& Maubl.-induced pericarp browning and disease development of harvested longan fruit

Bacillus amyloliquefaciens LY-1 culture broth enhances the storage properties of fresh litchi through acting on ROS metabolism

The impacts of Bacillus amyloliquefaciens LY-1 culture broth (BLCB) on the fruit storage properties and reactive oxygen species (ROS) metabolism of postharvest 'Wuye' litchis were studied. In comparation with control fruit, BLCB-treated litchis showed a lower fruit disease index, a higher rate of commercially acceptable fruit, higher amounts of pericarp pigments (total phenolics, anthocyanin, carotenoid, chlorophyll and flavonoid), higher chromaticity C, a*, b* and L* values but lower hue angle h° of fruit surface. Additionally, BLCB-treated litchis exhibited lower malonaldehyde (MDA) accumulation and superoxide anion radical (O2.-) production rate, higher APX, CAT and SOD activities, higher GSH and AsA amounts, higher reducing power, and higher ability of scavenging DPPH radical. Furthermore, the pericarp browning index and fruit disease index were positively correlated with O2.- production rate. These findings suggested that BLCB treatment increased the storability of postharvest litchi fruit through enhancing scavenging capacity of ROS and inhibiting overaccumulation of ROS.

Effects of reactive oxygen species on fruit ripening and postharvest fruit quality

Reactive oxygen species (ROS) serve as important signaling molecule, involved in numerous biological processes, particularly in the physiological changes associated with fruit ripening and postharvest handing. This review explores ROS key role in plant fruit ripening and postharvest quality. The mechanism of ROS production and degradation in maintaining ROS homeostasis are analyzed in detail. Fruit ripening is a complex and highly coordinated process involving physiological and biochemical changes. Studies have observed that the content of ROS, mainly hydrogen peroxide (H2O2), dynamically changes in various types of fruits during ripening. Furthermore, ROS have significant effects on fruit softening, color change, and other ripening processes. In addition, in the postharvest stage, the abnormal accumulation of ROS isclosely related to the decline in fruit quality and the occurrence of decay browning, which seriously affects the market value and shelf life of fruit. Overall, this review demonstrates the crucial role of ROS in regulating the ripening process and postharvest quality of fruit.

Combined ultraviolet-C radiation and L-cysteine treatment improves the post-harvest quality and volatile compounds of edible Lanzhou lily bulbs (Lilium davidii var. unicolor) by regulating reactive oxygen species metabolism

Lanzhou lily bulbs (Lilium davidii var. unicolor) are Chinese traditional edible fruits; however, industrial benefits are limited owing to ineffective post-harvest preservation technology. This study investigated the effect of 4.5 kJ/m2 ultraviolet (UV)-C radiation and 2.0 g/L L-cysteine (L-cys) treatment on storage quality and reactive oxygen species (ROS) metabolism in lily bulbs. The combined UV-C/L-cys treatment inhibited the increase in decay rate, weight loss, ∆E⁎ and reducing sugar content; delayed the decrease of firmness and starch content; retained aromatic volatile compounds; and reduced pungent compounds. UV-C/L-cys treatment reduced H2O2 content, O2 ·- production rate, lipoxygenase activity and malondialdehyde content by maintaining high ROS-scavenging enzymes (superoxide dismutase and catalase) activities and substances (total phenolic and ascorbic acid) levels, thereby protecting mitochondrial structure. Mantel test indicated that post-harvest quality and volatile compounds were closely related to ROS metabolism. Hence, UV-C/L-cys treatment can efficiently delay lily bulb senescence by reducing ROS accumulation during storage.

Biochar and arbuscular mycorrhizal fungi promote rapid-cycling Brassica napus growth under cadmium stress

PURPOSE

To explore the mechanisms of tolerance of Brassica napus to ultra-high concentration cadmium pollution and the synergistic effects of biochar (BC) and Arbuscular mycorrhizal fungi (AMF) on plant growth under cadmium (Cd) stress.

RESULTS

The application of 5 % BC and inoculation with 10 g AMF significantly promoted the growth and development of B. napus. The combined application of BC and AMF (BC1A and BC2A) was better than the single application. At the Cd 200 mg/kg level, BC1A increased the fresh weight and Cd content of the above-ground parts of B. napus by 35.5 % and decreased by 21.20 %. The SOD and POD activities increased by 30.63 % and 73.37 %. The MDA and H2O2 contents decreased by 40.8 % and 69.99 %, soluble sugar content increased by 37.96 %. At the Cd 300 mg/kg level, BC1A increased the fresh weight and Cd content of the above-ground parts of B. napus by 32.8 % and decreased by 15.99 %. The SOD and POD activities increased by 39.06 % and 93.56 %. The MDA and H2O2 contents decreased by 28.39 % and 72.45 %, and the soluble sugar content increased by 21.16 %. Overall, both BC and AMF treatments alone or in combination (BC1A) were able to alleviate Cd stress and promote plant growth, with the combination of biochar and AMF being the most effective. Furthermore, transcriptome analyses indicated that BC may improve cadmium resistance in B. napus by significantly up-regulating the expression of genes related to peroxidase, photosynthesis, and plant MAPK signaling pathways. AMF may alleviate the toxicity of Cd stress on B. napus by up-regulating the expression of genes related to peroxisomes, phytohormone signaling, and carotenoid biosynthesis. The results of the study will provide support for ecological restoration technology in extremely heavy metal-polluted environments and provide some reference for the application and popularization of BC and AMF conjugation technology.

Pathological Characterization and Management of Lasiodiplodia theobromae, a Hemibiotroph with an Interkingdom Host Range

Heart rot disease, caused by Lasiodiplodia theobromae, is destructive for date palms and other woody plants. The disease was reported in several oases in Egypt, and the pathogen was found in association with infected trees suffering dieback and rachis blight. Seven phylogenetically distinct fungal isolates were selected, and their pathogenicity was confirmed on date palms. The isolates exhibited variable degrees of virulence on inoculated leaves, which confirms the variation. We examined the antifungal effect of microbial bioagents and plant extracts on heart rot disease. The isolates of Trichoderma spp. gave moderate reduction of the pathogen's linear growth (40 to 60%), whereas their exudates were ultimately ineffective. Bacillus spp. isolates, except for B. megaterium, were more effective against spore germination, giving 80 to 90% reduction on average. Among the examined plant extracts, garlic sap gave 98.67% reduction of linear growth followed by artemisia (15.5%) and camphor (24.8%). The extraction methods greatly influenced the antifungal efficiency of each extract because exposure to organic solvents significantly decreased the efficiency of all extracts, whereas hot water extraction negatively affected garlic sap only. Successful bioagents and plant extracts were further assayed for the suppression of heart rot disease on date palms. Both T. album and T. harzianum gave comparable degrees of suppression as by commercial fungicides. In addition, treatment before or during pathogen inoculation was the most effective because it significantly enhanced the expression of defense-related enzymes. Our findings suggest biopesticides possess a dual role in disease suppression and defense boosters for date palms suffering heart rot disease.

Acidic electrolyzed-oxidizing water treatment mitigated the disease progression in Phomopsis longanae Chi-infected longans by modulating ROS and membrane lipid metabolism

Postharvest harmful pathogenic infestation leads to rapid decay in longan fruit. Compared with P. longanae-infected longans, AEOW alleviated fruit disease severity and diminished the O2-. production rate and MDA content. It also increased APX, CAT, and SOD activities, delayed the decrease in the levels of GSH and AsA, as well as the reducing power and DPPH radical scavenging ability, which resulted in a decline in membrane lipid peroxidation in P. longanae-infected longans. Additionally, AEOW reduced LOX, lipase, PI-PLC, PC-PLC, and PLD activities, maintained higher levels of PC, PI, IUFA, USFAs, and U/S, while reducing levels of PA, DAG, SFAs, and CMP. These effects alleviated membrane lipid degradation and peroxidation in P. longanae-infected longans. Consequently, AEOW effectively maintained membrane integrity via improving antioxidant capacity and suppressing membrane lipid peroxidation. This comprehensive coordination of ROS and membrane lipid metabolisms improved fruit resistance and delayed disease development in longans.

Near-freezing temperature suppresses avocado (Persea americana Mill.) fruit softening and chilling injury by maintaining cell wall and reactive oxygen species metabolism during storage

To enhance the postharvest quality of avocado (Persea americana Mill.) fruit, this study investigates alterations in cell wall metabolism and reactive oxygen species (ROS) metabolism during near-freezing temperature (NFT) storage, and explores their impact on fruit softening. The fruit was stored at 25 °C, 5 °C, 2 °C, and NFT, respectively. NFT storage retarded firmness loss and chilling injury in comparison with 25 °C, 5 °C, and 2 °C. NFT storage delayed the decrease of ionic-soluble pectin (ISP) and cellulose (CLL) contents by suppressing cell wall degradation enzyme activities. Correlation analysis showed that cell wall degradation enzyme activities were positively correlated to rates of ethylene release and respiration. Moreover, NFT storage maintained higher levels of DPPH and ABTS scavenging abilities, activities of superoxide dismutase, peroxidase, and catalase, as well as ascorbate-glutathione cycle (ascorbic acid, glutathione, glutathione disulfide, ascorbate peroxidase, cycle-related enzymes), thereby inhibited the increase of ROS content, malondialdehyde content, and cell membrane permeability. Fruit firmness and chilling injury were correlated with the contents of hydrogen (H2O2), superoxide anion (O2.-), ISP, and CLL. These results suggested that NFT could suppress fruit softening and chilling injury by inhibiting cell wall degradation through delaying respiration and ethylene production and suppressing ROS production via activation of antioxidant systems, thereby maintaining quality and prolonged storage life during avocado fruit storage.

Analyzing the impacts of cadmium alone and in co-existence with polypropylene microplastics on wheat growth

Heavy metals typically coexist with microplastics (MPs) in terrestrial ecosystems. Yet, little is known about how the co-existence of heavy metals and MPs affect crops. Therefore, this study aimed to evaluate the impact of cadmium (Cd; 40 mg/L) alone and its co-existence with polypropylene (PP)-MPs (50 and 100 µm) on seed germination, root and shoot growth, seedling dry weight (DW), and antioxidant enzyme activities of wheat. The study demonstrated that the germination rate of wheat did not vary significantly across treatment groups. Yet, the inhibitory impact on wheat seed germination was strengthened under the co-existence of Cd and PP-MPs, as the effect of a single treatment on seed germination was non-significant. The germination index and mean germination time of wheat seeds were not affected by single or combined toxicity of Cd and PP-MPs. In contrast, Cd and PP-MPs showed synergistic effects on germination energy. Wheat root and shoot length were impeded by Cd alone and in combination with PP-MPs treatments. The DW of wheat seedlings showed significant change across treatment groups until the third day, but on the seventh day, marginal differences were observed. For example, on third day, the DW of the Cd treatment group increased by 6.9% compared to CK, whereas the DW of the 100 µm PP-MPs+Cd treatment group decreased by 8.4% compared to CK. The co-occurrence of Cd and PP-MPs indicated that 50 μm PP-MPs+Cd had an antagonistic impact on wheat seedling growth, whereas 100 μm PP-MPs+Cd had a synergistic impact due to the larger size of PP-MPs. The antioxidant enzyme system of wheat seeds and seedlings increased under single Cd pollution, while the activities of superoxide dismutase, catalase, and peroxidase were decreased under combined pollution. Our study found that Cd adversely affects wheat germination and growth, while the co-existence of Cd and PP-MPs have antagonistic and synergistic effects depending on the size of the PP-MPs.

Ursolic acid, the main component of blueberry cuticular wax, inhibits Botrytis cinerea growth by damaging cell membrane integrity

Cuticular wax has been reported to play an essential role in resisting pathogens in various fruits. This study investigated the antifungal ability of the components in blueberry cuticular wax. We showed that the cuticular wax of blueberry inhibited the growth of Botrytis cinerea and ursolic acid (UA) was the key antifungal compound. UA inhibited B. cinerea growth in vitro and in vivo. Furthermore, UA increased extracellular conductivity and cellular leakage in B. cinerea, deformed the mycelial morphology, and destroyed cell ultrastructure. We also demonstrated that UA stimulated the accumulation of reactive oxygen species (ROS) and inactivated ROS scavenging enzymes. These results indicate that UA may exert antifungal effects against B. cinerea by disrupting cell membrane integrity. Thus, UA has significant potential as an agent for the control of gray mold in blueberry.

Phytic acid is a new substitutable plant-derived antifungal agent for the seedling blight of Pinus sylvestris var. mongolica caused by Fusarium oxysporum

Phytic acid (PA) is a new substitutable plant-derived antifungal agent; however, few reports have been published regarding its antifungal effects on pathogenic fungi. The present study explored the in vitro antifungal activity of PA against four phytopathogenic fungi and found that PA was the most effective at inhibiting the growth of Fusarium oxysporum. This study aimed to investigate the in vivo and in vitro antifungal activities of PA against the seedling blight of Pinus sylvestris var. mongolica caused by F. oxysporum and to determine its possible mechanism of action. The results showed that PA inhibited spore germination and mycelial growth of F. oxysporum in a concentration-dependent manner and exhibited strong inhibition when its concentration exceeded 1000 mg/L. It mainly destroyed the integrity of the cell membrane, increasing its cell membrane permeability, causing the cell contents to spill out, and impairing fungal growth. In addition, the leakage of intercellular electrolytes and soluble proteins indicated that PA used at its EC₂₀ and EC₅₀ increased the membrane permeability of F. oxysporum. The increase in malondialdehyde and hydrogen peroxide content confirmed that PA treatment at its EC₂₀ and EC₅₀ damaged the cell membrane of the pathogen. Scanning electron microscopy revealed that PA affected the morphology of mycelia, causing them to shrivel, distort, and break. Furthermore, PA significantly reduced the activities of the antioxidant-related enzymes superoxide dismutase and catalase, as well as that of the pathogenicity-related enzymes polygalacturonase, pectin lyase, and endoglucanase (EG) in F. oxysporum (P < 0.05). In particular, EG enzyme activity was maximally inhibited in F. oxysporum treated with PA at its EC₅₀. Moreover, PA significantly inhibited the incidence of disease, and growth indices in Pinus sylvestris var. mongolica seedling blight was determined. In summary, PA has a substantial inhibitory effect on F. oxysporum. Therefore, PA could serve as a new substitutable plant-derived antifungal agent for the seedling blight of P. sylvestris var. mongolica caused by F. oxysporum.

Characterization of Octa-aminopropyl polyhedral oligomeric silsesquioxanes (OA-POSS) nanoparticles and their effect on sweet basil (Ocimum basilicum L.) response to salinity stress

Salt stress is of the most detrimental abiotic stress factors on either crop or non-crop species. Of the strategies employed to boost the performance of the plants against harmful impacts of salt stress; application of novel nano-engineered particles have recently gained great attention as a promising tool. Octa-aminopropyl polyhedral oligomeric silsesquioxanes nanoparticles (OA-POSS NPs) were synthesized and then a foliar-application of OA-POSS NPs were carried out on sweet basil plants subjected to the salt stress. In that context, interactive effects of OA-POSS NPs (25, 50 and 100 mg L^-1) and salinity stress (50 and 100 mM NaCl) were assayed by estimating a series of agronomic, physiological, biochemical and analytical parameters. OA-POSS NPs decreased the harmful effects of salinity by increasing photosynthetic pigment content, adjusting chlorophyll fluorescence, and triggering non-enzymatic (phenolic content) and enzymatic antioxidant components. The findings suggested that 25 mg L^-1 OA-POSS NPs is the optimum concentration for sweet basil grown under salt stress. Considering the essential oil profile, estragole was the predominant compound with a percentage higher than 50% depending on the treatment. In comparison to the control group, 50 mM NaCl did not significantly affect estragole content, whilst 100 mM NaCl caused a substantial increase in estragole content. Regarding OA-POSS NPs treatments, increments by 16.8%, 11.8% and 17.5% were observed following application with 25, 50 and 100 mg L^-1, respectively. Taken together, the current study provides evidence that POSS NPs can be employed as novel, 'green' growth promoting agents in combating salt stress in sweet basil.

Molecular mechanisms of toxicity and detoxification in rice (Oryza sativa L.) exposed to polystyrene nanoplastics

Nanoplastics (NPs) are an emerging threat to higher plants in terrestrial ecosystems. However, the molecular of NP-related phytotoxicity remains unclear. In the present study, rice seedlings were exposed to polystyrene (PS, 50 nm) NPs at 0, 50, 100, and 200 mg/L under hydroponic conditions to investigate the induced physiological indices and transcriptional mechanisms. We found that 50, 100, and 200 mg/L PS significantly reduced root (53.05%, 49.61%, and 57.58%, respectively) and shoot (54.63%, 61.56%, and 62.64%, respectively) biomass as compared with the control seedlings. The activities of antioxidant enzymes, including catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and ascorbate peroxidase (APX), were significantly activated in all PS treatment groups, indicating that PS inhibited plant growth and induced oxidative stress. Transcriptome analyses showed that PS modulated the expression of the genes involved in cell detoxification, active oxygen metabolism, mitogen-activated protein kinase (MAPK), and plant hormone transduction pathways. Our study provides new insights into phytotoxicity by demonstrating the potential underlying toxicity of PS NPs in higher plants.

Toxicological effects and transcriptome mechanisms of rice (Oryza sativa L.) under stress of quinclorac and polystyrene nanoplastics

The absorption and accumulation of nanoplastics (NPs) by plants is currently attracting considerable attention. NPs also tend to adsorb surrounding organic pollutants, such as pesticides, which can damage plants. However, molecular mechanisms underlying the phytotoxicity of NPs are not sufficiently researched. Therefore, we analyzed the toxicological effects of 50 mg/L polystyrene NPs (PS 50 nm) and 5 mg/L the herbicide quinolinic (QNC) on rice (Oryza sativa L.) using 7-day hydroponic experiments, explaining the corresponding mechanisms by transcriptome analysis. The main conclusion is that all treatments inhibit rice growth and activate the antioxidant level. Compared with CK, the inhibition rates of PS, QNC, and PS+QNC on rice shoot length were 3.95%, 6.68%, and 11.43%, respectively. The gene ontology (GO) term photosynthesis was significantly enriched by QNC, and the combination PS+QNC significantly enriched the GO terms of amino sugar and nucleotide sugar metabolisms. The chemicals QNC and PS+QNC significantly affected the Kyoto Encyclopedia of Genes and Genomes (KEGG) of the MAPK signaling pathway, plant hormone signal transduction, and plant-pathogen interaction. Our findings provide a new understanding of the phytotoxic mechanisms and environmental impacts of the interactions between NPs and pesticides. It also provides insights into the impact of NPs and pesticides on plants in the agricultural system.

Biochemical Mechanism of Fresh-Cut Lotus (Nelumbo nucifera Gaertn.) Root with Exogenous Melatonin Treatment by Multiomics Analysis

Browning limits the commercial value of fresh-cut lotus root slices. Melatonin has been reported to play crucial plant roles in growth and development. However, the mechanisms in repressing the browning of fresh-cut lotuses are still unclear. In this study, fresh-cut lotus root slices were treated with melatonin, the physical signs of browning were tested, and then the selected samples (0 d, 6 d, 12 d) were used in multiomics analysis. Fresh-cut lotus root slices with a thickness of 4 mm were soaked in a 40 mmol/L melatonin solution for 10 min; then, the slices were packed in pallets and packages and stored at 10 ± 1 °C. The results show that the 40 mmol/L melatonin selected for repressing the browning of lotus roots significantly delayed the decrease in water, total soluble solid content, and Vitamin C, decreased the growth of microorganisms, enhanced total phenolic content, improved total antioxidant capacity, and decreased ·OH, H₂O₂, and O₂^-· contents. Moreover, this treatment enhanced phenylalanine ammonialyase, polyphenol oxidase, superoxide dismutase, and catalase activities and reduced peroxidase activities and soluble quinones. NnSOD (104590242), NnCAT (104609297), and some NnPOD genes showed a similar transcript accumulation pattern with enzyme activity. It can be seen from these results that exogenous melatonin accelerated an enhancement in the antioxidant system and AsA-GSH cycle system by regulating ROS-metabolism-related genes, thereby improving the capacity to withstand browning and the quality of lotus root slices. The microbiome also showed that melatonin suppressed the fertility of spoilage organisms, such as Pseudomonas, Tolumonas, Acinetobacter, Stenotrophomonas, and Proteobacteria. Metabonomics data uncovered that the metabolites of flavonoid biosynthesis, phenylpropanoid biosynthesis, tyrosine metabolism, and phenylalanine metabolism were involved in the process.

Integrated Physiological and Metabolomic Analyses Reveal the Differences in the Fruit Quality of the Blueberry Cultivated in Three Soilless Substrates

With improving living standards, traditional blueberry planting modes cannot meet commercial demands, and blueberry cultivation with soilless substrate has become a popular solution in the blueberry industry. In this study, different soilless substrate treatments were found to markedly influence fruit appearance and intrinsic quality. The fruit in the 50:50 peat/pine bark (v/v) (FPB) treatment group had the maximum single fruit weight, largest vertical diameter, and brightest color, as well as the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) value, solid-acid ratio and anthocyanin content. The fruit in the 50:50 pine bark/rice husk (v/v) (FBR) treatment group had the highest total phenol and flavonoid levels, largest drip loss value, and lowest total pectin content and firmness value. Metabolomic analysis showed that flavonoid, carbohydrate, and carbohydrate conjugate, and amino acid, peptide, and analog levels were significantly different between groups. Fruit in the FPB group had the highest sucrose, D-fructose 1,6-bisphosphate, salidroside, tectorigenin, naringenin chalcone, trifolirhizin, and galangin contents. The increase in the relative expression of phenylalanine (Phe) promoted the synthesis of fruit polyphenols in the FBR group. Our results provide new insights into the effects of different substrates on the quality of blueberries and a reference for the soilless substrate cultivation of blueberries.

MIR390 Is Involved in Regulating Anthracnose Resistance in Apple

As an important cash crop in China, apple has a good flavor and is rich in nutrients. Fungal attacks have become a major obstacle in apple cultivation. Colletotrichum gloeosporioides is one of the most devastating fungal pathogens in apple. Thus, discovering resistance genes in response to C. gloeosporioides may aid in designing safer control strategies and facilitate the development of apple resistance breeding. A previous study reported that 'Hanfu' autotetraploid apple displayed higher C. gloeosporioides resistance than 'Hanfu' apple, and the expression level of mdm-MIR390b was significantly upregulated in autotetraploid plants compared to that in 'Hanfu' plants, as demonstrated by digital gene expression (DGE) analysis. It is still unclear, however, whether mdm-MIR390b regulates apple anthracnose resistance. Apple MIR390b was transformed into apple 'GL-3' plants to identify the functions of mdm-MIR390b in anthracnose resistance. C. gloeosporioides treatment analysis indicated that the overexpression of mdm-MIR390b reduced fungal damage to apple leaves and fruit. Physiology analysis showed that mdm-MIR390b increased C. gloeosporioides resistance by improving superoxide dismutase (SOD) and peroxidase (POD) activity to alleviate the damage caused by O₂^- and H₂O₂. Our results demonstrate that mdm-MIR390b can improve apple plants' anthracnose resistance.

Controlled Atmosphere Improves the Quality, Antioxidant Activity and Phenolic Content of Yellow Peach during the Shelf Life

Controlled atmosphere (CA) has been demonstrated to maintain the shelf-life quality of fruits, but its effect on the antioxidant activities and phenolic content of yellow peach is not comprehensive. This study analyzed the role of CA on the quality of shelf period, phenolic content and antioxidant activity of "Jinxiu" yellow peach. Yellow peach was left under specific aeration conditions (3.5-4% CO2, 2-3% O2, 92-95.5% N2, 1 ± 0.5 °C) and the control (1 ± 0.5 °C) for 21 d, to observe changes in physiological parameters of the fruit during 10 d of the shelf life (25 ± 1 °C). The result showed that CA reduced the weight loss rate (WLR), decay rate (DR), and browning index (BI) of yellow peaches. Furthermore, the CA held a high level of total flavonoid content (TFC), total phenol content (TPC) and phenolic content in the fruit. Antioxidant analysis showed that polyphenol oxidase (PPO) enzyme activity was lower and free radical scavenging capacity (DPPH, ABTS, and FRAP) and antioxidant enzyme activities (POD and PAL) were higher in the CA group. Combining the results of significance analysis, correlation analysis, principal component analysis (PCA) and hierarchical cluster analysis (HCA) clearly identified the differences between the CA group and the control group. The results showed that the CA could maintain higher phenolic content and reduce the oxidation of yellow peach fruit and enhance fruit quality by affecting the antioxidant activities of yellow peach.

Effects of individual and combined polystyrene nanoplastics and phenanthrene on the enzymology, physiology, and transcriptome parameters of rice (Oryza sativa L.)

Owing to their wide distribution, easy production, and resistance to degradation, microplastics (MPs) represent a globally emerging group of pollutants of concern. Furthermore, their decomposition can result in the generation of nanoplastics (NPs), which cause further environmental issues. Currently, the impact of the combination of these plastics with other organic pollutants on crop growth remains poorly investigated. In this study, a hydroponic experiment was conducted for seven days to evaluate the effects of 50 nm, 50 mg/L polystyrene (PS), and 1 mg/L phenanthrene (Phe) on the growth of rice plants. The results revealed that both Phe and PS inhibited growth and improved the antioxidant potential of rice. Relative to Phe alone, exposure to a combination of PS and Phe reduced Phe accumulation in the roots and shoots by 67.73% and 36.84%, respectively, and decreased the pressure on the antioxidant system. Exposure to Phe alone destroyed the photosynthetic system of rice plant leaves, whereas a combination of PS and Phe alleviated this damage. Gene Ontology (GO) analysis of the rice transcriptomes revealed that detoxification genes and phenylalanine metabolism were suppressed under exposure to Phe, which consequently diminished the antioxidant capacity and polysaccharide synthesis in rice plants. Kyoto Encyclopaedia of Genes and Genomes (KEGG) transcriptome analysis revealed that the combined presence of both PS and Phe improved photosynthesis and energy metabolism and alleviated the toxic effects of Phe by altering the carbon fixation pathway and hormone signal transduction in rice plants. The combination of PS and Phe also prevented Phe-associated damage to rice growth. These findings improve our understanding of the effects of MP/NPs and polycyclic aromatic hydrocarbons on crops.

Pathogenicity Factors of Botryosphaeriaceae Associated with Grapevine Trunk Diseases: New Developments on Their Action on Grapevine Defense Responses

Botryosphaeriaceae are a family of fungi associated with the decay of a large number of woody plants with economic importance and causing particularly great losses in viticulture due to grapevine trunk diseases. In recent years, major advances in the knowledge of the pathogenicity factors of these pathogens have been made possible by the development of next-generation sequencing. This review highlights the knowledge gained on genes encoding small secreted proteins such as effectors, carbohydrate-associated enzymes, transporters and genes associated with secondary metabolism, their representativeness within the Botryosphaeriaceae family and their expression during grapevine infection. These pathogenicity factors are particularly expressed during host-pathogen interactions, facilitating fungal development and nutrition, wood colonization, as well as manipulating defense pathways and inducing impacts at the cellular level and phytotoxicity. This work highlights the need for further research to continue the effort to elucidate the pathogenicity mechanisms of this family of fungi infecting grapevine in order to improve the development of control methods and varietal resistance and to reduce the development and the effects of the disease on grapevine harvest quality and yield.

Eugenol treatment delays the flesh browning of fresh-cut water chestnut (Eleocharis tuberosa) through regulating the metabolisms of phenolics and reactive oxygen species

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1.5 % EUG exhibited best inhibitory effect on browning in fresh-cut water chestnut.

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Phenylalanine ammonia-lyase of surface tissue was inhibited after eugenol treatment.

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Eugenol inhibited browning in fresh-cut water chestnut by regulating ROS metabolism.

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Eugenol enhanced ROS-scavenging enzymes and antioxidant capacity in surface tissue.

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Eugenol increased phenolic content and antioxidant capacity of inner tissue.

The potential mechanism behind the browning inhibition in fresh-cut water chestnuts (FWC) after eugenol (EUG) treatment was investigated by comparing the difference in browning behavior between surface and inner tissues. EUG treatment was found to inactivate browning-related enzymes and reduce phenolic contents in surface tissue. Molecular docking further confirmed the hydrophobic interactions and hydrogen bonding between EUG and phenylalanine ammonia-lyase (PAL). Moreover, EUG also enhanced reactive oxygen species (ROS)-scavenging enzyme activities, ultimately decreasing the O₂^- generation rates. Regarding inner tissue, EUG induced the accumulation of colorless phenolic compounds and increased the antioxidant capacity. In conclusion, 1.5 % EUG exhibited the best inhibitory effect on FWC browning, which partly attribute to the direct inhibitory effects on PAL activity. Furthermore, EUG could also enhance the enzymatic/non-enzymatic antioxidant capacity and alleviate the ROS damage to membranes, thereby, preventing the contact between oxidative enzymes and phenols and indirectly inhibiting the enzymatic browning in FWC.

Botrytis cinerea mediated cell wall degradation accelerates spike stalk browning in Munage grape

Munage grape (Vitis vinifera L. cv. Munage.) is a unique cultivar in southern Xinjiang, China. Spike stalk browning in this species has becomes more common in recent years, negatively impacting the shelf life, and causing severe economic losses during storage. This study investigated the changes in metabolisms of cell wall by Botrytis cinerea infection in association with spike stalk browning. Morphological and physiological observations showed that preharvest B. cinerea infection accelerates the spike stalk browning during storage in Munage grapes by promoting cell wall degradation. Accordingly, the cell structures in infected spike stalk showed severe collapse, while the cell structures in uninfected spike stalk remained relatively complete. Furthermore, the contents of CDTA-soluble pectin (CSP), Na₂ CO₃ -soluble pectin (NSP), cellulose, and hemicellulose were reduced, while the water-soluble pectin (WSP) content was increased during infection. In addition, the activities of polygalacturonase (PG), pectin methylesterase (PME), beta-galactosidase (β-Gal), and cellulase (Cx) were highly promoted by B. cinerea. Correspondingly, the expression levels of VvPG were markedly upregulated after inoculation and played a major role in cell wall degradation. Additionally, the spike stalk inoculated by B. cinerea showed higher activities of PPO and POD, and content of total phenolics. These results contribute to elucidating the relationship between cell wall degradation induced by B. cinerea during spike stalk browning and provide a basis for future research on improving the ability of the host cell wall to resist degrading enzymes. PRACTICAL APPLICATIONS: Botrytis cinerea is the main fungal pathogen causing the gray mold of grapes. It usually enters the tissue early in crop development, has a long incubation period, and rapidly infects the tissue when the environment is favorable and the host physiology changes. Gray mold has been reported as one of the major postharvest diseases of grapes. However, there are relatively few reports on the pathways through which B. cinerea causes the browning of grape stalks. Controlling browning caused by B. cinerea may require clarification of the physiological and molecular mechanisms by which browning occurs. The elucidation of the role of B. cinerea in causing browning of grape stalks through the cell wall degradation pathway will help to provide scientific basis for further controlling browning, maintaining freshness of stalks, developing biological agents to prevent browning, improving grape quality, and extending storage period.

Phomopsis longanae Chi causing the pulp breakdown of fresh longan fruit through affecting reactive oxygen species metabolism

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P. longanae raised longan pulp O₂^–. generation rate and contents of H₂O₂ and MDA.

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P. longanae reduced ROS scavenging enzymes activities (CAT, SOD, APX) in longan pulp.

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P. longanae lowered the amounts of endogenous antioxidant substances in longan pulp.

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P. longanae decreased longan pulp DPPH radical scavenging ability and reducing power.

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P. longanae stimulated longan pulp breakdown via reducing ROS scavenging capacity.

Phomopsis longanae Chi is a crucial pathogen causing fruit spoilage in postharvest fresh longan. The influence of P. longanae invasion with a suspension containing 1 × 10⁴P. longanae spores per mL on the breakdown occurrence and ROS metabolism in pulp of longan cv. Fuyan during storage at 28 °C was explicated. Compared to control group, more severe development of pulp breakdown (PB), higher PB index, O₂^–. generation rate, H₂O₂ and MDA content, but lower SOD, APX and CAT activities, GSH, AsA, flavonoid and total phenolics amounts, ability of scavenging DPPH radical, and reducing power were displayed in the pulp of P. longanae-infected fruit during days 0–5. In this context, P. longanae induced breakdown of longan pulp by reducing the scavenging ability of ROS and increasing the cumulation of ROS, thereby enhancing the structural collapse and lipid peroxidation of cell membrane, which were responsible for the PB of harvested longans.

The Influence of a Novel Chitosan-Based Coating with Natural Antimicrobial Agents on the Storage Properties and Reactive Oxygen Species Metabolism of Harvested Tangelo Fruit

This study investigated the effects of a novel antibacterial film based on chitosan, carboxymethyl cellulose, sodium alginate, tea polyphenols, ascorbic acid, and tangelo peel extract on the postharvest quality and reactive oxygen species metabolism of tangelo fruit during storage. The composite film significantly reduced the fruit decay rate and weight loss, delayed the reduction in total soluble solids and titratable acidity, and retained fruit firmness and the appearance of tangelo fruit during storage. Furthermore, the composite film effectively reduced the fruit respiration rate, inhibited the increase in cell-membrane permeability, markedly reduced the generation of superoxide anion, hydrogen peroxide, and malondialdehyde, and enhanced the activity of the antioxidant enzymes superoxide dismutase, catalase, and ascorbate peroxidase. The composite film also reduced losses of the nonenzymatic antioxidants ascorbic acid and glutathione. Overall, the chitosan-based composite antibacterial film effectively maintained the quality of tangelo fruit during storage, enhanced ROS scavenging capacity and antioxidant properties, and then reduced the rot rate of postharvest tangelo.

Phytic Acid Treatment Inhibits Browning and Lignification to Promote the Quality of Fresh-Cut Apples during Storage

Browning and lignification often occur in fresh-cut apple processing, leading to quality deterioration and limiting the shelf life of products. In this study, 0.8% (v/v) phytic acid was used to improve the quality and shelf life of fresh-cut apples. From the results, the browning was inhibited by the phytic acid treatment and the browning index (BI) of the control fruit was 1.62 times that of phytic acid treatment at 2 d of storage. The lignin content in phytic acid-treated fruit significantly decreased at 2, 4, and 6 d of storage compared to the control. Phytic acid treatment also reduced H₂O₂ and malonaldehyde (MDA) contents, which may indicate lighter membrane damage to apples. Compared with the control, the polyphenol oxidase (PPO) and peroxidase (POD) activities decreased while superoxide dismutase (SOD) and catalase (CAT) activities increased in phytic acid-treated fruit. Consistent with the lignin content, the activities of phenylpropane metabolism-related enzymes phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H), and 4-coumarate: CoA ligase (4CL) were inhibited by phytic acid treatment. In conclusion, phytic acid alleviated the browning and lignification of fresh-cut apples by reducing PPO and POD activities, maintaining cell membrane integrity, and inhibiting phenylpropane metabolism.

Fungal and Oomycete Diseases of Minor Tropical Fruit Crops

Minor tropical fruits are grown on a small scale and provide income to smallholder farmers. The cultivation of these fruit crops indirectly contributes to the economy of producing countries as well as to food and crop security. Dragon fruits, guava, passionfruit, lychee, longan, mangosteen, durian, and rambutan are common minor fruit crops. In recent years, the international trade of some of these minor tropical fruits, particularly dragon fruit, passionfruit, guava, and lychee, has increased due to their nutritional value, with various health benefits. Similar to other crops, minor fruit crops are susceptible to fungal and oomycete diseases. These diseases negatively affect the yield and quality of fruit crops, leading to substantial losses. In this context, the knowledge of disease types and causal pathogens is fundamental to develop suitable disease management practices in the field as well as appropriate post-harvest treatments.

Effects of dehydration speed on the metabolism of membrane lipids and its relation to the browning of the Thompson seedless grape

Xinjiang is the main producing area of raisins and the largest green raisins production base in China. The browning of Thompson seedless grape raisin is extremely serious during drying process, which has become the key issue in the development of Xinjiang raisin industry. Previous studies have shown that the dehydration speed has a great impact on the browning of Thompson seedless grape, but few relevant mechanisms have been studied. Here, we demonstrate the effect of dehydration speed on the lipid metabolism and its relation to the browning of the Thompson seedless grape during drying. Compared to slow dehydration treatment, the rapid dehydration treatment of the Thompson seedless grape exhibited a lower degree of browning and activities of lipoxygenase (LOX), a higher index of unsaturated fatty acids and degree of unsaturated fatty acid. Moreover, the Thompson seedless grape treated with rapid dehydration resulted in a lower rate of superoxide anion production, hydrogen peroxide content, membrane permeability, and malondialdehyde content. These findings demonstrate that rapid dehydration inhibiting the browning of Thompson seedless grapes might be due to the inhibiting activities of LOX and the lower accumulation of reactive oxygen species. These activities can inhibit lipid peroxidation and slow the decomposition of unsaturated fatty acid in the membrane in Thompson seedless grapes, protecting the cellular membrane structural integrity which may result in less contact of polyphenol oxidase with phenolic substrates and less enzymatic browning during drying. The results provide a theoretical basis for the application of rapid dehydration in drying Thompson seedless grapes.

Cellular Responses Required for Oxidative Stress Tolerance of the Necrotrophic Fungus Alternaria alternata, Causal Agent of Pear Black Spot

To establish successful infections in host plants, pathogenic fungi must sense and respond to an array of stresses, such as oxidative stress. In this study, we systematically analyzed the effects of 30 mM H₂O₂ treatment on reactive oxygen species (ROS) metabolism in Alternaria alternata. Results showed that 30 mM H₂O₂ treatment lead to increased O²⁻ generation rate and H₂O₂ content, and simultaneously, increased the activities and transcript levels of NADPH oxidase (NOX). The activities and gene expression levels of enzymes related with ascorbic acid-glutathione cycle (AsA-GSH cycle) and thioredoxin systems, including superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), ascorbate peroxidase (AXP) and thioredoxin (TrxR), were remarkably enhanced by 30 mM H₂O₂ stress treatment. Additionally, 30 mM H₂O₂ treatment decreased the glutathione (GSH) content, whereas it increased the amount of oxidized glutathione (GSSG), dehydroascorbate (DHA) and ascorbic acid (AsA). These results revealed that cellular responses are required for oxidative stress tolerance of the necrotrophic fungus A. alternata.

ε-Poly-l-Lysine Enhances Fruit Disease Resistance in Postharvest Longans (Dimocarpus longan Lour.) by Modulating Energy Status and ATPase Activity

ε-poly-l-lysine (ε-PL) holds a strong antibacterial property and is widely used for food preservation. However, the application of ε-PL to enhance fruit disease resistance in postharvest longans (Dimocarpus longan Lour.) has not been explored. The objective of this study was to explore the impact of ε-PL treatment on disease occurrence and energy metabolism of longans infected with Phomopsis longanae Chi (P. longanae). It was found that, in comparison with P. longanae-inoculated longans, ε-PL could decrease the fruit disease index and adenosine monophosphate (AMP) content, increase the amounts of adenosine triphosphate (ATP), adenosine diphosphate (ADP), and energy charge, and enhance the activities of adenosine triphosphatase (ATPase) (such as H⁺-, Mg²⁺-, and Ca²⁺-ATPase) in the mitochondria, protoplasm, and vacuole. The results suggest that the higher levels of ATPase activity and energy status played essential roles in disease resistance of postharvest longan fruit. Therefore, the ε-PL treatment can be used as a safe and efficient postharvest method to inhibit the disease occurrence of longan fruit during storage at room temperature.

Impacts of exogenous ROS scavenger ascorbic acid on the storability and quality attributes of fresh longan fruit

The impacts of reactive oxygen species (ROS) scavenger ascorbic acid (AsA) treatment on the storability and quality attributes of 'Fuyan' longan fruit were explored. Compared to control samples, the treatment of 4 g L^-1 AsA solution clearly reduced fruit weight loss, indexes of fruit disease and pericarp browning, retained higher percentage of commercially acceptable fruit, higher values of chromaticity a^∗, chromaticity b^∗ , and chromaticity L^∗ , delayed pigment degradation in longan pericarp, and retarded the decreases of nutritive ingredients in longan pulp. When stored for 6 d, vitamin C (0.08 g kg^-1), sucrose (20.70 g kg^-1), total soluble sugar (56.32 g kg^-1), and total soluble solids (12.4%) in AsA-treated fruit displayed the clearly higher contents than those in control samples. These data suggested that the treatment of exogenous ROS scavenger AsA could effectively enhance the quality attributes and storability of postharvest longan fruit, thereby lengthen their postharvest shelf-life.

Influence of hydrogen peroxide on the ROS metabolism and its relationship to pulp breakdown of fresh longan during storage

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H₂O₂ down-regulated expression of ROS scavenging-related genes in longan pulp.

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H₂O₂ reduced activities of ROS scavenging enzymes (SOD, CAT, APX) in longan pulp.

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H₂O₂ reduced ROS scavenging capacity and raised O₂^–. generation rate in longan pulp.

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H₂O₂ promoted lipid peroxidation of cell membrane in pulp of harvested longan fruit.

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H₂O₂-reduced ROS scavenging capacity led to H₂O₂-stimulated pulp breakdown of longans.

The influence of hydrogen peroxide (H₂O₂) on the ROS metabolism and its relationship to pulp breakdown of fresh longan cv. Fuyan during storage was evaluated. Contrasted to control fruit, H₂O₂-treated samples manifested a higher index of pulp breakdown, an enhanced rate of O₂^–. generation, and an increased amount of MDA, but lower APX, CAT and SOD activities, reduced expressions of DlAPX, DlCAT and DlSOD, and lower concentrations of total phenolics, flavonoid, AsA, and GSH as well as lower levels of free radicals scavenging capacity. These data revealed that H₂O₂-induced pulp breakdown of longan was because H₂O₂ reduced ability of removing ROS but increased ROS generation and accumulation, which promoted peroxidation of cell membrane lipid, and subsequently led to damaging cell membrane structure and breakdown occurrence in pulp of postharvest fresh longan.

The joint toxicity of polyethylene microplastic and phenanthrene to wheat seedlings

Due to wide distribution, easy production, and difficult degradation, microplastic pollution has become a new environmental problem that has attracted worldwide attention. However, there is little information about the effects of microplastics in soil and their combined pollution with other organic pollutants on crop growth. In this study, we conducted soil culture experiments to evaluate the effects of polyethylene microplastics (PE-MPs) (0.5%, 1%, 2%, 5%, 8% w/w) individual and combined with phenanthrene (100 mg kg^-1) on wheat growth for 15 days. Under PE-MPs alone and combined with phenanthrene exposure, dose-dependent toxicities in biomass, shoot height and root length were observed. Over 1% PE-MPs stimulate wheat root elongation. Compared with single phenanthrene treatment, the co-contamination of PE-MPs and phenanthrene reduces the accumulation of phenanthrene in wheat roots and leaves. In the range of 0-5%, the activity of wheat root antioxidant enzymes increases with increasing PE-MP concentration; but both phenanthrene and high concentrations (8%) of PE-MPs cause damage to the antioxidant system in wheat roots. In the presence or absence of phenanthrene, the photosynthetic pigment concentration of wheat leaves shows a dual concentration effect of low promotion and high inhibition under PE-MPs stress. The single pollution of PE-MPs destroys the photosynthetic system of wheat leaves, while the co-contamination of PE-MPs and phenanthrene exacerbates this destruction. Therefore, the co-contamination of PE-MPs and phenanthrene causes greater damage to wheat growth. Our findings can help to evaluate the individual and comprehensive toxicity of microplastics and polycyclic aromatic hydrocarbons to crops.

Heat shock treatment maintains the quality attributes of postharvest jujube fruits and delays their senescence process during cold storage

The effects of heat shock (HT), 1-methylcyclopropene (1-MCP), or their combination (HT + 1-MCP) on the quality of fresh jujube fruits during cold storage were studied. Among them, HT showed the best preservation effect on jujube fruits, which was more effective than others in inhibiting the increase of red index, decay incidence, and weight loss and delaying the decrease of firmness, soluble solids content (SSC), titratable acidity (TA), and ascorbic acid (AsA) content. Besides, it could delay the degradation rate of the cell wall to maintain the integrity of cell membrane, and keep the high activity of active oxygen scavenging enzymes. During cold storage, malondialdehyde (MDA) content and relative electrolyte leakage (REL) of the HT group were significantly lower than those of the control group, 1-MCP, and HT + 1-MCP group (p < .05), while superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities were significantly higher than those of other groups (p < .05). It was concluded that the postharvest HT treatment could effectively delay the senescence and decay of jujube fruits. PRACTICAL APPLICATIONS: Jujube fruits have high nutritional value used for food and medicine. However, they are not tolerant to storage after harvest, resulting in high economic losses. Therefore, it is of great significance to find a suitable method to maintain the quality of jujube fruits. Our results revealed the effect of HT, 1-MCP, and their combination on the quality maintenance of jujube fruits, and found that HT could effectively maintain the quality of them, which could be used as an effective method for keeping jujube fruits fresh.

The role of cell wall polysaccharides disassembly in Lasiodiplodia theobromae-induced disease occurrence and softening of fresh longan fruit

Cell wall polysaccharides in fruits act a pivotal role in their resistance to fungal invasion. Lasiodiplodia theobromae (Pat.) Griff. & Maubl. is a primary pathogenic fungus causing the spoilage of fresh longan fruit. In this study, the influences of L. theobromae inoculation on the disassembly of cell wall polysaccharides in pericarp of fresh longans and its association with L. theobromae-induced disease and softening development were investigated. In contrast to the control, samples with L. theobromae infection showed more severe disease development, lower firmness, lower amounts of cell wall materials, covalent-soluble pectin, ionic-soluble pectin, cellulose and hemicellulose, whereas higher value of water-soluble pectin, higher activities of cell wall polysaccharide-disassembling enzymes (cellulase, β-galactosidase, polygalacturonase and pectinesterase). These findings revealed that cell wall polysaccharides disassembly induced by enzymatic manipulation was an essential pathway for L. theobromae to infect harvested longans, and thus led to the disease occurrence and fruit softening.

Boletus aereus protects against acute alcohol-induced liver damage in the C57BL/6 mouse via regulating the oxidative stress-mediated NF-κB pathway

CONTEXT

Alcoholic liver disease, caused by abuse and consumption of alcohol, exhibits high morbidity and mortality. Boletus aereus Bull. (Boletaceae) (BA) shows antioxidant, anti-inflammatory and antimicrobial effects.

OBJECTIVES

To investigate the hepatoprotective effects of BA using an acute alcohol-induced hepatotoxicity mice model.

MATERIALS AND METHODS

The composition of BA fruit body was first systematically analyzed. Subsequently, a C57BL/6 mice model of acute alcohol-induced liver injury was established by intragastrically administration of alcohol, which was intragastrically received with BA powder at 200 mg/kg and 800 mg/kg for 2 weeks, 60 mg/kg silybin treatment was used as positive control group. By employing the pathological examination, ELISA, RT-PCR and western blot, the regulation of BA on oxidative stress signals was investigated.

RESULTS

The LD₅₀ of BA was much higher than 4 g/kg/p.o. In acute alcohol-damaged mice, BA reduced the levels of alanine aminotransferase (>18.3%) and aspartate aminotransferase (>27.6%) in liver, increased the activity of liver alcohol dehydrogenase (>35.0%) and serum acetaldehyde dehydrogenase (>18.9%). BA increased the activity of superoxide dismutase (>13.4%), glutathione peroxidase (>11.0%) and 800 mg/kg BA strongly reduced chemokine (C-X-C motif) ligand 13 (14.9%) and chitinase-3 like-1 protein (13.4%) in serum. BA reversed mRNA over-expression (>70%) and phosphor-stimulated expression (>45.0%) of an inhibitor of nuclear factor κ-B kinase (NF-κB, an inhibitor of nuclear factor κ-B α and nuclear factor κ-B in the liver.

CONCLUSIONS

BA is effective in ameliorating alcohol-induced liver injury through regulating oxidative stress-mediated NF-κB signalling, which provides a scientific basis for further research on its clinical applications.

Exogenous Melatonin Attenuates Post-Harvest Decay by Increasing Antioxidant Activity in Wax Apple (Syzygium samarangense)

Wax apple is one of the most popular tropical fruit but undergoes serious post-harvest decay during storage, transportation and marketing. Melatonin (MT) plays important roles in plant growth, development and stress responses. However, its function in post-harvest preservation of fruit remains largely unknown. In the present study, the physiological function and molecular mechanism of exogenous MT for post-harvest preservation were evaluated in wax apple fruit. Results showed that MT treatment remarkably reduced decay incidence and the accumulation of excess reactive oxygen species (ROS) but increased the activity of antioxidant enzymes, suggesting that exogenous MT alleviates the post-harvest decay of wax apple by regulating the balance between ROS production and antioxidant system. Meanwhile, the gene expression was analyzed by transcriptome confirmed by quantitative PCR. This study provides insights into the regulatory mechanism and proper application strategies for post-harvest preservation of wax apple and other fruits though melatonin manipulation.

PuMYB21/PuMYB54 coordinate to activate PuPLDβ1 transcription during peel browning of cold-stored "Nanguo" pears

Refrigeration is commonly used to extend the storage life of "Nanguo" pears, but fruit in long-term refrigeration is prone to peel browning, which is related to membrane lipid degradation. To determine the mechanism of membrane lipid degradation, we identified two R2R3-MYB transcription factors (TFs), PuMYB21 and PuMYB54, from "Nanguo" pears, which were notably expressed in response to cold stress and during the peel-browning process. The results from yeast one-hybrid, electrophoretic mobility shift, and transient expression assays indicated that both PuMYB21 and PuMYB54 directly bind to the promoter of PuPLDβ1 (a key enzyme catalyzing the hydrolysis of membrane phospholipids) and activate its expression, which probably enhances the degradation of membrane phospholipids and eventually results in peel browning. Moreover, the overexpression of PuMYB21 and PuMYB54 can greatly activate the transcription of endogenous PuPLDβ1 in both "Nanguo" pear fruits and calli, and their silencing can inhibit its transcription. Furthermore, yeast two-hybrid, bimolecular fluorescence complementation, and pull-down assays verified that PuMYB21 interacts with PuMYB54 to enhance the expression of PuPLDβ1. In summary, we demonstrate that PuMYB21 and PuMYB54 may have roles in membrane lipid metabolism by directly binding to the downstream structural gene PuPLDβ1 during the low temperature-induced peel browning of "Nanguo" pears.

Inhibition of fruit softening by cold plasma treatments: affecting factors and applications

Softening is a common phenomenon of texture changes associated with plant cell walls, inducing a decrease in the quality of fruit. Inhibiting the softening is effective to extend the shelf life of fruit. Cold plasma (CP), as a novel nonthermal technology, has been applied to keep the freshness of the fruit. This review centers on applying cold plasma treatments to the inhibition of fruit softening. Different pathways for inhibiting fruit softening by CP treatments, including maintenance of fruit firmness, reduction in the activities of enzymes, inactivation of fungal pathogens and lowering of respiration rates, are discussed. The biochemistry of fruit softening and the fundamental of cold plasma are also presented. In general, among all postharvest technologies, cold plasma is a promising method with many advantages, showing great potential in maintaining the quality and inhibiting the softening of the fruit. Future work should focus on process optimization to achieve better results in maintaining fruit freshness, and commercial applications of cold plasma technology should also be explored.

Effects of acidic electrolyzed water treatment on storability, quality attributes and nutritive properties of longan fruit during storage

The aim of this study was to use acidic electrolyzed water (AEW) to treat longan fruit and evaluate the effects of AEW treatment on storability, quality attributes and nutritive properties of longans during storage. The data indicated that, as compared to the control samples, AEW treatment could effectively reduce the respiration rate and pericarp cell membrane permeability, retard the occurrences of pericarp browning, pulp breakdown and fruit disease, keep a higher rate of commercially acceptable fruit. Additionally, AEW treatment could suppress the decrease of chromaticity values of L*, a* and b* of the fruit surface, keep higher amounts of pericarp carotenoid, chlorophyll, flavonoid and anthocyanin, maintain higher amounts of pulp total soluble solid (TSS), total soluble sugars, sucrose and vitamin C. These results demonstrated that AEW treatment at pH of 2.5, ACC of 80 mg/L could maintain higher quality attributes and nutritive properties, and display better storability of harvested longans.