Melatonin confers tolerance to nitrogen deficiency through regulating MdHY5 in apple plants.

Nitrogen (N) is an essential nutrient for crop growth and development, significantly influencing both yield and quality. Melatonin (MT), a known enhancer of abiotic stress tolerance, has been extensively studied. However, its relationship with nutrient stress, particularly N deficiency, and the underlying regulatory mechanisms of MT on N absorption remain unclear. In this study, exogenous MT treatment was found to improve the tolerance of apple plants to N deficiency. Apple plants overexpressing the MT biosynthetic gene N-acetylserotonin methyltransferase 9 (MdASMT9) were used to further investigate the effects of endogenous MT on low-N stress. Overexpression of MdASMT9 improved the light harvesting and heat transfer capability of apple plants, thereby mitigating the detrimental effects of N deficiency on the photosynthetic system. Proteomic and physiological data analyses indicated that MdASMT9 overexpression enhanced the trichloroacetic acid cycle and positively modulated amino acid metabolism to counteract N-deficiency stress. Additionally, both exogenous and endogenous MT promoted the transcription of MdHY5, which in turn bound to the MdNRT2.1 and MdNRT2.4 promoters and activated their expression. Notably, MT-mediated promotion of MdNRT2.1 and MdNRT2.4 expression through regulating MdHY5, ultimately enhancing N absorption. Taken together, these findings shed light on the association between MdASMT9-mediated MT biosynthesis and N absorption in apple plants under N-deficiency conditions.

In Vivo Toxicology of Metabolizable Atomically Precise Au25 Clusters at Ultrahigh Doses.

Ultrasmall Au25(MPA)18 clusters show great potential in biocatalysts and bioimaging due to their well-defined, tunable structure and properties. Hence, in vivo pharmacokinetics and toxicity of Au nanoclusters (Au NCs) are very important for clinical translation, especially at high dosages. Herein, the in vivo hematological, tissue, and neurological effects following exposure to Au NCs (300 and 500 mg kg-1) were investigated, in which the concentration is 10 times higher than in therapeutic use. The biochemical and hematological parameters of the injected Au NCs were within normal limits, even at the ultrahigh level of 500 mg kg-1. Meanwhile, no histopathological changes were observed in the Au NC group, and immunofluorescence staining showed no obvious lesions in the major organs. Furthermore, real-time near-infrared-II (NIR-II) imaging showed that most of the Au25(MPA)18 and Au24Zn1(MPA)18 can be metabolized via the kidney. The results demonstrated that Au NCs exhibit good biosafety by evaluating the manifestation of toxic effects on major organs at ultrahigh doses, providing reliable data for their application in biomedicine.

MdASMT9-mediated melatonin biosynthesis enhances basal thermotolerance in apple plants.

High temperatures negatively impact the yield and quality of fruit crops. Exogenous melatonin (MT) application has been shown to enhance heat tolerance, but the response of endogenous MT to heat stress, particularly in perennial fruit trees, remains unclear. The present study investigated the effects of high temperatures on transgenic apple plants overexpressing the MT biosynthesis gene N-acetylserotonin methyltransferase 9 (MdASMT9). Endogenous MT protected transgenic plants from heat stress by increasing antioxidant enzyme activity and scavenging reactive oxygen species (ROS), and protecting the chloroplasts from damage. Application of MT and overexpression of MdASMT9 also reduced abscisic acid accumulation through promoting MdWRKY33-mediated transcriptional inhibition of MdNCED1 and MdNCED3, thus inducing stomatal opening for better heat dissipation. Furthermore, MT-enhanced autophagic activity through promoting MdWRKY33-mediated transcriptional enhancement of MdATG18a under heat stress. These findings provide new insights into the regulation of endogenous MT and its role in improving basal thermotolerance in perennial fruit trees.

Interface Engineering of PtZn Alloy and Nb2O5 for Promoting Ammonia Oxidation Reaction and Hydrogen Evolution Reaction.

Ammonia electrolysis is a promising technology to obtain green hydrogen with zero-carbon emission, in which ammonia oxidation reaction (AOR) and hydrogen evolution reaction (HER) occur at the anode and cathode, respectively. However, the lack of efficient catalysts hinders its practical application. Herein, PtZn alloy is combined with Nb2O5 to construct a bifunctional heterostructure catalyst (PtZn-Nb2O5/C). The optimal sample with Nb2O5 content of 7.05 wt % demonstrates the best performance with a peak current density of 304.1 mA mg-1Pt for AOR, and it is only reduced by 17.0% after 4000 cycles of durability tests. For HER, it has a low overpotential of 34 mV at -10 mA cm-2 under the alkaline condition. This can be ascribed to the interfacial interaction between the PtZn alloy and Nb2O5, which adjusts the adsorption behavior of OHad to concurrently promote AOR and HER activity. This work thus proposes a viable strategy to design an efficient bifunctional catalyst for hydrogen generation from ammonia electrolysis.

Two Mn(II)-Bridged Silverton-Type [UMo12O42]8- Polyoxometalates with Catalytic Activity for the Synthesis of Pyrazoles.

Two Mn(II)-bridged Silverton-type {UMo12O42}-based polyoxomolybdates with different three-dimensional structures, Na6(H2O)12[Mn(UMo12O42)] (NaMn) and (NH4)2[K2Na6(µ4-O)2(H2O)1.2Mn(UMo12O42)]·4.6H2O (KMn), were hydrothermally synthesized and further characterized, demonstrating a feasible strategy for the assembly of Silverton-type polyoxomolybdates. Additionally, NaMn is demonstrated to be a good heterogeneous catalyst in the condensation cyclization reaction of hydrazines and 1,3-diketones, and a range of valuable pyrazoles were produced in up to 99% yield.

Application of gold nanoclusters in fluorescence sensing and biological detection.

Gold nanoclusters (Au NCs) exhibit broad fluorescent spectra from visible to near-infrared regions and good enzyme-mimicking catalytic activities. Combined with excellent stability and exceptional biocompatibility, the Au NCs have been widely exploited in biomedicine such as biocatalysis and bioimaging. Especially, the long fluorescence lifetime and large Stokes shift attribute Au NCs to good probes for fluorescence sensing and biological detection. In this review, we systematically summarized the molecular structure and fluorescence properties of Au NCs and highlighted the advances in fluorescence sensing and biological detection. The Au NCs display high sensitivity and specificity in detecting iodine ions, metal ions, and reactive oxygen species, as well as certain diseases based on the fluorescence activities of Au NCs. We also proposed several points to improve the practicability and accelerate the clinical translation of the Au NCs.

Single Atom-Engineered NIR-II Gold Clusters with Ultrahigh Brightness and Stability for Acute Kidney Injury.

Near-infrared-II (NIR-II) imaging has shown great potential for monitoring the pathological progression and deep tissue imaging but is limited to present unmet NIR-II agent. Present fluorophores show a promising prospect for NIR-II imaging, but brightness and photostability are still highly challenging during real-time monitoring. In this work, atom-engineered NIR-II Au24 Cd1  clusters with ultrahigh brightness, stability, and photostability are developed via single atomic Cd doping. Single atom Cd substitutions contribute to Cd 4d state in HOMO and redistribution of energy level near the gap, exhibiting 56-fold fluorescence enhancement of Au24 Cd1  clusters. Meanwhile, single atomic Cd reinforces CdAu bond energy, formation energy, and stabilized cluster structure, leading to persistent stability for up to 1 month without decay, as well as excellent photostability of 1 h without photobleaching, much longer than clinically approved indocyanine green (<5 min). In vivo imaging shows gold clusters can monitor acute kidney injury (AKI) even after 72 h of injury, enabling evaluating progression at a very long window. Meanwhile, the bioactive gold clusters can alleviate AKI-induced oxidative stress damage and acute neuroinflammation. Single atom-engineered gold clusters exhibit molecular tracking and diagnostic prospect in kidney-related diseases.

Two-Fold Interpenetrated Binuclear Nickel Metal-Organic Framework as a Heterogeneous Catalyst for N-Heterocycle Synthesis.

A binuclear Ni(II)-based metal-organic framework {[Ni2(btb)1.333(H2O)3.578(py)1.422]·(DMF)(H2O)3.25}n (Nibtb) was solvothermally synthesized (H3btb = 1,3,5-tri(4-carboxylphenyl)benzene, py = pyridine, DMF = N,N-dimethylformamide). Nibtb shows a rare 2-fold interpenetrating (3,4)-connected 3D network with a point symbol of (83)4(86)3 based on binuclear Ni(II) clusters. Nibtb as a heterogeneous catalyst combines the high stability of MOFs and excellent catalytic activity of nickel, which exhibits excellent catalytic activity for the synthesis of benzimidazoles and pyrazoles under mild conditions. Moreover, the catalyst can be easily separated and reused for seven successive cycles and maintains high catalytic activity.

Tuning d-Band Center of Pt by PtCo-PtSn Heterostructure for Enhanced Oxygen Reduction Reaction Performance.

The development of efficient and stable Pt-based catalysts is significant but challenging for fuel cells. Herein, Sn and Co elements are introduced into Pt to form PtCo-PtSn/C heterostructure for enhancing the oxygen reduction reaction (ORR). Electrochemical results indicate that it has remarkable ORR intrinsic activity with a high mass activity (1,158 mA mg-1 Pt) at 0.9 V in HClO4 solution, which is 2.18-, 6.81-, and 9.98-fold higher than that of PtCo/C, PtSn/C, and Pt/C. More importantly, the catalytic activity attenuation for PtCo-PtSn/C is only 27.4% after 30 000 potential cycles, showing high stability. Furthermore, theoretical calculations reveal that the enhancement is attributed to charge transfer and the unique structure of PtCo-PtSn/C heterostructure, which regulate the d-band center of Pt and prevent non-noble metals from further dissolution. This work thus opens a way to design and prepare highly efficient Pt-based alloy catalysts for proton exchange membrane fuel cells.

Heterologous Expression of the Melatonin-Related Gene HIOMT Improves Salt Tolerance in Malus domestica.

Melatonin, a widely known indoleamine molecule that mediates various animal and plant physiological processes, is formed from N-acetyl serotonin via N-acetylserotonin methyltransferase (ASMT). ASMT is an enzyme that catalyzes melatonin synthesis in plants in the rate-determining step and is homologous to hydroxyindole-O-methyltransferase (HIOMT) melatonin synthase in animals. To date, little is known about the effect of HIOMT on salinity in apple plants. Here, we explored the melatonin physiological function in the salinity condition response by heterologous expressing the homologous human HIOMT gene in apple plants. We discovered that the expression of melatonin-related gene (MdASMT) in apple plants was induced by salinity. Most notably, compared with the wild type, three transgenic lines indicated higher melatonin levels, and the heterologous expression of HIOMT enhanced the expression of melatonin synthesis genes. The transgenic lines showed reduced salt damage symptoms, lower relative electrolyte leakage, and less total chlorophyll loss from leaves under salt stress. Meanwhile, through enhanced activity of antioxidant enzymes, transgenic lines decreased the reactive oxygen species accumulation, downregulated the expression of the abscisic acid synthesis gene (MdNCED3), accordingly reducing the accumulation of abscisic acid under salt stress. Both mechanisms regulated morphological changes in the stomata synergistically, thereby mitigating damage to the plants' photosynthetic ability. In addition, transgenic plants also effectively stabilized their ion balance, raised the expression of salt stress-related genes, as well as alleviated osmotic stress through changes in amino acid metabolism. In summary, heterologous expression of HIOMT improved the adaptation of apple leaves to salt stress, primarily by increasing melatonin concentration, maintaining a high photosynthetic capacity, reducing reactive oxygen species accumulation, and maintaining normal ion homeostasis.

Dy/Ho-encapsulated tartaric acid-functionalized tungstoantimonates: heterogeneous catalysts for isoindolinone synthesis.

Two novel rare earth-substituted tungstoantimonates [H2N(CH3)2]8Na12[Dy2(H2O)6(tar)(Sb2W21O72)]2·40H2O (DySbW) and [H2N(CH3)2]6Na14[Ho2(H2O)6(tar)(Sb2W21O72)]2·25H2O (HoSbW) (H4tar = tartaric acid) were synthesized. The meso-polyanions are alternately linked by {Na3(H2O)3} clusters and DL-tar ligands to form 1D chains. Notably, HoSbW exhibits excellent catalytic activity and high stability for the synthesis of isoindolinones using EtOH as a green solvent.

Research progress of optic nerve imaging during 1991-2023: a bibliometric analysis.

Background: Optic nerve imaging is crucial for diagnosing and understanding optic neuropathies because it provides detailed visualization of the nerve's structure and pathologies through advanced modalities. This study conducted a bibliometric analysis within the field of optic nerve imaging, aiming to pinpoint the latest research trends and focal points in optic nerve imaging. Methods: The core literature on optic nerve imaging published between January 1991 and August 2023 was retrieved from the Web of Science Core Collection. The analysis and visualization of scientific productivity and emerging trends were facilitated through the utilization of Bibliometrix software, CiteSpace, Gephi, VOSviewer, R software, and Python. Results: In total, 15,247 publications on optic nerve imaging were included in the analysis. Notably, the top 3 journals contributing to this field were Investigative Ophthalmology & Visual Science, Ophthalmology, and the British Journal of Ophthalmology. This research on optic nerve imaging extended across 97 countries, with the USA leading in research endeavors. Noteworthy burst term analysis revealed that "Segmentation" and "Machine learning" are gaining attention. Additionally, the Latent Dirichlet Allocation model indicated that image processing has been a hotspot in recent years. Conclusions: This study revealed the research trends, hotspots, and emerging topics in optic nerve imaging through bibliometric analysis and network visualization. At present, the research focus is directed towards employing artificial intelligence for image post-processing. The findings of this study offer valuable insights into future research direction and clinical applications.

CT-based artificial intelligence prediction model for ocular motility score of thyroid eye disease.

PURPOSE: Thyroid eye disease (TED) is the most common orbital disease in adults. Ocular motility restriction is the primary complaint of patients, while its evaluation is quite difficult. The present study aimed to introduce an artificial intelligence (AI) model based on orbital computed tomography (CT) images for ocular motility score. METHODS: A total of 410 sets of CT images and clinical data were obtained from the hospital. To build a triple classification predictive model for ocular motility score, multiple deep learning models were employed to extract features of images and clinical data. Subgroup analyses based on pertinent clinical features were performed to test the efficacy of models. RESULTS: The ResNet-34 network outperformed Alex-Net and VGG16-Net in prediction of ocular motility score, with the optimal accuracy (ACC) of 0.907, 0.870, and 0.890, respectively. Subgroup analyses indicated no significant difference in ACC between active or inactive phase, functional visual field diplopia or peripheral visual field diplopia (p > 0.05). However, in the gender subgroup, the prediction model performed more accurately in female patients than males (p = 0.02). CONCLUSION: In conclusion, the AI model based on CT images and clinical data successfully realized automatic scoring of ocular motility in TED patients. This approach potentially enhanced the efficiency and accuracy of ocular motility evaluation, thus facilitating clinical application.

Safety and efficacy of restarting immune checkpoint inhibitors in non-small cell lung cancer patients following immune-related adverse events: a systematic review and meta-analysis.

OBJECTIVE: This meta-analysis aims to evaluate the safety and efficacy of restarting immune checkpoint inhibitors (ICIs) in patients with non-small cell lung cancer (NSCLC) after experiencing immune-related adverse events (irAEs). METHODS: A comprehensive search of PubMed, Web of Science, Embase, and the Cochrane Library was conducted to identify studies investigating the safety and efficacy of restarting ICIs in NSCLC patients after irAEs. Outcome measures, including objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) after ICI restarting, were extracted. Meta-analysis was performed using the R meta-package. RESULTS: Four studies involving a total of 326 subjects were included, comprising 137 patients who restarted ICI treatment after irAEs and 189 patients who did not restart ICI treatment. The results revealed that ICI restarting was associated with an increased ORR (OR = 2.36, 95% CI 1.49-3.84), prolonged PFS (HR = 0.60, 95% CI 0.42-0.86), and prolonged OS (HR = 0.65, 95% CI 0.43-0.99) compared to non-restarting. The incidence of irAEs after ICI restarting was 45% (95% CI 0.27-0.63). CONCLUSION: Restarting ICI treatment after discontinuation due to previous irAEs appears to be a reasonable option for NSCLC patients. However, a comprehensive assessment of the potential benefits and risks to individual patients is crucial, and close monitoring of irAEs is warranted.

Microsatellite instability-related prognostic risk score (MSI-pRS) defines a subset of lung squamous cell carcinoma (LUSC) patients with genomic instability and poor clinical outcome.

Background: Lung squamous cell carcinoma (LUSC) shares less typical onco-drivers and target resistance, but a high overall mutation rate and marked genomic complexity. Mismatch repair (MMR) deficiency leads to microsatellite instability (MSI) and genomic instability. MSI is not an ideal option for prognosis of LUSC, whereas its function deserves exploration. Method: MSI status was classified by MMR proteins using unsupervised clustering in the TCGA-LUSC dataset. The MSI score of each sample was determined by gene set variation analysis. Intersections of the differential expression genes and differential methylation probes were classified into functional modules by weighted gene co-expression network analysis. Least absolute shrinkage and selection operator regression and stepwise gene selection were performed for model downscaling. Results: Compared with the MSI-low (MSI-L) phenotype, MSI-high (MSI-H) displayed higher genomic instability. The MSI score was decreased from MSI-H to normal samples (MSI-H > MSI-L > normal). A total of 843 genes activated by hypomethylation and 430 genes silenced by hypermethylation in MSI-H tumors were classified into six functional modules. CCDC68, LYSMD1, RPS7, and CDK20 were used to construct MSI-related prognostic risk score (MSI-pRS). Low MSI-pRS was a protective prognostic factor in all cohorts (HR = 0.46, 0.47, 0.37; p-value = 7.57e-06, 0.009, 0.021). The model contains tumor stage, age, and MSI-pRS that showed good discrimination and calibration. Decision curve analyses indicated that microsatellite instability-related prognostic risk score added extra value to the prognosis. A low MSI-pRS was negatively correlated with genomic instability. LUSC with low MSI-pRS was associated with increased genomic instability and cold immunophenotype. Conclusion: MSI-pRS is a promising prognostic biomarker in LUSC as the substitute of MSI. Moreover, we first declared that LYSMD1 contributed to genomic instability of LUSC. Our findings provided new insights in the biomarker finder of LUSC.

Treatment patterns and clinical outcomes in 157 patients with extensive-stage small cell lung cancer: real-world evidence from a single-center retrospective study.

Background: Immune checkpoint inhibitors (ICIs) have changed the therapeutic options for extensive-stage small-cell lung cancer (ES-SCLC). In this real-world study, we analyzed the treatment patterns in patients with ES-SCLC and evaluated the efficacy of chemotherapy combined with immunotherapy as first-line therapy. Methods: A retrospective analysis was performed on patients with ES-SCLC who received treatment at China-Japan Friendship Hospital (Beijing, China) between August 1, 2020, and April 30, 2023. The treatment patterns appeared in the form of Sunburst Chart and Sankey diagram. The survival analyses were conducted by Kaplan-Meier curves. Results: A total of 157 patients with ES-SCLC were retrospectively included. According to first-line therapy, patients were divided into the chemotherapy (CT) group (n=82) and chemo-immunotherapy (CIT) group (n=75). The median treatment lines were 2[1, 2] and cycles were 8[5, 12], respectively. 82 patients received the second line of therapy, followed by 37 for the third, 15 for the fourth, 11 for the fifth, and 5 for the sixth. Overall, the treatment patterns involved 11 options including 12 chemotherapy regimens, 11 ICIs, and 4 targeted agents. The second-line treatment pattern had the most options (9) and regimens (43). In the first 3 lines, chemotherapy was the largest proportion of treatment options. The addition of ICIs prolonged progression-free survival from 6.77 (95% confidence interval [CI], 6.00-7.87) to 7.33 (95% CI, 6.03-9.80) months (hazard ratio [HR]=0.67, 95% CI, 0.47-0.95; P=0.025), overall survival from 12.97 (10.90-23.3) to 14.33 (12.67-NA) months without statistically significant difference (HR=0.86, 95% CI, 0.55-1.34; P=0.505). Conclusion: The treatment options of patients with ES-SCLC are more diversified. Combination therapy is the current trend, where chemotherapy is the cornerstone. Meanwhile, ICIs participate in almost all lines of treatment. However, the clinical efficacy remains barely satisfactory. We are urgently expecting more breakthrough therapies except immunology will be applied in the clinic.

Efficacy and Safety of Immune Checkpoint Inhibitors in Patients with Cancer and Hepatitis B or C: A Systematic Review and Meta-Analysis.

Background: Immune checkpoint inhibitors (ICIs) have changed the situation of tumor therapy in recent years. However, for security reasons, those special populations are often excluded from clinical trials, such as infected hepatitis B or hepatitis C patients. ICIs are systematically reviewed and meta-analyzed for the first time in patients infected with hepatitis B or C in this paper. Methods: The relevant studies were searched in PubMed, EMBASE, Cochrane Library, and Web of Science until October 2022. Trials and observational studies meeting the inclusion criteria were included. The outcomes included the effectiveness of ICIs in patients with HBC/HCV (ORR, DCR, mOS, and mPFS), the incidence of adverse reactions, high-grade adverse reactions, and abnormal liver enzymes. At the same time, these indexes were compared with those of uninfected patients. Results: A total of 2,625 patients were enrolled, involving 1,179 patients with hepatitis (HBV or HCV). We found that ICIs showed higher ORR (25.80% vs. 18.10%) and DCR (66.22% vs. 58.74%) in patients with hepatitis B/C than those without infection. In terms of survival time, patients with hepatitis virus infection showed longer mOS (15.44 m vs. 13.30 m) but shorter mPFS (4.94 m vs. 5.01 m) than uninfected patients. As for safety data, patients with hepatitis showed a lower incidence of all-grade irAEs (68.02% vs. 70.43%) than uninfected patients, while that of 3-4 irAEs (21.27% vs. 21.79%) was similar in the two groups. However, hepatic dysfunction was more common and serious in hepatitis patients. Four HBVr and no HCVr were observed. Conclusion: According to this meta-analysis, ICIs are effective and safe for patients with hepatitis B or C, but basic liver enzymes have to be evaluated before treatment to avoid liver adverse events.

Bioactive NIR-II gold clusters for three-dimensional imaging and acute inflammation inhibition.

Strong fluorescence and high catalytic activities cannot be achieved simultaneously due to conflicts in free electron utilization, resulting in a lack of bioactivity of most near-infrared-II (NIR-II) fluorophores. To circumvent this challenge, we developed atomically precise Au22 clusters with strong NIR-II fluorescence ranging from 950 to 1300 nm exhibiting potent enzyme-mimetic activities through atomic engineering to create active Cu single-atom sites. The developed Au21Cu1 clusters show 18-fold higher antioxidant, 90-fold higher catalase-like, and 3-fold higher superoxide dismutase-like activities than Au22 clusters, with negligible fluorescence loss. Doping with single Cu atoms decreases the bandgap from 1.33 to 1.28 eV by predominant contributions from Cu d states, and Cu with lost electron states effectuates high catalytic activities. The renal clearable clusters can monitor cisplatin-induced renal injury in the 20- to 120-minute window and visualize it in three dimensions using NIR-II light-sheet microscopy. Furthermore, the clusters inhibit oxidative stress and inflammation in the cisplatin-treated mouse model, particularly in the kidneys and brain.

Changes of IL-6 And IFN-γ before and after the adverse events related to immune checkpoint inhibitors: A retrospective study.

Immune checkpoint inhibitors (ICIs) have changed the status of tumor immunotherapy. ICIs-related adverse events (irAEs) have the high incidence and are difficult to predict and prevent. Researches have suggested that changes of cytokines were associated with irAEs. This study focused on the changes of interleukin-6 (IL-6) and interferon-γ in patients before and after irAEs and trying to find the biomarkers of irAEs. Collect basic data of patients who were treated with ICIs in China-Japan Friendship Hospital from January 2017 to August 2021 and had irAEs. Make statistics on IL-6 and INF-γ in the blood before and after irAEs. A total of 10 patients were enrolled, including 7 males and 3 females. According to statistical analysis, the IL-6 concentration level after irAEs was significantly higher than before, and the difference was statistically significant (P = .023); the interferon-γ concentration level was not changed significantly from before, the difference was not statistically significant (P = .853). The elevation of IL-6 was associated with the occurrence of adverse reactions in ICIs.

Introducing melatonin to the horticultural industry: physiological roles, potential applications, and challenges.

Melatonin (N-acetyl-5-methoxytryptamine) is an emerging biomolecule that influences horticultural crop growth, flowering, fruit ripening, postharvest preservation, and stress protection. It functions as a plant growth regulator, preservative and antimicrobial agent to promote seed germination, regulate root system architecture, influence flowering and pollen germination, promote fruit production, ensure postharvest preservation, and increase resistance to abiotic and biotic stresses. Here, we highlight the potential applications of melatonin in multiple aspects of horticulture, including molecular breeding, vegetative reproduction, production of virus-free plants, food safety, and horticultural crop processing. We also discuss its effects on parthenocarpy, autophagy, and arbuscular mycorrhizal symbiosis. Together, these many features contribute to the promise of melatonin for improving horticultural crop production and food safety. Effective translation of melatonin to the horticultural industry requires an understanding of the challenges associated with its uses, including the development of economically viable sources.