Salt Tolerance Of Seedlings Research Articles

Exogenous Melatonin Promotes the Salt Tolerance by Removing Active Oxygen and Maintaining Ion Balance in Wheat (Triticum aestivum L.).

Melatonin (MT) is a small molecule indole hormone that plays an important role in the regulation of biological processes and abiotic stress resistance. Previous studies have confirmed that MT promotes the normal development of plants under stress by mediating physiological regulation mechanisms. However, the physiological mechanism of exogenous MT regulating seed germination and seedling growth of wheat under salt stress is still unclear. In this study, NaCl stress decreased germination rate and inhibited seedling growth of wheat, but shoot length, root length, and plant weight of SM15 did not change significantly. The addition of 300 μM MT in the cultivation solution directly promoted the germination rate of SM15 and ZM18, and lateral root production, but decreased the germination rate of JM22 and inhibited the length of germ and radicle of three varieties under salt stress. For wheat seedling, application of MT could increase proline content, soluble protein, soluble sugar, Ca2+ content, and vital amino acid content in leaves to keep high water content, low level of H2O2 content, and low [K+]/[Na+] ratio. MT increased root vigor and [K+]/[Na+] ratio and decreased H2O2 content in root induced by salt stress. In conclusion, MT enhanced salt tolerance in wheat seeds and seedlings by regulating the synthesis of soluble protein and sugar, ion compartmentation in roots and leaves, enhancement of enzymatic systems, and changes in amino acid levels. Salt resistance varied with different varieties under the same environmental condition. SM15 was a higher salt-resistant variety and JM22 was a salt-sensitive one. In wheat production, the application of exogenous MT should consider the differences among varieties of wheat during the sowing and seedling stages.

Cationic modified lignin: Regulation of synthetic microspheres for achieving anti-photolysis and sustained release of the abscisic acid

Lignin is an abundant, renewable natural resource that shows UV resistance and whose amphiphilicity can be modified, which means that it could potentially encapsulate photo-sensitive agrichemicals. However, current technical lignins, e.g., alkaline lignin (AL), tend to form large aggregates, which severely limits its encapsulation performance. In this study, three cationic surfactants were selected for hydrophobic modification of AL, and to produce AL microspheres (AL-MPs) encapsulating abscisic acid (ABA). The surfactants tested were dodecyl tetramethyl ammonium bromide DTAB (single C12 chain), dimethyl behenyl ammonium bromide DDAB (two C12 chains) and cetylpyridinium chloride CPC (single C16 chain). The particle sizes, zeta-potentials, and encapsulation efficiencies of the AL-MPs were modified by changing the type of the surfactant and the weight percentage (wt%) of AL. The range of particle sizes, zeta potentials and encapsulation efficiencies were 232–1226 nm, –56.1–18.7 mV, and 62–78%, respectively. Fourier transform infrared spectroscopy (FTIR) was used to characterize the MPs. The photolysis protection and release of ABA from ABA-loaded MPs (e.g., ABA@AL-DDAB) were studied and a release kinetics model was built to probe the release behaviour. The effects of ABA@AL-MPs on the salt tolerance of rice seedlings under salinity stress were studied, and the mechanism is discussed. ABA@AL-MPs effectively protected the seedlings from growth inhibition by salinity stress. ABA@AL-DDAB was the most effective formulation, outperforming ABA@AL-CTAB and even the no-salt control. DDAB is less cytotoxic than CTAB and has the potential, when combine with lignin to encapsulate ABA and other agrichemicals to produce formulations with photolysis resistance and sustained-release properties.

Experimental evidence from Suaeda glauca explains why the species is not naturally distributed in non-saline soils

Euhalophytes are not naturally distributed in non-saline areas. However, the reason for this is unclear. Seed germination, seedling emergence and plant tolerance to salt were evaluated in the euhalophyte Suaeda glauca. One population occurs in saline soils (SS), and another has been cultivated in non-saline soils (NSS) for more than 20 years. A total of 500 mM NaCl had a greater adverse effect on seed germination and seedling emergence of brown seeds in S. glauca from NSS compared with those from SS. The seedlings grown from brown seeds collected from NSS were uniform and dwarf, but this was not the case for the seedlings from SS. The salt tolerance of seedlings from NSS did not significantly differ from those from SS, as judged by such factors as the shoot dry weight and contents of leaf Na+ and K+. The concentrations of phytohormones, such as abscisic acid, methyl jasmonate, gibberellin 3 and 4, zeatin riboside, brassinolide, indole acetic acid, and indole-3-propionic acid, in the leaves of seedlings from NSS were generally lower than those from SS under different concentrations of NaCl. In conclusion, salts are not strictly required for the growth of S. glauca. The reason why typical euhalophytes, such as S. glauca, are not found in non-saline areas is probably because the seedlings grown in NSS become dwarf and uniform, thus, weakening their ability to compete with glycophytes in non-saline habitats.

Seed osmopriming with Ca2+ and K+ improves salt tolerance in quinoa seeds and seedlings by amplifying antioxidant defense and ameliorating the osmotic adjustment process.

Salinity restricts seed germination and seedling growth through induction ofosmotic and oxidative stresses. Therefore, this study aimed to enhance salinity tolerance in quinoa seed by pre-optimized osmo-priming treatments of CaCl2 (10mM, 10°C, 10h) and KNO3 (150mM, 5°C, 24h). The results showed that these treatments developed the cellular defense mechanisms in seeds as 'priming memory' that could improve the physiological and biochemical responses to salinity in post-priming stages. The germination capacity and seedling growth decreased with increasing salinity that was accompanied with a higher content of MDA and H2O2. However, the improvement of primed seed vigor against high salinity was explained by increasing the biological defense mechanisms including antioxidant enzymes (CAT, APX, SOD, GPX and PPO) and antioxidant metabolites (DPPH antioxidant activity, phenolics, flavonoids, ascorbic acid), particularly in presence of salt stress. In addition, Ca2+ and K+ priming acquired salinity tolerance in post-priming stages through a significant increase in the accumulation of proline, glycine-betaine, soluble carbohydrate. Improvement in homeostasis of K+/Na+ ratio by promoting K+ maintenance and Na+ exclusion was also found in post-priming stages. These observations may be utilized as effective methods in improving salinity tolerance of quinoa seed germination in saline agriculture by improving the antioxidant system, osmolyte accumulation and mineral nutrient homeostasis.

Integrated application of plant growth promoting rhizobacteria and biochar improves salt tolerance in eggplant seedlings

A pot study was conducted to determine the effects of the combination of plant growth promoting rhizobacteria (PGPR) and biochar on the growth, physiological, and biochemical characteristics of eggplant seedlings under salinity stress. The greenhouse experiment included two salinity levels of NaCl [S0 (0 mM NaCl) and S1 (100 mM NaCl)], three biochar levels [B0 (non-biochar), B1 (5%) and B2 (10%)] and two PGPR [R0 (non-PGPR), R1 (combination of Bacillus megaterium TV-6D, Paenibacillus polymyxa KIN- 37, and Pantoea agglomerans RK92). Results showed that plant growth, relative leaf water content (LRWC), and chlorophyll content of eggplant seedlings decreased significantly, while malondialdehyde (MDA), hydrogen peroxide (H2O2), proline, sucrose and ABA content, and electrolyte leakage (EL) increased significantly with increase in salinity levels. Biochar and PGPR applications mitigated the negative influence of salinity stress on plant growth and physiological and biochemical characteristics of eggplant seedlings, enhancing chlorophyll content, plant nutrient element uptake, and antioxidant enzyme activity. The enhanced salinity tolerance due to biochar and PGPR applications could be associated with a significant reduction in Na and Cl uptake, MDA, H2O2 and EL and an increase in LRWC, chlorophyll content, antioxidant activity and plant nutrient element uptake. Therefore, it can be concluded that combining biochar and PGPR could be used to minimize the detrimental impacts of salinity stress conditions in eggplant seedlings.

Transcriptome analysis reveals the main metabolic pathway of c-GMP induced by salt stress in tomato (Solanum lycopersicum) seedlings.

Tomato (Solanum lycopersicum L.) is a model crop as well as an important food worldwide. In arid areas, increasing soil salinity has limited higher yields in tomato production. As a second messenger molecule, cyclic guanosine monophosphate (c-GMP) plays an indispensable role in plant response to salt stress by regulating cell processes to promote plant growth and development. However, this mechanism has not been fully explored in tomato seedlings. In this experiment, tomato seeds were cultured in four treatments: (1) distilled water (CK); (2) 20μM c-GMP (T1); (3) 50mM NaCl (T2); and (4) 20μM c-GMP+50mM NaCl (T3). The results show that 20μM c-GMP effectively alleviated the inhibitory effect of 50mM NaCl on growth and development, and induced the expression of 1580 differentially expressed genes (DEGs). Seedlings in the CK vs T1 shared 95 upregulated and 442 downregulated DEGs, whereas T2 vs T3 shared 271 upregulated and 772 downregulated DEGs. Based on KEGG (Kyoto Encyclopaedia of Genes and Genomes) analysis, the majority of DEGs were involved in metabolism; exogenous c-GMP induced significant enrichment of pathways associated with carbohydrates, phenylpropanoids and fatty acid metabolism. Most PMEs , acCoA , PAL , PODs , FADs , and AD were upregulated, and GAPDHs , PL , PG , BXL4 , and β-G were downregulated, which reduced susceptibility of tomato seedlings to salt and promoted their salt tolerance. The application of c-GMP increased soluble sugar, flavonoid and lignin contents, reduced accumulation of malondialdehyde (MDA), and enhanced the activity of peroxidase (POD). Thus, our results provide insights into the molecular mechanisms associated with salt tolerance of tomato seedlings.

Genome-Wide Analysis of the Soybean Calmodulin-Binding Protein 60 Family and Identification of GmCBP60A-1 Responses to Drought and Salt Stresses.

Calmodulin-binding protein 60 (CBP60) members constitute a plant-specific protein family that plays an important role in plant growth and development. In the soybean genome, nineteen CBP60 members were identified and analyzed for their corresponding sequences and structures to explore their functions. Among GmCBP60A-1, which primarily locates in the cytomembrane, was significantly induced by drought and salt stresses. The overexpression of GmCBP60A-1 enhanced drought and salt tolerance in Arabidopsis, which showed better state in the germination of seeds and the root growth of seedlings. In the soybean hairy roots experiment, the overexpression of GmCBP60A-1 increased proline content, lowered water loss rate and malondialdehyde (MDA) content, all of which likely enhanced the drought and salt tolerance of soybean seedlings. Under stress conditions, drought and salt response-related genes showed significant differences in expression in hairy root soybean plants of GmCBP60A-1-overexpressing and hairy root soybean plants of RNAi. The present study identified GmCBP60A-1 as an important gene in response to salt and drought stresses based on the functional analysis of this gene and its potential underlying mechanisms in soybean stress-tolerance.

Evolutionary Relationships and Divergence of KNOTTED1-Like Family Genes Involved in Salt Tolerance and Development in Cotton (Gossypium hirsutum L.).

The KNOX (KNOTTED1-like homeobox) transcription factors play an important role in leaf, shoot apical meristem and seed development and respond to biotic and abiotic stresses. In this study, we analyzed the diversity and evolutionary history of the KNOX gene family in the genome of tetraploid cotton (Gossypium hirsutum). Forty-four putative KNOX genes were identified. All KNOX genes from seven higher plant species were classified into KNOXI, KNOXII, and KNATM clades based on a phylogenetic analysis. Chromosomal localization and collinearity analysis suggested that whole-genome duplication and a polyploidization event contributed to the expansion of the cotton KNOX gene family. Analyses of expression profiles revealed that the GhKNOX genes likely responded to diverse stresses and were involved in cotton growth developmental processes. Silencing of GhKNOX2 enhanced the salt tolerance of cotton seedlings, whereas silencing of GhKNOX10 and GhKNOX14 reduced seedling tolerance to salt stress. Silencing of GhSTM3 influenced the cotton flowering time and plant development. These findings clarify the evolution of the cotton KNOX gene family and provide a foundation for future functional studies of KNOX proteins in cotton growth and development and response to abiotic stresses.

An endoplasmic reticulum–localized cytochrome b5 regulates high-affinity K+ transport in response to salt stress in rice

Potassium (K+) is an essential element for growth and development in both animals and plants, while high levels of environmental sodium (Na+) represent a threat to most plants. The uptake of K+ from high-saline environments is an essential mechanism to maintain intracellular K+/Na+ homeostasis, which can help reduce toxicity caused by Na+ accumulation, thereby improving the salt tolerance of plants. However, the mechanisms and regulation of K+-uptake during salt stress remain poorly understood. In this study, we identified an endoplasmic reticulum-localized cytochrome b5 (OsCYB5-2) that interacted with a high-affinity K+ transporter (OsHAK21) at the plasma membrane. The association of OsCYB5-2 with the OsHAK21 transporter caused an increase in transporter activity by enhancing the apparent affinity for K+-binding but not Na+-binding. Heme binding to OsCYB5-2 was essential for the regulation of OsHAK21. High salinity directly triggered the OsHAK21-OsCYB5-2 interaction, promoting OsHAK21-mediated K+-uptake and restricting Na+ entry into cells; this maintained intracellular K+/Na+ homeostasis in rice cells. Finally, overexpression of OsCYB5-2 increased OsHAK21-mediated K+ transport and improved salt tolerance in rice seedlings. This study revealed a posttranslational regulatory mechanism for HAK transporter activity mediated by a cytochrome b5 and highlighted the coordinated action of two proteins to perceive Na+ in response to salt stress.

Genome-Wide Analysis of the Cytochrome P450 Gene Family Involved in Salt Tolerance in Gossypium hirsutum.

Plant cytochrome P450 (P450) participates in a wide range of biosynthetic reactions and targets a variety of biological molecules. These reactions lead to various fatty acid conjugates, plant hormones, secondary metabolites, lignin, and various defensive compounds. In our previous research, transcriptome analysis was performed on the salt-tolerant upland cotton “Tongyan No. 1.” Many differentially expressed genes (DEGs) belong to the P450 family, and their domains occur widely in plants. In this current research, P450 genes were identified in Gossypium hirsutum with the aid of bioinformatics methods for investigating phylogenetic relations, gene structure, cis-elements, chromosomal localization, and collinearity within a genome. qRT-PCR was conducted to analyze P450 gene expression patterns under salt stress. The molecular weights of the 156 P450 genes were in the range of 5,949.6–245,576.3 Da, and the length of the encoded amino acids for all the identified P450 genes ranged from 51 to 2,144. P450 proteins are divided into four different subfamilies based on phylogenetic relationship, gene structure, and chromosomal localization of gene replication. The length of P450 genes in upland cotton differs greatly, ranging from 1,500 to 13,000 bp. The number of exons in the P450 family genes ranged from 1 to 9, while the number of introns ranged from 0 to 8, and there were similar trends within clusters. A total of 31 cis-acting elements were identified by analyzing 1,500 bp promoter sequences. Differences were found in cis-acting elements among genes. The consistency between qRT-PCR and previous transcriptome analysis of salt tolerance DEGs indicated that they were likely to be involved in the salt tolerance of cotton seedlings. Our results provide valuable information on the evolutionary relationships of genes and functional characteristics of the gene family, which is beneficial for further study of the cotton P450 gene family.

Genome-Wide Association Study for Detecting Salt-Tolerance Loci and Candidate Genes in Rice

Salinity is one of the major constraints causing soil problems and is considered a limitation to increased rice production in rice-growing countries. This genome-wide association study (GWAS) experiment was conducted to understand the genetic basis of salt tolerance at the seedling stage in Korean rice. After 10 days of salt stress treatment, salt tolerance was evaluated with a standard evaluation system using a visual salt injury score. With 191 Korean landrace accessions and their genotypes, including 266,040 single-nucleotide polymorphisms (SNPs), using a KNU Axiom Oryza 580K Genotyping Array, GWAS was conducted to detect three QTLs with significant SNPs with a −log10(P) threshold of ≥3.66. The QTL of qSIS2, showed −log10(P) = 3.80 and the lead SNP explained 7.87% of total phenotypic variation. The QTL of qSIS4, showed −log10(P) = 4.05 and the lead SNP explained 10.53% of total phenotypic variation. The QTL of qSIS8 showed −log10(P) = 3.78 and the lead SNP explained 7.83% of total phenotypic variation. Among the annotated genes located in these three QTL regions, five genes were selected as candidates (Os04g0481600, Os04g0485300, Os04g0493000, Os04g0493300, and Os08g0390200) for salt tolerance in rice seedlings based on the gene expression database and their previously known functions.

MiR169q and NUCLEAR FACTOR YA8 enhance salt tolerance by activating PEROXIDASE1 expression in response to ROS

Salt stress significantly reduces the productivity of crop plants including maize (Zea mays). miRNAs are major regulators of plant growth and stress responses, but few studies have examined the potential impacts of miRNAs on salt stress responses in maize. Here, we show that ZmmiR169q is responsive to stress-induced ROS signals. After detecting that salt stress and exogenous H2O2 treatment reduced the accumulation of ZmmiR169q, stress assays with transgenic materials showed that depleting ZmmiR169q increased seedling salt tolerance whereas overexpressing ZmmiR169q decreased salt tolerance. Helping explain these observations, we found that ZmmiR169q repressed the transcript abundance of its target NUCLEAR FACTOR YA8 (ZmNF-YA8), and overexpression of ZmNF-YA8 in maize improved salt tolerance, specifically by transcriptionally activating the expression of the efficient antioxidant enzyme PEROXIDASE1. Our study reveals a direct functional link between salt stress and a miR169q-NF-YA8 regulatory module that plants use to manage ROS stress and strongly suggests that ZmNF-YA8 can be harnessed as a resource for developing salt-tolerant crop varieties.

Growth and physiological responses of ectomycorrhizal Coccoloba uvifera (L.) L. seedlings to salt stress

We studied the effect of the ectomycorrhizal (ECM) fungus Scleroderma bermudense on growth, photosynthesis and transpiration rates, chlorophyll fluorescence and content, K/Na and Ca/Na homeostasis, and water status of two provenances of Coccoloba uvifera L. (named also seagrape) seedlings exposed to four levels of salinity (0.0, 54.7, 164.1 and 273.5 mM NaCl equivalent to 0.02, 5, 15 and 25 dS m−1, respectively). The results indicated that S. bermudense improved the salt tolerance in seagrape seedlings. There were no differences in terms of growth performance, nutritional and physiological functions between the two ECM seagrape provenances in response to salt stress. The reduction of the Na concentration and the increase of K and Ca favored a higher K/Na and Ca/Na ratio, respectively, in the tissues of the ECM seedlings. Furthermore, the beneficial effects of ECM symbiosis on the photosynthetic and transpiration rates, chlorophyll fluorescence and content, stomatal conductance and water status resulted in the improved growth performance of the seagrape provenances exposed to salt stress. From an ecological point of view, seagrape in symbiosis with S. bermudense may be used in the development of ornamental plantings and coastal windbreaks along beaches and roadsides in Cuba.

A novel raffinose biological pathway is observed by symbionts of cotton≡Verticillium dahliae to improve salt tolerance genetically on cotton

AbstractVerticillium dahliae is a soil‐borne, phytopathogenic fungus that causes Verticillium wilt in cotton. Salt tolerance of cotton plants suffering from Verticillium wilt was significantly improved, but the mechanism is unknown. In this study, we built a symbiont named Cotton≡VD by immersing cotton plant roots into Verticillium dahliae liquid for four days. This resulted in a strong interaction between hyphae and the cotton roots. Under NaCl treatment for 24 h, the Cotton≡VD displayed less leaf wilting and improved root growth compared with the control. Biochemical tests of SOD, POD and CAT showed significant overexpression in Cotton≡VD compared with CK. RNA‐seq data analysis of Cotton≡VD indicated a novel ‘galactose metabolism pathway’ in the KEGG database, in which two key genes, GolS2 and RFS5, were significantly differentially expressed. Symbiotic metabolites inositol galactosyl could be transformed into raffinose to scavenge free radicals and participate in plant osmotic regulation to alleviate salt stress in Cotton≡VD. Functional analysis indicated that silencing of the target gene GhRFS (RFS5) led to a decrease of raffinose content and salt tolerance as compared with CK. Cotton≡VD can significantly improve cotton seedling salt tolerance through improving raffinose content, providing new insights into the salt tolerance mechanism and new salt‐tolerant material in the future.

Silicon as mitigator of salt stress in mango tree seedlings

The use of saline water dramatically reduces the growth and development of plants. Thus, salt stress mitigation can be important to allow the use of this water in the agriculture. This study aimed to evaluate the effect of silicon as attenuators of effects caused by salt stress on seedlings of “Espada” mango tree variety. An experiment was conducted under completely randomized experimental design in a factorial scheme (5 x 2). The factors studied consisted of silicon concentrations (0, 50, 100, 150 and 200 mg L-1) and irrigation with low water (0.8 dS m-1) and high (6 dS m-1) electrical conductivity and the growth of mango tree seedlings was assessed 70 days after sowing (DAS) by the height, number of leaves, stem diameter, dry matter of root, aerial part and total, dry matter content, Dickson Quality Index and Index of tolerance to salinity. The application of silicon via leaf mitigates the deleterious effects of salt stress in mango seedlings. Silicon 200 mg L-1 promotes higher growth, dry matter accumulation and 100 mg L-1 concentration provides higher salt tolerance in mango seedlings. Electrical conductivity in the irrigation water at 6 dS m-1 reduce the growth and quality the of mango tree seedlings

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

BackgroundAs 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.ResultsSalt 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).ConclusionsOur 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.

QTL Mapping and Expression Analysis of Candidate Genes for Salt and Drought Tolerance in Corchorus capsularis Seedlings

QTL Mapping and Expression Analysis of Candidate Genes for Salt and Drought Tolerance in Corchorus capsularis Seedlings

GWAS and WGCNA uncover hub genes controlling salt tolerance in maize (Zea mays L.) seedlings.

Two hub genes GRMZM2G075104 and GRMZM2G333183 involved in salt tolerance were identified by GWAS and WGCNA. Furthermore, they were verified to affect salt tolerance by candidate gene association analysis. Salt stress influences maize growth and development. To decode the genetic basis and hub genes controlling salt tolerance is a meaningful exploration for cultivating salt-tolerant maize varieties. Herein, we used an association panel consisting of 305 lines to identify the genetic loci responsible for Na+- and K+-related traits in maize seedlings. Under the salt stress, seven significant single nucleotide polymorphisms were identified using a genome-wide association study, and 120 genes were obtained by scanning the linkage disequilibrium regions of these loci. According to the transcriptome data of the above 120 genes under salinity treatment, we conducted a weighted gene co-expression network analysis. Combined the gene annotations, two SNaC/SKC (shoot Na+ content/shoot K+ content)-associated genes GRMZM2G075104 and GRMZM2G333183 were finally identified as the hub genes involved in salt tolerance. Subsequently, these two genes were verified to affect salt tolerance of maize seedlings by candidate gene association analysis. Haplotypes TTGTCCG-CT and CTT were determined as favorable/salt-tolerance haplotypes for GRMZM2G075104 and GRMZM2G333183, respectively. These findings provide novel insights into genetic architectures underlying maize salt tolerance and contribute to the cultivation of salt-tolerant varieties in maize.

Melatonin Improves Cotton Salt Tolerance by Regulating ROS Scavenging System and Ca2 + Signal Transduction.

As one of the cash crops, cotton is facing the threat of abiotic stress during its growth and development. It has been reported that melatonin is involved in plant defense against salt stress, but whether melatonin can improve cotton salt tolerance and its molecular mechanism remain unclear. We investigated the role of melatonin in cotton salt tolerance by silencing melatonin synthesis gene and exogenous melatonin application in upland cotton. In this study, applicating of melatonin can improve salt tolerance of cotton seedlings. The content of endogenous melatonin was different in cotton varieties with different salt tolerance. The inhibition of melatonin biosynthesis related genes and endogenous melatonin content in cotton resulted in the decrease of antioxidant enzyme activity, Ca2+ content and salt tolerance of cotton. To explore the protective mechanism of exogenous melatonin against salt stress by RNA-seq analysis. Melatonin played an important role in the resistance of cotton to salt stress, improved the salt tolerance of cotton by regulating antioxidant enzymes, transcription factors, plant hormones, signal molecules and Ca2+ signal transduction. This study proposed a regulatory network for melatonin to regulate cotton’s response to salt stress, which provided a theoretical basis for improving cotton’s salt tolerance.

Integrated transcriptomics and metabolomics analysis to characterize alkali stress responses in canola (Brassica napus L.)

BackgroundSoil salinization is a major constraint limiting agricultural development and affecting crop growth and productivity, especially in arid and semi-arid regions. Understanding the molecular mechanism of the adaptability of canola to salt stress is very important to improve the salt tolerance of canola and promote its cultivation in saline alkali soil. ResultsTo identify the metabolomic and transcriptomic mechanisms of canola under alkaline salt stress, we collected roots of control (no salt treatment) and 72 h Na2CO3-stressed canola seedlings (hydroponics) for metabolic profiling of metabolites, supplemented with RNA-Seq analysis and real-time quantitative PCR validation. Metabolomic analysis showed that the metabolites of amino acids and fatty acids were higher accumulated under alkaline salt stress, including L-proline, L-glutamate, L-histidine, L-phenylalanine, L-citrulline, L-tyrosine, L-saccharopine, L-tryptophan, linoleic acid, dihomo gamma linolenic acid, alpha linolenic acid, Eric acid, oleic acid and neuronic acid, while the metabolism of carbohydrate (sucrase, alpha, alpha trehalose), polyol (ribitol), UDP-D-galactose, D-mannose, D-fructose and D-glucose 6-phosphate decreased. Transcriptomic and metabolomic pathway analysis indicated that carbohydrate metabolism may not play an important role in the resistance of canola to alkaline salt stress. Organic acid metabolism (fatty acid accumulation) and amino acid metabolism are important metabolic pathways in the root of canola under alkaline salt stress. ConclusionsThese results suggest that the genes and metabolites involved in fatty acid metabolism and amino acids metabolism in roots of canola may regulate salt tolerance of canola seedlings under alkaline salt stress, which improves our understanding of the molecular mechanisms of salt tolerance in canola.