Insights into the Physiological and Biochemical Impacts of Salt Stress on Plant Growth and Development

Climate change is causing soil salinization, resulting in crop losses throughout the world. The ability of plants to tolerate salt stress is determined by multiple biochemical and molecular pathways. Here we discuss physiological, biochemical, and cellular modulations in plants in response to salt stress. Knowledge of these modulations can assist in assessing salt tolerance potential and the mechanisms underlying salinity tolerance in plants. Salinity-induced cellular damage is highly correlated with generation of reactive oxygen species, ionic imbalance, osmotic damage, and reduced relative water content. Accelerated antioxidant activities and osmotic adjustment by the formation of organic and inorganic osmolytes are significant and effective salinity tolerance mechanisms for crop plants. In addition, polyamines improve salt tolerance by regulating various physiological mechanisms, including rhizogenesis, somatic embryogenesis, maintenance of cell pH, and ionic homeostasis. This research project focuses on three strategies to augment salinity tolerance capacity in agricultural crops: salinity-induced alterations in signaling pathways; signaling of phytohormones, ion channels, and biosensors; and expression of ion transporter genes in crop plants (especially in comparison to halophytes).

Download Full-text

Transcriptomic Analysis of Betula halophila in Response to Salt Stress

International Journal of Molecular Sciences ◽

10.3390/ijms19113412 ◽

2018 ◽

Vol 19 (11) ◽

pp. 3412 ◽

Cited By ~ 10

Author(s):

Fenjuan Shao ◽

Lisha Zhang ◽

Iain Wilson ◽

Deyou Qiu

Keyword(s):

Cell Wall ◽

Salt Stress ◽

Salt Tolerance ◽

Expression Patterns ◽

Soil Salinization ◽

Sphingolipid Metabolism ◽

Sequencing Platform ◽

Resistant Varieties ◽

High Salt Tolerance ◽

Salt Overly Sensitive

Soil salinization is a matter of concern worldwide. It can eventually lead to the desertification of land and severely damage local agricultural production and the ecological environment. Betula halophila is a tree with high salt tolerance, so it is of importance to understand and discover the salt responsive genes of B. halophila for breeding salinity resistant varieties of trees. However, there is no report on the transcriptome in response to salt stress in B. halophila. Using Illumina sequencing platform, approximately 460 M raw reads were generated and assembled into 117,091 unigenes. Among these unigenes, 64,551 unigenes (55.12%) were annotated with gene descriptions, while the other 44.88% were unknown. 168 up-regulated genes and 351 down-regulated genes were identified, respectively. These Differentially Expressed Genes (DEGs) involved in multiple pathways including the Salt Overly Sensitive (SOS) pathway, ion transport and uptake, antioxidant enzyme, ABA signal pathway and so on. The gene ontology (GO) enrichments suggested that the DEGs were mainly involved in a plant-type cell wall organization biological process, cell wall cellular component, and structural constituent of cell wall molecular function. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment showed that the top-four enriched pathways were ‘Fatty acid elongation’, ‘Ribosome’, ‘Sphingolipid metabolism’ and ‘Flavonoid biosynthesis’. The expression patterns of sixteen DEGs were analyzed by qRT-PCR to verify the RNA-seq data. Among them, the transcription factor AT-Hook Motif Nuclear Localized gene and dehydrins might play an important role in response to salt stress in B. halophila. Our results provide an important gene resource to breed salt tolerant plants and useful information for further elucidation of the molecular mechanism of salt tolerance in B. halophila.

Download Full-text

Exogenous Melatonin Improves Salt Tolerance by Mitigating Osmotic, Ion, and Oxidative Stresses in Maize Seedlings

Agronomy ◽

10.3390/agronomy10050663 ◽

2020 ◽

Vol 10 (5) ◽

pp. 663 ◽

Cited By ~ 3

Author(s):

Jianhong Ren ◽

Jun Ye ◽

Lina Yin ◽

Gouxia Li ◽

Xiping Deng ◽

...

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Antioxidant Activities ◽

Term Treatment ◽

Plant Tolerance ◽

Short Term Treatment ◽

Exogenous Melatonin ◽

Positive Effects ◽

Oxidative Stresses

Melatonin has been confirmed extensively for the positive effects on increasing plant tolerance to various abiotic stresses. However, the roles of melatonin in mediating different stresses still need to be explored in different plants species and growth periods. To investigate the role of melatonin in mitigating salt stress, maize (Zea mays L.) seedlings growing in hydroponic solution were treated with 100 mM NaCl combined with or without 1 μM melatonin. Melatonin application had no effects on maize growth under normal condition, while it moderately alleviated the NaCl-induced inhibition of plant growth. The leaf area, biomass, and photosynthesis of melatonin-treated plants were higher than that of without melatonin under NaCl treatment. The osmotic potential was lower, and the osmolyte contents (including sucrose and fructose) were higher in melatonin-treated plants. Meanwhile, the decreases in Na+ content and increases in K+/Na+ ratio were found in shoots of melatonin-applied plant under salt stress. Moreover, both enzymatic and nonenzymatic antioxidant activities were significantly increased in leaves with melatonin application under salt treatment. These results clearly indicate that the exogenous melatonin-enhanced salt tolerance under short-term treatment could be ascribed to three aspects, including osmotic adjustment, ion balance, and alleviation of salt-induced oxidative stress.

Download Full-text

Matching physiological traits and ion concentrations associated with salt stress in cowpea genotypes

Australian Journal of Agricultural Research ◽

10.1071/ar01133 ◽

2002 ◽

Vol 53 (11) ◽

pp. 1243 ◽

Cited By ~ 10

Author(s):

Bernardo Murillo-Amadot ◽

Enrique Troyo-Diéguez ◽

Raúl López-Aguilar ◽

Alejandro López-Cortés ◽

Clara L. Tinoco-Ojanguri ◽

...

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Salinity Tolerance ◽

Growth Stage ◽

Seedling Survival ◽

Nutrient Deficiency ◽

Chloride Concentration ◽

Sodium Concentration ◽

Ion Concentrations ◽

Survival Percentage

The salt tolerance of 25 cowpea genotypes (Vigna unguiculata L. Walp.) was studied during early vegetative growth. Salinity treatments were applied by irrigating with a nutrient solution containing 0, 85, and 170 mmol NaCl/L. Seedling survival decreased linearly as salinity increased, but this enabled cowpea genotypes to be ranked for salinity tolerance according to the magnitudes of slopes of regression of survival percentage on salinity. Sodium concentration was higher in roots than in shoots in all genotypes, and increased significantly in both roots and shoots as salinity increased. Chloride concentration in both roots and shoots increased with increasing salinity in all genotypes, and was higher in shoots than in roots at 85 and 170 mmol NaCl/L. In some cases, Ca, Mg, K, and P concentrations were reduced by an increase in salinity, but none of the genotypes appeared to suffer any nutrient deficiency. We observed wide differences in responses to salinity, and our results suggest that during the growth stage studied, 7 of the 25 genotppes tested could be classified as tolerant or relatively tolerant to salinity (Sonorense, CB3, CB27, Cuarenteño, CB46, Paceño, and IT82D-889).

Download Full-text

Physiological and Biochemical Responses to Salt Stress of Alfalfa Populations Selected for Salinity Tolerance and Grown in Symbiosis with Salt-Tolerant Rhizobium

Agronomy ◽

10.3390/agronomy10040569 ◽

2020 ◽

Vol 10 (4) ◽

pp. 569

Author(s):

Annick Bertrand ◽

Craig Gatzke ◽

Marie Bipfubusa ◽

Vicky Lévesque ◽

Francois P. Chalifour ◽

...

Keyword(s):

Amino Acids ◽

Salt Stress ◽

Salt Tolerance ◽

Water Content ◽

Salinity Tolerance ◽

Osmotic Adjustment ◽

Recurrent Selection ◽

Aromatic Amino Acids ◽

Nacl Stress ◽

Salt Tolerant

Alfalfa and its rhizobial symbiont are sensitive to salinity. We compared the physiological responses of alfalfa populations inoculated with a salt-tolerant rhizobium strain, exposed to five NaCl concentrations (0, 20, 40, 80, or 160 mM NaCl). Two initial cultivars, Halo (H-TS0) and Bridgeview (B-TS0), and two populations obtained after three cycles of recurrent selection for salt tolerance (H-TS3 and B-TS3) were compared. Biomass, relative water content, carbohydrates, and amino acids concentrations in leaves and nodules were measured. The higher yield of TS3-populations than initial cultivars under salt stress showed the effectiveness of our selection method to improve salinity tolerance. Higher relative root water content in TS3 populations suggests that root osmotic adjustment is one of the mechanisms of salt tolerance. Higher concentrations of sucrose, pinitol, and amino acid in leaves and nodules under salt stress contributed to the osmotic adjustment in alfalfa. Cultivars differed in their response to recurrent selection: under a 160 mM NaCl-stress, aromatic amino acids and branched-chain amino acids (BCAAs) increased in nodules of B-ST3 as compared with B-TS0, while these accumulations were not observed in H-TS3. BCAAs are known to control bacteroid development and their accumulation under severe stress could have contributed to the high nodulation of B-TS3.

Download Full-text

Responses of Tolerant and Susceptible Kentucky Bluegrass Germplasm to Salt Stress

Journal of the American Society for Horticultural Science ◽

10.21273/jashs03755-16 ◽

2016 ◽

Vol 141 (5) ◽

pp. 449-456 ◽

Cited By ~ 3

Author(s):

B. Shaun Bushman ◽

Lijun Wang ◽

Xin Dai ◽

Alpana Joshi ◽

Joseph G. Robins ◽

...

Keyword(s):

Salt Stress ◽

Antioxidant Activities ◽

Poa Pratensis ◽

Inorganic Ions ◽

Kentucky Bluegrass ◽

Western North America ◽

Turf Quality ◽

Ionic Stress ◽

Highly Correlated ◽

Eventual Death

Much of semiarid western North America is salt affected, and using turfgrasses in salty areas can be challenging. Kentucky bluegrass (Poa pratensis L.) is relatively susceptible to salt stress, showing reduced growth, osmotic and ionic stress, and eventual death at moderate or high salt concentrations. Considerable variation exists for salt tolerance among kentucky bluegrass germplasm, but gaining consistency among studies and entries has been a challenge. In this study, two novel kentucky bluegrass accessions recently reported as salt tolerant (PI 371768 and PI 440603) and two cultivars commonly used as references (Baron and Midnight) were compared for their turf quality (TQ), stomatal conductance (gS), leaf water potential (ψLEAF), electrolyte leakage (EL), and accumulation of inorganic ions under salt stress. TQ, ψLEAF, and EL were highly correlated with each other while only moderately correlated with gS. The tolerant accessions showed higher ψLEAF and lower EL than the cultivars Midnight and Baron at increasing salt concentrations and over 28 days of treatment. The accumulation of sodium (Na) and calcium (Ca) in the leaves was highly correlated and did not vary significantly among the four entries. Genes involved in ion transport across membranes, and in antioxidant activities, were significantly induced on salt stress in the tolerant accessions relative to the susceptible. These data indicate the ability of tolerant accessions to ameliorate oxidative stress and prevent EL, and confirmed the tolerance of germplasm previously reported on while indicating mechanisms by which they tolerate the salt stress.

Download Full-text

QTLs for seedling traits under salinity stress in hexaploid wheat

Ciência Rural ◽

10.1590/0103-8478cr20170446 ◽

2018 ◽

Vol 48 (3) ◽

Cited By ~ 2

Author(s):

Yongzhe Ren ◽

Yanhua Xu ◽

Wan Teng ◽

Bin Li ◽

Tongbao Lin

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Salinity Tolerance ◽

Hexaploid Wheat ◽

Dry Weight ◽

Interval Mapping ◽

Mapping Method ◽

Stress Conditions ◽

Wheat Varieties ◽

Seedling Traits

ABSTRACT: Soil salinity limits agricultural production and is a major obstacle for increasing crop yield. Common wheat is one of the most important crops with allohexaploid characteristic and a highly complex genome. QTL mapping is a useful way to identify genes for quantitative traits such as salinity tolerance in hexaploid wheat. In the present study, a hydroponic trial was carried out to identify quantitative trait loci (QTLs) associated with salinity tolerance of wheat under 150mM NaCl concentration using a recombinant inbred line population (Xiaoyan 54×Jing 411). Values of wheat seedling traits including maximum root length (MRL), root dry weight (RDW), shoot dry weight (SDW), total dry weight (TDW) and the ratio of TDW of wheat plants between salt stress and control (TDWR) were evaluated or calculated. A total of 19QTLs for five traits were detected through composite interval mapping method by using QTL Cartographer version 2.5 under normal and salt stress conditions. These QTLs distributed on 12 chromosomes explained the percentage of phenotypic variation by individual QTL varying from 7.9% to 19.0%. Among them, 11 and six QTLs were detected under normal and salt stress conditions, respectively and two QTLs were detected for TDWR. Some salt tolerance related loci may be pleiotropic. Chromosome 1A, 3A and 7A may harbor crucial candidate genes associated with wheat salt tolerance. Our results would be helpful for the marker assisted selection to breed wheat varieties with improved salt tolerance.

Download Full-text

Foliar Application of 24-Epibrassinolide Improved Salt Stress Tolerance of Perennial Ryegrass

HortScience ◽

10.21273/hortsci.50.10.1518 ◽

2015 ◽

Vol 50 (10) ◽

pp. 1518-1523 ◽

Cited By ~ 13

Author(s):

Shanshan Sun ◽

Mengying An ◽

Liebao Han ◽

Shuxia Yin

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Stress Tolerance ◽

Perennial Ryegrass ◽

Foliar Application ◽

Soluble Sugar ◽

Salt Stress Tolerance ◽

Salt Stress Condition ◽

Relative Water ◽

Antioxidant Defense Systems

Perennial ryegrass (Lolium perenne L.) is a widely used turfgrass. In this study, the effect of exogenously applied 24-epibrassinolide (EBR) on salt stress tolerance of perennial ryegrass was investigated. The results indicated that pretreatment with four concentrations of EBR (0, 0.1, 10, 1000 nM) improved salt tolerance of perennial ryegrass. Exogenous EBR treatment decreased electrolyte leakage (EL), malondialdehyde (MDA), and H2O2 contents and enhanced the leaf relative water content (RWC), proline, soluble sugar, and soluble protein content under salt stress condition. Meanwhile, EBR reduced the accumulation of Na+ and increased K+, Ca2+, and Mg2+ contents in leaves after salt treatment. Moreover, EBR pretreatment also increased superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) activity, as well as ascorbic acid (AsA) and glutathione contents. These results suggested that EBR improved salt tolerance by enhancing osmotic adjustment and antioxidant defense systems in perennial ryegrass.

Download Full-text

Physiological responses of crop plants against Trichoderma harzianum in saline environment

Acta Botanica Croatica ◽

10.1515/botcro-2016-0054 ◽

2017 ◽

Vol 76 (2) ◽

pp. 154-162 ◽

Cited By ~ 11

Author(s):

Roomana Yasmeen ◽

Zamin Shaheed Siddiqui

Keyword(s):

Salt Stress ◽

Trichoderma Harzianum ◽

Physiological Role ◽

Photosynthetic Performance ◽

Crop Plants ◽

Salt Treatment ◽

Saline Environment ◽

Relative Water ◽

Stress Environment

AbstractThe physiological response of crop plants againstTrichoderma harzianum(Th-6) in a saline habitat was studied.Trichoderma harzianum(Th-6) is an endophytic fungus that shows salt tolerance and establishes a symbiotic relationship with a host plant. To evaluate the role ofTrichoderma harzianum(Th-6) in mitigating the consequences of salinity stress on crop plants, seeds of maize and rice were coated withTrichodermabefore sowing and salt treatment. Later, after germination, twenty-one day old seedlings were subjected to NaCl concentrations (50, 100 and 150 mM). Salinity negatively affected all investigated physiological parameters in both crops. Treatment of seeds withTrichodermaimproved plant growth andTh-treated plants exhibited substantial physiological adjustment in a saline environment compared toTh-untreated plants. TheTh-treated plants under salt stress showed higher relative water content and stomatal conductance, better photosynthetic performance and higher pigment concentrations, as well as higher catalase and superoxide dismutase activities. Moreover, proline content in salt stress environment was higher inTh-treated plants, while H2O2content declined. The physiological role ofTrichoderma harzianumin mitigating the salt related consequences of both crop plants is discussed.

Download Full-text

Genomic and transcriptomic analysis reveal molecular basis of salinity tolerance in a novel strong salt-tolerant rice landrace Changmaogu

Rice ◽

10.1186/s12284-019-0360-4 ◽

2019 ◽

Vol 12 (1) ◽

Cited By ~ 3

Author(s):

Bing-Rui Sun ◽

Chong-Yun Fu ◽

Zhi-Lan Fan ◽

Yu Chen ◽

Wen-Feng Chen ◽

...

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Salinity Tolerance ◽

Molecular Basis ◽

Carotenoid Biosynthesis ◽

Seedling Stage ◽

Differentially Expressed ◽

Salt Tolerant ◽

Transcriptomic Sequencing ◽

Rice Landrace

Abstract Background Salt stress is an important factor that limits rice yield. We identified a novel, strongly salt tolerant rice landrace called Changmaogu (CMG) collected from a coastal beach of Zhanjiang, Guangdong Province, China. The salt tolerance of CMG was much better than that of the international recognized salt tolerant rice cultivar Pokkali in the germination and seedling stages. Results To understand the molecular basis of salt tolerance in CMG, we performed BSA-seq for two extreme bulks derived from the cross between CMG and a cultivar sensitive to salt, Zhefu802. Transcriptomic sequencing was conducted for CMG at the germination and young seedling stages. Six candidate regions for salt tolerance were mapped on Chromosome 1 by BSA-seq using the extreme populations. Based on the polymorphisms identified between both parents, we detected 32 genes containing nonsynonymous coding single nucleotide polymorphisms (SNPs) and frameshift mutations in the open reading frame (ORF) regions. With transcriptomic sequencing, we detected a large number of differentially expressed genes (DEGs) at the germination and seedling stages under salt stress. KEGG analysis indicated two of 69 DEGs shared at the germination and seedling stages were significantly enriched in the pathway of carotenoid biosynthesis. Of the 169 overlapping DEGs among three sample points at the seedling stage, 13 and six DEGs were clustered into the pathways of ABA signal transduction and carotenoid biosynthesis, respectively. Of the 32 genes carrying sequence variation, only OsPP2C8 (Os01g0656200) was differentially expressed in the young seedling stage under salt stress and also showed sequence polymorphism in the ORFs between CMG and Zhefu802. Conclusion OsPP2C8 was identified as the target candidate gene for salinity tolerance in the seedling stage. This provides an important genetic resource for the breeding of novel salt tolerant rice cultivars.

Download Full-text

Early effects of salt stress on the physiological and oxidative status of the halophyte Lobularia maritima

Functional Plant Biology ◽

10.1071/fp19303 ◽

2020 ◽

Vol 47 (10) ◽

pp. 912

Author(s):

Anis Ben Hsouna ◽

Thaura Ghneim-Herrera ◽

Walid Ben Romdhane ◽

Amira Dabbous ◽

Rania Ben Saad ◽

...

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Expression Profiles ◽

Ion Homeostasis ◽

Accumulation Pattern ◽

Moderate Salinity ◽

Lobularia Maritima ◽

Early Effects ◽

Stress Related Genes ◽

Ionic Imbalance

Soil salinity is an abiotic stress that reduces agricultural productivity. For decades, halophytes have been studied to elucidate the physiological and biochemical processes involved in alleviating cellular ionic imbalance and conferring salt tolerance. Recently, several interesting genes with proven influence on salt tolerance were isolated from the Mediterranean halophyte Lobularia maritima (L.) Desv. A better understanding of salt response in this species is needed to exploit its potential as a source of stress-related genes. We report the characterisation of L. maritima’s response to increasing NaCl concentrations (100–400 mM) at the physiological, biochemical and molecular levels. L. maritima growth was unaffected by salinity up to 100 mM NaCl and it was able to survive at 400 mM NaCl without exhibiting visual symptoms of damage. Lobularia maritima showed a Na+ and K+ accumulation pattern typical of a salt-includer halophyte, with higher contents of Na+ in the leaves and K+ in the roots of salt-treated plants. The expression profiles of NHX1, SOS1, HKT1, KT1 and VHA-E1 in salt-treated plants matched this Na+ and K+ accumulation pattern, suggesting an important role for these transporters in the regulation of ion homeostasis in leaves and roots of L. maritima. A concomitant stimulation in phenolic biosynthesis and antioxidant enzyme activity was observed under moderate salinity, suggesting a potential link between the production of polyphenolic antioxidants and protection against salt stress in L. maritima. Our findings indicate that the halophyte L. maritima can rapidly develop physiological and antioxidant mechanisms to adapt to salt and manage oxidative stress.

Download Full-text