Contribution of Rhizobium–Legume Symbiosis in Salt Stress Tolerance in Medicago truncatula Evaluated through Photosynthesis, Antioxidant Enzymes, and Compatible Solutes Accumulation

The effects of salt stress on the growth, nodulation, and nitrogen (N) fixation of legumes are well known, but the relationship between symbiotic nitrogen fixation (SNF) driven by rhizobium–legume symbiosis and salt tolerance in Medicago truncatula is not well studied. The effects of the active nodulation process on salt stress tolerance of Medicago truncatula were evaluated by quantifying the compatible solutes, soluble sugars, and antioxidants enzymes, as well as growth and survival rate of plants. Eight weeks old plants, divided in three groups: (i) no nodules (NN), (ii) inactive nodules (IN), and (iii) active nodules (AN), were exposed to 150 mM of NaCl salt stress for 0, 8, 16, 24, 32, 40, and 48 h in hydroponic system. AN plants showed a higher survival rate (30.83% and 38.35%), chlorophyll contents (37.18% and 44.51%), and photosynthesis compared to IN and NN plants, respectively. Improved salt tolerance in AN plants was linked with higher activities of enzymatic and nonenzymatic antioxidants and higher K+ (20.45% and 39.21%) and lower Na+ accumulations (17.54% and 24.51%) when compared with IN and NN plants, respectively. Additionally, higher generation of reactive oxygen species (ROS) was indicative of salt stress, causing membrane damage as revealed by higher electrolyte leakage and lipid peroxidation. All such effects were significantly ameliorated in AN plants, showing higher compatible solutes (proline, free amino acids, glycine betaine, soluble sugars, and proteins) and maintaining higher relative water contents (61.34%). This study advocates positive role of Rhizobium meliloti inoculation against salt stress through upregulation of antioxidant system and a higher concentration of compatible solutes.

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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.

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Temporal salt stress-induced transcriptome alterations and regulatory mechanisms revealed by PacBio long-reads RNA sequencing in Gossypium hirsutum

BMC Genomics ◽

10.1186/s12864-020-07260-z ◽

2020 ◽

Vol 21 (1) ◽

Author(s):

Delong Wang ◽

Xuke Lu ◽

Xiugui Chen ◽

Shuai Wang ◽

Junjuan Wang ◽

...

Keyword(s):

Superoxide Dismutase ◽

Salt Stress ◽

Stress Response ◽

Salt Tolerance ◽

Gossypium Hirsutum ◽

Stress Tolerance ◽

Economic Losses ◽

Salt Tolerant ◽

Salt Stress Tolerance ◽

Long Reads

Abstract Background Cotton (Gossypium hirsutum) is considered a fairly salt tolerant crop however, salinity can still cause significant economic losses by affecting the yield and deteriorating the fiber quality. We studied a salt-tolerant upland cotton cultivar under temporal salt stress to unfold the salt tolerance molecular mechanisms. Biochemical response to salt stress (400 mM) was measured at 0 h, 3 h, 12 h, 24 h and 48 h post stress intervals and single-molecule long-read sequencing technology from Pacific Biosciences (PacBio) combined with the unique molecular identifiers approach was used to identify differentially expressed genes (DEG). Results Antioxidant enzymes including, catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) were found significantly induced under temporal salt stress, suggesting that reactive oxygen species scavenging antioxidant machinery is an essential component of salt tolerance mechanism in cotton. We identified a wealth of novel transcripts based on the PacBio long reads sequencing approach. Prolonged salt stress duration induces high number of DEGs. Significant numbers of DEGs were found under key terms related to stress pathways such as “response to oxidative stress”, “response to salt stress”, “response to water deprivation”, “cation transport”, “metal ion transport”, “superoxide dismutase”, and “reductase”. Key DEGs related to hormone (abscisic acid, ethylene and jasmonic acid) biosynthesis, ion homeostasis (CBL-interacting serine/threonine-protein kinase genes, calcium-binding proteins, potassium transporter genes, potassium channel genes, sodium/hydrogen exchanger or antiporter genes), antioxidant activity (POD, SOD, CAT, glutathione reductase), transcription factors (myeloblastosis, WRKY, Apetala 2) and cell wall modification were found highly active in response to salt stress in cotton. Expression fold change of these DEGs showed both positive and negative responses, highlighting the complex nature of salt stress tolerance mechanisms in cotton. Conclusion Collectively, this study provides a good insight into the regulatory mechanism under salt stress in cotton and lays the foundation for further improvement of salt stress tolerance.

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A Medicago truncatula EF-Hand Family Gene, MtCaMP1, Is Involved in Drought and Salt Stress Tolerance

PLoS ONE ◽

10.1371/journal.pone.0058952 ◽

2013 ◽

Vol 8 (4) ◽

pp. e58952 ◽

Cited By ~ 19

Author(s):

Tian-Zuo Wang ◽

Jin-Li Zhang ◽

Qiu-Ying Tian ◽

Min-Gui Zhao ◽

Wen-Hao Zhang

Keyword(s):

Salt Stress ◽

Stress Tolerance ◽

Medicago Truncatula ◽

Salt Stress Tolerance ◽

Ef Hand ◽

Drought And Salt Stress ◽

Family Gene

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Evaluation of salt tolerance in Eruca sativa accessions based on morpho-physiological traits

PeerJ ◽

10.7717/peerj.9749 ◽

2020 ◽

Vol 8 ◽

pp. e9749

Author(s):

Sadia Afsar ◽

Gulnaz Bibi ◽

Raza Ahmad ◽

Muhammad Bilal ◽

Tatheer Alam Naqvi ◽

...

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Stress Tolerance ◽

Abiotic Stresses ◽

Large Scale ◽

Physiological Traits ◽

Eruca Sativa ◽

Salt Stress Tolerance ◽

Gas Exchange Parameters ◽

Geographical Regions

Background Salinity is one of the most lethal abiotic stresses which affect multiple aspects of plant physiology. Natural variations in plant germplasm are a great resource that could be exploited for improvement in salt tolerance. Eruca sativa (E. sativa) exhibits tolerance to abiotic stresses. However, thorough evaluation of its salt stress tolerance and screening for traits that could be reliably applied for salt tolerance needs to be studied. The current study was designed to characterize 25 E. sativa accessions, originating from diverse geographical regions of Pakistan, for the salt stress tolerance. Methods Salt stress (150 mM NaCl) was applied for 2 weeks to the plants at four leaf stage in hydroponics. Data of the following morpho-physiological traits were collected from control and treated plants of all the accessions: root length (RL), shoot length (SL), plant height (PH), leaf number (LN), leaf area (LA), fresh weight (FW), dry weight (DW), chlorophyl content (SPAD), electrolyte leakage (EL), relative water content (RWC), gas exchange parameters and mineral ion content. Salt tolerance was determined based on membership function value (MFV) of the tested traits. Results Compared with control, the salt-stressed group had significantly reduced mean SL, RL, PH, LN, LA, FW, DW and SPAD. NaCl treatment triggered a slight increase in EL in few accessions. Mean RWC of control and treated groups were not significantly different although few accessions exhibited variation in this trait. Salt stress caused a significant reduction in photosynthesis rate (PR), transpiration rate (TR) and stomatal conductance (SC) but intercellular CO2 (Ci) was not significantly different between control and treated groups. Compared with control, the salt-stressed plants accumulated significantly higher Na+, K+ and Ca2+ while significantly lower Mg2+. K+/Na+ ratio was significantly decreased in salt-stressed plants compared with control. Importantly, significant inter-accession variations were found for all the tested traits. The principal component analysis identified SL, RL, PH, LN, LA, FW, DW and PR as the most significant traits for resolving inter-accession variability. Based on MFV of the tested traits, accessions were categorized into five standard groups. Among 25 accessions, one accession was ranked as highly tolerant, four as tolerant while 15 accessions were ranked as moderately tolerant. Of the remaining five accessions, four were ranked as sensitive while one accession as highly sensitive. Conclusion E. sativa accessions were found to exhibit significant genetic diversity in all the tested traits. A few most significant traits for dissecting the genetic variability were identified that could be used for future large-scale germplasm screening in E. sativa. Salt tolerant accessions could be a good resource for future breeding programs aiming to improve salt stress tolerance.

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Soybean GmMYB133 Inhibits Hypocotyl Elongation and Confers Salt Tolerance in Arabidopsis

Frontiers in Plant Science ◽

10.3389/fpls.2021.764074 ◽

2021 ◽

Vol 12 ◽

Author(s):

Binghui Shan ◽

Wei Wang ◽

Jinfeng Cao ◽

Siqi Xia ◽

Ruihua Li ◽

...

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Plant Growth ◽

Stress Tolerance ◽

Stress Responses ◽

Agronomic Traits ◽

Salt Stress Tolerance ◽

Developmental Defects ◽

Functional Roles ◽

Regulatory Module

REVEILLE (RVE) genes generally act as core circadian oscillators to regulate multiple developmental events and stress responses in plants. It is of importance to document their roles in crops for utilizing them to improve agronomic traits. Soybean is one of the most important crops worldwide. However, the knowledge regarding the functional roles of RVEs is extremely limited in soybean. In this study, the soybean gene GmMYB133 was shown to be homologous to the RVE8 clade genes of Arabidopsis. GmMYB133 displayed a non-rhythmical but salt-inducible expression pattern. Like AtRVE8, overexpression of GmMYB133 in Arabidopsis led to developmental defects such as short hypocotyl and late flowering. Seven light-responsive or auxin-associated genes including AtPIF4 were transcriptionally depressed by GmMYB133, suggesting that GmMYB133 might negatively regulate plant growth. Noticeably, the overexpression of GmMYB133 in Arabidopsis promoted seed germination and plant growth under salt stress, and the contents of chlorophylls and malondialdehyde (MDA) were also enhanced and decreased, respectively. Consistently, the expressions of four positive regulators responsive to salt tolerance were remarkably elevated by GmMYB133 overexpression, indicating that GmMYB133 might confer salt stress tolerance. Further observation showed that GmMYB133 overexpression perturbed the clock rhythm of AtPRR5, and yeast one-hybrid assay indicated that GmMYB133 could bind to the AtPRR5 promoter. Moreover, the retrieved ChIP-Seq data showed that AtPRR5 could directly target five clients including AtPIF4. Thus, a regulatory module GmMYB133-PRR5-PIF4 was proposed to regulate plant growth and salt stress tolerance. These findings laid a foundation to further address the functional roles of GmMYB133 and its regulatory mechanisms in soybean.

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Effects, tolerance mechanisms and management of salt stress in lucerne (Medicago sativa)

Crop and Pasture Science ◽

10.1071/cp20033 ◽

2020 ◽

Vol 71 (5) ◽

pp. 411 ◽

Cited By ~ 1

Author(s):

Safaa Mohammed Al-Farsi ◽

Ahmad Nawaz ◽

Anees-ur-Rehman ◽

Saleem K. Nadaf ◽

Abdullah M. Al-Sadi ◽

...

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Medicago Sativa ◽

Hormonal Regulation ◽

Soluble Sugars ◽

Compatible Solutes ◽

Enzyme Activation ◽

Plant Growth Promoting Bacteria ◽

Dry Matter Accumulation ◽

Tolerance Mechanisms

Lucerne (alfalfa, Medicago sativa L.) is a forage legume that is widely cultivated in arid and semi-arid regions of the world. The main aim of this review was to highlight the effects of salt stress on the performance of lucerne and to suggest different tolerance mechanisms and management strategies for improving its yield under salt stress. Salt stress significantly affects seed germination, carbon fixation, light harvesting, biological N2 fixation, mineral uptake and assimilation and dry-matter accumulation in lucerne. Accumulation of osmolytes or compatible solutes such as proline, polyamines, trehalose and soluble sugars confers salt tolerance in lucerne. Maintenance of low Na+:K+ ratios, antioxidant enzyme activation, and hormonal regulation also help lucerne to withstand salt stress. The screening of diverse genotypes on the basis of germination indices, gas exchange, biomass production, lipid peroxidation and antioxidant enzymes might be useful for breeding salt-tolerant lucerne genotypes. Novel biotechnological tools and functional genomics used to identify salt-conferring genes and quantitative trait loci will help to improve salt tolerance. Use of rhizobial and non-rhizobial plant growth-promoting bacteria, arbuscular mycorrhizal fungi, exogenous application of osmoprotectants, and seed priming with brassinolide, gibberellic acid and salicylic acid may help to improve lucerne performance in saline environments.

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Alternative oxidase 1 (Aox1) gene expression in roots of Medicago truncatula is a genotype-specific component of salt stress tolerance

Journal of Plant Physiology ◽

10.1016/j.jplph.2012.08.017 ◽

2013 ◽

Vol 170 (1) ◽

pp. 111-114 ◽

Cited By ~ 26

Author(s):

Haythem Mhadhbi ◽

Vasileios Fotopoulos ◽

Photini V. Mylona ◽

Moez Jebara ◽

Mohamed Elarbi Aouani ◽

...

Keyword(s):

Gene Expression ◽

Salt Stress ◽

Stress Tolerance ◽

Medicago Truncatula ◽

Alternative Oxidase ◽

Salt Stress Tolerance ◽

Specific Component

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Early Detection of Salt Stress Tolerance of Prunus Rootstocks by Excised Root Culture

HortScience ◽

10.21273/hortsci.46.1.80 ◽

2011 ◽

Vol 46 (1) ◽

pp. 80-85 ◽

Cited By ~ 3

Author(s):

Pilar Andreu ◽

Arancha Arbeloa ◽

Pilar Lorente ◽

Juan A. Marín

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Early Detection ◽

Stress Tolerance ◽

Starch Accumulation ◽

Genotypic Differences ◽

Root Cultures ◽

Salt Stress Tolerance ◽

Root Tips

Salt tolerance varies between species and genotypes of plants, but evaluation of these differences is cumbersome, because whole plants that are highly complex systems show a variety of responses depending on the applied methodology. However, focusing on plant roots, which are in direct contact with the soil, could offer a simpler and more efficient model for analyzing salt stress tolerance in different species. This study explores whether root growth under salt stress is associated with genotypic differences in Prunus species with different degrees of salt tolerance. Excised root cultures were grown in vitro under increasing salt concentrations (0, 20, 60, and 180 mm NaCl). Root tips taken from in vitro-rooted shoots of Prunus species with different salt tolerance were measured after 3 weeks of culture in a shaker, and changes in their anatomy were examined. Both growth and starch content of in vitro root cultures were affected by salt concentration. Root length increments were related to salt stress tolerance at 60 mm NaCl, in which significant differences were also found between species. A significant inverse correlation was found between salt tolerance and starch accumulation in the maturation zone of root tips. Genotypic differences were observed in agreement with species' salt stress tolerance in vivo. These results suggest the use of excised root cultures for rapid, early detection of salt stress tolerance in plants. Chemical names: sodium chloride (NaCl).

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