Salt Stress Research Articles

The Maize Gene ZmGLYI-8 Confers Salt and Drought Tolerance in Transgenic Arabidopsis Plants.

Methylglyoxal (MG), a highly reactive and cytotoxic α-oxoaldehyde compound, can over-accumulate under abiotic stress, consequently injuring plants or even causing death. Glyoxalase I (GLYI), the first enzyme of the glyoxalase pathway, plays multiple roles in the detoxification of MG and in abiotic stress responses. However, the GLY1 gene in maize has been little studied in response to abiotic stress. In this study, we screened a glyoxalase I gene (ZmGLYI-8) and overexpressed in Arabidopsis. This gene was localized in the cytoplasm and can be induced in maize seedlings under multiple stress treatments, including salt, drought, MG, ABA, H2O2 and high temperature stress. Phenotypic analysis revealed that after MG, salt and drought stress treatments, overexpression of ZmGLYI-8 increased the tolerance of transgenic Arabidopsis to MG, salt and drought stress. Furthermore, we demonstrated that the overexpression of ZmGLYI-8 scavenges accumulated reactive oxygen species, detoxifies MG and enhances the activity of antioxidant enzymes to improve the resistance of transgenic Arabidopsis plants to salt and drought stress. In summary, this study preliminarily elucidates the molecular mechanism of the maize ZmGLYI-8 gene in transgenic Arabidopsis and provides new insight into the breeding of salt- and drought-tolerant maize varieties.

Exogenous Melatonin Reinforces Photosynthesis, Antioxidant Defense and Gene Expression to Ameliorate Na2CO3 Stress in Maize.

Salt stress can seriously affect the growth and development of maize (Zea mays L.), resulting in a great yield loss. Melatonin (MT), an indole hormone, is a potential enhancer of plant tolerance against salt stress. However, the complex mechanisms of MT application in enhancing maize salt tolerance are still unclear. Herein, three-leaf seedlings of salt-susceptible P138 and its salt-resistant ethyl methane sulfonate (EMS)-104 mutant were cultured with or without 150 μM MT application under 0 and 100 mM Na2CO3 treatments for seven days, to systematically explore the response mechanisms of exogenous MT in improving the salt tolerance of maize. The results showed that salt stress triggered an escalation in reactive oxygen species production, enhanced multiple antioxidant enzymes' activities, impaired cellular membrane permeability, inhibited photosynthetic pigment accumulation, and ultimately undermined the vigor and photosynthetic prowess of the seedlings. While suitable MT application counteracted the detrimental impacts of Na2CO3 on seedlings' growth and photosynthetic capacity, the seedling length and net photosynthetic rate of P138 and EMS-104 were increased by 5.5% and 18.7%, and 12.7% and 54.5%, respectively. Quantitative real-time PCR (qRT-PCR) analysis further showed that MT application activated the expression levels of antioxidant enzyme-related genes (Zm00001d025106, Zm00001d031908, Zm00001d027511, and Zm00001d040364) and pigment biosynthesis-related genes (Zm00001d011819 and Zm00001d017766) in both maize seedlings under Na2CO3 stress; they then formed a complex interaction network of gene expression, multiple physiological metabolisms, and phenotype changes to influence the salt tolerance of maize seedlings under MT or Na2CO3 stress. To sum up, these observations underscore that 150 μM MT can alleviate salt injury of maize seedlings, which may provide new insights for further investigating MT regulation mechanisms to enhance maize seedlings' salt resistance.

AtC3H3, an Arabidopsis Non-TZF Gene, Enhances Salt Tolerance by Increasing the Expression of Both ABA-Dependent and -Independent Stress-Responsive Genes

Salinity causes widespread crop loss and prompts plants to adapt through changes in gene expression. In this study, we aimed to investigate the function of the non-tandem CCCH zinc-finger (non-TZF) protein gene AtC3H3 in response to salt stress in Arabidopsis. AtC3H3, a gene from the non-TZF gene family known for its RNA-binding and RNase activities, was up-regulated under osmotic stress, such as high salt and drought. When overexpressed in Arabidopsis, AtC3H3 improved tolerance to salt stress, but not drought stress. The expression of well-known abscisic acid (ABA)-dependent salt stress-responsive genes, namely Responsive to Desiccation 29B (RD29B), RD22, and Responsive to ABA 18 (RAB18), and representative ABA-independent salt stress-responsive genes, namely Dehydration-Responsive Element Binding protein 2A (DREB2A) and DREB2B, was significantly higher in AtC3H3-overexpressing transgenic plants (AtC3H3 OXs) than in wild-type plants (WT) under NaCl treatment, indicating its significance in both ABA-dependent and -independent signal transduction pathways. mRNA-sequencing (mRNA-Seq) analysis using NaCl-treated WT and AtC3H3 OXs revealed no potential target mRNAs for the RNase function of AtC3H3, suggesting that the potential targets of AtC3H3 might be noncoding RNAs and not mRNAs. Through this study, we conclusively demonstrated that AtC3H3 plays a crucial role in salt stress tolerance by influencing the expression of salt stress-responsive genes. These findings offer new insights into plant stress response mechanisms and suggest potential strategies for improving crop resilience to salinity stress.

Exogenous Calcium can Promote Nutrient Uptake and Stoichiometric Balance of Mulberry Seedlings Under Salt Stress

Exogenous Calcium can Promote Nutrient Uptake and Stoichiometric Balance of Mulberry Seedlings Under Salt Stress

Understanding of Plant Salt Tolerance Mechanisms and Application to Molecular Breeding.

Soil salinization is a widespread hindrance that endangers agricultural production and ecological security. High salt concentrations in saline soils are primarily caused by osmotic stress, ionic toxicity and oxidative stress, which have a negative impact on plant growth and development. In order to withstand salt stress, plants have developed a series of complicated physiological and molecular mechanisms, encompassing adaptive changes in the structure and function of various plant organs, as well as the intricate signal transduction networks enabling plants to survive in high-salinity environments. This review summarizes the recent advances in salt perception under different tissues, physiological responses and signaling regulations of plant tolerance to salt stress. We also examine the current knowledge of strategies for breeding salt-tolerant plants, including the applications of omics technologies and transgenic approaches, aiming to provide the basis for the cultivation of salt-tolerant crops through molecular breeding. Finally, future research on the application of wild germplasm resources and muti-omics technologies to discover new tolerant genes as well as investigation of crosstalk among plant hormone signaling pathways to uncover plant salt tolerance mechanisms are also discussed in this review.

Genome-Wide Identification and Functional Validation of Actin Depolymerizing Factor (ADF) Gene Family in Gossypium hirsutum L.

The Actin Depolymerizing Factor (ADF) protein, highly conserved among eukaryotes, is essential for plant growth, development, and stress responses. Cotton, a vital economic crop with applications spanning oilseed, textiles, and military sectors, has seen a limited exploration of its ADF gene family. This research has identified 118 unique ADF sequences across four principal cotton species: Gossypium hirsutum L., Gossypium barbadense Linn, Gossypium raimondii, and Asiatic cotton. The study found that the structural domains and physicochemical properties of these proteins are largely uniform across species. The ADF genes were classified into four subfamilies with a notable expansion in groups III and IV due to tandem and chromosomal duplication events. A thorough analysis revealed a high degree of conservation in gene structure, including exon counts and the lengths of introns and exons, with the majority of genes containing three exons, aligning with the characteristics of the ADF family. RNA-seq analysis uncovered a spectrum of responses by GhADFs to various abiotic stresses with GhADF19 showing the most significant reaction. Virus-induced gene silencing (VIGS) experiments were conducted to assess the role of GhADF19 in plant growth under abiotic stress. The results demonstrated that plants with silenced GhADF19 exhibited significantly slower growth rates and lower dry weights when subjected to cold, salt, and drought stress compared to the control group. This marked reduction in growth and dry weight under stress conditions highlights the potential importance of GhADF19 in stress tolerance mechanisms.

Marker-Assisted Selection of Jacalin-Related Lectin Genes OsJRL45 and OsJRL40 Derived from Sea Rice 86 Enhances Salt Tolerance in Rice.

Soil salinization limits rice growth and is an important restriction on grain yield. Jacalin-related lectins are involved in multiple stress responses, but their role in salt stress responses and use as molecular markers for salt tolerance remain poorly understood. Salt stress treatments and RT-qPCR analyses of Sea Rice 86 (SR86), 9311, and Nipponbare (Nip) showed that OsJRL45 and OsJRL40 enhanced tolerance of salt stress in SR86. Molecular markers based on sequence differences in SR86 and the salt-sensitive variety, 9311, in the intergenic region between OsJRL45 and OsJRL40 were validated in recombinant inbred lines derived from SR86 and 9311, hybrid populations, and common rice varieties. Yeast two-hybrid and bimolecular fluorescence complementation demonstrated that OsJRL45 and OsJRL40 interacted. Co-transformation of Nip with OsJRL45 and OsJRL40 derived from SR86 had no effect on the mature phenotype in T2 plants; however, salt stress at the three-leaf stage led to significant increases in CAT, POD, SOD, and Pro contents, but reduced MDA content in transgenic plants. Transcriptomic analysis identified 834 differentially expressed genes in transgenic plants under salt stress. GO and KEGG enrichment analyses indicated that metabolic pathways related to antioxidant responses and osmotic balance were crucial for salt-stress tolerance. Thus, molecular markers based on nucleotide differences in OsJRL45 and OsJRL40 provide a novel method for identifying salt-tolerant rice varieties.

GhMAC3e is involved in plant growth and defense response to Verticillium dahliae.

GhMAC3e expression was induced by various stresses and hormones. GhMAC3e may regulate plant growth by influencing auxin distribution, and play important roles in Verticillium wilt resistance via mediating SA signaling. The MOS4-Associated Complex (MAC) is a highly conserved protein complex involved in pre-mRNA splicing and spliceosome assembly, which plays a vital role in plant immunity. It comprises key components such as MOS4, CDC5, and PRL1. MAC3A/B, as U-box E3 ubiquitin ligases, are crucial for various plant processes including development, stress responses, and disease resistance. However, their roles in cotton remain largely unknown. In this study, we first cloned the GhMAC3e gene from cotton and explored its biological functions by using virus-induced gene silencing (VIGS) in cotton and transgenic overexpression in Arabidopsis. The results showed that GhMAC3e is ubiquitously expressed in cotton tissues and could be induced by salt stress, Verticillium dahliae (VD) infection, PEG, ABA, ETH, GA3, MeJA, and SA. Silencing GhMAC3e retarded primary stem growth and reduced biomass of cotton coupled with the reduced auxin content in the petioles and veins. Silencing GhMAC3e up-regulated expression of cell growth-related genes GhXTH16 and Gh3.6, while down-regulated GhSAUR12 expression. Ectopic expression of GhMAC3e in Arabidopsis significantly enhanced its resistance to Verticillium wilt (VW) in terms of decreased pathogen biomass and lowered plant mortality. Overexpression of GhMAC3e dramatically upregulated AtPR1 by around 15 fold and more than 262 fold under basal and VD inoculation condition, respectively. This change was not associated with the expression of GhNPR1. In conclusion, GhMAC3e may not only regulate plant growth by influencing auxin distribution and growth-related gene expression, but also play important roles in VW resistance via mediating SA signaling independent of NPR1 transcription level.

MpPUB9, a U-box E3 ubiquitin ligase, acts as a positive regulator by promoting the turnover of MpEXO70.1 under high salinity in Marchantia polymorpha.

Marchantia polymorpha, occupying a basal position in the monophyletic assemblage of land plants, displays a notable expansion of plant U-box (PUB) proteins compared with those in animals. We elucidated the roles of MpPUB9 in regulating salt stress tolerance in M. polymorpha. MpPUB9 expression was rapidly induced by high salinity and dehydration. MpPUB9 possessed an intact U-box domain in the N-terminus. MpPUB9-Citrine localized to punctate structures and was peripherally associated with microsomal membranes. Phenotypic analyses demonstrate that the hyponastic and epinastic thallus growth phenotypes, which were induced by the overexpression and suppression of MpPUB9, may provoke salt stress-resistant and -susceptible phenotypes, respectively. MpPUB9 was also found to directly interact with the exocyst protein MpEXO70.1, leading to its ubiquitination. Under high-salinity conditions, though the stability of MpPUB9 was dramatically increased, MpEXO70.1 showed slightly faster turnover rates. Transcriptome analyses showed that salt treatment and the overexpression of MpPUB9 co-upregulated the genes related to the modulation of H2O2 and cell wall organization. Overall, our results suggest that MpPUB9 plays a crucial role in the positive regulation of salt stress tolerance, resulting from its interaction with MpEXO70.1 and modulating turnover of the protein under high-salt conditions via the coordination of UPS with autophagy.

Root System Architecture and Salt Stress Responses in Cereal Crops

Root System Architecture and Salt Stress Responses in Cereal Crops

Influence of drought and salt stress on almond nutrition

Increased drought and salinity is a threat to agriculture in arid and semiarid zone worldwide. Almond is nutritious, rich in minerals protein and fiber with increasing world demand and production. The objective was to determine the effect of drought and salinity stress on nutrient concentrations in almond trees. Almond is known as sensitive to salt stress compared to other trees. There are limited studies on almond nutrition uptake under salt and drought stress conditions. This study had three drought and four salinity levels, and combined applications for a total of 12 treatments each with three replications. Drought increased K, Mg, Ca, Na and Cl concentrations in leaves, yet, decreased B concentrations. Similarly under salinity, almond leaves increased in K, Mg and Ca concentrations (as well as in Na and Cl). This study showed that the nutrient uptake varies under drought and salt stress conditions. Mineral nutrition should be taken into consideration, fertilization needs to account for stress factors.

Integrated Metabolome and Transcriptome Analyses Reveal the Mechanisms Regulating Flavonoid Biosynthesis in Blueberry Leaves under Salt Stress

The flavonoids play important roles in plant salt tolerance. Blueberries (Vaccinium spp.) are extremely sensitive to soil salt increases. Therefore, improving the salt resistance of blueberries by increasing the flavonoid content is crucial for the development of the blueberry industry. To explore the underlying molecular mechanism, we performed an integrated analysis of the metabolome and transcriptome of blueberry leaves under salt stress. We identified 525 differentially accumulated metabolites (DAMs) under salt stress vs. control treatment, primarily including members of the flavonoid class. We also identified 20,920 differentially expressed genes (DEGs) based on transcriptome data; of these, 568 differentially expressed transcription factors (TFs) were annotated, and bHLH123, OsHSP20, and HSP20 TFs might be responsible for blueberry leaf salt tolerance. DEGs involved in the flavonoid biosynthesis pathway were significantly enriched at almost all stages of salt stress. Salt treatment upregulated the expression of most flavonoid biosynthetic pathway genes and promoted the accumulation of flavonols, flavonol glycosides, flavans, proanthocyanidins, and anthocyanins. Correlation analysis suggested that 4-coumarate CoA ligases (4CL5 and 4CL1) play important roles in the accumulation of flavonols (quercetin and pinoquercetin) and flavan-3-ol (epicatechin and prodelphinidin C2) under salt stress, respectively. The flavonoid 3′5′-hydroxylases (F3′5′H) regulate anthocyanin (cyanidin 3-O-beta-D-sambubioside and delphinidin-3-O-glucoside chloride) biosynthesis, and leucoanthocyanidin reductases (LAR) are crucial for the biosynthesis of epicatechin and prodelphinidin C2 during salt stress. Taken together, it is one of the future breeding goals to cultivate salt-resistant blueberry varieties by increasing the expression of flavonoid biosynthetic genes, especially 4CL, F3′5′H, and LAR genes, to promote flavonoid content in blueberry leaves.

Overexpression of CrSMT gene enhances salt stress tolerance by improving cotton peroxidation resistance

Salt stress is an important abiotic stress factor affecting crop production and plant geographical distribution. Salt stress negatively impacts molecular, biochemical, and physiological processes in cotton, resulting in inhibition of plant growth and development and, in severe cases, plant death. In this experiment, the CrSMT gene isolated from the unicellular eukaryote Chlamydomonas reinhardtii was overexpressed in cotton R15. Two transgenic lines, L17 and L25, were obtained. Treated with 200 mM NaCl experiments showed that the CrSMT-transgenic cotton had enhanced tolerance to salt stress. RNA-seq analysis revealed that CrSMT overexpression in cotton resulted in the synthesis of a large number of secondary metabolites responsive to salt stress. Correlation analysis between the wild type and the transgenic lines revealed that CrSMT overexpression did not affect the growth, agronomic traits, and fiber quality of cotton. The function of CrSMT holds potential to improve plant tolerance of abiotic stress factors.

YOLOv8-licorice: a lightweight salt-resistance detection method for licorice based on seed germination state.

Seeds will display different germination states during the germination process, and their good or bad state directly influences the subsequent growth and yield of the crop. This study aimed to address the difficulties of obtaining the images of seed germination process in all time series and studying the dynamic evolution law of seed germination state under stress conditions. A licorice sprouting experiment was performed using a seed sprouting phenotype acquisition system to obtain images of the sprouting process of licorice in full-time sequence. A labeled dataset of licorice full-time sequence sprouting process images was constructed based on the four states of unsprouted, sprouted, cracked, and shelled in the sprouting process. An optimized model, YOLOv8-Licorice, was developed based on the YOLOv8-n model and its effectiveness was demonstrated by comparative and ablation tests. Different salt stress environments were simulated via NaCl aqueous solution concentration, and germination experiments of licorice seeds were performed under different salt stresses. The germination state of licorice under different salt stress environments was detected using the YOLOv8-Licorice detection model. Percentage curve of licorice seeds in an unsprouted state displayed a continuous decreasing trend. For the percentage curve of licorice seeds in the sprouted state, an increasing and then decreasing trend was observed under the condition of 0-200 mmol/L NaCl solution, and a continuous increasing trend was observed under the condition of 240-300 mmol/L NaCl solution. Licorice seeds in the cracked state demonstrated percentage curves with an increasing and then decreasing trend under the condition of 0-140 mmol/L NaCl solution and a continuous increasing trend under the condition of 160-300 mmol/L NaCl solution. The percentage curve of licorice seeds in shelled state displayed a continuous increasing trend in 0-200 mmol/L NaCl solution condition and remained horizontal in 220-300 mmol/L NaCl solution condition. Overall, this study provides a valuable method involving the seed sprouting phenotype acquisition system and the proposed method for detecting the germination state of licorice seeds. This method serves as a valuable reference to comprehensively understand the seed sprouting process under triggering treatment.

Opportunities and limits of image-based plant stress phenotyping: detecting plant salt stress status using machine learning techniques

Abstract Plant stress phenotyping is a useful tool to facilitate targeted interventions and optimize management practices of plants growing in stressful conditions. However, various technical challenges still need to be overcome, though, and there is a clear need for investigating functional traits that can be used as a proxy for stress prediction, especially for abiotic stresses. This experimental work leveraged machine learning classification models to detect salt stress in two populations of a non-model species, combining image-based approaches (i.e. both manual and automated) and minimal morpho-physiological/biochemical analyses. A small set of specific features, combining malondialdehyde content with other non-destructive image-derived traits, such as Chroma Difference and Chroma Ratio indices, was able to distinguish non-stressed from stressed plants (2-class model; precision: 0.91) as well as stress intensity (3-class model; precision: 0.84). This flexible approach can be adapted to different plant developmental stages and leaf shape/morphology. In the future, the robustness and reliability of the models should be tested in other species and other abiotic stresses, such as drought.

Phosphoproteome modulation by nucleoside diphosphate kinase affects photosynthesis & stress tolerance of Nostoc PCC 7120

Nucleoside diphosphate kinase (Ndk/NDK/NDPK) is known to possess pleiotropic functions, one of which is that as a protein kinase, and has been shown to be involved in stress tolerance in plants. To assess its role in the cyanobacterium Nostoc PCC 7120, which is hitherto unreported, recombinant strain overexpressing Ndk, Anndk+ was generated. Phosphoproteomic analysis of Anndk+ and its comparison with that of the vector control, AnpAM, revealed differential phosphorylation at S/T/Y sites of proteins belonging to varied functional groups, with over 17 % phosphoproteins involved in photosynthesis. A total of 177 phosphopeptides and 117 phosphoproteins were identified, including newly identified phosphopeptides in any cyanobacteria. Compared to AnpAM, the Anndk+ cells exhibited (i) lower photosynthetic efficiency and electron transport rate at low PAR (photosynthetically active radiation), (ii) no change in photochemical quenching across PAR, (iii) but distinct non-photochemical quenching [zero Y(NPQ) and high Y(NO) in Anndk+ and high Y(NPQ) and low (NO) in AnpAM], and (iv) increased tolerance to γ-radiation, oxidative, salt and DCMU stresses. The observed modulation of phosphoproteome linked to physiological changes upon overexpression of Ndk in Nostoc could be a combination of direct protein kinase activity of Ndk and/or indirectly through other protein kinases and phosphatases whose phosphorylation status is mediated by Ndk. This is the first report on a direct correlation between Ndk levels, phosphorylation status of proteins and stress tolerance in any cyanobacteria.

Genomic Analysis and Expression Dynamics of GH3 Genes Under Abiotic Stresses in Brassica rapa

ABSTRACTIn silico characterization of the Gretchen Hagen3 (GH3) gene family is required for understanding phytohormone regulation and stress responses in Brassica rapa to develop the improved stress‐tolerant cultivars. The main objective of this research was to identify the key BrGH3 genes under different abiotic stresses. Using bioinformatics tools, a total of 27 BrGH3 genes were identified in B. rapa for which phylogenetic relationship, syntenic pairing, conserved motifs, miRNA regulation, and cis‐regulatory elements of BrGH3s were also studied. BrGH3 gene expression has been examined in numerous tissues and under various abiotic and phytohormone stressors. Phylogenetic studies separated BrGH3 genes into three major classes and nine subclasses based on gene functional evolution. Collinearity analysis demonstrated that all BrGH3 genes had syntenic linkage with AtGH3, BnaGH3, and BolGH3, indicating that genome duplication mechanisms were crucial to BrGH3 gene evolution. The expression dynamics of BrGH3 under diverse phytohormonal stresses methyl jasmonate (MeJA), auxin (IAA), abscisic acid (ABA), gibberellic acid (GA), and salicylic acid (SA) at different time intervals suggest that BrGH3‐5.1 has a consistently greater expression than other BrGH3 genes. Under salt, drought, and low temperature stress, BrGH3‐1 and BrGH3‐4 genes expressed comparatively higher. The findings suggest that five genes (BrGH3‐5.1, BrGH3‐5.2, BrGH3‐15, BrGH3‐17.2, and BrGH3‐19) have a key role in inducing broad stress resilience. These results can be beneficial in developing stress‐tolerant varieties of Chinese cabbage.

HES1 potentiates high salt stress response as an enhancer of NFAT5-DNA binding

High salt conditions and subsequent hyperosmolarity are injurious cellular stresses that can activate immune signaling. Nuclear factor of activated T-cells 5 (NFAT5) is an essential transcription factor that induces osmoprotective genes such as aldose reductase (AR) and betaine-GABA transporter 1 (BGT1). High salt stress-mediated NFAT5 activation is also reported to accelerate the inflammatory response and autoimmune diseases. However, the systemic regulation of NFAT5 remains unclear. Here, we performed a genome-wide siRNA screen to comprehensively identify the regulators of NFAT5. We monitored NFAT5 nuclear translocation and identified one of the Notch signaling effectors, Hairy and enhancer of split-1 (HES1), as a positive regulator of NFAT5. HES1 was induced by high salinity via ERK signaling and facilitated NFAT5 recruitment to its target promoter region, resulting in the proper induction of osmoprotective genes and cytoprotection under high salt stress. These findings suggest that, though HES1 is well known as a transcriptional repressor, it positively regulates NFAT5-dependent transcription in the context of a high salinity/hyperosmotic response.

The Optimal Drought Hardening Intensity and Salinity Level Combination for Tomato (Solanum lycopersicum L.) Cultivation under High-Yield, High-Quality and Water-Saving Multi-Objective Demands.

The extreme weather and the deteriorating water environment have exacerbated the crisis of freshwater resource insufficiency. Many studies have shown that salty water could replace freshwater to partly meet the water demand of plants. To study the effects of early-stage drought hardening and late-stage salt stress on tomatoes (Solanum lycopersicum L.), we conducted a 2-year pot experiment. Based on the multi-objective demands of high yield, high quality, and water saving, yield indicators, quality indicators, and a water-saving indicator were selected as evaluation indicators. Three irrigation levels (W1: 85% field capacity (FC), W2: 70% FC, W3: 55% FC) and three salinity levels (S2: 2 g/L, S4: 4 g/L, S6: 6 g/L) were set as nine treatments. In addition, a control treatment (CK: W1, 0 g/L) was added. Each treatment was evaluated and scored by principal component analysis. The results for 2022 and 2023 found the highest scores for CK, W2S2, W3S2 and CK, W2S4, W2S2, respectively. Based on response surface methodology, we constructed composite models of multi-objective demands, whose results indicated that 66-72% FC and 2 g/L salinity were considered the appropriate water-salt combinations for practical production. This paper will be beneficial for maintaining high yield and high quality in tomato production using salty water irrigation.

Knockdown of β-conglycinin α' and α subunits alters seed protein composition and improves salt tolerance in soybean.

Soybean is an important plant source of protein worldwide. Increasing demands for soybean can be met by improving the quality of its seed protein. In this study, GmCG-1, which encodes the β-conglycinin α' subunit, was identified via combined genome-wide association study and transcriptome analysis. We subsequently knocked down GmCG-1 and its paralogues GmCG-2 and GmCG-3 with CRISPR-Cas9 technology and generated two stable multigene knockdown mutants. As a result, the β-conglycinin content decreased, whereas the 11S/7S ratio, total protein content and sulfur-containing amino acid content significantly increased. Surprisingly, the globulin mutant exhibited salt tolerance in both the germination and seedling stages. Little is known about the relationship between seed protein composition and the salt stress response in soybean. Metabonomics and RNA-seq analysis indicated that compared with the WT, the mutant was formed through a pathway that was more similar to that of active salicylic acid biosynthesis; however, the synthesis of cytokinin exhibited greater defects, which could lead to increased expression of plant dehydrin-related salt tolerance proteins and cell membrane ion transporters. Population evolution analysis suggested that GmCG-1, GmCG-2, and GmCG-3 were selected during soybean domestication. The soybean accessions harboring GmCG-1Hap1 presented relatively high 11S/7S ratios and relatively high salt tolerance. In conclusion, knockdown of the β-conglycinin α and α' subunits can improve the nutritional quality of soybean seeds and increase the salt tolerance of soybean plants, providing a strategy for designing soybean varieties with high nutritional value and high salt tolerance.