Cardiovascular health and cancer mortality: evidence from US NHANES and UK Biobank cohort studies.

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.

Transcriptome analysis reveals the promoting effects of exogenous melatonin on the selenium uptake in grape under selenium stress.

Introduction: Exogenous melatonin (MT) can promote horticultural crops growth under stress conditions. Methods: In this study, the effects of exogenous MT on the accumulation of selenium (Se) in grape were studied under Se stress. Results and discussion: Under Se stress, exogenous MT increased the biomass, content of photosynthetic pigments and antioxidant enzyme activity of grapevines. Compared with Se treatment, MT increased the root biomass, shoot biomass, chlorophyll a content, chlorophyll b content, carotenoids, superoxide dismutase activity, and peroxidase activity by 18.11%, 7.71%, 25.70%, 25.00%, 25.93%, 5.73%, and 9.41%, respectively. Additionally, MT increased the contents of gibberellin, auxin, and MT in grapevines under Se stress, while it decreased the content of abscisic acid. MT increased the contents of total Se, organic Se and inorganic Se in grapevines. Compared with Se treatment, MT increased the contents of total Se in the roots and shoots by 48.82% and 135.66%, respectively. A transcriptome sequencing analysis revealed that MT primarily regulated the cellular, metabolic, and bioregulatory processes of grapevine under Se stress, and the differentially expressed genes (DEGs) were primarily enriched in pathways, such as aminoacyl-tRNA biosynthesis, spliceosome, and flavonoid biosynthesis. These involved nine DEGs and nine metabolic pathways in total. Moreover, a field experiment showed that MT increased the content of Se in grapes and improved their quality. Therefore, MT can alleviate the stress of Se in grapevines and promote their growth and the accumulation of Se.

Soluble sugar, organic acid and phenolic composition and flavor evaluation of plum fruits.

Plums (Prunus salicina and Prunus domestica) are prevalent in southwestern China, and have attracted interest owing to their delectable taste and exceptional nutritional properties. Therefore, this study aimed to investigate the nutritional and flavor properties of plum to improve its nutritional utilization. Specifically, we determined the soluble sugars, organic acids, and phenolic components in 86 accessions using high-performance liquid chromatography. Notably, glucose, fructose, malic, and quinic acids were the predominant sweetness and acidity in plums, with sucrose contributing more to the sweetness of the flesh than the peel. Moreover, The peel contains 5.5 fold more phenolics than flesh, epicatechin, gallic acid, and proanthocyanidins C1 and B2 were the primary sources of astringency. Correlation and principal component analyses showed eight core factors for plum flavor rating, and a specific rating criterion was established. Conclusively, these findings provide information on the integrated flavor evaluation criteria and for enhancing optimal breeding of plums.

Effects of tea infusion on selenium uptake in grapevine.

Increased selenium (Se) content in fruits can supply Se in human body, but the effects of teas on the Se uptake in fruit trees are unknown. The effects of infusions of four teas (green, black, dark, and white) on the Se uptake of grapevine were studied to promote the Se uptake in fruit trees in this study. However, only black tea infusion increased the biomass, photosynthetic pigment content, superoxide dismutase (SOD) activity, peroxidase (POD) activity, and soluble protein content of grapevine. Except for white tea infusion, other tea infusions also increased the catalase (CAT) activity of grapevine. Furthermore, the tea infusions increased the activities of adenosine triphosphate sulfurase (ATPS) and adenosine 5'-phosphosulfate reductase (APR), and decreased the activities of serine acetyltransferase (SAT) and selenocysteine methyltransferase (SMT). Only the dark and white tea infusions increased the shoot total Se content by 86.53% and 23.32%, respectively (compared with the control), and also increased the shoot inorganic Se content and shoot organic Se content. Notably, four tea infusions decreased the organic Se proportion and increased the inorganic Se proportion in grapevine. Correlation and grey relational analyses showed that the root total Se content, ATPS activity, and ARP activity were closely associated with the shoot total Se content. The principal component and cluster analyses also showed that the ATPS activity, APR activity, root total Se content, and shoot total Se content were classified into one category. These findings show that black tea infusion can promote grapevine growth, while dark and white tea infusions can promote the Se uptake in grapevine.

Associations between leisure-time physical activity and the prevalence and incidence of osteoporosis disease: Cross-sectional and prospective findings from the UK biobank.

BACKGROUND: Previous studies underscore the protective role of physical activity (PA) in bone health, yet the relationship between different PA categories and osteoporosis risk remains less explored. Understanding the relationships helps tailor health recommendations and policies to maximize the effects of preventing osteoporosis. METHODS: The cross-sectional study involves 488,403 UK Biobank participants with heel quantitative ultrasound-estimated bone mineral density (eBMD) data. The longitudinal cohort involves 471,394 UK Biobank participants without initial osteoporosis and with follow-up records. PA exposure categories in our study included sedentary behavior (SB), total PA (TPA), and different category-specific PA including household, leisure, and work PA. The cases of osteoporosis were assessed using the International Classification of Diseases, 10th revision (ICD-10). The linear, logistic, and Cox proportional hazard regression models were used in our study. RESULTS: In the cross-sectional study, 15,818 (3.28 %) participants had osteoporosis. TPA levels have a positive correlation with eBMD and a negative correlation with osteoporosis prevalence. Among different categories of PA, higher levels of leisure PA were correlated with increased eBMD and a lower osteoporosis risk (leisure PA: OR: 0.83, 95 % CI: 0.79 to 0.86;). In the longitudinal study, 16,058 (17.6 % male, 82.4 % female) (3.41 %) individuals developed osteoporosis during an average follow-up of 13 years. We observed consistent protective effects of high levels of PA on osteoporosis incidence risk, particularly within the category of leisure PA (TPA: HR: 0.78, 95 % CI: 0.74 to 0.82; leisure PA:HR: 0.83, 95 % CI: 0.80 to 0.87). Such associations are independent of genetic predisposition, with no evidence of gene-PA interactions, and keep steady among individuals using drugs affecting bone-density. Moreover, among different leisure PA items, strenuous sports, other exercises, and walking for pleasure conferred a substantial protective effect against osteoporosis. Additionally, non-elderly individuals and males exhibited lower osteoporosis risk from PA. CONCLUSION: This study highlights activity categories differently associated with the risk of osteoporosis. Adherence to frequent leisure PA may have a protective effect against osteoporosis. Such associations are independent of genetic susceptibility to osteoporosis and keep steady among individuals using drugs affecting bone-density. This highlights that leisure PA could be suggested as a more effective intervention in the primary prevention of osteoporosis.

Artificial sweeteners and risk of incident cardiovascular disease and mortality: evidence from UK Biobank.

BACKGROUND: Artificial sweeteners are widely popular worldwide as substitutes for sugar or caloric sweeteners, but there are still several important unknowns and controversies regarding their associations with cardiovascular disease (CVD). We aimed to extensively assess the association and subgroup variability between artificial sweeteners and CVD and CVD mortality in the UK Biobank cohort, and further investigate the modification effects of genetic susceptibility and the mediation role of type 2 diabetes mellitus (T2DM). METHODS: This study included 133,285 participants in the UK Biobank who were free of CVD and diabetes at recruitment. Artificial sweetener intake was obtained from repeated 24-hour diet recalls. Cox proportional hazard models were used to estimate HRs. Genetic predisposition was estimated using the polygenic risk score (PRS). Furthermore, time-dependent mediation was performed. RESULTS: In our study, artificial sweetener intake (each teaspoon increase) was significantly associated with an increased risk of incident overall CVD (HR1.012, 95%CI: 1.008,1.017), coronary artery disease (CAD) (HR: 1.018, 95%CI: 1.001,1.035), peripheral arterial disease (PAD) (HR: 1.035, 95%CI: 1.010,1.061), and marginally significantly associated with heart failure (HF) risk (HR: 1.018, 95%CI: 0.999,1.038). In stratified analyses, non-whites were at greater risk of incident overall CVD from artificial sweetener. People with no obesity (BMI < 30 kg/m2) also tended to be at greater risk of incident CVD from artificial sweetener, although the obesity interaction is not significant. Meanwhile, the CVD risk associated with artificial sweeteners is independent of genetic susceptibility, and no significant interaction exists between genetic susceptibility and artificial sweeteners in terms of either additive or multiplicative effects. Furthermore, our study revealed that the relationship between artificial sweetener intake and overall CVD is significantly mediated, in large part, by prior T2DM (proportion of indirect effect: 70.0%). In specific CVD subtypes (CAD, PAD, and HF), the proportion of indirect effects ranges from 68.2 to 79.9%. CONCLUSIONS: Our findings suggest significant or marginally significant associations between artificial sweeteners and CVD and its subtypes (CAD, PAD, and HF). The associations are independent of genetic predisposition and are mediated primarily by T2DM. Therefore, the large-scale application of artificial sweeteners should be prudent, and the responses of individuals with different characteristics to artificial sweeteners should be better characterized to guide consumers' artificial sweeteners consumption behavior.

Effects of different rootstocks grafting on selenium accumulation in Cyphomandra betacea Sendt. seedlings under selenium-contaminated soil.

The effects of rootstocks tomato (Solanum lycopersicum L.), eggplant (Solanum melongena L.), and nightshade (Solanum nigrum L.) grafting on the growth and selenium (Se) accumulation of Cyphomandra betacea Sendt. seedlings were studied to identify the most suitable rootstock for increasing Se uptake of fruit trees grown in Se-contaminated soil. The rootstocks of tomato, eggplant, and nightshade grafting increased the scion biomass of C. betacea seedlings by 146.1%, 23.2%, and 94.5%, respectively, compared with the un-grafted seedlings. Moreover, tomato, eggplant, and nightshade rootstocks grafting increased the photosynthesis, superoxide dismutase activity, and peroxidase activity, while reducing the catalase activity and soluble protein content of C. betacea seedlings. Although all three rootstocks grafting decreased Se contents in rootstock roots and stems, only nightshade rootstock grafting increased Se content in the scions of C. betacea seedlings. Notably, root biomass, catalase activity, soluble protein content, rootstock root Se content, and rootstock stem Se content were closely related to the scion Se content. These findings suggest that only grafting onto nightshade rootstock significantly enhances Se uptake in C. betacea, whereas tomato and eggplant rootstocks grafting have no effect on Se uptake.

This study shows that under selenium (Se)-contaminated soil conditions, tomato, eggplant, and nightshade rootstocks can promote the growth of C. betacea seedlings and improve their stress resistance. The nightshade rootstock stands out for its ability to promote Se uptake in C. betacea seedlings, suggesting its suitability as a promising rootstock to enhance both growth and Se uptake in C. betacea.

The Relationship Between Insulin Resistance Indicated by Triglyceride and Glucose Index and Left Ventricular Hypertrophy and Decreased Left Ventricular Diastolic Function with Preserved Ejection Fraction.

Aim: The evidence on the association between insulin resistance (IR) and the prevalence or incidence of cardiac dysfunction has been controversial, and the relationship between pre-diabetic IR and cardiac function is lacking. Large sample studies in the Chinese general population are urgently needed to explore the association between IR and the risk of left ventricular hypertrophy (LVH) and decreased left ventricular diastolic function with preserved ejection fraction (LVDFpEF). Methods: Based on a National Health Check-up database in China, we conducted a multicenter cross-sectional retrospective study in 344,420 individuals. Furthermore, at a single center, we performed two retrospective longitudinal studies encompassing 8270 and 5827 individuals to investigate the association between IR and the development of new-onset LVH and LVDFpEF, respectively. The median follow-up duration exceeded 2.5 years. The triglyceride and glucose (TyG) index, known for its high sensitivity in detecting IR, serves as a reliable alternative marker of IR. The logistic and cox proportional hazard regression models were used to determine the relationships. Results: In the cross-sectional study, IR showed a positive association with the prevalence of LVH and decreased LVDFpEF after adjusting for confounders. In the longitudinal cohort, IR was also correlated with the new onset of LVH and decreased LVDFpEF, with hazard ratios (HR) of 1.986 (95% CI: 1.307, 3.017) and 1.386 (95% CI: 1.167, 1.647) in the fourth quartile of TyG levels compared to the lowest quartile, respectively, after adjusting for confounders. The subgroup analysis in non-hypertensive or non-diabetic people and the sensitivity analysis in the population with homeostasis model assessment of insulin resistance (HOMA-IR) further verified the above-mentioned results. Conclusion: IR was associated with LVH and decreased LVDFpEF. Effective management of IR may prevent or delay the development of adverse LVH and decreased LVDFpEF.

Exogenous indole-3-acetic acid promotes the plant growth and accumulation of selenium in grapevine under selenium stress.

To alleviate the selenium (Se) stress in fruit trees and improve its accumulation, the effects of exogenous indole-3-acetic acid (IAA) on the growth and Se accumulation of grapevine under Se stress were studied. The application of exogenous IAA increased the biomass of grapevine, and the concentration of exogenous IAA had a regression relationship with the biomass. The root and shoot biomass were the maximum at 60 mg L- 1 IAA, increasing by 15.61% and 23.95%, respectively, compared with the control. Exogenous IAA also increased the photosynthetic pigments and the activities of superoxide dismutase and peroxidase in grapevine. Moreover, exogenous IAA increased the contents of total Se, organic Se, and inorganic Se, and the concentration of exogenous IAA had a regression relationship with the total Se content. The highest contents of root total Se and shoot total Se were accumulated at 90 mg L- 1 IAA, increasing by 29.94% and 55.77% respectively,. In addition, the correlation and path analyses revealed that the carotenoid content and root total Se content were closely associated with the shoot total Se content. Therefore, the application of exogenous IAA can alleviate the stress of Se to grape and promote its uptake and the most effective amount for the uptake of Se is 90 mg L- 1 IAA.

Effects of Potassium-Containing Fertilizers on Sugar and Organic Acid Metabolism in Grape Fruits.

To identify suitable potassium fertilizers for grape (Vitis vinifera L.) production and study their mechanism of action, the effects of four potassium-containing fertilizers (complex fertilizer, potassium nitrate, potassium sulfate, and potassium dihydrogen phosphate) on sugar and organic acid metabolism in grape fruits were investigated. Potassium-containing fertilizers increased the activity of sugar and organic acid metabolism-related enzymes at all stages of grape fruit development. During the later stages of fruit development, potassium-containing fertilizers increased the total soluble solid content and the sugar content of the different sugar fractions and decreased the titratable acid content and organic acid content of the different organic acid fractions. At the ripening stage of grape fruit, compared with the control, complex fertilizer, potassium nitrate, potassium sulfate, and potassium dihydrogen phosphate increased the total soluble solid content by 1.5, 1.2, 3.5, and 3.4 percentage points, decreased the titratable acid content by 0.09, 0.06, 0.18, and 0.17 percentage points, respectively, and also increased the total potassium content in grape fruits to a certain degree. Transcriptome analysis of the differentially expressed genes (DEGs) in the berries showed that applying potassium-containing fertilizers enriched the genes in pathways involved in fruit quality, namely, carbon metabolism, carbon fixation in photosynthetic organisms, glycolysis and gluconeogenesis, and fructose and mannose metabolism. Potassium-containing fertilizers affected the expression levels of genes regulating sugar metabolism and potassium ion uptake and transport. Overall, potassium-containing fertilizers can promote sugar accumulation and reduce acid accumulation in grape fruits, and potassium sulfate and potassium dihydrogen phosphate had the best effects among the fertilizers tested.

Water extract of Fagopyrum dibotrys (D. Don) Hara straw increases selenium accumulation in peach seedlings under selenium-contaminated soil.

To promote the selenium (Se) uptakes in fruit trees under Se-contaminated soil, the effects of water extract of Fagopyrum dibotrys (D. Don) Hara straw on the Se accumulation in peach seedlings under selenium-contaminated soil were studied. The results showed that the root biomass, chlorophyll content, activities of antioxidant enzymes, and soluble protein content of peach seedlings were increased by the F. dibotrys straw extract. The different forms of Se (total Se, inorganic Se, and organic Se) were also increased in peach seedlings following treatment with the F. dibotrys straw extract. The highest total shoot Se content was treated by the 300-fold dilution of F. dibotrys straw, which was 30.87% higher than the control. The F. dibotrys straw extract also increased the activities of adenosine triphosphate sulfurase (ATPS), and adenosine 5'-phosphosulfate reductase (APR) in peach seedlings, but decreased the activity of serine acetyltransferase (SAT). Additionally, correlation and grey relational analyses revealed that chlorophyll a content, APR activity, and root biomass were closely associated with the total shoot Se content. Overall, this study shows that the water extract of F. dibotrys straw can promote Se uptake in peach seedlings, and 300-fold dilution is the most suitable concentration.

The water extract of Fagopyrum dibotrys (D. Don) Hara straw promoted the selenium (Se) uptake in peach seedlings under selenium-contaminated soil. The concentration of F. dibotrys straw extract showed a quadratic polynomial regression relationship with the total root and shoot Se. Furthermore, chlorophyll a content, APR activity, and root biomass were closely associated with the total shoot Se. This study shows that water extract of F. dibotrys straw can promote Se uptake in peach seedlings, and 300-fold dilution is the most suitable concentration.

Effect of abscisic acid on selenium uptake and growth of Cyphomandra betacea Sendt. (Solanum betaceum Cav.) seedlings under selenium stress.

Improvement of selenium (Se) uptake in fruit tree can improve the source of food Se for humans. In this study, the effect of various abscisic acid (ABA) concentrations on the Se uptake in Cyphomandra betacea Sendt. (Solanum betaceum Cav.) seedlings was studied under Se stress. Only the concentration of 20 µmol/L ABA promoted the growth of C. betacea seedlings by increasing the biomass and regulating the resistance physiology under Se stress. ABA also increased the Se content in C. betacea seedlings under Se stress. The concentration of ABA at 20 µmol/L got the maximum root Se and shoot Se contents, which increased by 76.64% and 55.83%, respectively, compared with the control. Correlation and grey relational analyses showed that the peroxidase activity and proline content had the first two closest relationship with the shoot Se content. This study shows that ABA can promote the Se uptake in C. betacea under Se stress, and the concentration of 20 µmol/L ABA is the optimum for Se uptake and growth of C. betacea.

Under selenium (Se) stress, abscisic acid (ABA) promotes the Se uptake in Cyphomandra betacea Sendt. (Solanum betaceum Cav.) seedlings, but only the concentration of 20 µmol/L ABA promotes the growth of C. betacea seedlings. The shoot Se content is most closely correlated with the peroxidase activity and proline content. This study shows that ABA can promote the Se uptake in C. betacea under Se stress.

Methylation of AcGST1 Is Associated with Anthocyanin Accumulation in the Kiwifruit Outer Pericarp.

Most red-fleshed kiwifruit cultivars, such as Hongyang, only accumulate anthocyanins in the inner pericarp; the trait of full red flesh becomes the goal pursued by breeders. In this study, we identified a mutant "H-16" showing a red color in both the inner and outer pericarps, and the underlying mechanism was explored. Through transcriptome analysis, a key differentially expressed gene AcGST1 was screened out, which was positively correlated with anthocyanin accumulation in the outer pericarp. The result of McrBC-PCR and bisulfite sequencing revealed that the SG3 region (-292 to -597 bp) of AcGST1 promoter in "H-16" had a significantly lower CHH cytosine methylation level than that in Hongyang, accompanied by low expression of methyltransferase genes (MET1 and CMT2) and high expression of demethylase genes (ROS1 and DML1). Transient calli transformation confirmed that demethylase gene DML1 can activate transcription of AcGST1 to enhance its expression. Overexpression of AcGST1 enhanced the anthocyanin accumulation in the fruit flesh and leaves of the transgenic lines. These results suggested that a decrease in the methylation level of the AcGST1 promoter may contribute to accumulation of anthocyanin in the outer pericarp of "H-16".

Association between questionnaire-based and accelerometer-based physical activity and the incidence of chronic kidney disease using data from UK Biobank: a prospective cohort study.

Background: Prior studies on the relationship between chronic kidney disease (CKD) and physical activity (PA) mainly relied on subjective PA data and rarely considered the genetic risk. This study aims to thoroughly investigate this relationship by utilizing both accelerometer-measured and questionnaire-measured PA data. Methods: This prospective cohort study encompasses two cohorts from the UK Biobank. The questionnaire-based cohort involves 448,444 CKD-free participants who completed an International Physical Activity Questionnaire between 2006 and 2010 and had genetic data. PA was categorized into distinct activities: leisure, housework, job-related, and transportation. The accelerometer-based cohort involves 89,296 CKD-free participants who provided a full week of accelerometer-based physical activity data between 2013 and 2015 and had genetic data. PA was classified as light-intensity, moderate-intensity, vigorous-intensity, moderate to vigorous-intensity PA (LPA, MPA, VPA, MVPA), and total PA. Incident CKD was ascertained from linked hospital inpatient and death records. Genetic risk was assessed using polygenic risk scores. Cox proportional hazard models with restricted cubic splines were used for the analysis. Findings: In the questionnaire-based cohort, 18,184 (4.05%) participants developed CKD during 13.6 years of follow-up. Engaging in strenuous sports, other exercises, walking for pleasure, stair climbing, and heavy DIY were associated with a reduced risk of CKD. In the accelerometer-based cohort, 2297 (2.57%) participants developed CKD during 7.9 years of follow-up. Higher levels [highest quartile vs lowest quartile] of MPA (HR 0.639, 95% CI 0.554-0.737), VPA (HR 0.639, 95% CI 0.549-0.745), MVPA (HR 0.630, 95% CI 0.545-0.729), and total PA (HR 0.649, 95% CI 0.563-0.750) were associated with a lower CKD risk. There were significant interactions between MPA and genetic risk on the risk of CKD incidence (P for interaction = 0.025). A linear dose-response relationship was observed between MPA, total PA, and the risk of CKD incidence with no minimal or maximal threshold. These associations are robust in different subgroups and a series of sensitivity analyses. Interpretation: Engaging in multiple types of PA and higher levels of total PA, MPA, VPA, and MVPA may be associated with a lower risk of developing CKD, regardless of genetic risk. This finding holds substantial implications for clinical approaches to CKD prevention and provides evidence to inform future PA guideline development. Funding: Medical Science Advancement Program of Wuhan University, and the National Science Foundation of China.

Melatonin Promotes Iron Reactivation and Reutilization in Peach Plants under Iron Deficiency.

The yellowing of leaves due to iron deficiency is a prevalent issue in peach production. Although the capacity of exogenous melatonin (MT) to promote iron uptake in peach plants has been demonstrated, its underlying mechanism remains ambiguous. This investigation was carried out to further study the effects of exogenous MT on the iron absorption and transport mechanisms of peach (Prunus persica) plants under iron-deficient conditions through transcriptome sequencing. Under both iron-deficient and iron-supplied conditions, MT increased the content of photosynthetic pigments in peach leaves and decreased the concentrations of pectin, hemicellulose, cell wall iron, pectin iron, and hemicellulose iron in peach plants to a certain extent. These effects stemmed from the inhibitory effect of MT on the polygalacturonase (PG), cellulase (Cx), phenylalanine ammonia-lyase (PAL), and cinnamoyl-coenzyme A reductase (CCR) activities, as well as the promotional effect of MT on the cinnamic acid-4-hydroxylase (C4H) activity, facilitating the reactivation of cell wall component iron. Additionally, MT increased the ferric-chelate reductase (FCR) activity and the contents of total and active iron in various organs of peach plants under iron-deficient and iron-supplied conditions. Transcriptome analysis revealed that the differentially expressed genes (DEGs) linked to iron metabolism in MT-treated peach plants were primarily enriched in the aminoacyl-tRNA biosynthesis pathway under iron-deficient conditions. Furthermore, MT influenced the expression levels of these DEGs, regulating cell wall metabolism, lignin metabolism, and iron translocation within peach plants. Overall, the application of exogenous MT promotes the reactivation and reutilization of iron in peach plants.

Comparative analysis of the phenolic contents and antioxidant activities of different parts of two pomegranate (Punica granatum L.) Cultivars: 'Tunisia' and 'Qingpi'.

Pomegranate (Punica granatum L.), with its abundant phenolic substances and strong antioxidant activity, holds significant research and utilization potential across various organs. However, there have been few studies on the phenolic content and antioxidant activity of different parts of pomegranate, especially the placenta. This study investigated the phenolic content and antioxidant activity of fruits, flowers, and leaves of two pomegranate varieties, 'Tunisia' and 'Qingpi', throughout their growth and development. Results indicated significant variations in phenolic content among different organs, with petals exhibiting the highest total polyphenol content (TPC, 49.40 mg GAE/g FW) and total anthocyanin content (TMAC, 1938.54 nmol/g FW). Placenta contained the highest levels of total flavonoids (TFC, 173.58 mg RE/g FW) and punicalagin (109.30 mg/g FW). The peel had the highest content of total flavanols (TFAC, 19.42 mg CE/g FW). Over the course of pomegranate development, total polyphenols, total flavonoids, total flavanols, punicalagin, and antioxidant activity declined in different organs. Antioxidant activity followed the order: fruit > flower > leaf, with the placenta exhibiting the highest antioxidant activity among fruits. Antioxidant activity showed a significant positive correlation with total polyphenols (R2 = 0.77-1.00), total flavonoids (R2 = 0.71-0.99, except tegmens), and punicalagin (R2 = 0.71-1.00). This study provides a comparative analysis of the phenolic content and antioxidant activity in different organs of pomegranate, highlighting the placenta as the primary source of punicalagin. This study provides a theoretical basis for the development and utilization of pomegranate phenolic compounds.

Effects of exogenous melatonin on sugar and organic acid metabolism in early-ripening peach fruits.

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.

Transcriptome Profiles Reveal the Promoting Effects of Exogenous Melatonin on Fruit Softening of Chinese Plum.

In this study, we investigated the effect of exogenous melatonin (MT) on cell wall metabolism leading to Chinese plum (Prunus salicina Lindl.) fruit softening. Exogenous MT treatment increased the endogenous MT content in plum fruits before fruit ripening. However, in mature plum fruits, exogenous MT treatment decreased the fruit hardness, pulp hardness, fruit elasticity, contents of ion-bound pectin, covalently-bound pectin, hemicellulose, and cellulose, and activities of xyloglucan endotransglycosylase/hydrolase and endo-ß-1,4-glucanase, and increased the water-soluble pectin content, and activities of pectin methyl esterase, pectin lyase, polygalacturonase, ß-galactopyranosidase, and α-L-arabinofuranosidase. Transcriptome analysis revealed that the differentially expressed genes (DEGs) associated with cell wall metabolism in the exogenous MT-treated plum fruits were mainly enriched in the pentose and glucuronate interconversions, phenylpropanoid biosynthesis, cyanoamino acid metabolism, and galactose metabolism pathways. Analysis of these DEGs revealed that exogenous MT treatment affected the expression of genes regulating the cell wall metabolism. Overall, exogenous MT treatment promotes the fruit softening of Chinese plum.

Foliar application of salicylic acid inhibits the cadmium uptake and accumulation in lettuce (Lactuca sativa L.).

Introduction: Salicylic acid (SA) is a multi-functional endogenous phytohormone implicated in the growth, development, and metabolism of many plant species. Methods: This study evaluated the effects of different concentrations of SA (0, 25, 100, 200, and 500 mg/L) on the growth and cadmium (Cd) content of lettuce (Lactuca sativa L.) under Cd stress. The different concentrations of SA treatments were administered through foliar application. Results: Our results showed that 100-200 mg/L SA significantly increased the plant height and biomass of lettuce under Cd stress. When SA concentration was 200 mg/L, the plant height and root length of lettuce increased by 19.42% and 22.77%, respectively, compared with Cd treatment alone. Moreover, 200 mg/L and 500mg/L SA concentrations could reduce peroxidase (POD) and superoxide dismutase (SOD) activities caused by Cd stress. When the concentration of exogenous SA was 500 mg/L, the POD and SOD activities of lettuce leaves decreased by 15.51% and 19.91%, respectively, compared with Cd treatment. A certain concentration of SA reduced the uptake of Cd by the lettuce root system and the transport of Cd from the lettuce root system to shoots by down-regulating the expression of Nramp5, HMA4, and SAMT, thus reducing the Cd content of lettuce shoots. When the concentration of SA was 100 mg/L, 200 mg/L, and 500 mg/L, the Cd contents of lettuce shoots were 11.28%, 22.70%, and 18.16%, respectively, lower than that of Cd treatment alone. Furthermore, principal component and correlation analyses showed that the Cd content of lettuce shoots was correlated with plant height, root length, biomass, antioxidant enzymes, and the expression level of genes related to Cd uptake. Discussion: In general, these results provide a reference for the mechanism by which SA reduces the Cd accumulation in vegetables and a theoretical basis for developing heavy metal blockers with SA components.

Genome-wide identification of the AcMADS-box family and functional validation of AcMADS32 involved in carotenoid biosynthesis in Actinidia.

MADS-box is a large transcription factor family in plants and plays a crucial role in various plant developmental processes; however, it has not been systematically analyzed in kiwifruit. In the present study, 74 AcMADS genes were identified in the Red5 kiwifruit genome, including 17 type-I and 57 type-II members according to the conserved domains. The AcMADS genes were randomly distributed across 25 chromosomes and were predicted to be mostly located in the nucleus. A total of 33 fragmental duplications were detected in the AcMADS genes, which might be the main force driving the family expansion. Many hormone-associated cis-acting elements were detected in the promoter region. Expression profile analysis showed that AcMADS members had tissue specificity and different responses to dark, low temperature, drought, and salt stress. Two genes in the AG group, AcMADS32 and AcMADS48, had high expression levels during fruit development, and the role of AcMADS32 was further verified by stable overexpression in kiwifruit seedlings. The content of α-carotene and the ratio of zeaxanthin/ß-carotene was increased in transgenic kiwifruit seedlings, and the expression level of AcBCH1/2 was significantly increased, suggesting that AcMADS32 plays an important role in regulating carotenoid accumulation. These results have enriched our understanding of the MADS-box gene family and laid a foundation for further research of the functions of its members during kiwifruit development.