Salinity-stressed Plants Research Articles

Biochemical, photosynthetic and metabolomics insights of single and combined effects of salinity, heat, cold and drought in Arabidopsis.

Ensuring food security is one of the main challenges related to a growing global population under climate change conditions. The increasing soil salinity levels, drought, heatwaves, and late chilling severely threaten crops and often co-occur in field conditions. This work aims to provide deeper insight into the impact of single vs. combined abiotic stresses at the growth, biochemical and photosynthetic levels in Arabidopsis thaliana (L.). Reduced QY max was recorded in salinity-stressed plants, NPQ increased in heat and salinity single and combined stresses, and qP decreased in combined stresses. MDA and H2O2 content were consistently altered under all stress conditions, but higher values were recorded under salinity alone and in combination. Salinity alone and in stress combinations (especially with cold) provided a stronger hierarchical effect. Despite glycine and GABA osmolytes not significantly changing, proline highlighted the hierarchically stronger impact of salinity, while glycine-betaine was decreased under drought combinations. Untargeted metabolomics pointed out distinct metabolic reprogramming triggered by the different stress conditions, alone or in combination. Pathway analysis revealed that abiotic stresses significantly affected hormones, amino acids and derivates, and secondary metabolites. Flavonoids accumulated under drought (alone and combined with heat and cold stresses), while N-containing compounds decreased under all combined stresses. Looking at the interactions across the parameters investigated, antagonistic, additive, or synergistic effects could be observed depending on the biochemical process considered. Notwithstanding, these results contribute to delving into the impact of various stress combinations, hierarchically highlighting the stress-specific effects and pointing out different combinations.

Efficacy of two different microbial consortia on salinity tolerance in chickpea: an in-planta evaluation on biochemical, histochemical, and genomic aspects.

This study aimed to identify and characterize actinobacteria and rhizobia with plant growth-promoting (PGP) traits from chickpea plants. Out of 275 isolated bacteria, 25 actinobacteria and 5 chickpea rhizobia showed 1-aminocyclopropane-1-carboxylate deaminase (ACCd) activity. Selected chickpea rhizobia were tested for their nodulating capacity under sterile and non-sterile soil conditions. Further screening on salinity and PGP traits identified three promising isolates: Nocardiopsis alba KG13, Sinorhizobium meliloti KGCR17, and Bacillus safensis KGCR11. These three isolates were analyzed for their compatibility and made into a consortium (Consortium 1). This along with another consortium made from our salinity-tolerant lab strains Chryseobacterium indologenes ICKM4 and Stenotrophomonas maltophilia ICKM15 (Consortium 2) was compared in planta studies. Trials revealed that Consortium 2 showed significant (p < 0.05) tolerance and on above-ground, below-ground traits and yield components than Consortium 1. Moreover, both consortia induced nodulation in saline-stressed plants, alleviated electrolyte leakage (2.3 vs. 0.4 in ICCV 2; 1.8 vs. 0.6 in JG 11), and increased chlorophyll content. Histochemical staining indicated reduced oxidative stress and lipid peroxidation in consortium-treated plants under salinity stress. Further, gene expression studies revealed mixed patterns, with up-regulation of antioxidant and transporter genes observed in consortium-treated plants, particularly in Consortium 2. Overall, Consortium 2 showed better gene expression levels for antioxidant and transporter genes, indicating its superior efficacy in mitigating salinity stress in chickpea plants. This study provides valuable insights into the potential use of these microbial isolates in improving chickpea productivity by enhancing salinity tolerance.

Role of organic amendments in improving the morphophysiology and soil quality of Setaria italica under salinity

Salinity negatively impacts soil fertility by impairing the development and physiological functions of foxtail millet plants. Organic amendments have emerged as a viable solution in the reclamation and management of salinity inflicted soils and improve the performance of crop. In this regard, a pot experiment was carried out to examine the effect of organic amendments (OAs) on soil quality and its influence on the growth and physiology of foxtail millet under saline and non-saline condition. The findings indicated that under salt stress conditions, the levels of proline, hydrogen peroxide (H2O2), and electrolyte leakage (EL) risen, whilst other physiological parameters decrease in foxtail millet. However, the addition of OAs, particularly dhaincha and biochar (BC), has shown a promising salt tolerant amendment among others. Its addition improved the growth performance of salinity-stressed plants, including plant height, fresh and dry biomass, simultaneously decreased sodium ion (Na+) and improved calcium (Ca2+), potassium (K+), and nitrate ion (NO3−). They also increased proline build up by 6–17 %, reduced H2O2 (19–38 %) and malondialdehyde (16–18 %). Furthermore, they elevated the relative water content (RWC) (25 %), chlorophyll content, and reduced EL (29–50 %). Once more, dhaincha and BC enhanced the number of rhizobia, phosphorus-solubilizing bacteria (PSB) and overall bacterial population in the soil. In saline soil, daincha and BC could enhance soil organic matter (628 %), total nitrogen (1630 %), available phosphorus (32–38 %), and exchangeable potassium (54–73 %). A potential strategy for improving setaria italica performance under salt is suggested to be the following order, dhaincha > biochar > vermicompost > duckweed. The study would assist stakeholders in these salinity-prone areas in strategizing the use of OAs to their fallow land for cultivation and agricultural activities.

Investigating the growth promotion potential of biochar on pea (Pisum sativum) plants under saline conditions

Pea, member of the plant family Leguminosae, play a pivotal role in global food security as essential legumes. However, their production faces challenges stemming from the detrimental impacts of abiotic stressors, leading to a concerning decline in output. Salinity stress is one of the major factors that limiting the growth and productivity of pea. However, biochar amendment in soil has a potential role in alleviating the oxidative damage caused by salinity stress. The purpose of the study was to evaluate the potential role of biochar amendment in soil that may mitigate the adverse effect of salinity stress on pea. The treatments of this study were, (a) Pea varieties; (i) V1 = Meteor and V2 = Green Grass, Salinity Stress, (b) Control (0 mM) and (ii) Salinity (80 mM) (c) Biochar applications; (i) Control, (ii) 8 g/kg soil (56 g) and (iii) 16 g/kg soil (112 g). Salinity stress demonstrated a considerable reduction in morphological parameters as Shoot and root length decreased by (29% and 47%), fresh weight and dry weight of shoot and root by (85, 63%) and (49, 68%), as well as area of leaf reduced by (71%) among both varieties. Photosynthetic pigments (chlorophyll a, b, and carotenoid contents decreased under 80 mM salinity up to (41, 63, 55 and 76%) in both varieties as compared to control. Exposure of pea plants to salinity stress increased the oxidative damage by enhancing hydrogen peroxide and malondialdehyde content by (79 and 89%), while amendment of biochar reduced their activities as, (56% and 59%) in both varieties. The activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) were increased by biochar applications under salinity stress as, (49, 59, and 86%) as well as non-enzymatic antioxidants as, anthocyanin and flavonoids improved by (112 and 67%). Organic osmolytes such as total soluble proteins, sugars, and glycine betaine were increased up to (57, 83, and 140%) by biochar amendment. Among uptake of mineral ions, shoot and root Na+ uptake was greater (144 and 73%) in saline-stressed plants as compared to control, while shoot and root Ca2+ and K+ were greater up to (175, 119%) and (77, 146%) in biochar-treated plants. Overall findings revealed that 16 g/kg soil (112 g) biochar was found to be effective in reducing salinity toxicity by causing reduction in reactive oxygen species and root and shoot Na+ ions uptake and improving growth, physiological and anti-oxidative activities in pea plants (Fig. 1).Figure 1A schematic diagram represents two different mechanisms of pea under salinity stress (control and 80 mM NaCl) with Biochar (8 and 16 g/kg soil).

Exogenous application of 5-azacitidin, royal jelly and folic acid regulate plant redox state, expression level of DNA methyltransferases and alleviate adverse effects of salinity stress on Vicia faba L. plants

DNA methylation is one of induced changes under salinity stress causing reduction in the expression of several crucial genes required for normal plant's operation. Potential use of royal jelly (RJ), folic acid (FA) and 5-azacitidine (5-AZA) on two Egyptian faba bean varieties (Sakha-3 and Giza-716) grown under saline conditions was investigated. Salinity stress affects negatively on seeds germination (G %), mitotic index, membrane stability and induced a significant increase in chromosomal abnormalities (CAs). DNA methyltransferases genes (MT1 and MT2) were highly up-regulated (∼23 and 8 folds for MT1 and MT2 in shoots of Giza-716 stressed plants). On the other hand, down regulation of other studied stress related genes: superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), heat shock protein (HSP-17.9) and proline-rich protein (GPRP) were detected in stressed plants of both studied varieties. Treating plants with RJ and FA increase G%, chlorophyll content, improves membrane properties and reduces CAs compared to non-treated stressed plants. Exogenous application of 5-AZA, RJ and FA on salinity stressed plants was associated with a significant reduction in the transcription of MT1 and MT2 which was associated with significant up regulation in the expression of Cu/Zn-SOD, CAT, GR, GPRP and HSP-17.9 encoding genes. The Lowest expression of MT1 and MT2 were induced with 5-AZA treatment in both studied varieties. Exogenous application of the FA, RJ and 5-AZA modified the methylation state of stressed plants by regulation the expression of DNA methyltransferases, subsequently, modulated the expression of studied genes and could be proposed as a promising treatment to ameliorate hazardous effects of salt stress on different plants.

Post-synthetic modification of nano-chitosan using gibberellic acid: Foliar application on sorghum under salt stress conditions and estimation of biochemical parameters

The challenge of desert farming with a high salt level has become an ecological task due to salt stress negatively affecting plant growth and reproduction. The current study deals with the cultivation of sorghum under salt stress conditions to counteract the effect of chitosan and gibberellic acid (GA3). Here, the effects of chitosan, GA3 and nano-composite (GA3@chitosan) on biochemical contents, growth and seed yield of sorghum under salinity stress conditions were studied. The results showed that spraying with GA3@chitosan increased sorghum grain yield by 2.07, 1.81 and 1.64 fold higher than salinity stressed plants, chitosan treatment and GA3 treatment, respectively. Additionally, compared to the control of the same variety, the GA3@chitosan spraying treatment improved the concentration of microelements in the grains of the Shandweel-1 and Dorado by 24.51% and 18.39%, respectively for each variety. Furthermore, spraying GA3@chitosan on sorghum varieties increased the accumulation of the macroelements N, P, and K by 34.03%, 47.61%, and 8.67% higher than salt-stressed plants, respectively. On the other hand, the proline and glycinebetaine content in sorghum leaves sprayed with nano-composite were drop by 51.04% and 11.98% less than stressed plants, respectively. The results showed that, in Ras Sudr, the Shandweel-1 variety produced more grain per feddan than the Dorado variety. These findings suggest that GA3@chitosan improves the chemical and biochemical components leading to a decrease in the negative effect of salt stress on the plant which reflects in the high-yield production of cultivated sorghum plants in salt conditions.

Strigolactone-mediated amelioration of salinity stress in bread wheat: Insights from phytochemical and ion channels related genes expression analyses

Foliar application of growth regulators seems to alleviate the adverse effects of abiotic stresses in plants through different mechanisms such as antioxidative and gene expression regulation. As an important abiotic stress, salinity has an enormous negative impact on crop plants such as bread wheat. In the present study, exogenous strigolactone (GR24) was considered for its potential stress-mitigating effect in two contrasting wheats cultivars (‘Arta’ and ‘Karchia’) grown under 2,053,100 mM NaCl stress (10 dS m−1). Yield-related traits, oxidative (APX, POX, CAT, H2O2, MDA, GB and Proline), ionic indices (Na+ and K+ content in leaf and root), and the expression of a selected set of oxidative stress related genes (TaAPX, TaGPX, TaP5CS, TaNHX2, TaSOS1, TaHAK, TaAKT2 and TaHKT2;1) were surveyed in the flowering stage. Strigolactone application (10 μM) had a significant effect on the induction and improvement of biochemical and ionic features such as reducing the electrolyte leakage, H2O2 and MDA or increasing the grain yield, total protein, proline, GB and antioxidant enzymes (APX, POX) activity, of salinity-stressed plants. The gene expression analysis with real-time PCR showed transcriptional variation of selected genes in response to salt stress and GR24. Improved homeostasis in Na+ and K+ and their ratio was found to be correlated with the expression of the antiporter genes and the consequent reduction of ion toxicity. The findings of this study can improve our knowledge about complex mechanism of strigolactone plant hormone during salt stress in crop plans to mitigation of salinity stress.

Transcriptome, Biochemical and Phenotypic Analysis of the Effects of a Precision Engineered Biostimulant for Inducing Salinity Stress Tolerance in Tomato.

Salinity stress is a major problem affecting plant growth and crop productivity. While plant biostimulants have been reported to be an effective solution to tackle salinity stress in different crops, the key genes and metabolic pathways involved in these tolerance processes remain unclear. This study focused on integrating phenotypic, physiological, biochemical and transcriptome data obtained from different tissues of Solanum lycopersicum L. plants (cv. Micro-Tom) subjected to a saline irrigation water program for 61 days (EC: 5.8 dS/m) and treated with a combination of protein hydrolysate and Ascophyllum nodosum-derived biostimulant, namely PSI-475. The biostimulant application was associated with the maintenance of higher K+/Na+ ratios in both young leaf and root tissue and the overexpression of transporter genes related to ion homeostasis (e.g., NHX4, HKT1;2). A more efficient osmotic adjustment was characterized by a significant increase in relative water content (RWC), which most likely was associated with osmolyte accumulation and upregulation of genes related to aquaporins (e.g., PIP2.1, TIP2.1). A higher content of photosynthetic pigments (+19.8% to +27.5%), increased expression of genes involved in photosynthetic efficiency and chlorophyll biosynthesis (e.g., LHC, PORC) and enhanced primary carbon and nitrogen metabolic mechanisms were observed, leading to a higher fruit yield and fruit number (47.5% and 32.5%, respectively). Overall, it can be concluded that the precision engineered PSI-475 biostimulant can provide long-term protective effects on salinity stressed tomato plants through a well-defined mode of action in different plant tissues.

Establishment of seed biopriming in salt stress mitigation of rice plants by mangrove derived Bacillus sp.

Salinity stress is one of the growing challenges for agro-ecosystems. Present study aimed to explore the role of halotolerant bacteria in alleviation of salinity stressed rice plants. Bacillus sp. strain PnD was isolated from Indian Sundarban Mangrove Forest, conferred plant growth promoting (PGP) traits like indole 3-acetic acid (IAA) production, phosphate solubilization, siderophore production but had negative effect of 1-aminoacyclopropane 1-carboxylate (ACC) deaminase activity. Rice seeds (Oryza sativa L.) of Amal-Mana variety were subjected to salinity stress for 24 h by being immersing in 1% NaCl. Another set of seeds were soaked in a broth cultured with Bacillus sp strain PnD, containing 1% NaCl in the media, denoted as bioprimed condition. The seeds that were soaked in distilled water had no salt stress and were not primed, served as control. All the treatments were assigned randomly to the seeds and each treatment was replicated three times resulting in nine experimental units. Completely randomized design was adopted in this experiment. Overall results showed bioprimed seeds soaked in 1% NaCl for 24 h had significantly higher germination percentage, seedling growth, photosynthetic pigments content compared to control and non-primed salinity exposed plants. Scanning electron micrograph revealed root colonization of bacteria in bioprimed seedlings, tissue distortion was also noted during salt stress. The study revealed that Bacillus sp. strain PnD is a potential plant growth promoting bacterium (PGPB), and the seed biopriming technique can efficiently mitigate inhibitory effects of salinity stress in rice plants.

Ameliorating the adverse effects of salinity on wheat plants using the bio-wastes (pomegranate peel extract and /or compost).

Climate changes and the related rise in the frequency of excessive weather proceedings have a strong influence on the physical, chemical, and hydrological processes in soils. Recently the investigators confirmed that the use of biological treatments and resources to overcome abiotic stress is fruitful. Thus, pomegranate peel extract (PPE) because of its high efficacy and/or compost application could improve soil characteristics, soil organic matter and nutrient status. This effect may be referred back to the enhancement in the plant antioxidative defense system against stress conditions. This experiment was done to study the influence of spraying wheat plants with pomegranate peel extract (PPE) with and/or without soil compost added under salt stress on some growth parameters and physiological aspects. Wheat plants were grown in the presence or absence of compost in the soil and foliar sprayed with PPE (600 and 1200 mg L-1) under salt irrigation (3000 and 6000 mg L-1). Growth and yield traits were decreased with salinity stress. High levels of PPE (1200 mg L-1) induced the highest values of osmoprotectants (Total soluble sugars, total soluble protein, proline and free amino acids) in both unstressed or salinity-stressed plants presence or absence compost. Using compost in soil for cultivating wheat plants and PPE spraying treatments increased growth traits photosynthetic pigments and yield components. Moreover, these treatments increased the accumulation of minerals content (N, P, K and Ca) in plants. In general, the results of correlation coefficients showed a significant strong positive relationship among measured yield traits and other tested parameters. The correlation between 1000-grain Wt. and grain Wt./spike (r = 0.94**) was the highest. Meanwhile, a strong negative correlation coefficient between Na% and all yield parameters was recorded. Compost adding to soil and spraying pomegranate peel extract is a successful method for increasing wheat growth, yield and improving the nutritional value of the produced grains under salt stress.

Funneliformis constrictum modulates polyamine metabolism to enhance tolerance of Zea mays L. to salinity

The mechanisms underlie increased stress tolerance in plants of salinity stress in plants by arbuscular mycorrhizal fungi (AMF) are poorly understood, particularly the role of polyamine metabolism. The current study was conducted to investigate how inoculation with the AMF, Funneliformis constrictum, affects maize plant tolerance to salt stress. To this end, we investigated the changes in photosynthesis, redox status, primary metabolites (amino acids) and secondary metabolism (phenolic and polyamine metabolism). Control and inoculated maize plants were grown using different concentrations of diluted seawater (0%, 10%, 20% and 40%). Results revealed that treatment with 10% seawater had a beneficial effect on AMF and its host growth. However, irrigation with 20% and 40% significantly reduced plant growth and biomass. As seawater concentration increased, the plants' reliance on mycorrhizal fungi increased resulting in enhanced growth and photosynthetic pigments contents. Under higher seawater concentrations, inoculation with AMF reduced salinity induced oxidative stress and supported redox homeostasis by reducing H2O2 and MDA levels as well as increasing antioxidant-related enzymes activities (e.g., CAT, SOD, APX, GPX, POX, GR, and GSH). AMF inoculation increased amino acid contents in shoots and roots under control and stress conditions. Amino acids availability provides a route for polyamines biosynthesis, where AMF increased polyamines contents (Put, Spd, Spm, total Pas) and their metabolic enzymes associated (ADC, SAMDC, Spd synthase, and Spm synthase), particularly under 40% seawater irrigation. Consistently, the transcription of genes, involved in polyamine metabolism was also up regulated in salinity-stressed plants. AMF further increased the expression in genes involved in polyamine biosynthesis (ODC, SAMDC, SPDS2 and decreased expression of those in catabolic biosynthesis (ADC and PAO). Overall, inoculation with Funneliformis constrictum could be adopted as a practical strategy to alleviate salinity stress.

The redox status of salinity-stressed Chenopodium quinoa under salicylic acid and sodium nitroprusside treatments.

Spreading the cultivation of crops with high nutritional values such as quinoa demands a wide area of research to overcome the adverse effects of environmental stress. This study aimed at investigating the role of salicylic acid (SA) and sodium nitroprusside (SNP) as a nitric oxide donor, priming at improving the antioxidant defense systems in boosting salinity tolerance in Chenopodium quinoa. These two treatments, SA (0.1 mM) and SNP (0.2 mM), individually or in combination, significantly improved the function of both enzymatic and non-enzymatic antioxidants. SA and SNP priming significantly reduced superoxide dismutase activity, which was accompanied by a significant decrease in hydrogen peroxide accumulation under salinity stress (100 mM NaCl). The SA and SNP treatment increased the activity of enzymatic antioxidants (e.g., catalase, ascorbate peroxidase, peroxidase, and glutathione reductase) and the accumulation of non-enzymatic antioxidants (e.g. ascorbate-glutathione pools, α-tocopherol, phenols, flavonoids, anthocyanins, and carotenoids) to suppress the oxidative stress induced by salinity stress. Under SA and SNP treatment, the upregulation of antioxidant mechanisms induced a significant increase in chlorophyll florescence, chlorophylls, carotenoids, and proteins, as well as a significant reduction in the malondialdehyde content in salinity-stressed plants. In addition, the foliar application of SA or/and SNP led to a significant increase in the accumulation of osmoprotectant molecules of sugars and proline to overcome osmotic stress induced by salinity stress. In conclusion, SA and SNP priming can effectively combat salinity stress through improving the redox status of plants.

Silicon Can Improve Nutrient Uptake and Performance of Black Cumin Under Drought and Salinity Stresses

ABSTRACT The effects of silicon on reducing the damages caused by drought and salinity stresses have been investigated in certain plants. However, little information is available regarding black cumin (Nigella sativa L.) responses. The present pot experiment was conducted to investigate the role of silicon in the nutrient content and biochemical traits of black cumin under conditions of salinity and drought stresses. Osmotic stress was imposed at seven levels of NaCl or polyethylene glycol (PEG) with -0.24, -0.49, and -0.74 MPa and the control treatment. Silicon (control and 1 mM) was applied in the nutrient solution. The results revealed that decreased osmotic potential in both stresses reduced absorption of nitrogen (N), phosphorus (P), potassium (K), copper (Cu), manganese (Mn), iron (Fe), and zinc (Zn) and increased malondialdehyde (MD) and proline in the shoot. There was a significant reduction in the accumulation of these nutrients in the root, except for that of P and N. Silicon also reduced Na concentration in the root and shoot and increased the absorption and distribution of macronutrients and Zn, Fe, Mn, and Cu in salinity stressed plants. We observed an increase in proline and absorption of elements in drought stressed plants employing silicon. In general, silicon could improve plant growth under stress by the osmoregulation and modulation of absorption and distribution of nutrients. However, these beneficial effects were more substantial in salinity stress. We found that silicon participated in decreasing uptake and transfer of toxic ions and improving potassium content.

Inoculation with Azospirillum brasilense and/or Pseudomonas geniculata reinforces flax (Linum usitatissimum) growth by improving physiological activities under saline soil conditions

BackgroundSalinized soils negatively affect plant growth, so it has become necessary to use safe and eco-friendly methods to mitigate this stress. In a completely randomized design, a pot experiment was carried out to estimate the influence of the inoculation with endophytic bacterial isolates Azospirillum brasilense, Pseudomonas geniculata and their co-inoculation on growth and metabolic aspects of flax (Linum usitatissimum) plants that already grown in salinized soil.ResultsThe results observed that inoculation of salinity-stressed flax plants with the endophytes A. brasilense and P. geniculata (individually or in co-inoculation) increases almost growth characteristics (shoot and root lengths, fresh and dry weights as well as number of leaves). Moreover, contents of chlorophylls and carotenoids pigments, soluble sugars, proteins, free proline, total phenols, ascorbic acid, and potassium (K+) in flax plants grown in salinized soil were augmented because of the inoculation with A. brasilense and P. geniculata. Oppositely, there are significant decreases in free proline, malondialdehyde (MDA), hydrogen peroxide (H2O2), and sodium (Na+) contents. Regarding antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX), the inoculation with the tested endophytes led to significant enhancements in the activities of antioxidant enzymes in stressed flax plants.ConclusionsThe results of this work showed that the use of the endophytic bacterial isolates Azospirillum brasilense, Pseudomonas geniculata (individually or in co-inoculation) could be regarded as an uncommon new model to alleviate salinity stress, especially in salinized soils.

Foliar Spray of Biosynthesized Zinc Oxide Nanoparticles Alleviate Salinity Stress Effect on Vicia faba Plants

Previous studies recorded positive impact of ZnO NPs on plants stressed with salinity. The current work was performed to study the effect of two different concentrations of biosynthesized ZnO NPs (50 and 100 mg L−1) on faba bean plants under salinity stress. The zinc oxide nanoparticles (ZnO NPs) were synthesized using Mentha extract, and their shape and size were characterized using X-ray diffraction and transmission electron microscope while diffuse reflectance spectra were measured using UV–Vis spectrophotometer. The generated ZnO NPs were spherical with a particle size 9.4 nm and had a rod form with particle size 15.2 in length and 3.5 nm in width. The response of faba been plants to the foliar spray of ZnO NPs concentrations (0, 50, and 100 mg L−1) alone and in combination with salt stress at 150 mM NaCl was studied. Salinity induced reduction in faba bean root and shoot length and dry/fresh weights, while an enhancement was recorded in response to foliar treatment with ZnO NPs at 50 and 100 mg L−1 either in presence or absence of salinity stress. The highest amounts of chlorophyll a, b, carotenoids, and total pigments were recorded in plants received 50 mg L−1 ZnO NPs compared to the alternative control. Secondary metabolites (phenols, flavonoids, and tannins) were accumulated in salinity-stressed plants and further accumulation in response to ZnO NPs treatment was noticed. Amino acids, proline, glycine betaine, and total soluble sugars, as well as enzymatic and non-enzymatic antioxidant contents, increased almost onefold in salinity-stressed plants as compared to control plants while the 50 mg L−1 ZnO NPs treatment resulted in higher accumulation of the previously mentioned substances. In contrast, plants oxidative stress was reduced in response to ZnO NPs treatments. The nitrogen, phosphorus, potassium, calcium, zinc, and iron contents of faba bean plants were recorded under salinity stress and in response to the two applied concentrations of ZnO NPs. Faba bean plants stressed with 150 MN NaCl showed growth decline that may be attributed to osmotic stress and low water availability imposed by salinity. The treatment of stressed plants with 50 mg L−1 ZnO NPs induced an enhancement in plant growth as well as an accumulation of antioxidants, osmolytes, and secondary metabolites that could help plants overcome the negative effects of salinity.

Salinity Tolerance in a Synthetic Allotetraploid Wheat (SlSlAA) Is Similar to Its Higher Tolerant Parent Aegilops longissima (SlSl) and Linked to Flavonoids Metabolism.

Allotetraploidization between A and S (closely related to B) genome species led to the speciation of allotetraploid wheat (genome BBAA). However, the immediate metabolic outcomes and adaptive changes caused by the allotetraploidization event are poorly understood. Here, we investigated how allotetraploidization affected salinity tolerance using a synthetic allotetraploid wheat line (genome SlSlAA, labeled as 4x), its Aegilops longissima (genome SlSl, labeled as SlSl) and Triticum urartu (AA genome, labeled as AA) parents. We found that the degree of salinity tolerance of 4x was similar to its SlSl parent, and both were substantially more tolerant to salinity stress than AA. This suggests that the SlSl subgenome exerts a dominant effect for this trait in 4x. Compared with SlSl and 4x, the salinity-stressed AA plants did not accumulate a higher concentration of Na+ in leaves, but showed severe membrane peroxidation and accumulated a higher concentration of ROS (H2O2 and O2⋅⁣–) and a lesser concentration of flavonoids, indicating that ROS metabolism plays a key role in saline sensitivity. Exogenous flavonoid application to roots of AA plants significantly relieved salinity-caused injury. Our results suggest that the higher accumulation of flavonoids in SlSl may contribute to ROS scavenging and salinity tolerance, and these physiological properties were stably inherited by the nascent allotetraploid SlSlAA.

Genetic analysis of salinity tolerance in wheat (Triticum aestivum L.).

Understanding the genetics of salt tolerance is of utmost need to combat the rising prevalence of soil salinity through employing tolerant cultivars. The current study was carried out to investigate the quantitative genetic basis of agronomical and physiological-related traits of salinity-stressed plants using seven generations (parental cultivars, F1, F2, F3, BC1, and BC2) of wheat grown in the field under normal and saline conditions. The combined analysis of variance showed highly significant effects of salinity and genotypes (generations) on all the traits. The scaling tests did not support the three-parameter model (additive-dominance model); hence, the six-parameter model was used to assess the genetic effects governing the traits in this study. The epistatic gene effects were crucial, as were additive and dominance gene effects for plant height, K/Na, and yield in salinity stress conditions. The highest heritability was observed for total chlorophyll, carotenoid, SPAD chlorophyll, and K/Na ratio in saline conditions. The additive genetic variance was more important than the dominance variance for grain weight, K, K/Na in salinity conditions. The findings of the current study may have important implications in the quantitative genetics of salinity tolerance and the development of cultivars tolerant to salinity in wheat.

Ampelopsin Confers Endurance and Rehabilitation Mechanisms in Glycine max cv. Sowonkong under Multiple Abiotic Stresses.

The present investigation aims to perceive the effect of exogenous ampelopsin treatment on salinity and heavy metal damaged soybean seedlings (Glycine max L.) in terms of physiochemical and molecular responses. Screening of numerous ampelopsin concentrations (0, 0.1, 1, 5, 10 and 25 μM) on soybean seedling growth indicated that the 1 μM concentration displayed an increase in agronomic traits. The study also determined how ampelopsin application could recover salinity and heavy metal damaged plants. Soybean seedlings were irrigated with water, 1.5% NaCl or 3 mM chosen heavy metals for 12 days. Our results showed that the application of ampelopsin raised survival of the 45-day old salinity and heavy metal stressed soybean plants. The ampelopsin treated plants sustained high chlorophyll, protein, amino acid, fatty acid, salicylic acid, sugar, antioxidant activities and proline contents, and displayed low hydrogen peroxide, lipid metabolism, and abscisic acid contents under unfavorable status. A gene expression survey revealed that ampelopsin application led to the improved expression of GmNAC109, GmFDL19, GmFAD3, GmAPX, GmWRKY12, GmWRKY142, and GmSAP16 genes, and reduced the expression of the GmERF75 gene. This study suggests irrigation with ampelopsin can alleviate plant damage and improve plant yield under stress conditions, especially those including salinity and heavy metals.

Raman spectroscopy-based diagnostics of water deficit and salinity stresses in two accessions of peanut.

Water deficit and salinity are two major abiotic stresses that have tremendous effect on crop yield worldwide. Timely identification of these stresses can help limit associated yield loss. Confirmatory detection and identification of water deficit stress can also enable proper irrigation management. Traditionally, unmanned aerial vehicle (UAV)‐based imaging and satellite‐based imaging, together with visual field observation, are used for diagnostics of such stresses. However, these approaches can only detect salinity and water deficit stress at the symptomatic stage. Raman spectroscopy (RS) is a noninvasive and nondestructive technique that can identify and detect plant biotic and abiotic stress. In this study, we investigated accuracy of Raman‐based diagnostics of water deficit and salinity stresses on two greenhouse‐grown peanut accessions: tolerant and susceptible to water deficit. Plants were grown for 76 days prior to application of the water deficit and salinity stresses. Water deficit treatments received no irrigation for 5 days, and salinity treatments received 1.0 L of 240‐mM salt water per day for the duration of 5‐day sampling. Every day after the stress was imposed, plant leaves were collected and immediately analyzed by a hand‐held Raman spectrometer. RS and chemometrics could identify control and stressed (either water deficit or salinity) susceptible plants with 95% and 80% accuracy just 1 day after treatment. Water deficit and salinity stressed plants could be differentiated from each other with 87% and 86% accuracy, respectively. In the tolerant accessions at the same timepoint, the identification accuracies were 66%, 65%, 67%, and 69% for control, combined stresses, water deficit, and salinity stresses, respectively. The high selectivity and specificity for presymptomatic identification of abiotic stresses in the susceptible line provide evidence for the potential of Raman‐based surveillance in commercial‐scale agriculture and digital farming.

Exogenously applied GA3 promotes plant growth in onion by reducing oxidative stress under saline conditions

Onion (Allium cepa L.) is a biennial crop of high commercial value in Pakistan. Onion is considered as salt sensitive plant species. The present investigation was carried out to investigate the effect of salinity on onion and its alleviation through exogenously applied gibberellic acid (GA3; 100 mg L-1). Foliar application of GA3 (100 mg L-1) was applied on onion seedlings grown under three levels (0, 2 or 4 dS m-1) of salinity after 45 days of sowing. Results revealed that growth parameters and total soluble protein (TSP) contents declined with increase in soil salinity level. While, antioxidant enzyme activities (CAT, SOD and POD) were increased with salinity. However, exogenously applied GA3 significantly enhanced the plant growth and TSP in onion seedlings. Interestingly, CAT, SOD and POD concentration decreased with GA3 application which depicts stress alleviation in saline stressed onion plants due to GA3. It was concluded that the growth of onion could be enhanced to some extent by the application of GA3 under salinity stress.