Alleviation of Salt Stress and Changes in Glycyrrhizic Acid Accumulation by Dark Septate Endophytes in Glycyrrhiza glabra Grown under Salt Stress.

This study aimed to investigate the mechanisms by which dark septate endophytes (DSE) regulate salt tolerance and the accumulation of bioactive constituents in licorice. First, the salt stress tolerance and resynthesis with the plant effect of isolated DSE from wild licorice were tested. Second, the performance of licorice inoculated with DSE, which had the best salt-tolerant and growth-promoting effects, was examined under salt stress. All isolated DSE showed salt tolerance and promoted plant growth, withCurvularia lunata D43 being the most effective. Under salt stress, C. lunata D43 could promote growth, increase antioxidant enzyme activities, enhance glycyrrhizic acid accumulation, improve key enzyme activities in the glycyrrhizic acid synthesis pathway, and induce the expression of the key enzyme gene and salt tolerance gene of licorice. The structural equation model demonstrated that DSE alleviate the negative effects of salt stress through direct and indirect pathways. Variations in key enzyme activities, gene expression, and bioactive constituent concentration can be attributed to the effects of DSE. These results contribute to revealing the value of DSE for cultivating medicinal plants in saline soils.

Salt stress amelioration and nutrient strengthening in spinach (Spinacia oleracea L.) via biochar amendment and zinc fortification: seed priming versus foliar application.

Soil salinity is a major nutritional challenge with poor agriculture production characterized by high sodium (Na+) ions in the soil. Zinc oxide nanoparticles (ZnO NPs) and biochar have received attention as a sustainable strategy to reduce biotic and abiotic stress. However, there is a lack of information regarding the incorporation of ZnO NPs with biochar to ameliorate the salinity stress (0, 50,100 mM). Therefore, the current study aimed to investigate the potentials of ZnO NPs application (priming and foliar) alone and with a combination of biochar on the growth and nutrient availability of spinach plants under salinity stress. Results demonstrated that salinity stress at a higher rate (100 mM) showed maximum growth retardation by inducing oxidative stress, resulted in reduced photosynthetic rate and nutrient availability. ZnO NPs (priming and foliar) alone enhanced growth, chlorophyll contents and gas exchange parameters by improving the antioxidant enzymes activity of spinach under salinity stress. While, a significant and more pronounced effect was observed at combined treatments of ZnO NPs with biochar amendment. More importantly, ZnO NPs foliar application with biochar significantly reduced the Na+ contents in root 57.69%, and leaves 61.27% of spinach as compared to the respective control. Furthermore, higher nutrient contents were also found at the combined treatment of ZnO NPs foliar application with biochar. Overall, ZnO NPs combined application with biochar proved to be an efficient and sustainable strategy to alleviate salinity stress and improve crop nutritional quality under salinity stress. We inferred that ZnO NPs foliar application with a combination of biochar is more effectual in improving crop nutritional status and salinity mitigation than priming treatments with a combination of biochar.

Salt-tolerant plant growth-promoting bacteria as a versatile tool for combating salt stress in crop plants.

Soil salinization poses a great threat to global agricultural ecosystems, and finding ways to improve the soils affected by salt and maintain soil health and sustainable productivity has become a major challenge. Various physical, chemical and biological approaches are being evaluated to address this escalating environmental issue. Among them, fully utilizing salt-tolerant plant growth-promoting bacteria (PGPB) has been labeled as a potential strategy to alleviate salt stress, since they can not only adapt well to saline soil environments but also enhance soil fertility and plant development under saline conditions. In the last few years, an increasing number of salt-tolerant PGPB have been excavated from specific ecological niches, and various mechanisms mediated by such bacterial strains, including but not limited to siderophore production, nitrogen fixation, enhanced nutrient availability, and phytohormone modulation, have been intensively studied to develop microbial inoculants in agriculture. This review outlines the positive impacts and growth-promoting mechanisms of a variety of salt-tolerant PGPB and opens up new avenues to commercialize cultivable microbes and reduce the detrimental impacts of salt stress on plant growth. Furthermore, considering the practical limitations of salt-tolerant PGPB in the implementation and potential integration of advanced biological techniques in salt-tolerant PGPB to enhance their effectiveness in promoting sustainable agriculture under salt stress are also accentuated.

Salt stress alters the cell wall components and structure in Miscanthus sinensis stems.

Miscanthus is a perennial grass suitable for the production of lignocellulosic biomass on marginal lands. The effects of salt stress on Miscanthus cell wall composition and its consequences on biomass quality have nonetheless received relatively little attention. In this study, we investigated how exposure to moderate (100 mM NaCl) or severe (200 mM NaCl) saline growing conditions altered the composition of both primary and secondary cell wall components in the stems of 15 Miscanthus sinensis genotypes. The exposure to stress drastically impacted biomass yield and cell wall composition in terms of content and structural features. In general, the observed compositional changes were more pronounced under severe stress conditions and were more apparent in genotypes with a higher sensitivity towards stress. Besides a severely reduced cellulose content, salt stress led to increased pectin content, presumably in the form of highly branched rhamnogalacturonan type I. Although salt stress had a limited effect on the total lignin content, the acid-soluble lignin content was strongly increased in the most sensitive genotypes. This effect was also reflected in substantially altered lignin structures and led to a markedly reduced incorporation of syringyl subunits and p-coumaric acid moieties. Interestingly, plants that were allowed a recovery period after stress ultimately had a reduced lignin content compared to those continuously grown under control conditions. In addition, the salt stress-induced cell wall alterations contributed to an improved enzymatic saccharification efficiency.

Differential gene expression of salt-tolerant alfalfa in response to salinity and inoculation by Ensifer meliloti.

BACKGROUND: Alfalfa (Medicago sativa L.) experiences many negative effects under salinity stress, which may be mediated by recurrent selection. Salt-tolerant alfalfa may display unique adaptations in association with rhizobium under salt stress. RESULTS: To elucidate inoculation effects on salt-tolerant alfalfa under salt stress, this study leveraged a salt-tolerant alfalfa population selected through two cycles of recurrent selection under high salt stress. After experiencing 120-day salt stress, mRNA was extracted from 8 random genotypes either grown in 0 or 8 dS/m salt stress with or without inoculation by Ensifer meliloti. Results showed 320 and 176 differentially expressed genes (DEGs) modulated in response to salinity stress or inoculation x salinity stress, respectively. Notable results in plants under 8 dS/m stress included upregulation of a key gene involved in the Target of Rapamycin (TOR) signaling pathway with a concomitant decrease in expression of the SNrK pathway. Inoculation of salt-stressed plants stimulated increased transcription of a sulfate-uptake gene as well as upregulation of the Lysine-27-trimethyltransferase (EZH2), Histone 3 (H3), and argonaute (AGO, a component of miRISC silencing complexes) genes related to epigenetic and post-transcriptional gene control. CONCLUSIONS: Salt-tolerant alfalfa may benefit from improved activity of TOR and decreased activity of SNrK1 in salt stress, while inoculation by rhizobiumstimulates production of sulfate uptake- and other unique genes.

Automated Imaging to Evaluate the Exogenous Gibberellin (Ga3) Impact on Seedlings from Salt-Stressed Lettuce Seeds.

Salinity stress is a common challenge in plant growth, impacting seed quality, germination, and general plant health. Sodium chloride (NaCl) ions disrupt membranes, causing ion leakage and reducing seed viability. Gibberellic acid (GA3) treatments have been found to promote germination and mitigate salinity stress on germination and plant growth. 'Bauer' and 'Muir' lettuce (Lactuca sativa) seeds were soaked in distilled water (control), 100 mM NaCl, 100 mM NaCl + 50 mg/L GA3, and 100 mM NaCl + 150 mg/L GA3 in Petri dishes and kept in a dark growth chamber at 25 °C for 24 h. After germination, seedlings were monitored using embedded cameras, capturing red, green, and blue (RGB) images from seeding to final harvest. Despite consistent germination rates, 'Bauer' seeds treated with NaCl showed reduced germination. Surprisingly, the 'Muir' cultivar's final dry weight differed across treatments, with the NaCl and high GA3 concentration combination yielding the poorest results (p < 0.05). This study highlights the efficacy of GA3 applications in improving germination rates. However, at elevated concentrations, it induced excessive hypocotyl elongation and pale seedlings, posing challenges for two-dimensional imaging. Nonetheless, a sigmoidal regression model using projected canopy size accurately predicted dry weight across growth stages and cultivars, emphasizing its reliability despite treatment variations (R2 = 0.96, RMSE = 0.11, p < 0.001).

Screening for genetic variability in photosynthetic regulation provides insights into salt performance traits in forage sorghum under salt stress.

BACKGROUND: Sorghum (Sorghum bicolor) is a promising opportunity crop for arid regions of Africa due to its high tolerance to drought and heat stresses. Screening for genetic variability in photosynthetic regulation under salt stress can help to identify target trait combinations essential for sorghum genetic improvement. The primary objective of this study was to identify reliable indicators of photosynthetic performance under salt stress for forage yield within a panel of 18 sorghum varieties from stage 1 (leaf 3) to stage 7 (late flowering to early silage maturity). We dissected the genetic diversity and variability in five stress-sensitive photosynthetic parameters: nonphotochemical chlorophyll fluorescence quenching (NPQ), the electron transport rate (ETR), the maximum potential quantum efficiency of photosystem II (FV/FM), the CO2 assimilation rate (A), and the photosynthetic performance based on absorption (PIABS). Further, we investigated potential genes for target phenotypes using a combined approach of bioinformatics, transcriptional analysis, and homologous overexpression. RESULTS: The panel revealed polymorphism, two admixed subpopulations, and significant molecular variability between and within population. During the investigated development stages, the PIABS varied dramatically and consistently amongst varieties. Under higher saline conditions, PIABS also showed a significant positive connection with A and dry matter gain. Because PIABS is a measure of plants' overall photosynthetic performance, it was applied to predict the salinity performance index (SPI). The SPI correlated positively with dry matter gain, demonstrating that PIABS could be used as a reliable salt stress performance marker for forage sorghum. Eight rubisco large subunit genes were identified in-silico and validated using qPCR with variable expression across the varieties under saline conditions. Overexpression of Rubisco Large Subunit 8 increased PIABS, altered the OJIP, and growth with an insignificant effect on A. CONCLUSIONS: These findings provide insights into strategies for enhancing the photosynthetic performance of sorghum under saline conditions for improved photosynthetic performance and potential dry matter yield. The integration of molecular approaches, guided by the identified genetic variability, holds promise for genetically breeding sorghum tailored to thrive in arid and saline environments, contributing to sustainable agricultural practices.

Detection of closely linked QTLs and candidate genes controlling germination indices in response to drought and salinity stresses in barley.

The aim of current study was to identify closely linked QTLs and candidate genes related to germination indices under control, salinity and drought conditions in barley. A total of nine (a major), 28 (eight major) and 34 (five major) closely linked QTLs were mapped on the seven chromosomes in response to control, drought and salinity conditions using genome-wide composite interval mapping, respectively. The major QTLs can be used in marker-assisted selection (MAS) projects to increase tolerance to drought and salinity stresses during the germination. Overall, 422 unique candidate genes were associated with most major QTLs. Moreover, gene ontology analysis showed that candidate genes mostly involved in biological process related to signal transduction and response to stimulus in the pathway of resistance to drought and salinity stresses. Also, the protein-protein interaction network was identified 10 genes. Furthermore, 10 genes were associated with receptor-like kinase family. In addition, 16 transcription factors were detected. Three transcription factors including B3, bHLH, and FAR1 had the most encoding genes. Totally, 60 microRNAs were traced to regulate the target genes. Finally, the key genes are a suitable and reliable source for future studies to improve resistance to abiotic stress during the germination of barley.

Humic acid and grafting as sustainable agronomic practices for increased growth and secondary metabolism in cucumber subjected to salt stress.

Salinity stress poses a significant treat to crop yields and product quality worldwide. Application of a humic acid bio stimulant and grafting onto tolerant rootstocks can both be considered sustainable agronomic practices that can effectively ameliorate the negative effects of salinity stress. This study aimed to assess the above mentioned ameliorative effects of both practices on cucumber plants subjected to saline environments. To attain this goal a factorial experiment was carried out in the form of a completely randomized design with three replications. The three factors considered were (a) three different salinity levels (0, 5, and 10 dS m-1 of NaCl), (b) foliar application of humic acid at three levels (0, 100, and 200 mg L-1), and (c) both grafted and ungrafted plants. Vegetative traits including plant height, fresh and dry weight and number of leaf exhibited a significant decrease under increasing salinity stress. However, the application of humic acid at both levels mitigated these effects compared to control plants. The reduction in relative water content (RWC) of the leaf caused by salinity, was compensated by the application of humic acid and grafting. Thus, the highest RWC (86.65%) was observed in grafting plants with 0 dS m-1 of NaCl and 20 mg L-1 of humic acid. Electrolyte leakage (EL) increased under salinity stress, but the application of humic acid and grafting improved this trait and the lowest amount of EL (26.95%) was in grafting plants with 0 dS m-1 of NaCl and 20 mg L-1 of humic acid. The highest amount of catalase (0.53 mmol H2O2 g-1 fw min-1) and peroxidase (12.290 mmol H2O2 g-1 fw min-1) enzymes were observed in the treatment of 10 dS m-1 of NaCl and 200 mg L-1 humic acid. The highest amount of total phenol (1.99 mg g-1 FW), total flavonoid (0.486 mg g-1 FW), total soluble carbohydrate (30.80 mg g-1 FW), soluble protein (34.56 mg g-1 FW), proline (3.86 µg g-1 FW) was in grafting plants with 0 dS m-1 of NaCl and 200 mg L-1 of humic acid. Phenolic acids and phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO) enzymes increased with increasing salinity and humic acid levels. Contrary to humic acid, salt stress increased the sodium (Na+) and chlorine (Cl-) and decreased the amount of potassium (K+) and calcium (Ca2+) in the root and leaf of ungrafted cucumber. However, the application 200 mg L-1 humic acid appeared to mitigate these effects, thereby suggesting a potential role in moderating physiological processes and improving growth of cucumber plants subjected to salinity stress. According to the obtained results, spraying of humic acid (200 mg L-1) and the use of salt resistant rootstocks are recommended to increase tolerance to salt stress in cucumber. These results, for the first time, clearly demonstrated that fig leaf gourd a new highly salt-tolerant rootstock, enhances salt tolerance and improves yield and quality of grafted cucumber plants by reducing sodium transport to the shoot and increasing the amount of compatible osmolytes.

Genome-wide analysis of the SWEET gene family in Hemerocallis citrina and functional characterization of HcSWEET4a in response to salt stress.

Sugars will be eventually effluxed transporters (SWEETs) have been confirmed to play diverse physiological roles in plant growth, development and stress response. However, the characteristics and functions of the SWEET genes in Hemerocallis citrina remain unclear and poorly elucidated. In this study, the whole genome of Hemerocallis citrina was utilized to conduct bioinformatics analysis and a total of 19 HcSWEET genes were successfully identified. Analysis of the physicochemical properties indicated dominant differences among these HcSWEETs. A phylogenetic analysis revealed that HcSWEET proteins can be divided into 4 clades ranging from Clade I to IV, where proteins within the same clade exhibited shared conserved motifs and gene structures. Five to six exons were contained in the majority of HcSWEET genes, which were unevenly distributed across 11 chromosomes. The gene duplication analysis showed the presence of 4 gene pairs. Comparative syntenic maps revealed that the HcSWEET gene family might present more closed homology in monocotyledons than dicotyledons. Cis-acting element analysis of HcSWEET genes indicated key responsiveness to various hormones, light, and stresses. Additionally, transcriptome sequencing analysis suggested that most HcSWEET genes had a relatively higher expression in roots, and HcSWEET4a was significantly up-regulated under salt stress. Overexpression further verified the possibility that HcSWEET4a was involved in response to salt stress, which provides novel insights and facilitates in-depth studies of the functional analysis of HcSWEETs in resistance to abiotic stress.

The ameliorating effects of cinnamic acid-based nanocomposite against salt stress in peppermint.

Nanoparticles (NPs) are important in regulating plant tolerance to salt stress. Peppermint is one of the most widely used aromatic plants, with a high sensitivity to salt stress. The present study investigated physiological and biochemical factors to understand better the behavior of cinnamic acid (CA) and cinnamic acid nanocomposite in salinity control in peppermint plants. The first factor was salt stress with different salt concentrations, including 0, 50, 100, and 150 mg/L, the second factor was 50 µM CA, and the third factor was 50 µM CA nanocomposite based on carboxymethyl cellulose (CMC-CA NC). Results showed that stress markers increased with increasing salinity levels. On the contrary, plants treated with salinity showed a decrease in physiological and photosynthetic parameters, while the application of CA and CMC CA NC increased these critical parameters. Under salinity, compared to the control, malondialdehyde and hydrogen peroxide contents decreased by 11.3% and 70.4%, respectively. Furthermore, CA and CMC-CA NC enhanced peppermint tolerance to salinity by increasing compatible solute content such as proline, free amino acids, protein content, and soluble carbohydrates, increasing antioxidant enzymes, and decreasing stress markers in plant tissues. Compared to the control, chlorophyll fluorescence and proline content increased by 1.1% and 172.1%, respectively. Salinity stress negatively affected all physiological and biochemical parameters, but CA and CMC-CA NC treatments improved them. We concluded that the nanocomposite, a biostimulant, significantly enhances mint tolerance under salinity conditions.

Aerial signaling by plant-associated Streptomyces setonii WY228 regulates plant growth and enhances salt stress tolerance.

Plant-associated streptomycetes play important roles in plant growth and development. However, knowledge of volatile-mediated crosstalk between Streptomyces spp. and plants remains limited. In this study, we investigated the impact of volatiles from nine endophytic Streptomyces strains on the growth and development of plants. One versatile strain, Streptomyces setonii WY228, was found to significantly promote the growth of Arabidopsis thaliana and tomato seedlings, confer salt tolerance, and induce early flowering and increased fruit yield following volatile treatment. Analysis of plant growth-promoting traits revealed that S. setonii WY228 could produce indole-3-acetic acid, siderophores, ACC deaminase, fix nitrogen, and solubilize inorganic phosphate. These capabilities were further confirmed through genome sequencing and analysis. Volatilome analysis indicated that the volatile organic compounds emitted from ISP-2 medium predominantly comprised sesquiterpenes and 2-ethyl-5-methylpyrazine. Further investigations showed that 2-ethyl-5-methylpyrazine and sesquiterpenoid volatiles were the primary regulators promoting growth, as confirmed by experiments using the terpene synthesis inhibitor phosphomycin, pure compounds, and comparisons of volatile components. Transcriptome analysis, combined with mutant and inhibitor studies, demonstrated that WY228 volatiles promoted root growth by activating Arabidopsis auxin signaling and polar transport, and enhanced root hair development through ethylene signaling activation. Additionally, it was confirmed that volatiles can stimulate plant abscisic acid signaling and activate the MYB75 transcription factor, thereby promoting anthocyanin synthesis and enhancing plant salt stress tolerance. Our findings suggest that aerial signaling-mediated plant growth promotion and abiotic stress tolerance represent potentially overlooked mechanisms of Streptomyces-plant interactions. This study also provides an exciting strategy for the regulation of plant growth and the improvement of horticultural crop yields within sustainable agricultural practices.

Surviving the stress: Understanding the molecular basis of plant adaptations and uncovering the role of mycorrhizal association in plant abiotic stresses.

Environmental stresses severely impair plant growth, resulting in significant crop yield and quality loss. Among various abiotic factors, salt and drought stresses are one of the major factors that affect the nutrients and water uptake by the plants, hence ultimately various physiological aspects of the plants that compromises crop yield. Continuous efforts have been made to investigate, dissect and improve plant adaptations at the molecular level in response to drought and salinity stresses. In this context, the plant beneficial microbiome presents in the rhizosphere, endosphere, and phyllosphere, also referred as second genomes of the plant is well known for its roles in plant adaptations. Exploration of beneficial interaction of fungi with host plants known as mycorrhizal association is one such special interaction that can facilitates the host plants adaptations. Mycorrhiza assist in alleviating the salinity and drought stresses of plants via redistributing the ion imbalance through translocation to different parts of the plants, as well as triggering oxidative machinery. Mycorrhiza association also regulates the level of various plant growth regulators, osmolytes and assists in acquiring minerals that are helpful in plant's adaptation against extreme environmental stresses. The current review examines the role of various plant growth regulators and plants' antioxidative systems, followed by mycorrhizal association during drought and salt stresses.

Genome-wide identification and expression analysis of TPP gene family under salt stress in peanut (Arachis hypogaea L.).

Trehalose-6-phosphate phosphatase (TPP), a key enzyme for trehalose biosynthesis in plants, plays a pivotal role in the growth and development of higher plants, as well as their adaptations to various abiotic stresses. Employing bioinformatics techniques, 45 TPP genes distributed across 17 chromosomes were identified with conserved Trehalose-PPase domains in the peanut genome, aiming to screen those involved in salt tolerance. Collinearity analysis showed that 22 TPP genes from peanut formed homologous gene pairs with 9 TPP genes from Arabidopsis and 31 TPP genes from soybean, respectively. Analysis of cis-acting elements in the promoters revealed the presence of multiple hormone- and abiotic stress-responsive elements in the promoter regions of AhTPPs. Expression pattern analysis showed that members of the TPP gene family in peanut responded significantly to various abiotic stresses, including low temperature, drought, and nitrogen deficiency, and exhibited certain tissue specificity. Salt stress significantly upregulated AhTPPs, with a higher number of responsive genes observed at the seedling stage compared to the podding stage. The intuitive physiological effect was reflected in the significantly higher accumulation of trehalose content in the leaves of plants under salt stress compared to the control. These findings indicate that the TPP gene family plays a crucial role in peanut's response to abiotic stresses, laying the foundation for further functional studies and utilization of these genes.

Eco-evolutionary strategies for relieving carbon limitation under salt stress differ across microbial clades.

With the continuous expansion of saline soils under climate change, understanding the eco-evolutionary tradeoff between the microbial mitigation of carbon limitation and the maintenance of functional traits in saline soils represents a significant knowledge gap in predicting future soil health and ecological function. Through shotgun metagenomic sequencing of coastal soils along a salinity gradient, we show contrasting eco-evolutionary directions of soil bacteria and archaea that manifest in changes to genome size and the functional potential of the soil microbiome. In salt environments with high carbon requirements, bacteria exhibit reduced genome sizes associated with a depletion of metabolic genes, while archaea display larger genomes and enrichment of salt-resistance, metabolic, and carbon-acquisition genes. This suggests that bacteria conserve energy through genome streamlining when facing salt stress, while archaea invest in carbon-acquisition pathways to broaden their resource usage. These findings suggest divergent directions in eco-evolutionary adaptations to soil saline stress amongst microbial clades and serve as a foundation for understanding the response of soil microbiomes to escalating climate change.

Comprehensive analysis of Alfin-like transcription factors associated with drought and salt stresses in wheat (Triticum aestivum L.).

BACKGROUND: Alfin-like proteins are a kind of plant-specific transcription factors, and play vital roles in plant growth, development and stress responses. RESULTS: In this study, a total of 27 Alfin-like transcription factors were identified in wheat. TaAL genes were unevenly distributed on chromosome. Phylogenetic analysis showed TaAL genes were divided into AL-B and AL-C subfamilies, and TaALs with closer evolutionary relationships generally shared more similar exon-intron structures and conserved motifs. The cis-acting element analysis showed MBS, ABRE and CGTCA-motif were the most common in TaAL promoters. The interacting proteins and downstream target genes of TaAL genes were also investigated in wheat. The transcriptome data and real-time PCR results indicated TaAL genes were differentially expressed under drought and salt stresses, and TaAL1-B was significantly up-regulated in response to drought stress. In addition, association analysis revealed that TaAL1-B-Hap-I allelic variation had significantly higher survival rate compared to TaAL1-B-Hap-II under drought stress. CONCLUSIONS: These results will provide vital information to increase our understanding of the Alfin-like gene family in wheat, and help us in breeding better wheat varieties in the future.

Comprehensive genome-wide identification of Snf2 gene family and their expression profile under salt stress in six Brassica species of U's triangle model.

MAIN CONCLUSION: We comprehensively identified and analyzed the Snf2 gene family. Some Snf2 genes were involved in responding to salt stress based on the RNA-seq and qRT-PCR analysis. Sucrose nonfermenting 2 (Snf2) proteins are core components of chromatin remodeling complexes that not only alter DNA accessibility using the energy of ATP hydrolysis, but also play a critical regulatory role in growth, development, and stress response in eukaryotes. However, the comparative study of Snf2 gene family in the six Brassica species in U's triangle model remains unclear. Here, a total of 405 Snf2 genes were identified, comprising 53, 50, and 46 in the diploid progenitors: Brassica rapa (AA, 2n = 20), Brassica nigra (BB, 2n = 16), and Brassica oleracea (CC, 2n = 18), and 93, 91, and 72 in the allotetraploid: Brassica juncea (AABB, 2n = 36), Brassica napus (AACC, 2n = 38), and Brassica carinata (BBCC, 2n = 34), respectively. These genes were classified into six clades and further divided into 18 subfamilies based on their conserved motifs and domains. Intriguingly, these genes showed highly conserved chromosomal distributions and gene structures, indicating that few dynamic changes occurred during the polyploidization. The duplication modes of the six Brassica species were diverse, and the expansion of most Snf2 in Brassica occurred primarily through dispersed duplication (DSD) events. Additionally, the majority of Snf2 genes were under purifying selection during polyploidization, and some Snf2 genes were associated with various abiotic stresses. Both RNA-seq and qRT-PCR analysis showed that the expression of BnaSnf2 genes was significantly induced under salt stress, implying their involvement in salt tolerance response in Brassica species. The results provide a comprehensive understanding of the Snf2 genes in U's triangle model species, which will facilitate further functional analysis of the Snf2 genes in Brassica plants.

Structural and molecular dynamics simulation studies of CBL-interacting protein kinase CIPK and its complexes related to plant salinity stress.

CONTEXT: Calcium-dependent signaling in plants is responsible for several major cellular events, including the activation of the salinity-responsive pathways. Calcium binds to calcineurin B-like protein (CBL), and the resulting CBL-Ca2+ complex binds to CBL-interacting protein kinase (CIPK). The CBL-CIPK complex enhances the CIPK interaction with an upstream kinase. The upstream kinase phosphorylates CIPK that, in turn, phosphorylates membrane transporters. Phosphorylation influences transporter activity to kick-start many downstream functions, such as balancing the cytosolic Na+-to-K+ ratio. The CBL-CIPK interaction is pivotal for Ca2+-dependent salinity stress signaling. METHODS: Computational methods are used to model the entire Arabidopsis thaliana CIPK24 protein structure in its autoinhibited and open-activated states. Arabidopsis thaliana CIPK24-CBL4 complex is predicted based on the protein-protein docking methods. The available structural and functional data support the CIPK24 and the CIPK24-CBL4 complex models. Models are energy-minimized and subjected to molecular dynamics (MD) simulations. MD simulations for 500 ns and 300 ns enabled us to predict the importance of conserved residues of the proteins. Finally, the work is extended to predict the CIPK24-CBL4 complex with the upstream kinase GRIK2. MD simulation for 300 ns on the ternary complex structure enabled us to identify the critical CIPK24-GRIK2 interactions. Together, these data could be used to engineer the CBL-CIPK interaction network for developing salt tolerance in crops.

Genome-Wide Identification of GRAS Transcription Factors and Their Functional Analysis in Salt Stress Response in Sugar Beet.

GAI-RGA-and-SCR (GRAS) transcription factors can regulate many biological processes such as plant growth and development and stress defense, but there are few related studies in sugar beet. Salt stress can seriously affect the yield and quality of sugar beet (Beta vulgaris). Therefore, this study used bioinformatics methods to identify GRAS transcription factors in sugar beet and analyzed their structural characteristics, evolutionary relationships, regulatory networks and salt stress response patterns. A total of 28 BvGRAS genes were identified in the whole genome of sugar beet, and the sequence composition was relatively conservative. According to the topology of the phylogenetic tree, BvGRAS can be divided into nine subfamilies: LISCL, SHR, PAT1, SCR, SCL3, LAS, SCL4/7, HAM and DELLA. Synteny analysis showed that there were two pairs of fragment replication genes in the BvGRAS gene, indicating that gene replication was not the main source of BvGRAS family members. Regulatory network analysis showed that BvGRAS could participate in the regulation of protein interaction, material transport, redox balance, ion homeostasis, osmotic substance accumulation and plant morphological structure to affect the tolerance of sugar beet to salt stress. Under salt stress, BvGRAS and its target genes showed an up-regulated expression trend. Among them, BvGRAS-15, BvGRAS-19, BvGRAS-20, BvGRAS-21, LOC104892636 and LOC104893770 may be the key genes for sugar beet's salt stress response. In this study, the structural characteristics and biological functions of BvGRAS transcription factors were analyzed, which provided data for the further study of the molecular mechanisms of salt stress and molecular breeding of sugar beet.

The Role of PGPB-Microalgae interaction in Alleviating Salt Stress in Plants.

Plant development and yield are severely hampered by climate change. Plants are very prone to a variety of abiotic stressors during growth, making them susceptible to destruction which can reduce the productivity by 20-60%. These stresses generate reactive oxygen species (ROS), which damage lipids, proteins, and nucleic acids. Microalgae and plant growth-promoting bacteria (PGPB) are remarkably effective at reducing the effects of salt stress and promoting plant growth, thereby increasing agricultural yield, and helping ensure global food security. Through a variety of mechanisms, including the production of phytohormones, 1-aminocyclopropane-1-carboxylic acid deaminase, exopolysaccharide, siderophores, hydrogen cyanide, extracellular polymeric substances, volatile organic compounds, and modulation of antioxidants defense machinery under abiotic stresses promote plant growth after inoculation of PGPB and microalgae. These microorganisms also maintain ion homeostasis, offer osmotic balance, stimulate genes that respond to salt and drought, rewire the metabolism, modify the transcription of ion transporter genes, and more. To counteract the negative consequences of salinity stress, this study summarizes the effects of PGPB- microalgae along with a tentative protective mechanism during salinity stress for sustainable agriculture.