NaCl-induced Salinity Stress Research Articles

Phlorotannins contribute to the ameliorative bioactivities of Ecklonia maxima-derived bioproduct in salt-stressed Solanumlycopersicum

Seaweed-derived bioproducts are increasingly being deployed as an environmentally friendly and sustainable approach to crop management under stressful growth conditions including salinity. The bioactivities of seaweed-derived extracts are linked to the presence of diverse groups of bioactive compounds. In the present study, the phlorotannins present in the seaweed Ecklonia maxima and Kelpak®, an E. maxima-derived bioproduct, were quantified and identified. Three phlorotannins were identified in E. maxima, namely eckol, 2-phloroeckol, and dibenzodioxin-fucodiphloroethol. Eckol (589.11 – 822.54 μg l−1) and dibenzodioxin-fucodiphloroethol (85 – 895 μg l−1) were present in Kelpak®. Phlorotannin bioactivity was investigated in tomato seedlings grown under NaCl-induced salinity stress. The seedlings treated with either individual phlorotannins (i.e., eckol or a fraction containing 2-phloroeckol and dibenzodioxin-fucodiphloroethol) or Kelpak® resulted in a reprogramming of biomass allocation as indicated by an increased root-to-shoot ratio. Phlorotannin and Kelpak® treatments induced the accumulation of antioxidants with an attendant augmentation of the antioxidant capacities and inhibition of membrane damage in the NaCl-stressed seedlings. Kelpak® treatment induced an increase in abscisic acid (ABA) accumulation and phlorotannin treatments lowered the ABA content of the stressed seedlings. These results demonstrated that phlorotannins contributed to the ameliorative actions of Kelpak®. The more potent effects of Kelpak®, in comparison to phlorotannins, in improving dry matter accumulation, ABA content, antioxidative properties, and inhibiting tissue injury of the salt-stressed tomato seedlings may be attributed to the presence of other bioactive components in the Kelpak® product.

Assessment of seedling emergence, growth traits and physiological indices of a medicinal plant Calotropis gigantea (L.) Aiton f. under NaCl induced salinity stress

Assessment of seedling emergence, growth traits and physiological indices of a medicinal plant Calotropis gigantea (L.) Aiton f. under NaCl induced salinity stress

Modulation of antioxidant defense and PSII components by exogenously applied acetate mitigates salinity stress in Avena sativa

Salinity stress has detrimental effects on various aspects of plant development. However, our understanding of strategies to mitigate these effects in crop plants remains limited. Recent research has shed light on the potential of sodium acetate as a mitigating component against salinity stress in several plant species. Here, we show the role of acetate sodium in counteracting the adverse effects on oat (Avena sativa) plants subjected to NaCl-induced salinity stress, including its impact on plant morphology, photosynthetic parameters, and gene expression related to photosynthesis and antioxidant capacity, ultimately leading to osmoprotection. The five-week experiment involved subjecting oat plants to four different conditions: water, salt (NaCl), sodium acetate, and a combination of salt and sodium acetate. The presence of NaCl significantly inhibited plant growth and root elongation, disrupted chlorophylls and carotenoids content, impaired chlorophyll fluorescence, and down-regulated genes associated with the plant antioxidant defense system. Furthermore, our findings reveal that when stressed plants were treated with sodium acetate, it partially reversed these adverse effects across all analyzed parameters. This reversal was particularly evident in the increased content of proline, thereby ensuring osmoprotection for oat plants, even under stressful conditions. These results provide compelling evidence regarding the positive impact of sodium acetate on various plant development parameters, with a particular focus on the enhancement of photosynthetic activity.

Effects of 5-Aminolevulinic Acid on Physiological and Biochemical Changes of In Vitro-Cultured Apple Plantlets Under NaCl-Induced Salinity Stress

Effects of 5-Aminolevulinic Acid on Physiological and Biochemical Changes of In Vitro-Cultured Apple Plantlets Under NaCl-Induced Salinity Stress

Effect of Salinity Stress on Oxidative Stress Parameters and the Activity of Antioxidant Enzymes in Eight Durum Wheat Genotypes

This study was carried out at the Tissue Culture Laboratory, which belongs to the General Commission of Biotechnology, in order to evaluate the influence of NaCl-induced salinity stress on some oxidative parameters (MDA and H2O2) and antioxidant enzymes (CAT, APX, and SOD) in eight durum wheat genotypes (Doma1, Bouhoth11, Cham3, Bezater, Cham5, Aghamatales, Icaverve, and Icamber) in vitro, to determine the most salinity tolerant genotypes. Salinity stress was applied by adding different levels of NaCl to the growing medium (0, 50, 100, and 150 mM). The experiment was laid according to a complete randomized design (CRD) with sixteen replicates. Increasing salinity level caused an increase in both the Hydrogen peroxide (H2O2), malondialdehyde (MDA) and the activity of the investigated antioxidant enzymes (SOD، APX، CAT) compared with the control. The leaf content of both H2O2 and MDA was significantly higher in the genotype Icaverve at the salinity level of 150 mM NaCl (45.67 and 130.74 µmol g-1 fresh wt. respectively), while the activity of the enzymes SOD, APX and CAT were significantly higher in the two durum wheat genotypes, Bouhoth11 and Doma1 at the highest salinity level (150 mM NaCl). Antioxidant enzymes play a pivotal role in the defense mechanisms in the durum wheat under salinity stress conditions, and the in vitro screening tool can be effectively used to assess the genetic variability for salinity tolerance in the durum wheat crop.

Evaluating the tolerance of chickpea ( Cicer arietinum L.) genotypes to salinity stressbased on a complex of morpho-physiological and yielding traits

Salinity is one of the most significant abiotic stress factors influencing crop production, especially in arid and semi-arid regions. Plants’ response to salinity stress depends on the cultivated genotype. A pot experiment was conducted to study the impact of two concentrations of sodium chloride (4 and 6 dS∙m–1) on some physiological and production traits of 58 chickpea genotypes. A genetic variation in the response of the investigated chickpea genotypes for NaCl-induced salinity stress was noted. Studied morphophysiological traits and yield components were affected under salt stress in all genotypes tested. Plant height was observed to have the lowest rate of reduction (32%, 48%) at 4 and 6 dS∙m –1, respectively. Leaf stomatal conductance decreased as salinity increased. Salinity stress conditions affected all studied yield components, but there was a genetic variation in the response of the studied genotypes. Under no stress conditions and compared to the other genotypes, the number of pods was significantly higher in BG362 genotype. The seed number was significantly higher in ILC9076 genotype. The 100 seed weight was significantly higher in the genotype ILC2664. The mean seed yield was significantly higher in ILC9354 and the harvest index was significantly higher in ILC8617. In general, salinity stress caused the reduction of all parameters. We assume that the assessment of tolerance of chickpea ( Cicer arietinum L.) genotypes to salinity stress should be based on a complex of morpho-physiological traits and analysis of yield complement.

Bacillus aryabhattai enhanced proline content, stabilized membrane and improved growth of cowpea under NaCl-induced salinity stress.

Salinity stress affects the growth of cowpea particularly at the stages of seed germination and early vegetative growth. This study examined the potential of particular stress-tolerant rhizospheric bacteria to improve the growth of cowpea under conditions of salinity stress. Two rhizobacillus genotypes, Bacillus filamentosus-C8 and Bacillus aryabhattai-C29 were evaluated for their potentials to protect cowpea under NaCl-induced salinity stress. At 200 mM of NaCl concentration, control (non-inoculated) cowpea was affected, C8 was not able to significantly (p ≤ 0.05) alleviate the effects of salinity stress on cowpea growth while C29 significantly (p ≤ 0.05) reduced leaf wilting, increased chlorophyll content and improved the growth of cowpea plant under stressed condition. Interestingly, C29 significantly (p ≤ 0.05) induced high proline content and stabilized membrane by loss of electrolytes. Our results indicate that stabilized membrane and enhanced proline content by Bacillus aryabhattai-C29 supported the growth of cowpea under salinity stress condition. This study revealed that rhizospheric bacteria screened for salinity stress tolerant have potential to be used as an effective bioprotectant for sustainable growth of cowpea under salinity stress condition.

Critical assessment of the filamentous green microalga Oedocladium carolinianum for astaxanthin and oil production

The filamentous microalga Oedocladium carolinianum that was isolated from soil was found to be capable of producing large amounts of astaxanthin under stress culture conditions. When the culture conditions were optimized, the maximum specific growth rate of 0.37 d−1 and the maximum biomass concentration of 10.12 g L−1 were obtained after 18 days of cultivation in 1-liter glass columns (inner diameter: 5 cm) under laboratory conditions. When subjected to culture conditions of nitrogen starvation and 2 g L−1 NaCl-induced salinity stress, however, the cells produced up to 3.91% w/w astaxanthin and a high astaxanthin productivity of 24.2 mg L−1 d−1 was obtained. Analysis by HPLC-MS revealed that the majority of astaxanthin was in fatty acid esterified forms with a typical molecular ratio of free, monoester and diester astaxanthin of 1:18:81. The biosynthesis of astaxanthin coincided with that of fatty acids, and the total fatty acid content reached 40% w/w or more. The technical feasibility of mass culture of O. carolinianum was tested in a 7000-L inclined thin-layer photobioreactor and a 10,000-L tubular photobioreactor in a greenhouse. This demonstrated that O. carolinianum grew rapidly in a nitrogen replete BG-11 culture medium and the maximum biomass concentrations obtained in the inclined thin-layer photobioreactor and tubular photobioreactor were 3.74 g L−1 and 3.07 g L−1 respectively, resulting in maximum biomass productivities of 276 mg L−1 d−1 and 198 mg L−1 d−1, respectively. Although small populations of a few zooplankton species occurred in the two types of photobioreactors, none grazed on O. carolinianum and they grazed on invading unicellular microalgae instead. It was therefore concluded that O. carolinianum is a promising microalga for sustainable co-production of astaxanthin and fatty acids.

Methyl jasmonate promotes salinity adaptation responses in two grapevine (Vitis vinifera L.) cultivars differing in salt tolerance

The effects of foliar spray of methyl jasmonate (MJ; 0, 50 and 100 µM) on phytochemical changes and nutritional balance of two grapevine (Vitis vinifera L.) cultivars [‘Sultana’ (as moderately salt-tolerant) and ‘Rishbaba’ (as a least salt-tolerant)] were evaluated under different saline conditions (NaCl; 0 and 75 mM). To explore optimum concentration of MJ treatment, grapevine plants were sprayed with MJ twice a day at 12-h intervals during the second week of salinity stress. The results showed that foliar spray of MJ especially at 100 µM was effective in alleviating deleterious effects of NaCl-induced salinity stress on both cultivars. The MJ at 50 and 100 µM significantly decreased ion leakage and production of malondialdehyde and hydrogen peroxide, but increased photosynthetic pigments, soluble carbohydrate, proline, and total phenol and flavonoid contents, especially in ‘Sultana’ compared with ‘Rishbaba’. Moreover, application of 100 µM MJ was associated with enhanced the activities of catalase, guaiacol peroxidase, and ascorbate peroxidase, resulting in greater leaf cell biomembranes stability in vines under saline condition compared with control plants (no treatment). The MJ was also associated with decreased accumulation of sodium and chlorine in leaves, but increased leaf minerals and trace elements compared with control vines. These findings suggest that foliar application of MJ, especially at 100 µM, might be useful to reduce negative effects of salinity stress in vineyards and nurseries.

Overexpression of cytoplasmic Solanum tuberosum Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene improves PSII efficiency and alleviates salinity stress in Arabidopsis.

ABSTRACT In this study, transgenic Arabidopsis lines expressing a potato gene (D43), encoding Glyceraldehyde 3-phosphate dehydrogenase, were studied. The D43 plants exhibited improved morphological parameters and accumulation of photosynthetic pigments compared to wild-type (WT) plants under salinity stress conditions. In addition, the D43 transgenic plants showed significantly reduced electrolyte leakage, higher stomatal conductance, lower malondialdehyde (MDA) content, and higher proline content than the WT plants under salinity stress. The gene expression analysis showed that the D43 plants accumulated 1.7-fold, 2.2-fold, and 1.3-fold higher mRNA transcripts of genes encoding the antioxidant enzymes ascorbate peroxidase (APX), superoxide dismutase (SOD), and catalase (CAT), respectively under salt-stress conditions. Furthermore, they significantly altered the expression of seven major stress-responsive genes, which indicated that overexpression of the potato D43 gene gave salinity stress resistance to Arabidopsis. Chlorophyll-a fluorescence kinetics confirmed the efficient photon absorption, electron transport, and overall PSII efficiency that led to improved photosynthesis in the D43 plants subjected to NaCl-induced salinity stress. Overall, our findings have suggested that potato D43 is a potential candidate gene for developing salinity stress resistance in higher plants.

Varietal differences in physiological and biochemical responses to salinity stress in six finger millet plants.

Finger millet is an important cereal that is grown in semi-arid and arid regions of East-Africa. Salinity stress is a major environmental impediment for the crop growth and production. This study aimed to understand the physiological and biochemical responses to salinity stress of six Kenyan finger millet varieties (GBK043137, GBK043128, GBK043124, GBK043122, GBK043094, GBK043050) grown across different agroecological zones under NaCl-induced salinity stress (100, 200 and 300mM NaCl). Seeds were germinated on the sterile soil and treated using various concentrations of NaCl for 2weeks. Early-seedling stage of germinated plants were irrigated with the same salt concentrations for 60days. The results indicated depression in germination percentage, shoot and root growth rate, leaf relative water content, chlorophyll content, leaf K+ concentration, and leaf K+/Na+ ratios with increased salt levels and the degree of increment differed among the varieties. On the contrary, the content of proline, malonaldehyde, leaf total proteins, and reduced sugar increased with increasing salinity. At the same time, the leaf Na+ and Cl- amounts of all plants increased substantially with increasing stress levels. Clustering analysis placed GBK043094 and GBK043137 together and these varieties were identified as salt-tolerant based on their performance. Taken together, our findings indicated a significant varietal variability for most of the parameters analysed. The superior varieties identified could be used as promising genetic resources in future breeding programmes directed towards development of salt-tolerant finger millet hybrids. Further analysis at genomic level needs to be undertaken to better understand the genetic factors that promote salinity tolerance in finger millet.

Effect of NaCl-Induced Salinity Stress on Growth, Osmolytes and Enzyme Activities in Wheat Genotypes.

Effect of NaCl-induced salinity stress was studied on three wheat (Triticum aestivum L.) genotypes (Platinum Lok 1, Eagle 135 and Kisan farmer). Seedling growth characteristics, chlorophyll contents, lipid peroxidation (MDA contents), proline, glycine betaine (GB) and the activities of catalase and peroxidase enzymes were evaluated at the seedling stage. The magnitude of reduction in growth parameters and chlorophyll contents was less in Platinum Lok 1 as compared to Kisan Farmer and Eagle 135. Platinum Lok 1 exhibited the highest increase in free proline and GB contents under NaCl stress as compared to the other two genotypes. Compared to Platinum Lok 1 and Eagle 135, Kisan Farmer accumulated more MDA contents under salinity stress. The enzyme activities were significantly higher in Platinum Lok 1 when compared to the other two genotypes. Therefore, these parameters could provide useful markers for the identification of salinity stress tolerant wheat genotypes at the seedling stage.

Screening of salt tolerant transgenic and non-transgenic cotton varieties under various levels of NaCl induced salinity stress

Screening of salt tolerant transgenic and non-transgenic cotton varieties under various levels of NaCl induced salinity stress

Physiological and growth responses of sour cherry (Prunus cerasus L.) plants subjected to short-term salinity stress

Abstract The gradual response of CAB-6P sour cherry (Prunus cerasus L.) plants to NaCl-induced salinity stress (60 mM NaCl) was investigated in a short-term hydroponic experiment, based on parameters relating to the growth, water relations, chlorophyll and mineral nutrition. The results showed that CAB-6P plants are very sensitive to salinity stress because their growth and leaf chlorophyll concentration were both affected negatively from the 3rd and 5th day, respectively, after incurring salinity stress. Since root growth was suppressed more severely than shoot growth, the shoot to root ratio was significantly increased under saline conditions. The concentrations of Na in leaves and stem of NaCl-treated plants were much lower than those measured in roots, suggesting Na exclusion mechanism from the shoot. The opposite trend was observed for Cl, indicating Cl inclusion mechanism to leaves. As regards the concentrations of Ca, Mg, P, K, Na, Fe, Zn and Mn, they were not changed in higher salinity conditions, apart from K, concentrations of which in leaves and roots were significantly increased and decreased, respectively (K translocation to leaves). Salinity further reduced K/Na ratio in root and stem as well as leaf water and osmotic potentials, whereas leaves of control and NaCl-treated plants presented similar turgor potential and K/Na ratio. These data add very important information to our knowledge about the physiological events occurring in sour cherry plants after even short-term exposure to salinity.

Effect of dynamic unequal distribution of salts in the root environment on performance and Crop Per Drop (CPD) of hydroponic-grown tomato

Due to water shortage, application of saline water for irrigation is an urgent requirement in agriculture. The aim of this study was to investigate the effects of NaCl-induced salinity stress on the growth and Crop Per Drop (CPD) of tomato ( Lycopersicon esculentum var. Falcato F1) in a dynamic split-root hydroponic system. Roots of tomato seedlings were separated into approximately two equal parts, half was grown in a box containing aerated nutrient solution (A-half), and the other half was grown in a similar box containing aerated saline water (B-half). Four salinity levels (0, 40, 80, and 120 mM NaCl) were applied at the B-half. At the static split-root hydroponic system, significant difference was found between the tomato roots supplied with the nutrient solution and those supplied with saline waters in the root volume and fresh and dry matter weight. By increasing NaCl concentration in the B-half, the root growth was decreased. At the dynamic split-root system, interchanging the split roots between the nutrient solution and the saline water at 3-day intervals resulted in significant reduction of tomato growth, fruit yield and CPD. The highest CPD was found at the treatment where in a 7-day dynamic split-root system, half of the roots were exposed to the nutrient solution and the other half was immersed in the 40 mM NaCl solution. At the 7-day intervals treatments, exposing the split root to 80 and 120 mM NaCl concentrations resulted in significant reduction of the plant growth, fruit yield and the CPD. The results showed that the dynamic split-root hydroponic system is an applicable technique for using saline waters; although the success of this system is strongly dependent on the salinity level and the exchange interval of root parts between the nutrient solution and saline water.

Solute accumulation and osmotic adjustment characteristics of the mangrove Avicennia marina under NaCl-induced salinity stress

Osmotic adjustment characteristics of mangrove leaves (Avicennia marina) were investigated over 45 days of growth under three NaCl concentrations (0, 200 and 600 mm NaCl). Maximum seedling growth occurred at 200 mm NaCl. Leaf water potential and osmotic potential were more negative under saltier conditions. The salinity treatments caused an increase in the leaf contents of Na+, Cl-, glycine betaine, total free amino acids and proline. However, inorganic ions (especially Na+ and Cl-) played a key role in osmotic adjustment in A. marina leaves, as they contributed 70% and 76% to these adjustments in 200 and 600 mm NaCl-treated plants, respectively. NaCl treatment induced a decrease in the organic solute contribution. Thus, growth of A. marina was stimulated by the 200 mm NaCl treatment due to effective osmotic adjustment, mainly by accumulation of inorganic ions. Reduction in growth when A. marina was subjected to high salinity stress (600 mm NaCl) appears to have been caused for the most part by the accumulation of excess NaCl (ionic effect), exacerbated by additional organic solute synthesis, rather than an osmotic effect.

Vegetative growth, superoxide dismutase activity and ion concentration of salt-stressed watermelon as influenced by rootstock

SUMMARYWatermelon is a crop with a high water demand and is frequently grown under conditions of higher than normal root-zone salinity. In the present study, seedlings of watermelon (cv. Fantasy, Citrullus lanatus (Thunb.) Matsum & Nakai) were grown either ungrafted or grafted on three rootstocks: Strong Tosa, S1 (both Cucurbita maxima×Cucurbita moschata), or Emphasis (Lagenaria siceraria). All the plants were exposed to an NaCl-induced salinity stress (electrical conductivity, EC=2·2, 4·0, or 6·0 dS/m). The vegetative growth of all the plants substantially reduced after 2 weeks of exposure to 6·0 dS/m; however, growth of the plants grafted on Strong Tosa reduced less than that of the others. The leaf water content and specific leaf area (SLA, m2/g) decreased with an increasing salinity in grafted plants, but not in ungrafted plants. Salinity induced an increase of superoxide dismutase (SOD) activity in grafted plants up to two-fold depending on the rootstock, whereas it had no effect on this enzyme activity in ungrafted plants. Leaf Na+ concentration increased with increasing salinity in ungrafted and S1 grafted plants, whereas there was no significant leaf Na+ accumulation in Emphasis and Strong Tosa grafted plants. Leaf K+ concentration was affected by the rootstock but not by salinity, thus, the ability to keep a high K+/Na+ ratio was achieved mainly by limiting leaf Na+ concentration. The rootstock determined the leaf Cl− accumulation, with lower overall concentrations found if plants were grafted on the S1 rootstock than on Emphasis or ungrafted plants. Salinity significantly decreased the leaf NO3− concentration on Emphasis grafted plants only, while the NO3−/Cl− ratio was reduced in all the rootstocks. The capacity of Strong Tosa to withstand salt stress better than other tested rootstocks was probably due to the ability to induce anatomical adaptation (SLA) and SOD activity in response to salt stress, and also to the efficiency of Na+ exclusion from the shoot.

Overexpressing SgNCED1 in Tobacco Increases ABA Level, Antioxidant Enzyme Activities, and Stress Tolerance

Abscisic acid (ABA) regulates plant adaptive responses to various environmental stresses. 9-cis-epoxycarotenoid dioxygenase (NCED) is the key enzyme of ABA biosynthesis in higher plants. A NCED gene, SgNCED1, was overexpressed in transgenic tobacco plants which resulted in 51–77% more accumulation of ABA in leaves. Transgenic tobacco plants decreased stomatal conductance, transpiration rate, and photosynthetic rate but induced activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate-peroxidase (APX). Hydrogen peroxide (H2O2) and nitric oxide (NO) in leaves were also induced in the transgenic plants. Compared to the wild-type control, the transgenic plants improved growth under 0.1 M mannitol-induced drought stress and 0.1 M NaCl-induced salinity stress. It is suggested that the ABA-induced H2O2 and NO generation upregulates the stomatal closure and antioxidant enzymes, and therefore increases drought and salinity tolerance in the transgenic plants.