Exogenous melatonin improves the salt tolerance of cotton by removing active oxygen and protecting photosynthetic organs

Abstract Background As damage to the ecological environment continues to increase amid unreasonable amounts of irrigation, soil salinization has become a major challenge to agricultural development. Melatonin (MT) is a pleiotropic signal molecule and indole hormone, which alleviates the damage of abiotic stress to plants. MT has been confirmed to eliminate reactive oxygen species (ROS) by improving the antioxidant system and reducing oxidative damage under adversity. However, the mechanism by which exogenous MT mediates salt tolerance by regulating the photosynthetic capacity and ion balance of cotton seedlings still remains unknown. In this study, the regulatory effects of MT on the photosynthetic system, osmotic modulators, chloroplast, and anatomical structure of cotton seedlings were determined under 0–500 μM MT treatments with salt stress induced by treatment with 150 mM NaCl. Results Salt stress reduces the chlorophyll content, net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate, PSII photochemical efficiency, PSII actual photochemical quantum yield, the apparent electron transfer efficiency, stomata opening, and biomass. In addition, it increases non-photochemical quenching. All of these responses were effectively alleviated by exogenous treatment with MT. Exogenous MT reduces oxidative damage and lipid peroxidation by reducing salt-induced ROS and protects the plasma membrane from oxidative toxicity. MT also reduces the osmotic pressure by reducing the salt-induced accumulation of Na+ and increasing the contents of K+ and proline. Exogenous MT can facilitate stomatal opening and protect the integrity of cotton chloroplast grana lamella structure and mitochondria under salt stress, protect the photosynthetic system of plants, and improve their biomass. An anatomical analysis of leaves and stems showed that MT can improve xylem and phloem and other properties and aides in the transportation of water, inorganic salts, and organic substances. Therefore, the application of MT attenuates salt-induced stress damage to plants. Treatment with exogenous MT positively increased the salt tolerance of cotton seedlings by improving their photosynthetic capacity, stomatal characteristics, ion balance, osmotic substance biosynthetic pathways, and chloroplast and anatomical structures (xylem vessels and phloem vessels). Conclusions Our study attributes help to protect the structural stability of photosynthetic organs and increase the amount of material accumulation, thereby reducing salt-induced secondary stress. The mechanisms of MT-induced plant tolerance to salt stress provide a theoretical basis for the use of MT to alleviate salt stress caused by unreasonable irrigation, fertilization, and climate change.

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Comparative physiological and full-length transcriptome analyses reveal the molecular mechanism of melatonin-mediated salt tolerance in okra (Abelmoschus esculentus L.)

BMC Plant Biology ◽

10.1186/s12870-021-02957-z ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Yihua Zhan ◽

Tingting Wu ◽

Xuan Zhao ◽

Zhanqi Wang ◽

Yue Chen

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Molecular Mechanism ◽

Stress Responses ◽

Sulfur Metabolism ◽

Protective Role ◽

Full Length ◽

Abelmoschus Esculentus ◽

Plant Tolerance ◽

Signal Molecule

Abstract Background Melatonin, a multifunctional signal molecule, has been reported to play crucial roles in growth and development and stress responses in various plant species. Okra (Abelmoschus esculentus L.) is a food crop with extremely high values of nutrition and healthcare. Recent reports have revealed the protective role of melatonin in alleviating salt stress. However, little is known about its regulatory mechanisms in response to salt stress in okra. Results In this study, we explored whether exogenous melatonin pretreatment could alleviate salt stress (300 mM NaCl) of okra plants. Results showed that exogenous application of melatonin (50 μM) significantly enhanced plant tolerance to salt stress, as demonstrated by the plant resistant phenotype, as well as by the higher levels of the net photosynthetic rate, chlorophyll fluorescence and chlorophyll content in comparison with nontreated salt-stressed plants. Additionally, melatonin pretreatment remarkably decreased the levels of lipid peroxidation and H2O2 content and scavenged O2•- in melatonin-pretreated plants, which may be attributed to the higher levels of enzyme activities including POD and GR. Moreover, a combination of third- (PacBio) and second-generation (Illumina) sequencing technologies was applied to sequence full-length transcriptomes of okra. A total of 121,360 unigenes was obtained, and the size of transcript lengths ranged from 500 to 6000 bp. Illumina RNA-seq analysis showed that: Comparing with control, 1776, 1063 and 1074 differential expression genes (DEGs) were identified from the three treatments (NaCl, MT50 and MT + NaCl, respectively). These genes were enriched in more than 10 GO terms and 34 KEGG pathways. Nitrogen metabolism, sulfur metabolism, and alanine, aspartate and glutamate metabolism were significantly enriched in all three treatments. Many transcription factors including MYB, WRKY, NAC etc., were also identified as DEGs. Conclusions Our preliminary results suggested that melatonin pretreatment enhanced salt tolerance of okra plants for the first time. These data provide the first set of full-length isoforms in okra and more comprehensive insights into the molecular mechanism of melatonin responses to salt stress.

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Thymol improves salinity tolerance of tobacco by increasing the Na+ efflux and enhancing the content of NO and GSH

10.21203/rs.3.rs-745750/v2 ◽

2021 ◽

Author(s):

liang xu ◽

Jia-Qian Song ◽

yuelin wang ◽

Xiao-Han Liu ◽

Xue-Li Li ◽

...

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Root Growth ◽

Abiotic Stresses ◽

Nature Medicine ◽

Oxygen Species ◽

Plant Tolerance ◽

Ros Accumulation ◽

Na Efflux ◽

The Stability

Abstract Plants have evolved a lot of strategies to improve salt tolerance to cope with salt stress. Recent studies have suggested that thymol (a nature medicine) enhances the plant tolerance against abiotic stresses, but the mechanisms are rarely known. Here, we found that thymol played an important role in maintaining root growth under salt stress. Thymol rescued root growth from salt stress via ameliorating ROS (reactive oxygen species) accumulation, lipid peroxidation, and cell death. In addition, thymol enhanced the level of NO (nitric oxide) and GSH (glutathione) to repress ROS accumulation, further protecting the stability of cell membrane. Thymol-induced Na+ efflux in roots and leaves under salt stress may depend on the upregulation of SOS1, HKT1 and NHX1. Consequently, all of these evidences suggested that thymol improved tobacco salt tolerance via enhancing NO and GSH content as well as inducing Na+ efflux.

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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.

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Light energy dissipation in Quercus ilex resprouts after fire

Functional Plant Biology ◽

10.1071/pp99073 ◽

2000 ◽

Vol 27 (2) ◽

pp. 129 ◽

Cited By ~ 4

Author(s):

Isabel Fleck ◽

Xavier Aranda ◽

Bouchra El Omari ◽

Jon Permanyer ◽

Anunciación Abadía ◽

...

Keyword(s):

Energy Dissipation ◽

Quercus Ilex ◽

Photosynthetic Capacity ◽

Leaf Age ◽

Photochemical Efficiency ◽

Photosynthetic Apparatus ◽

High Irradiance ◽

Light Energy ◽

Photochemical Quenching ◽

Sink Strength

Holm oak (Quercus ilex) plants that have resprouted after fire have higher photosynthetic capacity than control plants in intact vegetation. In this study, branches detached from forest plants were fed with dithiothreitol (DTT) in the laboratory to inhibit zeaxanthin production and thus reduce the dissipation of light energy as heat. This allowed us to test the hypothesis that plants with greater photosynthetic capacity, and therefore greater photo-chemical sink strength, would suffer a lower reduction in photochemical efficiency under stressful conditions. Greater rates of photochemistry in resprouts, which exhibited increased photosynthesis (A), leaf conductance (g), quantum yield of PSII (ΔF/Fm′) and photochemical quenching (qP), were related to lower non-radiative dissipation of excess energy as indicated by 1 – (Fv′/Fm′). However, the fraction of energy remaining of that used in photo-chemistry or dissipated thermally in the PSII antennae was similar in resprouts and controls and was not affected by DTT, especially under high irradiance conditions. Zeaxanthin involvement in PSII protection operated in resprouts and controls since DTT induced the same kind of response (NPQ decrease) but was lower in resprouts. These chloro-phyll fluorescence results suggest the participation of some additional mechanism for energy dissipation. Light capture characteristics of the photosynthetic apparatus did not differ between resprouts and controls, and leaf age did not play a determining role in the differences observed.

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Thymol improves salinity tolerance of tobacco by increasing the Na + efflux and enhancing the content of NO and GSH

10.21203/rs.3.rs-745750/v1 ◽

2021 ◽

Author(s):

liang xu ◽

Jia-Qian Song ◽

yuelin wang ◽

Xiao-Han Liu ◽

Xue-Li Li ◽

...

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Root Growth ◽

Abiotic Stresses ◽

Nature Medicine ◽

Oxygen Species ◽

Plant Tolerance ◽

Ros Accumulation ◽

Na Efflux ◽

The Stability

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Overexpression of 2-Cys Prx increased salt tolerance of photosystem Ⅱ(PSⅡ) in tobacco

10.7287/peerj.preprints.2500v1 ◽

2016 ◽

Cited By ~ 2

Author(s):

Hui-hui Zhang ◽

Nan Xu ◽

Xin Li ◽

Si-yu Gu

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Complex Function ◽

Photochemical Efficiency ◽

Active Oxygen ◽

Gene Overexpression ◽

Sod Activity ◽

Tobacco Leaves ◽

Acceptor Side ◽

Donor And Acceptor

To explore the plant active oxygen scavenging and photosynthesis function of 2-Cys Prx, a newly discovered member of the antioxidant protease family, the tobacco 2-Cys Prx gene was cloned into the plant expression vector prok Ⅱ. This vector, which is controlled by the constitutive strong promoter CaMV35S, was introduced into tobacco by Agrobacteria-mediated transformation. The 816-bp open reading frame of tobacco 2-Cys Prx encodes 271 amino acids and showed high homology with 2-Cys Prx genes from Solanum lycopersicum, Vitis vinifera, and Populus trichocarpa, indicating 2-Cys Prx gene is highly conserved. The active oxygen metabolism and chlorophyll fluorescence response to salt stress were also studied. Under salt stress, superoxide dismutase (SOD) activity in tobacco leaves increased, while ascorbate peroxidase (APX) activity decreased. Additionally, the donor- and acceptor-side function of photosystem Ⅱ (PSⅡ) were affected by salt stress to different degrees, with the latter significantly more affected than the former. The H2O2 and malondialdehyde content of 2-Cys Prx-overexpression tobacco leaves under salt stress were all significantly lower than those of wild-type (CK) leaves. The PSⅡ maximum photochemical efficiency (Fv/Fm) and the performance index on absorption basis (PIABS) of 2-Cys Prx-overexpression leaves were significantly lower than those of CK leaves under salt stress. Various relative fluorescence intensities of the 2-Cys Prx-overexpression plants exhibited significantly lower increases in amplitude than those of CK plants. Thus, 2-Cys Prx increased the salt tolerance of PSⅡ function and lowered the PSⅡ light inhibition effect in plants under salt stress, suggesting that 2-Cys Prx gene overexpression can alleviate H2O2 buildup and lower the peroxide levels of cytomembrane lipids under salt stress. Thus, 2-Cys Prx gene overexpression can protect oxygen-evolving complex function at the donor side of PSⅡ under salt stress and also improve electron transfer at the acceptor side of PSⅡ.

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Overexpression of Peroxidase Gene GsPRX9 Confers Salt Tolerance in Soybean

International Journal of Molecular Sciences ◽

10.3390/ijms20153745 ◽

2019 ◽

Vol 20 (15) ◽

pp. 3745 ◽

Cited By ~ 4

Author(s):

Ting Jin ◽

Yangyang Sun ◽

Ranran Zhao ◽

Zhong Shan ◽

Junyi Gai ◽

...

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Glycine Soja ◽

Primary Root ◽

Wild Soybean ◽

Plant Tolerance ◽

Salt Tolerant ◽

Fresh Weight ◽

Peroxidase Gene

Peroxidases play prominent roles in antioxidant responses and stress tolerance in plants; however, their functions in soybean tolerance to salt stress remain unclear. Here, we investigated the role of a peroxidase gene from the wild soybean (Glycine soja), GsPRX9, in soybean tolerance to salt stress. GsPRX9 gene expression was induced by salt treatment in the roots of both salt-tolerant and -sensitive soybean varieties, and its relative expression level in the roots of salt-tolerant soybean varieties showed a significantly higher increase than in salt-sensitive varieties after NaCl treatment, suggesting its possible role in soybean response to salt stress. GsPRX9-overexpressing yeast (strains of INVSc1 and G19) grew better than the control under salt and H2O2 stress, and GsPRX9-overexpressing soybean composite plants showed higher shoot fresh weight and leaf relative water content than control plants after NaCl treatment. Moreover, the GsPRX9-overexpressing soybean hairy roots had higher root fresh weight, primary root length, activities of peroxidase and superoxide dismutase, and glutathione level, but lower H2O2 content than those in control roots under salt stress. These findings suggest that the overexpression of the GsPRX9 gene enhanced the salt tolerance and antioxidant response in soybean. This study would provide new insights into the role of peroxidase in plant tolerance to salt stress.

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Choline-Mediated Lipid Reprogramming as a Dominant Salt Tolerance Mechanism in Grass Species Lacking Glycine Betaine

Plant and Cell Physiology ◽

10.1093/pcp/pcaa116 ◽

2020 ◽

Author(s):

Kun Zhang ◽

Weiting Lyu ◽

Yanli Gao ◽

Xiaxiang Zhang ◽

Yan Sun ◽

...

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Glycine Betaine ◽

Metabolic Pathways ◽

Poa Pratensis ◽

Choline Chloride ◽

Photochemical Efficiency ◽

Kentucky Bluegrass ◽

Grass Species ◽

Tolerance Mechanism

Abstract Choline, as a precursor of glycine betaine (GB) and phospholipids, is known to play roles in plant tolerance to salt stress, but the downstream metabolic pathways regulated by choline conferring salt tolerance are still unclear for non-GB-accumulating species. The objectives were to examine how choline affects salt tolerance in a non-GB-accumulating grass species and to determine major metabolic pathways of choline regulating salt tolerance involving GB or lipid metabolism. Kentucky bluegrass (Poa pratensis) plants were subjected to salt stress (100 mM NaCl) with or without foliar application of choline chloride (1 mM) in a growth chamber. Choline or GB alone and the combined application increased leaf photochemical efficiency, relative water content and osmotic adjustment and reduced leaf electrolyte leakage. Choline application had no effects on the endogenous GB content and GB synthesis genes did not show responses to choline under nonstress and salt stress conditions. GB was not detected in Kentucky bluegrass leaves. Lipidomic analysis revealed an increase in the content of monogalactosyl diacylglycerol, phosphatidylcholine and phosphatidylethanolamine and a decrease in the phosphatidic acid content by choline application in plants exposed to salt stress. Choline-mediated lipid reprogramming could function as a dominant salt tolerance mechanism in non-GB-accumulating grass species.

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Selenium and Salt Interactions in Black Gram (Vigna mungo L): Ion Uptake, Antioxidant Defense System, and Photochemistry Efficiency

Plants ◽

10.3390/plants9040467 ◽

2020 ◽

Vol 9 (4) ◽

pp. 467 ◽

Cited By ~ 3

Author(s):

Muhammad Jawad Hassan ◽

Muhammad Ali Raza ◽

Imran Khan ◽

Tehseen Ahmad Meraj ◽

Mukhtar Ahmed ◽

...

Keyword(s):

Salt Stress ◽

Oxidative Damage ◽

Antioxidant Defense ◽

Low Dose ◽

Reducing Sugars ◽

Photochemical Efficiency ◽

Vigna Mungo ◽

Black Gram ◽

Ps Ii ◽

Na Uptake

Salinity is a major abiotic stress which limits crop production, especially under rainfed conditions. Selenium (Se), as an important micronutrient, plays a vital role in mitigating detrimental effects of different abiotic stresses. The objective of this research was to examine the effect of Se fertilization on black gram (Vigna mungo) under salt stress. Our results showed that salt stress (100 mM NaCl) in leaves significantly induced oxidative damage and caused a decline in relative water content, chlorophyll (Chl), stomatal conductance (gs), photochemical efficiency (Fv/Fm), sucrose, and reducing sugars. A low dose of Se (1.5 ppm) significantly reduced hydrogen peroxide content, malondialdehyde formation, cell membrane damage, and also improved antioxidative enzyme activities, including superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, and glutathione peroxidase under salt stress. Se-treated plants exhibited higher Chl, gs, Fv/Fm, sucrose, and reducing sugars than untreated plants in response to salt stress. In addition, Se application enhanced Se uptake and reduced Na+ uptake, but Cl− remained unaffected. Our results indicated that a low dose of Se effectively alleviated salt damage via inhibition of Na+ uptake and enhanced antioxidant defense resulting in a significant decrease in oxidative damage, and maintained gaseous exchange and PS II function for sucrose and reducing sugars accumulation in black gram.

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