Effects of Exogenous Nitric Oxide Treatment on Grape Berries Against Botrytis cinerea and Alternaria alternata Related Enzymes and Metabolites.

Postharvest losses of grape berries caused by the pathogenic fungi Botrytis cinerea and Alternaria alternata have been widely reported, and nitric oxide (NO) as a plant signaling molecule to control postharvest diseases has recently become an active research topic. This study aimed to investigate the regulatory effect of NO on the interaction between grape berries and fungi. During interactions between grape berries and pathogenic fungi, treatment with 10 mM sodium nitroprusside (SNP, an NO donor) delayed the decline of the physiological quality of the grape berries and had positive effects on the weight loss rate, firmness, and respiration intensity. SNP treatment increased the activities of superoxide dismutase (SOD) and polyphenol oxidase (PPO) and inhibited the activities of peroxidase (POD) and catalase (CAT) of grape berries during the resistance to fungal pathogen infection. In addition, the increase in browning degree and the accumulation of hydrogen peroxide were inhibited by SNP treatment. In the phenylpropane metabolic pathway, the activities of phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H), and 4-coumaric acid coenzyme A ligase (4CL) were increased during the activation of grape berries during the resistance to pathogen infection by SNP, and the intermediate metabolites lignin, flavonoids, and total phenols were accumulated. In addition, SNP treatment had a regulatory effect on the gene expression levels of SOD, POD, PPO, PAL, and 4CL. These results suggested that SNP treatment was effective for the preservation and disease reduction of grape berries.

Clinical features of anemia in membranous nephropathy patients: a Chinese cohort study.

BACKGROUND: Anemia is a common complication in patients with progressive chronic kidney disease. This cohort study evaluated the prevalence, clinical features and prognosis of membranous nephropathy (MN) with anemia. METHODS: We retrospectively analyzed a cohort of MN patients diagnosed using renal biopsy between February 2012 and February 2018. The clinical and pathological characteristics at baseline were recorded, and the outcomes (hemoglobin, proteinuria and renal function) during follow-ups were also evaluated. Univariate and multivariate logistic regression analyses were performed to identify the independent risk factors for anemia in MN patients. The MN patients were divided according to the therapeutic effect they experienced as follows: without-anemia, completely corrected anemia, standard anemia treatment and nonstandard anemia treatment groups. We compared the rate of complete remission of MN and renal end-point events among the four groups. RESULTS: The median age of 483 patients was 42.43 (26.59, 50.20) years at the time of MN diagnosis. The prevalence of anemia at baseline was 23.81%, and the cumulative prevalence was 50.72%. There were 133 cases of mild anemia, 103 cases of moderate anemia and 9 cases of severe anemia; in addition, there were 228 cases of normocytic anemia and 17 cases of microcytic hypochromic anemia. Multivariate logistic regression indicated that acute renal tubule injury >5% (OR = 1.634, 95% CI 1.034, 2.581; p = 0.035), total protein level (OR = 0.949, 95% CI 0.923, 0.975; p < 0.001), cholesterol level (OR = 0.833, 95% CI 0.749, 0.926, p = 0.001), hypokalemia (OR = 2.612, 95% CI 1.227, 5.560, p = 0.013) and hypophosphatemia (OR = 2.653, 95% CI 1.303, 5.403, p = 0.007) were independent risk factors for anemia in MN patients. The complete remission rate of MN patients without anemia was significantly higher than that of anemia patients who exhibited treatment failure. The incidence of renal endpoint events was different among the four groups. CONCLUSION: The anemia experienced by MN patients is mainly mild and moderate, normocytic anemia. The pathological features of acute renal tubular injury and clinical nutritional status are independent risk factors for anemia. There were differences in renal prognosis among anemia patients with different treatment outcomes.

Comparison of two mainstream endometrial preparation regimens in vitrified-warmed embryo transfers after PGT.

RESEARCH QUESTION: Which of the two mainstream endometrial preparation regimens, assisted natural cycle (NC) or hormone replacement treatment cycle (HRT), help frozen-thawed embryo transfer (FET) cycles after preimplantation genetic testing (PGT) achieve better clinical outcomes? DESIGN: This retrospective analysis included 3400 vitrified-warmed single blastocyst transfer cycles after PGT from January 2011 to November 2020, and involved 2332 patients with regular menstrual cycles. The decision to proceed with an assisted NC (n = 827) or HRT (n = 2573) before FET was reached based on a combination of patient preference and physician guidance. Clinical pregnancy rate, live birth rate, early miscarriage rate and obstetric outcomes were compared. RESULTS: No significant difference was observed between the assisted NC and HRT groups in terms of clinical pregnancy rate (51.6% versus 50.7%, P = 0.634), live birth rate (44.0% versus 43.4%, P = 0.746) or early miscarriage rate (12.6% versus 12.0%, P = 0.707). Multivariate analysis indicated that the endometrial preparation protocol was not an independent factor for a clinical pregnancy or live birth. In the HRT group, the Caesarean section rate (64.7% versus 51.9%, P < 0.001) and pregnancy complication rate (20.2% versus 13.8%, P = 0.003) were significantly higher. The two groups were not statistically different with respect to gestational age, early preterm birth rate, fetal weight or fetal birth defect rate. CONCLUSIONS: For patients undergoing a PGT-FET cycle involving a single blastocyst transfer, using assisted NC and HRT for the endometrial preparation could lead to comparable rates of clinical pregnancy and live birth. Additionally, NC is safer than HRT in terms of avoiding pregnancy complications and adverse obstetric outcomes.

Biological Functions of Hydrogen Sulfide in Plants.

Hydrogen sulfide (H2S), which is a gasotransmitter, can be biosynthesized and participates in various physiological and biochemical processes in plants. H2S also positively affects plants' adaptation to abiotic stresses. Here, we summarize the specific ways in which H2S is endogenously synthesized and metabolized in plants, along with the agents and methods used for H2S research, and outline the progress of research on the regulation of H2S on plant metabolism and morphogenesis, abiotic stress tolerance, and the series of different post-translational modifications (PTMs) in which H2S is involved, to provide a reference for future research on the mechanism of H2S action.

Regulation of the biosynthesis of endogenous nitric oxide and abscisic acid in stored peaches by exogenous nitric oxide and abscisic acid.

BACKGROUND: Nitric oxide (NO) and abscisic acid (ABA) are important regulators of plant response to cold stress, and they interact in response to cold signals. The primary goal of this study was to determine the roles of exogenous NO and ABA on the synthesis of endogenous NO and ABA in cold-stored peach fruit. RESULTS: Exogenous NO and ABA maintained a relatively high content of NO, increased nitrate reductase (NR) activity, and inhibited the activity of NO synthase (NOS)-like and the levels of polyamine biosynthesis in peaches during cold storage. Treatments of potassium 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO), NO, N-nitro-l-Arg-methyl ester (L -NAME), and sodium tungstate did not influence ABA content. Exogenous ABA increased the content of carotenoids and the activities of aldehyde oxidase (AO), 9-cis-epoxycarotenoid dioxygenase (NCED), and zeaxanthin epoxidase (ZEP) of ABA synthesis in peaches during cold storage, and upregulated the gene expression of PpAO1, PpNCED1, PpNCED2, and PpZEP. The production of endogenous NO was differentially inhibited by NO scavengers, ABA inhibitors, and NR inhibitors, but not affected by NOS-like inhibitors during cold storage. CONCLUSION: Exogenous NO and ABA can induce endogenous NO synthesis in cold-stored peaches by the nitrate reductase pathway, and ABA can mediate endogenous ABA synthesis by the autocatalytic reaction. NO does not regulate ABA synthesis. © 2019 Society of Chemical Industry.

Multibranch Gold Nanoparticles as Surface-Enhanced Raman Spectroscopy Substrates for Rapid and Sensitive Analysis of Fipronil in Eggs.

A sensitive strategy to rapidly detect fipronil residues in eggs using multibranch gold nanoparticles (AuNPs) as the substrate of surface-enhanced Raman spectroscopy (SERS) was investigated in this study. Under optimized conditions, fipronil molecules preferentially deposited on the multibranch gold nanoparticles with preferential (111) facet-oriented growth due to its low surface energy. This anisotropic growth promoted the increase of SERS "hot spots", inducing a huge enhancement of Raman signals of the fipronil. An external standard calibration method was employed for quantitative analysis, and the method was validated for linearity, sensitivity, repeatability and recovery. Good linearity were found in the concentration range of 10 ng/L~10 mg/L in fipronil acetone solution (R2 = 0.9916) and 8 × 10-5 mg/m2 to 0.8 mg/m2 on eggshells (R2 = 0.9906), respectively. The recovery rate based on acetone recovered fipronil on eggshells and in egg liquids was 80.13%~87.87%, and 81.34%~88.89%, respectively. The SERS assay was successfully used to monitor fipronil in eggs.

Interactive effects of abscisic acid and nitric oxide on chilling resistance and active oxygen metabolism in peach fruit during cold storage.

BACKGROUND: Cold conditions can accelerate the production of reactive oxygen species (ROS), and excessive ROS may attack biological macromolecules, disrupt related signal pathways, induce oxidative stress and influence plant metabolism. The cross-talk between nitric oxide (NO) and abscisic acid (ABA) and the inhibitions by NO or ABA on oxidative damage have been reported in fruits. However, there are few reports about the roles of NO-ABA interactions in chilling stress and antioxidant defense in fruits during cold storage. This study was conducted to investigate the roles of NO, ABA and interactions between NO and ABA in response to chilling stress on peach fruit (Prunus persica (L.) Batsch, cv. 'Xintaihong'). RESULTS: Treatments with 15 µmol L-1 NO, 100 µmol L-1 ABA and 15 µmol L-1 NO + 5 mmol L-1 sodium tungstate solution could reduce ROS content, alleviate lipid peroxidation and enhance antioxidant enzyme activities and antioxidant capacities. However, treatments with 5 µmol L-1 potassium 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO), 5 mmol L-1 sodium tungstate and 100 µmol L-1 ABA + 5 µmol L-1 c-PTIO differentially blocked these protective effects and significantly increased ROS content and lipid peroxidation of peaches under low-temperature conditions. CONCLUSIONS: Application of exogenous ABA could increase the resistance to cold-induced oxidative stress by enhancing the efficiency of enzymatic and non-enzymatic systems, which were partially mediated by NO. © 2018 Society of Chemical Industry.

Synergistic effects of ascorbic acid and plant-derived ceramide to enhance storability and boost antioxidant systems of postharvest strawberries.

BACKGROUND: Excessive reactive oxygen species (ROS) may attack biological macromolecules and induce oxidative stress. The inhibition by ascorbic acid (AsA) on oxidative damage has been reported in fruits, while the barrier effect of ceramide has also been proven. However, there are few reports about the effects of ceramide-AsA interactions to enhance storability and boost antioxidant systems in fruits during storage. This study was conducted to study the synergistic effects of AsA in combination with ceramide on the quality of postharvest strawberry (Fragaria anannasa cv. Tianbao). RESULTS: Treatment with 100 mg L-1 AsA plus 1.2 mmol L-1 ceramide significantly delayed the rot of strawberries, reduced the water loss and the contents of ROS, malonaldehyde (MDA), and proline, however, increased the contents of total flavonoids, total phenols, and anthocyanins compared with other treatments. Also, treatment with 100 mg L-1 AsA plus 1.2 mmol L-1 ceramide significantly increased the activities of peroxidase (POD) and superoxide dismutase (SOD) but inhibited the activity of polyphenol oxidase (PPO). CONCLUSION: It is suggested that treatment with 100 mg L-1 AsA plus 1.2 mmol L-1 ceramide could significantly reduce the oxidative damage and maintain the storage quality of strawberries during storage by enhancing the antioxidant systems. © 2019 Society of Chemical Industry.

Exogenous nitric oxide induces disease resistance against Monilinia fructicola through activating the phenylpropanoid pathway in peach fruit.

BACKGROUND: Nitric oxide (NO) is a multifunctional signaling molecule involved in plant-induced resistance to disease. The present study aimed to investigate the relationship between disease resistance induced by NO and the phenylpropanoid pathway in peach fruit. The present study investigated the effect of NO on the main enzymes and metabolites of the phenylpropanoid pathway of harvested peach, which are probably related to disease resistance against Monilinia fructicola. RESULTS: The results showed that treatment with 15 µmol L-1 NO significantly (P < 0.05) enhanced the activities of phenylalanine ammonia-lyase, cinnamate-4-hydroxylase, 4-coumaroyl-CoA ligase, chalcone synthase and chalcone isomerase and the expression of their genes. Furthermore, NO treatment significantly (P < 0.05) increased the contents of total phenolics, flavonoids and lignin over the entire storage period and maintained higher total anthocyanin, phenolic acid and anthocyanin contents during the earlier storage period. CONCLUSION: These results suggest that NO treatment could activate the phenylpropanoid pathway to enhance the activity of related enzymes and the contents of phenylpropanoid metabolites in peach to improve disease resistance and prevent pathogenic invasion. © 2016 Society of Chemical Industry.

Effects of nitric oxide on mitochondrial oxidative defence in postharvest peach fruits.

BACKGROUND: It has been confirmed that the accumulation of reactive oxygen species (ROS) in fruit can cause oxidative damage and nitric oxide (NO) can regulate the accumulation of ROS and the antioxidative defence of fruit. However, little is known about the roles of NO on the antioxidant system in mitochondria of fruit. In this study, Feicheng peach fruits were dipped with 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO) and NO solutions to explore the effects of NO on the membrane permeability transition and antioxidant system in mitochondria of peach fruit. RESULTS: Treatment with 15 µmol L(-1) NO solution could delay the decrease of mitochondrial permeability transition and decrease the content of ROS in mitochondria. Besides, when the endogenous NO was scavenged by c-PTIO, the ROS in mitochondria increased greatly and superoxide dismutase activity decreased, while the content and activities of peroxidase and catalase changed slightly. CONCLUSION: By delaying the decrease of mitochondrial permeability transition, 15 µmol L(-1) NO treatment could promote a more stable internal medium in mitochondria of Feicheng peach fruit. The increases in the activities of antioxidant enzymes in mitochondria caused by the remove of endogenous NO suggested that NO also plays an important role in the mitochondrial antioxidant system of Feicheng peach fruit.

The association between the change in severity score from baseline and the outcomes of critically ill patients was enhanced by integration of bioimpedance analysis parameters.

The study of the outcomes of critically ill patients has been a hard stuff in the field of intensive care. To explore the relationship between changes of severity scores, bioelectrical impedance analysis (BIA) and outcomes of critically ill patients, we enrolled patients (n = 206) admitted to intensive care unit (ICU) in Jinling Hospital from 2018 to 2021 with records of BIA on the days 1- and 3- ICU. Collected BIA and clinical data including simplified acute physiology score II (SAPS II) and sequential organ failure assessment. According to the baseline and change of severity scores or phase angle (PA) values, the patients were divided into: G-G, baseline good status, 3rd day unchanged; G-B, baseline good status, 3rd day deteriorated; B-G, baseline bad status, 3rd day improved; and B-B, baseline bad status, 3rd day unchanged. According to PA, the mortality of group G-G was 8.6%, and it was greater than 50% in group B-B for severity scores. The new score combining PA and severity scores established. Multivariate logistic regression analysis revealed that PA-SAPS II score was the only independent factor for 90-day mortality (P < 0.05). A linear correlation was found between mortality and PA-SAPS II score (prediction equation: Y ( % ) = 16.97 × X - 9.67 , R2 = 0.96, P < 0.05).

Highly flexible carbon nitride-polyethylene glycol-cellulose acetate film with photocatalytic antibacterial activity for fruit preservation.

Cellulose acetate film, as a biodegradable and biomass-derived material, has great potential applications in food packaging. However, the poor mechanical and antibacterial properties limit its applications. Herein, a highly flexible carbon nitride-polyethylene glycol-cellulose acetate (CN-PEG-CA) film was successfully prepared by combining graphitic carbon nitride (g-C3N4) photocatalyst with cellulose acetate (CA). The g-C3N4 enables the film with antibacterial activity, as a green photocatalyst. PEG softens the rigid polymer CA and crosslinks CA, PEG, and g-C3N4 together by hydrogen bonding, as a flexible crosslinker. X-ray diffractometer (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectrum (FT-IR) characterizations confirmed the successful preparation of the CN-PEG-CA film. The mechanical property tests demonstrated that adding PEG increased the elongation at break of the film by about 4 times. The composite film had high antibacterial activity, and the bactericidal rates on Escherichia coli and Staphylococcus aureus were 99.98 % and 99.89 %, respectively. It effectively extended the shelf life of strawberries to 96 h and effectively maintained the quality of strawberries during storage. After 96 h, the weight loss rate of strawberries packaged with 15 % CN-PEG-CA film was 21.83 %, vitamin C content was 45.47 %, titratable acidity content was 0.89 %, and color, hardness and total soluble solids were well maintained. And biocompatibility test results showed that the film was safe and nontoxic. From the ecological and economic point of view, the highly flexible and biodegradable films with efficient photocatalytic antibacterial activity synthesized in this paper have great potential in the field of food packaging.

Regulation of Mitochondrial Respiration by Hydrogen Sulfide.

Hydrogen sulfide (H2S), the third gasotransmitter, has positive roles in animals and plants. Mitochondria are the source and the target of H2S and the regulatory hub in metabolism, stress, and disease. Mitochondrial bioenergetics is a vital process that produces ATP and provides energy to support the physiological and biochemical processes. H2S regulates mitochondrial bioenergetic functions and mitochondrial oxidative phosphorylation. The article summarizes the recent knowledge of the chemical and biological characteristics, the mitochondrial biosynthesis of H2S, and the regulatory effects of H2S on the tricarboxylic acid cycle and the mitochondrial respiratory chain complexes. The roles of H2S on the tricarboxylic acid cycle and mitochondrial respiratory complexes in mammals have been widely studied. The biological function of H2S is now a hot topic in plants. Mitochondria are also vital organelles regulating plant processes. The regulation of H2S in plant mitochondrial functions is gaining more and more attention. This paper mainly summarizes the current knowledge on the regulatory effects of H2S on the tricarboxylic acid cycle (TCA) and the mitochondrial respiratory chain. A study of the roles of H2S in mitochondrial respiration in plants to elucidate the botanical function of H2S in plants would be highly desirable.

Nitric oxide-mediated DNA methylation enhances cold resistance in postharvest peach fruit.

Low temperature can affect DNA methylation. Since exogenous use of NO can reduce cold damage in peach fruit during cold storage, this study investigated the roles of NO on DNA methylation of peaches suffering cold stress. The results showed that exogenous NO effectively alleviated the decrease in total DNA methyltransferase (DNMT) activity and transcript levels induced by cold stress, whereas c-PTIO exacerbated the decrease in total DNMT activity and transcript levels. Further BSP analysis of the promoter regions of four cold resistance genes (PpCBF5-IS2, PpICE1-IS, PpMYC2-IS, PpCOR-IS1) in peaches showed that in peaches treated with exogenous NO, PpCBF5-IS2 and PpICE1-IS were modified by hypermethylation, PpMYC2-IS was modified by methylation, PpCOR-IS1 was modified by demethylation and insensitive to NO. It was suggested that NO could enhance the cold resistance of postharvest peaches by mediating DNA methylation.

Nitric oxide modulates folate-mediated one-carbon metabolism and mitochondrial energy levels of peaches during cold storage.

Folate-mediated one-carbon metabolism (FOCM) is closely associated with postharvest preservation. This study investigated the effects of exogenous nitric oxide (NO) on FOCM, storage quality, energy metabolism, and mitochondrial membrane integrity in cold-storage peach fruit. In this experiment, peaches were soaked with 1.5 mmol L-1S-nitrosoglutathione (GSNO) as NO donor, and the negative treatment (NT) solution containing 5 µmol L-1 carboxy-PTIO (c-PTIO, NO scavenger), 200 µmol L-1 NG-Nitro-L-arginine methyl ester (L-NAME, NO synthase-like enzyme inhibitor), and 200 µmol L-1 sodium tungstate dihydrate (nitrate reductase inhibitor) and stored at 0°C. The results showed that NO decreased the activity of S-adenosylmethionine synthase and S-adenosylhomocysteine hydrolase and increased the activity of methionine sulfoxide reductase A, as well as the content of N5-methyl-THF, the ratio of tetrahydrofolate (THF), homocysteine, methionine, S-adenosylmethionine (SAM), and SAM to S-adenosylhomocysteine compared with the control, indicating that NO effectively increased FOCM flux by affecting the activity of FOCM enzymes. Meanwhile, NO increased the activities of H+-ATPase, Ca2+-ATPase, cytochrome c oxidase, succinate dehydrogenase, and the contents of adenosine triphosphate and adenosine diphosphate, and maintained high energy charge in peaches during storage. NO retarded the increase in mitochondrial permeability transition, reactive oxygen species content, and the decrease in mitochondrial membrane fluidity, membrane potential, and swelling. NT treatment exhibited the opposite results. In conclusion, these results suggested that NO could induce the accumulation of folate and FOCM flux and maintain mitochondrial energy levels, which might be responsible for maintaining the quality of peaches during cold storage.

Green and recyclable graphitic carbon nitride/chitosan/polyvinyl alcohol photocatalytic films with efficient antibacterial activity for fruit packaging.

Chitosan (CS) is an excellent raw material for the preparation of food packaging films due to its good film-forming properties, non-toxicity, and biodegradability. However, pure chitosan films have drawbacks such as weak mechanical properties and limited antimicrobial activity. In this work, novel food packaging films containing chitosan, polyvinyl alcohol (PVA) and porous graphitic carbon nitride (g-C3N4) were successfully prepared. The PVA served to improve the mechanical properties of the chitosan-based films, whilst the porous g-C3N4 acted as a photocatalytically-active antibacterial agent. The tensile strength (TS) and elongation at break (EAB) of the g-C3N4/CS/PVA films both increased by ~4 times compared to the pristine CS/PVA films at the optimum g-C3N4 loading of ~10 wt%. The addition of g-C3N4 increase the water contact angle (WCA) of the films from 38° to 50°, whilst decreasing the water vapor permeability (WVP) from 160 × 10-12 to 135 × 10-12 g∙Pa-1 s-1 m-1. The shelf life of strawberries covered with g-C3N4/CS/PVA films at room temperature could be extended up to 96 h, compared to 48 h and 72 h for strawberries covered with polyethylene (PE) films or CS/PVA films, respectively. The g-C3N4/CS/PVA films offered good antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Further, the composite films could be easily recycled with the regenerated films offering almost identical mechanical properties and activities as the original films. The prepared g-C3N4/CS/PVA films thus offer promise for low-cost antimicrobial packaging applications.

Nitric oxide promotes energy metabolism and protects mitochondrial DNA in peaches during cold storage.

The mitochondria are important organelles related to energy metabolism and are susceptible to oxidative damage. In this experiment, peaches (Prunus persica) were treated with distilled water (as the control), 15 µmol L-1 of nitric oxide (NO), and 20 µmol L-1 of carboxy-PTIO (NO scavenger). The changes in mitochondrial physiological indicators, energy metabolism process, and mitochondrial DNA (mtDNA) damage and repair were quantified. Compared with the control, NO treatment reduced mitochondrial oxygen consumption and the reactive oxygen species content, increased mitochondrial respiration control rate, and promoted energy metabolism by influencing the activities of citrate synthase, aconitase, isocitrate dehydrogenase, and α-ketoglutarate dehydrogenase in the tricarboxylic acid cycle and ATPase activity in peach mitochondria. NO treatment also maintained the relative copy number of mtDNA and the relative amplification of long PCR in peaches, decreased the level of 8-hydroxy-2 deoxyguanosine, and upregulated the expression of PpOGG1, PpAPE1, and PpLIG1. These results indicated that exogenous NO treatment (15 µmol L-1) could reduce mtDNA oxidative damage, maintain mtDNA molecular integrity, and inhibit mtDNA copy number reduction by reducing the reactive oxygen species content, thereby promoting mitochondrial energy metabolism and prolonging the storage life of peaches at low temperatures.

Nitric Oxide Made a Major Contribution to the Improvement of Quality in Button Mushrooms (Agaricus bisporus) by the Combined Treatment of Nitric Oxide with 1-MCP.

Browning is one of the major effects of shelf-life responsible for the reduction in the commercial value of the button mushrooms (Agaricus bisporus). In this study, the individual and the combined effects of exogenous sodium nitroprusside (SNP, a nitric oxide donor) and 1-methylcyclopropene (1-MCP) on the quality of button mushrooms were evaluated. The results demonstrated that mushrooms treated with SNP+1-MCP promoted reactive oxygen species (ROS) metabolism thereby protecting cell membrane integrity, hindering polyphenol oxidase (PPO) binding to phenolic compounds, and downregulating the PPO activity. In addition, the SNP+1-MCP treatment effectively maintained quality (firmness, color, total phenol, and flavonoid) and mitigated oxidative damage by reducing ROS accumulation and malondialdehyde production through the stimulation of the antioxidant enzymes activities and the enhancement of ascorbic acid (AsA) and glutathione (GSH) contents. Moreover, the correlation analysis validated the above results. The SNP+1-MCP treatment was observed to be more prominent on maintaining quality than the individual effects of SNP followed by 1-MCP, suggesting that the combination of NO and 1-MCP had synergistic effects in retarding button mushrooms senescence, and NO signaling molecules might be predominant in the synergy.

Short-term hypobaric treatment alleviates chilling injury by regulating membrane fatty acids metabolism in peach fruit.

Short-term hypobaric treatment (SHT) on postharvest quality and membrane fatty acids metabolism were studied in peach fruit (Prunus persica [L.] Batsch., cv. Feicheng) during shelf life after cold storage. SHT was effective in alleviating chilling injury (CI) and maintaining postharvest quality. SHT reduced the production of malondialdehyde (MDA) and electrolyte leakage (EL), and increased membrane fluidity. In addition, SHT plays an imperative role in reducing saturated fatty acid (SFA), increasing unsaturated fatty acid (USFA), and keeping a higher unsaturation level in peach fruit. Meanwhile, SHT enhanced the activity of fatty acid synthetase (FAS), upregulated the expression levels of FAD2, FAD3-1, FAD3-2, and FAD7 genes at the early stage of storage, as well as inhibited the activity of lipoxygenase (LOX) and gene expression of LOX1. These results suggested that SHT could increase fatty acids unsaturation by regulating FAS activity, FAD and LOX1 gene expression, thus maintain high membrane stability and alleviate CI. PRACTICAL APPLICATIONS: CI is an important factor affecting the postharvest quality of peaches in cold storage, and metabolism of membrane fatty acids is one of the main CI response mechanisms. Our previous study has shown that SHT could alleviate CI in peach fruit. Therefore, it is of great significance to investigate the regulation of membrane fatty acids metabolism under SHT. Results from this study suggest that the enhancement of chilling tolerance by SHT in peaches could be explained, at least in part, as being due to enhanced FAS activity, upregulated the expression of FAD gene, and inhibited LOX1 to maintain higher unsaturation level. All in all, we explored the response mechanism of membrane fatty acids metabolism under SHT in peach fruit, and supplied theoretical guidance for application of the technology.

Combination of sodium alginate and nitric oxide reduces browning and retains the quality of fresh-cut peach during cold storage.

Fresh-cut peaches are susceptible to browning when exposed to air. Reducing the browning is important to maintain the quality of the fresh-cut peaches. Nitric oxide (NO) as the signal factor can improve the antioxidant capacity of organisms; sodium alginate (SA) is a natural polysaccharide with good antibacterial and film-forming properties. The study aimed to investigate the antioxidant and anti-browning activities of combined application of sodium alginate and nitric oxide on peaches slices preservation. The activities of some browning-related enzymes and antioxidant enzymes and the content of reactive oxygen species (ROS) and some browning-related components in fresh-cut peaches were determined. Results showed that combined treatment of 1% SA + 10 µmol/L NO slowed down the decrease in firmness, L*, and SSC, restrained the increase in browning degree and the activities of polyphenol oxidase, phenylalanine ammonia-lyase, peroxidase, and lipoxygenase. At the same time, it reduced the accumulation of O2•-, ·OH, H2O2, malondialdehyde, and total phenolic, and increased the activities of catalase and superoxide dismutase in peach slices. Overall, it was concluded that treatment with 1% SA + 10 µmol/L NO maintained quality and extended storage life of fresh-cut peaches.