Plum blossom low molecular weight polypeptide protects HaCaT cells against UVB-induced oxidative damage in vitro and underlying mechanism.

BACKGROUND: Increasing amounts of ultraviolet radiation occur as ozone depletion causes the earth's ozone layer to be destroyed, making antioxidant efficacy a research hotspot. Previous studies on plum blossom have mostly focused on Volatile Oils, Flavonoids, Phenylpropanoids, and other compounds, whereas few studies have focused on low molecular weight polypeptide (LMWP) of plum blossom. This research provides a reference for the deep processing and utilization of plum blossom. OBJECTIVES: (a) Plum blossom low molecular weight polypeptides protect HaCaT cells against UVB-induced oxidative damage in vitro and the underlying mechanism. (b) Improve the theoretical basis for the intense processing and utilization of plum blossom. METHODS: The safe concentration of LMWP and the survival rate of HaCaT cells were determined using the CCK-8 experiment. The fluorescence intensity of reactive oxygen species (ROS) was identified using the dichlorofluorescin diacetate (DCFH-DA) method; Superoxide dismutase (SOD) and malondialdehyde (MDA) concentrations were measured in ruptured cells; Western blot analysis was used to examine the expression levels of three proteins: nuclear factor E2-related factor 2 (Nrf2), heme oxygenase 1 (HO-1), and benzoquinone oxidoreductase 1 (NQO-1). RESULTS: It was noted that a certain concentration of LMWP could promote cell proliferation. In oxidatively damaged HaCaT cells, SOD levels and survival rates were markedly reduced, but ROS and MDA levels were elevated. However, after treatment with LMWP, the survival rate of the cells and SOD levels were markedly increased, and the levels of ROS and MDA were markedly decreased. As shown by Western blotting, the model group exhibited lower levels of Nrf2, HO-1, and NQO-1 expression than the control group, whereas LMWP-treated cells had significantly higher levels of Nrf2, HO-1, and NQO-1 expression than their model-treated counterparts. CONCLUSIONS: LMMP can effectively protect HaCaT cells against oxidative damage in vitro induced by UVB, and the underlying mechanism is linked to the activation of the transcription factor Nrf2.

Exposed anthocyanic leaves of Prunus cerasifera are special shade leaves with high resistance to blue light but low resistance to red light against photoinhibition of photosynthesis.

BACKGROUND AND AIMS: The photoprotective role of foliar anthocyanins has long been ambiguous: exacerbating, being indifferent to or ameliorating the photoinhibition of photosynthesis. The photoinhibitory light spectrum and failure to separate photo-resistance from repair, as well as the different methods used to quantify the photo-susceptibility of the photosystems, could lead to such a discrepancy. METHODS: We selected two congeneric deciduous shrubs, Prunus cerasifera with anthocyanic leaves and Prunus triloba with green leaves, grown under identical growth conditions in an open field. The photo-susceptibilities of photosystem II (PSII) and photosystem I (PSI) to red light and blue light, in the presence of lincomycin (to block the repair), of exposed leaves were quantified by a non-intrusive P700+ signal from PSI. Leaf absorption, pigments, gas exchange and Chl a fluorescence were also measured. KEY RESULTS: The content of anthocyanins in red leaves (P. cerasifera) was >13 times greater than that in green leaves (P. triloba). With no difference in maximum quantum efficiency of PSII photochemistry (Fv/Fm) and apparent CO2 quantum yield (AQY) in red light, anthocyanic leaves (P. cerasifera) showed some shade-acclimated suites, including lower Chl a/b ratio, lower photosynthesis rate, lower stomatal conductance and lower PSII/PSI ratio (on an arbitrary scale), compared with green leaves (P. triloba). In the absence of repair of PSII, anthocyanic leaves (P. cerasifera) showed a rate coefficient of PSII photoinactivation (ki) that was 1.8 times higher than that of green leaves (P. triloba) under red light, but significantly lower (-18 %) under blue light. PSI of both types of leaves was not photoinactivated under blue or red light. CONCLUSIONS: In the absence of repair, anthocyanic leaves exhibited an exacerbation of PSII photoinactivation under red light and a mitigation under blue light, which can partially reconcile the existing controversy in terms of the photoprotection by anthocyanins. Overall, the results demonstrate that appropriate methodology applied to test the photoprotection hypothesis of anthocyanins is critical.

A network pharmacology strategy combined with in vitro experiments to investigate the potential anti-inflammatory mechanism of Prunus cerasifera Ehrhart.

This study aimed to investigate the anti-inflammatory activity of Prunus cerasifera Ehrhart (EHP). LC-MS/MS, network pharmacology, enzyme-linked immunosorbent assay (ELISA), and Western blot analysis methods were used to investigate the chemical composition and the anti-inflammatory mechanism of EHP. The LC-MS/MS results showed that flavonoids and phenolic acids were the major compounds in EHP. The network pharmacology analysis results indicated that EHP was related to TNF, inflammatory cytokine, and MAPK signaling pathway. ELISA and Western blot results showed that EHP impeded the increase in inflammatory factors, inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), nuclear transcription factors κB (p65), MAPK pathway, pyrolytic relevant proteins nod-like receptor family pyrin domain-containing 3 (NLRP3), and interleukin-1ß (IL-1ß) induced by lipopolysaccharide (LPS) and activated the nuclear factor erythroid 2-related factor 2 (Nrf2)/hemeoxygenase-1 (HO-1) pathway. Therefore, this research highlighted the potential application of P. cerasifera in the development of anti-inflammatory foods that prevented inflammatory diseases. PRACTICAL APPLICATIONS: In recent years, many synthetic drugs with anti-inflammatory effect have the disadvantages of high price and side effects. Thus, the development of anti-inflammatory drugs from natural resources has its application value. In this study, LPS-stimulated RAW264.7 cells were used to establish inflammatory model to verify the anti-inflammatory effect of Prunus cerasifera (EHP). The results showed that P. cerasifera possessed anti-inflammatory activity through inhibiting pro-inflammatory cytokines secretion, NF-κB, MAPK pathway, and NLRP3 inflammasome activation. Therefore, P. cerasifera has the potential to develop into functional food to prevent the progress of various inflammatory-related diseases.

Ultra-HPLC-MS pseudo-targeted metabolomic profiling reveals metabolites and associated metabolic pathway alterations in Asian plum (Prunus salicina) fruits in response to gummosis disease.

Plum (Prunus spp.) is an economically and nutritionally important stone fruit that is grown worldwide. Gummosis disease (GD) is one of the most common limiting factors that adversely affects the yield and quality of stone fruits such as plum. Elucidating plum fruit metabolomics responses is essential to develop sustainable agricultural practices to combat GD in the future. Herein, an ultra-high-performance liquid chromatography coupled to mass-spectrometry (UHPLC-MS) pseudo-targeted metabolomic profiling was first performed to elucidate the overall metabolic alterations in Asian plum (Prunus salicina Lindl.) fruit in response to GD. The most pivotal differential metabolites, including certain amino acids and proanthocyanidins, in GD and control groups were identified by combining multivariate data analysis with strict statistical criteria. Metabolic pathway enrichment analysis showed that GD induced a series of coordinated defence responses and reprogramming of various metabolic pathways, including glucosinolate biosynthesis, 2-oxocarboxylic acid metabolism, valine, leucine and isoleucine degradation, and isoquinoline alkaloid biosynthesis pathways. Using UHPLC-MS-based pseudo-targeted metabolomic profiling, we systematically evaluated overall metabolic modifications in Asian plum fruits in response to GD for the first time. The identified metabolic pathway alterations helped to better understand the internal relationships and related metabolic networks.

Harpephyllum caffrum fruit (wild plum) facilitates glucose uptake and modulates metabolic activities linked to neurodegeneration in isolated rat brain: An in vitro and in silico approach.

Alteration in brain glucose metabolism due to glucose uptake reduction has been described in the onset of certain neurodegenerative disorders. This study determined Harpephyllum caffrum fruit's potential ability to improve glucose uptake and its modulatory effects on intrinsic antioxidant, glucogenic, cholinergic, and nucleotide-hydrolyzing enzyme activities in isolated rat brain. Consequently, the bioactive compounds of the fruits were identified with LC-MS. The fruit significantly improved brain glucose uptake following coincubation with glucose and brain tissue. The fruit extract also elevated GSH level, SOD, catalase, glycogen phosphorylase, and ENTPDase activities while simultaneously suppressing NO and malonaldehyde levels and fructose-1,6-bisphosphatase, ATPase, acetylcholinesterase and butyrylcholinesterase activities. LC-MS analysis revealed S-methylcysteine sulfoxide, dihydroquercetin, 3,4-dimethyl-2,5-bis(3,4,5-trimethoxyphenyl) tetrahydrofuran (MTHF), nobiletin, puerarin, quercetin 3-rutinoside, 8-D-glucosyl-4',5,7-trihydroxyflavone, asperulosidic acid, 1,2,4,6-tetragalloylglucose, and phellamurin. This study suggests the neuroprotective effects of H. caffrum fruit due to its ability to enhance glucose uptake, attenuate glucose-induced oxidative stress while modulating glucogenic, cholinergic, and nucleotide-hydrolyzing enzyme activities in normal brain tissues. PRACTICAL APPLICATIONS: Available scientific evidence describes oxidative stress as one of the physiological processes contributing to aging-associated neurodegeneration in humans. In this regard, commonly consumed natural products from plants have attracted much interest due to their ability to mitigate redox imbalance-related pathologies that affect various organs in the body such as the brain. Harpephyllum caffrum or bush mango is an evergreen plant native to the South African vegetation. The fruit from the plant is consumed locally as food or specifically for improving the nutritional quality of meals as deserts or condiments. While previous findings described the high antioxidant properties of the fruits, this study reported possible mechanisms via which the plant may exhibit ameliorative effects against oxidative stress-related neurological disorders in the brain. Hence, findings from the current work present another justification for the significance of fruits as a safer nutraceutical alternative for therapy in neurological disease management.

Purification of damson plum polyphenol oxidase by affinity chromatography and investigation of metal effects on enzyme activity.

Polyphenol oxidase (PPO) was firstly purified from damson plum as a high antioxidant source. PPO was treated by 0-80% ammonium sulfate precipitation and dialysis. Characterization results were determined for catechol, 4-methyl catechol, pyrogallol and caffeic acid as 0.05 M/pH: 7.2/25 °C; 0.2 M/pH: 4.5/10 °C; 0.01 M/pH: 6.8/5 °C, and 0.2 M/pH: 8.5/10 °C, respectively. Vmax and KM values were calculated for same substrates as 17,219.97 U/(mL*min) and 11.67 mM; 7309.72 U/(mL*min) and 5 mM; 12,580.12 U/(mL*min) and 3.74 mM; 12,100.41 U/(mL*min) and 6.25 mM, respectively. Catechol gave the highest Vmax value among substrates. Affinity purification was performed by using Sepharose 4B-L-Tyrosine-p-aminobenzoic acid and Sepharose 6B-L-Tyrosine-p-aminobenzoic acid. Single bands were approximately observed at 50 kDa for each affinity sample in SDS-PAGE and Native-PAGE. 93.88 and 10.46 purification-folds were obtained for PPO by reference Sepharose-4B and original Sepharose-6B gels. Metal effects upon PPO activity were also investigated due to the importance of enzymatic browning in foods. Cu+2 activation and Fe+2 inhibition were observed with a final metal concentration of 1 mM at 219.66 and 43.18%, respectively. PPO purification from damson plum by affinity chromatography, its characterization, stability evaluation by statistically, and effects of metal ions on damson plum PPO have not been investigated in the literature.

New Insights into the Mechanisms of Polyphenol from Plum Fruit Inducing Apoptosis in Human Lung Cancer A549 Cells Via PI3K/AKT/FOXO1 Pathway.

Recent studies have been found that polyphenols from plums fruits can inhibit the proliferation of multiple cancer cells, while the molecular mechanism was unclear. This study aimed to investigate the molecular mechanism underlying the pro-apoptotic effect of purified plum polyphenols (PPP) on human lung cancer A549 cells. Quercitrin (quercetin-3-O-glucoside, 814.19 ± 40.71 mg/g) was identified as the primary polyphenol in PPP via ultra high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UHPLC-QqQ-MS/MS). PPP showed a strong capacity for inhibiting the proliferation of the A549 cells by inducing apoptosis, which was reflected by an increase in the Bax/Bcl-2 ratio. Additionally, the inhibitory rate of PPP on the A549 cells were higher than that of vitamin C when the treatment dose exceeded 160 µg/mL. Transcriptome analysis suggested that PPP-induced apoptosis was closely associated with regulating the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/forkhead box protein O 1 (FOXO1) pathway in the A549 cells. Subsequently, as an activator of AKT, SC79 was applied to confirm that the inhibition of AKT phosphorylation play an important role in the PPP-induced apoptosis of the A549 cells. These results illustrated the potential of PPP as a dietary compound for the prevention of cancer or for use during chemotherapy.

Developmental stages of peach, plum, and apple fruit influence development and fecundity of Grapholita molesta (Lepidoptera: Tortricidae).

Host plant attributes are essential factors determining the population dynamics of herbivorous insects. The developmental stage of host plants, in particular, may affect the biology of Grapholita molesta (Busck), a possibility that has rarely been examined. Here we assessed the effect of developmental stage of plum, peach, and apple fruits on the development and fecundity performance of G. molesta, along with an examination of the firmness and sugar content of the fruits. Among the fruits collected earliest (May 31), plum and apple were better food sources for G. molesta compared to peach in terms of development, reproduction, and life table parameters. However, despite the higher sugar content in peach, G. molesta larvae showed a lower rate of fruit penetration in peach, probably due to fruit firmness. In the later-collected fruit (June 25), both peach and apple were better than plum, as peach and apple were softer and had higher sugar content. Nevertheless, the penetration rate of larva was still low in peach probably due to pubescence on the fruit surface. Although the plum fruits in the later collection date were softer with higher sugar content, there was a negative impact on the development and reproduction because fruits started to liquefy earlier. In conclusion, the developmental stage of fruits with changes in fruit firmness or sugar content affected the development and reproduction of G. molesta, and apple would be the best food source.

Functional characterization of a gibberellin F-box protein, PslSLY1, during plum fruit development.

Fruit development is orchestrated by a complex network of interactions between hormone signaling pathways. The phytohormone gibberellin (GA) is known to regulate a diverse range of developmental processes; however, the mechanisms of GA action in perennial fruit species are yet to be elucidated. In the current study, a GA signaling gene PslSLY1, encoding a putative F-box protein that belongs to the SLY1 (SLEEPY1)/GID2 (gibberellin-insensitive dwarf2) gene family, was isolated from Japanese plum (Prunus salicina). PslSLY1 transcript abundance declined as fruit development progressed, along with potential negative feedback regulation of PslSLY1 by GA. Subcellular localization and protein-protein interaction assays suggested that PslSLY1 functions as an active GA signaling component that interacts with the ASK1 (Arabidopsis SKP1) subunit of an SCF-ubiquitin ligase complex and with PslDELLA repressors, in a GA-independent manner. By using a domain omission strategy, we illustrated that the F-box and C-terminal domains of PslSLY1 are essential for its interactions with the downstream GA signaling components. PslSLY1 overexpression in wild-type and Arabidopsissly1.10 mutant backgrounds resulted in a dramatic enhancement in overall plant growth, presumably due to triggered GA signaling. This includes germination characteristics, stem elongation, flower structure, and fertility. Overall, our findings shed new light on the GA strategy and signaling network in commercially important perennial crops.

Effect of benzothiadiazole treatment on quality and anthocyanin biosynthesis in plum fruit during storage at ambient temperature.

BACKGROUND: Plums tend to experience a reduction in fruit quality due to ripening and they deteriorate quickly during storage at room temperature. Benzothiadiazole (BTH) is a plant elicitor capable of inducing disease resistance in many crops. In this study, the effect of BTH treatment on fruit ripening, fruit quality, and anthocyanin biosynthesis in 'Taoxingli' plum was investigated. RESULTS: The results showed that BTH treatment could accelerate fruit ripening without affecting the incidence of fruit decay or the shelf life. Benzothiadiazole treatment improved the quality and consumer acceptability of 'Taoxingli' plums during storage by increasing the sweetness, red color formation, and the concentration of healthy antioxidant compounds. The BTH treatment could also effectively promote the biosynthesis of anthocyanin by enhancing the enzyme activities of phenylalanine ammonia-lyase (PAL), dihydroflavonol 4-reductase (DFR), anthocyanidin synthase (ANS), and uridine diphosphate flavonoid 3-O-glucosyltransferase (UFGT) and up-regulating the gene expressions of PsPAL, PsCHI, PsDFR, PsANS, and PsUFGT during storage. CONCLUSION: Benzothiadiazole treatment could be a potential postharvest technology for improving fruit quality and consumer acceptability in harvested plum fruit. © 2020 Society of Chemical Industry.

Isolation of novel citrus and plum fruit promoters and their functional characterization for fruit biotechnology.

BACKGROUND: Promoters that confer expression in fruit tissues are important tools for genetic engineering of fruit quality traits, yet few fruit-specific promoters have been identified, particularly for citrus fruit development. RESULTS: In this study, we report five citrus fruit-specific/preferential promoters for genetic engineering. Additionally, we have characterized a novel fruit-preferential promoter from plum. Genes specifically expressed in fruit tissues were selected and their isolated promoter regions were fused with the GUSPlus reporter gene for evaluation in transgenic plants. Stable transformation in Micro-Tom tomato demonstrated that the candidate promoter regions exhibit differing levels of expression and with varying degrees of fruit specificity. CONCLUSIONS: Among the five candidate citrus promoters characterized in this study, the CitSEP promoter showed a fruit-specific expression pattern, while the CitWAX and CitJuSac promoters exhibited high fruit-preferential expression with strong activity in the fruit, weak activity in floral tissues and low or undetectable activity in other tissues. The CitVO1, CitUNK and PamMybA promoters, while exhibiting strong fruit-preferential expression, also showed consistent weak but detectable activity in leaves and other vegetative tissues. Use of these fruit specific/preferential promoters for genetic engineering can help with precise expression of beneficial genes and help with accurate prediction of the activity of new genes in host fruit plants.

Hydrogen peroxide generated by over-expression of cytosolic superoxide dismutase in transgenic plums enhances bacterial canker resistance and modulates plant defence responses.

H2O2 generated during the oxidative burst, plays important roles in plant defenses responses against pathogens. In this study we examined the role of H2O2 on bacterial canker resistance in transgenic plums over-expressing cytosolic superoxide dismutase. Three transgenic lines (C64, C66 and F12) with elevated levels of H2O2 accumulation showed enhanced resistance against bacterial canker disease caused by Pseudomonas syringae pv. syringae, when compared to the non-transformed control. Analysis of the expression of several genes involved in the plant-pathogen interaction showed that the expression of those involved in SA pathway (pr1 and npr1) and JA (lox3) were activated earlier and transiently in transgenic lines C66 and F12 when compared to the wild type. However, the expression of genes involved in anthocyanin synthesis (chi, chs, f3h, dfr, atcs, myb10) and ethylene (acs) was induced at very low levels whereas it was activated by the pathogen at exaggerated levels in the non-transformed line. These results suggest that resistance observed in transgenic lines over-producing H2O2 is correlated with an early and transient induction of defense genes associated with the SA and JA pathways and inhibition of gene expression associated with ethylene and anthocyanin biosynthesis.

Girled-induced anthocyanin accumulation in red-leafed Prunus cerasifera: Effect on photosynthesis, photoprotection and sugar metabolism.

The feedback regulation of photosynthesis depends on the cooperation of multiple signals, including sugars. Herein, the effect of shoot girdling was monitored on a daily basis for three days in green- and red-leafed Prunus cerasifera plants (GLP and RLP, respectively). The effect of anthocyanin presence was investigated in terms of photosynthesis, sugar metabolism and photoprotection. Net photosynthesis (A390) and stomatal conductance were reduced on the first day at 12:00 only in the girdled GLP (29 and 33 %, respectively). Moreover, the girdled GLP displayed at 12:00 higher sucrose, glucose and fructose concentrations than control leaves. Conversely, girdled RLP showed the first reduction of A390 at 18:00, with no significant differences at 12:00 in sucrose and glucose concentrations. The increased biosynthesis of anthocyanins that was only detected in girdled RLP contributed to lowering the accumulation of hexoses. Overall, these results revealed a sugar-buffering role exerted by anthocyanins that positively influence the feedback regulation of photosynthesis. Moreover, non-photochemical quenching, namely pNPQ, revealed the ability of anthocyanins to photoprotect photosystem II from supernumerary photons reaching the chloroplast, whose function was compromised by girdling. The present study provides a starting point to understand the possible link between photosynthesis regulation through sugar signalling and anthocyanin upregulation.

Physico-Chemical Properties and Oxidative Stability of Fixed Oil from Plum Seeds (Prunus domestica Linn.).

Storage of a great amount of plum kernel waste becomes a challenge for food industry. In this work, the plum seed was used as a source of fixed oil that can be an ingredient of commercial products. Soxhlet extraction was carried out using the different solvents, such as n-hexane, n-heptane, ethyl acetate, acetone, or chloroform:methanol mixture (2:1 v/v). The highest yield of oil (about 30%) was obtained using n-heptane and n-hexane, while the lowest yield was obtained using ethyl acetate. The analysis of physico-chemical parameters indicated that all samples of plum seed oil have an exceptional quality. Schaal oven test indicated that the fixed oil of plum seed exhibited satisfactory oxidative stability at moderate storage temperatures (up to 65 °C). The composition of phenolic compounds in the oil samples was determined using HPLC method. The most abundant compound of seven identified and quantified phenolic compounds was vanillic acid. The highest content of ß-carotene (1.67 mg 100 g-1 fixed oil) spectrophotometrically determined was in the oil extracted with n-hexane. The lowest content of ß-carotene (1.26 mg 100 g-1 fixed oil) was determined in the oil extracted with a mixture of chloroform:methanol (2:1 v/v). This oil had the highest antioxidant activity (IC50 value of 4.35 mg mL-1) compared to other oil samples. The antioxidant activity was probably caused by the presence of phenolic compounds. The investigated physico-chemical properties demonstrated that the plum seed oil has a potential for application in the food, cosmetics, and pharmaceutical industry.

New acylated cyanidin glycosides extracted from underutilized potential sources: Enzymatic synthesis, antioxidant activity and thermostability.

Interest in anthocyanins has increased remarkably in recent decades, although their wider application has been hampered by instability problems. Thus, this study aimed at developing a strategy to gain access to more stable anthocyanins via enzymatic esterification. For that purpose, three cyanidin derivatives were obtained from underutilized, but easily accessible sources, and their total anthocyanin content was quantified. The purity of cyanidins obtained ranged from 40% to 88% depending on their source. Subsequently, the critical enzymatic reaction conditions were established, and the best results were found using tert-butanol as a solvent, 20 g/L of lipase B from Candida Antarctica, and vinyl cinnamate as acyl donor at ratio 250:1 (acyl donor to anthocyanin). Finally, five new acylated anthocyanin derivatives were synthesized with improved antioxidant activity and thermostability, in comparison to the cyanidin-3-glucoside, which is an advantageous feature for industrial applications.

Influence of ultrasound-assisted osmotic dehydration on texture, bioactive compounds and metabolites analysis of plum.

The aim of this study was to investigate the effect of ultrasound-assisted osmotic dehydration on texture, retention of bioactive compounds, nutritional quality and metabolites of plum. The osmotic dehydration was performed using 50% glucose and sucrose in ultrasound (25 kHz) for 30 and 60 min. After osmotic treatment samples were dried at 55 °C using hot air oven. In this study, the texture of the sample was determined by 20% compression of texture profile analysis and solute diffusion coefficient was calculated by Fick's law of diffusion. Further, the volatile compound and nutritional quality were determined. Furthermore, treatment difference of osmo-dehydrated plum on metabolites was measured by 1H NMR. The results showed that the ultrasound-assisted osmotic dehydration increased water loss and solid gain. It also increases the reduction of moisture content from the plum. Textural result of osmo-dehydrated plum in glucose increases the softness of plum and decreases hardness. Moreover, the increased antioxidant and phenolics were obtained in plum treated in 50% sucrose for 30 and 60 min and also at 30 min of glucose. Color of ultrasound-assisted osmotic dehydrated plum was also affected by treatment time and the osmotic solution used. Ultrasound-assisted osmotic dehydration reveals that water loss, solid gain, texture and bioactive compounds affected by treatment time and osmotic solution.

Hormone balance in a climacteric plum fruit and its non-climacteric bud mutant during ripening.

Hormone balance plays a crucial role in the control of fruit ripening. We characterized and compared hormone balance in two Japanese plum cultivars (Prunus salicina Lindl.), namely Santa Rosa, a climacteric type, and Sweet Miriam, its non-climacteric bud-sport mutant. We assessed hormonal changes in gene expression associated with hormone biosynthesis, perception and signaling during ripening on-the tree and throughout postharvest storage and in response to ethylene treatments. Non-climacteric fruit displayed lower ethylene levels than climacteric fruit at all stages and lower auxin levels during the initiation of ripening on-the-tree and during most of post-harvest storage. Moreover, 1-MCP-induced ethylene decrease also resulted in low auxin contents in Santa Rosa, supporting the role of auxin in climacteric fruit ripening. The differences in auxin contents between Santa Rosa and Sweet Miriam fruit could be the consequence of different routed auxin biosynthesis pathways as indicated by the significant negative correlations between clusters of auxin metabolism-associated genes. Ethylene induced increased ABA levels throughout postharvest storage in both ripening types. Overall, ripening of Santa Rosa and Sweet Miriam fruit are characterized by distinct hormone accumulation pathways and interactions.

Changes in secondary metabolites, organic acids and soluble sugars during the development of plum fruit cv. 'Furongli' (Prunus salicina Lindl).

BACKGROUND: Organic acids, sugars and pigments are key components that determine the taste and flavor of plum fruit. However, metabolism of organic acid and sugar is not fully understood during the development of plum fruit cv. 'Furongli'. RESULTS: Mature fruit of 'Furongli' has the highest content of anthocyanins and the lowest content of total phenol compounds and flavonoids. Malate is the predominant organic acid anion in 'Furongli' fruit, followed by citrate and isocitrate. Glucose was the predominant sugar form, followed by fructose and sucrose. Correlation analysis indicated that malate content increased with increasing phosphoenolpyruvate carboxylase (PEPC) activity and decreasing nicotinamide adenine dinucleotide-malate dehydrogenase (NAD-MDH) activity. Citrate and isocitrate content increased with increasing PEPC and aconitase (ACO) activities, respectively. Both acid invertase and neutral invertase had higher activities at the early stage than later stage of fruit development. Fructose content decreased with increasing phosphoglucoisomerase (PGI) activity, whereas glucose content increased with decreasing hexokinase (HK) activity. CONCLUSION: Dynamics in organic acid anions were not solely controlled by a single enzyme but regulated by the integrated activity of enzymes such as nicotinamide adenine dinucleotide phosphate-malic enzyme (NADP-ME), NAD-ME, PEPC, ACO and NADP-isocitrate dehydrogenase. Sugar metabolism enzymes such as PGI, invertase and HK may play vital roles in the regulation of individual sugar metabolic processes. © 2018 Society of Chemical Industry.

Industrial prune processing and its effect on pesticide residue concentrations.

The aim of this study was to determine the insecticide residue processing factor (PF) from plums to prunes and the effect of the industrial processing of prunes residue concentrations. Our results show an increase of insecticide concentrations during plum dehydration that is explained by fruit water loss; however, the normalized insecticide residue concentration, based on plum dry weights to compensate dehydration, was reduced. The water washing and tenderizing of prunes produced insecticide residue reductions of 22.9 ±â€¯4.5% and 21.9 ±â€¯4.2%, respectively. PF were: 1.157, 1.872, 1.316, 0.192, 2.198, 0.775 and 0.156 for buprofezin, l-cyhalothrin, spirodiclofen, indoxacarb, acetamiprid, imidacloprid and emamectin benzoate, respectively, being directly related to water solubility, aqueous hydrolysis and degradation point and inversely related to molecular mass and melting point. In plums for the dehydrated agroindustry the final product is prunes, therefore, it is crucial to consider the PF to determine the specific preharvest interval for this important agroindustry.

Effects of paper containing 1-MCP postharvest treatment on the disassembly of cell wall polysaccharides and softening in Younai plum fruit during storage.

Disassembly of cell wall polysaccharides accompanied with softening is very common in harvested fruits. To develop a facile postharvest approach, which can be used at ambient temperature, for suppressing softening and maintaining higher nutritive cell wall polysaccharides of Younai plums, influences of paper containing 1-methylcyclopropene (1-MCP) on firmness, activities of cell wall-degrading enzymes, and contents of cell wall polysaccharide in Younai plums during storage at 25 ±â€¯1 °C were investigated. As compared to the control plums, 1.2 µL·L-1 1-MCP-treated plums exhibited higher firmness, lower activities of cell wall-degrading enzymes (pectinesterase, polygalacturonase, cellulase and ß-galactosidase), higher contents of cell wall polysaccharides (sodium carbonate-soluble pectin, chelate-soluble pectin, cellulose, and hemicelluloses), and lower content of water-soluble pectin. The results suggested that paper containing 1-MCP, which was convenient to apply under ambient temperature, could significantly inhibit activities of cell wall degrading-enzymes and decrease disassembly of cell wall polysaccharides, and subsequently retard softening in Younai plums.