Sodium para-aminosalicylate delays pericarp browning of litchi fruit by inhibiting ROS-mediated senescence during postharvest storage

Tert-Butylhydroquinone retards longan fruit deterioration by regulating membrane lipid and energy metabolisms

Longan fruit deteriorates rapidly after harvest, which limits its storability. This study aimed to investigate the effect of tert-butylhydroquinone (TBHQ) on quality maintenance, membrane lipid metabolism, and energy status of longan fruit during 25 °C storage. Compared with control fruit, TBHQ treatment maintained better marketable fruit rate and suppressed activities of phospholipase D (PLD), lipase, and lipoxygenase (LOX), and downregulated expressions of DlPLD, DlLOX, and Dllipase. TBHQ also increased the ratio of unsaturated fatty acids to saturated fatty acids (U/S) and the index of unsaturated fatty acids (IUFA). In addition, higher levels of ATP, ADP, energy charge, NADP+/ NADPH as well as higher activities of H+-ATPase, Ca2+-ATPase and NADK were also observed in TBHQ-treated fruit. These results suggested that TBHQ may maintain postharvest quality of longan fruit by regulating membrane lipid and energy metabolisms.

Prolong the shelf-life of the Pakchoi seedlings through the ammonium glycyrrhizinate

Pakchoi seedlings (Brassica chinensis L.) is susceptible to damage and spoilage during harvest and transport, leading to significant quality deterioration and financial losses. This study explored the use of ammonium glycyrrhizinate (AG) to address these issues. AG self-assembles into macromolecules at room temperature, blocking stomata and regulating respiration rates in Pakchoi seedlings. Additionally, it disrupts bacterial cell biofilm and inhibits its synthesis. While AG has been used in medicine, its application in the food industry remains limited. The study found that incorporating AG in Pakchoi seedlings preserves water content and total soluble solids (TSS), while preventing declines in catalase (CAT), Vitamin C (VC), and chlorophyll during storage. AG also reduced malondialdehyde (MDA) levels and maintained peroxidase (POD) and superoxide dismutase (SOD) activities. At a concentration of 4.25 g L-1, AG enhanced radical scavenging ability and extended the shelf life of Pakchoi seedlings by inhibiting bacteria and postponing senescence.

tert-Butylhydroquinone alleviates a postharvest pericarp browning of longan fruit by regulating antioxidant metabolism

Harvested longan fruit is prone to pericarp browning, which restricts preservation quality and shortens fruit shelf life. The antioxidant system can defend against oxidative stress-mediated quality deterioration such as fruit browning. This study aimed to evaluate the effect of tert-butylhydroquinone (TBHQ) on anti-browning ability of longan fruit in association with redox metabolism. The results indicated that the application of 0.02% TBHQ significantly suppressed the progression of pericarp browning. In comparison with control, TBHQ treatment decreased the contents of hydrogen peroxide (H2O2), superoxide radical (O2 -⋅), and malondialdehyde, and retained high levels of ascorbic acid (AsA), glutathione (GSH), total phenolics as well as 1,1-diphenyl-2-picrylhydrazyl scavenging rate. Enhanced enzymatic activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase, and dehydroascorbate reductase (DHAR), but decreased activities of polyphenol oxidase and peroxidase were also observed in TBHQ-treated fruit. Gene expression analysis indicated that redox metabolism-related genes, including DlSOD, DlCAT, DlGR, and DlAPX, were upregulated after TBHQ treatment. Correlation analysis suggested that antioxidants, including AsA, GSH, CAT, APX, SOD, and DHAR, were negatively correlated to reactive oxygen species production and percarp browning. These results suggest that TBHQ is effective in alleviating pericarp browning by increasing antioxidant capacity of longan fruit.

Hydrogen sulfide alleviates pericarp browning in lichi fruit by modulating energy and sugar metabolisms

Postharvest litchi is susceptible to browning that limits the development of litchi industry. Hydrogen sulfide (H2S) is an important bioactive molecule that can regulate many physiological processes. This study examined the effects of exogenous H2S on pericarp browning and related physiological mechanisms in postharvest litchi. The results exhibited that exogenous H2S treatment delayed the browning of litchi pericarp and reduced the damage to cell membrane integrity during storage. This treatment inhibited the energy losses of litchi fruit by increasing the activities of H+-ATPase, Ca2+- ATPase, cytochrome C oxidase (CCO) and succinate dehydrogenase (SDH) and regulating the expression of energy metabolism-related genes, including LcAtpB, LcSnRK2, LcAAC1, LcAOX1 and LcUCP1. In addition, H2S treatment increased the levels of fructose, glucose, sucrose, inositol, galactose and sorbose in litchi fruit, and promoted sucrose synthesis by regulating the activities of sucrose phosphate synthase (SPS), sucrose synthase (SS), acid invertase (AI) and neutral invertase (NI). Based on the current findings, we suggest that exogenous H2S enhances the energy supply and antioxidant activity of litchi by modulating energy and sugar metabolism, thereby inhibiting fruit browning and senescence. These results indicated that H2S treatment is an effective approach to maintaining the quality of litchi fruit and extending its shelf life.

Metabolomics comparison of four varieties apple with different browning characters in response to pretreatment during pulp processing

Browning commonly appeared in apple processing, which varied in different apple varieties. Present work investigated the metabolomics of four varieties apple of Yataka, Gala, Sansa, and Fuji, which possessed different browning characteristics and related enzymes. Sansa as browning insensitive apple variety, exhibited the least chroma change with the lowest PPO activity and the highest SOD activity among the four apple varieties. Browning inhibition pretreatment increased the activity of SOD and PAL and decreased PPO and POD activity. In addition, metabolomic variances among the four apple varieties (FC), their browning pulp (BR) and browning inhibition pulp (CM) were compared. And the key metabolites were in-depth analyzed to match the relevant KEGG pathways and speculated metabolic networks. There were 487, 644, and 494 significant differential metabolites detected in FC, BR and CM, which were consisted of lipids, benzenoids, phenylpropanoids, organheterocyclic compounds, organic acids, nucleosides, accounting for 23 %, 11 %, 15 %, 16 %, 11 % of the total metabolites. The differential metabolites were matched with 39, 49, and 36 KEGG pathways in FC, BR, and CM, respectively, in which other secondary metabolites biosynthesis metabolism was the most significant in FC, lipid metabolism was the most significant in BR and CM, and energy metabolism was markedly annotated in CM. Notably, Sansa displayed the highest number of differential metabolites in both its BR (484) and CM (342). The BR of Sansa was characterized by flavonoid biosynthesis, while the other three apple varieties were associated with α-linolenic acid metabolism. Furthermore, in browning sensitive apple varieties, the flavonoid and phenylpropanoid biosynthesis pathway was significantly activated by browning inhibition pretreatment. Phenolic compounds, lipids, sugars, organic acids, nucleotides, and adenosine were regulated differently in the four apple varieties, potentially serving as key regulatory sites. Overall, this work provides novel insight for browning prevention in different apple varieties.

Mechanisms of Litchi Response to Postharvest Energy Deficiency via Energy and Sugar Metabolisms

In the post-harvest phase, fruit is inexorably subjected to extrinsic stressors that expedite energy expenditure and truncate the storage lifespan. The present study endeavors to elucidate the response strategies of litchi to the alterations of energy state caused by 2,4-Dinitrophenol (DNP) treatment through energy metabolism and sugar metabolism. It was observed that the DNP treatment reduced the energy state of the fruit, exacerbated membrane damage and triggered rapid browning in the pericarp after 24 h of storage. Furthermore, the expression of genes germane to energy metabolism (LcAtpB, LcAOX1, LcUCP1, LcAAC1, and, LcSnRK2) reached their peak within the initial 24 h of storage, accompanied by an elevation in the respiratory rate, which effectively suppressed the rise in browning index of litchi pericarp. The study also posits that, to cope with the decrease of energy levels and membrane damage, litchi may augment the concentrations of fructose, glucose, inositol, galactose, and sorbose, thus safeguarding the canonical metabolic functions of the fruit. Collectively, these findings suggest that litchi can modulate energy and sugar metabolism to cope with fruit senescence under conditions of energy deficiency. This study significantly advances the understanding of the physiological responses exhibited by litchi fruit to post-harvest external stressors.

Dynamic interplay of reactive oxygen and nitrogen species (ROS and RNS) in plant resilience: unveiling the signaling pathways and metabolic responses to biotic and abiotic stresses

KEY MESSAGE

Plants respond to environmental challenges by producing reactive species such as ROS and RNS, which play critical roles in signaling pathways that lead to adaptation and survival strategies. Understanding these pathways, as well as their detection methods and effects on plant development and metabolism, provides insight into increasing crop tolerance to combined stresses. Plants encounter various environmental stresses (abiotic and biotic) that affect plant growth and development. Plants sense biotic and abiotic stresses by producing different molecules, including reactive species, that act as signaling molecules and stimulate secondary messengers and subsequent gene transcription. Reactive oxygen and nitrogen species (ROS and RNS) are produced in both physiological and pathological conditions in the plasma membranes, chloroplasts, mitochondria, and endoplasmic reticulum. Various techniques, including spectroscopy, chromatography, and fluorescence methods, are used to detect highly reactive, short-half-life ROS and RNS either directly or indirectly. In this review, we highlight the roles of ROS and RNS in seed germination, root development, senescence, mineral nutrition, and post-harvest control. In addition, we provide information on the specialized metabolism involved in plant growth and development. Secondary metabolites, including alkaloids, flavonoids, and terpenoids, are produced in low concentrations in plants for signaling and metabolism. Strategies for improving crop performance under combined drought and pathogen stress conditions are discussed in this review.

Skeletal muscle mitochondrial dysfunction mediated by Pseudomonas aeruginosa quorum-sensing transcription factor MvfR: reversing effects with anti-MvfR and mitochondrial-targeted compounds

Sepsis and chronic infections with Pseudomonas aeruginosa, a leading "ESKAPE" bacterial pathogen, are associated with increased morbidity and mortality and skeletal muscle atrophy. The actions of this pathogen on skeletal muscle remain poorly understood. In skeletal muscle, mitochondria serve as a crucial energy source, which may be perturbed by infection. Here, using the well-established backburn and infection model of murine P. aeruginosa infection, we deciphered the systemic impact of the quorum-sensing transcription factor MvfR (multiple virulence factor regulator) by interrogating, 5 days post-infection, its effect on mitochondrial-related functions in the gastrocnemius skeletal muscle and the outcome of the pharmacological inhibition of MvfR function and that of the mitochondrial-targeted peptide, Szeto-Schiller 31 (SS-31). Our findings show that the MvfR perturbs adenosine triphosphate generation, oxidative phosphorylation, and antioxidant response, elevates the production of reactive oxygen species, and promotes oxidative damage of mitochondrial DNA in the gastrocnemius muscle of infected mice. These impairments in mitochondrial-related functions were corroborated by the alteration of key mitochondrial proteins involved in electron transport, mitochondrial biogenesis, dynamics and quality control, and mitochondrial uncoupling. Pharmacological inhibition of MvfR using the potent anti-MvfR lead, D88, we developed, or the mitochondrial-targeted peptide SS-31 rescued the MvfR-mediated alterations observed in mice infected with the wild-type strain PA14. Our study provides insights into the actions of MvfR in orchestrating mitochondrial dysfunction in the skeletal murine muscle, and it presents novel therapeutic approaches for optimizing clinical outcomes in affected patients.

IMPORTANCE

Skeletal muscle, pivotal for many functions in the human body, including breathing and protecting internal organs, contains abundant mitochondria essential for maintaining cellular homeostasis during infection. The effect of Pseudomonas aeruginosa (PA) infections on skeletal muscle remains poorly understood. Our study delves into the role of a central quorum-sensing transcription factor, multiple virulence factor regulator (MvfR), that controls the expression of multiple acute and chronic virulence functions that contribute to the pathogenicity of PA. The significance of our study lies in the role of MvfR in the metabolic perturbances linked to mitochondrial functions in skeletal muscle and the effectiveness of the novel MvfR inhibitor and the mitochondrial-targeted peptide SS-31 in alleviating the mitochondrial disturbances caused by PA in skeletal muscle. Inhibiting MvfR or interfering with its effects can be a potential therapeutic strategy to curb PA virulence.

Integrated bioinformatics and validation reveal PTGS2 and its related molecules to alleviate TNF-α-induced endothelial senescence

Accumulative evidences have indicated the interaction between cellular senescence and ferroptosis. This study intends to investigate the ferroptosis-related molecular markers in TNF-α-induced endothelial senescence. The microarray expression dataset (GSE195517) was used to identify the differently expressed ferroptosis-related genes (DEFRGs) through weighted gene co-expressed network analysis (WGCNA). GO and KEGG were performed to explore the biological function. Furthermore, hub genes were identified after protein-protein interaction (PPI) analysis and validated through real-time qPCR (RT-qPCR). Then, a drug-gene network was established to predict potential drugs for the hub genes. Seven DEFRGs were recognized in the TNF-α-induced HUVEC senescence. Moreover, four hub genes (PTGS2, TNFAIP3, CXCL2, and IL6 are upregulated) were identified by PPI analysis and validated by RT-qPCR. Further analysis exhibited that PTGS2 was subcellularly located in the plasma membrane. Furthermore, after aminosalicylic acid (ASA) was identified as ferroptosis inhibitor for targeting PTGS2 in senescent HUVECs, 5-ASA and 4-ASA were verified to alleviate TNF-α-induced HUVEC senescence through ferroptosis. PTGS2 might play a role in TNF-α-induced HUVEC senescence and ASA may be the potential drug for alleviating TNF-α-induced HUVEC senescence through ferroptosis.

l-Arginine treatment maintains postharvest quality in blueberry fruit by enhancing antioxidant capacity during storage

The postharvest quality of blueberry fruit is largely limited by deterioration. l-arginine (Arg) is a functional nontoxic amino acid with high biological activities. This study investigated the positive effects and the underlying mechanism of Arg treatment on the quality of postharvest blueberries. Arg effectively mitigated fruit decay and improved the quality of blueberries, including weight loss, firmness, and soluble solid content. Mechanistically, Arg-mediated activation of the anti-oxidative defense system reduced reactive oxygen species-mediated oxidative damage. Moreover, Arg treatment decreased the activities and gene expression of phospholipase D, lipoxygenase, and lipase-inhibiting membrane lipid peroxidation during the prolonged storage of blueberries. Meanwhile, Arg treatment increased nitric oxide (NO) content and NO synthase activity. Furthermore, correlation and principal component analyses revealed the enhancement of Arg treatment on antioxidant capacity. This study suggests that Arg treatment can maintain the postharvest quality of blueberries by improving antioxidant capacity.

Exogenous glutathione maintains the postharvest quality of mango fruit by modulating the ascorbate-glutathione cycle

Background

Mango fruit is prone to decay after harvest and premature senescence, which significantly lowers its quality and commercial value.

Methods

The mango fruit (Mangifera indica L.cv. Guixiang) was treated with 0 (control), 2, 5, and 8 mM of reduced glutathione (GSH) after harvest. The fruit was stored at 25 ± 1 °C for 12 days to observe the changes in the antioxidant capacity and postharvest quality.

Results

Compared with the control, the 5 mM GSH treatment significantly decreased the weight loss by 44.0% and 24.4%, total soluble solids content by 25.1% and 4.5%, and soluble sugar content by 19.0% and 27.0%. Conversely, the 5 mM GSH treatment increased the firmness by 25.9% and 30.7% on days 4 and 8, respectively, and the titratable acidity content by 115.1% on day 8. Additionally, the 5 mM GSH treatment decreased the malondialdehyde and hydrogen peroxide contents and improved the antioxidant capacity of mango fruit by increasing the superoxide dismutase and peroxidase activities and upregulating the expression of the encoding genes. Meanwhile, the higher levels of monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase enzyme activities and gene expressions accelerated the AsA-GSH cycle, thereby increasing the accumulation of AsA and GSH and maintaining the redox balance.

Conclusions

Overall, the experimental results suggest that 5 mM GSH maintains high antioxidant capacity and postharvest quality of mangoes and can use as an effective preservation technique for postharvest mangoes.

Vishniacozyma victoriae: An endophytic antagonist yeast of kiwifruit with biocontrol effect to Botrytis cinerea

Botrytis cinerea is a pathogenic fungus to fruit, biocontrol is a promising approach to relieve this issue. In this study, Vishniacozyma victoriae is an endophytic yeast extracted from kiwifruit, was used to enhance the resistance of host to B. cinerea. The results showed that lesion diameter of the kiwifruit inoculated with B. cinerea was 55.16 %, 50.57 %, and 48.07 % lower than that of inoculated with V. victoriae + B. cinerea on 4th, 8th, and 12th day, respectively. On 12th day, the total organic acid content and energy charge of kiwifruit inoculated with B. cinerea were 19.25 % and 7.95 % lower than those inoculated with V. victoriae + B. cinerea. These indicated that V. victoriae used the organic acids and energy of host to colonize in the wound, which prevented B. cinerea from contacting the host. Accordingly, V. victoriae is a promising biocontrol yeast to inhibit the infection of B. cinerea on kiwifruit.

Effects of Growth Period and Storage Methods on Primary Metabolite Contents and Antioxidant Activities of Morus alba L. Leaf

(1) Background: Mulberry leaves have been widely consumed due to their richness in bioactive substances and high antioxidant activity. The choice of storage method to ensure the quality of mulberry leaves is a challenge in the supply process. (2) Methods: The differences in primary metabolites of freeze-dried mulberry leaf powder after 30 days of storage under different storage conditions (i.e., vacuum or non-vacuum, 4 °C or room temperature) were investigated. (3) Results: A low temperature and vacuum had better preservation effects on the types and activity of the primary metabolites of mulberry leaves, with vacuum preservation being the best. However, the types of primary metabolites in mulberry leaves were significantly reduced after non-vacuum storage at room temperature compared to those with other storage methods. Among the metabolites detected, including dehydroascorbic acid, various phenolic acids, amino acids, lipids, and carbohydrates showed a significant decrease in their contents of more than 40%, and there was a significant increase in the contents of various compounds of the muconic acid biosynthetic pathway compared to those in other storage methods. Moreover, the antioxidant activity of mulberry leaves stored at room temperature under non-vacuum conditions was also significantly reduced. (4) Conclusions: Vacuum storage is the most ideal storage method for preserving mulberry leaves.

OsSCL30 overexpression reduces the tolerance of rice seedlings to low temperature, drought and salt

Rice is one of the main food crops for the world population. Various abiotic stresses, such as low temperature, drought, and high salinity, affect rice during the entire growth period, determining its yield and quality, and even leading to plant death. In this study, by constructing overexpression vectors D-163 + 1300:OsSCL30 and D-163 + 1300-AcGFP:OsSCL30-GFP, the mechanism of action of OsSCL30 in various abiotic stresses was explored. Bioinformatics analysis showed that OsSCL30 was located on the chromosome 12 of rice Nipponbare, belonging to the plant-specific SCL subfamily of the SR protein family. The 1500 bp section upstream of the open reading frame start site contains stress-related cis-acting elements such as ABRE, MYC, and MYB. Under normal conditions, the expression of OsSCL30 was higher in leaves and leaf sheaths. The results of reverse transcription polymerase chain reaction showed that the expression of OsSCL30 decreased after low temperature, drought and salt treatment. In root cells OsSCL30 was localized in the nuclei. The results of the rice seedling tolerance and recovery tests showed that overexpression of OsSCL30 diminished the resistance to low temperature, drought and salt stresses in transgenic rice and resulted in larger accumulation of reactive oxygen species. This study is of great significance for exploring the response mechanisms of SR proteins under abiotic stresses.

Propyl Gallate Treatment Improves the Postharvest Quality of Winter Jujube (Zizyphus jujuba Mill. cv. Dongzao) by Regulating Antioxidant Metabolism and Maintaining the Structure of Peel

The quality and color of winter jujube fruits are easy to change after harvest. We studied the regulation mechanism of propyl gallate (PG) on post-harvest physiological quality of winter jujube, from the perspective of antioxidant metabolism and peel structure. In our research, winter jujube fruits were treated with 0.001 mol L⁻¹ PG solution for 20 min. Our results showed that PG delayed the development of peel color, and improved the firmness, total soluble solids (TSS), and titratable acid (TA) of winter jujube. Meanwhile, the PG treatment had higher content of total phenols, total flavonoids, ascorbic acid (AsA), and reduced glutathione (GSH), and kept the enzyme activity including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD) at a higher level. PG treatment reduced membrane oxidative damage and maintained the integrity of pericarp structure by reducing electrolyte leakage (EL), lipoxygenase activity (LOX), hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) content in the peel. Accordingly, PG improved the postharvest quality of jujube fruits by regulating antioxidant metabolism and maintaining the structure of peel. The appropriate concentration of PG has good application potential in the storage and preservation of fresh fruits such as winter jujube.

Fumonisin B1 induced aggressiveness and infection mechanism of Fusarium proliferatum on banana fruit

Mycotoxins are increasingly considered as micropollutants in the environment. Fumonisins, as one of the most important mycotoxins, cause potential health threats to humans and animals due to their ubiquitous contamination on cereals, fruit, vegetables and other environmental samples around the world. However, the contribution of fumonisins to the interaction of fungi with plant hosts is not still fully understood. Here, we investigated the effect of fumonisin B1 (FB1) on the infection of Fusarium proliferatum on banana fruit and the underlying mechanisms from the host perspective. Our results found that FB1 treatment increased the aggressiveness of F. proliferatum on banana fruit and inhibited the defense ability of banana fruit via decreasing phenylalanine ammonia lyase (PAL), β-1,3-glucanase (GLU) and chitinase (CHI) activities. Meanwhile, FB1 accelerated cell death, indicated by higher relative conductivity, MDA content and higher transcripts of cell death-related genes. FB1 treatment resulted in higher hydrogen peroxide (H₂O₂) content possibly due to MaRBOHs induction. These consequences accelerated the ROS-dependent cell death, which subsequently result in reduction of disease resistance of banana fruit. Additionally, energy metabolism and MaDORN1s-mediated eATP signaling might involve in FB1-meidiated suppression of banana defense responses. Collectively, results of the current study indicated that FB1 contamination triggered the cell death of banana peel, subsequently instigating the invasion and growth of F. proliferatum on banana fruit. In summary, for the first time, we demonstrated a previously unidentified role of fumonisins as a potential virulence factor of F. proliferatum in modulating fruit defense response, which provides new insight on the biological roles of fumonisins.

Benzothiazole Treatment Regulates the Reactive Oxygen Species Metabolism and Phenylpropanoid Pathway of Rosa roxburghii Fruit to Delay Senescence During Low Temperature Storage

Rosa roxburghii fruit were used as research objects to study the effects of different concentrations of benzothiazole (BTH) treatment on quality parameters, reactive oxygen species (ROS) metabolism, and the phenylpropanoid pathway during storage at 4°C for 14days. Results showed that BTH effectively delayed senescence with lower decay incidence, weight loss, and lipid peroxidation level and maintained the quality with higher contents of total soluble solid (TSS) content, titratable acidity (TA) in R. roxburghii fruit. Moreover, BTH increased hydrogen peroxide (H₂O₂) content, superoxide anion (O₂ ^•-) production rate, and the activities and expression of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione (GSH) reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and peroxidase (POD), and the contents of GSH and ascorbic acid (AsA), but reduced the oxidized GSH (GSSG) content. In addition, the activities and gene expression of phenylalanine ammonia lyase (PAL), cinnamate 4-hydroxylase (C4H), and 4-coumarate-CoA ligase (4CL) and the concentrations of flavonoids, total phenols, and lignin were significantly elevated by BTH. These findings imply that BTH can delay senescence and maintain the quality of R. roxburghii fruit by modulating ROS metabolism and the phenylpropanoid pathway under low-temperature conditions.

Litchi (Litchi chinensis Sonn.): a comprehensive review of phytochemistry, medicinal properties, and product development

Since ancient times, litchi has been well recognized as a functional food for the management of various ailments. Many bioactives, including flavanoids, anthocyanins, phenolics, sesquiterpenes, triterpenes, and lignans, have been identified from litchi with a myriad of biological properties both in vitro and in vivo. In spite of the extensive research progress, systemic reviews regarding the bioactives of litchi are rather scarce. Therefore, it is crucial to comprehensively analyze the pharmacological activities and the structure-activity relationships of the abundant bioactives of litchi. Besides, more and more studies have focused on litchi preservation and development of its by-products, which is significant for enhancing the economic value of litchi. Based on the analysis of published articles and patents, this review aims to reveal the development trends of litchi in the healthcare field by providing a systematic summary of the pharmacological activities of its extracts, its phytochemical composition, and the nutritional and potential health benefits of litchi seed, pulp and pericarp with structure-activity relationship analysis. In addition, its by-products also exhibited promising development potential in the field of material science and environmental protection. Furthermore, this study also provides an overview of the strategies of the postharvest storage and processing of litchi.

Chilling injury mechanism of hardy kiwifruit (Actinidia arguta) was revealed by proteome of label-free techniques

Refrigeration is an important method to extend shelf life of hardy kiwifruit. However, the inappropriate storage temperature can lead to chilling injury in the fruit. We found that firmness, total soluble solids, and total polyphenolic content of the fruit exposed to 0℃ environment were apparently lower, and titratable acidity content, browning rate, weight loss rate, electrolyte leakage, proline content, and malondialdehyde content were higher obviously than 4℃. A total of 244 differentially expressed proteins were found result from differential temperatures, among which 113 were up-regulated and 131 were down-regulated. Subcellular localization results presented that the differentially expressed proteins which were affected by low temperature were located in cytoplasmic, chloroplast, nuclear, mitochondrial, plasma membrane, and extracellular. Kyoto Encyclopedia of Genes and Genomes analysis showed that the differentially expressed proteins were mainly participated in synthesis of citrate cycle, oxidative phosphorylation, fatty acid biosynthesis, and starch and sucrose metabolism. Protein-protein interaction results revealed that central proteins interaction points respectively are 30S ribosomal proteins, 30S ribosomal protein S7, chloroplastic, cell division cycle 5-like protein, 50S ribosomal protein, ribosomal protein, ribosomal protein L6 protein, and SRP54 subunit protein. The quality deviations of all identified peptides were mainly distributed within 10 ppm, and MS2 has an ideal andromeda score, with more than 87.82% peptide scores above 60 points, and the median peptide score of 99.28 points. Therefore, the results of this study provide important information for new gene revelation and gene interaction relationship in hardy kiwifruit of chilling injury. PRACTICAL APPLICATIONS: Inhibition of cold damage in hardy kiwifruit under low temperature is very important work for the development of its storage industry. However, many qualities of fruit will deteriorate after long-term cold storage and those biological activities of the fruits are regulated by proteins. It is, therefore, of great significance to reveal the key proteins caused cold damage in hardy kiwifruit. Moreover, the study results could provide a scientific information for the quality improvement and genetic modification of hardy kiwifruit.

Study on browning mechanism of fresh-cut eggplant (Solanum melongena L.) based on metabolomics, enzymatic assays and gene expression

Enzymatic browning is one of the crucial problems compromising the flavor and texture of fresh-cut fruit and vegetables. In this study, an untargeted metabolomics approach based on liquid chromatography-mass spectrometry (LC-MS) was used to explore the browning mechanism in fresh-cut eggplant. Metabolomics studies showed that with the increase of fresh-cut time, the contents of 946 metabolites changed dynamically. The metabolites having the same trend share common metabolic pathways. As an important browning substrate, the content of chlorogenic acid increased significantly, suggesting that may be more important to fresh-cut eggplant browning; all 119 common differential metabolites in 5 min/CK and 3 min/CK contrastive groups were mapped onto 31 KEGG pathways including phenylpropanol metabolism, glutathione metabolism pathway, et al. In physiological experiments, results showed that the Phenylpropanoid-Metabolism-Related enzymes (PAL, C4H, 4CL) were changed after fresh-cut treatment, the activities of three enzymes increased first and then decreased, and reached the maximum value at 5 min, indicating the accumulation of phenolic substances. At the same time, ROS were accumulated when plant tissue damaged by cutting, the activities of related antioxidant enzymes (SOD, APX and CAT) changed dynamically after oxidative damage. SOD and APX content increased significantly and reached the maximum value at 10 min after cutting, and then showed a downward trend. However, CAT activity increased sharply and reached the maximum value within 3 min after cutting, then maintained the same activity, and showed a downward trend after 30 min. These data fully demonstrated that the activities of browning related enzymes and gene expression increased with the prolonging of fresh cutting time. We explained the browning mechanism of fresh-cut eggplant by combining metabolomics and physiology, which may lay the foundation for better understanding the mechanism of browning during the fruits and vegetables during processing.

Postharvest Aloe vera gel coating application maintains the quality of harvested green chilies during cold storage

The effect of Aloe vera (ALV) coating was studied on chillies at 10 ± 1°C for 28 days. ALV gel-coated chillies showed reduced weight loss, disease incidence, red chili percentage, respiration rate, electrolyte leakage, hydrogen peroxide, and superoxide anion contents. The ALV coating maintained general acceptance in terms of visual quality and marketability index with higher chlorophyll contents, ascorbic acid contents, total phenolic contents, and total antioxidants. In addition, ascorbate peroxidase, catalase, superoxide dismutase, and peroxidase activities were markedly higher in coated chillies compared to control. The biochemical attributes such as soluble solids content, acidity, sugar: acid ratio, and juice pH were non-significantly affected by ALV application; however, the said attributes were comparatively higher in contrast to control. In conclusion, ALV edible coating could be used as an eco-friendly approach for delaying senescence and maintaining the postharvest quality of green chillies up to 28 days. PRACTICAL APPLICATIONS: Green chilies being highly perishable exhibit limited postharvest life with rapid loss of water, shrivelling, wilting, disease incidence, and reduced consumer acceptability. ALV gel coating significantly delayed postharvest senescence, reduced disease spread, maintained higher antioxidant activities of green chilies during cold storage. Therefore, ALV coating [50%] would be the suitable alternative to synthetic preservatives for extending the storage life and conserving the quality of green chilies.

Coating shiitake mushrooms (Lentinus edodes) with a polysaccharide from Oudemansiella radicata improves product quality and flavor during postharvest storage

In this work, we investigated whether coating fresh shiitake mushrooms with a polysaccharide isolated from Oudemansiella radicata (ORWP) would impact key quality characteristics after 18 d of storage at 4 °C. We found that ORWP-coated mushrooms had significant improvements in many qualities during storage, including reduced weight loss, improved firmness, reduced browning, decreased malondialdehyde content, and an improved physical microstructure. Further, ORWP-coated mushrooms had higher contents of nutritional and cell wall compounds compared to control samples. ORWP-coated mushrooms had reduced activities of the following enzymes: protease, polyphenol oxidase, peroxidase, phenylalanine ammonia lyase, cellulase, and chitinase, relative to control samples. However, mushrooms coated with ORWP had higher concentrations of superoxide dismutase and catalase, as well as higher contents of certain key monosodium glutamate-resembling amino acids, umami 5'-nucleotides and 1-octen-3-ol. These findings suggest that ORWP coatings have potential value as a method to improve the postharvest quality of shiitake mushrooms.

Sodium Nitroprusside Functions in Browning Control and Quality Maintaining of Postharvest Rambutan Fruit

Surface browning after harvest is the primary constraint affecting the storage life and market circulation of rambutans. In this study, rambutan fruits were soaked in sodium nitroprusside at different concentrations and stored at 25°C for 8 days to explore the effects on postharvest quality and browning. The weight loss, browning index and superoxide anion radical, hydrogen peroxide and malondialdehyde contents of the treated fruits were reduced compared to those of the control fruits (soaked in distilled water). And fruits treated with sodium nitroprusside had a higher total phenolic content and lower polyphenol oxidase and peroxidase activity. In addition, compared with the control, the treated fruits exhibited higher phenylalanine ammonia lyase, ascorbate peroxidase and superoxide dismutase activities; titratable acidity; and soluble solid, vitamin C and protein contents, indicating high fruit quality. Overall, sodium nitroprusside treatment at 200 μmol L^-1 demonstrated the most positive preservation effects. Therefore, sodium nitroprusside treatment, particularly at 200 μmol L^-1, can be used as an eco-friendly, safe and convenient method for postharvest quality management and high-efficiency preservation of rambutan fruits.

Reactive Oxygen Species and Antioxidants in Postharvest Vegetables and Fruits

Reducing oxidative species to non- or less-reactive matter is the principal function of an antioxidant. Plant-based food is the main external source of antioxidants that helps protect our cells from oxidative damage. During postharvest storage and distribution, fruits and vegetables often increase ROS production that is quenched by depleting their antioxidant pools to protect their cells, which may leave none for humans. ROS are molecules produced from oxygen metabolism; some of the most widely analyzed ROS in plants are singlet oxygen, superoxide, hydrogen peroxide, and hydroxyl radicals. ROS concentration and lifetime are determined by the availability and composition of the antioxidant system that includes enzymatic components such as SOD, CAT, and APX and nonenzymatic components such as vitamins, polyphenols, and carotenoid. Depending on its concentration in the cell, ROS can either be harmful or beneficial. At high concentrations, ROS can damage various kinds of biomolecules such as lipids, proteins, DNA, and RNA, whereas at low or moderate concentrations, ROS can act as second messengers in the intracellular signaling cascade that mediates various plant responses. Novel postharvest methods are sought to maintain fruit and vegetable quality, including minimizing ROS while preserving their antioxidant content.

Combination of liquid-phase pulsed discharge and ultrasonic for saponins extraction from lychee seeds

A skillfully combined method of liquid-phase pulsed discharge and ultrasonic (LPDU) had been developed for saponins extraction from lychee seeds. Single factor and response surface methods were used to optimize the system, respectively. The optimized conditions included 30% aqueous ethanol, 62.66 mL/g ratio of liquid to solid, 3 mm centre hole diameter of hollow electrode, 123 mL/min flow velocity, length of serpentine pipe of 15 cm, 276 W ultrasonic power, 47 °C ultrasonic temperature, and discharge voltage was fixed at 14 kV. Under these conditions, it obtained a maximum saponins yield of 51.30 ± 0.08 mg/g with 10 min, which was higher than those of LPD (42.33 ± 0.98 mg/g) with 24 min, ultrasonic assisted extraction (UAE) (41.80 ± 1.31 mg/g) with 30 min and maceration (38.72 ± 1.13 mg/g) with 180 min. Meanwhile, the energy consumption of LPDU was 7560 kJ/kg, which was notably lower than those of LPD (8820 kJ/kg), UAE (25875 kJ/kg) and maceration (10248 kJ/kg). We found that the saponin constituents of LPDU were similar to LPD, UAE, ME by HPLC content detection method, and found that LPDU had the highest degree of tissue damage after scanning electron microscope (SEM) comparison, which verified the reason for its high extraction efficiency. The results showed that LPDU was an effective technology for saponins extraction, which may be potentially applied in cosmetics, medicines and food chemistry.

Effects of hydrogen water treatment on antioxidant system of litchi fruit during the pericarp browning

Litchi fruit were exposed to 0.7 PPM hydrogen water (HW) before storage at 25 ± 1 ℃. HW treatment delayed the pericarp browning and maintained the total soluble solids (TSS) of litchi fruit. Then, a total of 25 antioxidant system-related characters were determined to evaluate the effects of HW on antioxidant system during pericarp browning. Compared with control pericarp, the pericarp of HW-treated litchi fruit exhibited higher levels of superoxide radical (O_2^-·) scavenging activity, glutathione (GSH), monodehydroascorbate reductase (MDHAR), polyphenol oxidase (PPO) and total flavonoids during whole storage, higher levels of hydrogen peroxide (H₂O₂), catalase (CAT), glutathione disulfide (GSSG), ascorbate oxidase (AAO) and total phenols only on day 1, and higher levels of ascorbate peroxidase (APX), total anthocyanin, glutathione reductase (GR) and glutathione peroxidases (GPX) at later stage of storage. Those HW-induced antioxidant system-related characters might directly or indirectly enhanced the antioxidant capacity and delayed the pericarp browning of litchi.

Postharvest Application of Acibenzolar-S-methyl Delays the Senescence of Pear Fruit by Regulating Reactive Oxygen Species and Fatty Acid Metabolism

This study investigated the changes in enzyme activity and gene expression in reactive oxygen species (ROS) and fatty acid metabolism in Docteur Jules Guyot pears after acibenzolar-S-methyl (ASM) treatment to elucidate the role of ROS and fatty acid metabolism in senescence. The results demonstrated that applying ASM postharvest significantly suppressed H₂O₂ content and enhanced catalase and superoxide dismutase activities in pears. Ascorbate peroxidase, glutathione reductase, dehydroascorbate reductase, and monodehydroascorbate reductase activities and the reduced glutathione content in pears were also induced by ASM. Postharvest ASM dipping remarkably enhanced PcSOD, PcCAT, PcAPX, and PcDHAR expressions and fatty acid synthetase activity in pears. Postharvest applying ASM significantly decreased malondialdehyde content and lipoxygenase, hydroperoxidelyase, alcohol dehydrogenase, and alcohol acyltransferase activities in pears. ASM distinctly inhibited PcPLD, PcLOX, PcHPL, PcADH, and PcAAT expressions in pears. The findings suggest that postharvest applying ASM could modulate ROS and fatty acid metabolism to delay senescence in pears.

Chemical Defoliant Promotes Leaf Abscission by Altering ROS Metabolism and Photosynthetic Efficiency in Gossypium hirsutum

Chemical defoliation is an important part of cotton mechanical harvesting, which can effectively reduce the impurity content. Thidiazuron (TDZ) is the most used chemical defoliant on cotton. To better clarify the mechanism of TDZ promoting cotton leaf abscission, a greenhouse experiment was conducted on two cotton cultivars (CRI 12 and CRI 49) by using 100 mg L⁻¹ TDZ at the eight-true-leaf stage. Results showed that TDZ significantly promoted the formation of leaf abscission zone and leaf abscission. Although the antioxidant enzyme activities were improved, the reactive oxygen species and malondialdehyde (MDA) contents of TDZ increased significantly compared with CK (water). The photosynthesis system was destroyed as net photosynthesis (Pn), transpiration rate (Tr), and stomatal conductance (Gs) decreased dramatically by TDZ. Furthermore, comparative RNA-seq analysis of the leaves showed that all of the photosynthetic related genes were downregulated and the oxidation-reduction process participated in leaf shedding caused by TDZ. Consequently, a hypothesis involving possible cross-talk between ROS metabolism and photosynthesis jointly regulating cotton leaf abscission is proposed. Our findings not only provide important insights into leaf shedding-associated changes induced by TDZ in cotton, but also highlight the possibility that the ROS and photosynthesis may play a critical role in the organ shedding process in other crops.

Calcium maintained higher quality and enhanced resistance against chilling stress by regulating enzymes in reactive oxygen and biofilm metabolism of Chinese winter jujube fruit

The postharvest senescence of Chinese winter jujube fruit can be effectively delayed by refrigerated storage. However, chilling injury often occurs in jujube fruit during cold storage. In this study, Chinese winter jujubes were sprayed with CaCl₂ (4%) 3 times at intervals of 2 hr on the day of refrigeration. The results presented that maximum difference of 2.7 N firmness, 3.42% TAC, and 0.8 OD₂₈₀ /g polyphenol content were detected in calcium-treated fruit during cold storage, but the levels of O 2 - , MDA, hydrogen peroxide, browning rate, electrolyte leakage, and weight loss rate were significantly inhibited (p < .05). The maximum difference of enzymes activity of CAT, POD, SOD was 2.1, 10.8, and 40.6 mol h^-1 kg^-1 respectively, but 21.1 mol h^-1 kg^-1 PPO was restrained in the treated group. In conclusion, the results provided a reliable method for inhibiting cold injury and explained the internal molecular mechanism of the fruit regulated by calcium. PRACTICAL APPLICATIONS: Refrigerated storage is an important method for extending the storage time of Chinese winter jujube fruit. However, cold damage may occur when the jujubes are stored at low temperature for long-term. It is, therefore, of great significance to find a new method and reveal the molecular mechanism. We believe that our study makes a significant contribution to the literature because it provides an effective method of maintaining higher quality and mechanistic insights into the resistance against the chilling stress of jujubes.

Nanocomposite-based packaging affected the taste components of white Hypsizygus marmoreus by regulating energy status

The effects of nanocomposite-based packaging material (Nano-PM) on the taste components and mitochondrial energy metabolism of postharvest white Hypsizygus marmoreus (WHM), as well as the underlying influence mechanism were investigated. The results showed that the major taste components, including succinic acid and mannitol, remained at higher level in Nano-PM. The flavor 5'-nucleotides (5'-GMP and 5'-IMP) of WHM in Nano-PM were significantly higher (p < 0.05) compared with that in the normal packaging material (Normal-PM). Principal component analysis indicated that there was a distinction of flavor compounds (6 organic acids, 3 soluble sugars and 5 5'-nucleotides) of WHM between Nano-PM and Normal PM treatments during storage. Moreover, Nano-PM delayed the mitochondrial microstructure breakdown and the reduction of ATPase activity, and it maintained a higher ATP content and higher level of energy charge. Our results demonstrated that Nano-PM could affect the taste components of postharvest WHM partially by regulating the energy metabolism.

D‑galactose induces astrocytic aging and contributes to astrocytoma progression and chemoresistance via cellular senescence

The administration of D‑galactose triggers brain aging by poorly understood mechanisms. It is generally recognized that D‑galactose induces oxidative stress or affects protein modifications via receptors for advanced glycated end products in a variety of species. In the present study, we aimed to investigate the involvement of astrocytes in D‑galactose‑induced brain aging in vitro. We found that D‑galactose treatment significantly suppressed cell viability and induced cellular senescence. In addition, as of the accumulation of senescent cells, we proposed that the senescence‑associated secretory phenotype (SASP) can stimulate age‑related pathologies and chemoresistance in brain. Consistently, senescent astrocytic CRT cells induced by D‑galactose exhibited increases in the levels of IL‑6 and IL‑8 via NF‑κB activation, which are major SASP components and inflammatory cytokines. Conditioned medium prepared from senescent astrocytic CRT cells significantly promoted the viability of brain tumor cells (U373‑MG and N2a). Importantly, conditioned medium greatly suppressed the cytotoxicity of U373‑MG cells induced by temozolomide, and reduced the protein expression levels of neuron marker neuron‑specific class III β‑tubulin, but markedly increased the levels of c‑Myc in N2a cells. Thus, our findings demonstrated that D‑galactose treatment might mimic brain aging, and that D‑galactose could contribute to brain inflammation and tumor progression through inducing the accumulation of senescent‑secretory astrocytes.

Combination of Transcriptomic, Proteomic, and Metabolomic Analysis Reveals the Ripening Mechanism of Banana Pulp

The banana is one of the most important fruits in the world. Bananas undergo a rapid ripening process after harvest, resulting in a short shelf. In this study, the mechanism underlying pulp ripening of harvested bananas was investigated using integrated transcriptomic, proteomic, and metabolomic analysis. Ribonucleic acid sequencing (RNA-Seq) revealed that a great number of genes related to transcriptional regulation, signal transduction, cell wall modification, and secondary metabolism were up-regulated during pulp ripening. At the protein level, 84 proteins were differentially expressed during pulp ripening, most of which were associated with energy metabolism, oxidation-reduction, cell wall metabolism, and starch degradation. According to partial least squares discriminant analysis, 33 proteins were identified as potential markers for separating different ripening stages of the fruit. In addition to ethylene’s central role, auxin signal transduction might be involved in regulating pulp ripening. Moreover, secondary metabolism, energy metabolism, and the protein metabolic process also played an important role in pulp ripening. In all, this study provided a better understanding of pulp ripening of harvested bananas.

Changes in Metabolisms of Antioxidant and Cell Wall in Three Pummelo Cultivars during Postharvest Storage

The juice sacs of pummelo fruit is susceptible to softening during storage at 25 °C, which causes quality deterioration and flavor loss during postharvest pummelo storage. This study investigated the changes in metabolisms of antioxidant and cell wall in juice sacs of three pummelo cultivars—Hongroumiyou (HR), Bairoumiyou (BR) and Huangroumiyou (HuR)—during postharvest storage. The results revealed that, with the extension of storage, the juice sacs of three pummelo cultivars exhibited a decrease in total antioxidant capacity (TAC), DPPH and ABTS radical scavenging activity; a decline in total phenols (TP) content and an increase firstly then a decrease in total ascorbic acid (TAA) content; and a decrease in lipoxygenase (LOX) activity and a rise initially, but a decline in activities of ascorbate peroxidase (APX) and glutathione peroxidase (GPX). Additionally, increased water-soluble pectin (WSP), but declined propectin, ionic-soluble pectin (ISP) and chelator-soluble pectin (CSP); as well as an increase from 0 d to 60 d then followed by a decline in activities of pectinesterase (PE), polygalacturonase (PG) and pectate lyase (PL) were observed. These results suggested that the metabolisms of antioxidant and cell wall could result in softening and senescence of pummelo fruit.

Mechanism of Cell Wall Polysaccharides Modification in Harvested 'Shatangju' Mandarin (Citrus reticulate Blanco) Fruit Caused by Penicillium italicum

Modification of cell wall polysaccharide in the plant plays an important role in response to fungi infection. However, the mechanism of fungi infection on cell wall modification need further clarification. In this study, the effects of Penicillium italicum inoculation on 'shatangju' mandarin disease development and the potential mechanism of cell wall polysaccharides modification caused by P. italicum were investigated. Compared to the control fruit, P. italicum infection modified the cell wall polysaccharides, indicated by water-soluble pectin (WSP), acid-soluble pectin (ASP), hemicellulose and lignin contents change. P. italicum infection enhanced the activities of polygalacturonase (PG), pectin methylesterase (PME), and the expression levels of xyloglucanendotransglucosylase/hydrolase (XTH) and expansin, which might contribute to cell wall disassembly and cellular integrity damage. Additionally, higher accumulation of reactive oxygen species (ROS) via decreasing antioxidant metabolites and the activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) also contributed to the cell wall polysaccharides modification. Meanwhile, the gene expression levels of hydroxyproline-rich glycoprotein (HRGP) and germin-like protein (GLP) were inhibited by pathogen infection. Altogether, these findings suggested that cell wall degradation/modification caused by non-enzymatic and enzymatic factors was an important strategy for P. italicum to infect 'shatangju' mandarin.

Changes in pericarp metabolite profiling of four litchi cultivars during browning

The pericarp browning is an important physiological index during the postharvest storage, which seriously shortens the shelf-life of litchi fruit. In this study, the browning index of four litchi cultivars were compared, and the shelf-life, from longer to shorter, was 'Feizixiao (FXZ)', 'Jingganghongnuo (JGHN)', 'Huaizhi (HZ)' and 'Nuomici (NMC)', respectively. Then, comparative metabolomics were performed in the pericarp of four litchi cultivars during browning. Finding results showed that a total of 119 kinds of metabolites were detected in litchi pericarp, including 30 kinds of primary metabolites, 44 kinds of volatile compounds, 29 kinds of free amino acids and 16 kinds of hydrolytic amino acids. After ANOVA and OPLS-DA, 52 kinds of metabolites were important with predictive VIP > 1 and p < 0.05. In FZX pericarp, the contents of many amino acids increased significantly, which might be related to the yellow-green pericarp and play an important role in delaying browning. In the pericarp of JGHN, NMC and HZ, a great number of soluble sugars and some free amino acids were induced during browning, which was negatively correlated with the browning speed of three red pericarp cultivars. The browning induced a large number of sesquiterpenes in the pericarp of FZX, NMC and HZ, which was positively correlated with the browning index. In addition, the correlation analysis showed that the amino acids were negatively correlated with the volatile compounds, suggesting that pericarp browning could induce the conversion of metabolic products from amino acids to terpenes.