Salinity Stress Tolerance In Plants Research Articles

Signal crosstalk of phytomelatonin during salinity stress tolerance in plants

Signal crosstalk of phytomelatonin during salinity stress tolerance in plants

Allantoin improves salinity tolerance in Arabidopsis and rice through synergid activation of abscisic acid and brassinosteroid biosynthesis.

Soil salinity stress is one of the major bottlenecks for crop production. Although, allantoin is known to be involved in nitrogen metabolism in plants, yet several reports in recent time indicate its involvement in various abiotic stress responses including salinity stress. However, the detail mechanism of allantoin involvement in salinity stress tolerance in plants is not studied well. Moreover, we demonstrated the role of exogenous application of allantoin as well as increased concentration of endogenous allantoin in rendering salinity tolerance in rice and Arabidopsis respectively, via., induction of abscisic acid (ABA) and brassinosteroid (BR) biosynthesis pathways. Exogenous application of allantoin (10µM) provides salt-tolerance to salt-sensitive rice genotype (IR-29). Transcriptomic data after exogenous supplementation of allantoin under salinity stress showed induction of ABA (OsNCED1) and BR (Oscytochrome P450) biosynthesis genes in IR-29. Further, the key gene of allantoin biosynthesis pathway i.e., urate oxidase of the halophytic species Oryza coarctata was also found to induce ABA and BR biosynthesis genes when over-expressed in transgenic Arabidopsis. Thus, indicating that ABA and BR biosynthesis pathways were involved in allantoin mediated salinity tolerance in both rice and Arabidopsis. Additionally, it has been found that several physio-chemical parameters such as biomass, Na+/K+ ratio, MDA, soluble sugar, proline, allantoin and chlorophyll contents were also associated with the allantoin-mediated salinity tolerance in urate oxidase overexpressed lines of Arabidopsis. These findings depicted the functional conservation of allantoin for salinity tolerance in both plant clades.

Exogenous γ-aminobutyric acid (GABA) improves salt-inhibited nitrogen metabolism and the anaplerotic reaction of the tricarboxylic acid cycle by regulating GABA-shunt metabolism in maize seedlings

Salinity stress hampers the growth of most crop plants and reduces yield considerably. In addition to its role in metabolism, γ-aminobutyric acid (GABA) plays a special role in the regulation of salinity stress tolerance in plants, though the underlying physiological mechanism remains poorly understood. In order to study the physiological mechanism of GABA pathway regulated carbon and nitrogen metabolism and tis relationship with salt resistance of maize seedlings, we supplemented seedlings with exogenous GABA under salt stress. In this study, we showed that supplementation with 0.5 mmol·L−1 (0.052 mg·g−1) GABA alleviated salt toxicity in maize seedling leaves, ameliorated salt-induced oxidative stress, and increased antioxidant enzyme activity. Applying exogenous GABA maintained chloroplast structure and relieved chlorophyll degradation, thus improving the photosynthetic performance of the leaves. Due to the improvement in photosynthesis, sugar accumulation also increased. Endogenous GABA content and GABA transaminase (GABA-T) and succinate semialdehyde dehydrogenase (SSADH) activity were increased, while glutamate decarboxylase (GAD) activity was decreased, via the exogenous application of GABA under salt stress. Meanwhile, nitrogen metabolism and the tricarboxylic acid (TCA) cycle were activated by the supply of GABA. In general, through the regulation of GABA-shunt metabolism, GABA activated enzymes related to nitrogen metabolism and replenished the key substrates of the TCA cycle, thereby improving the balance of carbon and nitrogen metabolism of maize and improving salt tolerance.

Exogenous γ-aminobutyric acid (GABA) mitigated salinity-induced impairments in mungbean plants by regulating their nitrogen metabolism and antioxidant potential.

Increasing soil salinization has a detrimental effect on agricultural productivity.Therefore, strategies are needed to induce salinity-tolerance in crop species for sustainable foodproduction. γ-aminobutyric acid (GABA) plays a key role in regulating plant salinity stresstolerance. However, it remains largely unknown how mungbean plants (Vigna radiata L.) respondto exogenous GABA under salinity stress. Thus, we evaluated the effect of exogenous GABA (1.5 mM) on the growth and physiobiochemicalresponse mechanism of mungbean plants to saline stress (0-, 50-, and 100 mM [NaCland Na2SO4, at a 1:1 molar ratio]). Increased saline stress adversely affected mungbean plants' growth and metabolism. Forinstance, leaf-stem-root biomass (34- and 56%, 31- and 53%, and 27- and 56% under 50- and 100mM, respectively]) and chlorophyll concentrations declined. The carotenoid level increased (10%)at 50 mM and remained unaffected at 100 mM. Hydrogen peroxide (H2O2), malondialdehyde(MDA), osmolytes (soluble sugars, soluble proteins, proline), total phenolic content, andenzymatic activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase(POD), glutathione reductase (GTR), and polyphenol oxidation (PPO) were significantlyincreased. In leaves, salinity caused a significant increase in Na+ concentration but a decrease inK+ concentration, resulting in a low K+/Na+ concentration (51- and 71% under 50- and 100- mMstress). Additionally, nitrogen concentration and the activities of nitrate reductase (NR) andglutamine synthetase (GS) decreased significantly. The reduction in glutamate synthase (GOGAT)activity was only significant (65%) at 100 mM stress. Exogenous GABA decreased Na+, H2O2,and MDA concentrations but enhanced photosynthetic pigments, K+ and K+/Na+ ratio, Nmetabolism, osmolytes, and enzymatic antioxidant activities, thus reducing salinity-associatedstress damages, resulting in improved growth and biomass. Exogenous GABA may have improved the salinity tolerance of mungbean plants by maintaining their morpho-physiological responses and reducing the accumulation of harmfulsubstances under salinity. Future molecular studies can contribute to a better understanding of themolecular mechanisms by which GABA regulates mungbean salinity tolerance.

Understanding the physiological and molecular mechanism of salinity stress tolerance in plants

Salinity is considered a global threat to agriculture and causes a significant reduction in crop yield. In particular, salinity stress promotes reactive oxygen species (ROS) accumulation and ionic imbalance in cells, leading to oxidative stress and even cell death. A large number of genes which are involved in defense, hormone, carbohydrate and metabolic pathways are down-regulated under salinity stress. Plants respond to salinity stress through a series of physiological and molecular mechanisms including antioxidant enzymes, hormones, defense related genes and signaling pathway activation. Plant defense systems modulate the overproduction of ROS through the activation of stress responsive-genes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and glutamine synthetase (GS) and transcription factors such as MYBs, WRKY, and ERF. The salt overly sensitive (SOS) pathway is potentially involved in salt stress tolerance. SOS1, SOS3 and SOS2 are required for the oxidative stress tolerance by reducing the uptakes, and inter-cellular and intra-cellular distribution of Na+ and Cl−. This review discusses the discovery of stress-responsive genes and signaling pathways, and summarizes the research progress on the regulatory mechanisms of salinity stress tolerance in plants, which will help accelerate breeding programs for salinity stress tolerance.

SALINITY STRESS EFFECTS ON PLANTS AND USE OF RHIZOBACTERIA: A REVIEW

Soil salinity is being recognized as a major threat to the agriculture and food production in the arid and semi-arid regions of the world. Accumulation of various salts creates osmotic imbalance and ionic toxicity in plants and makes crop production difficult. Plant system has developed certain adaptation strategies for tolerating the toxicity of the salts. The present review focuses on the various effects of salinity stress on physiological and biochemical aspects of plants and the role of rhizobacteria to mitigate the harmful effects of salinity stress. Induction of toxicity mechanism of salinity stress tolerance in plants along with the strategies needed to be adapted to make sustainable agriculture.

Recent Progress on Melatonin-Induced Salinity Tolerance in Plants: An Overview

In this context, it is necessary to select and develop salt-tolerant genotypes that can grow in salty soils and have high yields, and formulate strategies which may enhance the plant survival under salinity stress. Melatonin (N-acetyl-5-methoxytryptamine) is an important biological hormone that provides resistance to abiotic stress conditions and can be secreted by plants. Melatonin concentration in plants varies depending on genotype, temperature and growth period. Increase in melatonin concentration is associated with increased SNAT and HIOMAT/ASMT enzyme activity. It plays an important role in gibberellic acid and abscisic acid biosynthesis during the germination and provides plant growth and development. Exogenous application of melatonin significantly alleviates chlorophyll degradation and stomatal closure caused by salt stress, improves photosynthesis and enhances plants' salt tolerance. Besides it significantly reduces the harmful effects of salinity by regulating plant physiology, improving plant morphology, photosynthesis and activities of antioxidant enzymes. The present review discusses the recent studies on the effect of melatonin on plant growth and physiology against salt stress that have important impacts on plant growth and development have been given according to the findings of various researches. It also highlights the mechanim/s of melatonin-induced salinity stress tolerance in plants.

Heterologous expression of ZmNF-YA12 confers tolerance to drought and salt stress in Arabidopsis

Drought and salinity are serious environmental factors limiting the growth and productivity of plants worldwide. Therefore, it is necessary to develop ways to improve drought and salinity stress tolerance in plants. In this study, a drought-responsive nuclear factor Y subunit A gene, ZmNF-YA12, was cloned from maize. qPCR revealed ZmNF-YA12 transcript in all vegetative and reproductive tissues, with higher levels in young roots. Expression analyses of maize revealed that ZmNF-YA12 was induced by abscisic acid (ABA), jasmonic acid (JA), and abiotic stresses, including dehydration, high salinity, cold, and polyethylene glycol (PEG) treatment. The heterologous expression of ZmNF-YA12 in Arabidopsis plants resulted in increased root length and better plant growth than in wild-type (WT) plants under conditions of mannitol, salt, and JA stress on 1/2 MS medium. Transgenic Arabidopsis showed improved tolerance to drought and salt stresses in soil, and higher proline content and lower malondialdehyde (MDA) content than WT controls. The transgenic plants also maintained higher peroxidase (POD) activities than WT plants under conditions of NaCl stress. A yeast two-hybrid experiment demonstrated that ZmNF-YA12 interacted with ZmNF-YC1 and ZmNF-YC15. Moreover, the transcript levels of stress-responsive genes (RD29A, RD29B, RAB18, and RD22) were markedly increased in transgenic lines under conditions of drought and salt stress. These observations suggested that the ZmNF-YA12 gene may confers drought and salt stress tolerance by regulating stress-related genes or interacting with ZmNF-YC1 and ZmNF-YC15, and has potential applications in molecular breeding with maintenance of production under conditions of stress.

Glyoxalase III enhances salinity tolerance through reactive oxygen species scavenging and reduced glycation.

Methylglyoxal (MG) is a metabolically generated highly cytotoxic compound that accumulates in all living organisms, from Escherichia coli to humans, under stress conditions. To detoxify MG, nature has evolved reduced glutathione (GSH)-dependent glyoxalase and NADPH-dependent aldo-keto reductase systems. But both GSH and NADPH have been reported to be limiting in plants under stress conditions, and thus detoxification might not be performed efficiently. Recently, glyoxalase III (GLY III)-like enzyme activity has been reported from various species, which can detoxify MG without any cofactor. In the present study, we have tested whether an E. coli gene, hchA, encoding a functional GLY III, could provide abiotic stress tolerance to living systems. Overexpression of this gene showed improved tolerance in E. coli and Saccharomyces cerevisiae cells against salinity, dicarbonyl, and oxidative stresses. Ectopic expression of the E. coli GLY III gene (EcGLY-III) in transgenic tobacco plants confers tolerance against salinity at both seedling and reproductive stages as indicated by their height, weight, membrane stability index, and total yield potential. Transgenic plants showed significantly increased glyoxalase and antioxidant enzyme activity that resisted the accumulation of excess MG and reactive oxygen species (ROS) during stress. Moreover, transgenic plants showed more anti-glycation activity to inhibit the formation of advanced glycation end product (AGE) that might prevent transgenic plants from stress-induced senescence. Taken together, all these observations indicate that overexpression of EcGLYIII confers salinity stress tolerance in plants and should be explored further for the generation of stress-tolerant plants.

Molecular Insights into the Role of Reactive Oxygen, Nitrogen and Sulphur Species in Conferring Salinity Stress Tolerance in Plants

Molecular Insights into the Role of Reactive Oxygen, Nitrogen and Sulphur Species in Conferring Salinity Stress Tolerance in Plants

Phosphoinositides: Emerging players in plant salinity stress tolerance

Soil salinity reduces the biodiversity of natural ecosystems and severely limits sustainability and profitability of agricultural production systems. Given the increasing reliance of modern agriculture on irrigation ( Liu et al., 2020a Liu M.M. Pan T. Allakhyerdiev S.I. Yu M. Shabala S. Crop halophytism: an environmentally sustainable solution for global food security. Trends Plant Sci. 2020; 25: 630-634 Abstract Full Text Full Text PDF PubMed Scopus (32) Google Scholar ), the extent of the soil salinity is only going to increase under current climate trends scenarios. In this context, achieving global food security in the 21st century will be not feasible without developing a salt-tolerant crop germplasm. However, the physiological and genetic complexity of this trait has significantly handicapped progress in the field.

Crucial Cell Signaling Compounds Crosstalk and Integrative Multi-Omics Techniques for Salinity Stress Tolerance in Plants.

In the era of rapid climate change, abiotic stresses are the primary cause for yield gap in major agricultural crops. Among them, salinity is considered a calamitous stress due to its global distribution and consequences. Salinity affects plant processes and growth by imposing osmotic stress and destroys ionic and redox signaling. It also affects phytohormone homeostasis, which leads to oxidative stress and eventually imbalances metabolic activity. In this situation, signaling compound crosstalk such as gasotransmitters [nitric oxide (NO), hydrogen sulfide (H2S), hydrogen peroxide (H2O2), calcium (Ca), reactive oxygen species (ROS)] and plant growth regulators (auxin, ethylene, abscisic acid, and salicylic acid) have a decisive role in regulating plant stress signaling and administer unfavorable circumstances including salinity stress. Moreover, recent significant progress in omics techniques (transcriptomics, genomics, proteomics, and metabolomics) have helped to reinforce the deep understanding of molecular insight in multiple stress tolerance. Currently, there is very little information on gasotransmitters and plant growth regulator crosstalk and inadequacy of information regarding the integration of multi-omics technology during salinity stress. Therefore, there is an urgent need to understand the crucial cell signaling crosstalk mechanisms and integrative multi-omics techniques to provide a more direct approach for salinity stress tolerance. To address the above-mentioned words, this review covers the common mechanisms of signaling compounds and role of different signaling crosstalk under salinity stress tolerance. Thereafter, we mention the integration of different omics technology and compile recent information with respect to salinity stress tolerance.

Transcriptome Analysis of Arabidopsis thaliana Plants Treated with a New Compound Natolen128, Enhancing Salt Stress Tolerance.

Salinity stress is a major threat to agriculture and global food security. Chemical priming is a promising approach to improving salinity stress tolerance in plants. To identify small molecules with the capacity to enhance salinity stress tolerance in plants, chemical screening was performed using Arabidopsis thaliana. We screened 6400 compounds from the Nagoya University Institute of Transformative Bio-Molecule (ITbM) chemical library and identified one compound, Natolen128, that enhanced salinity-stress tolerance. Furthermore, we isolated a negative compound of Natolen128, namely Necolen124, that did not enhance salinity stress tolerance, though it has a similar chemical structure to Natolen128. We conducted a transcriptomic analysis of Natolen128 and Necolen124 to investigate how Natolen128 enhances high-salinity stress tolerance. Our data indicated that the expression levels of 330 genes were upregulated by Natolen128 treatment compared with that of Necolen124. Treatment with Natolen128 increased expression of hypoxia-responsive genes including ethylene biosynthetic enzymes and PHYTOGLOBIN, which modulate accumulation of nitric oxide (NO) level. NO was slightly increased in plants treated with Natolen128. These results suggest that Natolen128 may regulate NO accumulation and thus, improve salinity stress tolerance in A. thaliana.

Enhancers as potential targets for engineering salinity stress tolerance in crop plants.

Enhancers represent noncoding regulatory regions of the genome located distantly from their target genes. They regulate gene expression programs in a context-specific manner via interacting with promoters of one or more target genes and are generally associated with transcription factor binding sites and epi(genomic)/chromatin features, such as regions of chromatin accessibility and histone modifications. The enhancers are difficult to identify due to the modularity of their associated features. Although enhancers have been studied extensively in human and animals, only a handful of them has been identified in few plant species till date due to nonavailability of plant-specific experimental and computational approaches for their discovery. Being an important regulatory component of the genome, enhancers represent potential targets for engineering agronomic traits, including salinity stress tolerance in plants. Here, we provide a review of the available experimental and computational approaches along with the associated sequence and chromatin/epigenetic features for the discovery of enhancers in plants. In addition, we provide insights into the challenges and future prospects of enhancer research in plant biology with emphasis on potential applications in engineering salinity stress tolerance in crop plants.

Salt stress in Arabidopsis thaliana seedlings: Role of indoleamines in stress alleviation

Salinity is a major environmental stress in agriculture with significantly detrimental effects on crop productivity. The development of strategies to enhance salinity stress tolerance in plants is essential to ensure crop production in saline environments. Melatonin (Mel) and serotonin (Ser) accumulate in response to environmental stresses and are presumed to play protective roles and improve growth of tissues during recovery. In this study, the effects of Mel and Ser were investigated in Arabidopsis under NaCl stress. Exogenous Mel (10 µM) and Ser (10 µM) treatment significantly increased fresh weight, lateral root number, and shoot height in A. thaliana seedlings exposed to NaCl stress (25 mM and 50 mM) compared to the non-treated control seedlings. In order to understand the role of these indoleamines in alleviating salt stress, we investigated the effects of Mel and Ser treatments on the expression of salt stress responsive genes including, transcription factors involved in abscisic acid (ABA) signaling pathway, ABA-INSENSITIVE 3 (ABI3)and ABA-INSENSITIVE 5 (ABI5); ABA responsive gene, RESPONSIVE TO DESSICATION 29B (RD29B), ABA-independent gene, RESPONSIVE TO DESSICATION 29A (RD29A) and Arabidopsis trithorax-like gene (ATX1) which function in stress responses via ABA-dependent and ABA-independent manner. Other genes included, ROS-signaling transcription factor ZAT10 and ZAT12, and the genes encoding ion transporters crucial for maintaining ion homeostasis, HIGH AFFINITY K+ TRANSPORTER 5 (HAK5) and SALT OVERLY SENSITIVE 1 (SOS1). Mel (10 µM) pre-treatment for 24 hrs followed by 50 mM salt treatment up-regulated ABI3, RD29B, ZAT12 and HAK5. The Ser (10 µM) pre-treatment significantly up-regulated ZAT12.These results indicate that indoleamine pre-treatment improved plant growth under salt stress with Mel facilitating salt tolerance via upregulation of ABA responsive genes, mediation of antioxidant defense systems to counteract the salt-induced ROS overproduction as well as controlling ion homeostasis. Although Ser displayed no significant effects on ABA signaling, it was found to increase the expression of antioxidant defense gene, ZAT12. This study demonstrates the importance of indoleamine pathway in mediation of salt stress response and provides the first indication of the involvement of Ser in salt stress tolerance.

The key roles of salicylic acid and sulfur in plant salinity stress tolerance

The salinization of agriculture soils over the globe has become one of the most devastating stresses and is significantly limiting cultivated land area, and crop productivity and quality. It is very imperative to explore both salinity tolerance in plants and insights into approaches (and underlying mechanisms) for effectively controlling salinity impacts. To this end, the role of phytohormone salicylic acid (SA) and plant nutrient sulfur (S) in promoting salinity tolerance has been researched in isolated studies, and SA–S interaction results have been little discussed. Given this, taking into account recent literature on SA, S and soil salinity, this paper aimed to (i) overview of the major impacts of soil salinity on plant health; (ii) highlight the significance of SA and S in improving plant salinity tolerance; (iii) discuss the role and underlying mechanism of SA, S and their interaction in the modulation of plant growth and development under salinity stress; and also to (iv) appraise the discussed literature and enlighten the major prospects.

Comparative transcriptome profiling of rice colonized with beneficial endophyte, Piriformospora indica, under high salinity environment.

The salinity stress tolerance in plants has been studied enormously, reflecting its agronomic relevance. Despite the extensive research, limited success has been achieved in relation to the plant tolerance mechanism. The beneficial interaction between Piriformospora indica and rice could essentially improve the performance of the plant during salt stress. In this study, the transcriptomic data between P. indica treated and untreated rice roots were compared under control and salt stress conditions. Overall, 661 salt-responsive differentially expressed genes (DEGs) were detected with 161 up- and 500 down-regulated genes in all comparison groups. Gene ontology analyses indicated the DEGs were mainly enriched in "auxin-activated signaling pathway", "water channel activity", "integral component of plasma membrane", "stress responses", and "metabolic processes". Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that the DEGs were primarily related to "Zeatin biosynthesis", "Fatty acid elongation", "Carotenoid biosynthesis", and "Biosynthesis of secondary metabolites". Particularly, genes related to cell wall modifying enzymes (e.g. invertase/pectin methylesterase inhibitor protein and arabinogalactans), phytohormones (e.g. Auxin-responsive Aux/IAA gene family, ent-kaurene synthase, and 12-oxophytodienoate reductase) and receptor-like kinases (e.g. AGC kinase and receptor protein kinase) were induced in P. indica colonized rice under salt stress condition. The differential expression of these genes implies that the coordination between hormonal crosstalk, signaling, and cell wall dynamics contributes to the higher growth and tolerance in P. indica-inoculated rice. Our results offer a valuable resource for future functional studies on salt-responsive genes that should improve the resilience and adaptation of rice against salt stress.

Ethylene: A Master Regulator of Salinity Stress Tolerance in Plants.

Salinity stress is one of the major threats to agricultural productivity across the globe. Research in the past three decades, therefore, has focused on analyzing the effects of salinity stress on the plants. Evidence gathered over the years supports the role of ethylene as a key regulator of salinity stress tolerance in plants. This gaseous plant hormone regulates many vital cellular processes starting from seed germination to photosynthesis for maintaining the plants’ growth and yield under salinity stress. Ethylene modulates salinity stress responses largely via maintaining the homeostasis of Na+/K+, nutrients, and reactive oxygen species (ROS) by inducing antioxidant defense in addition to elevating the assimilation of nitrates and sulfates. Moreover, a cross-talk of ethylene signaling with other phytohormones has also been observed, which collectively regulate the salinity stress responses in plants. The present review provides a comprehensive update on the prospects of ethylene signaling and its cross-talk with other phytohormones to regulate salinity stress tolerance in plants.

Zn2+dependent glyoxalase I plays the major role in methylglyoxal detoxification and salinity stress tolerance in plants.

Glyoxalase pathway is the major pathway of methylglyoxal detoxification and is ubiquitously present in all organisms ranging from prokaryotes to eukaryotes. Glyoxalase I (GLYI) and Glyoxalase II (GLYII), the two core enzymes of this pathway work together to neutralize methylglyoxal (MG), a dicarbonyl molecule with detrimental cytotoxicity at higher concentrations. The first step towards the detoxification of MG is catalyzed by GLYI, a metalloenzyme that requires divalent metal ions (either Zn2+ as seen in eukaryotes or Ni2+ as in prokaryotes). However, both Zn2+ and Ni2+ dependent GLYIs have been shown to co-exist in a higher eukaryote i.e. Arabidopsis thaliana. In the present study, we determine the role of both Zn2+ dependent (AtGLYI2) and Ni2+ dependent (AtGLYI3, AtGLYI6) GLYIs from Arabidopsis in salinity stress tolerance. AtGLYI2 overexpressing Arabidopsis plants showed better growth rate while maintaining lower levels of MG under high saline conditions. They were taller with more number of silique formation with respect to their Ni2+ dependent counterparts. Further, lack in germination of Arabidopsis AtGLYI2 mutants in presence of exogenous MG indicates the direct involvement of Zn2+ dependent GLYI in MG detoxification, suggesting Zn2+ dependent GLYI as the main enzyme responsible for MG detoxification and salinity stress tolerance.

Emerging investigator series: molecular mechanisms of plant salinity stress tolerance improvement by seed priming with cerium oxide nanoparticles

Engineered nanomaterials interfaced with plant seeds can improve stress tolerance during the vulnerable seedling stage.