Wounding induces the accumulation of phenolic compounds in carrot. This study uses physiological and transcriptomic analysis to validate previous findings relating primary metabolism and secondary metabolites in wounded carrots. Our data confirmed that increased wounding intensity strengthened the accumulation of phenolics accompanied by enhancing respiration and showed the loss of fructose and glucose and the increase of energy status in carrots. In addition, transcriptomic evaluation of shredded carrots indicated that the respiratory metabolism, sugar metabolism, energy metabolism, and phenolic biosynthesis related pathways, such as “citrate cycle (TCA cycle)”, “oxidative phosphorylation” and “phenylpropanoid biosynthesis”, were activated by wounding. Also, the differentially expressed genes (DEGs) involved in the conversion of sugars to phenolics were extensively up-regulated after wounding. Thus, the physiological and transcriptomic data validate previous findings that wounding accelerates the primary metabolisms of carrot including respiratory metabolism, sugar metabolism, and energy metabolism to meet the demand for the production of phenolic antioxidants.Keywords: carrot; phenolic antioxidants; primary metabolism; RNA-Seq; wounding;

•Increased wounding intensity and temperature enhanced phenolics content of carrot.•Higher temperature increased the antioxidant activity of wounded carrots.•DPI inhibited enzymes associated to phenolic accumulation at 20 °C.•DPI inhibited antioxidant enzymes at 20 °C.Reactive oxygen species (ROS) have been shown to play important roles in biosynthesis of phenolic antioxidants in wounded carrots. This study has gone further to understand the effects of storage temperature on phenolics accumulation in wounded carrots. The results indicated that both increased wounding intensity and higher storage temperature promoted the generation of ROS and enhanced phenolics accumulation in wounded carrots. Moreover, treatment with ROS inhibitor inhibited ROS generation, suppressed the activities of key enzymes in phenylpropanoid pathway (phenylalanine ammonia lyase, PAL; cinnamate-4-hydroxylase, C4H; 4-coumarate coenzyme A ligase, 4CL) and restrained phenolics accumulation in shredded carrots confirming previous reports. In contrast, treatment with ROS elicitor promoted ROS generation, enhanced the activities of PAL, C4H and 4CL, and induced phenolics accumulation. Thus, our results confirmed that ROS are essential for mediating wound-induced phenolics accumulation in carrots and suggested that increase temperature enhanced the accumulation of phenolics through inducing ROS generation.

•UV-C treatment directly induced disease resistance against B. cinerea in strawberry fruit.•UV-C treatment enhanced activities of defense-related enzymes and antioxidant enzymes in strawberry fruit.•Defense-related genes expression was up regulated by UV-C treatment in strawberry fruit.The effect of ultraviolet C (UV-C) treatment on controlling gray mold caused by Botrytis cinerea in strawberry fruit and the possible mechanisms were investigated. The results showed that UV-C treatment significantly reduced lesion diameter and enhanced activities of chitinase (CHI), β-1, 3-glucanase, phenylalanine ammonia-lyase (PAL), peroxidase (POD) and polyphenoloxidase (PPO) in strawberry fruit. Total phenolic content were also increased by UV-C treatment. The activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were also higher in UV-C treated strawberry fruit than those in control. Expression of three defense related genes such as CCR-1 allele, CAT, CHI2, PPO and PLA6 was greatly induced in UV-C treated strawberry fruit. These results suggested that UV-C treatment directly activated disease resistance against gray mold caused by B. cinerea in strawberry fruit.

•Fluorescent and LED green light treatment extended shelf life of broccoli florets stored at 25 °C.•LED green light significantly inhibited the decrease of chlorophyll contents in broccoli florets stored at 25 °C.•LED green light enhanced total phenols and glucosinolates content in broccoli florets stored at 25 °C.The effect of light treatment (fluorescent and light-emitting diode (LED) green light) on shelf life, visual quality and bioactive compounds in broccoli florets was investigated. The results showed that light treatment extended shelf life and inhibited the decrease of H value and chlorophyll contents in broccoli florets stored at 25 °C. The content of total phenols and glucosinolates were markedly increased by LED green light, but no effect on sulforaphane. Fluorescent and LED green light treatment significantly increased DPPH radical scavenging activity in broccoli, but little effect was found between the two light treatments. These results indicated that LED green light could be a useful technique for extending shelf life, maintaining visual quality and preventing decrease of bioactive compounds in broccoli florets.

•BABA-treated cherry fruit exhibited higher firmness than the control fruit.•BABA reduced PG and PME activities, delayed the degrading of cell wall constituents.•BABA inhibited the increase of membrane permeability and malondialdehyde content.•BABA maintained smooth cuticle and integrated structure of subepidermic cell.The effects of postharvest β-aminobutyric acid (BABA) treatment on fruit firmness, pectin degrading enzymes, cell wall constituents and microstructural alterations of pericarp in sweet cherry fruit were investigated. BABA significantly delayed the decline of fruit firmness and inhibited the increase of membrane permeability and the accumulation of malondialdehyde in cherries. The BABA-treated fruit exhibited significantly higher contents of water-soluble pectin, CDTA-soluble pectin, Na2CO3-soluble pectin, total pectin, cellulose and hemicellulose than the control during storage. Activities of pectin degrading enzymes including polygalacturonase and pectinmethylesterase were markedly reduced by BABA treatment. Observations by scanning electron microscopy showed BABA maintained smooth cuticle and integrated structure of subepidermal cell in sweet cherry. These results suggest that the delay in fruit senescence by BABA may be due to depressed membrane permeability and malondialdehyde content, reduced activities of polygalacturonase and pectinmethylesterase, enhanced cell wall polysaccharides content, and integrated subepidermal cell structure in sweet cherry.

The influence of low-temperature conditioning (LTC) treatment on chilling injury, glycine betaine content, and energy metabolism in loquat fruit at 1 °C storage was investigated. The results indicated that LTC treatment significantly reduced chilling injury index, ion leakage, and malondialdehyde content in loquat fruit. Betaine aldehyde hydrogenase (BADH) activity and endogenous glycine betaine (GB) content in loquats treated with LTC were significantly higher than those in control fruit. Moreover, LTC treatment induced activities of energy metabolism-associated enzymes, including H+-adenosine triphosphatase, Ca2+-adenosine triphosphatase, succinic dehydrogenase, and cytochrome c oxidase. LTC treatment triggered obviously higher levels of adenosine triphosphate (ATP) content and energy charge in loquat fruit. These results showed that LTC possibly alleviated chilling injury and enhanced chilling tolerance of loquat fruit by enhancing endogenous GB content and energy status.

•‘Qingzhong’ fruit experienced stronger disease resistance than ‘Fuyang’.•‘Qingzhong’ fruit showed higher activities of antioxidant enzymes.•The resistant cultivar manifested higher contents of linolenic and linoleic acids.•Loquat disease resistance was due to antioxidant system and unsaturated fatty acids.Two cultivars of loquat fruit were stored at 20 °C for 10 days to investigate the relationship between disease resistance, and fatty acid composition and activities of endogenous antioxidant enzymes. The results showed that decay incidence increased with storage time in both cultivars. A significantly lower disease incidence was observed in ‘Qingzhong’ fruit than in ‘Fuyang’, suggesting ‘Qingzhong’ had increased disease resistance. Meanwhile, ‘Qingzhong’ fruit also had lower levels of superoxide radical and hydrogen peroxide, and lower lipoxygenase activity, but higher levels of linolenic and linoleic acids and higher activities of catalase (CAT) and ascorbate peroxidase (APX) compared with ‘Fuyang’. These results suggest that the higher levels of linolenic and linoleic acids and the higher activity of CAT and APX have a role in disease resistance of postharvest loquat fruit.

•The levels of energy status were increased by oxalic acid during the cold storage in peach fruit.•Oxalic acid enhanced enzymes activities of H+-ATPase, Ca2+-ATPase, succinic dehydrogenase and cytochrome C oxidase in peaches.•Oxalic acid maintained high ratio of unsaturated/saturated fatty acid in peach fruit.The effects of postharvest oxalic acid (OA) treatment on chilling injury, energy metabolism and membrane fatty acid content in ‘Baifeng’ peach fruit stored at 0 °C were investigated. Internal browning was significantly reduced by OA treatment in peaches. OA treatment markedly inhibited the increase of ion leakage and the accumulation of malondialdehyde. Meanwhile, OA significantly increased the contents of adenosine triphosphate and energy charge in peach fruit. Enzyme activities of energy metabolism including H+-adenosine triphosphatase, Ca2+-adenosine triphosphatase, succinic dehydrogenase and cytochrome C oxidase were markedly enhanced by OA treatment. The ratio of unsaturated/saturated fatty acid in OA-treated fruit was significantly higher than that in control fruit. These results suggest that the alleviation in chilling injury by OA may be due to enhanced enzyme activities related to energy metabolism and higher levels of energy status and unsaturated/saturated fatty acid ratio.

•MeJA treatment induced disease resistance in postharvest loquat fruit.•MeJA treated fruit manifested higher contents of polyamines.•MeJA maintained higher levels of ATP.•MeJA induced disease resistance due to the increased polyamines and ATP.The effect of methyl jasmonate (MeJA) on changes in polyamines content and energy status and their relation to disease resistance was investigated. Freshly harvested loquat fruit were treated with 10 μmol l−1 MeJA and wound inoculated with Colletotrichum acutatum spore suspension (1.0 × 105 spores ml−1) after 24 h, and then stored at 20 °C for 6 days. MeJA treatment significantly reduced decay incidence. MeJA treated fruit manifested higher contents of polyamines (putrescine, spermidine and spermine) compared with the control fruit, during storage. MeJA treatment also maintained higher levels of adenosine triphosphate, and suppressed an increase in adenosine monophosphate content in loquat fruit. These results suggest that MeJA treatment may inhibit anthracnose rot by increasing polyamine content and maintaining the energy status.

The effects of a combined treatment of hot air (HA, 38 °C for 6 h) and methyl jasmonate (MeJA, 16 μmol L−1) on chilling injury, fruit quality, and physiological changes in loquat fruit stored at 1 °C were investigated. The results showed that treatment with HA or MeJA alone both significantly alleviated chilling injury in loquat fruit compared with the control, while their combination had the lowest level of chilling injury symptoms and highest quality. The activities of antioxidant enzymes such as superoxide dismutase, ascorbate peroxidase, and catalase were enhanced by the combination of HA and MeJA. In addition, the combined treatment significantly inhibited the activities of phenylalanine ammonia-lyase, peroxidase, and polyphenol oxidase, which resulted in lower lignin content. Highest level of polygalacturonase activity and water-soluble pectin content and lowest level of protopectin content were also observed in the combined treatment. These results suggested that the enhanced chilling tolerance by combination of HA and MeJA treatment in loquat fruit was related to the induction of antioxidant enzymes and the inhibition of lignin biosynthesis. The combination of HA and MeJA treatment could be a useful technique to alleviate chilling injury and maintain quality of loquat fruit during cold storage.

The biocontrol effects of Bacillus cereus AR156 on Rhizopus rot caused by Rhizopus stolonifer in postharvest peach fruit and the possible mechanisms were investigated. The results showed that fruit treated with B. cereus AR156 had significantly lower disease incidence and smaller lesion diameter than the control fruit did. B. cereus AR156 treatment remarkably enhanced activities of chitinase and β-1,3-glucanase, promoted accumulation of H2O2, and improved total phenolic content and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity. Transcripts of four defense related genes were only significantly enhanced in fruit both treated with B. cereus AR156 and inoculated with R. stolonifer compared with those that were only treated with B. cereus AR156 or inoculated with R. stolonifer. These results suggest that B. cereus AR156 can effectively inhibit Rhizopus rot caused by R. stolonifer and enhance antioxidant activity in peach fruit through the priming of defense responses.Highlights► Bascillus cereus AR156 effectively inhibited Rhizopus rot caused by Rhizopus stolonifer in peaches. ► DPPH radical-scavenging activity was significantly improved by B. cereus AR156. ► B. cereus AR156 induced disease resistance through priming of defense responses.

Loquat fruit were pretreated with 10 μmol l−1 methyl jasmonate (MeJA) for 24 h at 20 °C and then stored at 1 °C for 35 days to investigate the effect of MeJA treatment on chilling injury (CI) and changes in the contents of proline and γ-aminobutyric acid (GABA). The control fruit exhibited severe flesh leatheriness, a specific CI symptom, after 21 days of storage at 1 °C, but it was reduced in MeJA-treated fruit. During the development of CI in fruit, proline and GABA accumulated with the storage time, while MeJA treatment enhanced the increases in proline and GABA contents. The MeJA-treated fruit exhibited higher activities of Δ1-pyrroline-5-carboxylate synthetase (P5CS), ornithine δ-aminotransferase (OAT) and glutamate decarboxylase (GAD), and lower proline dehydrogenase (PDH) activity than control during storage. These results suggest that the reduction in CI in loquat fruit by MeJA may be due to the increased proline and GABA contents.Highlights► The levels of proline and GABA increased during the chilling development in loquat fruit. ► MeJA regulated enzymes involved in proline and GABA metabolism in loquat fruit. ► MeJA alleviated chilling in loquat fruit due to the increased proline and GABA partly.

The effects of cultural system and essential oil treatment on antioxidant capacities in raspberries were evaluated. Raspberries were hand-harvested from organic and conventional farms in Maryland, USA, and were treated with essential oil including carvacrol, anethole, cinnamic acid, perillaldehyde, cinnamaldehyde, and linalool. Results from this study showed that raspberries grown from organic culture exhibited higher value of antioxidant capacities and individual flavonoids contents. Moreover, the organic culture also enhanced the activities of antioxidant enzymes. In addition, essential oil treatments promoted the antioxidant enzymes activities and antioxidant capacities of raspberries, and the most effective compound was perillaldehyde. In conclusion, raspberries produced from organic culture contained significantly higher antioxidant capacities than those produce from conventional culture. Postharvest essential oil treatments have positive effect on enhancing antioxidant capacities in raspberries from both organic and conventional cultures.Highlights► Organic raspberries had higher antioxidant capacities than conventional raspberries. ► Antioxidant capacities in raspberries were enhanced by postharvest essential oil treatments. ► Perillaldehyde was the most effective compound tested for enhancing the antioxidant capacities.

The effect of 6-benzylaminopurine (6-BA) on the color, antioxidant activity, and contents of total phenols, glucosinolate, and sulforaphane in broccoli florets was investigated. The results showed that 6-BA treatment markedly inhibited the increase of the L* value and malondialdehyde (MDA) content and retarded the decrease of the H value. 6-BA treatment reduced the rate of chlorophyll degradation by regulating the activities of chlorophyllase and Mg-dechelatase. When compared to control florets, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT) were enhanced in florets treated with 6-BA, whereas the activity of peroxidase (POD) was significantly reduced. The contents of total phenols, glucosinolate, and sulforaphane in broccoli florets were also profoundly increased after treatment with 6-BA. These results indicated that 6-BA could maintain the quality, delay senescence, and improve the nutritional value of broccoli.

The effects of salicylic acid (SA; 1 mmol L–1) and ultrasound treatment (40 kHz, 10 min) either separately or combined on the chilling injury (CI) in cold-stored peach fruit (Prunus persica Batsch cv. Baifeng) were investigated. The results showed that SA treatment alone alleviated CI during storage. Ultrasound alone had no influence, but when it was combined with SA, it resulted in greater inhibition of CI than SA alone. The activities of antioxidant enzymes, such as catalase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase, were induced by a combination of SA with ultrasound. In addition, the combined treatment also increased the endogenous SA concentrations in peaches. These results suggested that the induced tolerance against CI by the combination of ultrasound and SA treatment in cold-stored peach fruit was related to the induction of antioxidant enzymes and the increase in the SA concentration.

The effects of essential oil treatment on fruit decay and antioxidant capacities in Chinese bayberries were evaluated. Chinese bayberries were treated with essential oils, including carvacrol, cinnamaldehyde, perillaldehyde, and linalool. Results from this study indicated that all essential oils significantly reduced fruit decay of Chinese bayberries, and the most effective compound was carvacrol. Treatment with carvacrol, cinnamaldehyde, perillaldehyde, and linalool significantly increased total phenolic, anthocyanin, and individual flavonoid contents. In addition, all essential oils maintained significantly higher antioxidant capacities as measured by scavenging capacity against superoxide, hydroxyl, and 1,1-diphenyl-2-picrylhydrazyl radicals and by the reducing power test compared to the control. Moreover, the activities of antioxidant enzymes were also enhanced by all essential oils. Thus, postharvest essential oil treatment has positive effects on reducing decay and enhancing antioxidant capacities in Chinese bayberries.

Broccoli deteriorates very quickly after harvest at ambient temperature due to the loss of green color and the consequent yellowing of florets. To search for an effective method to control quality deterioration, the effect of ethanol treatment on visual quality, antioxidant enzymes and health-promoting compounds in broccoli florets was investigated. Ethanol treatment (500 μL/L) markedly extended shelf-life, inhibited the increase of L* value and the decrease of H value. It also reduced the rate of chlorophyll degradation by inhibiting the activities of chlorophyllase, Mg-dechelatase and peroxidase. In addition, the 1, 1-diphenyl-2-picrylhydrazyl radical scavenging activity and the activities of superoxide dismutase, ascorbate peroxidase and catalase were enhanced in florets treated with ethanol. The contents of total phenolic compounds, glucosinolates and sulforaphane in broccoli were also profoundly increased after treating with ethanol. These results indicated that a postharvest application of ethanol can prolong shelf-life, maintain visual quality and enhance the nutritional value of broccoli florets.

Two cultivars of loquat fruit with contrasting chilling resistance were stored at 1 °C for 35 days to investigate the relationship between chilling injury and fatty acid composition and its antioxidant system. No symptoms of chilling injury occurred in the fruit of ‘Qingzhong’ cultivar during the whole storage, whereas in ‘Fuyang’ fruit, chilling injury increased sharply after 21 days of storage at 1 °C. ‘Qingzhong’ fruit had lower levels of superoxide radical and H2O2, in addition to lower lipoxygenase activity, but higher membrane lipid unsaturation and higher activities of superoxide dismutase and catalase than ‘Fuyang’. Furthermore, the chilling resistant ‘Qingzhong’ fruit also showed higher activities of antioxidant enzymes involved in ascorbate–glutathione cycle and higher levels of ascorbate acid and reduced glutathione. These results suggest that the higher membrane lipid unsaturation and the more efficient antioxidant system were both beneficial in enhancing resistance of loquat fruit to chilling injury.Research highlights► Chilling resistance of loquat fruit differed from the cultivars. ► ‘Qingzhong’ fruit manifested higher membrane lipid unsaturation. ► The resistant cultivar showed higher activities of antioxidant enzymes. ► Loquat chilling resistance was due to lipid unsaturation and antioxidant system.

Peach fruit were immersed in 5 mM γ-aminobutyric acid (GABA) solution for 10 min at 20 °C and then stored at 1 °C for 5 weeks to investigate the effect of GABA treatment on chilling injury (CI), antioxidant enzymes and energy status in peach fruit. The results showed that GABA treatment significantly inhibited CI incidence of peaches and enhanced activities of antioxidant enzymes, such as superoxide dismutase, catalase, ascorbate peroxidase, glutathione peroxidase, glutathione S-transferase, monodehydroascorbate reductase and dehydroascorbate reductase. The treatment also increased contents of adenosine triphosphate and adenosine diphosphate, but lowered adenosine monophosphate content, which resulted in a higher level of energy charge in treated fruit. These results indicated that GABA increased chilling tolerance of peach fruit through enhancing its enzymatic antioxidant system and maintaining energy status in peach fruit.Highlights► GABA treatment inhibited chilling injury development in cold-stored peach fruit. ► GABA treatment induced higher activities of antioxidant enzymes. ► GABA-treated fruit showed higher ATP content and energy charge. ► Chilling tolerance was induced by GABA in peaches, due to increased ATP content and antioxidant system.

The effects of Chinese bayberry fruit extract (CBFE) ingestion on hepatic and colonic oxidative stress and 1,2-dimethylhydrazine (DMH)-induced intestinal aberrant crypt foci (ACF) development in rats were investigated. Rats were administered DMH (35 mg/kg body weight) and were supplemented with CBFE (50 or 500 mg/kg body weight every day) for 16 weeks. Results showed that DMH consumption induced intestinal ACF development and adenoma or adenocarcinoma formation, which were significantly reduced with CBFE supplement. The CBFE treatments increased reduced glutathione levels and activities of superoxide dismutase, catalase and glutathione reductase, in both hepatic and colonic tissues; however, the activities of glutathione-S-transferase and glutathione peroxidase were inhibited. These results indicate that CBFE, rich in phenolic compounds, effectively inhibits DMH-induced ACF and colonic tumour development by alleviating oxidative stress.

The effect of exogenous γ-aminobutyric acid (GABA) on chilling injury of peach fruit was investigated. Freshly harvested peaches were treated with 1, 5, or 10 mM GABA at 20 °C for 10 min and then stored at 1 °C for up to 5 weeks. The results showed that all of the GABA treatments could reduce chilling injury of peach fruit with 5 mM being the most effective concentration. GABA treatment significantly enhanced the accumulation of endogenous GABA and proline, which resulted from the increased activities of glutamate decarboxylase, Δ1-pyrroline-5-carboxylate synthetase, and ornithine δ-aminotransferase and decreased proline dehydrogenase activity. Our results revealed that GABA treatment may be a useful technique to alleviate chilling injury in cold-stored peach fruit, and the reduction in chilling by GABA may be due to the induction of endogenous GABA and proline accumulation. These data are the first evidence that exogenous GABA induced chilling tolerance in postharvest horticultural products.

Loquat fruit were pretreated with 10 μM methyl jasmonate (MeJA) for 24 h at 20 °C, and then stored at 1 °C for 35 days to investigate the effect of MeJA treatment on cell wall modification in relation to chilling injury. Loquat fruit developed chilling injury, manifested as increased fruit firmness and internal browning, decreased extractable juice during storage. These chilling injury symptoms were significantly reduced by MeJA treatment. MeJA also markedly delayed the increases in lignin, alcohol insoluble residues, hemicellulose and cellulose. Meanwhile, the MeJA-treated fruit exhibited significantly lower activities of phenylalanine ammonia lyase, peroxidase, polyphenol oxidase and higher polygalacturonase activity than the control during storage. The levels of water- and CDTA-soluble pectins in MeJA-treated fruit were also significantly higher than that in the control. These results suggest that the reduction in chilling injury by MeJA may be due to inhibited lignin accumulation and enhanced cell wall polysaccharides solubilisation.

The effects of methyl jasmonate (MeJA) in combination with ethanol (EtOH) treatment on green mold rot caused by Penicillium citrinum, natural decay, and antioxidant capacity in harvested Chinese bayberries were investigated. MeJA at 10 μmol L−1 in combination with EtOH at 22.32 μmol L−1 was most effective in reducing green mold rot and natural decay. This combined treatment also significantly inhibited spore germination and germ tube elongation of the pathogen in vitro compared with MeJA alone or control. Meanwhile, the combination-treated bayberries exhibited highest reducing power, scavenging activities against superoxide, hydroxyl, and 1,1-diphenyl-2-picrylhydrazyl radicals, and contents of total phenolics, flavonoids, and anthocyanins as well as individual phenolic compounds. Fruit quality parameters were not significantly affected by these treatments. These results suggest that the combination of MeJA and EtOH had an additive effect in reducing postharvest decay and improving antioxidant capacity in Chinese bayberries.

Loquat fruit were pre-treated with 10 μmol/l methyl jasmonate (MeJA) for 24 h at 20 °C, and then stored at 1 °C for 35 days to investigate the effect of MeJA treatment on chilling injury and changes in the antioxidant system. Loquat fruit developed chilling injury, manifested as increased fruit firmness, decreased extractable juice rate and internal browning during storage. These chilling injury symptoms were significantly reduced by MeJA treatment. MeJA also markedly delayed the increases in O2− production rate and H2O2 content. Meanwhile, the MeJA-treated fruit exhibited significantly higher activities of superoxide dismutase, catalase and ascorbate peroxidase, and lower activity in lipoxygenase than control fruit during the storage. The ratio of unsaturated/saturated fatty acid in MeJA-treated fruit was also significantly higher than that in control fruit. These results suggest that the reduction in chilling injury by MeJA may be due to enhanced antioxidant enzyme activity and higher unsaturated/saturated fatty acid ratio.

The effects of methyl jasmonate (MeJA) on postharvest decay and antioxidant capacity in harvested Chinese bayberry fruit were investigated. Chinese bayberries were treated with 0, 1, 10, 100, or 1000 μmol L−1 MeJA at 20 °C for 6 h and then stored at 0 °C for 12 days. MeJA at 10 μmol L−1 was most effective in reducing fruit decay; quality parameters including pH value, total soluble solids, and titratable acidity were not significantly affected by MeJA treatment. Fruit treated with 10 μmol L−1 MeJA exhibited significantly higher phenylalanine ammonia-lyase activity and higher levels of total phenolics, flavonoids, and anthocyanins as well as individual phenolic compounds than control. These fruits also maintained significantly higher antioxidant activity as measured by scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl, superoxide, and hydroxyl radicals and by the reducing power test compared to the control. These results indicate that MeJA can effectively reduce fruit decay and improve antioxidant capacity of Chinese bayberry fruit.

Loquat fruit was treated with 2.32 nmol L−1 1-methylcyclopropene (1-MCP) for 24 h at 20 °C, and then stored at 1 °C for 35 days to investigate the effect of 1-MCP treatment on chilling injury (CI) and fatty acid and cell wall polysaccharide composition. Loquat fruit developed CI, manifested as increased fruit firmness, internal browning and decreased extractable juice. These CI symptoms were reduced by 1-MCP treatment. 1-MCP-treated fruit exhibited higher levels of linoleic and linolenic acid and a higher unsaturated/saturated fatty acid ratio than control fruit during storage. The treatment also markedly delayed increase in alcohol insoluble residue, i.e. hemicellulose and cellulose. Meanwhile, the level of water- and CDTA-soluble pectins in treated fruit was higher than that in control. Our result suggested modifications of fatty acid and cell wall polysaccharide composition are associated with CI develpoment in loquat and 1-MCP treatment modulates the changes that seem to regulate the strength of cell wall and so to alleviate CI.

The influence of high O2 atmosphere on postharvest decay, quality, total phenolic, total anthocyanin contents, antioxidant enzymes activity, and antioxidant activity of Chinese bayberry fruit was investigated. Freshly harvested Chinese bayberry fruits were placed in jars and ventilated continuously with air or with 80 and 100% O2 for up to 12 days. Samples were randomly selected initially and at 3-days interval during storage. The fruit exposed to high O2 was resistant to decay, had high levels of total soluble solids, titratable acidity and ascorbic acid contents, and also reduced the increment of pH value. High O2 treatment was less stressful as reflected by having the significantly lower malonaldehyde contents and higher catalase, ascorbic acid peroxidase, and peroxidase activities during storage. Both 80% and 100% O2 treaments had also retained the bioactive contents and 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity during storage. These results indicate that elevated O2 levels may improve the ability of the antioxidative defense mechanism in Chinese bayberry and result in a better control of fruit decay.

The effect of hot air (HA, 45°C, 3.5 h) treatment on reducing gray mold caused by Botrytis cinerea in strawberry fruit and the possible mechanisms were investigated. The results showed that HA treatment significantly reduced lesion diameter and enhanced activities of chitinase (CHI), β-1,3-glucanase and phenylalanine ammonia-lyase (PAL) in strawberry fruit. Total phenolic contents were also increased by HA treatment. The activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were higher in HA treated strawberry fruit than those in control. Expression of three defense related genes such as CAT, CCR-1 allele and PLA6 was greatly induced in HA treated strawberry fruit with or without inoculation by B. cinerea. In addition, the in vitro experiment showed that HA treatment inhibited spore germination and tube growth of B. cinerea. These results suggested that HA treatment directly activated disease resistance against B. cinerea in strawberry fruit without priming response and directly inhibiting growth of B. cinerea.

This study investigated the regulation of ascorbate acid (AsA) and glutathione metabolism and chilling tolerance by methyl jamonate (MeJA) in loquat fruit. The results showed that application of MeJA to loquat fruit inhibited the incidence of chilling injury manifested as internal browning (IB) and increased AsA and reduced glutathione (GSH) contents due to the inhibition of ascorbate oxidase activity and enhancement of monodehydroascorbate reductase, dehydroascorbate reductase and glutathione reductase activities. Meanwhile, MeJA also enhanced activities of ascorbate peroxidase, glutathione peroxidase and glutathione-S-transferase. Our results suggested that MeJA can regulate the ascorbate and glutathione metabolism and has important roles in alleviating oxidative damage and enhancing chilling tolerance in loquat fruit.Research highlights▶ The levels of AsA and GSH decreased during the chilling development in cold-stored loquat fruit. ▶ MeJA regulated enzymes involved in the ascorbate and glutathione metabolism in loquat fruit. ▶ MeJA treatment alleviated chilling symptoms in loquat fruit due to the increased AsA and GSH.

•Higher temperature enhanced phenolic accumulation and antioxidant activity.•Higher temperature enhanced ROS production and antioxidant enzyme activity.•Glucose/glucose oxidase increased ROS production and phenolic accumulation at 15 °C.•Diphenyliodonium iodide inhibited ROS production and phenolic accumulation at 15 °C.The effect of temperature on phenolic accumulation in fresh-cut pitaya fruit was reported during storage at 5, 10 and 15 °C. Fresh-cut pitaya fruit were treated with ROS production inhibitor (diphenyliodonium iodide, DPI) or elicitor (glucose/glucose oxidase, G/GO) and the total soluble phenolics (TSP) content, antioxidant activity (AOX), phenylalanine ammonia lyase (PAL) activity, as well as ROS production and antioxidant enzymes activity were determined. Results showed that higher storage temperature promoted the production of ROS, enhanced the accumulation of TSP and improved the AOX of fresh-cut pitaya fruit. Moreover, treatment with DPI dramatically inhibited ROS generation, PAL activity and TSP accumulation, while G/GO treatment significantly increased ROS level, PAL activity and TSP accumulation. These results demonstrate that phenolics accumulate with increasing temperature and confirm previous report of ROS effects on wound induced phenolic accumulation in pitaya fruit.

•Cutting styles did not have adverse effect on the organoleptic quality.•Cutting significantly enhanced TP content, antioxidant enzyme activity and AOX.•The enhancement of TP content and AOX increased with cutting wound intensity.The effect of different cutting styles on the quality and antioxidant activity of pitaya fruit during 4 d of storage at 15 °C was investigated. Pitaya fruit was cut into slice, half-slice and quarter-slice, all in 1 cm of thickness, with corresponding wounding intensity (A/W) of 2.0, 2.9 and 3.7 cm2 g−1, respectively.Resultsshowed that cutting styles had little influence on fruit quality parameters such as vitamin C, soluble solids, titratable acidity and flesh color. While total phenolic content, antioxidant activity, and phenylalanine ammonia-lyase activity increased significantly with cutting wounding intensity at the first 2 d of storage. In addition, fresh-cut processing induced the reactive oxygen species (ROS) generation and enhanced the activity of antioxidant enzymes including catalase, superoxide dismutase and glutathione reductase at the initial storage time. These results demonstrated that cutting styles didn’t have much adverse effect on the organoleptic quality, but significantly induced the biosynthesis of phenolics and improved the antioxidant activity of fresh-cut pitaya fruit. Moreover, ROS may act as signaling molecules in the accumulation of phenolics in fresh-cut pitaya fruit.

The effect of methyl jasmonate (MeJA) on reducing anthracnose rot caused by Colletotrichum acutatum infection in postharvest loquat fruit (Eriobotrya japonica L. cv. Jiefangzhong) and the possible mechanisms involved were investigated. Freshly harvested loquat fruit were treated with 10 μmol/L MeJA at 20 °C for 24 h. Both the treated and the untreated fruit were artificially wounded and inoculated with Colletotrichum acutatum spore suspension (1.0 × 105 spores/mL) 1 day after the treatment, and then incubated at 20 °C for 6 days. Treatment of loquat fruit with MeJA resulted in significantly lower disease incidence and smaller lesion diameters than in control fruit. MeJA treatment significantly inhibited activities of catalase (CAT) and ascorbate peroxidase (APX) while superoxide dismutase (SOD) activity was not significantly affected in early infection, thus resulting in a higher level of H2O2 in the earlier period of incubation. The enhanced H2O2 generation by MeJA treatment might serve as a signal to induce resistance against C. acutatum infection. However, MeJA treatment inhibited the increase in phenylalanine ammonia-lyase (PAL), polyphenoloxidase (PPO) and peroxidase (POD) activities and lignin content, indicating that lignification is not the major defense mechanism against anthracnose rot in loquat fruit. The in vitro experiment showed that MeJA significantly inhibited spore germination, germ tube elongation and mycelial growth of C. acutatum. These results suggest that MeJA treatment can effectively inhibit anthracnose rot caused by C. acutatum in postharvest loquat fruit. It is postulated that the control of the disease is directly because of the inhibitory effect of MeJA on pathogen growth, and indirectly because of the induced disease resistance triggered by enhanced H2O2 levels.

Peaches (Prunus persica Batsch cv Baifeng) were harvested at the firm-mature stage and treated with various combinations of methyl jasmonate (MJ) and hot air (HA). Severity of internal browning and flesh mealiness, firmness, extractable juice, total soluble solids (TSS), total acid, vitamin C and total phenolic contents were measured after 3 and 5 weeks of storage at 0 °C plus 3 d at 20 °C for shelf-life. The activities of phenylalanine ammonia-lyase (PAL, EC 4.3.1.5), superoxide dismutase (SOD, EC 1.15.1.1), polyphenol oxidase (PPO, EC 1.10.3.1), peroxidase (POD, EC 1.11.1.7), pectin-methylesterase (PME, EC 3.1.1.11) and polygalacturonase (PG, EC 3.2.1.15) were analyzed during the cold storage period. The results showed that fruit treated with 1 μmol L−1 MJ vapor at 38 °C for 12 h (HMJ), and heat treatment at 38 °C for 12 h and then treated with 1 μmol L−1 MJ vapor at 20 °C for 24 h (HA + MJ) had the highest quality and lowest percent of chilling injury symptoms. HA treatment alone significantly inhibited internal browning, but caused more severe flesh mealiness than other treatments. This side effect was counteracted by MJ. The percent of extractable juice in combined treatments was higher than that in the control, however, no significant effect was found on firmness. TSS was 23% and 25.3% higher and total acid was 59.4% and 62.5% higher in treatments of HMJ and HA + MJ, respectively, than those in control fruit after storage for 5 weeks. Vitamin C and total phenolic contents were also maintained at higher levels in combined treatments. In addition, the combined treatments resulted in higher activities of PAL, SOD and PG, and lower activities of PPO, and POD than the control. The combination of HA and MJ vapor treatment might be a useful technique to alleviate chilling injury and maintain peach fruit quality during cold storage.

•Treatment with 10 μmol L−1 of MeJA significantly suppressed gray mold caused by B. cinerea in harvested table grapes.•MeJA treatment significantly enhanced enzyme activity and expression of defense related genes.•MeJA induced disease resistance against B. cinerea by priming of defense responses.The effect of a postharvest treatment with 10 μmol/L of methyl jasmonate (MeJA) on controlling gray mold decay caused by Botrytis cinerea in table grapes and the possible action mechanisms were investigated. The results indicated that MeJA treatment significantly reduced the incidence and development of gray mold decay in grapes. Meanwhile, MeJA treatment markedly enhanced activities of superoxide dismutase (SOD) and catalase (CAT), decreased ascorbate peroxidase activity, promoted the accumulation of H2O2 and improved the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. MeJA treatment also significantly enhanced activities of defense related enzymes including chitinase (CHI), β-1,3-glucanase (GNS), phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD). Moreover, transcripts of defense related genes encoding CHI, GNS, PAL, SOD and CAT were only significantly enhanced in fruit pre-treated with MeJA and then inoculated with B. cinerea compared with those that were only treated with MeJA or inoculated with B. cinerea. These results suggested that 10 μmol/L of MeJA treatment primes defense responses for enhanced disease resistance against Botrytis cinerea and thus reducing gray mold decay in harvested table grapes.

•Postharvest quality of Welsh onions declined with increased wounding intensity.•Higher storage temperature enhanced quality loss of fresh-cut Welsh onions.•The shelf life of slices and pieces was longer than shreds.•Increased wounding intensity promoted the antioxidant activity of Welsh onions.•Higher storage temperature enhanced the antioxidant activity of Welsh onions.Welsh onion (Allium fistulosum L.) is a very popular, medicinal and functional vegetable in East Asian countries. Welsh onion can be processed into different cuts and widely used as flavoring agent in food processing. In this study, the effects of wounding intensity (slices, pieces, and shreds) and storage temperature (4 and 20 °C) on postharvest quality and antioxidant activity of fresh-cut Welsh onions were studied. Our results showed that increased wounding intensity and higher storage temperature both led to the sharp rise of respiration rate, and the increasing loss of pungency, soluble solids content and ascorbic acid. On the other hand, the increase of phenylalanine ammonia lyase activity, the accumulation of phenolic compounds and the enhancement of antioxidant capacity were intensified with increased wounding intensity and higher storage temperature. The shelf life of 4 °C stored slices, pieces and shreds was determined to 5 d, while for 20 °C stored samples, this threshold was shortened to 1.5, 1.5 and 1 d, respectively. Thus, our results suggested that increased wounding intensity and higher storage temperature reduce postharvest quality and shorten shelf-life, but increase antioxidant activity of fresh-cut Welsh onions.

•Bacillus subtilis SM21 effectively inhibited Rhizopus rot caused by R. stolonifer in peaches.•B. subtilis SM21 treatment markedly up-regulated the expression of seven defense related genes.•B. subtilis SM21 showed strong antifungal activities against growth of R. stolonifer.The efficacy of Bacillus subtilis SM21 on controlling Rhizopus rot caused by Rhizopus stolonifer in postharvest peach fruit and the possible mechanisms were investigated. The results indicated B. subtilis SM21 treatment reduced lesion diameter and disease incidence by 37.2% and 26.7% on the 2nd day of inoculation compared with the control. The in vitro test showed significant inhibitory effect of B. subtilis SM21 on mycelial growth of R. stolonifer with an inhibition rate of 48.9%. B. subtilis SM21 treatment significantly enhanced activities of chitinase and β-1,3-glucanase, and promoted accumulation of H2O2. Total phenolic content and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity were also increased by this treatment. Transcription of seven defense related genes was much stronger in fruit treated with B. subtilis SM21 or those both treated with B. subtilis SM21 and inoculated with R. stolonifer compared with fruit inoculated with R. stolonifer alone. These results suggest that B. subtilis SM21 can effectively inhibit Rhizopus rot caused by R. stolonifer in postharvest peach fruit, possibly by directly inhibiting growth of the pathogen, and indirectly inducing disease resistance in the fruit.