Activity Of Cell Wall-degrading Enzymes Research Articles

Metal-organic frameworks-based moisture responsive essential oil hydrogel beads for fresh-cut pineapple preservation

The preservation of fresh-cut fruits and vegetables has attracted attention to the shelf-life reduction caused by high humidity. Herein, alginate/copper ions cross-linking, in-situ growth and self-assembly techniques of metal-organic frameworks (MOFs) were utilized to prepare a moisture responsive hydrogel bead (HKUST-1@ALG). As the multistage porous structure formation, tea tree essential oil (TTO) load capacity in hydrogel bead (TTO-HKUST-1@ALG) was increased from 6.1% to 21.6%. TTO-HKUST-1@ALG had excellent moisture response performance, and the release rates of TTO increased from 33.89% to 70.98% with moisture increasing from 45% to 95%. Besides, TTO-HKUST-1@ALG exhibited excellent antimicrobial, antioxidant capacity, and biocompatibility. During storage, TTO-HKUST-1@ALG effectively improved the cell membrane integrity by maintaining the balance of reactive oxygen species metabolism. The degradation of cell wall structure and tissue softening were delayed by inhibiting the cell wall-degrading enzymes activity. Briefly, TTO-HKUST-1@ALG improved the storage quality and extended shelf-life of fresh-cut pineapple, which was a promising preservative.

Exogenous CaCl2 delays flesh softening by inhibiting the degradation of cell wall in fresh-cut cantaloupe

Flesh softening is closely related to the quality of postharvest produces. Although the use of calcium chloride (CaCl2) has been shown to inhibit fruit softening, the underlying molecular mechanisms have remained unclear. In our present investigation, CaCl2 treatment resulted in an enhancement of cytosolic free Ca2+ and polysaccharide contents, firmness, and the integrity of the cell wall structure, particularly evident in the denser middle lamella of fresh-cut cantaloupe. CaCl2 treatment also inhibited the cell wall degrading enzyme activities and gene expressions. Moreover, CmCAMTA2 could identify and bind to the CG-box structure of CmCellulase, Cmα-Gal3, and Cmβ-Glu12, thereby suppressing their transcription. In conclusion, current findings illustrated that CaCl2 treatment triggered CmCAMTA2-mediated transcriptional suppression on cell wall degrading genes, inhibited the polysaccharide component degradation, and maintained better structure integrity of the cell wall, thereby delaying the flesh softening of fresh-cut cantaloupe.

A novel polyethylene nanopackaging combined with ozone fumigation delayed the browning and softening of Agaricus bisporus during postharvest storage

To elucidate the effect and mechanism of a novel polyethylene nanopackaging combined with ozone fumigation (O3 +NA) on delaying browning and softening of Agaricus bisporus during postharvest storage, quality changes under different treatments at low temperature over 18 d in storage were analyzed at the sensory, physiological and biochemical levels. It showed that, compared with ozone fumigation (O3), commercial polyethylene packaging (PE) and no packaging, O3 +NA improved the storage quality of mushrooms mainly by reducing the browning index, while maintaining firmness and whiteness. In comparison to the control group, O3 +NA increased the activities of antioxidant enzymes and reduced the accumulation of reactive oxygen species (ROS), thus maintaining the better antioxidant activity of A. bisporus. This combined treatment not only inhibited the activity of enzymes related to browning but also maintained low levels of cell wall degrading enzymes activity, which restricted the softening of A. bisporus during storage. Therefore, O3 +NA improved the storage quality of mushrooms. Compared with conventional commercial PE film packaging, O3 +NA prolonged the shelf-life of mushroom at low temperature by 6–9 d, providing an effective composite preservation technology.

Effects of Near-Freezing Temperature Combined with Jujube Polysaccharides Treatment on Proteomic Analysis of 'Diaogan' Apricot (Prunus armeniaca L.).

This study involved the extraction of polysaccharides from jujube for application in apricot storage. Although near-freezing temperature (NFT) storage is commonly employed for preserving fresh fruit, its effectiveness is somewhat limited. Incorporating jujube polysaccharides was proposed to augment the preservative effect on apricots. Our findings demonstrated that the combined use of NFT and jujube polysaccharides can maintain fruit color, and effectively inhibit decay. Additionally, Tandem Mass Tag (TMT) quantitative proteomic technology was utilized to analyze protein variations in 'Diaogan' apricots during storage. This dual approach not only markedly lowered the activity of polyphenol cell wall-degrading enzymes (p < 0.05) but also revealed 1054 differentially expressed proteins (DEPs), which are related to sugar and energy metabolism, stress response and defense, lipid metabolism, and cell wall degradation. The changes in DEPs indicated that the combined use of NFT and jujube polysaccharides could accelerate the conversion of malic acid to oxaloacetic acid and regulate antioxidant ability, potentially extending the storage lifespan of apricot fruit.

Construction of photocatalytic coating for alleviating the shriveling of postharvest fruit cucumber after simulated transportation

The shriveling of fruit cucumber was commonly occurred during supply chain, photocatalyst exposed to UV light can endow the coatings with ethylene removal capacity to reduce the respiration of fruit and water loss. The study developed a novel photodynamic technology responsive photocatalytic coating with exceptional ultraviolet (UV) photocatalytic degradation of ethylene ability to decay the shriveling of postharvest fruit cucumber during supply chain. This coating involved the integration of Carbon dots (CDs)-loaded nano ZnO and the skillful selection of pullulan (Pul) and apple pectin (AP) matrix. The CDs/ZnO coatings boasted an impressive array of photocatalytic degradation of ethylene and adhesion properties, including high ethylene removal rates of 32.04 % in 60 min UV light stimulation. The decrease of cell-wall strength, degradation of the cell wall polysaccharides and water loss resulted in cucumber shriveling. Compared with CK sample, after UV-CDs/ZnO coating treatment, the higher firmness and cell wall polysaccharides were found in cucumbers with lower cell wall degrading enzymes activities, weight loss and water movement, which was associated with the decrease of respiration and ethylene accumulation. The UV-CDs/ZnO coatings possessed promising potential for alleviating the shriveling of postharvest fruit cucumber and applications in fruits preservation in the future.

Analysis of Aureobasidium pullulans LB83 secretome reveals distinct carbohydrate active enzymes for biomass saccharification

Aureobasidium pullulans LB83 is a versatile biocatalyst that produces a plethora of bioactive products thriving on a variety of feedstocks under the varying culture conditions. In our last study using this microorganism, we found cellulase activity (FPase, 2.27 U/ml; CMCase, 7.42 U/ml) and other plant cell wall degrading enzyme activities grown on sugarcane bagasse and soybean meal as carbon source and nitrogen, respectively. In the present study, we provide insights on the secretome analysis of this enzymatic cocktail. The secretome analysis of A. pullulans LB83 by Liquid Chromatography coupled to Mass Spectroscopy (LC-MS/MS) revealed 38 classes of Carbohydrate Active enZymes (CAZymes) of a total of 464 identified proteins. These CAZymes consisted of 21 glycoside hydrolases (55.26%), 12 glycoside hydrolases harboring carbohydrate-binding module (31.58%), 4 carbohydrate esterases (10.53%) and one glycosyl transferase (2.63%). To the best of our knowledge, this is the first report on the secretome analysis of A. pullulans LB83.

Increased weight loss and internal air space, degraded starch and pectin combined to cause pulp mealiness in ‘Oregon Spur Ⅱ’ apples during ambient storage

Pulp mealiness is a common phenomenon in ‘Delicious’ apples during ambient storage, but the underlying mechanism remains poorly understood. In the present study, fruit physiological and quality parameters, the volume of internal air space and the degree of mealiness as well as cell wall-degrading enzyme activities and pectin material content were measured in ‘Oregon Spur Ⅱ’ apple fruit during ambient storage. The results showed that the peaks of respiration rate and ethylene production of ‘Oregon Spur Ⅱ’ fruit occurred at 5 d and 10 d of storage, respectively, during which the starch and malic acid contents and firmness decreased significantly, while the fruit weight loss, the volume of internal air space and the degree of mealiness increased rapidly. Meanwhile, the activities of pectin methylesterase (PME) and pectin lyase (PL) showed a unimodal change during storage, whereas the activity of polygalacturonase (PG) decreased, and the activities of α-L-arabinofuranosidase (α-AFase) and β-galactosidase (β-Gase) as well as the contents of water-soluble pectin (WSP), chelator-soluble pectin (CSP), and sodium carbonate-soluble pectin (NSP) increased with increasing storage time. Correlation analysis showed that α-AFase, β-Gase, WSP, CSP, weight loss, the volume the air space, firmness, starch, and malic acid were significantly correlated with the degree of pulp mealiness (|r|>0.9). In conclusion, increased weight loss and internal air space, degraded starch and pectin combined to cause pulp mealiness in ‘Oregon Spur Ⅱ’ apples during ambient storage.

Biochemistry behind firmness retention of jujube fruit by combined treatment of acidic electrolyzed water and high-voltage electrostatic field.

Harvested jujube (Zizyphus jujuba Mill) is prone to softening due to active metabolism. This study investigated the effects of acidic electrolyzed water (AEW), high-voltage electrostatic field (HVEF) and their combination (AEW+HVEF) on softening and associated cell wall degrading enzymes (CWDEs), cell membrane integrity and antioxidant system of 'Huping' jujube during storage at 0±1°C. The results indicated that fruit subjected to AEW+HVEF, AEW or HVEF treatments maintained firmness 15.7%, 10.7%, and 5.3% higher than that of untreated control fruit at the end of 90days cool storage. Fruit treated with AEW+HVEF could better maintain cell membrane integrity and exhibit lower activities of CWDEs and higher antioxidant capacity than that treated with either AEW or HVEF. Correlation analysis suggested that inhibition of softening was associated with reduction of CWDEs activities, and maintenance of membrane integrity and antioxidant system.

Biological control potential of a soil fungus Trichoderma asperellum K1-02 against Neoscytalidium dimidiatum causing stem canker of dragon fruit

Stem canker on dragon fruit caused by the fungus Neoscytalidium dimidiatum negatively impact dragon fruit cultivation and production. The use of Trichoderma species, the biological control agent against stem canker disease is an alternative way instead of use of synthetic fungicides. This study aimed to test the antifungal activities of soil fungi Trichoderma against N. dimidiatum. Ten isolates of Trichoderma species were tested against N. dimidiatum via dual culture assay, and the results showed that percentages of inhibition ranged from 72.75 to 84.45%. Trichoderma species K1-02 was found to be the most effective strain against N. dimidiatum (84.45%). Trichoderma K1-02 was identified based on a morphology and molecular study of internal transcribed spacer (ITS), the second largest subunit of RNA polymerase II (rbp2), and the translation elongation factor 1-alpha (tef1-α) as Trichoderma asperellum K1-02. The pre-colonized plate method demonstrated that T. asperellum K1-02 covered the tested plates at a rate of 60%, which was significantly higher than N. dimidiatum (40%), and T. asperellum K1-02 aggressively covered the mycelia of N. dimidiatum as observed via stereomicroscopy. An enzyme assay was conducted to test the activities of cell wall-degrading enzymes (CWDEs) in cell-free culture filtrate (CF) released by T. asperellum K1-02, and the results showed that the activities of chitinase and β-1,3-glucanase were significantly higher than those of the control (potato dextrose broth alone). Scanning electron microscopy of N. dimidiatum mycelia incubated with cell free CF of T. asperellum K1-02 showed abnormal morphology. Furthermore, an in vivo test was conducted on dragon fruit cladodes to test the ability of Trichoderma with respect to the reduction of canker lesions. The results revealed that the application of 106 spore/mL T. asperellum K1-02 spore suspension suppressed disease development via the reduction of canker areas (0.09 cm2) on dragon fruit cladodes at a significantly higher level than those inoculated by pathogens alone (0.49 cm2). Thus, T. asperellum K1-02 demonstrated antifungal abilities against N. dimidiatum and has the potential to control stem canker on dragon fruit.

Benzoic acid promotes Fusarium wilt incidence by enhancing susceptibility and reducing photosynthesis of faba bean

AbstractContinuous faba bean (Vicia faba L.) cropping causes adverse effects, including increased secretion of autotoxic substances (benzoic acid) and incidence of diseases (Fusarium wilt). Fusarium commune infects faba bean seedlings and is treated with different benzoic acid concentrations. Therefore, this investigation analysed the association of benzoic acid with faba bean wilt incidence and the mechanisms involved. Furthermore, seedling growth, tissue structure, Fusarium wilt incidence, cell wall degrading enzymes (CWDEs) activity, lignin levels, and leaf photosynthetic parameters were assessed. The results indicated that fungal infection markedly reduced biomass and photosynthesis in the faba bean. Microscopic analysis showed slightly thickened stems' xylem vessels. Benzoic acid treatment with F. commune infection substantially increased F. commune‐mediated CWDEs activity in the faba bean stem and lignin level but reduced photosynthesis and biomass, elevating Fusarium wilt incidence. Furthermore, broken tissues, xylem thickening, and stem cavities were observed. The investigation indicated that benzoic acid treatment and F. commune infection‐induced stem lignin might be a resistance response; however, increased pathogenicity and reduced photosynthesis enhanced susceptibility and aggravated Fusarium wilt.

Electrostatic Atomized Water Particles Induce Disease Resistance in Muskmelon (Cucumis melo L.) against Postharvest Fruit Rot Caused by Fusarium incarnatum.

The postharvest quality of muskmelon can be affected by fruit rot caused by the fungus Fusarium incarnatum, resulting in loss of quality. The utilization of electrostatic atomized water particles (EAWPs) in agriculture applications has been shown to induce disease resistance in plants. Therefore, in this study, we determined the effect of electrostatic atomized water particles (EAWPs) on the disease resistance of muskmelon fruits against postharvest fruit rot caused by F. incarnatum. EAWPs were applied to muskmelon fruits for 0, 30, 60, and 90 min. EAWP-treated muskmelon fruits were inoculated with F. incarnatum, and disease progress was measured. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) of the chitinase (CmCHI) and β-1,3-glucanase (CmGLU) genes of Cucumis melo (muskmelon) was performed for EAWP-treated and -untreated muskmelon fruits. The activities of cell-wall-degrading enzymes (CWDEs), chitinase, and β-1,3-glucanase were also assayed in EAWP-treated and -untreated muskmelon fruits. The results showed that disease progress was limited by EAWP treatment for 30 min prior to pathogen inoculation. Muskmelon fruits treated with EAWPs for 30 min showed an upregulation of CWDE genes, CmCHI and CmGLU, as observed by qRT-PCR, leading to high chitinase and β-1,3-glucanase activities, as observed through enzyme assays. The results of SEM microscopy revealed that the effect of the crude enzymes of EAWP-treated muskmelon caused morphological changes in F. incarnatum mycelia. Furthermore, treatment with EAWPs preserved postharvest quality in muskmelon, including with regard to texture stiffness and total chlorophyll contents, compared to untreated muskmelon. These results demonstrate that the pretreatment of muskmelon with EAWPs suppresses the development of F. incarnatum in the early stage of infection by regulating gene expression of CWDEs and elevating the activities of CWDEs, while also maintaining postharvest muskmelon quality.

Postharvest Calcium Chloride Treatment Strengthens Cell Wall Structure to Maintain Litchi Fruit Quality.

Litchi (Litchi chinensis Sonn.) fruit deterioration occurs rapidly after harvest and is characterized by pericarp browning, pulp softening, and decay. In this study, we found that calcium chloride (CaCl2) treatment (5 g L-1 CaCl2 solution vacuum infiltration for 5 min) affected the cell wall component contents and cell wall-degrading enzyme activities of litchi fruit during storage at room temperature. CaCl2 treatment significantly increased the contents of Ca2+ and cellulose, while it decreased the water-soluble pectin content, and the activities of polygalacturonase, β-galactosidase, and cellulase in the litchi pericarp. Meanwhile, the treatment resulted in significantly increased contents of Ca2+, water-soluble pectin, ionic-soluble pectin, covalent-soluble pectin and hemicellulose, and upregulated activities of pectinesterase and β-galactosidase, while significantly decreasing the activities of polygalacturonase and cellulase in litchi pulp. The above results indicate that CaCl2 treatment strengthened the cell wall structure of litchi fruit. More importantly, the enzymatic browning of the pericarp, softening of the pulp, and disease incidence were delayed. The treatment had a more pronounced effect on the pericarp than on the pulp. We consider CaCl2 treatment to be a safe and effective treatment for maintaining the postharvest quality of litchi fruit.

Transcriptomic and metabolomic analyses reveal molecular mechanisms associated with the natural abscission of blue honeysuckle (Lonicera caerulea L.) ripe fruits

Blue honeysuckle (Lonicera caerulea L.) is rich in phenolic compounds and has an extremely high nutritional value. Fruit abscission in the ripe period significantly impacts production and economic benefits. However, the mechanism associated with the abscission of blue honeysuckle fruit remains largely unknown. The easy-abscission cultivar ‘HSY’ and the hard-abscission cultivar ‘Berel’ were selected as plant materials. Anatomical changes of the ‘HSY’ fruit abscission zone (FAZ) during the abscission mainly included cell expansion, detachment, and collapse. Active changes in cell wall-degrading enzyme activity between 39 days postanthesis (DPA) and 55 DPA in ‘HSY’ FAZ, but not in ‘Berel’, suggest a critical role for cell-wall-degrading enzymes in regulating abscission. Transcriptome and metabolome analyses revealed that the genes and metabolites responding to abscission mainly act on pathways such as plant hormone signal transduction, starch and sucrose metabolism, pentose and glucuronate interconversions, and phenylpropanoid biosynthesis. The regulatory pathways of fruit abscission are mainly summarized into two parts: phytohormone synthesis and signal transduction, FAZ cell wall metabolism. In this study, 46 key genes related to plant hormone response, 45 key genes involved in FAZ cell wall metabolism, and 73 transcription factors were screened. Quantitative real-time PCR (qRT-PCR) assessed the expression pattern of 12 selected candidate genes, demonstrating the accuracy of the transcriptome data and elucidating the expression patterns of key candidate genes during growth and development. This study will provide an essential resource for understanding the molecular regulatory mechanism of fruit abscission in the blue honeysuckle.

Isolation and identification of mycorrhizal helper bacteria of Vaccinium uliginosum and their interaction with mycorrhizal fungi.

Mycorrhizal helper bacteria (MHB) can promote mycorrhizal fungal colonization and form mycorrhizal symbiosis structures. To investigate the effect of interactions between mycorrhizal beneficial microorganisms on the growth of blueberry, 45 strains of bacteria isolated from the rhizosphere soil of Vaccinium uliginosum were screened for potential MHB strains using the dry-plate confrontation assay and the bacterial extracellular metabolite promotion method. The results showed that the growth rate of mycelium of Oidiodendron maius 143, an ericoid mycorrhizal fungal strain, was increased by 33.33 and 77.77% for bacterial strains L6 and LM3, respectively, compared with the control in the dry-plate confrontation assay. In addition, the extracellular metabolites of L6 and LM3 significantly promoted the growth of O. maius 143 mycelium with an average growth rate of 40.9 and 57.1%, respectively, the cell wall-degrading enzyme activities and genes of O. maius 143 was significantly increased. Therefore, L6 and LM3 were preliminarily identified as potential MHB strains. In addition, the co-inoculated treatments significantly increased blueberry growth; increased the nitrate reductase, glutamate dehydrogenase, glutamine synthetase, and glutamate synthase activities in the leaves; and promoted nutrient uptake in blueberry. Based on the physiological, and 16S rDNA gene molecular analyses, we initially identified strain L6 as Paenarthrobacter nicotinovorans and LM3 as Bacillus circulans. Metabolomic analysis revealed that mycelial exudates contain large amounts of sugars, organic acids and amino acids, which can be used as substrates to stimulate the growth of MHB. In conclusion, L6 and LM3 and O. maius 143 promote each other's growth, while co-inoculation of L6 and LM3 with O. maius 143 can promote the growth of blueberry seedlings, providing a theoretical basis for further studies on the mechanism of ericoid mycorrhizal fungi-MHB-blueberry interactions. It laid the technical foundation for the exploitation of biocontrol strain resources and the development of biological fertilizer.

Transcriptome analysis reveals key metabolic pathways and gene expression involving in cell wall polysaccharides-disassembling and postharvest fruit softening in custard apple (Annona squamosa L.)

This study aimed to investigate the effect of custard apple cell wall polysaccharides-disassembling on postharvest fruit softening and to explore its key metabolic pathways and gene expression. Custard apple fruit was stored at 15 ± 0.5 °C for 12 days, it was found that the decreased significantly in fruit firmness, contents of Na2CO3-soluble pectin, hemicellulose and cellulose, and the increased significantly in water-soluble pectin and CDTA-soluble pectin. The activities of cell wall-degrading relevant enzymes in fruit were improved significantly during storage, including cellulase, polygalacturonase, pectin methyl esterase, neutral xylanase, β-galactosidase, and β-D-glucosidase. The RNA sequencing results revealed 41,545 nonredundant unigenes and 7571 differentially expressed genes (DEGs) in custard apple fruit samples. Functional annotation and DEGs data revealed cell wall degradation potentially involved in starch and sucrose metabolism, amino sugar and nucleotide sugar metabolism, galactose metabolism, pentose and glucuronate interconversions. Specifically, two EG and six β-Glc genes controlled the cellulose decomposition, and one β-xyl and one GATU genes involved in the degradation of hemicellulose, and two PME, one Pel, and four PG genes were the major regulators of pectin disassembling. These results provide a molecular foundation for explaining fruit softening and extending shelf life of custard apple.

Wheat–faba bean intercropping can control Fusarium wilt in faba bean under F. commune and ferulic acid stress as revealed by histopathological analysis

Fusarium wilt, is an important soilborne disease restricting the cultivation of faba bean. Wheat–faba bean intercropping is one of the useful means to control Fusarium wilt in faba bean. In this study, we analyzed the histopathological effect of wheat–faba bean intercropping system on Fusarium wilt in faba bean under F. commune and ferulic acid stress. Faba bean was inoculated with F. commune. Various concentrations of ferulic acid were added to the inoculated plants to study the occurrence of Fusarium wilt, growth of faba bean seedlings, activity of cell-wall-degrading enzymes (CWDEs) produced by F. commune in stems, and structural changes in stem tissues under monocropping and intercropping systems. When ferulic acid was added to the faba bean plants inoculated with F. commune, wheat–faba bean intercropping significantly reduced the activity of CWDEs. Microstructure observation revealed that the xylem vessel was thickened, and xylem parenchymal tissue and vascular cambium produced gelatinous substance and tylose. Moreover, callose deposition was reduced in the sieve tube; death rate of vascular tissue, cortex tissue, and epidermis tissue was reduced, and faba bean biomass was observably increased. The combination of these factors reduced the occurrence of Fusarium wilt. Therefore, wheat–faba bean intercropping reduced the severity of Fusarium wilt in faba bean by decreasing the activities of CWDEs and increasing tissue structure integrity.

Regulation of Cell Wall Degradation and Energy Metabolism for Maintaining Shelf Quality of Blueberry by Short-Term 1-Methylcyclopropene Treatment

In order to study a short-term and efficient technology by 1-methylcyclopropene (1-MCP) in blueberry, the fruit was treated with 0, 0.5, 1 and 3 μL/L 1-MCP for 2 h then stored at 25 ± 1 °C with 40–50% relative humidity (RH) for 9 d. The weight loss, decay incidence, respiration rate, firmness, soluble solid content (SSC), titratable acid (TA), Brix-acid ratio (BAR), sensory evaluation, content of cell wall polysaccharide, activities of cell wall composition-related enzymes and energy metabolism in blueberry were determined during shelf life. The results showed that the weight loss, decay incidence and respiration rate were reduced by 3 μL/L 1-MCP treatment. Compared to other groups, the firmness, the content of TA and anthocyanins were maintained in 3 μL/L 1-MCP-treated blueberry. In contrast, the SSC and BAR were lower compared to those untreated. However, the sensory evaluation of “taste” and “aroma” value showed no differences in all fruits. The content of protopectin, cellulose and hemicellulose was higher in 1-MCP-treated blueberry, accompanied by a decrease in polygalacturonase (PG) and pectin methyl esterase (PME) activity. The content of water-soluble pectin (WSP) was lower in 1-MCP-treated blueberry than untreated ones. The activity of phenylalanine ammonia lyase (PAL), peroxidase (POD), cinnamyl alcohol dehydrogenase (CAD) and 4-coumarate-CoA ligase (4CL) was higher in 1-MCP-treated blueberry than the untreated, which induced more serious lignification. The results of energy metabolism also showed that the 1-MCP treatment could ensure sufficient intracellular energy supply. The 3 μL/L 1-MCP treatment could maintain the shelf quality and retard decomposition of cell wall polysaccharide by ensuring sufficient intracellular energy supply and inhibiting cell wall-degrading enzymes activity. Taken together, this study highlighted an efficient and short-term 1-MCP treatment technique.

Transcriptomics analysis reveals molecular mechanism of softening and cell wall polysaccharides-disassembling in peaches treated by flow microcirculation of sodium nitroprusside medium

Peach (Prunus persica L. Batsch. var. compressa Bean) is prone to softening during storage, and this leads to a marked deterioration in quality and shortened shelf life. The influences of sodium nitroprusside (SNP) atomization on softening development, cell wall ultrastructure, cell wall polysaccharides metabolism in peach fruit stored at 0 ± 0.5 °C for 60 d were explicated. SNP atomization treated fruit, when contrasted to the control, exhibited higher firmness, contents of chelate-soluble pectin (CSP), sodium carbonate-soluble pectin (SSP), cell wall materials (CWM), cellulose and hemicellulose (HC), but lower water-soluble pectin (WSP) content. SNP treatment suppressed activities of cell wall-degrading relevant enzymes, the disassembly of cell wall structure, and the decomposition of middle lamella and plasma membrane in peach fruit. The RNA sequencing results suggested that the differentially expressed genes from amino sugar metabolic process (beta-D-xylosidase, BXL), galactose metabolism (beta-galactosidase, β-Gal), pentose and glucuronate interconversions (polygalacturonase, PG), cellular carbohydrate metabolic process (xyloglucan- endotransglucosylase/hydrolase, XTH), and expansin (Exp) were associated with cell wall degradation in peaches with aerosolized water (control) or SNP treatments. Based on these results, the delayed softening of peaches with SNP atomization was ascribed to cell wall polysaccharides degradation regulated by gene expression levels and enzymes.

Biocontrol Ability and Action Mechanism of Meyerozyma guilliermondii 37 on Soft Rot Control of Postharvest Kiwifruit.

Postharvest soft rot of kiwifruit has resulted in substantial market losses, yet there were few antagonistic yeasts reported to control the disease. This study screened 1113 yeast strains for potential antagonistic yeast to control soft rot of kiwifruit caused by Botryosphaeria dothidea and Diaporthe&amp;nbsp;actinidiae, and strain 37 was selected to evaluate the control efficacy and mechanisms, which was identified as Meyerozyma guilliermondii via molecular biological identification. Our results showed that M. guilliermondii 37 effectively reduced pathogen spore germination rate to 28.52% and decay incidence of inoculated kiwifruit to 42.11% maximumly, whereas cell-free supernatant lacked antifungal activity, implying that M. guilliermondii 37 didn't produce direct antifungal compounds against the two pathogens. In addition, M. guilliermondii 37 adhered tenaciously to the pathogens' mycelium and colonized rapidly in kiwifruit flesh. Moreover, yeast strain 37 induced kiwifruit resistance by elevating the defense-related enzyme activity, increasing the antioxidant substances content, and suppressing the cell wall-degrading enzyme activity. Gene expression was consistent with the corresponding enzyme activity. Further postharvest yeast immersion treatment significantly reduced natural decay to 35.69% while maintaining soft-ripe quality. These results indicated that M. guilliermondii 37 might serve as a biocontrol agent against postharvest soft rot in kiwifruit.

Antifungal Activity of Ginger Rhizome Extract against Fusarium solani

Fusarium solani is one of the most ruinous soil-borne pathogens and seriously affects crop yields and quality worldwide. Ginger is an important medicinal crop, and ginger rhizome extract (GRE) has been used as an alternative for chemical fungicides and bactericides. We investigated the fungistatic effect of GRE on F. solani and analyzed the chemical constituents of GRE using UPLC-MS/MS. Antifungal assay results showed that 20 mg/mL of GRE completely inhibited the growth of F. solani. Morphological analysis revealed that GRE destroyed the morphology and structure of mycelia, thus inhibiting mycelial growth. Furthermore, GRE suppressed the activities of cell wall-degrading and cellular respiratory-related enzymes and decreased the content of fusaric acid, which reduced or even abrogated the infection ability of F. solani. UPLC-MS/MS analysis showed that GRE constituents belonged to eight categories, among which phenolic acids were the highest in content (46.29%) and tannins were the lowest in content (0.06%). When the antifungal activities of major phenolic and flavonoid compounds were evaluated, 4.0 mg/mL 4-hydroxybenzaldehyde and 15.0 mg/mL quercetin were found to completely inhibit F. solani growth. These results highlight GRE as an excellent source of antifungal compounds and suggest the possibility of using 4-hydroxybenzaldehyde and quercetin as natural fungicides to control crop diseases.