Detrimental Effects Of Salt Stress Research Articles

Dopamine Hydrochloride Alleviates the Salt-induced Stress in Glycine max (L.) Merr. plant

AbstractThe objective of this study is to evaluate the role of dopamine hydrochloride (DH) in alleviating the detrimental effects of salt stress on Glycine max (L.) plant. Soybean seeds were treated with 150 mM NaCl and DH (100 µM or 200 µM) after they had been grown in plastic pots then the growth parameters, physiological and molecular analyses were assessed. Data showed that salinity stress decreased the germination percentage by 63.6%, the tolerance index (TI) and the seedling vigor index (SVI) were highly decreased. Salinity stress led to a markedly decline in the photosynthetic efficiency and the content of chlorophyll a and chlorophyll b by 43.5%, 77.4% and 44.6%, respectively. Salinity stress increased MDA and activity of CAT, SOD, POD, APX, GST and GR by 150%, 39.8%, 75%, 160%, 77.7%, 50% and 57%, respectively. However, DH (100 µM or 200 µM) significantly alleviated the toxic effects of salinity stress, marinated ions absorption, and enhanced the molecular level. Wherein out of 30 ISSR amplified fragments were formed. There were 10 unique bands (587 bp, 453 bp, 393 bp, 435 bp, 157 bp, 679 bp, 473 bp, 675 bp, 758 bp and 531 bp) were appeared in response to DH (100 µM and 200 µM) compared with untreated plants. Our analysis suggests a constructive effect of DH (100 µM and 200 µM) in alleviating the toxic effects of salinity stress on Glycine max (L.) plant not only at the level of antioxidative defense but also by regulating the molecular response highlighting the potential use of DH to improve the sustainability of horticultural production under climate change.

Ácido salicílico reduz os efeitos prejudiciais do estresse salino em Tropaeolum majus

ABSTRACT Salt stress hampers the growth and physiology of nasturtium (Tropaeolum majus), due to biochemical, physiological, and anatomical disruptions. The application of salicylic acid stands as an alternative to alleviate the detrimental effects of salt stress, but studies on nasturtium are scarce. Thus, the aim of present study was to assess the effects of foliar application of salicylic acid on nasturtium cultivated under salt stress. The experiment followed a completely randomized design in a 3 x 3 factorial scheme, with 0 (no stress), 50 (moderate salt stress), and 100 (severe salt stress) mM of NaCl, and application of 0, 0.5, and 1 mM of salicylic acid, each with six replications. Growth (plant height, stem diameter, and number of leaves), gas exchange (stomatal conductance, photosynthesis, transpiration, internal CO2 concentration, intrinsic water use efficiency, instantaneous water use efficiency, and intrinsic carboxylation efficiency), as well as chlorophyll indices and chlorophyll a fluorescence were evaluated. Salt stress affected the variables analyzed in this study. The application of salicylic acid had a positive effect on mitigating the effects of severe salt stress, resulting in a significant increase in the number of leaves. The most effective dose was 1 mM, also leading to notable improvements in water use efficiency and photochemical efficiency. However, other combinations of salinity and salicylic acid reduced growth and gas exchange in nasturtium plants.

The Role of Salt-Tolerant Crops in the Proper Use of Saline Soils

The use of saline soils for agricultural production is a major challenge. A study investigated the resistance to salinity, yield, and product quality of five crops (alfalfa, sunflower, white sorghum, sorghum, and millet) grown on weak, moderate, and strongly saline soils in Uzbekistan. The results showed that the crops were more resistant to salinity on weak and moderate soils than on strongly saline soils. The highest yields were obtained on weak soils, while the lowest yields were obtained on strongly saline soils. The product quality of the crops was also affected by salinity, with the best quality being obtained on weak soils. The study provides valuable insights into the use of saline soils for agricultural production. Saline stress has been the one of the biggest hurdles in achieving the demand and supply ratio of global population. To combat the growing problem of soil salinity, advanced soil management and irrigation technology are used. However, they are cost and energy intensive. Plant growth promoting rhizobacteria (PGPR) attained from saline soils can overcome the detrimental effects of salt stress on plants. PGPR positively impact physiological functions of plants such as growth, yield and overcome disease resistance. T

Chemical Interventions to Alleviate Salt Stress in Cotton Plants: A Review

The alleviation of salt stress in cotton plants through the application of exogenous chemicals has emerged as a viable strategy to mitigate the adverse effects on various plant attributes, including growth, development, yield, and flowering. Plant hormones, known for their efficacy at low doses, have garnered significant attention in this context. Despite being inherently susceptible to salt stress, cotton plants experience severe impediments in water absorption from the soil, leading to delayed growth and development. Several phytohormones, including jasmonic acid, salicylic acid, and glycine betaine, have been extensively investigated in numerous studies for their potential to ameliorate salt stress in cotton plants. Promising results have been obtained with both foliar and seed treatments employing these substances. This foundational knowledge has paved the way for the development of alternative strategies to mitigate salt stress. However, the practical utilization of these chemicals is hindered by their elevated cost. Plant growth regulators, such as nitric oxide and melatonin, have also garnered interest for their ability to alleviate salt stress in cotton plants. Numerous studies have corroborated their effectiveness in this regard. This review comprehensively examines the aforementioned substances and extracts that have been investigated for their potential to mitigate the detrimental effects of salt stress on cotton plants.

Rhizobacterial Isolates from Prosopis limensis Promote the Growth of Raphanus sativus L. Under Salt Stress

Microbial biotechnology employes techniques that rely based on the natural interactions that occur in ecosystems. Bacteria, including rhizobacteria, play an important role in plant growth, providing agricultural crops with an alternative that can mitigate the negative effects of abiotic stress, such as those caused by saline environments. In this study, bacterial isolates were obtained from soil and roots of Prosopis limensis Bentham from the department of Lambayeque, Peru. This region has high salinity levels, therefore, the collected samples were used to isolate plant growth-promoting rhizobacteria (PGPR), which were identified through morphological, and physical-biochemical characteristics. These salt tolerant bacteria were screened phosphate solubilization, indole acetic acid, deaminase activity and molecular characterization by 16S rDNA sequencing. Eighteen samples from saline soils of the Prosopis limensis plants in the northern coastal desert of San Jose district, Lambayeque, Peru. The bacterial isolates were screened for salt tolerance ranging from 2 to 10%, a total of 78 isolates were found. Isolates 03, 13 and 31 showed maximum salt tolerance at 10%, in vitro ACC production, phosphate solubilization and IAA production. The three isolates were identified by sequencing the amplified 16S rRNA gene and were found to be Pseudomonas sp. 03 (MW604823), Pseudomonas sp. 13 (MW604824) and Bordetella sp. 31 (MW604826). These microorganisms promoted the germination of radish plants and increased the germination rates for treatments T2, T3 and T4 by 129, 124 and 118% respectively. The beneficial effects of salt tolerant PGPR isolates isolated from saline environments can be new species, used to overcome the detrimental effects of salt stress on plants. The biochemical response and inoculation of the three isolates prove the potential of using these strains as a source of products that can be employed for the development of new compounds proving their potential as biofertilizers for saline environments.

Insights into the Detrimental Impacts and Coping Mechanisms under Salinity Stress in Mungbean (Vigna radiata L.)

Global food production is seriously threatened by salinity stress, which is becoming more severe due to human activity. For the majority of people worldwide, mungbean is a significant pulse crop and a rich source of protein and calories and hence is rightly marked as “Poor man’s meat” and “rich man’s vegetables”. Salt stress, on the other hand, negatively affects the productivity of the mungbean since it causes decreased germination, reduced growth and development, interrupted photosynthesis, hormonal imbalance and eventually decreased yields. Consequently, developing mitigation strategies to deal with salt stress requires a greater understanding of how plants respond to salinity stress. The present review highlights the detrimental effects of salt stress and the physiological and biochemical tolerance mechanisms in mungbean.

Comparative analysis of microRNA expression profiles in shoot and root tissues of contrasting rice cultivars (Oryza sativa L.) with different salt stress tolerance.

Rice is the second-most important primary crop in the world and one of the most susceptible crops to salt stress. Soil salinization hinders seedling growth and decreases crop yield by inducing ionic and osmotic imbalances, photosynthesis disturbances, cell wall alterations, and gene expression inhibition. Plants have developed a range of defense mechanisms to adapt to salt stress. One of the most effective means is to make use of plant microRNAs (miRNAs) as post-transcriptional regulators to regulate the expression of developmental genes in order to mitigate the detrimental effects of salt stress. In this study, the miRNA sequencing data between two contrasting rice cultivars, salt-tolerant Doc Phung (DP) and salt-sensitive IR28 seedlings, were compared under control and salt stress (150 mM NaCl) conditions to determine the salt stress-responsive miRNAs. Comparative analysis of miRNA sequencing data detected a total of 69 differentially expressed miRNAs in response to salt stress treatment. Among them, 18 miRNAs from 13 gene families, MIR156, MIR164, MIR167, MIR168, MIR171, MIR396, MIR398, MIR1432, MIR1846, MIR1857, MIR1861, MIR3979, and MIR5508, were identified to be specifically and significantly expressed in the shoot and root tissues of DP seedlings. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses further revealed that these detected miRNAs regulate a range of essential biological and stress response processes, including gene transcription, osmotic homeostasis, root formation, ROS scavenger synthesis, and auxin and abscisic acid signaling pathways. Our findings provide more insight into the miRNA-mediated responsive mechanisms of rice under salt stress and should benefit the improvement of salt stress tolerance in rice.

Effect of Exogenous Salicylic Acid and Silicon Application on Salinity Tolerance of Rice

Soil salinity remarkably hinders rice growth, development and productivity. The present study was set up to explore the role of exogenous salicylic acid (SA) and silicon (Si) application on the growth and yield performance of two contrasting rice genotypes, namely BRRI dhan41 (salt-tolerant) and BRRI dhan49 (salt-sensitive) under salinity. The experiment was laid out in a randomized complete block design with three replications and four SA and Si treatments such as control (tap water), 100 ppm SA, 100 ppm Si (as CaSiO3) and, co-application of SA and Si (50 ppm each). Results revealed that the maximum plant height (125.2 cm), fresh weight of shoot (267.3 g) and maximum K+/Na+ (5.2) were obtained in BRRI dhan49 after sole application of Si under salt stress. Besides, the number of grains per panicle and grains per hill significantly increased in BRRI dhan41 after the sole application of SA (64 and 46%, respectively) and co-application of SA and Si (29 and 21%, respectively), and in BRRI dhan49 with sole SA (182 and 277%, respectively) and Si (75 and 446%, respectively) compared with their respective controls. Besides, we observed that the K+/Na+ was increased where the shoot accumulation of Na+ reduced significantly in both rice varieties after sole and co-application of SA and Si compared with the untreated plants. However, the present findings showed new dimensions regarding the beneficial effects of Si on rice plants which could effectively be utilized to grow and maximize rice production in the saline-prone coastal areas of Bangladesh encountering detrimental effects of salt stress on rice.
 Bangladesh Agron. J. 2022, 25(2): 119-127

Sustaining nitrogen dynamics: A critical aspect for improving salt tolerance in plants.

In the current changing environment, salt stress has become a major concern for plant growth and food production worldwide. Understanding the mechanisms of how plants function in saline environments is critical for initiating efforts to mitigate the detrimental effects of salt stress. Agricultural productivity is linked to nutrient availability, and it is expected that the judicious metabolism of mineral nutrients has a positive impact on alleviating salt-induced losses in crop plants. Nitrogen (N) is a macronutrient that contributes significantly to sustainable agriculture by maintaining productivity and plant growth in both optimal and stressful environments. Significant progress has been made in comprehending the fundamental physiological and molecular mechanisms associated with N-mediated plant responses to salt stress. This review provided an (a) overview of N-sensing, transportation, and assimilation in plants; (b) assess the salt stress-mediated regulation of N dynamics and nitrogen use- efficiency; (c) critically appraise the role of N in plants exposed to salt stress. Furthermore, the existing but less explored crosstalk between N and phytohormones has been discussed that may be utilized to gain a better understanding of plant adaptive responses to salt stress. In addition, the shade of a small beam of light on the manipulation of N dynamics through genetic engineering with an aim of developing salt-tolerant plants is also highlighted.

Effect of exogenous taurine on pea (Pisum sativum L.) plants under salinity and iron deficiency stress

Soil salinity and Fe deficiency affect plant growth and survival by changing nutrient availability and disrupting water balance. Natural and human activities, such as evaporation and deforestation, can intensify these soil conditions. Taurine, a novel growth regulator, holds promise in mediating plant defense responses. Its effects on defense responses are still unclear. Previously, taurine showed potential in improving clover tolerance to alkaline stress and manganese toxicity. Taurine impact on plant growth under Fe deficiency and salinity stress remains uninvestigated. A pot experiment was conducted to evaluate the effects of taurine on pea plant growth, ion uptake, and defense strategies in response to salt stress and Fe deficiency. Iron deficiency was established by substituting 0.1 mM FeSO4 for 0.1 mM Fe-EDTA in the nutrient solution. Salinity stress was induced by incorporating a mixture of NaCl, MgCl2, KCl, Na2SO4, Na2CO3, NaHCO3 and CaCl2 in a 1:1:1:1:1:1:1 ratio to produce a salinity concentration of 100 mM. The simultaneous imposition of salinity and Fe deficiency significantly exacerbated oxidative stress, as evidenced by elevated levels of relative membrane permeability, hydrogen peroxide (H2O2), superoxide radical (O2•−), methylglyoxal (MG), malondialdehyde (MDA), and increased activity of lipoxygenase (LOX). Salinity stress alone and the combination of salinity and Fe deficiency resulted in substantial accumulation of Na+ ions that impeded acquisition of essential nutrients. Taurine (100 and 200 mg L−1) notably improved osmotic adjustment and oxidative defense to diminish water imbalance and oxidative injury in plants under stress. These results suggest that exogenous taurine may serve as a promising means of mitigating the detrimental effects of salt stress and Fe deficiency in plants.

Combined transcriptome and metabolome analysis revealed pathways involved in improved salt tolerance of Gossypium hirsutum L. seedlings in response to exogenous melatonin application

BackgroundSalinization is major abiotic stress limiting cotton production. Melatonin (MT) has been implicated in salt stress tolerance in multiple crops including upland cotton. Here, we explored the transcriptomic and metabolomic response of a salt-tolerant self-bred high-yielding cotton line SDS-01, which was exogenously sprayed with four MT concentrations (50, 100, 200, and 500 μM).ResultsHere we found that MT improves plant biomass and growth under salt stress. The combined transcriptome sequencing and metabolome profiling approach revealed that photosynthetic efficiency is improved by increasing the expressions of chlorophyll metabolism and antenna proteins in MT-treated seedlings. Additionally, linoleic acid and flavonoid biosynthesis were improved after MT treatment. The Na+/K+ homeostasis-related genes were increasingly expressed in salt-stressed seedlings treated with MT as compared to the ones experiencing only salt stress. Melatonin treatment activated a cascade of plant-hormone signal transduction and reactive oxygen scavenging genes to alleviate the detrimental effects of salt stress. The global metabolome profile revealed an increased accumulation of flavonoids, organic acids, amino acids and derivatives, saccharides, and phenolic acids in MT-treated seedlings. Interestingly, N, N′-Diferuloylputrescine a known antioxidative compound was highly accumulated after MT treatment.ConclusionCollectively, our study concludes that MT is a salt stress regulator in upland cotton and alleviates salt-stress effects by modulating the expressions of photosynthesis (and related pathways), flavonoid, ROS scavenging, hormone signaling, linoleic acid metabolism, and ion homeostasis-related genes.

Nitrogen Availability Drives Mycorrhizal Effects on Wheat Growth, Nitrogen Uptake and Recovery under Salt Stress

The arbuscular mycorrhizal (AM) symbiosis is generally considered effective in improving salt tolerance in plants; however, the advantages it offers can vary greatly depending on the context in which it occurs; furthermore, the mechanisms underlying these responses are still unclear. A study was conducted to investigate the role of nitrogen (N) availability on the effectiveness of AM symbiosis in durum wheat (Triticum durum Desf.) plants grown under salt stress. Plants were grown in pots in the absence or in presence of salt stress (soil electrical conductivity of 1.50 and 13.00 dS m−1, respectively), with or without AM fungi inoculation (Rhizophagus irregularis and Funneliformis mosseae), varying the N dose supplied (0 or 80 mg N per pot). Results indicate that AM symbiosis can alleviate the detrimental effects of salt stress on the growth of durum wheat only when plants are grown under sufficient N availability in soil; in such conditions mycorrhizal symbiosis determined an improvement of leaf traits (leaf area, SLA, stability of plasma membranes and SPAD), N uptake, N fertilizer recovery and water use efficiency. On the contrary, when wheat plants were grown in conditions of N deficiency, the mycorrhizal symbiosis had no effect (under salt stress) or even depressive effect (under unstressed condition) on plant growth and N uptake, highlighting how, in some cases, competition for nutrients between plants and AM can arise. This study suggests that N availability in the soil can drive the effects of AM symbiosis in assisting the plant with containing saline stress.

Mycorrhizal Benefits of Salt-Stressed Cinnamomum camphora (L.) Presl. May Be Related to P and Mn2+ Contents in Shoots, Biomass Allocation, and K+/Na+ in Roots and Shoots

Arbuscular mycorrhizal fungi (AMF) are taken as bioameliorators to alleviate the detrimental effects of salt stress. However, how AMF affect the performance of Cinnamomum camphora, an economically important species, remains unclear. In this study, we evaluated the interactive effects of AMF and salinity on the growth, nutrient acquisition, and ion ratios of C. camphora. A factorial experiment was implemented in a greenhouse with four fungal regimes (inoculation with sterilized AMF, with Funneliformis mosseae or Rhizophagus irregularis, either alone or in combination), and three salt regimes (0, 50, and 200 mM NaCl). Results showed that salinity alone significantly reduced the total dry weight, mycorrhizal colonization, K+ concentration, and ionic homeostasis (particularly K+:Na+, Mg2+:Na+, and Ca2+:Na+) of whole plants. Mycorrhizal inoculation, particularly with R. irregularis, strongly mitigated some of the detrimental effects of salinity, enhancing the salt tolerance of C. camphora. Furthermore, the host plants benefited from the presence of AMF, mainly because they enhanced P and Mn2+ concentrations in the shoots, adjusted biomass allocation, and shifted the selective transporting capacity of K+ over Na+ from roots to shoots. Our results suggested that building mycorrhizal association between C. camphora and R. irregularis may be useful for plant cultivation in coastal areas.

CO2 enrichment changed N metabolism of tomatoes under salinity stress

• Elevated CO 2 reduced the negative effect of salinity stress in tomato. • Photosynthesis and transpiration improved in 50/50 v/v NO 3 : NH 4 but growth parameter was improved in 100/0 NO 3 : NH 4 in salinity stress in tomato. • The rate of reduction of vegetative traits due to salinity stress was significantly reduced by increasing the nitrate in the ratio of NO 3 : NH 4 in salinity stress in tomato. • Carbon dioxide enrichment was significant on protein and nitrate concentration. Salinity is a worldwide concern. The effects of CO 2 enrichment and N sources under salinity on the vegetative, photosynthetic, and biochemical parameters of tomato was explored. The tomato plants are cultivated in two climate-controlled greenhouses with two CO 2 levels: 300 (C1) and 700 (C2) ppm. Five NO 3 :NH 4 ratios (25/75(N1), 50/50(N2), 75/25(N3), and 100/0 (N4)) were used to fertilize plants in two salinity conditions (0 (S1) and 50 mM (S2)). When NH4 was raised, vegetative, yield and biochemical characteristics were seen to decline. By increasing nitrate, yield, and desirable tomato characteristics such as fresh weight of shoot, root, and fruit, dry weight of shoot and fruit, and the number of fruits per plant, photosynthesis, and water content of shoot were enhanced. Increased CO 2 mitigated the detrimental effects of salt stress. By increasing the nitrate in the ratio of NO 3 :NH 4 , notably in the S2N4 treatment, the rate of decrease of vegetative characteristics caused by salinity stress was greatly slowed. Under the detrimental influence of salinity stress, photosynthesis and transpiration improved in NO 3 :NH 4 , 50/50 (S2N2 treatment). In general, when the amount of ammonium was greater than nitrate (NO 3 :NH 4 ratio of 25/75) in both saline and non-saline conditions, the examined attributes did not demonstrate a favorable influence on all features.

Mitigating the detrimental effects of salt stress on anammox process: A comparison between glycine betaine and mannitol

The use of seawater to alleviate water shortages causes an increase of salinity in municipal pipe networks, posing challenges for biological wastewater treatment. The impacts of two compatible solutes on the anammox process under salt stress (20 g L−1) were compared here at the genetic and microbial levels. The findings revealed that both 0.3 mM glycine betaine (GB) and mannitol (MA) could alleviate the salt stress on anammox process, with GB exhibiting a better effect. Specifically, the addition of GB recovered the nitrogen removal efficiency (NRE) from 40 % to >80 % within 13 days. The addition of MA caused the reduction of the absolute abundance of hdh and hzsA, implying that 0.6 mM was not the optimal concentration. Moreover, salt stress induced an increase in the absolute abundance of nitrification functional genes and a decrease in the abundance of denitrification functional genes. Notably, compared with the initial level, the abundance of Candidatus Kuenenia increased by 7.1 % and 4.3 % after adding GB and MA, respectively. According to the network analysis, two compatible solutes promoted the bacterial interactions in anammox systems, which promoted the nitrogen circulation and further the nitrogen removal performance. This work provides a feasible strategy to relieve the salt stress on anammox process and then facilitates its application for treating saline wastewater.

A Highly Salt-Tolerant Bacterium Brevibacterium sediminis Promotes the Growth of Rice (Oryza sativa L.) Seedlings

Soil salinity has emerged as a serious issue for food security due to global climate change. It is estimated that currently about 62 million hectares or 20 percent of the world’s irrigated land is affected by salinity. Salinity is a serious problem in the coastal areas of Bangladesh. Isolation of salt-tolerant plant growth-promoting bacteria (PGPB) and applying them as bioinoculants in crop plants are considered promising and effective biotechnological approaches to combat soil salinity. This study aimed to screen salt-tolerant PGPB from the root, leaf, and rhizospheric soils of rice plants collected from salt-affected coastal areas including Chattogram, Noakhali, Lakshmipur, and Cox’s Bazar districts of Bangladesh and evaluated their performances on the seedling growth of rice. Out of forty-one salinity-tolerant bacterial isolates screened, Brevibacterium sediminis showed salinity tolerance up to 12% NaCl (w/v). In vitro bioassay revealed that B. sediminis promoted the seedling growth of rice cv. BRRI dhan29 (salinity susceptible) and BINAdhan-10 (salinity tolerant), and the growth-promoting effects were higher in BINAdhan-10. This study for the first time identified B. sediminis strain IBGE3C as a salt-tolerant PGPB from a widely cultivated rice variety, BRRI dhan28 in the Lakshmipur district of Bangladesh. Our results suggest that salt-tolerant PGPB isolated from the root, leaf, and rhizospheric soil of rice plants could be used as a low cost and environmentally friendly option for overcoming the detrimental effects of salt stress on rice plants in the southern coastal regions of Bangladesh. However, further studies are needed for assessing the efficacy of B. sediminis on enhancement of salinity tolerance, and growth and yield of rice under salinity stressed conditions.

Root Exposure to 5-Aminolevulinic Acid (ALA) Affects Leaf Element Accumulation, Isoprene Emission, Phytohormonal Balance, and Photosynthesis of Salt-Stressed Arundo donax.

Arundo donax has been recognized as a promising crop for biomass production on marginal lands due to its superior productivity and stress tolerance. However, salt stress negatively impacts A. donax growth and photosynthesis. In this study, we tested whether the tolerance of A. donax to salinity stress can be enhanced by the addition of 5-aminolevulinic acid (ALA), a known promoter of plant growth and abiotic stress tolerance. Our results indicated that root exposure to ALA increased the ALA levels in leaves along the A. donax plant profile. ALA enhanced Na+ accumulation in the roots of salt-stressed plants and, at the same time, lowered Na+ concentration in leaves, while a reduced callose amount was found in the root tissue. ALA also improved the photosynthetic performance of salt-stressed apical leaves by stimulating stomatal opening and preventing an increase in the ratio between abscisic acid (ABA) and indol-3-acetic acid (IAA), without affecting leaf methanol emission and plant growth. Supply of ALA to the roots reduced isoprene fluxes from leaves of non-stressed plants, while it sustained isoprene fluxes along the profile of salt-stressed A. donax. Thus, ALA likely interacted with the methylerythritol 4-phosphate (MEP) pathway and modulate the synthesis of either ABA or isoprene under stressful conditions. Overall, our study highlights the effectiveness of ALA supply through soil fertirrigation in preserving the young apical developing leaves from the detrimental effects of salt stress, thus helping of A. donax to cope with salinity and favoring the recovery of the whole plant once the stress is removed.

Alleviation of Salt Stress via Habitat-Adapted Symbiosis

Halotolerant plant-growth-promoting rhizobacteria (PGPR) could not only promote plant growth, but also help in counteracting the detrimental effects of salt stress. In the present study, a total of 76 bacteria were isolated from the rhizosphere, non-rhizospheric soil and endophytes of the halophyte Salsola tetrandra, collected from natural saline soils in Algeria. Phylogenetic analysis based on the 16S rDNA sequence of Gram-negative bacteria (n = 51) identified, showed seventeen representative isolates grouped into four genera (Pseudomonas, Acinetobacter, Enterobacter, and Providencia). These bacterial isolates that exhibited different PGPR traits were selected and tested for their ability to tolerate different abiotic stress (NaCl, PEG8000, and pH). The majority of isolates were drought tolerant (60% of PEG8000) and had an optimal growth at high pH values (pH 9 and 11) and some strains tolerated 2 M of NaCl. Strains identified as Enterobacter xiangfangensis BE1, Providencia rettgeri BR5 and Pseudomonas stutzeri MLR6 showed high capacity of adaptation on their PGP traits. The salt-tolerant isolates were finally chosen to promote growth and enhance salt tolerance, separately or combined, of Arabidopsis thaliana (Col-0) exposed or not to 0.1 M NaCl, by following fresh and root weight, primary root elongation and lateral root number. The best bacterial effect was recorded for the MLR6 strain in increasing shoot fresh weight and for BE1 in terms of root fresh weight in the absence of salt stress. At stressed conditions, all growth parameters declined. However, inoculation of Arabidopsis thaliana with the three bacterial strains (MLR6, BE1 and BR5), single or in co-culture, conferred an increase in the shoot weight, primary root length and lateral root number. The use of these strains separately or combined as biofertilizers seems to be a powerful tool in the development of sustainable agriculture in saline soils.

Comparative transcriptome and metabolome analysis reveal key regulatory defense networks and genes involved in enhanced salt tolerance of Actinidia (kiwifruit).

The Actinidia (kiwifruit) is an emerging fruit plant that is severely affected by salt stress in northern China. Plants have evolved several signaling network mechanisms to cope with the detrimental effects of salt stress. To date, no reported work is available on metabolic and molecular mechanisms involved in kiwifruit salt tolerance. Therefore, the present study aims to decipher intricate adaptive responses of two contrasting salt tolerance kiwifruit species Actinidia valvata [ZMH (an important genotype), hereafter referred to as R] and Actinidia deliciosa ['Hayward' (an important green-fleshed cultivar), hereafter referred to as H] under 0.4% (w/w) salt stress for time courses of 0, 12, 24, and 72hours (hereafter refered to as h) by combined transcriptome and metabolome analysis. Data revealed that kiwifruit displayed specific enrichment of differentially expressed genes (DEGs) under salt stress. Interestingly, roots of R plants showed a differential expression pattern for up-regulated genes. The KEGG pathway analysis revealed the enrichment of DEGs related to plant hormone signal transduction, glycine metabolism, serine and threonine metabolism, glutathione metabolism, and pyruvate metabolism in the roots of R under salt stress. The WGCNA resulted in the identification of five candidate genes related to glycine betaine (GB), pyruvate, total soluble sugars (TSS), and glutathione biosynthesis in kiwifruit. An integrated study of transcriptome and metabolome identified several genes encoding metabolites involved in pyruvate metabolism. Furthermore, several genes encoding transcription factors were mainly induced in R under salt stress. Functional validation results for overexpression of a candidate gene betaine aldehyde dehydrogenase (AvBADH, R_transcript_80484) from R showed significantly improved salt tolerance in Arabidopsis thaliana (hereafter referred to as At) and Actinidia chinensis ['Hongyang' (an important red-fleshed cultivar), hereafter referred to as Ac] transgenic plants than in WT plants. All in all, salt stress tolerance in kiwifruit roots is an intricate regulatory mechanism that consists of several genes encoding specific metabolites.

Influence of nitrogen on the growth and yield of cotton under salinity stress

Mineral nutrient supplementation is a vital strategy to detoxify the lethal effects of salinity stress induced by sodium chloride. To explore the role of mineral nutrition (nitrogen), a hydroponic experiment was carried out for the whole growing season to find out the effects of different levels of nitrogen (0.25, 2.5, and 5 mmol·L−1 N) on the growth and yield of upland cotton genotypes (salt-tolerant, ST, Z9807 and salt-sensitive, SS, Z0102) exposed to salt stress (200 mmol·L−1 NaCl). Salt stressed cotton genotypes exhibited a marked reduction in growth traits and dry biomass accumulation. Nitrogen confirmed its positive role by ameliorating the detrimental effects of salt stress on significant levels when supplied at 2.5 mmol·L−1 as compared to 5 mmol·L−1. Nitrogen application at 5 mmol·L−1 concentration suggestively increased all the morphological and physiological traits under the non-saline environment. Nitrogen at 2.5 mmol·L−1 progressively improved the root morphology of both tolerant and sensitive genotypes and ensured better nitrogen uptake under saline conditions. Besides, nitrogen supplementation at 2.5 mmol·L−1 proved beneficial in positively enhancing the photosynthetic pigment biosynthesis (3.05- and 4.14-fold for TChl, 1.72- and 2.06-fold for Car, and 2.84- and 2.96-fold for An for ST and SS), nitrogen content (9.26- and 11.19- fold for ST and SS), and the seed cotton yield (7.20 times in ST and 7.25 times in SS) of cotton genotypes as compared to the salinity treatment alone. Conclusively, the study results evidenced that nitrogen at moderate concentration can be advantageous in preventing NaCl induced damage.