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Evidence exists to suggest that melatonin (MT) is important to abiotic stress tolerance in plants. Here, we investigated whether exogenous MT reduces heat damage on biological parameters and gene expression in kiwifruit (Actinidia deliciosa) seedlings. Pretreatment with MT alleviates heat-induced oxidative harm through reducing H2O2 content and increasing proline content. Moreover, MT application raised ascorbic acid (AsA) levels and the activity of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). We also observed elevation in the activity of enzymes related to the AsA-GSH cycle, such as ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR). Furthermore, MT application increased the expression of 28/31 glutathione S-transferase (GST) genes, reducing oxidative stress. These results clearly indicate that in kiwifruit, MT exerts a protective effect against heat-related damage through regulating antioxidant pathways.

Melatonin, a multiple signal molecule, plays important roles in delaying senescence during the development of plants. Because few species have been studied for the effect of exogenous melatonin on anti-aging, the plausible mechanism of melatonin of anti-aging effects on other plant species has remained largely unknown. In the present study, the effects of exogenous melatonin on leaf senescence in kiwifruit were examined during natural aging after melatonin (200 μM) or water (Control) pretreatment. The decreased membrane damage and lower hydrogen peroxide (H O ) content due to the enhanced scavenging activity of antioxidant enzymes peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) demonstrated that melatonin effectively delayed the aging of kiwifruit leaves. Likewise, owing to up-regulated expression of chlorophyll a/b-binding protein ( ) gene in the sampled leaves pretreated with melatonin, chlorophyll degradation decreased. Therefore, osmoregulatory substances in sampled leaves accumulated (e.g., soluble sugar and soluble protein) and seedling cell environment stability was maintained. Simultaneously, melatonin decreased H O concentration owing to increased glutathione (GSH) and ascorbate (AsA) content, and the expression levels of glutathione reductase ( ), ascorbate peroxidase ( ), monodehydroascorbate reductase ( ), dehydroascorbate reductase ( ) were up-regulated by melatonin application, indicating that the increase of GSH and AsA was attributed to the expression of these genes. In addition, a large amount of flavonoids accumulated in seedlings pretreated with melatonin, and transcript levels of eight genes involved in flavonoid synthesis, including phenylalanine ammonia-lyase ( ), cinnamate-4-hydroxymate ( ), chalcone synthase ( ), flavanone 3-hydroxylase ( ), flavonol synthase ( ), leucoanthocyanin reductase ( ), anthocyanin reductase ( ), flavonoid 3- -glucosyltransferase ( ) were enhanced in response to melatonin application. These results indicated that melatonin delayed aging of kiwifruit leaves by activating the antioxidant capacity and enhancing flavonoid biosynthesis. All of these results can provide clear proof that melatonin plays a key roles in delaying leaf senescence.

Although the effects of melatonin on plant abiotic and biotic stress resistance have been explored in recent decades, the accumulation of endogenous melatonin in plants and its influence on fruit quality remains unclear. In the present study, melatonin accumulation levels and the expression profiles of five synthesis genes were investigated during fruit and leaf development in sweet cherry (Prunus avium L.). Melatonin was strongly accumulated in young fruits and leaves, then decreased steadily with maturation. Transcript levels of PacTDC and PacSNAT were highly correlated with melatonin content in both fruit and leaves, indicating their importance in melatonin accumulation. Furthermore, application of 50 and 100 μmol·L−1 of melatonin to leaves had a greater influence on fruit quality than treatments applied to fruits, by significantly improving fruit weight, soluble solids content, and phenolic content including total phenols, flavanols, total anthocyanins, and ascorbic acid. Meanwhile, melatonin application promoted the antioxidant capacity of fruit assayed by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azinobis (3-ethylben zothiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP). These results provide insights into the physiological and molecular mechanisms underlying melatonin metabolism of sweet cherry.

Background The American Heart Association recently introduced a novel cardiovascular health (CVH) metric, Life's Essential 8 (LE8), for health promotion. However, the relationship between LE8 and cancer mortality risk remains uncertain. Methods We investigated 17,076 participants from US National Health and Nutrition Examination Survey (US NHANES) and 272,727 participants from UK Biobank, all free of cancer at baseline. The CVH score, based on LE8 metrics, incorporates four health behaviors (diet, physical activity, smoking, and sleep) and four health factors (body mass index, lipid, blood glucose, and blood pressure). Self-reported questionnaires assessed health behaviors. Primary outcomes were mortality rates for total cancer and its subtypes. The association between CVH score (continuous and categorical variable) and outcomes was examined using Cox model with adjustments. Cancer subtypes-related polygenic risk score (PRS) was constructed to evaluate its interactions with CVH on cancer death risk. Results Over 141,526 person-years in US NHANES, 424 cancer-related deaths occurred, and in UK Biobank, 8,872 cancer deaths were documented during 3,690,893 person-years. High CVH was associated with reduced overall cancer mortality compared to low CVH (HR 0.58, 95% CI 0.37–0.91 in US NHANES; 0.51, 0.46–0.57 in UK Biobank). Each one-standard deviation increase in CVH score was linked to a 19% decrease in cancer mortality (HR: 0.81; 95% CI: 0.73–0.91) in US NHANES and a 19% decrease (HR: 0.81; 95% CI: 0.79–0.83) in UK Biobank. Adhering to ideal CVH was linearly associated with decreased risks of death from lung, bladder, liver, kidney, esophageal, breast, colorectal, pancreatic, and gastric cancers in UK Biobank. Furthermore, integrating genetic data revealed individuals with low PRS and high CVH exhibited the lowest mortality from eight cancers (HRs ranged from 0.36 to 0.57) compared to those with high PRS and low CVH. No significant modification of the association between CVH and mortality risk for eight cancers by genetic predisposition was observed. Subgroup analyses showed a more pronounced protective association for overall cancer mortality among younger participants and those with lower socio-economic status. Conclusions Maintaining optimal CVH is associated with a substantial reduction in the risk of overall cancer mortality. Adherence to ideal CVH correlates linearly with decreased mortality risk across multiple cancer subtypes. Individuals with both ideal CVH and high genetic predisposition demonstrated significant health benefits. These findings support adopting ideal CVH as an intervention strategy to mitigate cancer mortality risk and promote healthy aging.

To evaluated the effects melatonin (MT) on the sugar and acid metabolism of early-ripening peach fruits, the concentration of 150 μmol/L MT was sprayed on the leaves of peach trees. MT increased the contents of total soluble sugar and sucrose in peach fruits during the whole ripening period, and increased the contents of glucose and sorbitol at the mature stage. During the whole ripening period, MT also increased the activities of sucrose synthase, sucrose phosphate synthase, neutral invertase, and acidic invertase and the relative expression levels of sucrose synthase , sucrose phosphate synthase , neutral invertase , and acidic invertase genes, while decreased the activity of sorbitol oxidase and the relative expression level of sorbitol dehydrogenase to some extent. Moreover, MT decreased the contents of total organic acid, malic acid, and citric acid at mature stage. At mature stage, MT decreased the activities of citrate synthetase and phosphoenolpyruvate carboxylase and the relative expression levels of citrate synthetase and phosphoenolpyruvate carboxylase genes, while increased the relative expression levels of Nicotinamide adenine dinucleotide phosphate ( NADP + ) -malic enzyme , malate dehydrogenase , and aconitase genes. Therefore, MT promotes the sugar accumulation and organic acid degradation in early-ripening peach fruits.

Anthocyanins are important components in skins of red table grapes and contribute to the berries appearance, a key quality characteristic for customers. In recent years, exogenous foliage fertilizers has been applied to grapevines to improve the pigmentation of the fruit. The present study examines the effect on a biostimulant (SUNRED) pre- véraison application in the accumulation of anthocyanins in ‘Red Globe’ grapes, and investigates the related changes in expression of key genes and their enzyme activities in the flavonoid pathways. Additionally, abscisic acid (S-ABA) was also applied to grapevines to evaluate the comparative effect of SUNRED. Our analyses showed that total anthocyanin contents increased in both SUNRED and S-ABA treated grapes; for S-ABA, a 1% dilution (A100) of the commercially available stock solution treatments represented the greatest effect on pigmentation; for SUNRED, a 0.1% dilution (S1000) was most effective. The anthocyanin contents increased by 1.16-fold and 1.4-fold after A100 and S1000 treatments, respectively. The gene expression analyses showed that almost all genes involved in the anthocyanin biosynthesis pathway up-regulated after A100 and S1000 treatments, suggesting that the increment in total anthocyanin content was attributed to the increased expression level of related genes. Moreover, the activities of phenylalanine ammonia-lyase (PAL), chalcone isomerase (CHI), UDP glucose: flavonoid 3-o-glucosyl transferase (UFGT) and dihydroflavonol 4-reductase (DFR), key enzymes for biosynthesis of anthocyanin, were increased by the exogenous treatments. Overall, our findings clearly demonstrate that application of exogenous biostimulant have a positive effect on the pigment characteristics of grape crop.

Background Grape buds exhibit non-uniform, or delayed, break in early spring in subtropical regions because the accumulation of chilling is insufficient. Hydrogen cyanamide (H 2 CN 2 , HC) can partially replace chilling to effectively promote bud sprouting and is used widely in warm winter areas. However, the exact underlying mechanism of grape bud release from endodormancy induced by HC remains elusive. Results In this study, the transcriptome of grape winter buds under in vitro conditions following HC and water treatment (control) was analyzed using RNA-seq technology. A total of 6772 differentially expressed genes (DEGs) were identified. Furthermore, the gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that starch and sucrose metabolism and plant hormone signaling transduction were most enriched out of the 50 total pathways. HC treatment induced the upregulated expression of sucrose synthase (SUS), sucrose phosphate synthase (SPS), α-amylase (AM), and β-amylase (BM) and downregulated expression of sucrose invertase (INV), hexokinase (HK), fructokinase (FK), soluble starch synthase (SS), and granule-bound starch synthase (GBSS). Hence, the starch concentration in the HC-treated group was significantly lower than that in control, whereas soluble sugar content in the HC-treated group increased quickly and was higher than that in control between 0 and 8 d. The concentration of indoleacetic acid (IAA) and zeatin (ZT) increased, whereas that of abscisic acid (ABA) and gibberellin (GA) decreased in HC treated group, which coincided with the expression level of genes involved in above hormone signals. The content of hydrogen peroxide (H 2 O 2 ) and enzyme activity of superoxide dismutase (SOD) and peroxidase (POD) were increased in grape buds with HC treatment, whereas catalase (CAT) activity was decreased. HC treatment increased the expression of POD , SOD , primary amine oxidase ( PAO ), polyamine oxidase ( PAOX ), and glutathione peroxidase ( GSH-Px ). Conclusion Based on these results, it is possible to propose a mechanistic model that underlies the regulation of endodormancy release in grapevine buds by exogenous HC application.

Background Complete edentulism affects the quality of life and overall health. Identifying environmental factors linked to teeth lost may help address the global public health burden of oral health. This study aimed to estimate the association between neighborhood-level cumulative environmental burden and the prevalence of complete edentulism among the elderly across the US. Methods This cross-sectional study of 72 333 US neighborhoods using US Census tract-level data on environmental burden index (EBI) from the US CDC. Mixed-effects linear regression was applied to assess the relationship between neighborhood EBI and the prevalence of edentulism among the elderly, overall and by levels of neighborhood characteristics. The associations between 5 environmental burden domains and complete edentulism prevalence were further investigated. In addition, age proportion score-based matching and geospatially-based matching analyses were conducted to verify the robustness of the findings. Results Across the US, compared to neighborhoods with the low-EBI, neighborhoods with the high-EBI were more likely to be located in the urban, to be more social vulnerable, have a lower percentage of males and the elderly ( P  < 0.001). After fully adjustment, the beta[95%CI] of the EBI was 1.759[1.620, 1.899] ( P  < 0.001). Among all 5 environmental burden domains, the built environment showed the strongest association (β = 2.735, 95% CI: 2.581–2.891). These associations were more pronounced in neighborhoods with male-percentage < = 50% and higher SVI scores, as well as in the urban and the south neighborhoods in ( P  < 0.001). Results were consistent after age proportion score-based matching and geospatially-based matching analyses among the high-EBI and low-EBI neighborhoods. Conclusion This national study across US neighborhoods indicated a modest but statistically significant association between the cumulative environmental burden and the prevalence of complete edentulism among the elderly. Interventions targeting adverse environmental conditions may hold potential for promoting oral health in aging populations.

Melatonin (MT) can improve plant resistance and fruit quality. The mechanism by which MT affects soluble sugar and organic acids accumulation in drupe fruits is not clear. In this study, 100 µmol/L MT was sprayed on the leaves of plum trees at the second stage of rapid fruit expansion (90 and 97 d after flowering), and the effects of MT on plum fruit quality and its effects on the soluble sugar-organic acid metabolism were investigated. At 28 d after MT treatment (at maturity), the longitudinal diameter, fruit weight, and vitamin C content of plum fruits were increased by 5.05%, 12.93%, and 56.09%, respectively, compared to the control. MT caused significant increase in the total soluble solids content and decreased the titratable acid content. MT increased the contents of total soluble sugar, sucrose, sorbitol, and citric acid after 21 and 28 days of treatment, while decreasing the contents of fructose, malic acid, quinic acid, and tartaric acid after 28 days of treatment. Additionally, MT increased the activities of sucrose synthase (catabolism direction), sucrose phosphate synthase, glucokinase, fructokinase, sorbitol oxidase, and NADP + -malic enzyme, and decreased the activities of soluble acid converting enzyme, cell wall insoluble converting enzyme, NAD + -sorbitol dehydrogenase, and NAD + -malic dehydrogenase after 21 or 28 days of treatment. Moreover, the differentially expressed genes (DEGs) after 21 and 28 days of treatment were accelerated starch and sucrose metabolism, galactose metabolism, fructose and mannose metabolism, as well as glycolysis, gluconeogenesis, and pentose phosphate metabolism pathways. In conclusion, exogenous MT increases soluble sugar content and decreases organic acid content in plum fruits by regulating various soluble sugar-organic acid metabolic pathways, thereby improving the fruit quality.

Low temperature (LT) restricts the growth and development of pitaya, therefore mitigating these detrimental LT-induced effects is of significant agricultural and economic importance in subtropical regions. This study investigated the effects of exogenous salicylic acid (SA, 2 mM) on the antioxidant system, fatty acid components, degree of unsaturation, and fatty acid desaturases (FADs) gene expression in pitaya seedlings (‘Taiwan No. 6’) under LT stress. LT stress increased reactive oxygen species (ROS), malondialdehyde (MDA), and relative electrical conductivity (REC), causing visible chilling injury (CI = 0.63). Crucially, LT also elevated saturated fatty acids (C12:0, C16:0, C18:0, C22:0) and decreased unsaturated fatty acids (C16:1, C18:2). This reduced the unsaturation ratio (UFA/SFA) and double bond index (DBI), compromising membrane stability and increasing permeability. However, SA application effectively mitigated these effects. SA improved peroxidase (POD) and catalase (CAT) activities, scavenging ROS and preventing oxidative damage. Crucially, SA upregulated the expression of genes encoding stearoyl-ACP desaturase (SAD) and fatty acid desaturases (FAD) enzymes, such as HuSAD2 , HuFAD2 , HuFAD4 , HuFAD6 . Consequently, SA increased unsaturated fatty acid proportions (C16:1, C18:2), UFA/SFA, and DBI. This restored membrane stability and integrity, lowered MDA, REC, and markedly reduced CI (to 0.38). This study demonstrates, for the first time in pitaya, that exogenous SA enhances cold resistance by activating antioxidant systems and regulating HuSADs and HuFADs gene expression to maintain membrane fatty acid unsaturation.