Expression Analysis of Hexokinase Genes in Kiwifruit during Postharvest Softening

To solve the problem of the rapid softening of postharvest kiwifruit, the effect of 10 mmol/L N-acetyl-D-glucosamine (NAG) treatment on physiological changes, hexokinase (HXK) activity and AcHXKs gene expression in ‘Hongyang’ kiwifruit during postharvest ripening. The results showed that compared with the control group, exogenous NAG treatment could effectively inhibit the respiration rate and ethylene production of kiwifruit, delay the decline of firmness and total acid content, as well as the hydrolysis of starch and pectin, thereby maintaining a lower soluble solid content. In addition, NAG inhibited HXK activity and AcHXK3 expression level, thus affecting sugar and respiratory metabolism. Moreover, the expression of AcHXK7, 8 and 9 was upregulated, which was positively correlated with firmness and probably involved in glucose sensor-mediated postharvest softening of kiwifruit. In conclusion, NAG treatment can induce the differential expression of AcHXK3, 7, 8 and 9, thereby delaying kiwifruit postharvest ripening via catalytic and regulatory functions. These results may provide a theoretical basis for the mechanism of kiwifruit postharvest softening, and also help researchers develop novel strategies for kiwifruit preservation

Effect of ethanol fumigation on pericarp browning associated with phenol metabolism, storage quality, and antioxidant systems of wampee fruit during cold storage

Abstract Wampee fruit is a popular fruit cultivar in South‐East Asia due to its high levels of nutrients and antioxidants; however, pericarp browning leads to a short storage life with great economic loss during years. The purpose of this work was to determine whether postharvest ethanol fumigation affected pericarp browning development of wampee fruit during 12 days of storage at 8 ± 0.5°C, and if so, how it is related to phenol metabolism and how it affects quality attributes and antioxidant systems during storage. After fruits were fumigated with 100, 300, 500, and 800 μl/L for 5 hr at 22 ± 0.5°C, ethanol significantly reduced the development of pericarp browning by increasing total phenolics (TP) content and decreasing the activity of polyphenol oxidase (PPO), especially in 500 μl/L ethanol treatment. Additionally, ethanol delayed the losses in fruit firmness (FF), soluble solid content (SSC), and titratable acidity (TA), retarded weight loss and accumulation of malondialdehyde (MDA) content and maintained relatively high contents of ascorbic acid (AsA), total flavonoids (TF), and total antioxidant capacity (TAC) and activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). In conclusion, results demonstrated that postharvest ethanol fumigation in wampee fruit has ability to reduce pericarp browning development by regulating phenol metabolism and enhancing antioxidant systems

Effects of 1-Methylcyclopropene Treatment on Physicochemical Attributes of “Hai Jiang” Yardlong Bean during Cold Storage

The yardlong bean belongs to nonclimacteric fruit. The objective of this study was to investigate the effects of 1-methylcyclopropene (1-MCP) treatment on physicochemical characteristics of yardlong beans during cold storage. Freshly harvested yardlong beans were treated with different concentrations of 1-MCP (0, 0.75, 1.0, 1.25, and 1.5 μL ·L−1) and stored at 8°C for 21 days. The results showed that, compared with the control, the decrease in firmness and good fruit rate and the degradation of chlorophyll and vitamin C (Vc) content could be inhibited, change in skin color could be delayed, activities of superoxide dismutase (SOD) and peroxidase (POD) could be improved, and the increasing of malondialdehyde (MDA) content and weight loss could be inhibited significantly by 1-MCP treatments. Of the different concentrations of 1-MCP, 1.0 μL·L−1 proved to have the best preservative effects, extending storage time and delaying ripening and senescence of yardlong beans. These results indicated that 1-MCP treatment provided an effective method for delaying the postharvest senescence of fresh yardlong beans

DataSheet_1_Comparative transcriptomic and metabolomic analyses reveal the delaying effect of naringin on postharvest decay in citrus fruit.zip

IntroductionNaringin exhibits antioxidant capacity and can partially inhibit pathogens in many horticultural products, such as citrus fruit; however, the effects of naringin on the storage quality and mechanisms that regulate senescence in citrus fruit have not been comprehensively analyzed.Methods and resultsIn this study, exogenous naringin treatment was found to significantly delay citrus fruit disease, decreasing the H2O2 content, increasing the antioxidant capacity and maintaining the quality of the fruit. Metabolomic analysis of citrus peel indicated the vast majority (325) of metabolites belonging to flavonoids. Moreover, the auraptene, butin, naringenin, and luteolin derivative levels within the phenylpropanoid pathway were significantly higher in the naringin-treated fruit than in the control fruit. Transcriptomic analysis also revealed that twelve genes in the phenylpropanoid and flavonoid biosynthesis pathways were significantly upregulated. Further analysis with a co-expression network revealed significant correlation between these differential genes and metabolites. Additionally, MYC and WRKY, screened from the MAPK signaling pathway, may contribute to naringin-induced disease resistance.ConclusionIn conclusion, naringin treatment can efficiently delay decay and maintain the quality of citrus fruit, mainly by promoting metabolites accumulation, and upregulating differentially expressed genes in phenylpropanoid and flavonoid biosynthesis pathway. This study provides a better understanding of the regulatory mechanisms through which naringin delays citrus fruit decay and maintains fruit quality.</p

Table_1_Exogenous melatonin treatment affects ascorbic acid metabolism in postharvest ‘Jinyan’ kiwifruit.DOCX

Ascorbic acid (AsA) is an important nutritious substance in fruits, and it also can maintain the biological activity of fruits during storage. This research investigated the effect of exogenous melatonin (MT) on AsA metabolism in postharvest kiwifruit. Our results indicated that exogenous MT delayed the decrease of fruit firmness and titratable acid (TA), inhibited the increase of soluble solids content (SSC), reduced the respiration rate and ethylene production, and maintained a higher AsA content in kiwifruit during storage. The high expression of L-galactose pathway key genes in the early storage and regeneration genes in the later storage maintained the AsA content in postharvest kiwifruit. MT treatment enhanced the expression levels of AsA biosynthesis (AcGME2, AcGalDH, and AcGalLDH) and regeneration (AcGR, AcDHAR, and AcMDHAR1) genes. Meanwhile, the expression of the degradation gene AcAO was inhibited in MT-treated kiwifruits.</p

Hot Water Treatment Improves Date Drying and Maintains Phytochemicals and Fruit Quality Characteristics of Date Palm (<i>Phoenix dactylifera</i>)

Fresh date fruits (cvs. Hillawi and Khadrawi) were harvested at the khalal stage and treated with hot water treatment (HWT) for different time durations (control, HWT-1 min, HWT-3 min, HWT-5 min, and HWT-7 min) to investigate the physicochemical characteristics, phytochemical properties, and sensory attributes. The results revealed that both date cultivars took less time to reach the tamar stage in response to HWT-7 min compared to control. However, Hillawi date fruit showed a higher fruit ripening index (75%) at HWT-3 min, while Khadrawi fruit had a higher ripening index (80%) at HWT-5 min than untreated fruit (10%). Higher weight loss and lower moisture contents were observed in Hillawi (25%) and Khadrawi (20%) date fruit as the immersion period increased in both cultivars. Moreover, soluble solid content was higher in Hillawi (11.77° Brix) in response to HWT-3 min and Khadrawi (10.02° Brix) date fruit immersed in HWT-5 min in contrast with the control group, whereas significantly lower levels of titratable acidity and ascorbic acid content were observed in Hillawi (0.162%, 0.67 mg/100 g) and Khadrawi (0.206%, 0.73 mg/100 g) date fruit in response to HWT (HWT-1 min, HWT-3 min, HWT-5 min, and HWT-7 min) than untreated fruit. Furthermore, noticeably higher levels of reducing sugar (69.83%, 57.01%), total sugar (34.47%, 31.14%), glucose (36.84%, 29.42%), fructose (33.99%, 27.61%), and sucrose (3.16%, 1.33%) were found in hot water-treated Hillawi (immersed for 3-min) and Khadrawi (immersed for 5-min) date fruit, respectively. In addition, total phenolic content, total flavonoids, total antioxidants, and total tannins were substantially superior in date fruits subjected to HWT-3 min (in Hillawi, 128 mg GAE/100 g, 61.78%, 20.18 mg CEQ/100 g) and HWT-5 min (in Khadrawi, 139.43 mg GAE/100 g, 72.84%, and 18.48 mg CEQ/100 g) compared to control. Overall, sensory attributes were recorded to be higher in Hillawi and Khadrawi date fruit after treatment for 3 min and 5 min, respectively. Our findings suggest that HWT is a promising technique that can be adopted commercially to improve fruit ripening and preserved nutritional quality of dates after harvest