Differential Responses of CO2 Assimilation, Carbohydrate Allocation and Gene Expression to NaCl Stress in Perennial Ryegrass with Different Salt Tolerance

Plants possess abiotic stress responses that alter photosynthetic metabolism under salinity stress. The objective of this study was to identify the stomatal and metabolic changes associated with photosynthetic responses to NaCl stress in perennial ryegrass (Lolium perenne). Five-week-old seedlings of two perennial ryegrass genotypes, PI 516605 (salt-sensitive) and BARLP 4317 (salt-tolerant), were subjected to 0 and 250 mm NaCl for 8 days. The salt tolerance in perennial ryegrass was significantly associated with leaf relative water content (RWC) and photosynthetic capacity through the maintenance of greater metabolic activities under prolonged salt stress. BARLP 4317 maintained greater turf quality, RWC, and stomatal limitations but a lower level of lipid peroxidation [malondialdehyde (MDA)] and intercellular CO2 concentration than PI 516605 at 8 days after treatment (DAT). Ribulose-1, 5-bisphosphate carboxylase:oxygenase (Rubisco) activity and activation state, transcriptional level of rbcL gene, and expression level of Rubisco large subunit (LSU) declined in stressed perennial ryegrass but were higher in salt-tolerant genotype at 8 DAT. Furthermore, photosynthetic rate increased linearly with increasing Rubisco activity, Rubisco activation state, and RWC in both genotypes. The same linear relationship was found between RWC and Rubisco activity. However, MDA content decreased linearly with increasing RWC in both genotypes. Salinity-induced inhibition of photosynthesis in perennial ryegrass was mainly the result of stomatal limitation during early salt stress and metabolic limitation associated with the inhibition of RWC, activity of Rubisco, expression level of rbcL gene, and LSU under a prolonged period of severe salinity.

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Effect of exogenous application of sugars on the salt tolerance of perennial ryegrass protoplasts

Biologia ◽

10.2478/s11756-008-0033-z ◽

2008 ◽

Vol 63 (2) ◽

Cited By ~ 3

Author(s):

Hiroki Unno ◽

Yoshiyuki Maeda

Keyword(s):

Survival Rate ◽

Salt Tolerance ◽

Functional Groups ◽

Perennial Ryegrass ◽

Nacl Stress ◽

Nacl Solution ◽

Oh Groups ◽

Exogenous Application ◽

Young Leaves ◽

Activity Of Enzymes

AbstractVarious sugars were introduced by electroporation into perennial ryegrass protoplasts, and the involvement of intracellular functional groups of the sugars in salt tolerance was investigated. The protoplasts were prepared from the young leaves of perennial ryegrass, and those into which sugars were introduced were treated with NaCl solution (250 mM, pH 7.0) for 6 h at 10°C. The survival rate of the protoplasts increased when xylitol, cellobiose, 1-kestose, maltose, maltotriose, raffinose and trehalose were introduced, while no changes occurred when fructose, fucose, galactose, glucose, inositol, mannitol, mannose, rhamnose, sorbitol, sorbose, fructobiose, lactose and sucrose were introduced. Cellobiose, 1-kestose, maltose, maltotriose, raffinose and trehalose possess a number of equatorial OH (e-OH) groups that promote the structuration of H2O. Xylitol, however, structures H2O even though it does not possess the e-OH groups. Hence, it is suggested that under conditions of NaCl stress, structured H2O protects the structure of cell membranes and the activity of enzymes, and that e-OH groups are involved in enhancing salt tolerance.

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Arabidopsis heat shock transcription factor HSFA7b positively mediates salt stress tolerance by binding to an E-box-like motif to regulate gene expression

Journal of Experimental Botany ◽

10.1093/jxb/erz261 ◽

2019 ◽

Vol 70 (19) ◽

pp. 5355-5374 ◽

Cited By ~ 11

Author(s):

Dandan Zang ◽

Jingxin Wang ◽

Xin Zhang ◽

Zhujun Liu ◽

Yucheng Wang

Keyword(s):

Gene Expression ◽

Transcription Factors ◽

Heat Shock ◽

Salt Tolerance ◽

Stress Responses ◽

Ion Homeostasis ◽

Cellulose Synthase ◽

Regulate Gene Expression ◽

E Box ◽

Regulate Gene

Abstract Plant heat shock transcription factors (HSFs) are involved in heat and other abiotic stress responses. However, their functions in salt tolerance are little known. In this study, we characterized the function of a HSF from Arabidopsis, AtHSFA7b, in salt tolerance. AtHSFA7b is a nuclear protein with transactivation activity. ChIP-seq combined with an RNA-seq assay indicated that AtHSFA7b preferentially binds to a novel cis-acting element, termed the E-box-like motif, to regulate gene expression; it also binds to the heat shock element motif. Under salt conditions, AtHSFA7b regulates its target genes to mediate serial physiological changes, including maintaining cellular ion homeostasis, reducing water loss rate, decreasing reactive oxygen species accumulation, and adjusting osmotic potential, which ultimately leads to improved salt tolerance. Additionally, most cellulose synthase-like (CSL) and cellulose synthase (CESA) family genes were inhibited by AtHSFA7b; some of them were randomly selected for salt tolerance characterization, and they were mainly found to negatively modulate salt tolerance. By contrast, some transcription factors (TFs) were induced by AtHSFA7b; among them, we randomly identified six TFs that positively regulate salt tolerance. Thus, AtHSFA7b serves as a transactivator that positively mediates salinity tolerance mainly through binding to the E-box-like motif to regulate gene expression.

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A novel gene LbHLH from the halophyte Limonium bicolor enhances salt tolerance via reducing root hair development and enhancing osmotic resistance

BMC Plant Biology ◽

10.1186/s12870-021-03094-3 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Xi Wang ◽

Yingli Zhou ◽

Yanyu Xu ◽

Baoshan Wang ◽

Fang Yuan

Keyword(s):

Salt Tolerance ◽

Root Hair ◽

Salt Gland ◽

Nacl Stress ◽

35S Promoter ◽

Osmotic Resistance ◽

Salt Glands ◽

Limonium Bicolor ◽

Root Hair Development ◽

Hair Development

Abstract Background Identifying genes involved in salt tolerance in the recretohalophyte Limonium bicolor could facilitate the breeding of crops with enhanced salt tolerance. Here we cloned the previously uncharacterized gene LbHLH and explored its role in salt tolerance. Results The 2,067-bp open reading frame of LbHLH encodes a 688-amino-acid protein with a typical helix-loop-helix (HLH) domain. In situ hybridization showed that LbHLH is expressed in salt glands of L. bicolor. LbHLH localizes to the nucleus, and LbHLH is highly expressed during salt gland development and in response to NaCl treatment. To further explore its function, we heterologously expressed LbHLH in Arabidopsis thaliana under the 35S promoter. The overexpression lines showed significantly increased trichome number and reduced root hair number. LbHLH might interact with GLABRA1 to influence trichome and root hair development, as revealed by yeast two-hybrid analysis. The transgenic lines showed higher germination percentages and longer roots than the wild type under NaCl treatment. Analysis of seedlings grown on medium containing sorbitol with the same osmotic pressure as 100 mM NaCl demonstrated that overexpressing LbHLH enhanced osmotic resistance. Conclusion These results indicate that LbHLH enhances salt tolerance by reducing root hair development and enhancing osmotic resistance under NaCl stress.

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The full-length transcriptome of Spartina alterniflora reveals the complexity of high salt tolerance in monocotyledonous halophyte

10.1101/680819 ◽

2019 ◽

Cited By ~ 2

Author(s):

Wenbin Ye ◽

Taotao Wang ◽

Wei Wei ◽

Shuaitong Lou ◽

Faxiu Lan ◽

...

Keyword(s):

Gene Expression ◽

Salt Stress ◽

Alternative Splicing ◽

Salt Tolerance ◽

Protein Kinases ◽

Spartina Alterniflora ◽

High Salt ◽

Full Length ◽

Salt Tolerant ◽

High Salt Tolerance

ABSTRACTSpartina alterniflora (Spartina) is the only halophyte in the salt marsh. However, the molecular basis of its high salt tolerance remains elusive. In this study, we used PacBio full-length single molecule long-read sequencing and RNA-seq to elucidate the transcriptome dynamics of high salt tolerance in Spartina by salt-gradient experiments (0, 350, 500 and 800 mM NaCl). We systematically analyzed the gene expression diversity and deciphered possible roles of ion transporters, protein kinases and photosynthesis in salt tolerance. Moreover, the co-expression network analysis revealed several hub genes in salt stress regulatory networks, including protein kinases such as SaOST1, SaCIPK10 and three SaLRRs. Furthermore, high salt stress affected the gene expression of photosynthesis through down-regulation at the transcription level and alternative splicing at the post-transcriptional level. In addition, overexpression of two Spartina salt-tolerant genes SaHSP70-I and SaAF2 in Arabidopsis significantly promoted the salt tolerance of transgenic lines. Finally, we built the SAPacBio website for visualizing the full-length transcriptome sequences, transcription factors, ncRNAs, salt-tolerant genes, and alternative splicing events in Spartina. Overall, this study sheds light on the high salt tolerance mechanisms of monocotyledonous-halophyte and demonstrates the potential of Spartina genes for engineering salt-tolerant plants.

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Transcriptional reprogramming and enhanced photosynthesis drive inducible salt tolerance in sugarcane mutant line M4209

Journal of Experimental Botany ◽

10.1093/jxb/eraa339 ◽

2020 ◽

Vol 71 (19) ◽

pp. 6159-6173

Author(s):

Pooja Negi ◽

Manish Pandey ◽

Kevin M Dorn ◽

Ashok A Nikam ◽

Rachayya M Devarumath ◽

...

Keyword(s):

Salt Tolerance ◽

Redox Homeostasis ◽

Transcriptome Profiling ◽

Saccharum Officinarum ◽

Nacl Stress ◽

Mutant Line ◽

Cane Yield ◽

Leaf Biomass ◽

Transcriptional Reprogramming ◽

Radiation Induced

Abstract Sugarcane (Saccharum officinarum) is a globally cultivated cash crop whose yield is negatively affected by soil salinity. In this study, we investigated the molecular basis of inducible salt tolerance in M4209, a sugarcane mutant line generated through radiation-induced mutagenesis. Under salt-contaminated field conditions, M4209 exhibited 32% higher cane yield as compared with its salt-sensitive parent, Co86032. In pot experiments, post-sprouting phenotyping indicated that M4209 had significantly greater leaf biomass compared with Co86032 under treatment with 50 mM and 200 mM NaCl. This was concomitant with M4209 having 1.9-fold and 1.6-fold higher K+/Na+ ratios, and 4-fold and 40-fold higher glutathione reductase activities in 50 mM and 200 mM NaCl, respectively, which suggested that it had better ionic and redox homeostasis than Co86032. Transcriptome profiling using RNA-seq indicated an extensive reprograming of stress-responsive modules associated with photosynthesis, transmembrane transport, and metabolic processes in M4209 under 50 mM NaCl stress. Using ranking analysis, we identified Phenylalanine Ammonia Lyase (PAL), Acyl-Transferase Like (ATL), and Salt-Activated Transcriptional Activator (SATA) as the genes most associated with salt tolerance in M4209. M4209 also exhibited photosynthetic rates that were 3–4-fold higher than those of Co86032 under NaCl stress conditions. Our results highlight the significance of transcriptional reprogramming coupled with improved photosynthetic efficiency in determining salt tolerance in sugarcane.

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Submergence stress alters fructan and hormone metabolism and gene expression in perennial ryegrass with contrasting growth habits

Environmental and Experimental Botany ◽

10.1016/j.envexpbot.2020.104202 ◽

2020 ◽

Vol 179 ◽

pp. 104202

Author(s):

Xicheng Wang ◽

Manli Li ◽

Amber H. Jannasch ◽

Yiwei Jiang

Keyword(s):

Gene Expression ◽

Perennial Ryegrass ◽

Hormone Metabolism ◽

Submergence Stress ◽

Growth Habits

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Effects of NaCl stress on accumulation of K+, Na+, Cl-, NO3 -,sugar and proline contents in the seedlings of Triticale-I

Bangladesh Journal of Botany ◽

10.3329/bjb.v42i2.18019 ◽

2014 ◽

Vol 42 (2) ◽

pp. 189-194 ◽

Cited By ~ 1

Author(s):

Rifat Samad ◽

JL Karmoker

Keyword(s):

Salt Tolerance ◽

Fold Increase ◽

Nacl Stress ◽

Total Sugars ◽

Concomitant Decrease

NaCl stress at 50 - 150 mM NaCl caused a 12 - 16-fold increase in Na+ accumulation in the root and 3 - 10-fold in the shoot of Triticale-I with a concomitant decrease in that of K+ and Cl- . NaCl stress increased the accumulation of reducing, total sugars and proline both in the root and shoot of the seedlings. The mechanism of salt tolerance of Triticale-I plants with respect to ionic relation and accumulation of sugars and proline were discussed. DOI: http://dx.doi.org/10.3329/bjb.v42i2.18019 Bangladesh J. Bot. 42(2): 189-194, 2013 (December)

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Overexpression of Tamarix hispida ThTrx5 Confers Salt Tolerance to Arabidopsis by Activating Stress Response Signals

International Journal of Molecular Sciences ◽

10.3390/ijms21031165 ◽

2020 ◽

Vol 21 (3) ◽

pp. 1165

Author(s):

Jiayu Luan ◽

Jingxiang Dong ◽

Xin Song ◽

Jing Jiang ◽

Huiyu Li

Keyword(s):

Salt Stress ◽

Stress Response ◽

Salt Tolerance ◽

Germination Rate ◽

Nacl Stress ◽

Tamarix Hispida ◽

Resistant Varieties ◽

Transcriptome Comparison ◽

Plant Salt Tolerance ◽

Cellular Water

Salt stress inhibits normal plant growth and development by disrupting cellular water absorption and metabolism. Therefore, understanding plant salt tolerance mechanisms should provide a theoretical basis for developing salt-resistant varieties. Here, we cloned ThTrx5 from Tamarix hispida, a salt-resistant woody shrub, and generated ThTrx5-overexpressing transgenic Arabidopsis thaliana lines. Under NaCl stress, the germination rate of overexpressing ThTrx5 lines was significantly increased relative to that of the nontransgenic line; under salt stress, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and glutathione levels and root length and fresh weight values of transgenic ThTrx5 plants were significantly greater than corresponding values for wild-type plants. Moreover, with regard to the transcriptome, comparison of differential gene expression of transgenic versus nontransgenic lines at 0 h and 3 h of salt stress exposure revealed 500 and 194 differentially expressed genes (DEGs), respectively, that were mainly functionally linked to catalytic activity and binding process. Pull-down experiments showed that ThTrx bound 2-Cys peroxiredoxin BAS1-like protein that influences stress response-associated redox, hormone signal transduction, and transcription factor functions. Therefore, this work provides important insights into ThTrx5 mechanisms that promote salt tolerance in plants.

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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.

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