Salt Tolerance In Wheat Research Articles

Effect of brackish water irrigation on soil degradation and performance of salt tolerant wheat and maize genotypes

A field experiment was conducted to study the effect of brackish water on soil physical and chemical conditions and yield of wheat and maize genotypes at the farmers’ field. Two salt tolerant genotypes for each crop were selected from previous hydroponic and lysimeters studies. Wheat-maize cropping system was followed using tubewell brackish water alone and with chemical (gypsum) and organic (FYM) amendments. The results revealed that treatments have significant effect on all growth and yield parameters and followed the trend of T1>T3 >T4 > T2. Highest grain yield of wheat genotypes (SARC-1 & V-8670) was observed in control (4050 & 3800 kg/ha) and lowest was in T2 (2862 & 2200 kg/ha). Similar trend was observed in maize fodder yield that was 9625 & 8875 kg/ha in control and 4350 & 2253 kg/ha in T2 for Sahiwal-02 and Akbar, respectively. Maximum reduction in wheat grain and maize fodder yield observed in T2 (tubewell water alone) where high EC, SAR and RSC water was applied that was 39 & 57% for 1st year (wheat crop) and 89 & 74% for 2nd year (maize crop) respectively. Data revealed that use of gypsum and FYM along with brackish water improved the wheat grain yield and maize fodder as compared to T2. More adverse effect of brackish water was observed in high EC, SAR and RSC treatment (tubewell water alone) as compared to other treatments. Application of amendments (gypsum and FYM) along with brackish tubewell water reduced adverse effect of brackish water. Among genotypes SARC-1 and Sahiwal-2002 performed better in all treatments and textures especially under brackish water treatments.Bangladesh J. Agril. Res. 42(4): 693-705, December 2017

The defensive role of silicon in wheat against stress conditions induced by drought, salinity or cadmium

In the crust of earth, silicon (Si) is one of the two major elements. For plant growth and development, importance of Si remains controversial due to the widely differences in ability of plants to take up this element. In this paper, pot experiments were done to study Si roles in improving salt, drought or cadmium (Cd) stress tolerance in wheat. Up to full emergence, all pots were watered at 100% field capacity (FC) every other day with nutrient solution without any treatments. Fifteen days after sowing, pots were divided into four plots, each with 40 pots for no stress (control) and three stress treatments; drought (50% FC), salinity (200 mM NaCl) and cadmium (2 mM Cd). For all plots, Si was applied at four levels (0, 2, 4 and 6 mM). Under no stress condition, Si applications increased Si content and improved growth as a result of reduced electrolyte leakage (EL), malondialdehyde (MDA) and Na+ contents. Under stress conditions, Si supplementation conferred higher growth, gas exchange, tissue water and membranes stabilities, and K+ content, and had limited MDA and Na+ contents and EL compared to those obtained without Si. Compared to those without Si, enzyme (e.g., superoxide dismutase, catalase and peroxidase) activity was improved by Si applications, which were linked with elevated antioxidants and osmoprotectants (e.g., free proline, soluble sugars, ascorbic acid and glutathione) contents, might providing antioxidant defense against abiotic stress in wheat. The level of 4 mM Si was most effective for mitigating the salt and drought stress conditions, while 6 mM Si level was most influentially for alleviating the Cd stress condition. These results suggest that Si is beneficial in remarkably affecting physiological phenomena and improving wheat growth under abiotic stress.

Effect of salinity and drought stress on germination and early seedlings growth of bread wheat (Triticum aestivum L.)

Salinity is one of the most important environmental stresses that limits soil fertility and has adverse effects on plant growth. In order to increase wheat production under saline conditions, it is necessary to better understand genotypic difference, the physiological and biochemical processes of salt tolerance in wheat. The aim of this study was to determine the most tolerant winter wheat varieties against salinity and osmotic stress at germination stage and early seedlings growth. The salinity and osmotic stress were simulated in controlled environmental conditions by adding different concentrations of NaCl and mannitol solution to the growing media of five winter wheat variety. In all studied varieties the benchmark water potential in which they had germinated and had a good seedlings growth was of -0.3MPa. Under the stronger stress, -0.6 MPa, all varieties showed reduction in the all examined parameters. The variety Bosanka, had the highest final germination and germination energy under both mannitol and salt stress treatments. The parameters defining the development or percentage of strong seeds, coleoptile and root length, fresh and dry weight of root and coleoptile of a seed were more affected by water deficit stress and salt stress than germination and germination energy. Biplot analysis showed that wheat cultivars grown under -0.6MPa osmotic had higher values of root/coleoptile ratio in relation to control and -0.3MPa treatment which is the most reliable for screening properties of the genotypes for drought resistance in seedling stage.

Cloning and Regulation Function Analysis of TaSC Promoter from Salt Tolerant Wheat

Cloning and Regulation Function Analysis of <i>TaSC</i> Promoter from Salt Tolerant Wheat

THE ROLE OF PLANT-MICROBE SYMBIOSESIN INCREASING STRESS TOLERANCE OF CEREAL CROPS IN THE CIS-URAL REGION

Rhizosphere and epiphytic bacteria isolated from the saline soils of the Perm region and also from the surface of cereal crops seedlings are able to form associations with agricultural crops. It is established that the activation of the mechanisms of cold resistance of winter rye, wheat, triticale and salt tolerance of spring wheat by increasing of carotenoid concentration is regulated by associative bacteria. Application of mineral presowing treatment of winter crops leads to qualitative changes in associative bacteria composition and also reduces photosynthetic potential of wheat and triticale after herbicides treatment. Associative methylobacteria under salt stress have major impact on host plant antioxidant system activation (synthesis of carotenoids) than nitrogen-fixing bacteria. Epiphytic halotolerant nitrogen-fixing, nitrate-reducing and denitrifying bacteria of spring cereals (wheat, oat, rye) exhibiting phosphate solubilizing activity under salt stress in the soil.

Performance of Salt Tolerant Wheat Varieties in Salt Affected Soils

Performance of Salt Tolerant Wheat Varieties in Salt Affected Soils

Structural variations in wheat HKT1;5 underpin differences in Na+ transport capacity.

An important trait associated with the salt tolerance of wheat is the exclusion of sodium ions (Na+) from the shoot. We have previously shown that the sodium transporters TmHKT1;5-A and TaHKT1;5-D, from Triticum monoccocum (Tm) and Triticum aestivum (Ta), are encoded by genes underlying the major shoot Na+-exclusion loci Nax1 and Kna1, respectively. Here, using heterologous expression, we show that the affinity (K m) for the Na+ transport of TmHKT1;5-A, at 2.66mM, is higher than that of TaHKT1;5-D at 7.50mM. Through 3D structural modelling, we identify residuesD471/a gap and D474/G473 that contribute to this property. We identify four additional mutations in amino acid residues that inhibit the transport activity of TmHKT1;5-A, which are predicted to be the result of an occlusion of the pore. We propose that the underlying transport properties of TmHKT1;5-A and TaHKT1;5-D contribute to their unique ability to improve Na+ exclusion in wheat that leads to an improved salinity tolerance in the field.

Comprehensive evaluating of wild and cultivated emmer wheat (Triticum turgidum L.) genotypes response to salt stress

Emmer wheat as the progenitor of common wheat, holds the genetic potentiality for improvement of wheat yield, quality and stress tolerance such as drought and salt. To comprehensively evaluate the salt tolerance of emmer wheat, a total of 30 traits including growth, physiology and photosynthesis related as well as K+ and Na+ content of 30 wild emmer and 14 durum wheat accessions were systematically investigated and compared between normal and saline conditions. Salt tolerance index (STI) based on multiple regression analysis of these traits was calculated and five wild emmer accessions showed high salt tolerance, which could be used as valuable resource for wheat salt tolerance improvement. Furthermore, wild emmer genotypes showed wider trait performance variation compared to durum wheat, indicating the higher genetic diversity in wild emmer wheat. Then, shoot Na+ content, shoot K+/Na+ ratio, root length and root surface area were identified as suitable indexes for salt tolerance evaluation. Na+ exclusion mechanism was found to be playing an important role in response to salt stress in emmer wheat. The salt tolerance in emmer wheat was systematically characterized here, which not only provided the elite germplasm for wheat improvement, but also provided the efficient method and some useful indexes for salt tolerance assessing.

Plant growth-promoting rhizobacteria enhance wheat salt and drought stress tolerance by altering endogenous phytohormone levels and TaCTR1/TaDREB2 expression.

Abiotic stresses such as salt and drought represent adverse environmental conditions that significantly damage plant growth and agricultural productivity. In this study, the mechanism of the plant growth-promoting rhizo-bacteria (PGPR)-stimulated tolerance against abiotic stresses has been explored. Results suggest that PGPR strains, Arthrobacter protophormiae (SA3) and Dietzia natronolimnaea (STR1), can facilitate salt stress tolerance in wheat crop, while Bacillus subtilis (LDR2) can provide tolerance against drought stress in wheat. These PGPR strains enhance photosynthetic efficiency under salt and drought stress conditions. Moreover, all three PGPR strains increase indole-3-acetic acid (IAA) content of wheat under salt and drought stress conditions. The SA3 and LDR2 inoculations counteracted the increase of abscisic acid (ABA) and 1-aminocyclopropane-1-carboxylate (ACC) under both salt and drought stress conditions, whereas STR1 had no significant impact on the ABA and ACC content. The impact of PGPR inoculations on these physiological parameters were further confirmed by gene expression analysis as we observed enhanced levels of the TaCTR1 gene in SA3-, STR1- and LDR2-treated wheat seedlings as compared to uninoculated drought and salt stressed plants. PGPR inoculations enhanced expression of TaDREB2 gene encoding for a transcription factor, which has been shown to be important for improving the tolerance of plants to abiotic stress conditions. Our study suggest that PGPR confer abiotic stress tolerance in wheat by enhancing IAA content, reducing ABA/ACC content, modulating expression of a regulatory component (CTR1) of ethylene signaling pathway and DREB2 transcription factor.

Inducing salt tolerance in wheat through inoculation with rhizobacteria containing 1-aminocyclopropane-1-carboxylate deaminase activity

Wheat (Triticum aestivum) is the fundamental feed of people as it contributes 60% of the daily diet of ordinary man in Pakistan. Salinity is one of the most imperative stresses that hinder agricultural productivity in nearly every part of the world. Improved biosynthesis of ethylene in plants under salinity stress is well established. Higher ethylene concentration retards root growth and eventually disturbs the overall plant growth. Plant growth promoting Rhizobacteria (PGPR) emits 1-aminocyclopropane-1-carboxylate (ACC) deaminase action under salt stressed conditions which minimizes the power of ACC and ethylene justifying the lethal effects of salt stress on plant growth. The seeds inoculated with PGPR having ACC deaminase are comparatively more tolerant to salt stress. The study was conducted at National Agriculture Research Centre Islamabad to examine the influence of PGPR on wheat growth (cultivars Pak-13 NARC-11 and NARC-09) and ionic concentration under saline environment to see the impact of bacterial strains having ACC deaminase on wheat growth and ionic concentration. The experiment was set up following completely randomized design with three repeats. Wheat seeds were inoculated following rhizobacteria strains, WPR-61, WPR-51, WPS-09 and Consortium of WPR-61, WPR-51 and WPS-09. Salinity (10.62dS m-1) was artificially developed using salts. Shoot and root length significantly affected by different rhizobial strains. The maximum root and shoot length attained by the consortium of three strains. The best results were achieved on NARC-09 wheat variety.Pak-13 wheat variety was significant affected by different rhizobial strains and maximum phosphorus concentration attained by WPS-09 strain in Pak-13.

Seed priming by sodium nitroprusside improves salt tolerance in wheat (Triticum aestivum L.) by enhancing physiological and biochemical parameters

The germination, seedling vigor, crop establishment and yield of agronomically important crops is negatively affected by soil salinity. The current study aimed to investigate the ability of exogenous fertigation by sodium nitroprusside (SNP) to induce salt tolerance in four high yielding wheat cultivars (Sahar-06, Punjab-11, Millat-11 and Galaxy-13) that differ in their response to salt stress in terms of biomass production, oxidative defense mechanisms and grain yield. Three levels of SNP (0, 0.1 and 0.2 mM) were used for seed soaking. During soaking the seeds were kept in the dark. After soaking for 12 h the seeds were air-dried for 5 h before sowing. Salinity caused a significant reduction in biomass and grain yield, while it increased proline (Pro), ascorbic acid (AsA), hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents. Cultivar Sahar-06 and Galaxy-13 were found more tolerant to salinity based on shoot length root fresh and dry wights, 100 grain weight, decreased MDA and H2O2 accumulation, phenolic and ascorbic acid (AsA) contents, accumulation of proline, activities of SOD, POD and CAT as compared to the other cultivars. Seed priming with SNP was effective in reducing the adverse effects of salt stress induced oxidative stress on plant biomass and grain yield in all the studied wheat cultivars, but maximum amelioration of salt stress tolerance by SNP treatment was found in cv. Sahar-06. The increased salt tolerance in wheat plants by SNP seed priming might be due to the role of NO in improving seed vigor and germination and early establishment of seedlings with better growth. 0.1 mM SNP was found the most effective in improving salt tolerance, as compared to other SNP concentations. Exogenous SNP fertigation increased the activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) and the contents of AsA, Pro and total phenolics content (TPC) in the salt stressed wheat plants. Our data indicate that SNP-priming induced salt tolerance by up-regulating the antioxidative defense mechanisms resulting in better biomass production and grain yield.

Seed priming and transgenerational drought memory improves tolerance against salt stress in bread wheat

This study was conducted to evaluate the potential of seed priming following terminal drought on tolerance against salt stress in bread wheat. Drought was imposed in field sown wheat at reproductive stage (BBCH growth stage 49) and was maintained till physiological maturity (BBCH growth stage 83). Seeds of bread wheat, collected from crop raised under terminal drought and/or well-watered conditions, were subjected to hydropriming and osmopriming (with 1.5% CaCl2) and were sown in soil-filled pots. After stand establishment, salt stress treatments viz. 10 mM NaCl (control) and 100 mM NaCl were imposed. Seed from terminal drought stressed source had less fat (5%), and more fibers (11%), proteins (22%) and total soluble phenolics (514%) than well-watered seed source. Salt stress reduced the plant growth, perturbed water relations and decreased yield. However, an increase in osmolytes accumulation (4–18%), malondialdehyde (MDA) (27–35%) and tissue Na+ contents (149–332%) was observed under salt stress. The seeds collected from drought stressed crop had better tolerance against salt stress as indicated by better yield (28%), improved water relations (3–18%), osmolytes accumulation (21–33%), and less MDA (8%) and Na contents (35%) than progeny of well-watered crop. Seed priming, osmopriming in particular, further improved the tolerance against salt stress through improvement in leaf area, water relations, leaf proline, glycine betaine and grain yield while lowering MDA and Na+ contents. In conclusion, changed seed composition during terminal drought and seed priming improved the salt tolerance in wheat by modulating the water relations, osmolytes accumulation and lipid peroxidation.

Screening of Salt Tolerance Capability of Wheat Genotypes under Salt Stress Condition

To screen salt tolerance wheat genotypes, germination and seedling growth characters were used as screening criteria. 33 wheat genotypes were tested under 5 different salt concentrations (0, 5, 10, 15 and 20 dSm-1) at central laboratory, Sher-e-bangla Agricultural University, Dhaka-1207, during February to March, 2016. The experiment was conducted with a complete randomize design (CRD) with 5 replications. The results of the experiment revealed that, various germination and seedling growth parameters of the wheat genotypes varied significantly under salt stress. A marked reduction of germination rate, shoot and root length, shoot and root dry weight, relative water content, water retention capacity and vigor index was observed with the increasing of salt concentration for most of the wheat genotypes except ESWYT-5, ESWYT-6 and BARI GOM 28. ESWYT-5, ESWYT-6 and BARI GOM 28 showed consistently better performance against salt stress and there were slow linear reduction was observed with the increasing of salt concentration from 0 to 20 dSm-1. So considering the above fact, ESWYT-5, ESWYT-6 and BARI GOM 28 could be promising salt stress genotype against moderate saline condition.

Improvement of Salt Tolerance in Durum Wheat (Triticum Durum Desf.) by Auxin and Kenitin Application

The aim of this work is to study the effect of soil salinity using different levels of NaCl (0, 10, 15 g/ NaCl) on some morphological and physiological properties of durum wheat (Triticum durum Desf.) var KEBIR in the vegetative stage. The results obtained allowed us to observe the negative impact of saline stress on the leaf area, Chlorophyll b, and carotenoids at moderate and higher salinity levels. The effect of salt on chlorophyll a content remains insignificant. On the other hand, proline content was highly affected by salt stress. It was excessively increased with the rise of osmotic stress levels, especially at higher salinity levels (15g/l NaCl). Phytohormones, such as auxin and cytokinin, are known to be involved in the regulation of plant responses to salinity stress. Also, it counteracts the adverse effect of stress conditions. Exogenous spraying of indole-3-acetic acid (IAA) and kinetin (K) with three various levels (10, 20, 30 p.p.m.), during the vegetative phase, indicated that an increase in the leaf area and pigments content are associated with a decrease in the proline content.

Comparative Performance of Multivariable Agro-Physiological Parameters for Detecting Salt Tolerance of Wheat Cultivars under Simulated Saline Field Growing Conditions.

Field-based trials are crucial for successfully achieving the goals of plant breeding programs aiming to screen and improve the salt tolerance of crop genotypes. In this study, simulated saline field growing conditions were designed using the subsurface water retention technique (SWRT) and three saline irrigation levels (control, 60, and 120 mM NaCl) to accurately appraise the suitability of a set of agro-physiological parameters including shoot biomass, grain yield, leaf water relations, gas exchange, chlorophyll fluorescence, and ion accumulation as screening criteria to establish the salt tolerance of the salt-tolerant (Sakha 93) and salt-sensitive (Sakha 61) wheat cultivars. Shoot dry weight and grain yield per hectare were substantially reduced by salinity, but the reduction was more pronounced in Sakha 61 than in Sakha 93. Increasing salinity stress caused a significant decrease in the net photosynthesis rate and stomatal conductance of both cultivars, although their leaf turgor pressure increased. The accumulation of toxic ions (Na+ and Cl-) was higher in Sakha 61, but the accumulation of essential cations (K+ and Ca2+) was higher in Sakha 93, which could be the reason for the observed maintenance of the higher leaf turgor of both cultivars in the salt treatments. The maximum quantum PSII photochemical efficiency (Fv/Fm) and the PSII quantum yield (ΦPSII) decreased with increasing salinity levels in Sakha 61, but they only started to decline at the moderate salinity condition in Sakha 93. The principle component analysis successfully identified the interrelationships between all parameters. The parameters of leaf water relations and toxic ion concentrations were significantly related to each other and could identify Sakha 61 at mild and moderate salinity levels, and, to a lesser extent, Sakha 93 at the moderate salinity level. Both cultivars under the control treatment and Sakha 93 at the mild salinity level were identified by most of the other parameters. The variability in the angle between the vectors of parameters explained which parameters could be used as individual, interchangeable, or supplementary screening criteria for evaluating wheat salt tolerance under simulated field conditions.

Interactive effect of salinity and silver nanoparticles on photosynthetic and biochemical parameters of wheat

ABSTRACTThe present study investigated the influence of seed priming with silver nanoparticles (Ag NPs), 0, 2, 5 and 10 mM, on growth and biochemical parameters of wheat (Triticum aestivum L.) under salt stress. As expected, 150 mM of NaCl decreased the shoot fresh and dry weights and chlorophyll contents and increased the catalase (CAT) and peroxidase (POD) activities. Salinity enhanced the concentration of proline, soluble sugars, malondialdehyde and hydrogen peroxide. Seed priming with Ag NPs increased the shoot fresh and dry weight of normal and salt-stressed plants. Lower concentration of Ag NPs decreased the total soluble sugars and proline contents, while the higher Ag NPs levels increased these contents compared to the control. The combined application of Ag NPs and salt stress increased the soluble sugars and proline contents, while it decreased CAT activity and increased POD activity compared to the respective Ag NPs treatments alone. Overall, our results demonstrated that Ag NPs enhanced the salt tolerance in wheat, but the long-term response of Ag NPs under salt stress needs further investigation.

Methylglyoxal as a novel signal molecule induces the salt tolerance of wheat by regulating the glyoxalase system, the antioxidant system, and osmolytes.

Reactive carbonyl species methylglyoxal (MG) has always been regarded as a cytotoxic metabolite, but now is emerging to function as signal molecule in plants. However, whether MG can induce salt tolerance is elusive. In this study, treatment of wheat seeds with NaCl reduced seed germination, plant height, root length, fresh weight, and dry weight, indicating the inhibitive effects of NaCl on seed germination and seedling growth. The inhibitive effects of NaCl were alleviated by applying exogenous MG, but aggravated by the MG scavenger N-acetyl-L-cysteine (NAC), suggesting that MG could induce the salt tolerance of wheat. In addition, MG increased glyoxalase I and glyoxalase II activities and decreased endogenous MG content in wheat seedlings under NaCl stress, whereas coapplication of NAC weakened glyoxalase activity and enhanced the endogenous MG level. Also, MG activated superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase activities; increased glutathione and ascorbic acid levels; and decreased superoxide radical production and H2O2 and malondialdehyde contents under NaCl stress, while NAC reversed these physiological parameters. Furthermore, MG also induced the accumulation of proline, glycine betaine, and soluble sugar under NaCl stress, whereas this accumulation was weakened by NAC. This work reported for the first time that MG could induce the salt tolerance of wheat, and the acquisition of this salt tolerance was involved in the activation of the glyoxalase system and antioxidant system, as well as the accumulation of osmolytes.

Allelic variations and differential expressions detected at quantitative trait loci for salt stress tolerance in wheat

The increasing salinization of agricultural lands is a threat to global wheat production. Understanding of the mechanistic basis of salt tolerance (ST) is essential for developing breeding and selection strategies that would allow for increased wheat production under saline conditions to meet the increasing global demand. We used a set that consists of 150 internationally derived winter and facultative wheat cultivars genotyped with a 90K SNP chip and phenotyped for ST across three growth stages and for ionic (leaf K+ and Na+ contents) traits to dissect the genetic architecture regulating ST in wheat. Genome-wide association mapping revealed 187 Single Nucleotide Polymorphism (SNPs) (R2 = 3.00-30.67%), representing 37 quantitative trait loci (QTL), significantly associated with the ST traits. Of these, four QTL on 1BS, 2AL, 2BS and 3AL were associated with ST across the three growth stages and with the ionic traits. Novel QTL were also detected on 1BS and 1DL. Candidate genes linked to these polymorphisms were uncovered, and expression analyses were performed and validated on them under saline and non-saline conditions using transcriptomics and qRT-PCR data. Expressed sequence comparisons in contrasting ST wheat genotypes identified several non-synonymous/missense mutation sites that are contributory to the ST trait variations, indicating the biological relevance of these polymorphisms that can be exploited in breeding for ST in wheat.

Comparative Analysis of WRKY Genes Potentially Involved in Salt Stress Responses in Triticum turgidum L. ssp. durum.

WRKY transcription factors are involved in multiple aspects of plant growth, development and responses to biotic stresses. Although they have been found to play roles in regulating plant responses to environmental stresses, these roles still need to be explored, especially those pertaining to crops. Durum wheat is the second most widely produced cereal in the world. Complex, large and unsequenced genomes, in addition to a lack of genomic resources, hinder the molecular characterization of tolerance mechanisms. This paper describes the isolation and characterization of five TdWRKY genes from durum wheat (Triticum turgidum L. ssp. durum). A PCR-based screening of a T. turgidum BAC genomic library using primers within the conserved region of WRKY genes resulted in the isolation of five BAC clones. Following sequencing fully the five BACs, fine annotation through Triannot pipeline revealed 74.6% of the entire sequences as transposable elements and a 3.2% gene content with genes organized as islands within oceans of TEs. Each BAC clone harbored a TdWRKY gene. The study showed a very extensive conservation of genomic structure between TdWRKYs and their orthologs from Brachypodium, barley, and T. aestivum. The structural features of TdWRKY proteins suggested that they are novel members of the WRKY family in durum wheat. TdWRKY1/2/4, TdWRKY3, and TdWRKY5 belong to the group Ia, IIa, and IIc, respectively. Enrichment of cis-regulatory elements related to stress responses in the promoters of some TdWRKY genes indicated their potential roles in mediating plant responses to a wide variety of environmental stresses. TdWRKY genes displayed different expression patterns in response to salt stress that distinguishes two durum wheat genotypes with contrasting salt stress tolerance phenotypes. TdWRKY genes tended to react earlier with a down-regulation in sensitive genotype leaves and with an up-regulation in tolerant genotype leaves. The TdWRKY transcripts levels in roots increased in tolerant genotype compared to sensitive genotype. The present results indicate that these genes might play some functional role in the salt tolerance in durum wheat.

Exogenously applied poly-γ-glutamic acid alleviates salt stress in wheat seedlings by modulating ion balance and the antioxidant system.

Salt stress is a main abiotic stress that limits agricultural productivity in many parts of the world. To investigate whether poly-γ-glutamic acid (γ-PGA) can alleviate the negative effects of salt stress on wheat, a foliar application of 400mg/L γ-PGA was applied to wheat seedlings, which were then subjected to 150mM NaCl. Our results showed that after application of γ-PGA, the plant height, the plant weight, and the antioxidant enzymes including superoxide dismutase, peroxidase, and catalase were significantly increased compared with the treatment of 150mM NaCl alone. Meanwhile, γ-PGA application also resulted in high accumulation of K+ and decreased storage of Na+ in wheat leaves. These results suggest that γ-PGA treatment may improve salt tolerance of wheat by diminishing ionic imbalances and enhancing antioxidant capacity. Our results indicate that exogenous γ-PGA could alleviate the damage caused by salt stress.