient or no Pi conditions, which is in agreement with the observation that the transgenic plants accumulated higher amounts of Pi and total P in shoots and roots than WT plants only when inadequate Pi was supplied. The results of the present study indicate that overexpression of EsPHT1;1 can efficiently enhance the growth and reproductive performance of both Arabidopsis and soybean plants challenged by low P stress, which results confirm the important role of PHT1;1 in dealing with Pi deficiency.

Endophytic bacteria of halophytic plants play essential roles in salt stress tolerance. Therefore, an understanding of the true nature of plant—microbe interactions under extreme conditions is essential. The current study aimed to identify cultivable endophytic bacteria associated with the roots and shoots of Seidlitzia rosmarinus Ehrenb. ex Boiss. grown in the salt-affected soil in Uzbekistan and to evaluate their plant beneficial traits related to plant growth stimulation and stress tolerance. Bacteria were isolated from the roots and the shoots of S. rosmarinus using culture-dependent techniques and identified by the 16S rRNA gene. RFLP (Restriction Fragment Length Polymorphism) analysis was conducted to eliminate similar isolates. Results showed that the isolates from the roots of S. rosmarinus belonged to the genera Rothia, Kocuria, Pseudomonas, Staphylococcus, Paenibacillus and Brevibacterium. The bacterial isolates from the shoots of S. rosmarinus belonged to the genera Staphylococcus, Rothia, Stenotrophomonas, Brevibacterium, Halomonas, Planococcus, Planomicrobium and Pseudomonas, which differed from those of the roots. Notably, Staphylococcus, Rothia and Brevibacterium were detected in both roots and shoots, indicating possible migration of some species from roots to shoots. The root-associated bacteria showed higher levels of IAA (indole-3-acetic acid) synthesis compared with those isolated from the shoots, as well as the higher production of ACC (1-aminocyclopropane-1-carboxylate) deaminase. Our findings suggest that halophytic plants are valuable sources for the selection of microbes with a potential to improve plant fitness under saline soils.

Sexual reproduction, a critical life history process in plants, can be altered by heat stress derived from global warming. Sexual reproduction increases genetic diversity, and the ability of plants to respond to environmental changes and dispersal. The capacity for these responses is especially relevant as plants are exposed to rising environmental stress levels imposed by climate change. We investigated the influence of environmental factors that impose physiological stress that may affect the fruit set of Spartina maritima, the sole native African and European cordgrass species. To achieve our objective, we acquired locally recorded air temperatures and tidal amplitude projections. Within population sites, we measured sedimentary conditions (pH, redox potential and electrical conductivity), and the phenological stage of S. maritima inflorescences, spikelets with non-exserted stamens and caryopses produced throughout its 10-week flowering period. Fruit set decreased as flowering period advanced, and as air temperatures and the proportion of spikelets with non-exserted stamens increased. Fruit set decreased with increased sediment anoxia. The proportion of reabsorbed caryopses increased with high air temperatures during the female phase of the inflorescence, and with higher tidal amplitudes during the male phase. These environmental stress factors could terminate caryopsis development that had commenced. Our results point to a severe potential impact of global warming on the reproductive process of native S. maritima. Mitigation of global warming will be essential to maintain population persistence and support conservation and recovery of this halophyte that provides important ecosystem services in salt marshes.

DOR: 98.1000/2383-1251.1399.7.181.13.1.1588.1610 Extended abstract Introduction: Camelthorn (Alhagi maurorum) has a high tolerance to salt and water stresses, and its forage quality is greater than cereal straw and is equal to alfalfa. Seeds of camelthorn do not germinate easily due to the hard seed coat. Therefore, camelthorn cultivation as an agricultural crop needs more research, especially on breaking seed dormancy and increasing germination. Despite numerous studies about camelthorn as a weed, there are few studies on evaluating agronomic factors of camelthorn as a field crop. Hence, in this study, some aspects of germination and salinity tolerance of camelthorn were examined. Materials and Methods: In this research, different aspects of camelthorn germination were examined at the National Salinity Research Center in 2018. In the first experiment, different pretreatments including control, sandpaper, hydro-priming, hot water, and sulphuric acid were assessed. With the selection of sulphuric acid as the best treatment, varying durations (0, 5, 10, 15, 20, and 25 min) and concentrations (98% and 75%) of sulphuric acid priming were compared in the second and third experiments. In the fourth experiment, the seeds collected in 2018 were compared with the seeds collected in 2017 and 2016. The effect of different salt stress levels (0, 6, 12, 18, 24, 30, and 36 dS m-1) was evaluated on camelthorn germination and early growth in the fifth experiment. In the sixth experiment, lighting regimes including continuous dark, continuous light, and an alternative period of dark- light were examined and in the seventh experiment sibling factors (together and individual seeds) were evaluated. Seed germination and seedling length were calculated and salinity tolerance threshold levels and 50% reduction threshold were estimated. Results: The results of the first experiment showed that the highest germination percentage was obtained in sulphuric acid priming (56.6%), which was six folds greater than the control. In the second experiment, it was shown that the highest germination percentage (81.1%) and seedling growth (5.7 cm) was observed in sulphuric acid priming 98% for 25 min. Important note was that these results were related to domestically produced sulphuric acid, and the highest germination and seedling growth were observed in 75% concentration for the imported sulphuric acid. In the fourth experiment, it was found that at least 3 years of seed longevity had no significant effect on seed germination. Considerable losses in germination and growth were observed from 30 dS m-1 salinity level; however, germination did not completely stop even at 36 dS m-1 salinity. In the sixth and the seventh experiments, it was found that there were no significant differences between seeds germination in the continuous dark, continuous light, and an alternative period of dark- light as well as between individual and together seeds. So, camelthorn seed is not photoblastic and had no negative sibling factor. Conclusions: Generally, it was concluded that the best method for improving germination is priming with sulphuric acid 98% (internal) or 75% (imported) for 25 min. According to achievement of high germination in sulphuric acid pre-treatments (chemical scarification), it seems that seed dormancy in camelthorn is presumably physical. Furthermore, although the salinity tolerance threshold of this plant is estimated 14.2 dS m-1, it can germinate minimally even in very higher salinity. Light salt stress not only decreases the germination of this plant but also is necessary for growth promoting. Based on the high salinity tolerance of camelthorn in the germination stage, its cultivation in haloculture systems is recommended for more investigation. Highlights: 1- Sulphuric acid 98% priming for 25 min led to breaking seed dormancy and acceptable camelthorn germination. 2- In moderate salinity, germination was not significantly changed and seedling growth was promoted compared with the non-stress conditions. 3- Salinity tolerance threshold level of camelthorn was estimated 14.2 dS m-1.

Heavy metal polluted soils can be remediated using plants, a process called phytoremediation. However, high concentrations of heavy metals can negatively affect plant physiology and growth. We expe...

A pot experiment was carried out to study the ameliorative role of foliar application of an extract of the halophyte Arthrocnemum macrostachyum (A. macrostachyum) on soybean (Glycin max L.) plants grown under salinity stress (0, 75, and 150 mM NaCl). Growth traits, content of photosynthetic pigments, osmolytes, ascorbic acid and total phenol, oxidative damage, and proteins pattern were determined. Growth parameters of soybean plants grown under both saline regimes (75 and 150 mM NaCl) were reduced except for the response to the foliar application of A. macrostachyum extract in either stressed or non-stressed plants. Foliar application of A. macrostachyum extract reinforced the photosynthetic pigment, soluble sugars, and soluble proteins content. Besides, it also minimized the negative impacts of salinity on soybean plants by decreasing the content of malondialdehyde (MDA) and hydrogen peroxide (H2O2). The results herein showed that the plant water extract and their interactions in the two NaCl levels increased the proline, total free amino acids, total phenols, and ascorbic acid content. Protein patterns in soybean leaves indicated protein expression suppression in soybean plants irrigated with 150 mM NaCl. The magnitude of suppression caused by the saline level was enhanced by using A. macrostachyum extract. The findings of this study indicate that the use of an extract of the halophyte A. macrostachyum can be considered as an unconventional and novel tool in the mitigation of salinity stress.

Germination and especially emergence can decrease significantly with depth. Our main goal was to examine the effects of sand burial depth on seed germination and seedling establishment of two halop...

Phytostabilization of metal enriched substrates in arid and semiarid areas depends on the use of metal-tolerant or metallophyte plants in order to decrease metal mobilization and dispersion. However, the co-occurrence of other abiotic restrictions on plant growth, such as drought and salinity calls for a new perspective for plant selection. Since components of salt and drought tolerance traits of halophytes are also present in metal stress, Atriplex species, typical of dry and salty soils, emerge as good candidates for phytostabilization. But in order to confirm this potential, it is necessary to explore specific responses to increasing copper, salt and water stress. In this study, we compared the effect of single and combined copper, NaCl and PEG- induced water stresses on growth parameters of the Chilean Atriplex atacamensis, European A. halimus and Australian A. nummularia under controlled hydroponic assays. Results showed that increasing copper had severe effects on root development of all three species, with subsequent effects on their shoot biomass. Salt stress effects were mostly osmotic, with a decrease in shoot fresh weight and water content, and PEG- induced water stress had no clear effect on growth of roots and shoots. Combination of copper with NaCl and PEG further decreased plant growth, but this effect varied among Atriplex species. This shows that growth of Atriplex species responds differently to each individual stress and that stressor combination causes an overall negative effects in their growth parameters.

Kallar grass (Leptochloa fusca) is a highly salt-tolerant C4 perennial halophytic forage. The regulation of ion movement across the plasma membrane (PM) to improve salinity tolerance of plant is thought to be accomplished with the aid of the proton electrochemical gradient generated by PM H+-ATPase. In this study, we cloned a partial gene sequence of the Lf PM H+-ATPase and investigated its expression and activity under salt stress. The amino acid sequence of the isolated region of Lf PM H+-ATPase possesses the maximum identity up to 96% to its ortholog in Aeluropus littoralis. The isolated fragment of Lf PM H+-ATPase gene is a member of the subfamily Π of plant PM H+-ATPase and is most closely related to the Oryza sativa gene OSA7. The transcript level and activity of the PM H+-ATPase were increased in roots and shoots in response to NaCl and were peaked at 450 mM NaCl in both tissues. The induction of activity and gene expression of PM H+-ATPase in roots and shoots of Kallar grass under salinity indicate the necessity for this pump in these organs during salinity adaptation to establish and maintain the electrochemical gradient across the PM of the cells for adjusting ion homeostasis.

Roots provide physical and nutritional support to plant organs that are above ground and play critical roles for adaptation via intricate movements and growth patterns. Through screening the effects of bacterial isolates from roots of halophyte Mesquite (Prosopis sp.) on Arabidopsis thaliana, we identified Achromobacter sp. 5B1 as a probiotic bacterium that influences plant functional traits. Detailed genetic and architectural analyses in Arabidopsis grown in vitro and in soil, cell division measurements, auxin transport and response gene expression and brefeldin A treatments demonstrated that root colonization with Achromobacter sp. 5B1 changes the growth and branching patterns of roots, which were related to auxin perception and redistribution. Expression analysis of auxin transport and signaling revealed a redistribution of auxin within the primary root tip of wild-type seedlings by Achromobacter sp. 5B1 that is disrupted by brefeldin A and correlates with repression of auxin transporters PIN1 and PIN7 in root provasculature, and PIN2 in the epidermis and cortex of the root tip, whereas expression of PIN3 was enhanced in the columella. In seedlings harboring AUX1, EIR1, AXR1, ARF7ARF19, TIR1AFB2AFB3 single, double or triple loss-of-function mutations, or in a dominant (gain-of-function) mutant of SLR1, the bacterium caused primary roots to form supercoils that are devoid of lateral roots. The changes in growth and root architecture elicited by the bacterium helped Arabidopsis seedlings to resist salt stress better. Thus, Achromobacter sp. 5B1 fine tunes both root movements and the auxin response, which may be important for plant growth and environmental adaptation.

Salinity adversely affects growth and yield of crop plants. Plants respond to salinity using a series of physiological and biochemical mechanisms through an orchestrated regulation of many genes. Halophyte species have attracted attention of plant biologists to explore their salinity tolerance mechanisms. This knowledge may provide novel routes to improve salinity stress tolerance in crop plants resulting in higher sustainable yields. Salicornia persica is an Iranian native halophyte species that can tolerate extreme salinity. We performed Illumina high-throughput RNA sequencing and functional annotation on shoots of S. persica under control and salinity conditions to investigate the molecular mechanisms controlling salinity adaptation in this halophyte. Over 68 million and 65 million clean reads were generated from control and salinity-treated libraries, respectively. We identified 1595 differentially expressed genes including several transcription factors, protein kinases and transporters. Functional annotation analysis suggested that energy homeostasis and synthesis of primary metabolites play key roles for salinity adaptation in S. persica. Furthermore, gene network analysis indicated that abscisic acid and calcium signaling as well as sodium compartmentalization are major components to confer tolerance to salinity in S. persica. This first report on transcriptome analysis of the halophyte S. persica provided insight into the mechanisms underlying salinity tolerance and served as a platform for future studies.

Atriplex canescens is a C4 shrub with excellent adaptation to saline and arid environments. Our previous study showed that the secretion of excessive Na+ into leaf salt bladders is a primary strategy in salt tolerance of A. canescens and external 100 mM NaCl can substantially stimulate its growth. To investigate whether NaCl could facilitate Atriplex canescens response to drought stress, five-week-old seedlings were subjected to drought stress (30% of field water capacity) in the presence or absence of additional 100 mM NaCl. The results showed that, under drought stress, the addition of NaCl could substantially improve the growth of A. canescens by increasing leaf relative water content, enhancing photosynthetic activity and inducing a significant declined leaf osmotic potential (Ψs). The addition of NaCl significantly increased Na+ concentration in leaf salt bladders and the Na+ contribution to leaf Ψs, while had no adverse effects on K+ accumulation in leaf laminae. Therefore, the large accumulation of Na+ in salt bladders for enhancing osmotic adjustment (OA) ability is a vital strategy in A. canescens responding to drought stress. In addition, the concentration of free proline, bataine and soluble sugars exhibited a significant increase in the presence of NaCl under drought stress, and the betaine contribution to leaf Ψs was significantly increased by additional NaCl compared with that under drought treatment alone, suggesting that compatible solutes are also involved in OA in addition to functioning as protectants to alleviate water deficit injury.

In this study, the response of the chloroplastic antioxidant system of the halophyte Cakile maritima Scop. and its tolerance to NaCl stress have been studied using purified chloroplasts. Seedlings were grown in different salt concentrations (0, 100, 200 and 400 mmol/L NaCl) and plants were harvested after 40 days. Isolated chloroplasts were purified by centrifugation in density-gradients of Percoll. The evaluation of the oxidative stress was analysed measuring lipid peroxidation, carbonyl protein, $${\text{O}}_{2}^{ - }$$ and H2O2 contents and the antioxidant status by measurement of the activities of superoxide dismutase, catalase, peroxidase and enzymes of the ascorbate–glutathione cycle as well as the antioxidants ascorbate and glutathione, in the purified chloroplasts. Results revealed that the best growth response of C. maritima under moderate salt stress was associated with a low oxidative stress, the highest activities of SOD, POD and APX and the highest glutathione content. The interaction between the water status of the plant and mineral nutrition seems to be strongly involved in the plant performance under salinity.

Limoniastrum monopetalum is a perennial halophyte growing at different habitats along the Mediterranean Sea coast of Egypt. The morpho-anatomical and physiological responses was investigated for L. monopetalum leaves collected from; wet salt marshes, coastal sand dunes and rocky ridges habitats. The plant acquired the highest values of leaf area, lamina thickness, specific leaf area and water content despite of the high salinity in the salt marshes habitat. Additionally, plant is able to regulate content of Na+, Cl−, K+, Ca2+, Mg2+, accumulate proline and total phenols. On the other hand, plants growing in the driest habitats (coastal sand dunes and rocky ridges) acquired xeromorphic features viz., thick cuticle, compacted palisade tissue, increasing lignification of sclerified tissue and ash content. Moreover, plants in coastal sand dunes displayed extra adaptive responses viz., increase in chl. a, chl. b, carotenoids, K+ and Cl−, palisade ratio and stomatal densities. Plants growing at rocky ridges were affected by drought and salinity together. Those acquired the highest Na+ and Na+/K+, associated with the lowest in osmotic potential. In general, L. monopetalum able to exclude salt outside cells via salt glands scattered on leaf surfaces. These mechanisms permit L. monopetalum to tolerate and survive under stressful coastal habitats of Egypt.

Background Puccinellia tenuiflora, a forage grass, is considered a model halophyte given its strong tolerance for multiple stress conditions and its close genetic relationship with cereals. This halophyte has enormous values for improving our understanding of salinity tolerance mechanisms. The genetic information of P. tenuiflora also is a potential resource that can be used for improving the salinity tolerance of cereals. Results Here, we sequenced and assembled the P. tenuiflora genome (2n = 14) through the combined strategy of Illumina, PacBio, and 10× genomic technique. We generated 43.2× PacBio long reads, 123.87× 10× genomic reads, and 312.6× Illumina reads. Finally, we assembled 2638 scaffolds with a total size of 1.107 Gb, contig N50 of 117 kb, and scaffold N50 of 950 kb. We predicted 39,725 protein-coding genes, and identified 692 tRNAs, 68 rRNAs, 702 snRNAs, 1376 microRNAs, and 691 Mb transposable elements. Conclusions We deposited the genome sequence in NCBI and the Genome Warehouse in National Genomics Data Center. Our work may improve current understanding of plant salinity tolerance, and provides extensive genetic resources necessary for improving the salinity and drought tolerance of cereals.