Search Results (386)

Enzymatic browning, driven by polyphenol oxidase (PPO), remains a major postharvest challenge for potato (Solanum tuberosum L.), reducing product quality, shelf life, and consumer acceptance. To mitigate this trait in the elite tetraploid cultivar ‘Yagana-INIA’, we applied a geminivirus-derived CRISPR–Cas9 system to edit the StPPO genes most highly expressed in tubers, StPPO1 and particularly StPPO2. A paired-gRNA strategy generated a double-cut deletion in StPPO1, while StPPO2 editing required a complementary single-gRNA screening workflow. High-resolution fragment analysis and sequencing identified three StPPO2-edited lines, including one that lacked GFP, Cas9, and Rep/RepA sequences, confirming a transgene-free editing outcome. Edited tubers exhibited visibly reduced browning relative to wild type, and biochemical assays showed decreased PPO activity consistent with targeted disruption of StPPO2. Amplicon sequencing verified monoallelic editing at the gRNA2 site in the non-transgenic line. These results demonstrate the utility of a replicon-based CRISPR system for achieving targeted, transgene-free edits in tetraploid potato and identify a non-GM StPPO2-edited line with improved postharvest quality under Chile’s regulatory framework. Full article

While cold storage is essential to extend the postharvest preservation of litchi fruit, the abrupt transfer to ambient temperature during supply chain transitions may trigger rapid quality degradation. However, the comprehensive mechanisms and critical threshold of post-transfer quality deterioration remain insufficiently characterized. In this study, litchi fruits were stored at 4 °C for 10, 20, and 30 days, followed by simulated shelf life at 25 °C. Key indicators, including appearance quality, antioxidant capacity, lipid peroxidation, and enzymatic oxidation, were monitored, and principal component analysis (PCA) was used to determine quality deterioration thresholds. Litchi subjected to 30 d of cold storage exhibited significantly accelerated pericarp browning compared to those stored for 20 d and 10 d, with the browning index increasing by 25.7% (vs. 20 d) and 41.9% (vs. 10 d), respectively, after 24 h of ambient exposure. This was accompanied by a significant impairment of the antioxidant system. Compared to the fruits stored for 10 d and 20 d, the activities of key antioxidant enzymes (SOD, CAT, and APX) were substantially decreased in the 30 d group, with reductions ranging from approximately 9% to 28%. Concurrently, the non-enzymatic antioxidant capacity also declined. Meanwhile, 30 d of storage activated the browning-related enzymes: anthocyanase and peroxidase (POD) activities increased by 1.2- to 3.6-fold, and poly-phenol oxidase (PPO) activity increased by 11% to 37%, compared to the 10 d and 20 d groups, respectively. In contrast, phenylalanine ammonia lyase (PAL) activity was inhibited by 56.9%. It also enhanced membrane lipid metabolism disorders, which aggravated cell structure damage and oxidative stress. For practical application, PCA identified 10 d (4 °C) + 6 h (25 °C), and 20 d (4 °C) + 12 h (25 °C) as the optimal and critical quality thresholds, respectively. This study reveals the interactive regulatory relationship between cold storage duration and ambient exposure time mediated by oxidative stress, enzymatic browning, and membrane lipid metabolism, providing a theoretical basis for developing time-temperature-quality models to reduce postharvest losses in litchi. Full article

Fusarium oxysporum-induced soft rot severely threatens postharvest pitaya quality and storage life, and while vanillin shows promise in the disease management, its mechanisms for controlling pitaya decay remain incompletely understood. In this study, we systematically investigated the molecular mechanism by which vanillin inhibits soft rot in postharvest pitaya, employing physiological and biochemical characterization, bioinformatics analysis, and molecular biology techniques. Compared with control fruit on 10 d, vanillin treatment significantly reduced disease index and lesion area by 27.12% and 67.43%, respectively. Meanwhile, vanillin treatment delayed the degradation of total soluble solids (TSSs) and titratable acidity (TA) and promoted the accumulation of total phenolics and flavonoids. Additionally, vanillin enhanced the activities of defense-related enzymes, such as catalase (CAT), superoxide dismutase (SOD), phenylalanine ammonia-lyase (PAL), β-1,3-glucanase (GLU), chitinase (CHI), peroxidase (POD) and polyphenol oxidase (PPO), and increased antioxidant capacity, as evidenced by increased DPPH radical scavenging capacity and ascorbic acid content. This resulted in reduced oxidative damage, as indicated by decreased levels of malondialdehyde (MDA), H₂O₂ and O₂^•−. Yeast one-hybrid (Y1H), dual-luciferase reporter (DLR) and subcellular localization revealed that HuTGA1, a nuclear-localized transcriptional activator, specifically bound to the as-1 cis-acting element and activated expression of HuNPR1 and HuNPR5-1. Transient overexpression of HuTGA1 reduced reactive oxygen species (ROS) accumulation and upregulated related genes. These findings suggest that vanillin treatment might enhance pitaya resistance by activating the HuTGA1-HuNPR signaling module, providing insights into the molecular mechanisms underlying vanillin-induced resistance. Full article

Light is a crucial environmental regulator for Tricholoma giganteum (T. giganteum). This study investigated the effects of light quality and photoperiod on its growth, physiology, and nutritional composition. During the mycelial stage, blue light (BL) exposure for 5 d promoted the highest growth rate (0.74 mm d⁻¹, 45% higher than dark control, p < 0.05). Red light (RL) enhanced antioxidant capacity, elevating superoxide dismutase (SOD) activity to 240.20 U·mL⁻¹ (after 5 d) and DPPH radical-scavenging activity to 276.11% (after 3 d). Ultraviolet (UV) suppressed polyphenol oxidase (PPO) activity. BL also increased mycelial polysaccharide content (6.45 g·100 g⁻¹). In the fruiting stage, green light (GL) improved agronomic traits and first-grade yield (3.75 kg), while also promoting the accumulation of glutamate (4.39 g·100 g⁻¹), a key umami compound. Further photoperiod optimization revealed that 4 h of daily GL exposure shortened the fruiting cycle, achieved the highest biological efficiency (98.4%), and maximized both polysaccharide (38.17 g·100 g⁻¹) and glutamate contents (5.70 g·100 g⁻¹). These results recommend a two-stage lighting protocol: BL for mycelial growth and a 4 h daily GL for fruiting, providing a scientific basis for the industrial cultivation of T. giganteum. Full article

This study investigated the mechanism by which combined vacuum packaging and 0.5% (w/v) ascorbic acid treatment (VP-AsA) preserves fresh-cut potatoes at 4 °C, integrating physiological and transcriptomic analyses. Transcriptome sequencing revealed 2246 differentially expressed genes (DEGs) in the VP-AsA group. Notably, key genes involved in glutathione metabolism and NADPH regeneration—encoding glutathione reductase (GR), glutathione S-transferase (GST), isocitrate dehydrogenase (IDH), glucose-6-phosphate dehydrogenase (G6PDH), and ornithine decarboxylase (ODC)—were significantly up-regulated. This transcriptional reprogramming, which was associated with increased glutathione (GSH) content, provides a molecular basis for the enhanced antioxidant capacity observed in the treated samples, including elevated superoxide dismutase (SOD) activity, DPPH/ABTS radical scavenging capacity, and ferric reducing antioxidant power (FRAP). Concurrently, VP-AsA treatment reduced water migration, inhibited polyphenol oxidase (PPO) and peroxidase (POD) activities, and maintained key textural properties (hardness, fracturability, springiness, chewiness) during the first 9 days of storage. These results suggest that VP-AsA treatment preserves quality at least in part by transcriptionally activating glutathione-mediated antioxidant pathways, providing insights for fresh-cut fruits and vegetables quality control. Full article

Postharvest storage and quality maintenance represent significant constrains for the marketability and long-distance exportation of button mushroom (Agaricus bisporus). Protective techniques such as arginine application has been demonstrated to extend the shelf life of button mushroom. However, the underlying mechanism by which arginine mitigates postharvest softening in button mushroom require further elucidation. In this study, comprehensive physiology, metabolomics and transcriptomics analyses of button mushroom following arginine treatment were conducted to investigate its potential mechanisms of action. Physiological analysis showed that arginine treatment (1.5 g L⁻¹) markedly alleviated the postharvest softening of button mushroom, resulting in a 23.8% increase in firmness, reduced malondialdehyde (MDA) content, suppressed activities of phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO), and maintained elevated superoxide dismutase (SOD) activity. Integrated transcriptomic and metabolomic analyses demonstrated that arginine application significantly altered lipid-related metabolites, including free fatty acids, lysophosphatidylcholine (LPC), lysophosphatidylethanolamine (LPE) and phosphatidylcholine (PC). Notably, arginine treatment increased the levels of unsaturated fatty acids (UFAs). Transcriptomic analysis further revealed that differentially expressed genes (DEGs) were predominantly enriched in lipid metabolism pathways following arginine treatment. Specifically, arginine application stimulated the lipid metabolism by upregulating genes associated with fatty acid desaturation (FAD), while downregulating genes related to phospholipases A2 (PLA2). These findings collectively demonstrate that arginine effectively mitigates postharvest softening of button mushroom by modulating lipid metabolism. Full article

The polyphenol oxidase (PPO) enzyme leads to undesirable consequences by causing enzymatic browning during the processing of vegetables and fruits. As these browning reactions occur, many phenolic compounds of PPO can lead to significant changes in active metabolites due to substrate utilization. This may cause a loss of appearance and nutritional and commercial value of food. The sickleweed (Falcaria vulgaris Bernh.) plant studied in the current research is considered an edible and medicinal food. In the present research, polyphenol oxidase was purified 15.65-fold with a yield of 23.61% by affinity chromatography. The optimum pH and temperature for catechol, 4-methylcatechol, and 3,4-dihydroxyphenylpropionic acid substrates were determined in separate experiments. For all three substrates, the optimum pH was 7.0, while the optimum temperature was 20 °C. The catalytic efficiency ratio (V_max/K_m) was employed to assess the substrate specificity. Since the highest V_max/K_m ratio reflects the greatest substrate affinity, 4-methylcatechol was identified as the substrate with the highest affinity for sickleweed PPO based on these values. pH stability and thermal stability were examined in the presence of 4-methylcatechol. The inhibitory effects of widely used antibrowning agents, sodium metabisulphite, citric acid, and ascorbic acid, on PPO activity were investigated. The results show that ascorbic acid was the most efficient inhibitor. Full article

In this study, we aimed to elucidate the mechanism through which treatment with slight water loss combined with methyl jasmonate (MeJA) regulates gray mold development in Actinidia arguta, focusing on reactive oxygen species (ROS) and phenylpropanoid metabolism. The results showed that water loss alone, MeJA alone, and their combination each reduced the incidence of disease, with the combined treatment showing the greatest efficacy. At the end of the storage period, the combined treatment enhanced the activities of superoxide dismutase (SOD), polyphenol oxidase (PPO), peroxidase (POD), phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H), and 4-coumarate-CoA ligase (4CL). It also increased the accumulation of defense-related substances (total phenol and lignin contents) and up-regulated AaPAL, Aa4CL, AaC4H, and AaC3′H gene expression. Furthermore, the combined treatment reduced the disease severity index from 60% to 16% and delayed onset by 2 d. In conclusion, slight water loss combined with MeJA treatment effectively suppressed gray mold. This effect may be attributed to activation of ROS metabolism, induction of phenylpropanoid metabolism, and up-regulation of related genes, which enhanced the resistance of the fruit to gray mold. Full article

Polyphenol oxidase (PPO) is the primary biochemical driver of browning and the subsequent decline of market quality in harvested fruit. In this work, a fully non-invasive analytical framework was built using Visible/Near-Infrared (VIS/NIR) spectroscopy coupled with chemometric modeling in order to estimate PPO activity in two commercially relevant plum cultivars (Khormaei and Khoni). A comprehensive comparative study was conducted utilizing multiple machine learning and linear regression techniques, including Support Vector Regression (SVR), Decision Tree (DT), and Partial Least Squares Regression (PLSR). After acquiring the full VIS/NIR spectra, a suite of metaheuristic feature selection strategies was applied to compress the spectral space to roughly 10–15 highly informative wavelengths. SVR, DT, and PLSR models were then trained and benchmarked using (a) the complete spectral domain and (b) the reduced wavelength subsets. The results consistently demonstrated that non-linear models (DT and SVR) significantly outperformed the linear PLSR method, confirming the inherent complexity and non-linearity of the relationship between the spectra and PPO activity. Across all tests, DT consistently produced the strongest generalization. Under full spectra inputs, DT reached RPD values of 4.93 for Khormaei and 5.41 for Khoni. Even more importantly, the wavelength-reduced configuration further enhanced performance while substantially lowering computational cost, yielding RPDs of 3.32 (Khormaei) and 5.69 (Khoni). The results show that VIS/NIR combined with optimized key-wavelength DT modeling provides a robust, fast, and field-realistic route for quantifying PPO activity in plums without physical destruction of the product. Full article

Bougainvillea spectabilis ‘Yunnan Purple’ is a relatively cold-tolerant variety, but its low pollen viability and poor seed set have limited large-scale reproduction. To establish an efficient propagation protocol, cuttings from three types of Bougainvillea spectabilis ‘Yunnan Purple’ were treated with varying concentrations of exogenous indole-3-butyric acid (IBA). Rooting parameters, growth indicators, and physiological metrics were measured, and the optimal treatment was identified through comprehensive membership function evaluation. The results showed that cutting types significantly influenced rooting, root development, plant growth, organic compound content (soluble sugars, starch, and protein), and abscisic acid (ABA) content. Conversely, IBA concentration significantly affected rooting, root architecture, polyphenol oxidase (PPO) activity, and the levels of indole-3-acetic acid (IAA) and Brassinolide (BR). This comprehensive evaluation identified lignified shoots (LS) treated with 100 mg/L IBA (LS-100) as the optimal protocol, which achieved a rooting rate of 63% and significantly improved root formation, plant growth, root activity, organic compound content, PPO activity, and the levels of IAA and BR. This study provides valuable insights and technical guidance for the large-scale cutting propagation of Bougainvillea spectabilis ‘Yunnan Purple’. Full article

Vegetable soybean is a major crop in China with significant economic value. However, it is prone to yellowing and browning during postharvest storage, which reduces quality, marketability, and competitiveness. ‘Tongdou No. 6’ was used to evaluate postharvest quality preservation through combined cold shock treatment and nanocomposite polymer packaging. The results demonstrate that the combined treatment effectively slows the green-to-yellow color change by significantly reducing chroma a* value, weight loss, and chlorophyll degradation. Additionally, it markedly reduces the accumulation of malondialdehyde (MDA) and reactive oxygen species (H₂O₂ and O₂·⁻), while decreasing the activities of polyphenol oxidase (PPO) and peroxidase (POD). The treatment also significantly enhanced the levels of antioxidant compounds, including ascorbic acid (AsA), total phenolics, and total flavonoids, and boosted the activities of key antioxidant enzymes—ascorbate peroxidase (APX), superoxide dismutase (SOD), phenylalanine ammonia-lyase (PAL), and catalase (CAT). Moreover, the combined application of cold shock and nanocomposite polymer packaging significantly enhanced the scavenging capacity against DPPH and hydroxyl (OH⁻) radicals. Overall, combining these two techniques effectively delayed senescence-related discoloration by activating the antioxidant system, regulating ROS metabolism, and reducing oxidative damage. This approach is highly effective in maintaining postharvest quality and offers a promising solution to the storage-induced deterioration of vegetable soybeans. Full article

An increasing trend toward alternative methods in grapevine protection is evident, diverging from conventional chemical approaches. Biostimulants, such as chitosan hydrochloride, are compounds able to elicit the synthesis of plants’ metabolites, leading to an increase in their natural defence mechanism. Some of these metabolites could potentially impact wine sensory properties such as colour, mouthfeel, and aroma. This study investigates the effect of chitosan hydrochloride treatment on Sauvignon blanc vines, isolating impacts on plant, grape, and wine levels. Using a randomized block design with 74 potted plants grown in a glasshouse, the study found that foliar chitosan application did not affect plant growth or phenolic compound accumulation in the leaves. Conversely, it significantly decreased polyphenol oxidase (PPO) activity and increased antioxidant activity and polyphenolic content in grape berries. Treated berries exhibited doubled protein content, less thaumatin-like proteins, and more β-glucanases and chitinases than control grapes. Microvinifications revealed that wines from treated grapes had higher total polyphenols, polysaccharides, Abs 320 nm values, and total proteins than control wines. These preliminary results suggest that chitosan application affects key grape metabolites with potential implications for wine quality, warranting further investigation. Full article

Experimental studies published to date on the effects of silver nanoparticles (AgNPs) on plants have yielded highly contradictory results: reported outcomes range from growth inhibition to stimulation. The objective of this research was to test the hypothesis that the ontogenetic stage at the time of exposure to AgNPs is a key determinant of both the qualitative profile and quantitative magnitude of plant responses. For this purpose, laboratory seed priming and small-plot field experiments with wheat plants (Triticum aestivum L.) treated with stabilized dispersions of AgNPs at 1–100 mg∙L⁻¹ were conducted. It was shown that seed priming with low concentrations of AgNPs (1–5 mg∙L⁻¹) did not affect wheat seedling growth, whereas dispersions at ≥25 mg∙L⁻¹ suppressed development. In agreement, antioxidant enzyme activities (POD, CAT, PPO) increased at 1–5 mg·L⁻¹ and decreased at 100 mg·L⁻¹. By contrast, foliar treatments of field-grown wheat increased plant population density, plant height, spike structure metrics, and grain yield. The optimal regimen—three foliar applications at 5 mg·L⁻¹—increased grain yield by 12.1% from 5.89 t·ha⁻¹ to 6.60 t·ha⁻¹. At low doses of AgNPs, activities of peroxidase, catalase, and polyphenol oxidase in seedlings tissues increased, indicating activation of nonspecific defense mechanisms; at higher concentrations, activities of these enzymes decreased, indicating antioxidant system exhaustion and dysfunction. The findings demonstrate dose- and stage-dependent effects and corroborate the central role of the developmental stage of wheat in determining responses to AgNPs, indicating opportunities to optimize stage-aware, low-dose application regimes to enhance productivity while minimizing phytotoxic risk. Full article

Adventitious rooting is a key step for the clonal propagation of many economically important horticultural and woody species. Accumulating evidence suggests that nitric oxide (NO) serves as a key signaling molecule with key roles in root organogenesis. However, the role of NO in adventitious root development and its underlying mechanism in sweetpotato cuttings remain to be clarified. In this study, a pot experiment was conducted using hydroponically cultured sweetpotato cuttings (Ipomoea batatas cv. ‘Jin Ganshu No. 9’) treated with different concentrations of sodium nitroprusside (SNP, an NO donor) solution (0, 10, 50, 100, 200, and 500 μmol·L⁻¹). Three treatments were established: Control, SNP (the optimal concentration of SNP), and SNP + 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO, an NO scavenger). The results showed that NO promoted adventitious rooting in a dose-dependent manner, with the maximal biological response observed at 100 μM SNP. At this concentration, the root number and length of adventitious roots increased by 1.22 and 2.36 times, respectively, compared to the control. SNP treatment increased fresh root weight, dry root weight, the content of soluble sugar, soluble protein, chlorophyll a (Chl a), chlorophyll b (Chl b), and total chlorophyll (a + b) [Chl(a + b)], as well as the activities of peroxidase (POD), polyphenol oxidase (PPO), and indole acetic acid oxidase (IAAO). It also enhanced the levels of maximum fluorescence (Fm), maximum photochemical efficiency of photosystem II (Fv/Fm), absorbed light energy (ABS/RC), trapped energy flux (TRo/RC), and electron transport flux (ETo/RC), while decreasing starch content and initial fluorescence (Fo). On the 7th day, the SNP treatment significantly enhanced several biochemical parameters compared to the control. We observed an increase in many of the parameters: POD activity by 1.35 times, PPO activity by 0.55 times, chlorophyll content (Chl a by 0.66 times, Chl b by 0.22 times, and Chl a + b by 0.57 times), and photosynthesis parameters by 28–98%. Meanwhile, starch content and Fo in the SNP treatment decreased by 10.77% and 23.86%, respectively, compared to the control. Furthermore, the positive effects of NO on adventitious root development and associated biochemical parameters were reversed by the NO scavenger cPTIO. Additionally, significant and positive correlations were observed between morphological characteristics and most physiological indicators. Collectively, these results demonstrate that NO promotes adventitious root formation, which may be by enhancing rooting-related enzyme activities, improving photosynthetic performance in leaves, and accelerating the metabolism of soluble sugar, soluble protein, and starch. Full article

Phoebe bournei is an important economic tree species in China, its large-scale propagation is limited by the difficulty of adventitious root (AR) formation in cuttings. In this study, morphological, physiological, and transcriptomic analyses were conducted to investigate the process of AR formation in P. bournei. The results showed that ARs mainly originated from callus tissue. During AR formation, soluble sugar and soluble protein contents changed significantly. Malondialdehyde (MDA) and oxygen free radicals (OFRs) peaked at first sampling stage (PB0), while the activities of polyphenol oxidase (PPO) and indoleacetic acid oxidase (IAAO) exhibited similar patterns. Lignin content increased during callus induction stage, whereas phenolic content continuously declined throughout rooting. Endogenous hormone levels also changed markedly, and Orthogonal partial least squares discriminant analysis (OPLS-DA) analysis indicated that indole-3-acetic acid (IAA) and abscisic acid (ABA) played dominant roles in this process. KEGG enrichment analysis revealed significant enrichment of the phenylpropanoid biosynthesis pathway in all three comparison groups. A total of 48 differentially expressed genes (DEGs) were enriched in plant hormone signal transduction pathways, with 22 and 14 genes associated with IAA and ABA signaling, respectively. Weighted gene co-expression network analysis (WGCNA) further identified two hub modules related to IAA and ABA contents, including eight hub genes such as D6PKL1 and ISTL1. Correlation analysis revealed that the hub genes D6PKL1 and HSP were significantly positively correlated with IAA4 in the IAA signaling pathway. Overall, this study provides new insights into the mechanisms underlying AR formation in P. bournei cuttings and offers a theoretical basis for optimizing its clonal propagation system. Full article