In order to explore the key factors involved in the regulation of chilling injury formation in carbohydrate metabolism of peach fruit, we systematically analyzed the response of peach fruit to cold stress from physiological and transcriptomic perspectives. Cold stress in peach elevated malondialdehyde, impaired membranes, reduced sucrose via invertase-mediated hydrolysis to fructose/glucose, and may activate pentose phosphate pathway while inhibiting glycolysis pathways for metabolic maintenance and energy conservation, as suggested by phosphofructokinase and glucose-6-phosphate dehydrogenase activity shifts. Transcriptome and weighted gene co-expression network analysis revealed a series of genes respond to low-temperature stress in starch and sucrose metabolism pathway, including vacuolar invertases gene (PpVIN), hexokinase gene (PpHXK), trehalose-phosphate synthase gene (PpTPS), trehalose-phosphate phosphatase gene (PpTPP), and fructokinase gene (PpFRK), of these hub genes have been reported to resist to cold stress. In addition, by constructing co-expression network, several transcription factors (TFs) were involved in regulating hub genes related to carbohydrate metabolism in peach fruit, such as ZAT12, bZIP23, bZIP53, CBF5, and others. These TFs may serve as key regulators of the transcriptional network, modulating gene expression related to carbohydrate metabolism in response to cold stress.

Fruit and vegetables production is permanently affected by many threats including fungal pathogens, which leads to serious losses from harvest to final consumption. Chemical preservatives are effective but may pose an increased risk of drug resistance and contamination to the environment. The demand for natural substances as fungicides is gradually increasing. Tea tree oil (TTO) obtained by steam distillation of Melaleuca alternifolia, has been widely used as ‘green’ and ‘safety’ antifungal agent for many years. This paper comprehensively summarized the source, composition, extraction methods and biological functions of TTO and its applications in the storage of fruit and vegetables. In particular, we focused on the functions of TTO as antimicrobial agents to reduce the occurrence and spread of diseases and activate plants' defense system, including preservation effects, antimicrobial mechanisms and application methods. This was highly intended to help and serve as a reference for the pertinent researchers.

Rhizopus stolonifer is the major cause of soft rot in peaches, which leads to rapid decay and shortens the shelf life. In this study, we investigated the inhibitory mechanism of cinnamon essential oil (CEO) against R. stolonifer, evaluated its control efficacy of soft rot of peaches. The results showed that CEO treatment damaged the cell membrane of R. stolonifer, resulting in a high increase in extracellular conductivity and protein content. CEO causes the mycelium to crumple, as well as plasmalemma wall separation, the ablation and absence of some organelles. CEO also increased the contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2), and the accumulation of reactive oxygen species (ROS) of R. stolonifer, thus inhibiting the growth of R. stolonifer. In addition, we found that 0.8 mL L-1 CEO fumigation significantly reduced the incidence of soft rot in peaches without any adverse effect on fruit quality. Therefore, our findings provide theory and scientific guide for the application of CEO in controlling soft rot of peaches in postharvest storage. CEO could be used as a natural fungicide to reduce fungal decay in fruits.

The applications of bamboo are hindered by its poor water resistance, susceptibility to mildew, and inherent flammability - highlighting the need for effective, environmentally friendly, and cost-efficient modification methods. In this study, a green modification strategy was developed using lactic acid and taurine to enhance the overall performance of bamboo. The results demonstrated the successful in situ polymerization of lactic acid and incorporation of taurine into the bamboo matrix. The modification improved the thermal stability of bamboo, with reduced degradation rates and enhanced char formation, which intensified with increasing taurine content. Flame retardancy was notably enhanced, with reductions of 58% in peak heat release rate, 87% in total smoke production, and 29% in MARHE. Mechanical tests confirmed that the modification had a minimal impact on the bending strength and stiffness of the bamboo, while greatly improving water resistance and mildew resistance. Overall, this work demonstrates the potential of taurine as a flame-retardant additive for bamboo materials and provides a simple, eco-friendly, and effective method to enhance the water resistance, mildew resistance, and flame retardancy of bamboo, expanding its potential for broader application in sustainable material development.

This study focused on the anti-browning effect of broccoli stem extract (BE) on fresh-cut peaches. Compared to Lcysteine (L-Cys), BE showed the higher inhibition of the surface browning in fresh-cut peach fruit. This was accompanied with a more decreased polyphenol oxidase (PPO) activity and down-regulation of PpPPO expression. BE showed a non-competitive inhibition for peach PPO, and the highest inhibition rate (85.23 +/- 3.86 %) was found when PPO catalyzed the oxidation of catechol. Furthermore, sulfur-containing compounds, including methylthiouracil (MTU), S-Methyl methanethiosulfonate (MMTS) and thiophene, 2-propyl- were identified in BE and shown to inhibit PPO activity. The molecular docking also indicated that these three compounds spontaneously bound PPO via hydrogen bonding, it-it conjugation and hydrophobic interactions, resulting in the PPO inhibition and its associated browning. BE also increased the total phenol and flavonoids content as well as antioxidant capacities in fresh-cut fruit, suggested by increased activities of catalase (CAT), ascorbate peroxidase (APX) and 2, 2 '-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging rate. Therefore, BE could be a natural anti-browning agent that can be used for the inhibition of PPO-initiated discoloration in peach fruit.

The alleviation of the impact of sucrose treatment on programmed cell death (PCD) in postharvest broccoli has been reported in previous studies; however, the fundamental mechanisms are still not fully understood. This study found that exogenous sucrose treatment maintained the mitochondrial structure in broccoli buds, enhanced mitochondrial membrane potential (Delta Psi m), elevated activity of antioxidant enzymes and decreased levels of reactive oxygen species (ROS). These changes ultimately inhibited the release of Cytochrome c/a (Cytc/ a) and delayed PCD in broccoli buds. Furthermore, the expression of BoVDAC2 progressively decreased with prolonged storage. To further explore the relationship between BoVDAC2 and PCD, BoVDAC2 was overexpressed in BY-2 cells in this study. Compared to wild-type cells, BoVDAC2-overexpressing cells showed reduced mitochondrial ultrastructure damage, increased cell vitality, enhanced antioxidant enzyme activity, and decreased ROS production. Additionally, BoVDAC2 overexpression elevated energy metabolism, maintained mitochondrial membrane integrity, inhibited Cytc/a release, suppressed caspase-like activity, and improved the expression of genes related to PCD in BY-2 cells. Overall, the findings suggest that sucrose induces BoVDAC2 expression, which helps to maintain mitochondrial structure and function in postharvest broccoli buds, thereby mitigating PCD.

The advent of full-length transcriptome sequencing technologies has accelerated the discovery of novel splicing isoforms. However, existing alternative splicing (AS) tools are either tailored for short-read RNA-Seq data or designed for human and animal studies. The disparities in AS patterns between plants and animals still pose a challenge to the reliable identification and functional exploration of novel isoforms in plants. Here, we developed integrated full-length alternative splicing analysis (iFLAS), a plant-optimized AS toolkit that introduced a semi-supervised machine learning method known as positive-unlabeled (PU) learning to accurately identify novel isoforms. iFLAS also enables the investigation of AS functions from various perspectives, such as differential AS, poly(A) tail length, and allele-specific AS (ASAS) analyses. By applying iFLAS to three full-length transcriptome sequencing datasets, we systematically identified and functionally characterized maize (Zea mays) AS patterns. We found intron retention not only introduces premature termination codons, resulting in lower expression levels of isoforms, but may also regulate the length of 3'UTR and poly(A) tail, thereby affecting the functional differentiation of isoforms. Moreover, we observed distinct ASAS patterns in two genes within heterosis offspring, highlighting their potential value in breeding. These results underscore the broad applicability of iFLAS in plant full-length transcriptome-based AS research.

The effects of exogenous glutamate treatment on the quality attributes, γ-aminobutyric acid (GABA) shunt, phenylpropanoid pathway, and antioxidant capacity of fresh-cut carrots were investigated. Results showed that glutamate treatment suppressed the increases in lightness and whiteness values, inhibited the degradation of total carotenoids and maintained better flavor and taste in fresh-cut carrots. Moreover, glutamate treatment rapidly promoted the activities of glutamate decarboxylase and GABA transaminase, thus improving the GABA content. It also significantly enhanced the activities of phenylalanine ammonia-lyase, cinnamate-4-hydroxylase, and 4-coumarate coenzyme A ligase and promoted the accumulation of total phenolics as well as the main individual phenolic compounds, including chlorogenic and caffeic acid. In addition, glutamate application activated the reactive oxygen system-related enzyme including peroxidase, superoxide dismutase, ascorbate peroxidase, and catalase activities to maintain higher antioxidant capacity in fresh-cut carrots. These results demonstrated that exogenous glutamate treatment maintained better nutritional quality and alleviated color deterioration by accelerating the accumulation of GABA and phenolics and enhancing the antioxidant capacity in fresh-cut carrots.

Docosahexaenoic acid (DHA) in the form of triacylglycerols (TAG) are widely recognized for their health benefits. As naturally occurring DHA in the form of TAG are limited, this work developed and optimized a Candida rugosa lipase-catalyzed selective hydrolysis process to enrich DHA in tuna oil. The DHA-enriched tuna oil produced at optimal conditions (lipase concentration of 4 %, ratio of water to tuna oil of 1:3, reaction temperature of 55 degrees C) contained 46.12 % of DHA, in which 55.24 % of DHA was located in sn -2 position of the glycerides. In -vitro bioavailability test shows, the DHA-enriched tuna oil (7.89 %) had significantly higher cellular uptake of DHA as compared to unprocessed oil. The DHA-enriched oil demonstrated increased intracellular oxidation and mitochondrial damage of Caco -2 cell.

BACKGROUND:Ciprofloxacin is a widely used antibiotic in medicine and agriculture. It can cause pollution to the environment and food, thereby affecting human health. OBJECTIVE:This study proposes the preparation of molecular imprinted fluorescent sensors and their selective detection of ciprofloxacin, with the aim of achieving specific recognition and accurate detection of ciprofloxacin. METHODS:Rare earth metal Er3+ is added to ZnS quantum dots to prepare a molecularly imprinted fluorescence sensor (MIP/Er3+/ZnS QDs). The effects of substance concentration, pH value, and time on the fluorescence detection intensity are analyzed to determine the optimal fluorescence detection conditions. RESULTS:Experimental results showed that the sensor accurately detected ciprofloxacin with a detection limit of 31 nmol/L and the linear range of 0.1-10 μmol/L. The sensor had a recovery rate of 99.7% to 103.5% for ciprofloxacin in milk samples, with a relative standard deviation of less than 5%, indicating accurate determination of ciprofloxacin content. CONCLUSION:Molecularly imprinted fluorescent sensors have enormous application potential in the monitoring and control of ciprofloxacin, and are of great significance for ensuring environmental and food safety.

Whitening and microbial infection are two major reasons to induce quality deterioration in fresh-cut carrots. Calcium chloride (CaCl2) could enhance the quality attributes in fresh-cut carrots, but the molecular mechanism is still not illuminated. In this study, CaCl2 treatment suppressed the increases of whiteness index and total bacterial count as well as enhanced the antioxidant capacity of fresh-cut carrots. In addition, CaCl2 treatment promoted phenolics accumulation by upregulating the transcripts and enzyme activity of phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H) and 4-coumarate coenzyme A ligase (4CL) in phenylpropanoid pathway. However, this treatment inhibited the increase of enzyme activity and gene expression of cinnamyl alcohol dehydrogenase (CAD), thus suppressing lignin synthesis and whitening process in fresh-cut carrots. Moreover, a calmodulin-binding transcription activator (CAMTA) transcription factor DcCAMTA3, was induced in response to CaCl2 treatment. DcCAMTA3 activated the transcription of DcPAL1, DcC4H and Dc4CL1 genes and repressed the expression of DcCAD1 gene by directly targeting the CG-box. DcCML3/11, a calmodulin-like protein, interacted with DcCAMTA3, and this interaction enhanced DcCAMTA3-mediated transcriptional activation of DcPAL1, DcC4H and Dc4CL1 and repression of DcCAD1. Therefore, CaCl2 treatment is effective in maintaining quality and enhancing antioxidant capacity of fresh-cut carrots by the cooperative action of DcCMLs and DcCAMTA3 in positively regulating phenylpropanoid pathway.

GABA is able to increase resistance to biotic and abiotic stresses in fresh-cut fruits and vegetables. Therefore, the objective of this research was to explore the potential regulatory mechanisms of γ-aminobutyric acid (GABA) accumulation in fresh-cut stem lettuce following GABA treatment. The evidence showed that exogenous GABA stimulated the GABA shunt by elevating glutamate levels, the activities of GABA transaminase (GABA-T) and glutamate decarboxylase (GAD). Similarly, GABA stimulated polyamine metabolism by increasing the activities of 4-amino aldehyde dehydrogenase (AMADH), polyamine oxidase (PAO) and diamine oxidase (DAO), as well as elevating free polyamines, arginine and ornithine levels. Subsequently, GABA application up-regulated the expression of GABA shunt genes and polyamine metabolism genes. Additionally, GABA treatment resulted in the down-regulation of LsMYB44 and LsWRKY12 expressions. Notably, LsMYB44 bound to MYB binding sites in the LsGAD, LsGABAT1, LsADC1, LsPAO2, LsALDH7B4 promoters and repressed transcription of these genes. The interaction between LsMYB44 and LsWRKY12 was associated with the transcriptional repression of polyamine metabolism and GABA shunt genes by LsMYB44. In conclusion, LsMYB44 and LsWRKY12 downregulated the transcription of key genes of GABA shunt and polyamine metabolism in fresh-cut lettuce. This downregulation, however, was alleviated by the application of GABA, thereby promoting endogenous GABA accumulation.

Methyl jasmonate (MeJA) is a crucial cellular regulator involved in various developmental processes and defense mechanisms against environmental stresses. Hydrogen sulfide (H2S), a novel gas transmitter, has been shown to play a significant role in stress mitigation in plants. While there is established crosstalk between these two signaling molecules in plants, the evidence of their interaction within fruit remains notably insufficient. In this study, we investigated whether H2S serves as a downstream signal for MeJA during the cold storage of peach fruit. Exogenous MeJA application reduced cold damage in peach fruit, as indicated by a notable decrease in the browning index (BI) and malondialdehyde (MDA) content. This mitigation was attributed to the downregulation of polyphenol oxidase (PPO) gene family transcription in peach, like PpPPO1, PpPPO2, and PpPPO8. Furthermore, endogenous H2S levels in MeJA-treated peaches increased during storage. We performed a genome-wide analysis on H2S biosynthesis genes, PpLCDs and PpDCDs, and assessed their expression levels in peaches. Among them, PpLCD1, PpLCD3, PpLCD5, PpDES1, PpDES3, and PpDES5 were identified as contributors to H2S biosynthesis in peaches. Additionally, PpLCD3, PpLCD5, PpDES1, PpDES2, and PpDES4 were observed to transiently respond to MeJA application. Several JA signaling-related cis-elements, including TGACG-motif, CGTCA-motif, G-box, and low-temperature responsive element, were found in the promoters of these LCD/DCD genes. In vitro experiments with exogenous H2S applications further confirmed the protective role of H2S in cold-stored peaches. Our findings suggest that H2S-mediated MeJA signaling alleviates chilling injury in peach fruit during low-temperature storage.

The effects of γ-aminobutyric (GABA) on enzymatic browning, storage quality, membrane and reactive oxygen species (ROS) metabolism in fresh-cut stem lettuce were investigated. The results illustrated that GABA treatment delayed browning degree, polyphenol oxidase (PPO) activity and the expression of LsPPO. Meanwhile, higher chlorophyll and ascorbic acid contents were exhibited in GABA-treated stem lettuce, as well as the slower microbial propagation. Further investigation revealed that exogenous GABA application declined malondialdehyde content, electrolyte leakage and the enzyme activities of membrane metabolism, and the expression levels of related genes were also downregulated. In addition, GABA treatment scavenged ROS and strengthened the enzyme activities of ROS metabolism, as well as the expression levels of corresponding genes. Taken together, these findings implied that the repressed enzymatic browning and microbial propagation in GABA-treated stem lettuce were due to the inhibition of ROS accumulation, enhancement of membrane stability and increased resistance to oxidation.

Rhizopus nigricans (R. nigricans), one of the fungi that grows the fastest, is frequently discovered in postharvest fruits, it’s the main pathogen of strawberry root rot. Flavonoids in Sedum aizoon L. (FSAL) is a kind of green and safe natural substance extracted from Sedum aizoon L. which has antifungal activity. In this study, the minimum inhibitory concentration (MIC) of FSAL on R. nigricans and cell apoptosis tests were studied to explore the inhibitory effect of FSAL on R. nigricans. The effects of FSAL on mitochondria of R. nigricans were investigated through the changes of mitochondrial permeability transition pore(mPTP), mitochondrial membrane potential(MMP), Ca2+ content, H2O2 content, cytochrome c (Cyt c) content, the related enzyme activity and related genes of mitochondria. The results showed that the MIC of FSAL on R. nigricans was 1.800 mg/mL, with the addition of FSAL (1.800 mg/mL), the mPTP openness of R. nigricans increased and the MMP reduced. Resulting in an increase in Ca2+ content, accumulation of H2O2 content and decrease of Cyt c content, the activity of related enzymes was inhibited and related genes were up-regulated (VDAC1, ANT) or down-regulated (SDHA, NOX2). This suggests that FSAL may achieve the inhibitory effect of fungi by damaging mitochondria, thereby realizing the postharvest freshness preservation of strawberries. This lays the foundation for the development of a new plant-derived antimicrobial agent.

Pseudomonas fragi (P. fragi) is one of the main categories of bacteria responsible for the spoilage of chilled meat. In the processing and preservation of chilled meat, it is easy to form biofilms on the meat, leading to the development of slime on the meat, which becomes a major quality defect. Flavonoids, as one of the critical components of secondary plant metabolites, are receiving increasing attention for their antibacterial activity. Flavonoids in Sedum aizoon L. (FSAL), relying on its prominent antibacterial activity, are of research importance in food preservation and other applications. This article aims to investigate the effect of FSAL on the biofilm formation of P. fragi, to better apply FSAL to the processing and preservation of meat products. The disruption of cellular structure and aggregation properties by FSAL was demonstrated by the observation of the cellular state within the biofilm. The amount of biofilm formation was determined by crystal violet staining, and the content of polysaccharides and proteins in the extracellular wrapped material was determined. It was shown that the experimental concentrations of FSAL (1.0 MIC) was able to inhibit biofilm formation and reduce the main components in the extracellular secretion. The swimming motility assay and the downregulation of flagellin-related genes confirmed that FSAL reduced cell motility and adhesion. The downregulation of cell division genes and the lowering of bacterial metabolic activity suggested that FSAL could hinder bacterial growth and reproduction within P. fragi biofilms. KEY POINTS: • FSAL inhibited the activity of Pseudomonas fragi in the dominant meat strain • The absence of EPS components affected the formation of P. fragi biofilms • P. fragi has reduced adhesion capacity due to impaired flagellin function.

The vacuolar invertase (VIN) gene PpVIN2 is induced at chilling temperatures, and plays an important role in sucrose metabolism in peach fruit during cold storage. Using a dual membrane yeast two-hybrid system, we found 22 proteins interacted with PpVIN2. Of these, PpPGIP1 (polygalacturonase-inhibiting protein) is a leucine-rich repeat glycoprotein and sensitives to chilling temperature (5 degrees C), based on the expression level of which increased significantly accompanied with the chilling injury. Colocalization of PpPGIP1 and PpVIN2 was demonstrated by confocal microscopy and their interaction between was demonstrated by bimolecular fluo-rescence complementation (BiFC). Transient overexpression of PpPGIP1 in peach fruit increased VIN activity significantly. Transient virus-induced gene silencing of PpPGIP1 decreased VIN activity significantly, which led to decreases sucrose decomposition. PpPGIP1 recombinant protein was successfully expressed by constructing pMAL-c6T-PpPGIP1, and PpPGIP1 increased the VIN activity in vitro. Taken together, PpPGIP1 positively reg-ulates VIN activity via an interaction with PpVIN2; this interaction results in accelerated sucrose decomposition in peaches under chilling temperature. These findings provide a new perspective for understanding the new function of PpPGIP1 related with the rapid decomposition of sucrose and the occurrence of chilling injury in peach fruit during cold storage.

Brassinosteroids (BRs) are phytohormones that play numerous roles in a plant's response to environmental stress. While BES/BZR transcription factors are essential components in BR signaling, their role in regulating postharvest fruit responses to cold stress is largely unknown. In this study, the application of 24-epibrassinolide (EBR) to peaches alleviated chilling injury (CI) during postharvest cold storage. We further characterized a key BES/BZR gene, PpBZR1, which regulates peach cold resistance. Transient expression PpBZR1 in peaches showed that PpBZR1 inhibits PpVIN2 expression and VIN activity, resulting in an elevated level of sucrose, which protects fruit from CI. Arabidopsis thaliana expressing PpBZR1 that had a high germination and seedling survival rate at low temperatures, which may be due to higher level of sucrose and lower oxidative damage. Mechanistically, we confirmed that PpBZR1 directly binds to the PpVIN2 promoter and functions as a negative regulator for sucrose metabolism. In addition, PpCBF1/5/6 were induced by EBR treatment and AtCBFs were upregulated in PpBZR1 transgenic Arabidopsis thaliana. Combined with previous findings, we hypothesize that PpBZR1 regulates PpVIN2 and may also be mediated by CBF. In conclusion, PpBZR1 expression is induced by EBR treatment during cold storage, which futher inhibite sucrose degradation gene PpVIN2 transcription via direct binding its promoter and indirectly regulating PpVIN2, resulting in slower sucrose degradation and higher chilling tolerance of peach.

Botrytis cinerea is a plant pathogen, which affects the quality of fruits. However, chemical antifungal agents are extremely harmful to the environment, hence it's critical to create a natural plant-derived antifungal agent to replace chemical antifungal agents. The study explored the antifungal mechanisms of flavonoids from Sedum aizoon L. (FSAL) against B. cinerea. In the study, cell membrane served as an important breakthrough point. The minimum inhibitory concentration (MIC) of FSAL against B. cinerea was investigated. The propidium iodide (PI) staining observation of B. cinerea was explored. The activities of crucial enzymes involved in the metabolism were studied as well as the phospholipid and fatty acid changes. The expression of genes related to the membrane lipid metabolism was also measured. The results showed that FSAL had a certain inhibitory effect on B. cinerea and the MIC was 1.500 mg/mL. FSAL disrupted the cell membrane of B. cinerea, which decreased the contents of glutathione and proline at a low level as well as the membrane phospholipids. Compared with the control group, the activities of crucial enzymes were decreased, and the expression of key genes was reduced. It indicated that FSAL inhibited B. cinerea by disrupting its cell membrane, offering the possibility of a natural plant-derived antifungal agent for the preservation of fruits.

The occurrence of gray mold is the main cause of rot and spoilage in grapes, and Botrytis cinerea is the main causative agent of gray mold. The aim of this study is to clarify the inhibitory effect of flavonoids from Sedum aizoon L. (FSAL) on gray mold of grapes and to provide some basis for the development of new natural plant-derived antifungal agents. The effect of FSAL on the disease resistance of grapes was investigated by measuring the disease incidence and lesion diameter. The effect of FSAL on fruit quality was studied by measuring pondus hydrogenii (pH), total soluble solid (TSS), ascorbic acid (AA) and soluble sugar content. The activities of catalase (CAT), peroxidase (POD), phenylalanine ammonia lyase (PAL), and superoxide dismutase (SOD) were used to explore the effect of FSAL on the antioxidant capacities in grapes. The effects of FSAL on the ethylene synthesis in mitogen-activated protein kinase (MAPK) signaling pathway in grapes were investigated by measuring the levels of reactive oxygen species (ROS) and the relative expression of VvACS1 , VvACO1 , VvACO2 , and VvACO3 genes. The results showed that FSAL treatment reduced disease incidence and lesion diameter, increased AA content in fruit and thus maintained fruit quality. FSAL treatment significantly increased CAT, POD, PAL, and SOD activities in fruit, and reduced the relative expression of the genes. In conclusion, FSAL has a certain inhibitory effect on gray mold while not affecting grape quality, and delays the ripening and aging of fruit.