Accumulation Of Phenolics Research Articles

Enhancement of in vitro production of tropane alkaloids and phenolic compounds in Hyoscyamus niger by culture types and elicitor treatments

This study aimed to determine the effects of 24-epibrasinolide (EBL) and methyl jasmonate (MJ) treatments on growth parameters and secondary metabolite synthesis in adventitious root and cell suspension cultures of Hyoscyamus niger. Therefore, different concentrations (0.5, 1 and 2 mg L−1) of EBL alone and combined with 224.3 mg L−1 (1 mM) MJ were applied to root and cell suspension cultures. 2 mg L−1 and 1 mg L−1 EBL were determined as the treatments in which the highest values were obtained in terms of growth criteria in root and cell cultures, respectively. In root cultures, the highest scopolamine accumulation (2.57 mg g−1) was obtained from the combination of 2 mg L−1 EBL and MJ, while the highest value (0.66 mg g−1) for hyoscyamine was observed in the roots treated with 1 mg L−1 EBL and MJ. In cell cultures, 2 mg L−1 EBL for scopolamine and 0.5 mg L−1 EBL for hyoscyamine were found to be the best applications and calculated as 0.51 µg g−1 and 0.28 µg g−1, respectively. EBL and MJ treatments also stimulated total phenolic content (TPC). The highest TPC in root cultures was detected as 18.01 mg g−1 with the combination of MJ while in cell cultures, maximum TPC was observed in cells applied with 2 mg L−1 EBL and MJ as 11.56 mg g−1. When EBL and MJ were applied to root and cell suspension cultures, significant changes occurred in the amount of phenolic compounds. Co-application of EBL and MJ significantly increased the amount of gallic acid, catechin, epicatechin, cinnamic acid and chlorogenic acid in root cultures. The application of 2 mg L−1 EBL was determined as the most suitable application for gallic acid, catechin, epicatechin, p-coumaric acid, and caffeic acid in cell cultures. It was also found that the metabolite production performance of adventitious roots was higher than that of cells. In conclusion, it was suggested that the use of MJ and EBL may be a promising strategy to enhance the accumulation of scopolamine, hyoscyamine and phenolics in root and cell cultures of H. niger.

Melatonin alleviates UV-B stress and enhances phenolic biosynthesis in rosemary (Rosmarinus officinalis) callus.

Although used in in vitro culture to boost secondary metabolite production, UV-B radiation can seriously affect plant growth if not properly dosed. Rosemary callus can be used as an important source of effective ingredients in the food and medicine industry. To balance the positive and negative effects of UV-B on rosmary callus, this study investigated the effects of melatonin on rosemary callus under UV-B radiation. The results showed that melatonin improved rosemary callus growth, with fresh weight and dry weight increased by 15.81% and 8.30%, respectively. The addition of 100 μM melatonin increased antioxidant enzyme activity and NO content in rosemary callus. At the same time, melatonin also significantly reduced membrane lipid damage and H2O2 accumulation in rosemary callus under UV-B stress, with malondialdehyde (MDA) and H2O2 contents reduced by 13.03% and 14.55%, respectively. In addition, melatonin increased the total phenol and rosmarinic acid contents in rosemary callus by 19% and 54%, respectively. Melatonin significantly improved the antioxidant activity of the extracts from rosemary callus. These results suggest that exogenous melatonin can alleviate the adverse effects of UV-B stress on rosemary callus by promoting NO accumulation while further enhancing phenolic accumulation and biological activity.

Differential accumulation of phenolics and phytoalexins in seven Malus genotypes cultivated in apple replant disease-affected soil

Apple replant disease (ARD) is a globally recognised soil-borne disease, which affects apple orchards and tree nurseries. Biotic factors are considered to be the main causal agent of ARD. Phenolics and phytoalexins were induced in apple roots grown in ARD soil compared to roots grown in disinfested ARD soil. However, the relationship between ARD susceptibility and production of phenolics and phytoalexins in apple roots is still unclear. To answer this question, we cultivated seven Malus genotypes with varying levels of ARD susceptibility (M.26, EMR 2, M.200, G.214, G.935, Selection 4, and MAL0739) in both ARD soil from Heidgraben, Germany, and the same soil after disinfestation by gamma-irradiation (γ-ARD). Despite the overall growth reduction observed for all seven genotypes, three of them, EMR 2, G.935 and MAL0739, showed better performance, as indicated by the ARD susceptibility index (ASI) and differences in their root structure. Phenolics and phytoalexins were differentially induced in the roots grown for four weeks (T4) and eight weeks (T8) in ARD soil compared to γ-ARD soil. Moreover, differences in the total phenolics content (TPC) and the total phytoalexin content among the evaluated Malus genotypes were observed. The biochemical data from the early time point (T4) separated Malus genotypes more effectively compared to that from the late time point (T8). Among the six ARD-induced phytoalexins, 3-hydroxy-5-methoxybiphenyl at T4 can serve as an early biomarker for ARD. Although TPC and total phytoalexin content of the Malus genotypes exhibited no or weak correlation with root and shoot growth reduction, some individual phenolics and phytoalexins showed higher coefficients, suggesting that they might influence the ARD susceptibility of apple rootstocks.

Establishment and elicitation of liquid adventitious root cultures of Inula crithmoides L. for increased caffeoylquinic acids production and hepatoprotective properties

This study established a liquid adventitious root culture for Inula crithmoides L. focusing on producing extracts rich in hepatoprotective caffeoylquinic acids through elicitation. Adventitious roots were induced from in vitro-grown plant leaves cultured on MS medium supplemented with 1 mg/L IBA. Growth and secondary metabolites accumulation (phenolics, flavonoids, hydroxycinnamic acids) were monitored weekly to determine the optimal harvesting time. Then, the adventitious roots were elicited for 4 weeks with varying concentrations of yeast extract–YE (50, 100 and 200 mg/L) and extracted with ethanol. The extracts were evaluated for their hepatoprotective effects against ethanol-induced hepatotoxicity and analyzed through high-performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC–ESI–MS/MS). Roots of greenhouse-cultivated plants were used to compare the results obtained from in vitro -grown adventitious roots. IBA supplementation induced 100% adventitious root formation, with maximum biomass and phenolic accumulation after 4 weeks. Hydroxycinnamic acid levels increased significantly with YE treatment at all the concentrations, particularly in case of chlorogenic acid and di-O-caffeoylquinic acid isomers. The root extracts displayed significant in vitro hepatoprotective effects, particularly at 50 mg/L YE elicitation. Overall, the elicitation of I. crithmoides liquid root cultures with yeast extract offers a promising, efficient, and cost-effective approach for optimizing the production of valuable caffeoylquinic acids having potential pharmaceutical use.

Exploitation of the biocontrol potential of a marine-derived Bacillus velezensis and its application on postharvest strawberry

Fresh strawberry fruits have a significant postharvest diseases incidence and economical losses. To explore more effective postharvest management instruments, a strain of Bacillus velezensis 12Y with excellent antagonistic activity was isolated from the Nanhai Sea. Its whole genome and activity against fruit fungal pathogens was studied. The genomic sequencing revealed that 12Y contains an abundance of functional gene related to biocontrol and biosynthetic gene clusters of secondary metabolites with potential antimicrobial properties. In the strawberry preservation experiment, 12Y fermentation broth (YFB) could effectively reduce the natural decay and extend shelf life of strawberry by delaying the decline of total soluble solids and titratable acid with no adverse effects on weight loss and hardness. Moreover, YFB could enhance the activity of key enzymes in phenylpropanoid metabolism pathway, induce the accumulation of anthocyanin and total phenols, delay the decrease of antioxidant capacity, and reduce the peroxidation of strawberry cell membranes. This study demonstrated the potential of B. velezensis 12Y as an excellent biocontrol bacteria and a promising preservation agent for strawberry.

Surface accumulation and acid-base equilibrium of phenol at the liquid-vapor interface.

We have investigated the surfactant properties of phenol in aqueous solution as a function of pH and bulk concentration using liquid-jet photoelectron spectroscopy (LJ-PES) and surface tension measurements. The emphasis of this work is on the determination of the Gibbs free energy of adsorption and surface excess of phenol and its conjugate base phenolate at the bulk pKa (9.99), which can be determined for each species using photoelectron spectroscopy. These values are compared to those obtained in measurements well below and well above the pKa, where pure phenol or phenolate, respectively, are the dominant species, and where the Gibbs free energy of adsorption determined from surface tension and LJ-PES data are in excellent agreement. At the bulk pKa the surface-sensitive LJ-PES measurements show a deviation of the expected phenol/phenolate ratio in favor of phenol, i.e., an apparent upward shift of the at the surface. In addition, the Gibbs free energies of adsorption determined by LJ-PES at the bulk pKa for phenol and phenolate deviate from those observed for the pure solutions. We discuss these observations in view of the different surface propensity of phenol and phenolate as well as potential cooperative interactions between them in the near-surface region.

Assessment of salt and drought stress on the biochemical and molecular functioning of onion cultivars.

Salt and drought stress are the main environmental constraints that limit onion growth and productivity. Türkiye is the fifth largest onion producer, whereas the stress conditions are increasing in the region, resulting in poor crop growth. A current study was conducted under greenhouse conditions according to a completely randomized design with factorial arrangements to evaluate the performance of onion cultivars. Plants were subjected to salt stress with an application of 750 mM NaCl and drought stress was applied by depriving plants of irrigation water for 20 days to measure biochemical and transcript changes. The antioxidant activities of the cultivars were quantified by using four different methods, i.e., 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assays, cupric reducing antioxidant capacity, 2,2-Diphenyl-1-picrylhydrazyl, and ferric reducing antioxidant power (FRAP). The damage to pigments, phenolic, osmolytes, and hydrogen peroxide (H2O2) accumulation was also evaluated. Results revealed that the cultivars "Elit and Hazar" had higher H2O2, maximum damage to pigments, and least accumulation of phenolics and osmolytes under both stress conditions. The cultivar "Şampiyon" performance was better under salt stress but exhibited a poor antioxidant defensive mechanism under drought stress conditions. The remaining cultivars suggested a resilient nature with a higher accumulation of osmolytes, antioxidants and phenolics. The change in transcript levels further strengthened the response of resilient cultivars; for instance, they showed higher transcript levels of superoxide dismutase, ascorbate oxidase and transcription factors (WRKY70, NAC29). It helped alleviate the oxidative stress in tolerant cultivars and maintained the physio-biochemical functioning of the cultivars.. The results of the current study will fill the gap of missing literature in onion at biochemical and molecular levels. Additionally, resilient cultivars can effectively cope with abiotic stresses to ensure future food security.

Reshaping yeast metabolism and enhancing the quality of fresh-style red wine through low-temperature fermentation

Fresh-style red wine is attracting consumers, prompting an exploration of low-temperature winemaking techniques for its industrial production. Herein, low temperatures were applied to red winemaking, evaluating metabolite compositions and sensory profiles of wines fermented at lower versus higher temperatures. The accumulation of various phenolics at different temperatures may work synergistically with temperatures to shape yeast metabolism. Low temperatures significantly weakened the extraction of phenolic compounds, thus attenuating the bitterness and astringency of wine and contributing better balance and brighter color to wines at lower temperatures. Esters, especially ethyl acetate (increased by 24.8%), ethyl hexanoate (increased by 72.3%), ethyl octanoate (increased by 67.9%), and ethyl decanoate (increased by 50.6%) increased with decreasing temperatures, contributing fresh red fruit aromas to wines fermented at 10 °C, while phenylethanol (decreased by 60.0%) decreased with decreasing temperatures, weakening floral aromas to wines at 10 °C. Low temperatures can reduce higher alcohols (19.3% in total) and positively influence the sensory quality of wine. In general, wines fermented at 10 °C exhibited the highest overall quality, highlighting the potential of low-temperature fermentation in the production of fresh-style red wine.

Role of silica nanoparticles in enhancing drought tolerance of cereal crops

Cereal crops are essential for providing essential nutrients and energy in the daily human diet. Additionally, they have a crucial role as a significant constituent of cattle feed, hence enhancing meat production. Drought, being an abiotic stressor, adversely affects the growth and yield of numerous crops on a global scale. This issue poses a significant and pressing obstacle to maintaining global cereal crop production and ensuring food security. Nanoparticles have become a valuable resource for improving cereal crop yield and productivity under ongoing rapid climate change and escalating drought conditions. Among these, silica nanoparticles (SiNPs) have demonstrated their potential for agricultural applications in regions with limited water availability. Drought stress has detrimental effects on cereal crops, impacting their growth, metabolic, and physiological processes, hampering water and nutrient absorption, disrupting cellular membranes, damaging the photosynthetic apparatus, and reducing antioxidant activities by altering gene expression. SiNPs help preserve cellular membranes, regulate water balance, and improve water and nutrient absorption, resulting in a substantial enhancement in plant growth under water-deficit conditions. SiNPs also protect the photosynthetic system and enhance its efficiency, facilitate the accumulation of phenolics, hormones, osmolytes, antioxidant activities, and gene expression, thus empowering plants with increased resistance to drought stress. Moreover, SiNPs decrease leaf water loss by promoting stomatal closure, primarily by fostering the accumulation of abscisic acid (ABA) and mitigating oxidative stress damage by activating the antioxidant defence system and reducing reactive oxygen species (ROS). However, a limited number of studies examine the role of SiNPs in cereal crops under drought stress conditions. In this review, we highlighted the promising potential of SiNPs to improve cereal crop resilience by changing morpho-histological traits, antioxidant properties, and gene expression to maintain food security in drought-prone areas. This study will aid researchers in using SiNPs as an environmentally benign way to improving drought resistance in cereal crops in order to fulfill global food supply needs.

Calcium chloride treatment maintains quality and enhances antioxidant capacity of fresh-cut carrots through modulating DcCMLs-DcCAMTA3-mediated phenylpropanoid pathway

Whitening and microbial infection are two major reasons to induce quality deterioration in fresh-cut carrots. Calcium chloride (CaCl2) could enhance the quality attributes in fresh-cut carrots, but the molecular mechanism is still not illuminated. In this study, CaCl2 treatment suppressed the increases of whiteness index and total bacterial count as well as enhanced the antioxidant capacity of fresh-cut carrots. In addition, CaCl2 treatment promoted phenolics accumulation by upregulating the transcripts and enzyme activity of phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H) and 4-coumarate coenzyme A ligase (4CL) in phenylpropanoid pathway. However, this treatment inhibited the increase of enzyme activity and gene expression of cinnamyl alcohol dehydrogenase (CAD), thus suppressing lignin synthesis and whitening process in fresh-cut carrots. Moreover, a calmodulin-binding transcription activator (CAMTA) transcription factor DcCAMTA3, was induced in response to CaCl2 treatment. DcCAMTA3 activated the transcription of DcPAL1, DcC4H and Dc4CL1 genes and repressed the expression of DcCAD1 gene by directly targeting the CG-box. DcCML3/11, a calmodulin-like protein, interacted with DcCAMTA3, and this interaction enhanced DcCAMTA3-mediated transcriptional activation of DcPAL1, DcC4H and Dc4CL1 and repression of DcCAD1. Therefore, CaCl2 treatment is effective in maintaining quality and enhancing antioxidant capacity of fresh-cut carrots by the cooperative action of DcCMLs and DcCAMTA3 in positively regulating phenylpropanoid pathway.

Decomposition of lignin and carbohydrates in a rewetted peatland: a comparative analysis of surface water and anaerobic soil layers

The rewetting of long-term drained peatlands leads to the development of eutrophic shallow lakes, gradually inhabited by reed communities. These shallow lakes are characterized by significant nutrient and methane emissions. To comprehend the fate of organic compounds from decaying Phragmites australis litter in water and anaerobic soil layers, we conducted a 1.6-year decomposition experiment. The experiment employed bulk and lignin-derived phenol analysis, as well as Fourier-transform infrared spectroscopy. As anticipated, the highest level of decomposition was observed in the surface water body of the shallow lake, while the non-rooted degraded peat exhibited the lowest decay. The bulk mass loss of plant litter decreased with depth from 55 to 27% across the four decomposition environments. Analysis using infrared spectroscopy indicated that the decrease in mass loss was primarily driven by the breakdown of carbohydrates, which constitute a significant portion of plant litter. Interestingly, litter in the rooted degraded peat layer exhibited the highest degree of lignin decay. Furthermore, the study revealed a preferential loss of vanillin phenols and an accumulation of p-hydroxyl phenols. These findings suggest that the increased methane emissions in rewetted fens may be partially attributed to the demethoxylation of vanillin phenols and the subsequent formation of p-hydroxyl phenols. In conclusion, this study provides valuable insights into anaerobic lignin decomposition of plant litter and sheds light on potential mechanisms underlying elevated methane emissions in rewetted peatlands. Furthermore, the study’s findings hold significant implications for both carbon cycling and sequestration within these ecosystems, thereby stimulating further research into the microbial community and its extended effects.

Enhanced antioxidant activity and quality of olecranon peach fruits (Prunus persica L.) through synergistic application of exogenous nano-selenium and melatonin

Olecranon peach, a significant economic crop in southern China, faces quality degradation due to pests, diseases, and pesticide residues. Melatonin (MT) and nano-selenium (Nano-Se) applied individually have been found to improve crop growth and abiotic stress resistance. However, the impact of different Nano-Se and MT ratios on olecranon peach quality remains uncertain. Plants were foliar sprayed with varying Nano-Se and MT ratios during the fruit set phase. A combined 5 mg/L Nano-Se and 10 mg/L MT (Nano-Se5 + MT10) effect outperformed individual treatments and the control in enhancing fruit quality. Nano-Se5 + MT10 notably increased peroxidase (190.3%) and superoxide dismutase (112.2%) activities, and reduced polyphenol oxidase activity (-13.2%), raised total sugars (33.3%), soluble protein (18.5%), and phenolic contents like apigenin (51.9%), vanillic acid (21.4%), ferulic acid (29.4%), and p-hydroxybenzoic acid (317.2%) compared to the control. Correlation analysis linked antioxidant enzymes and phenolics in olecranon peach fruits to nutrient accumulation. Nano-Se5 + MT10 improves sweetness and quality by enhancing antioxidant ability (increased peroxidase and superoxide dismutase, decreased polyphenol oxidase and phenolics), and promoting soluble protein, total sugar, and phenolic accumulation. In conclusion, Nano-Se5 + MT10 application shows promise in enhancing olecranon peach quality and antioxidant attributes.Graphical

Management of Biosynthetic Potential of Aseptic Plants and Callus Cultures of Ocimum basilicum L. In Vitro

Callus cultures and microclones of sweet basil (Ocimum basilicum L.) were obtained in vitro and their growth and biochemical characteristics were studied depending on the hormonal composition of the MS medium as well as on the addition of zinc ferrate nanoparticles (NPs) to the nutrient medium. During clonal micropropagation of samples, the advantage of various options for the composition of nutrient media was noted: adding NAA to the MS medium for the cultivars Lyubimchik and Vasilisk, IBA for the cultivar Fioletovy barkhat and the species sample from Germany, and IAA for species samples from Poland and Italy. It should be noted that plants of the purple-leaved cultivar Fioletovy barkhat preferred MS medium containing mineral salts at a concentration of ½ normal. The results of the study confirmed the hypothesis put forward by various authors about the ability of microplants and basil callus cells to accumulate secondary metabolites as well as the possibility of controlling this process with the help of biological (mineral and hormonal composition of the nutrient medium) and physical (NP) elicitors. It was shown that the presence of zinc ferrate NPs in the MS medium contributed to the formation of callus tissue of different types of density and color. The addition of 25 μg/L NPs to the MS medium significantly increased the fresh biomass of callus tissue compared to other experimental options. In this variant, the growth index of callus tissue was the highest and amounted to 3.55. When the concentration of NPs increased to 50 μg/L, a decrease in the growth index was noted, which indicates their inhibitory effect on the proliferative activity of dedifferentiated cells. A comprehensive analysis of phenolic compounds was carried out in the resulting cell cultures. It was revealed that the accumulation of the total phenolics and flavonoids does not depend on the concentration of NPs in the MS medium.

Melatonin treatment induces DNA methylation to alleviate chilling induced-browning in cold stored peach fruit

Chilling injury (CI) often occurs in postharvest peach fruit during low-temperature storage, and exogenous melatonin (MT) treatment has been demonstrated to alleviate CI in cold-stored peach fruit. In this study, we further investigated the effect of MT treatment on DNA methylation in relation to the chilling-induced browning in cold stored peaches. The results revealed that MT treatment upregulated PpPAL expression while simultaneously suppressing the transcripts of PpPPO and PpPOD. This dual effect resulted in the increased accumulation of phenolics, effectively reducing the incidence of browning in peaches stored at 4 °C. In addition, MT treatment increased the activities of methylesterase and demethylase, affecting significant changes in the DNA methylation levels of the local genes PpPPO, PpPOD and PpPAL, which suggested that MT treatment could mediate DNA methylation of the browning-related genes such as PpPPO, PpPOD and PpPAL, and consequently increased the phenolic contents and alleviated browning symptoms in cold-stored peaches.

Combined application of alginate oligosaccharide and marine yeast Sporidiobolus pararoseus to control brown rot of peach fruit

Brown rot caused by Monilinia fructicola is the major fungal disease during postharvest storage of peach fruit. In this study, the effects of marine yeast Sporidiobolus pararoseus and alginate oligosaccharide (AOS) used alone or in combination to control brown rot in peach fruit were investigated. The results showed that AOS and S. pararoseus used alone could reduce the disease incidence and lesion diameter of brown rot, and their combination significantly increased the control effect than either treatment alone. Especially in the early stage of disease, the incidence of the untreated control fruit has reached 90%, while the incidences of AOS and S. pararoseus treatment were 36.7% and 30%, however, the combination treatment only showed 13.3% of incidence. The combination treatment of AOS and S. pararoseus can also reduce the weight loss and maintain fruit quality of peaches. Meanwhile, AOS could promote the colonization of S. pararoseus in peach fruit wounds and improve the survival of S. pararoseus under stresses. The combined treatment of S. pararoseus and AOS significantly increased the activities and gene expression of resistance-related enzymes such as catalase (CAT), phenylalanine ammonia-lyase (PAL), peroxidase (POD), polyphenol oxidase (PPO), β-1,3-glucanase (GNS), chitinase (CHI), promoted the accumulation of total phenols. These findings indicated that the increased biocontrol efficacy of AOS combined with S. pararoseus may be attributed to the promoting growth of S. pararoseus by AOS and the enhanced disease resistance of peaches. Overall, the combined application of AOS and S. pararoseus could be an effective method to control brown rot of peach fruit.

Integrated transcriptomics and metabolomics reveal specific phenolic and flavonoid accumulation in licorice (Glycyrrhiza uralensis Fisch.) induced by arbuscular mycorrhiza symbiosis under drought stress

Arbuscular mycorrhizal (AM) symbiosis can strengthen plant defense against abiotic stress, such as drought, through multiple mechanisms; however, the specialized chemical defenses induced by AM symbiosis are largely unknown. In a pot experiment, licorice (Glycyrrhiza uralensis Fisch.) inoculated with and without arbuscular mycorrhizal fungus Rhizophagus irregularis Schenck & Smith were grown under well-watered or water deficit conditions. Transcriptomic and metabolomic analyses were combined to investigate licorice root specialized metabolism induced by AM symbiosis under drought stress. Results showed that mycorrhizal plants had few dead leaves, less biomass reduction, and less differentially expressed genes and metabolite features in response to drought compared with nonmycorrhizal plants. Transcriptomic and metabolomic data revealed that mycorrhizal roots generally accumulated lignin regardless of the water regime; however, the expression of genes involved in lignin biosynthesis was significantly downregulated by drought stress in mycorrhizal plants. By contrast, AM inoculation significantly decreased specialized metabolites accumulation, including phenolics and flavonoids under well-watered conditions, whereas these decreases turned to be nonsignificant under drought stress. Moreover, these specific phenolics and flavonoids showed significant drought-induced accumulation pattern in mycorrhizal roots. These results highlight that accumulation of specific root phenolics and flavonoids may support the drought tolerance of mycorrhizal plants.

Melatonin Enhanced Drought Stress Tolerance and Productivity of Pelargonium graveolens L. (Herit) by Regulating Physiological and Biochemical Responses

As a type of abiotic stress, drought limits plant growth and productivity. The increased demand for the valuable essential oil extracted from geranium (Pelargonium graveolens L.) is mainly regulated by plant growth, which is adversely affected by drought. Melatonin (MT) has been used to enhance plant growth under various abiotic stresses, although its impact on overcoming drought stress in aromatic plants, including geranium, has not yet been investigated. In the current investigation, MT at 100 µM was applied at 100% (well-watered) or 50% (drought stress) field capacity to verify the role of MT in geranium under drought stress. Drought stress markedly reduced growth parameters, herb yield, and total chlorophyll content; however, MT alleviated these effects. The herb yield of the stressed plants was reduced by 59.91% compared to the unstressed plants, while this reduction was only 14.38% when MT was applied. In contrast, drought enhanced the essential oil percentage in geranium leaves. Despite the reduction in oil yield caused by drought, MT application mitigated this reduction and improved both oil yield and oil components. Moreover, the MT treatment enhanced the accumulation of total phenols, glutathione, and proline and improved the activity of ascorbate peroxidase, catalase, and glutathione reductase, resulting in the alleviation of drought-induced oxidative damage. Consequently, MT reduced both hydrogen peroxide and malondialdehyde accumulation by 71.11 and 48.30%, respectively, under drought, thereby maintaining the cellular structures’ integrity. Overall, this is the first report that reveals the ability of MT application to improve geranium oil yield and resistance to drought by enhancing the antioxidant defense system. The results enrich awareness regarding the potential benefits of the external application of MT and its roles that can help researchers to improve aromatic plants’ performance and productivity under drought stress.

Exogenous brassinolide treatment regulates phenolic accumulation in mung bean sprouts through the modulation of sugar and energy metabolism.

The effects of exogenous brassinolide (BR) treatment (3.0 μmol L-1 ) on phenolic biosynthesis in mung bean sprouts were investigated. This investigation included the analysis of sugar content, substrates within the phenylpropane pathway, energy substances, enzymatic activity within the phenylpropane pathway, sugar metabolism and energy metabolism. Results showed that BR treatment significantly increased the levels of total phenolics, p-hydroxybenzoic acid, p-coumaric acid, gallic acid, fumalic acid and caffeic acid. This enhancement was accomplished through the elevation of l-phenylalanine levels and the activation of enzymes associated with the phenylpropane pathway in mung bean sprouts, including phenylalanine ammonia-lyase, cinnamate 4-hydroxylase and 4-coumarate CoA ligase. Furthermore, BR treatment induced alterations in sugar metabolism in mung bean sprouts as evidenced by the increased levels of glucose, fructose, sucrose and phosphoenolpyruvate. Moreover, increased activity was observed for enzymes linked to sucrose metabolism and glycolysis in the BR-treated group. Concurrently, BR treatment bolstered the levels of adenosine triphosphate and energy charge in mung bean sprouts, which was attributed to the activation of H+ -adenosine triphosphatase, Ca2+ -adenosine triphosphatase and succinic dehydrogenase. These results suggest that BR treatment can accelerate the accumulation of phenolic compounds in mung bean sprouts. This effect is achieved not only through the activation of the phenylpropane pathway, but also through the modulation of sugar and energy metabolism. The modulation provides ample energy and a substrate for the biosynthesis of phenolics. © 2023 Society of Chemical Industry.

Influence of Storage Temperature on Levels of Bioactive Compounds in Shiitake Mushrooms (Lentinula edodes)

Shiitake mushroom (Lentinula edodes) hold high nutritional and medicinal value as they contain an abundance of health-promoting compounds. However, the effect of long-term postharvest storage on the variation in the levels of health-promoting compounds has not been extensively studied. In this study, we investigated the changes in the levels of phenolic compounds, antioxidants, eritadenine, and ergothioneine in shiitake mushrooms stored at three different temperatures (1, 3, and 5 °C) for 4 weeks. Compared to mushrooms stored at lower temperatures, those stored at 5 °C exhibited a higher level of total phenolics in their pileus after 2 weeks of storage; however, storage at 5 °C also increased the deterioration of the fruiting body of these mushrooms. In mushrooms stored at all temperatures, the eritadenine content in the pilei tended to increase up to 2 weeks of storage. In contrast, the ergothioneine content in the pileus decreased during storage, with a significantly lower level detected in mushrooms stored at 5 °C for 4 weeks. Together, these results suggest that the mechanisms underlying the accumulation of phenolics and eritadenine may be related to mushroom deterioration during storage. Our findings indicate that the levels of health-promoting compounds in shiitake mushrooms are influenced by storage temperature, suggesting the potential to control adjustments of specific bioactive compounds by regulating storage conditions.

Bordeaux mixture accelerates ripening, delays senescence, and promotes metabolite accumulation in jujube fruit

Abstract The old, but eco-friendly pesticide, Bordeaux mixture (Bm), is widely used in agriculture. Here, the effects of Bm on preharvest fruit ripening, and postharvest senescence of fruit and the accumulation of antioxidants were studied in Ziziphus jujuba. A 200× dilution of Bm enhanced preharvest ripening and retarded jujube fruit postharvest senescence. Treatment with Bm increased the reddening index and promoted the accumulation of total phenolics (TP) and the total antioxidant capacity (TAC) in preharvest fruit. However, this Bm-accelerated ripening could be partly reversed using dimethylthiourea (DMTU), a specific scavenger of reactive oxygen species. Compared with preharvest fruit, Bm treatment decreased weight loss and decay and increased firmness in postharvest fruit. Similarly, Bm-delayed senescence was partly reversed using dimethylthiourea. Moreover, the decrease in TP and TAC during storage was partly impeded by Bm. A higher H2O2 content was detected in preharvest fruit than in postharvest fruit. Moreover, this Bm-induced H2O2 accumulation was significantly mitigated using dimethylthiourea. Interestingly, both preharvest and postharvest spraying with Bm significantly enhance copper and calcium accumulation in fruit. Thus, Bm can be widely used before or after harvest to improve fruit quality.