Regulates Salt Tolerance Research Articles

A Chromosome-Level Genome Sequence Reveals Regulation of Salt Stress Response in Mesembryanthemum crystallinum.

Salt stress disturbs plant growth and photosynthesis due to its toxicity. The ice plant Mesembryanthemum crystallinum is a highly salt-tolerant facultative crassulacean acid metabolism (CAM) plant. However, the genetic basis of the salt tolerance mechanisms in ice plants remains unclear. In this study, we constructed a chromosome-level whole-genome sequence of the ice plant and performed transcriptome analysis of the effects of salt treatment on the leaves. After 24-hour 500 mM NaCl treatment to the roots, 1100 and 1394 genes, including CAM pathway, glycolysis, and inositol metabolism, were up- and down-regulated in the leaves, respectively. Salt treatment also influenced the abscisic acid (ABA) signaling components, including genes from the PYRABACTIN RESISTANCE1 (PYR1) family and the PROTEIN PHOSPHATASE 2CA (PP2CA) family. We detected the induction of the genes encoding various ion transporters after salt treatment. The expression of most v-ATPase subunits is induced, leading to vacuolar acidification, which facilitates sodium ion sequestration in the vacuoles. Additionally, some genes encoding metal ion transporters, including the genes from the ZIP family and NRAMP family, were induced by salt treatment, accompanied by the accumulation of iron, zinc, and copper ions in the leaves. Cis-motif enrichment analysis revealed that ABRE-like motifs and MYB-binding-like motifs were enriched in the upstream sequences of genes that were either up-regulated or down-regulated by salt. In conclusion, this study highlights how salt treatment induces drastic and rapid transcriptomic changes and unveils the ice plant's genomic foundation. Our resources provide further insights into the regulation of salt tolerance in the ice plants.

Comparative transcriptome analysis and functional verification revealed that GhSAP6 negatively regulates salt tolerance in upland cotton.

Owing to the scarcity of cultivable land in China, the agricultural sector is primarily focused on grain and oil crops. Simultaneously, the cultivation of cotton has gradually shifted towards regions characterized by elevated soil salinity levels. Additionally, the mechanism behind cotton's ability to tolerate salt remains elusive. In this study, we identified the Z9807 genotype as highly tolerant to salt stress, exhibiting superior leaf wilting resistance, antioxidant activity, catalase activity, K+/Na+ ratio, and growth compared to the salt-sensitive ZJ0102. Comparative transcriptome analysis revealed marked differences in salt stress responses between Z9807 and ZJ0102. This study identified a considerable number of differentially expressed genes associated with salt tolerance across multiple time points. By integration of QTL and GWAS mapping data, we successfully identified 621 candidate genes associated with salt tolerance. Weighted gene correlation network analysis exhibited three co-expression modules related to salt-tolerant Z9807 samples, ultimately identifying 15 core salt-tolerant candidate genes. We also conducted in-depth research on the salt tolerance of the stress-associated protein (SAP) GhSAP6 (GhSAP6_At and GhSAP6_Dt homologs). Results revealed that these candidate genes may inhibit salt tolerance through Virus-Induced Gene Silencing (VIGS) and transgenic overexpression assays conducted in Arabidopsis thaliana. Furthermore, we used yeast two-hybrid and luciferase assay experiments to confirm the ubiquitin degradation pathway between selected interacting proteins and verified the interaction with RAD23C. This study will provide new insights into the mechanisms related to salt tolerance in upland cotton.

A small peptide miPEP172b encoded by primary transcript of miR172b regulates salt tolerance in rice.

Recent studies have demonstrated that the primary transcript of miRNAs (pri-miRNAs) are able to encode small peptides influencing plant growth and development, as well as responses to various environmental cues. However, their role in plant responses to salt stress is not fully comprehended. Here, we characterized a short peptide encoded by miR172b (miPEP172b) in rice (Oryza sativa L.). By applying synthetic miPEP172b, we observed a significant increase in miR172b abundance and a decrease in the expression of its target gene IDS1. Consequently, plants treated with miPEP172b exhibited enhanced tolerance to salinity stress. Furthermore, we found that miPEP172b was efficiently absorbed by roots and transported to the aerial parts of the plant, thus conferring salt tolerance in the aboveground organs. Overexpression of miPEP172b resulted in reduced levels of reactive oxygen species (ROS), leading to improved performance of rice seedlings under salinity conditions. This was consistent with the observations in miR172-overexpressing plants. Conversely, miPEP172b mutants showed increased sensitivity to salt stress. Further analysis revealed that miPEP172b-miR172-IDS1 improved rice salt tolerance by integrating the ROS scavenging pathway and plant hormone signaling. Our findings highlight the significant role of miPEP172b in regulating miR172 activity and salt tolerance, providing a useful agent for improving crop salt tolerance.

Arabidopsis Ankyrin-Repeat Protein Kinase ANK-PK2 Negatively Regulates Salt Tolerance by Mediating Degradation of the Sugar Transporter Protein STP11.

Soluble sugars provide energy sources required for plant growth and development. They also act as osmoprotectants to improve the salt tolerance of plants. However, molecular mechanism underlying the negative regulation of soluble sugar accumulation in plants under salt stress conditions remains unknown. In this study, we investigated the functions of ankyrin-repeat kinase 2 (ANK-PK2) that regulates soluble sugar content in Arabidopsis under salt stress. ANK-PK2 interacts with and phosphorylates the sugar transporter protein 11 (STP11) under salt stress. Phosphorylated STP11 is easier to degrade, and its glucose-transporting ability and soluble sugar accumulation are inhibited. The ank-pk2 mutant exhibited increased salt tolerance. The salt-sensitive phenotype of the mutant stp11 was recovered through a dephosphorylation mutation that changed Thr227 in STP11 to Ala227. Our results revealed a novel molecular mechanism underlying salt stress adaptation in Arabidopsis, which ANK-PK2 negatively regulates salt tolerance by phosphorylating and subsequently decreasing the transport activity of STP11 to balance the cellular soluble sugar content in Arabidopsis.

A Series of Novel Alleles of Ehd2 Modulating Heading and Salt Tolerance in Rice.

Rice (Oryza sativa L.) is a staple crop for nearly half of the global population and one of China's most extensively cultivated cereals. Heading date, a critical agronomic trait, determines the regional and seasonal adaptability of rice varieties. In this study, a series of mutants (elh5 to elh12) exhibiting extremely late heading under both long-day (LD) and short-day (SD) conditions were identified from an ethyl methanesulfonate (EMS) mutant library. Using MutMap and map-based cloning, the causative gene was identified as a novel allele of Ehd2/OsID1/RID1/Ghd10. Functional validation through CRISPR/Cas9 knockout and complementation assays confirmed its role in regulating heading. The elh6 mutation was found to cause intron retention due to alternative splicing. Ehd2 encodes a Cys-2/His-2-type zinc finger transcription factor with an IDD domain and transcriptional activity in yeast. Its expression peaks in developing leaves before heading and spikes during reproductive conversion. In elh6 mutants, delayed heading resulted from downregulating the Ehd1-Hd3a pathway genes. Salinity stress significantly hampers rice growth and productivity. Transcriptomic analysis of elh10 and ZH8015 seedlings exposed to salt stress for 24 h identified 5150 differentially expressed genes (DEGs) at the seedling stage, predominantly linked to stress response pathways. Ehd2 was revealed as a modulator of salt tolerance, likely through the regulation of ion transport, enzyme activity, and antioxidant systems. This study establishes Ehd2 as a pivotal factor in promoting heading while negatively regulating salt tolerance in rice.

LbHKT1;1 Negatively Regulates Salt Tolerance of Limonium bicolor by Decreasing Salt Secretion Rate of Salt Glands.

The HKT-type proteins have been extensively studied and have been shown to play important roles in long-distance Na+ transport, maintaining ion homoeostasis and improving salt tolerance in plants. However, there have been no reports on the types, characteristics and functions of HKT-type proteins in Limonium bicolor, a recretohalophyte species with the typical salt gland structure. In this study, five LbHKT genes were identified in L. bicolor, all belonging to subfamily 1 (HKT1). There are many cis-acting elements related to abiotic/biotic stress response on the promoters of the LbHKT genes. LbHKT1;1 was investigated in detail. Subcellular localization results showed that LbHKT1;1 is targeted to the plasma membrane. Functional analysis in yeast showed that LbHKT1;1 has a higher tolerance than AtHKT1;1 under high Na+ conditions. Silencing and overexpression of the LbHKT1;1 gene in L. bicolor showed that LbHKT1;1 negatively regulates salt secretion by the salt glands. Further experiments showed that LbbZIP52 can specifically bind to the ABRE element in the LbHKT1;1 promoter and regulate the expression of the LbHKT1;1 gene and is involved in the negative regulation of the salt secretion capacity of L. bicolor. This study demonstrates for the first time that the HKT-type protein is involved in salt secretion by salt glands and provides a new perspective on the function of HKT-type proteins under salt stress conditions.

AozC, a zn(II)2Cys6 transcription factor, negatively regulates salt tolerance in Aspergillus oryzae by controlling fatty acid biosynthesis

BackgroundIn the soy sauce fermentation industry, Aspergillus oryzae (A. oryzae) plays an essential role and is frequently subjected to high salinity levels, which pose a significant osmotic stress. This environmental challenge necessitates the activation of stress response mechanisms within the fungus. The Zn(II)2Cys6 family of transcription factors, known for their zinc binuclear cluster-containing proteins, are key regulators in fungi, modulating various cellular functions such as stress adaptation and metabolic pathways.ResultsOverexpression of AozC decreased growth rates in the presence of salt, while its knockdown enhanced growth, the number of spores, and biomass, particularly under conditions of 15% salt concentration, doubling these metrics compared to the wild type. Conversely, the knockdown of AozC via RNA interference significantly enhanced spore density and dry biomass, particularly under 15% salt stress, where these parameters were markedly improved over the wild type strain. Moreover, the overexpression of AozC led to a downregulation of the FAD2 gene, a pivotal enzyme in the biosynthesis of unsaturated fatty acids (UFAs), which are essential for preserving cell membrane fluidity and integrity under saline conditions. Transcriptome profiling further exposed the influence of AozC on the regulation of UFA biosynthesis and the modulation of critical stress response pathways. Notably, the regulatory role of AozC in the mitogen-activated protein kinase (MAPK) signaling and ABC transporters pathways was highlighted, underscoring its significance in cellular osmotic balance and endoplasmic reticulum homeostasis. These findings collectively indicate that AozC functions as a negative regulator of salt tolerance in A. oryzae.ConclusionThis research suggest that AozC acts as a negative regulator in salt tolerance and modulates fatty acid biosynthesis in response to osmotic stress. These results provide insights into the regulatory mechanisms of stress adaptation in A. oryzae.

C2H2 Zinc Finger Protein Family Analysis of Rosa rugosa Identified a Salt-Tolerance Regulator, RrC2H2-8.

Rosa rugosa is a representative aromatic species. Wild roses are known for their strong tolerance to highly salty environments, whereas cultivated varieties of roses exhibit lower salt stress tolerance, limiting their development and industrial expansion. Previous studies have shown that C2H2-type zinc finger proteins play a crucial role in plants' resistance to abiotic stresses. In this study, 102 C2H2-type zinc finger genes (RrC2H2s) were identified in R. rugosa via a comprehensive approach. These genes were categorized into three lineages, and their motif constitutions were grouped into four classes. RrC2H2s were distributed across all seven rose chromosomes, with 15 paralogous gene pairs identified within synteny regions. Additionally, 43 RrC2H2s showed differential expression across various tissues under salt stress, with RrC2H2-8 being the only gene consistently repressed in all tissues. Subcellular localization analysis revealed that the RrC2H2-8 protein was localized in the nucleus. The heterologous expression of RrC2H2-8 in Arabidopsis significantly improved its growth under salt stress compared to the wild-type (WT) plants. Furthermore, the malondialdehyde content in the roots of transgenic Arabidopsis was significantly lower than that in the WT, suggesting that RrC2H2-8 enhanced salt tolerance by reducing cellular damage. This study provides a systematic understanding of the RrC2H2 family and identifies RrC2H2-8 as a regulator of salt tolerance, laying a foundation for future research on the mechanisms of salt stress regulation by RrC2H2.

CALMODULIN-BINDING RECEPTOR-LIKE CYTOPLASMIC KINASE 3 regulates salt tolerance through CATALASE 2 in Arabidopsis.

Soil salinization threatens global crop production. Here, we report that a receptor-like cytoplasmic kinase (RLCK), CALMODULIN-BINDING RECEPTOR-LIKE CYTOPLASMIC KINASE 3 (CRCK3), plays an essential role in plant salt tolerance via CATALASE 2 (CAT2), a hydrogen peroxide (H2O2)-scavenging enzyme in Arabidopsis (Arabidopsis thaliana). CRCK3 was induced by salt stress, and its knockout mutant displayed a salt-sensitive phenotype compared to wild-type (WT) plants. CRCK3 was activated by salt stress in a calcium-dependent manner, and its kinase activity was required for plant salt tolerance. CRCK3 physically interacted with CAT2, and CRCK3-mediated salt tolerance depended on CAT2. Salt treatment significantly induced CAT2 phosphorylation via the action of CRCK3, and this phosphorylation was required for CAT2-mediated H2O2 scavenging to reduce ROS content and oxidative damage in plants under saline conditions. CRCK3 phosphorylated CAT2 at the Thr209 residue, resulting in elevated catalase activity to reduce reactive oxygen species (ROS) accumulation under saline conditions. Therefore, the CRCK3-CAT2 module mediates plant salt tolerance by maintaining redox homeostasis. This study expands our knowledge of how plants respond to salt stress.

SOS3-3 Enhances the Salt Tolerance of Tomato Plants by Regulating ROS Balance

Salt stress affects the growth, metabolism, yield, and quality of crops. To adapt to high-salt environments, plants form various regulatory mechanisms. Salt over sensitive (SOS) is the key gene of SOS signal transduction pathway. As a member of the SOS3 subfamily, the function of SOS3-3 under salt stress has not been reported. To verify the function of SOS3-3 and the morphological and physiological parameters, the expression of genes related to stress were compared between the SOS3-3 overexpressed (OESOS3-3) and silenced tomato (VSOS3-3) at control and 10 days’ NaCl treatment. The results showed that, compared with the control (Ve), the plants of VSOS3-3 were shorter under salt stress, with curled leaves and abscission. The fresh and dry weights, Fv/Fm, total chlorophyll content, antioxidant enzyme activities, and proline content of VSOS3-3 significantly decreased, while the relative conductivity, hydrogen peroxide (H2O2), and Malondialdehyde (MDA) content of VSOS3-3 plants significantly increased compared to that of WT, respectively. Compared to the wild-type (WT), OESOS3-3 plants were less damaged by salt stress, with significantly higher plant height, fresh and dry weights, Fv/Fm, total chlorophyll content, antioxidant enzyme activity, and proline content. However, the relative conductance, H2O2, and MDA content were significantly lower in OESOS3-3 than WT. The expression levels of SOS1, SOS2, LKT1 (ion transport-related gene), APX1 (ROS signaling pathway-related gene), P5CS (osmoregulation-related gene), and ABF4 (ABA signaling pathway-related gene) were significantly lower in VSOS3-3 than Ve, but significantly higher in OESOS3-3 than in WT. These results suggested that SOS3-3 regulate salt tolerance by influencing physiological and biochemical changes and the expression of genes related to stress response. This study revealed the mechanism of SOS family participating in regulating tomato salt tolerance, providing a theoretical basis for improving tomato salt tolerance.

Genome-wide characterization of Solanum tuberosum UGT gene family and functional analysis of StUGT178 in salt tolerance

UDP-glycosyltransferases (UGTs) widely exist in plants and play essential roles in catalyzing the glycosylation reaction associated with metabolic processes. UGT gene family has been identified in many species to date. However, the comprehensive identification and systematic analysis have not been documented yet in the latest potato genome. In this study, a total of 295 UGT members (StUGT) were identified and found to be unevenly distributed on twelve chromosomes of potato. All StUGT genes were classified into 17 groups (A-P, R) and the UGT genes within the same groups have similar structural characterization. Tandem duplication was the major driving force for the StUGT gene expansion. The prediction of cis-acting elements showed that the development process, light, phytohormone, and abiotic stress-responsive elements generally existed in StUGT promoter regions. Analysis of spatial and temporal expression patterns demonstrated that StUGT genes were widely and differentially expressed in various tissues. Additionally, to investigate the salt stress-responsive genes, we analyzed the expression profiles of the StUGT genes under salt treatment. A total of 50 and 20 StUGT genes were continuously up- and down-regulated, respectively, implicating that these genes were involved in the regulation of salt tolerance. Among them, the StUGT178 gene, which was significantly induced by salt stress and contains salt-responsive element, was considered as one of the most relevant candidate genes. Transient transformation of the StUGT178 promoter in tobacco revealed that the transcriptional activation activity of the StUGT178 gene was strengthened under salt treatment. Furthermore, the heterologous expressions of the promoter and coding protein of the StUGT178 gene in Arabidopsis further demonstrated that the StUGT178 gene significantly responds to salt treatment, and enhanced salinity tolerance by regulating antioxidant enzyme activity and H2O2 accumulation. These results provide comprehensive information for a better understanding of the StUGT genes and offer a foundation for uncovering their function associated with salt stress in potato.

Transcription factors CpSPL5 and CpSPL8 negatively regulate salt tolerance in Codonopsis pilosula by inhibiting SOS pathway.

Environmental stresses such as salt and drought severely affect plant growth and development. SQUAMOSA-promoter binding protein-like (SPL) transcription factors (TFs) play critical roles in the regulation of diverse processes; however, reports describing the SPL regulation of plant responses to abiotic stress are relatively few. In this study, two stress-responsive TFs from Codonopsis pilosula (CpSPL5 and CpSPL8) are reported, which confer salt stress sensitivity. CpSPL5 and CpSPL8 are expressed in almost all tissues and localized in the nucleus, where the CpSPL5 transcript level is relatively higher than that of CpSPL8. Their expression levels are significantly suppressed in hairy roots treated with ABA, NaCl, PEG-6000, and under high temperature stress. Compared with the control, CpSPL5, or CpSPL8-overexpressed hairy roots increased salt stress sensitivity, and exhibited higher levels of O2- and MDA, as well as lower superoxide dismutase and peroxidase activities. Further, the CpSPL5 or CpSPL8 interference transgenic hairy roots enhanced salt tolerance and exhibited contrasting phenotype and antioxidant indices. Although all genotypes revealed significantly increased Na+ and decreased K+ contents under salt stress, the physiological indicators of CpSPL5 or CpSPL8-interference transgenic hairy roots could be partially restored, where CpSPL5 was more sensitive to salt stress than CpSPL8. A yeast one-hybrid and dual-luciferase assay revealed that CpSPL5 and CpSPL8 directly targeted and inhibited the expression of CpSOS2 in the salt overly sensitive (SOS) pathway, which promoted salt stress sensitivity. Our findings suggest that CpSPL5 and CpSPL8 served as negative regulators of salt tolerance, which indicate that members of the SPL family participate in the plant SOS pathway.

OsCaM1-1 Is Responsible for Salt Tolerance by Regulating Na+/K+ Homoeostasis in Rice.

Calmodulin, a highly conserved calcium-binding protein, plays a crucial role in response to salt stress. Previous studies investigated sequence and function of calmodulin members in some plants, but their roles in rice have not been fully elucidated. Three OsCaM1 genes namely OsCaM1-1/2/3 encode the same OsCaM1 protein. Here, we found that OsCaM1-1 had significantly higher expression than the other two genes under salt stress. After 4 weeks of exposure to 75 mM NaCl, OsCaM1-1 overexpressed mutants showed higher salt tolerance, while knocked-out mutants exhibited lower salt tolerance, compared to the wild type. Moreover, the oscam1-1 mutants had higher Na+ concentration and Na+/K+ ratio in both shoots and roots, less instantaneous K+ and Ca2+ fluxes in roots, compared to wild type under salt stress, indicating the involvement of OsCaM1-1 in regulation of Na+ and K+ homoeostasis via Ca2+ signal. RNA-seq analysis identified 452 differentially expressed genes (DEGs) regulated by OsCaM1-1 and salt stress, and they were mainly enriched in nucleus DNA-binding activities, including ABI5, WRKY76, WRKY48 and bHLH120 transcription factors. Knockout of OsCaM1-1 also modulated the expression of Na+ transporters, including HKT1;1, HKT1;5, SOS1, NHX1 and NHX4. In conclusion, OsCaM1-1 positively regulates salt tolerance in rice through mediating ion homoeostasis.

Salt tolerance candidate genes identified by QTL mapping, RNA-seq, and functional analysis in tilapia

Salt tolerance in fish is crucial for aquaculture as it enhances survival and productivity in varying salinity conditions, thus expanding the range of viable farming environments and improving economic sustainability. Through QTL mapping and GWAS in a hybrid F2 family of Mozambique and Nile tilapia, two large-effect QTL on chromosomes 11 and 18 were identified respectively. These two QTL explained a total of 39.9 % of the phenotypic variance. The identification of a QTL on LG11 suggests the presence of a previously unrecognized genetic factor contributing to salt tolerance. Comparative transcriptomic analysis of gill and kidney tissues between susceptible and tolerant tilapias highlights the importance of osmotic balance in regulation of salt tolerance in tilapia. Integration of QTL and RNA-seq data identified two candidate genes: acyl-coenzyme A thioesterase 5 (acot5) and sodium- and chloride-dependent taurine transporter (slc6a6) likely playing critical roles in such process. Functional analysis showed that over-expressing acot5 or slc6a6 in grouper kidney cells increased viability under salt stress by 4.46 % and 17.53 %, respectively. Subcellular localization revealed nuclear presence of ACOT5 and stress-induced nuclear translocation of SLC6A6. These findings highlight acot5 and slc6a6 as candidates for genetic manipulation and selection to enhance salt tolerance in tilapia, guiding genetic improvement efforts and promoting sustainable practices.

PdbCRF5 Overexpression Negatively Regulates Salt Tolerance by Downregulating PdbbZIP61 to Mediate Reactive Oxygen Species Scavenging and ABA Synthesis in Populus davidiana × P. bolleana.

Salt stress is the main factor limiting the large-scale cultivation of Shanxin poplar; therefore, improving its salt tolerance is crucial. In this study, we identified and characterized a CRF gene (PdbCRF5) in Shanxin poplar. Compared with the wild-type poplar, the Shanxin poplar overexpressing PdbCRF5 were more sensitive to salt stress. The PdbCRF5-silenced plants exhibited improved salt tolerance. ChIP‒PCR, EMSA, and Y1H confirmed that PdbCRF5 can regulate the expression of the PdbbZIP61 by binding to ABRE element. Further analysis revealed that the overexpression of PdbbZIP61 can reduce cell damage by increasing ROS scavenging, and on the other hand, overexpression of PdbbZIP61 can improve the salt tolerance of Shanxin poplar by regulating the expression of the PdbNCED genes to increase the ABA content. In addition, we also demonstrated that PdbCRF5 can inhibit the expression of the PdbbZIP61 in combination with PdbCRF6. The overexpression of PdbCRF6 also reduced the salt tolerance of Shanxin poplar. Therefore, we found that PdbCRF5 negatively regulates the salt tolerance of Shanxin poplar by inhibiting the PdbbZIP61, indicating that PdbCRF5 plays an important role in the tolerance of Shanxin poplar to salt stress and is an important candidate gene for gene editing and breeding in forest trees.

Genome-wide identification of m6A-related gene family and the involvement of TdFIP37 in salt stress in wild emmer wheat.

The genomic organization, phylogenetic relationship, expression patterns, and genetic variations of m6A-related genes were systematically investigated in wild emmer wheat and the function of TdFIP37 regulating salt tolerance was preliminarily determined. m6A modification is one of the most abundant and crucial RNA modifications in eukaryotics, playing the indispensable role in growth and development as well as stress response in plants. However, its significance in wild emmer wheat remains elusive. Here, a genome-wide search of m6A-related genes was conducted in wild emmer wheat to obtain 64 candidates, including 21 writers, 17 erasers, and 26 readers. Phylogenetic and collinearity analysis demonstrated that segmental duplication and polyploidization contributed mainly to the expansion of m6A-related genes in wild emmer. A number of cis-acting elements involving in stress and hormonal regulation were found in the promoter regions of them, such as MBS, LTR, and ABRE. Genetic variation of them was also investigated using resequencing data and obvious genetic bottleneck was occurred on them during wild emmer wheat domestication process. Furthermore, the salt-responsive candidates were investigated through RNA-seq data and qRT-PCR validation using the salt-tolerant and -sensitive genotypes and the co-expression analysis showed that they played the hub role in regulating salt stress response. Finally, the loss-function mutant of Tdfip37 displayed the significantly higher salt-sensitive compared to WT and then RNA-seq analysis demonstrated that FIP37 mediated the MAPK pathway, hormone signal transduction, as well as transcription factor to regulate salt tolerance. This study provided the potential m6A genes for functional analysis, which will contribute to better understand the regulatory roles of m6A modification and also improve the salt tolerance from the perspective of epigenetic approach in emmer wheat and other crops.

ABCG Transporters in the Adaptation of Rice to Salt Stresses

The ATP-binding cassette (ABC) proteins are a diverse family of transmembrane transporter proteins widely identified in various organisms. The ABCG transporters belong to the G subfamily of the ABC transporter family. Rarely research on ABCG transporters involved in salt tolerance of rice was found. In this study, the evolutionary relationships, conserved motifs, intra- and inter-species homologous genes, and cis-acting elements of ABCG subfamily members were analyzed, and the expression changes of these genes under salt stress at 0 h, 3 h, and 24 h were detected. Based on these results, the candidate gene OsABCG7, which is induced by salt stress, was selected for further studies. Yeast experiments confirmed that the OsABCG7 gene might be involved in the regulation of salt tolerance. The abcg7 mutant showed a higher degree of leaf wilting and a lower survival rate, exhibiting a salt-sensitive phenotype. Systematic analysis of this family in rice helps design effective functional analysis strategies and provides data support for understanding the role of ABCG transporters under salt stress.

The transcription factor ZmNAC84 increases maize salt tolerance by regulating ZmCAT1 expression

Salt stress severely affects plant growth and yield. The transcription factor NAC plays a variety of important roles in plant abiotic stress, but we know relatively little about the specific molecular mechanisms of NAC in antioxidant defense. Here, our genetic studies reveal the positive regulation of salt tolerance in maize by the transcription factor ZmNAC84. Under salt stress, overexpression of ZmNAC84 in maize increased the expression of ZmCAT1, enhanced CAT activity, and consequently reduced H2O2 accumulation, thereby improving salt stress tolerance in maize. Whereas RNA interference-mediated knockdown of ZmNAC84 produced the opposite effect. Subsequently, we found that ZmNAC84 directly binds to and regulates the expression of the ZmCAT1 promoter, and the hybridized material also demonstrated that ZmCAT1 is a downstream target gene of ZmNAC84. In addition, phenotypic and biochemical analyses indicated that ZmCAT1 positively regulated salt tolerance by regulating H2O2 accumulation under salt stress. Taken together, these results reveal the function of ZmNAC84 in regulating ZmCAT1-mediated antioxidant defense in response to salt stress in plants.

Salt-responsive miRNA-SSR markers from Dongxiang wild rice: characterization and potential application in exploring salt-tolerant genetic resources

Abstract MicroRNAs (miRNAs) play important roles in regulating salt tolerance in Dongxiang wild rice (DXWR, Oryza rufipogon Griff.). The development of salt-responsive miRNA-simple sequence repeat (SSR) markers will significantly bolster research on DXWR, providing novel tools for exploring salt-tolerant genetic resources and advancing the development of salt-tolerant rice varieties. In the present study, a total of 137 miRNA-SSR markers were successfully developed, specifically derived from miRNAs responsive to salt stress in DXWR. Subsequently, a subset of 20 markers was randomly selected for validation across three distinct DXWR populations, along with 35 modern rice varieties. Notably, 13 of these markers exhibited remarkable polymorphism. The polymorphic markers collectively amplified 52 SSR loci, averaging four alleles per locus. The polymorphism information content values associated with these loci spanned from 0.23 to 0.70, with a mean value of 0.49. Particularly noteworthy is the miR162a-SSR marker, which demonstrated distinct allelic patterns and holds potential as a diagnostic marker for discriminating the salt-tolerant rice varieties from the non-tolerant varieties. This study provides a valuable tool for genetic analysis and precision breeding, facilitating the identification and utilization of valuable salt-tolerant genetic resources.

The MdCo gene encodes a putative 2OG-Fe (II) oxygenase that positively regulates salt tolerance in transgenic tomato and apple

Salinity stress is a significant environmental factor that impacts the growth, development, quality, and yield of crops. The 2OG-Fe (II) oxygenase family of enzyme proteins plays crucial roles in plant growth and stress responses. Previously, we identified and characterized MdCo, which encodes a putative 2OG-Fe (II) oxygenase, a key gene for controlling the columnar growth habit of apples. In this study, we explored the role of MdCo in salt stress tolerance. Expression analysis suggested that MdCo exhibits high expression in roots and is significantly induced by NaCl stress. Ectopic expression of MdCo exhibited enhanced salt stress tolerance in transgenic tomatoes, and these plants were characterized by better growth performance, and higher chlorophyll content, but lower electrolyte leakage and malondialdehyde (MDA), and less hydrogen peroxide (H2O2) and superoxide radicals (O2-) under salt stress. Overexpression of MdCo can effectively scavenge reactive oxygen species (ROS) by enhancing the activities of antioxidant enzymes and up-regulating the expression of stress-associated genes under salt stress, thereby enhancing salt tolerance in apple calli. Collectively, these findings provide new insights into the function of MdCo in salt stress tolerance as well as future potential application for apple breeding aimed at improving salt stress tolerance.