Green Synthesis of Carbon Quantum Dots and Carbon Quantum Dot-Gold Nanoparticles for Applications in Bacterial Imaging and Catalytic Reduction of Aromatic Nitro Compounds.

This study delves into the green synthesis and multifaceted applications of three types of carbon quantum dots (CQDs), namely, CQDs-1, CQDs-2, and CQDs-3. These CQDs were innovatively produced through a gentle pyrolysis process from distinct plant-based precursors: genipin with glucose for CQDs-1, genipin with extracted gardenia seeds for CQDs-2, and genipin with whole gardenia seeds for CQDs-3. Advanced analytical techniques, including X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR), were employed to detail the CQDs' structural and surface characteristics, revealing their unique functional groups and surface chemistries. The study further explores the CQDs' bioimaging potential, where confocal fluorescence microscopy evidenced their swift uptake by Escherichia coli bacteria, indicating their suitability for bacterial imaging. These CQDs were also applied in the synthesis of gold nanoparticles (AuNPs), acting as reducing agents and stabilizers. Among these, CQD3-AuNPs were distinguished by their remarkable stability and catalytic efficiency, achieving a 99.7% reduction of 4-nitrophenol to 4-aminophenol in just 10 min and maintaining near-complete reduction efficiency (99.6%) after 60 days. This performance notably surpasses that of AuNPs synthesized using sodium citrate, underscoring the exceptional capabilities of CQD3-AuNPs. These insights pave the way for leveraging CQDs and CQD-stabilized AuNPs in bacterial imaging and catalysis, presenting valuable directions for future scientific inquiry and practical applications.

The elite haplotype OsGATA8-H coordinates nitrogen uptake and productive tiller formation in rice.

Excessive nitrogen promotes the formation of nonproductive tillers in rice, which decreases nitrogen use efficiency (NUE). Developing high-NUE rice cultivars through balancing nitrogen uptake and the formation of productive tillers remains a long-standing challenge, yet how these two processes are coordinated in rice remains elusive. Here we identify the transcription factor OsGATA8 as a key coordinator of nitrogen uptake and tiller formation in rice. OsGATA8 negatively regulates nitrogen uptake by repressing transcription of the ammonium transporter gene OsAMT3.2. Meanwhile, it promotes tiller formation by repressing the transcription of OsTCP19, a negative modulator of tillering. We identify OsGATA8-H as a high-NUE haplotype with enhanced nitrogen uptake and a higher proportion of productive tillers. The geographical distribution of OsGATA8-H and its frequency change in historical accessions suggest its adaption to the fertile soil. Overall, this study provides molecular and evolutionary insights into the regulation of NUE and facilitates the breeding of rice cultivars with higher NUE.

Edwardsiella tarda Attenuates Virulence upon Oxytetracycline Resistance.

The relationship between antibiotic resistance and bacterial virulence has not yet been fully explored. Here, we use Edwardsiella tarda as the research model to investigate the proteomic change upon oxytetracycline resistance (LTB4-ROTC). Compared to oxytetracycline-sensitive E. tarda (LTB4-S), LTB4-ROTC has 234 differentially expressed proteins, of which the abundance of 84 proteins is downregulated and 15 proteins are enriched to the Type III secretion system, Type VI secretion system, and flagellum pathways. Functional analysis confirms virulent phenotypes, including autoaggregation, biofilm formation, hemolysis, swimming, and swarming, are impaired in LTB4-ROTC. Furthermore, the in vivo bacterial challenge in both tilapia and zebrafish infection models suggests that the virulence of LTB4-ROTC is attenuated. Analysis of immune gene expression shows that LTB4-ROTC induces a stronger immune response in the spleen but a weaker response in the head kidney than that induced by LTB4-S, suggesting it's a potential vaccine candidate. Zebrafish and tilapia were challenged with a sublethal dose of LTB4-ROTC as a live vaccine followed by LTB4-S challenge. The relative percentage of survival of zebrafish is 60% and that of tilapia is 75% after vaccination. Thus, our study suggests that bacteria that acquire antibiotic resistance may attenuate virulence, which can be explored as a potential live vaccine to tackle bacterial infection in aquaculture.

α-Ketoglutarate downregulates thiosulphate metabolism to enhance antibiotic killing.

Potentiation of the effects of currently available antibiotics is urgently required to tackle the rising antibiotics resistance. The pyruvate (P) cycle has been shown to play a critical role in mediating aminoglycoside antibiotic killing, but the mechanism remains unexplored. In this study, we investigated the effects of intermediate metabolites of the P cycle regarding the potentiation of gentamicin. We found that α-ketoglutarate (α-KG) has the best synergy with gentamicin compared to the other metabolites. This synergistic killing effect was more effective with aminoglycosides than other types of antibiotics, and it was effective against various types of bacterial pathogens. Using fish and mouse infection models, we confirmed that the synergistic killing effect occurred in vivo. Furthermore, functional proteomics showed that α-KG downregulated thiosulphate metabolism. Upregulation of thiosulphate metabolism by exogenous thiosulphate counteracted the killing effect of gentamicin. The role of thiosulphate metabolism in antibiotic resistance was further confirmed using thiosulphate reductase knockout mutants. These mutants were more sensitive to gentamicin killing, and less tolerant to antibiotics compared to their parental strain. Thus, our study highlights a strategy for potentiating antibiotic killing by using a metabolite that reduces antibiotic resistance.

CEPs suppress auxin signaling but promote cytokinin signaling to inhibit root growth in Arabidopsis.

C-terminally encoded peptides (CEPs) are peptide hormones that function as mobile signals coordinating crucial developmental programs in plants. Previous studies have revealed that CEPs exert negative regulation on root development through interaction with CEP receptors (CEPRs), CEP DOWNSTREAMs (CEPDs), the cytokinin receptor ARABIDOPSIS HISTIDINE KINASE (AHKs) and the transcriptional repressor Auxin/Indole-3-Acetic Acid (AUX/IAA). However, the precise molecular mechanisms underlying CEPs-mediated regulation of root development via auxin and cytokinin signaling pathways still necessitate further detailed investigation. In this study, we examined prior research and elucidated the underlying molecular mechanisms. The results showed that both synthetic AtCEPs and overexpression of AtCEP5 markedly supressed primary root elongation and lateral root (LR) formation in Arabidopsis. Molecular biology and genetics elucidated how CEPs inhibit root growth by suppressing auxin signaling while promoting cytokinin signaling. In summary, this study elucidated the inhibitory effects of AtCEPs on Arabidopsis root growth and provided insights into their potential molecular mechanisms, thus enhancing our comprehension of CEP-mediated regulation of plant growth and development.

The beneficial rhizobacterium Bacillus velezensis SQR9 regulates plant nitrogen uptake via an endogenous signaling pathway.

Nitrogen fertilizer is widely used in agriculture to boost crop yields. Plant growth-promoting rhizobacteria (PGPRs) can increase plant nitrogen use efficiency through nitrogen fixation and organic nitrogen mineralization. However, it is not known whether they can activate plant nitrogen uptake. In this study, we investigated the effects of volatile compounds (VCs) emitted by the PGPR strain Bacillus velezensis SQR9 on plant nitrogen uptake. Strain SQR9 VCs promoted nitrogen accumulation in both rice and Arabidopsis. In addition, isotope labeling experiments showed that strain SQR9 VCs promoted the absorption of nitrate and ammonium. Several key nitrogen-uptake genes were up-regulated by strain SQR9 VCs, such as AtNRT2.1 in Arabidopsis and OsNAR2.1, OsNRT2.3a, and OsAMT1 family members in rice, and the deletion of these genes compromised the promoting effect of strain SQR9 VCs on plant nitrogen absorption. Furthermore, calcium and the transcription factor NIN-LIKE PROTEIN 7 play an important role in nitrate uptake promoted by strain SQR9 VCs. Taken together, our results indicate that PGPRs can promote nitrogen uptake through regulating plant endogenous signaling and nitrogen transport pathways.

A root cap-localized NAC transcription factor controls root halotropic response to salt stress in Arabidopsis.

Plants are capable of altering root growth direction to curtail exposure to a saline environment (termed halotropism). The root cap that surrounds root tip meristematic stem cells plays crucial roles in perceiving and responding to environmental stimuli. However, how the root cap mediates root halotropism remains undetermined. Here, we identified a root cap-localized NAC transcription factor, SOMBRERO (SMB), that is required for root halotropism. Its effect on root halotropism is attributable to the establishment of asymmetric auxin distribution in the lateral root cap (LRC) rather than to the alteration of cellular sodium equilibrium or amyloplast statoliths. Furthermore, SMB is essential for basal expression of the auxin influx carrier gene AUX1 in LRC and for auxin redistribution in a spatiotemporally-regulated manner, thereby leading to directional bending of roots away from higher salinity. Our findings uncover an SMB-AUX1-auxin module linking the role of the root cap to the activation of root halotropism.

Compliance with Australian Orthopaedic Association guidelines does not reduce the risk of venous thromboembolism after total hip and knee arthroplasty.

Preventing avoidable venous-thrombo-embolism (VTE) is a priority to improve patient and service outcomes after total hip and total knee arthroplasty (THA, TKA), but compliance with relevant clinical guidelines varies. This study aims to determine the degree to which prophylaxis was compliant with Australian Orthopaedic Association (AOA) VTE prophylaxis guidelines and whether non-compliance is associated with increased risk of VTE. A prospective multi-centre cohort study of adults with osteoarthritis undergoing primary TKA/THA was completed at 19 high-volume public and private hospitals. Data were collected prior to surgery and for one-year post-surgery. Logistic regression was undertaken to explore associations between non-compliance with AOA VTE prophylaxis guidelines and symptomatic 90-day VTE outcomes. Data were analysed for 1838 participants from 19 sites. The rate of non-compliance with all clinical guideline recommendations was 20.1% (N = 369), with 14.1% (N = 259) non-compliance for risk-stratified prophylaxis, 35.8% (N = 658) for duration, and 67.8% (N = 1246) for other general recommendations. Symptomatic VTE was experienced up to 90-days post-surgery by 48 people (2.6%). Overall guideline non-compliance (AOR = 0.93, 95%CI = 0.4 to 1.3, p = 0.86) was not associated with a lower risk of symptomatic 90-day VTE. Results were consistent when people with high bleeding risk were excluded (AOR = 0.94, 95%CI = 0.44 to 2.34, p = 0.89). Non-compliance with the AOA VTE prophylaxis guidelines was not associated with risk of 90-day VTE after arthroplasty. This counterintuitive finding is concerning and necessitates a rigorous review of the AOA VTE prevention clinical guideline.

Trichoderma-secreted anthranilic acid promotes lateral root development via auxin signaling and RBOHF-induced endodermal cell wall remodeling.

Trichoderma spp. have evolved the capacity to communicate with plants by producing various secondary metabolites (SMs). Nonhormonal SMs play important roles in plant root development, while specific SMs from rhizosphere microbes and their underlying mechanisms to control plant root branching are still largely unknown. In this study, a compound, anthranilic acid (2-AA), is identified from T. guizhouense NJAU4742 to promote lateral root development. Further studies demonstrate that 2-AA positively regulates auxin signaling and transport in the canonical auxin pathway. 2-AA also partly rescues the lateral root numbers of CASP1pro:shy2-2, which regulates endodermal cell wall remodeling via an RBOHF-induced reactive oxygen species burst. In addition, our work reports another role for microbial 2-AA in the regulation of lateral root development, which is different from its better-known role in plant indole-3-acetic acid biosynthesis. In summary, this study identifies 2-AA from T. guizhouense NJAU4742, which plays versatile roles in regulating plant root development.

Longitudinal symptom profile of palliative care patients receiving a nurse-led end-of-life (PEACH) programme to support preference to die at home.

OBJECTIVES: Tailored models of home-based palliative care aimed to support death at home, should also ensure optimal symptom control. This study aimed to explore symptom occurrence and distress over time in Palliative Extended And Care at Home (PEACH) model of care recipients. DESIGN: This was a prospective cohort study. SETTING AND PARTICIPANTS: Participants were consecutive recipients of the PEACH rapid response nurse-led model of care in metropolitan Sydney (December 2013-January 2017) who were in the last weeks of life with a terminal or deteriorating phase of illness and had a preference to be cared or die at home. OUTCOME MEASURES: Deidentified data including sociodemographic and clinical characteristics, and symptom distress scores (Symptom Assessment Score) were collected at each clinical visit. Descriptive statistics and forward selection logistic regression analysis were used to explore influence of symptom distress levels on mode of separation ((1) died at home while still receiving a PEACH package, (2) admitted to a hospital or an inpatient palliative care unit or (3) discharged from the package (alive and no longer requiring PEACH)) across four symptom distress level categories. RESULTS: 1754 consecutive clients received a PEACH package (mean age 70 years, 55% male). 75.7% (n=1327) had a home death, 13.5% (n=237) were admitted and 10.8% (n=190) were still alive and residing at home when the package ceased. Mean symptom distress scores improved from baseline to final scores in the three groups (p<0.0001). The frequency of no symptom distress score (0) category was higher in the home death group. Higher scores for nausea, fatigue, insomnia and bowel problems were independent predictors of who was admitted. CONCLUSION: Tailored home-based palliative care models to meet preference to die at home, achieve this while maintaining symptom control. A focus on particular symptoms may further optimise these models of care.

Signal communication during microbial modulation of root system architecture.

Every living organism on Earth depends on its interactions with other organisms. In the rhizosphere, plants and microorganisms constantly exchange signals and influence each other's behavior. Recent studies have shown that many beneficial rhizosphere microbes can produce specific signaling molecules that affect plant root architecture and therefore could have substantial effects on above-ground growth. This review examines these chemical signals and summarizes their mechanisms of action, with the aim of enhancing our understanding of plant-microbe interactions and providing references for the comprehensive development and utilization of these active components in agricultural production. In addition, we highlight future research directions and challenges, such as searching for microbial signals to induce primary root development.

Examining the Role of GLU/GABA to GLN Metabolic Cycle in the Pathogenesis of Post-Stroke Depressive Disorder and Insomnia.

Objective: This study aims to elucidate the potential links between the GLU/GABA to GLN metabolic cycle disruptions and the onset of depressive and insomnia disorders following a stroke. We particularly focus on understanding if these disorders share a common underlying pathogenic mechanism. Methods: We examined 63 patients with post-stroke insomnia, 62 patients with post-stroke depression, and 18 healthy individuals. The study involved assessing insomnia using the Acute Insomnia Scale (AIS) and depression using the Hamilton Depression Rating Scale. We measured serum concentrations of GLN, GLU, and GABA and analyzed their correlations with AIS and HAMD scores. Results: Our results indicate no significant difference in the serum levels of GLN, GLU, and GABA between the post-stroke insomnia and depression groups. However, these levels were notably lower in both patient groups compared to the healthy control group. A negative correlation between AIS scores and GABA levels was observed in the post-stroke insomnia group, suggesting a potential link between GABAergic disturbances and insomnia. Conversely, no significant correlation was found between Hamilton Depression Rating Scale scores and the levels of GABA, GLU, or GLN in the post-stroke depression group. Conclusion: The study highlights that abnormalities in the GLU/GABA to GLN metabolic cycle, particularly the levels of GLN, GABA, and GAD, might be intricately linked to the pathogenesis of post-stroke insomnia and depression. Our findings suggest that GABAergic imbalances could be indicative of post-stroke insomnia, serving as potential biological markers for differential diagnosis in clinical settings. Further research is warranted to explore these relationships in greater depth, potentially leading to new diagnostic and therapeutic approaches for post-stroke neuropsychiatric disorders.

Functional Proteomics Analysis of Norfloxacin-Resistant Edwardsiella tarda.

Multidrug-resistant Edwardsiella tarda threatens both sustainable aquaculture and human health, but the control measure is still lacking. In this study, we adopted functional proteomics to investigate the molecular mechanism underlying norfloxacin (NOR) resistance in E. tarda. We found that E. tarda had a global proteomic shift upon acquisition of NOR resistance, featured with increased expression of siderophore biosynthesis and Fe3+-hydroxamate transport. Thus, either inhibition of siderophore biosynthesis with salicyl-AMS or treatment with another antibiotic, kitasamycin (Kit), which was uptake through Fe3+-hydroxamate transport, enhanced NOR killing of NOR-resistant E. tarda both in vivo and in vitro. Moreover, the combination of NOR, salicyl-AMS, and Kit had the highest efficacy in promoting the killing effects of NOR than any drug alone. Such synergistic effect not only confirmed in vitro and in vivo bacterial killing assays but also applicable to other clinic E. tarda isolates. Thus, our data suggest a proteomic-based approach to identify potential targets to enhance antibiotic killing and propose an alternative way to control infection of multidrug-resistant E. tarda.

Interspecies co-expression analysis of lateral root development using inducible systems in rice, Medicago, and Arabidopsis.

Lateral roots are crucial for plant growth and development, making them an important target for research aiming to improve crop yields and food security. However, their endogenous ontogeny and, as it were, stochastic appearance challenge their study. Lateral Root Inducible Systems (LRIS) can be used to overcome these challenges by inducing lateral roots massively and synchronously. The combination of LRISs with transcriptomic approaches significantly advanced our insights in the molecular control of lateral root formation, in particular for Arabidopsis. Despite this success, LRISs have been underutilized for other plant species or for lateral root developmental stages later than the initiation. In this study, we developed and/or adapted LRISs in rice, Medicago, and Arabidopsis to perform RNA-sequencing during time courses that cover different developmental stages of lateral root formation and primordium development. As such, our study provides three extensive datasets of gene expression profiles during lateral root development in three different plant species. The three LRISs are highly effective but timing and spatial distribution of lateral root induction vary among the species. Detailed characterization of the stages in time and space in the respective species enabled an interspecies co-expression analysis to identify conserved players involved in lateral root development, as illustrated for the AUX/IAA and LBD gene families. Overall, our results provide a valuable resource to identify potentially conserved regulatory mechanisms in lateral root development, and as such will contribute to a better understanding of the complex regulatory network underlying lateral root development.

Rice roots avoid asymmetric heavy metal and salinity stress via an RBOH-ROS-auxin signaling cascade.

Root developmental plasticity is crucial for plants to adapt to a changing soil environment, where nutrients and abiotic stress factors are distributed heterogeneously. How plant roots sense and avoid heterogeneous abiotic stress in soil remains unclear. Here, we show that, in response to asymmetric stress of heavy metals (cadmium, copper, or lead) and salt, rice roots rapidly proliferate lateral roots (LRs) in the stress-free area, thereby remodeling root architecture to avoid localized stress. Imaging and quantitative analyses of reactive oxygen species (ROS) showed that asymmetric stress induces a ROS burst in the tips of the exposed roots and simultaneously triggers rapid systemic ROS signaling to the unexposed roots. Addition of a ROS scavenger to either the stressed or stress-free area abolished systemic ROS signaling and LR proliferation induced by asymmetric stress. Asymmetric stress also enhanced cytosolic calcium (Ca2+) signaling; blocking Ca2+signaling inhibited systemic ROS propagation and LR branching in the stress-free area. We identified two plasma-membrane-localized respiratory burst oxidase homologs, OsRBOHA and OsRBOHI, as key players in systemic ROS signaling under asymmetric stress. Expression of OsRBOHA and OsRBOHI in roots was upregulated by Cd stress, and knockout of either gene reduced systemic ROS signaling and LR proliferation under asymmetric stress. Furthermore, we demonstrated that auxin signaling and cell wall remodeling act downstream of the systemic ROS signaling to promote LR development. Collectively, our study reveals an RBOH-ROS-auxin signaling cascade that enables rice roots to avoid localized stress of heavy metals and salt and provides new insight into root system plasticity in heterogenous soil.

GH3-mediated auxin inactivation attenuates multiple stages of lateral root development.

Lateral root (LR) positioning and development rely on the dynamic interplay between auxin production, transport but also inactivation. Nonetheless, how the latter affects LR organogenesis remains largely uninvestigated. Here, we systematically analyze the impact of the major auxin inactivation pathway defined by GRETCHEN HAGEN3-type (GH3) auxin conjugating enzymes and DIOXYGENASE FOR AUXIN OXIDATION1 (DAO1) in all stages of LR development using reporters, genetics and inhibitors in Arabidopsis thaliana. Our data demonstrate that the gh3.1/2/3/4/5/6 hextuple (gh3hex) mutants display a higher LR density due to increased LR initiation and faster LR developmental progression, acting epistatically over dao1-1. Grafting and local inhibitor applications reveal that root and shoot GH3 activities control LR formation. The faster LR development in gh3hex is associated with GH3 expression domains in and around developing LRs. The increase in LR initiation is associated with accelerated auxin response oscillations coinciding with increases in apical meristem size and LR cap cell death rates. Our research reveals how GH3-mediated auxin inactivation attenuates LR development. Local GH3 expression in LR primordia attenuates development and emergence, whereas GH3 effects on pre-initiation stages are indirect, by modulating meristem activities that in turn coordinate root growth with LR spacing.

Plastid-localized amino acid metabolism coordinates rice ammonium tolerance and nitrogen use efficiency.

Ammonium toxicity affecting plant metabolism and development is a worldwide problem impeding crop production. Remarkably, rice (Oryza sativa L.) favours ammonium as its major nitrogen source in paddy fields. We set up a forward-genetic screen to decipher the molecular mechanisms conferring rice ammonium tolerance and identified rohan showing root hypersensitivity to ammonium due to a missense mutation in an argininosuccinate lyase (ASL)-encoding gene. ASL localizes to plastids and its expression is induced by ammonium. ASL alleviates ammonium-inhibited root elongation by converting the excessive glutamine to arginine. Consequently, arginine leads to auxin accumulation in the root meristem, thereby stimulating root elongation under high ammonium. Furthermore, we identified natural variation in the ASL allele between japonica and indica subspecies explaining their different root sensitivity towards ammonium. Finally, we show that ASL expression positively correlates with root ammonium tolerance and that nitrogen use efficiency and yield can be improved through a gain-of-function approach.

RNA-seq analysis reveals an immunomodulatory peptide from highland barley activating RAW264.7 macrophages via TNF/NF-κB signaling pathway.

Highland barley (HB) is an important cereal crop distributed in the plateau region. Bioactive peptides (BAPs) derived from cereal proteins have shown biological functions. However, the knowledge of highland barley peptide (HBP) is limited. This study aims to explore the immunomodulatory activity of HBP and the relationship between immunomodulatory activity and related gene expression through RNA-seq. Firstly, HBP is isolated from protease hydrolysates of HB protein, yielding 12.04% of crude HB protein. The molecular weight of HBP is about 1702 Da analyzed by gel filtration chromatography, and HBP has a specific amino acid sequence as Gln-Pro-Gln-Gln-Pro-Phe-Pro-Gln (QPQPFPQ) analyzed by LC-MS. Besides, HBP contains 42.20% hydrophobic amino acids and 10.86% basic amino acids. Next, the immunomodulatory activity of HBP in vitro shows that HBP enhances the phagocytosis of RAW264.7 macrophages, promotes nitric oxide (NO) production and the mRNA expression of pro-inflammatory genes including tumor necrosis factor α (TNF-α), interleukin 1ß (IL-1ß), and inducible nitric oxide synthase (iNOS), and decreases the mRNA expression of anti-inflammatory gene, transforming growth factor ß1 (TGF-ß1). RNA-seq analysis reveals TNF and nuclear factor kappa B (NF-κB) pathways are upregulated, and RT-qPCR is performed to verify RNA-seq analysis. In conclusion, HBP activates RAW264.7 macrophages via TNF/NF-κB signaling pathway. HBP, as a significant immunomodulatory peptide, might be a promising resource for future functional foods.

Perimeter procedure to produce average equivalent area grain size.

A new method of perimeter procedure to produce average equivalent area grain size on orientation imaging microscopy (OIM) micrograph was developed. When the OIM micrograph was exported with the practical size of pixel equal to the electron backscattering diffraction (EBSD) step size, the expression for perimeter procedure in producing the average equivalent area radius is r¯p=(2AmPm+wb2Es)±wb2Es (Pm and Am are the perimeter and area of grains, respectively, which can be measured using commercial image pro plus software; wb is the pixel width of the grain boundary which is suggested to set as 1 and Es is the EBSD step size). Experiments were conducted and the four methods intercept procedure, planimetric procedure, perimeter procfedure and statistical method were adopted to measure the average grain sizes for different conditions (polygonal grains and compressed polygonal grains, different EBSD step sizes, different grain boundary widths). The results showed that the average grain size by perimeter procedure remained relatively unchanged and close to the true average grain size for all conditions. It was demonstrated that perimeter procedure has an advantage in that it can produce reliable average grain size even when the pixel step size relative to the grain size is relatively large.

Genome-wide association studies identify OsWRKY53 as a key regulator of salt tolerance in rice.

Salinity stress progressively reduces plant growth and productivity, while plant has developed complex signaling pathways to confront salt stress. However, only a few genetic variants have been identified to mediate salt tolerance in the major crop rice, and the molecular mechanism remains poorly understood. Here, we identify ten candidate genes associated with salt-tolerance (ST) traits by performing a genome-wide association analysis in rice landraces. We characterize two ST-related genes, encoding transcriptional factor OsWRKY53 and Mitogen-activated protein Kinase Kinase OsMKK10.2, that mediate root Na+ flux and Na+ homeostasis. We further find that OsWRKY53 acts as a negative modulator regulating expression of OsMKK10.2 in promoting ion homeostasis. Furthermore, OsWRKY53 trans-represses OsHKT1;5 (high-affinity K+ transporter 1;5), encoding a sodium transport protein in roots. We show that the OsWRKY53-OsMKK10.2 and OsWRKY53-OsHKT1;5 module coordinate defenses against ionic stress. The results shed light on the regulatory mechanisms underlying plant salt tolerance.