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BACKGROUND: This study evaluated the effects of nitric oxide (NO) treatment on ascorbic acid (AsA) metabolism and mung bean sprout quality. It examined changes in the AsA content, enzyme activity associated with AsA metabolism, antioxidant capacity, cell membrane composition, and cellular structure to clarify the effects of NO on mung bean sprouts. RESULTS: Nitric oxide treatment preserved mung bean sprout quality by enhancing significantly the activity of enzymes involved in the l‐galactose pathway (including guanosine diphosphate (GDP)glutathione (‐d‐mannose pyrophosphorylase, GDP‐mannose‐3′,5′‐epimerase, GDP‐l‐galactose phosphorylase, l‐galactose‐1‐phosphate phosphatase, l‐galactose dehydrogenase, and l‐galactose‐1,4‐lactone dehydrogenase) and the AsA‐glutathione (GSH)(Beijing Solarbio Science and Technology Co.,Ltd., Beijing, China) cycle (including ascorbate peroxidase, ascorbic acid oxidase, glutathione reductase, dehydroascorbate reductase, and monodehydroascorbate reductase) during the germination and storage stage. Increased enzyme activity led to an increase in AsA content and enhanced antioxidant capacity, and reduced the membrane lipid damage in mung bean sprouts. This was demonstrated by higher levels of DPPH radical scavenging capacity, unsaturated fatty acids and phospholipids, along with lower levels of hydrogen peroxide, superoxide anions, and malondiadehyde, in NO‐treated mung bean sprouts. Scanning electron microscopy also revealed that NO treatment maintained the integrity of the cellular structure of the mung bean sprouts. CONCLUSION: Nitric oxide accelerates AsA metabolism effectively by regulating the biosynthesis and regeneration of AsA in mung bean sprouts. These changes increased AsA levels, alleviated membrane lipid damage, delayed senescence, and maintained the quality of mung bean sprouts during storage. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Understanding the early interactions between plants and endophytes will contribute to a more systematic approach to enhancing endophyte-mediated effects on plant growth and environmental stress resistance. This study examined very early growth and ascorbate metabolism after seed treatment of Brassica napus with three different endophytes. The three endophytes used were Bacillus amyloliquefaciens pb1(Bapb1), Micrococcus luteus (Ml) and Pseudomonas fluorescens SLB4 (SLB4). Seeds of Brassica napus cv. trophy were surface sterilized and plated on 1/2 MS Basal salts (pH 5.7 -5.8) + 0.8% agarose. Under sterile conditions, endophyte suspensions or sterile distilled water (controls) were applied to plated seeds. After two days, all plates were scanned to produce digital images for subsequent growth analysis. Then, seedlings were gently removed from the plates and placed in sterile microfuge tubes. For biochemical analyses, extracts were prepared from samples and assayed spectrophotometrically. We detected slight changes in seedling root tip and/or primary root growth with Bapb1 and Ml. Seedlings treated with SLB4 exhibited significantly increased primary root and root tip length after two days of growth. Ascorbate oxidation, however, was the primary significant change common to all endophyte-treated seedlings. In relation to ascorbate oxidation, soluble ascorbate oxidase (AO) was slightly reduced in Bapb1 and Ml-treated seedlings, whereas ionically-bound AO was reduced in Bapb1 and SLB4-treated seedlings. Total AO activity was significantly reduced in Bapb1-treated seedlings. There were no differences in cytosolic APX activity or glutathione levels between endophyte-treated seedlings and controls. Like pathogens, endophytes can trigger an oxidative burst in the plant. A level of ascorbate oxidation seems required to propagate ROS as signaling molecules as part of the plant immune response. The slight to moderate reductions in plant AO activity that we found mimic the inhibitory effects of pathogens on AO activity, but there was still a level of AO activity that may have been sufficient for the apoplastic ascorbate oxidation required for subsequent ROS signaling. Other studies have suggested that endophytes may elicit a more moderate plant immune response relative to pathogens to facilitate colonization. The AO, APX, and glutathione results would be consistent with a moderate plant immune response to endophytes. [ABSTRACT FROM AUTHOR]

In order to understand the physiological mechanism of drought stress affecting premature leaf senescence of the pod subtending leaf during flowering and pod period, a pot experiment was conducted in Hefei, Anhui Province from 2021 to 2022. The effects of drought stress on the endogenous protective enzyme system and ascorbate glutathione cycle were studied based on the antioxidant metabolism system at soil water content (SWC) (75 ± 5)%, (60 ± 5)% and (45 ± 5)% on two soybean varieties (Wandou 37, drought weak sensitive variety; Wandou 38, drought sensitive variety). The results revealed that drought accelerated the senescence of pod subtending leaf, with SPAD decreasing by 8.0%-24.2% for Wandou 37 and by 12.4%-32.9% for Wandou 38. The activities of superoxide dismutase (SOD) and peroxidase (POD) and the content of ascorbic acid (ASA) were significantly increased in the pod subtending leaf, however the activities of ascorbate oxidase (APX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) were inhibited by drought stress. A large amount of H2O2 and O2- could not be completely removed, resulting in the increase of H2O2 and MDA content, and the increase of O2- production rate, which resulted in acceleration of leaf senescence. SWC (45 ± 5)% treatment was significantly higher than SWC (60 ± 5)% treatment, and the results were consistent between the two varieties. Compared with Wandou 38, Wandou 37 had higher GR and PAX activities under drought stress, increased ASA content, reduced H2O2 and O2- accumulation, and reduced the degree of membrane lipid peroxidation. Therefore it improved the resistance to drought adversity. [ABSTRACT FROM AUTHOR]

Lignin is a phenolic polymer that is a major source of biomass. Oxidative enzymes, such as laccase and peroxidase, are required for lignin polymerisation. Laccase is a member of the multicopper oxidase family and has a high amino acid sequence similarity with ascorbate oxidase. However, the process of functional differentiation between the two enzymes remains poorly understood. In this study, the common ancestry sequence of laccase and ascorbate oxidase (AncMCO) was predicted via phylogenetic reconstruction, and its in vivo effect on lignin biosynthesis in Arabidopsis thaliana was assessed. The estimated AncMCO sequence conserved key residues that coordinate with copper ions, implying that the electron transfer system is likely to be conserved in AncMCO. However, multiple insertions/deletions corresponding to protein surface structures have been found between laccase, ascorbate oxidase, and AncMCO. The overexpression of canonical laccase (AtLAC4) and ascorbate oxidase (AtAAO1) in A. thaliana resulted in notable increases of syringyl/guaiacyl lignin unit ratio in stems, whereas, in contrast, the overexpression of AncMCO did not show any detectable change in lignin deposition. Transcriptomic analysis revealed that the AtAAO1-overexpressing line exhibited significant changes in the expression of a wide range of cell wall biosynthesis genes. These results highlight the importance of the molecular evolution of multicopper oxidase, which drives lignin biosynthesis during plant evolution. [ABSTRACT FROM AUTHOR]

Mango (Mangifera indica), a nutritionally rich tropical fruit, is significantly impacted by UV-B radiation, which induces oxidative stress and disrupts physiological processes. This study aimed to investigate mango pulp's molecular and biochemical responses to UV-B stress (96 kJ/mol) from the unripe to mature stages over three consecutive years, with samples collected at 10-day intervals. UV-B stress affected both non-enzymatic parameters, such as maturity index, reactive oxygen species (ROS) levels, membrane permeability, and key enzymatic components of the ascorbate-glutathione (AsA-GSH) cycle. These enzymes included glutathione reductase (GR), gamma-glutamyl transferase (GGT), glutathione S-transferases (GST), glutathione peroxidase (GPX), glucose-6-phosphate dehydrogenase (G6PDH), galactono-1,4-lactone dehydrogenase (GalLDH), ascorbate peroxidase (APX), ascorbate oxidase (AAO), and monodehydroascorbate reductase (MDHAR). Transcriptomic analysis revealed 18 differentially expressed genes (DEGs) related to the AsA-GSH cycle, including MiGR, MiGGT1, MiGGT2, MiGPX1, MiGPX2, MiGST1, MiGST2, MiGST3, MiG6PDH1, MiG6PDH2, MiGalLDH, MiAPX1, MiAPX2, MiAAO1, MiAAO2, MiAAO3, MiAAO4, and MiMDHAR, validated through qRT-PCR. The findings suggest that UV-B stress activates a complex regulatory network in mango pulp to optimize ROS detoxification and conserve antioxidants, offering insights for enhancing the resilience of tropical fruit trees to environmental stressors. [ABSTRACT FROM AUTHOR]

As a great economic Solanum with ornamental value and good adaptability, Solanum aculeatissimum is considered an excellent candidate for the phytoremediation of Cadmium-contaminated soils. However, there are no studies on the involvement of S. aculeatissimum in the response and tolerance mechanisms of cadmium (Cd) stress. In the present study, S. aculeatissimum was used for the first time for physiological and transcriptomic systematic analysis under different concentrations of Cd stress. The results showed that S. aculeatissimum was indeed well tolerant to Cd and showed Cd enrichment capabilities. Under the Cd stress treatment of 50 mg/kg (Cd6), S. aculeatissimum could still grow normally. At the 90th day of Cd stress, the amount of Cd content in different parts of the plant at the same concentration was in the order of root > stem > leaf. With the extension of the stress time up to 163 d, the trend of Cd content in each part was not consistent, and the results in the root (77.74 mg/kg), stem (30.01 mg/kg), leaf (29.44 mg/kg), immature fruit (18.36 mg/kg), and mature fruit (21.13 mg/kg) of Cd peaked at Cd4, Cd5, Cd1, Cd4, and Cd4, respectively. The enrichment and transport coefficients of all treatments were greater than 1. The treatment groups with the largest and smallest enrichment coefficients were Cd4 and CK, respectively. The treatment groups with the largest and smallest transport coefficients were CK and Cd4, respectively. Malondialdehyde (MDA), peroxidase (POD), and catalase (CAT) in the antioxidant system after Cd stress treatment were significantly increased compared to the untreated group. Under cadmium stress, by using real-time quantitative PCR, four genes (SaHMA20, SaL-AO, SaPrxs4, and SaPCs) were screened for possible correlations to Cd tolerance and absorption enrichment in S. aculeatissimum. The key DEGs are mainly responsible for the metabolic pathways of heavy metal ATPases, plastocyanin protein phytocyanins (PCs), peroxidases (Prxs), and ascorbate oxidase (AAO); these differential genes are believed to play an important role in Cd tolerance and absorption enrichment in S. aculeatissimum. [ABSTRACT FROM AUTHOR]

Background: Reduction of the production of amyloid-β (Aβ) species has been intensively investigated as potential therapeutic approaches for Alzheimer's disease (AD). However, the degradation of Aβ species, another potential beneficial approach, has been far less explored. Objective: To investigate the potential of multi-copper oxidases (MCOs) in degrading Aβ peptides and their potential benefits for AD treatment. Methods: We investigated the degradation efficiency of MCOs by using electrophoresis and validated the ceruloplasmin (CP)-Aβ interaction using total internal reflection fluorescence microscopy, fluorescence photometer, and fluorescence polarization measurement. We also investigated the therapeutic effect of ascorbate oxidase (AO) by using induced pluripotent stem (iPS) neuron cells and electrophysiological analysis with brain slices. Results: We discovered that CP, an important MCO in human blood, could degrade Aβ peptides. We also found that other MCOs could induce Aβ degradation as well. Remarkably, we revealed that AO had the strongest degrading effect among the tested MCOs. Using iPS neuron cells, we observed that AO could rescue neuron toxicity which induced by Aβ oligomers. In addition, our electrophysiological analysis with brain slices suggested that AO could prevent an Aβ-induced deficit in synaptic transmission in the hippocampus. Conclusions: To the best of our knowledge, our report is the first to demonstrate that MCOs have a degrading function for peptides/proteins. Further investigations are warranted to explore the possible benefits of MCOs for future AD treatment. [ABSTRACT FROM AUTHOR]

Soil mercury (Hg) contamination is a serious threat to local ecology and public health. Exogenous selenium (Se) supplementation can effectively reduce the toxicity of Hg. However, the mechanisms affecting the changes in soil Hg speciation, soil properties and the microbial Hg-resistant system during the Se–Hg interaction after exogenous Se supplementation are not clear. Therefore, in this study, soil culture experiments were conducted to analyze the effects of different Se additions on the transformation of Hg speciation, soil properties and Hg-resistant microorganisms and resistant genes (mer operon). The results indicated that Se supplementation facilitated the transformation of soil Hg from bioavailable (exchangeable and carbonate-bound) to stable forms (organic material-bound and residual), significantly reducing Hg bioavailability. Se supplementation notably decreased the electrical conductivity of Hg-contaminated soil, but had no significant effect on the soil pH, organic matter content, cation exchange capacity or alkaline phosphatase and catalase activities. The maximum activity levels of soil sucrase and urease were observed when 1 mg kg−1 Se was added. Se significantly inhibited soil peroxidase and ascorbate oxidase activities, thereby alleviating the oxidative stress in the soil system caused by Hg. Additionally, Se significantly activated the Hg-resistant system in soil microorganisms by either decreasing or increasing the regulatory genes merD and merR, and it significantly upregulated the cytoplasmic protein gene merP and the membrane protein genes merC, merF and merT. This further increased the abundance of the organomercury lyase gene merB and the mercuric reductase gene merA, promoting the conversion of Hg species to Hg⁰. Furthermore, the abundance of mer operon-containing microorganisms, such as Thiobacillus ferrooxidants, Pseudomonas, Streptomyces and Cryptococcus, significantly increased with Se addition, explaining the role of soil microorganisms in mitigating soil Hg stress via Se supplementation. [ABSTRACT FROM AUTHOR]

Ascorbate oxidase (AAO) plays an important role in maintaining cellular redox homeostasis, thereby influencing plant growth, development, and responses to both biotic and abiotic stresses. However, there has been no systematic characterization of AAO genes in Citrus, especially their roles in response to cold stress. In the present study, nine AAO genes were identified in C. sinensis through bioinformatics analyses, exhibiting uneven distribution across four chromosomes. All CsAAOs possessed three conserved domains and were predicted to localize in the apoplast. The CsAAO gene family displayed varied intron–exon patterns. Phylogenetic analysis categorized the CsAAO family into three main clades (Clade A–C), suggesting distinct biological functions. Collinearity and Ka/Ks analysis revealed three duplicate gene pairs within the CsAAO gene family, with all duplicated CsAAOs primarily evolving under purifying selection. Analysis of cis-acting elements showed the presence of multiple hormone response elements and stress response elements within the CsAAO promoters. The computational analysis of microRNA target transcripts suggested that CsAAO9 may be a target of csi-miR156. RNA-Seq data demonstrated high expression levels of CsAAOs in roots and young fruits, while qRT-PCR analysis showed significant upregulation of six CsAAOs in response to cold treatment. Furthermore, the activities of CsAAOs exhibited a pattern of initial decrease followed by an increase after exposure to low temperatures. These findings offer important insights into the role of CsAAOs in response to cold stress. Furthermore, AAOs could be target genes for breeding crops with better cold resistance. [ABSTRACT FROM AUTHOR]

Mango (Mangifera indica) is a highly valuable horticultural crop known for its quality and productivity. This study investigates the dynamic changes in physicochemical properties and glutathione and ascorbic acid metabolic pathways in mango pulp across various growth and development stages over two consecutive years (2021–2022 and 2022–2023) by transcriptomic analysis. Overall, the results demonstrate that during different ripening periods, the pulp shows increased levels of total soluble solids, relative conductivity, glutathione, and enzymes, while titratable acidity, malondialdehyde, reactive oxygen species, and ascorbic acid contents decreased. Moreover, transcriptomic analysis identified key differentially expressed genes from the glutathione and ascorbic acid metabolic pathways and validated them with qRT-PCR. In different comparisons, a total of 1776, 2513, and 828 DEGs were identified in 30 vs. 60, 30 vs. 90, and 60 vs. 90 days after flowering, respectively. Among them, seven DEGs were primarily enriched in relevant pathways, which included ascorbate peroxidase, ascorbate oxidase, glutathione peroxidase, gamma-glutamyl transferase, glutathione transferases, and glucose-6-phosphate dehydrogenase. The upregulation of these genes indicates that glutathione and AsA respond well to scavenging reactive oxygen species and maintain normal functioning in plants. This research sheds light on the molecular mechanisms of glutathione and ascorbic acid dynamic changes in mango pulp, providing valuable insights into the regulation of antioxidant and metabolic pathways during fruit growth and development. [ABSTRACT FROM AUTHOR]

Bionomics of an insect and metabolic flux of the host plant are important tools to decipher the status of plant resistance against insect species. This study illuminates vital information on aphid‐induced levels of phytochemicals in the siliquae of Brassica juncea cultivars and their effect on host selection and population growth parameters of Lipaphis erysimi. The current study unveiled that the siliquae preference, intrinsic rate of increase (r), finite rate of increase (λ), gross reproductive rate (GRR) and net reproductive rate (R0) were significantly lower on Pusa Mustard 27, DRMR 150‐35, RLC 3, NRCHB 101, Pusa Mustard 26 and Pusa Mustard 25. However, the mean generation time (T) and doubling time (DT) of L. erysimi were significantly longer (p < 0.001) in these genotypes. These cultivars were also found with elevated levels of aphid‐induced phytochemicals and their associated enzymes, except in a few cases. Total antioxidants, ferric ion reducing antioxidant power, chlorophyll A, total chlorophyll, ascorbate oxidase (AO), catalase, phenylalanine ammonia lyase (PAL) and myrosinase were found to contribute 49.18–85.30% variation for siliquae preference and bionomics of L. erysimi on the test B. juncea cultivars. The study revealed that phenols, antioxidants, chlorophyll A, chlorophyll B, total carotenoids, AO, ascorbate peroxidase, PAL, tyrosine ammonia lyase and myrosinase had significant and negative direct consequences on the siliquae preference and bionomics, thus can be exploited as biochemical markers to identify sources of resistance against L. erysimi. Furthermore, DRMR 150‐35, NRCHB 101, RLC 3, Pusa mustard 26, RH 749 and Pusa Mustard 27 were found with greater aphid‐induced defence phytochemicals and detrimental effects on the host selection and bionomics of L. erysimi, thus can be deployed in Brassica improvement program. [ABSTRACT FROM AUTHOR]

Improving the drought resistance of rice is of great significance for expanding the planting area and improving the stable yield of rice. In our previous work, we found that ROLLED AND ERECT LEAF1 (REL1) protein promoted enhanced tolerance to drought stress by eliminating reactive oxygen species (ROS) levels and triggering the abscisic acid (ABA) response. However, the mechanism through which REL1 regulates drought tolerance by removing ROS is unclear. In this study, we identified REL1 interacting protein 5 (RIP5) and found that it directly combines with REL1 in the chloroplast. We found that RIP5 was strongly expressed in ZH11 under drought-stress conditions, and that the rip5-ko mutants significantly improved the tolerance of rice plants to drought, whereas overexpression of RIP5 resulted in greater susceptibility to drought. Further investigation suggested that RIP5 negatively regulated drought tolerance in rice by decreasing the content of ascorbic acid (AsA), thereby reducing ROS clearance. RNA sequencing showed that the knockout of RIP5 caused differential gene expression that is chiefly associated with ascorbate and aldarate metabolism. Furthermore, multiple experimental results suggest that REL1 is involved in regulating drought tolerance by inhibiting RIP5. Collectively, our findings reveal the importance of the inhibition of RIP5 by REL1 in affecting the rice's response to drought stress. This work not only explains the drought tolerance mechanism of rice, but will also help to improve the drought tolerance of rice. [ABSTRACT FROM AUTHOR]

6-BA, a small molecule compound of cytokinins, has been proven to delay leaf senescence in different species, including Chinese flowering cabbage; however, its specific mechanism remains relatively unknown. In this study, the application of external 6-BA delayed leaf senescence in Chinese flowering cabbage, showing that 6-BA effectively prevented the decrease in the maximum quantum yield (Fv/Fm) and overall chlorophyll content and suppressed the expression of the senescence-associated gene BrSAG12 over a 7-day period of storage. Moreover, treatment with 6-BA decreased the respiratory rate, NAD(H) content, the activities of hexose phosphate isomerase (PHI), succinate dehydrogenase (SDH), cytochrome c oxidase (CCO), and ascorbic acid oxidase (AAO) using enzyme-linked immunosorbent assay, and the transcriptional abundance of related genes by real-time quantitative polymerase chain reaction. Furthermore, 6-BA also increased the activity and expression levels of glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphate gluconate dehydrogenase (6-PGDH). The group treated with 6-BA retained elevated levels of NADP (H), ATP, total ATPase, and nicotinamide adenine dinucleotide kinase (NADK) activity, as well as the expression of respiratory enzymes. Molecular docking indicated that 6-BA hinders the glycolysis pathway (EMP), tricarboxylic acid cycle (TCA), and cytochrome pathway (CCP), and sustains elevated levels of the pentose phosphate pathway (PPP) through interactions with the PHI, SDH, 6-PGDH, G6PDH, CCO, and AAO proteins, consequently delaying postharvest leaf senescence in Chinese flowering cabbage. [ABSTRACT FROM AUTHOR]

This Special Issue was assembled to mark the 25th anniversary of the proposal of the d -mannose/ l -galactose (Smirnoff–Wheeler) ascorbate biosynthesis pathway in plants (Wheeler et al. , 1998). The issue aims to assess the current state of knowledge and to identify outstanding questions about ascorbate metabolism and functions in plants. [ABSTRACT FROM AUTHOR]

Ascorbic acid (AsA) plays an indispensable role in plants, serving as both an antioxidant and a master regulator of the cellular redox balance. Ascorbate oxidase (AO) is a blue copper oxidase that is responsible for the oxidation of AsA with the concomitant production of water. For many decades, AO was erroneously postulated as an enzyme without any obvious advantage, as it decreases the AsA pool size and thus is expected to weaken plant stress resistance. It was only a decade ago that this perspective shifted towards the fundamental role of AO in orchestrating both AsA and oxygen levels by influencing the overall redox balance in the extracellular matrix. Consistent with its localization in the apoplast, AO is involved in cell expansion, division, resource allocation, and overall plant yield. An increasing number of transgenic studies has demonstrated that AO can also facilitate communication between the surrounding environment and the cell, as its gene expression is highly responsive to factors such as hormonal signaling, oxidative stress, and mechanical injury. This review aims to describe the multiple functions of AO in plant growth, development, and stress resilience, and explore any additional roles the enzyme might have in fruits during the course of ripening. [ABSTRACT FROM AUTHOR]

Melatonin (MT) is an important plant growth regulator that significantly regulates the growth and development of plants. Previous studies confirmed the effectiveness of MT in improving plant stress tolerance. In this study, annual M9-T337 seedlings were selected as subjects, and five treatments were applied: control (CK), in which only half the concentration of Hoagland was applied; Saline-alkaline stress treatment (SA, 100 mmol·L−1 saline-alkaline solution); melatonin treatment (MT, CK + 200 μmol L−1 exogenous MT); Saline-alkaline + melatonin treatment (MS, SA + 200 μmol L−1 exogenous MT); and saline-alkaline stress + melatonin + inhibitor treatment (HS, additional 100 μmol L−1 p-CPA treatment to MS). The results showed that saline-alkaline stress negatively affected the growth of M9-T337 seedlings by reducing photosynthetic capacity, increasing Na+, promoting reactive oxygen species such as H2O2, and changing the osmotic content and antioxidant system. However, the application of exogenous MT effectively alleviated saline-alkaline damage and significantly promoted the growth of M9-T337 seedlings. It significantly increased plant height, diameter, root length, root surface area, volume and activity. Furthermore, MT alleviated osmotic stress by accumulating proline, soluble sugars, soluble proteins and starch. MT improved photosynthetic capacity by delaying chlorophyll degradation and regulating gas exchange parameters as well as fluorescence parameters in leaves. Additionally, MT reduced the Na+/K+ ratio to reduce ion toxicity by upregulating the expression of Na+ transporter genes (MhCAX5, MhCHX15, MhSOS1, and MhALT1) and downregulating the expression of K+ transporter genes (MhSKOR and MhNHX4). In addition, MT can increase antioxidant enzyme activity (superoxide dismutase (SOD), peroxidase(POD), catalase (CAT), ascorbic acid oxidase (AAO), ascorbate peroxidase (APX) and monodehydroascorbate reductase (MDHAR)) in the ASA-GSH cycle and increase ascorbic acid (AsA), reduced glutathione (GSH) and oxidized glutathione (GSSG) levels to counteract the accumulation of reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) and Superoxide anion free radicals (O2−), reducing oxidative damage. Exogenous MT promotes M9-T337 seedlings growth under saline-alkaline stress by responding synergistically with auxin (IAA), gibberellin (GA3) and zeatin (ZT) to saline-alkaline stress. Our results confirm that MT has the potential to alleviate Saline-alkaline stress by promoting root growth, increasing biomass accumulation and photosynthetic capacity, strengthening the antioxidant defense system, maintaining ionic balance, the ascorbate–glutathione cycle and the Osmoregulation facilitates and regulates endogenous hormone levels in M9-T337 seedlings. [ABSTRACT FROM AUTHOR]

This paper reports a study aimed at determining the biochemical quality indicators of grapes during long-term storage. The object of research was nine table varieties of ripened grapes. These include white varieties – Tabrizi, Karaburnu, White Shasla, Agadai; pink varieties – Nimrang, Marandi Shamakhi, Taifi pink; red varieties – Kyzyl raisins and Hamburg Muscat. The grapes were stored in refrigerators for 5–6 months, at a temperature of 0–1 °C and air humidity of 87–95 %. The grapes were studied before planting and 30–40 days before the end of storage. Long-term refrigerated storage of grapes using weekly fumigation with sulfur dioxide is accompanied by a decrease in the activity of oxyreductases and a gradual increase in the activity of pectinesterase. This causes changes in the quantity and proportions of nutrients and other chemical components that determine the nutritional and biological value of the final product. It was revealed that during the sale of ripened grapes stored using weekly fumigation with sulfur dioxide, the activity of the studied oxyreductases is slightly restored in pink varieties – Nimrang, Taifi pink, and in white varieties – in Karaburnu and Tabrizi. In the Marandi Shamakhi variety, the activity of enzymes does not change, therefore, for a long time in these grape varieties, especially in the Marandi Shamakhi variety, darkening and softening of the berries are not observed during their sale. Among the studied table grape varieties, Tabrizi, Karaburnu, Nimrang, and Marandi Shamakhi, with long-term refrigerated storage using weekly fumigation with sulfur dioxide, have the longest shelf life; under a controlled gas environment, the results reported here could prove useful in practice. [ABSTRACT FROM AUTHOR]

Arsenic (As) is a toxic element for plants, animals and humans. The mitigation of As stress has been achieved via selenium (Se) and silica (Si) supplementations. However, the effects of combined application of Se and Si against As stress are not known. The present study was conducted to evaluate the effect of Se (0.5 and 1 mg L−1) and Si (10 and 30 mg L−1) on Oryza sativa L. (rice) subjected to during As (4 mg L−1) stress. The rice plants showed reduction in As accumulation in co-treatment of As + Se, As + Si and As + Se + Si in comparison to As alone treated plants (7 d). The maximum reduction of As accumulation in root and shoot was 57% and 64%, respectively in As + Se + Si treatment. The increase in enzymatic antioxidant system (superoxide dismutase, ascorbate peroxidase, glutathione peroxidase, glutathione reductase and glutathione-s-transferase) along with decrease in oxidative stress markers (lipid peroxidation, dehydroascorbate reductase, ascorbate oxidase and hydrogen peroxide) in As + Se + Si treatment as compared to As treatment signified elevated tolerance of rice plants to As stress. Gene expressions of enzymes involved in antioxidant defence and thiol metabolism were found to be significantly positively correlated with their respective biochemical activities. In conclusion an optimum combination of Se and Si can be used to effectively mitigate As toxicity in plants. [ABSTRACT FROM AUTHOR]

Continuous spring cropping of Qingke (Hordeum viilgare L. var. nudum Hook. f.) results in a reduction in grain yield in the Xizang autonomous region. However, knowledge on the influence of continuous cropping on grain yield caused by reactive oxygen species (ROS)-induced stress remains scarce. A systematic comparison of the antioxidant defensive profile at seedling, tillering, jointing, flowering, and filling stages (T1 to T5) of Qingke was conducted based on a field experiment including 23-year continuous cropping (23y-CC) and control (the first year planted) treatments. The results reveal that the grain yield and superoxide anion (SOA) level under 23y-CC were significantly decreased (by 38.67% and 36.47%), when compared to the control. The hydrogen peroxide content under 23y-CC was 8.69% higher on average than under the control in the early growth stages. The higher ROS level under 23y-CC resulted in membrane lipid peroxidation (LPO) and accumulation of malondialdehyde (MDA) at later stages, with an average increment of 29.67% and 3.77 times higher than that in control plants. Qingke plants accumulated more hydrogen peroxide at early developmental stages due to the partial conversion of SOA by glutathione (GSH) and superoxide dismutase (SOD) and other production pathways, such as the glucose oxidase (GOD) and polyamine oxidase (PAO) pathways. The reduced regeneration ability due to the high oxidized glutathione (GSSG) to GSH ratio resulted in GSH deficiency while the reduction in L-galactono-1,4-lactone dehydrogenase (GalLDH) activity in the AsA biosynthesis pathway, higher enzymatic activities (including ascorbate peroxidase, APX; and ascorbate oxidase, AAO), and lower activities of monodehydroascorbate reductase (MDHAR) all led to a lower AsA content under continuous cropping. The lower antioxidant capacity due to lower contents of antioxidants such as flavonoids and tannins, detected through both physiological measurement and metabolomics analysis, further deteriorated the growth of Qingke through ROS stress under continuous cropping. Our results provide new insights into the manner in which ROS stress regulates grain yield in the context of continuous Qingke cropping. [ABSTRACT FROM AUTHOR]

Enzymatic activity of soils is the most important diagnostic indicator of the ecological state of soils affected by various types of anthropogenic impact. The aim of the study was to evaluate the enzymatic activity of ordinary chernozem (Haplic Chernozem) contaminated with Ag, Bi, Te, and Tl. Ten enzymes (catalase, dehydrogenase, peroxidase, polyphenol oxidase, ascorbate oxidase, ferrireductase, protease, phosphatase, invertase, and urease) were analyzed. According to the degree of inhibition of enzymes, heavy metals formed the following sequence: Tl > Ag > Bi > Te. With an increase in the concentration of heavy metals, the toxic effect on the activity of enzymes increased. The oxidoreductases showed greater sensitivity to Ag, Bi, Te, and Tl contamination than hydrolases. Among oxidoreductases, the highest sensitivity was found for ferrireductase, and the lowest one for ascorbate oxidase. According to the activity of enzymes of the hydrolase class, invertase was the most sensitive, and urease was the least sensitive. When contaminated with Ag, Bi, and Te, invertase had the highest informative value, and when contaminated with Tl, urease and polyphenol oxidase were the most informative. Among the enzymes of the oxidoreductase class, the highest information value was found for peroxidase, and the lowest one for ascorbate oxidase. Among the enzymes of the hydrolase class, invertase was the most sensitive, and phosphatase was the least sensitive. The results of the study can be used to assess the ecological state of soils contaminated with Ag, Bi, Te and Tl. [ABSTRACT FROM AUTHOR]

Shoot fly is a devastating pest and causes a serious threat to sorghum. In the present investigation, oxidative enzymes, guaiacol peroxidase (GPX), tyrosine ammonia lyase (TAL) and biochemical metabolites were studied for shoot fly resistance in six sorghum genotypes at 15 and 21 days after emergence (DAE). The plant material had been categorized into resistant genotypes (IS18551, ICSV705, and ICSV700), moderately resistant genotype (PSC-4) and susceptible genotypes (SWARNA and SL-44) on the basis of observed shoot fly resistance. All the enzymes showed an upregulated trend in their activity with shoot fly infestation. The oxidative enzymes diamine oxidase (DAO) and polyamine oxidase (PAO) upregulated to 1.6 fold and 2.0 fold in susceptible genotypes. Ascorbate oxidase (AOX) activity was also higher in resistant genotypes at 21 DAE. The increased production of H2O2 by PAO and DAO led to the activation of the H2O2-metabolising enzyme GPX by 3.5 fold and 2.0 fold in leaf and stem tissue of susceptible genotypes as compared to resistant genotypes at both sampling stages. The response of the phenylpropanoid pathway enzyme TAL was upregulated more in leaf of the resistant genotype ICSV705 (2.12 fold) at 21 DAE leading to production of phenolic constituents viz. flavanols and condensed tannin. These key enzymes along with oxidative enzymes enable the resistant genotypes to tolerate the biotic stress as evident from the lower content of thiobarbituric acid reactive substance (TBRAS) in resistant genotypes compared to the susceptible ones. [ABSTRACT FROM AUTHOR]

Kiwifruit exhibits a climacteric ripening pattern and has as an extremely perishable nature. Considering that high perishability leads to a loss in antioxidants and overall nutritional quality. This study aimed to examine the efficacy of enhanced freshness formulation (EFF), a hexanal-based formulation containing antioxidants such as geraniol, α-tocopherol and ascorbic acid, on maintaining the bioactive compounds of gold kiwifruit (cv. 'Y368') harvested at two maturity stages. Kiwifruits were treated with three treatments, namely, control (untreated fruit), 0.01 and 0.02% (v/v) EFF. Fruits were treated with 8 weeks of cold storage at 0°C and 90% relative humidity, then transferred to 20°C for 8 days. Three bioactive compounds (ascorbic acid, total phenolics and flavonoids), antioxidant capacities using DPPH and FRAP assays, polyphenol oxidase, ascorbate oxidase, phenylalanine and tyrosine ammonia lyase enzyme activities were evaluated. The results showed that EFF significantly (p < 0.05) influenced bioactive compounds, antioxidant capacities and the activity of enzymes involved in the synthesis and oxidation of bioactive compounds. The maturity stage significantly influenced the content of bioactive compounds. Later harvested kiwifruit had greater content of bioactive compounds, compared to earlier harvested kiwifruit. The total phenolic content was 0.77, 1.09 and 1.22 mg GAE g-1 FW for control, 0.01 and 0.02% EFF, respectively. The FRAP antioxidant concentration was 0.76, 0.91 and 0.96 μmol Fe (II) g-1 FW for control, 0.01 and 0.02% EFF. The findings illustrate the capacity of EFF to optimize bioactive compounds and storability of kiwifruit during postharvest storage. [ABSTRACT FROM AUTHOR]

The level of cadmium (Cd) accumulation in orchard soils is increasing, and excess Cd will cause serious damage to plants. Melatonin is a potent natural antioxidant and has a potential role in alleviating Cd stress. This study aimed to investigate the effects of exogenous melatonin on a root endophyte bacteria community and metabolite composition under Cd stress. The results showed that melatonin significantly scavenged the reactive oxygen species and restored the photosynthetic system (manifested by the improved photosynthetic parameters, total chlorophyll content and the chlorophyll fluorescence parameters (Fv / Fm)), increased the activity of antioxidant enzymes (the activities of catalase, superoxide dismutase, peroxidase and ascorbate oxidase) and reduced the concentration of Cd in the roots and leaves of apple plants. High-throughput sequencing showed that melatonin increased the endophytic bacterial community richness significantly and changed the community structure under Cd stress. The abundance of some potentially beneficial endophytic bacteria (Ohtaekwangia , Streptomyces , Tabrizicola and Azovibrio) increased significantly, indicating that the plants may absorb potentially beneficial microorganisms to resist Cd stress. The metabolomics results showed that melatonin significantly changed the composition of root metabolites, and the relative abundance of some metabolites decreased, suggesting that melatonin may resist Cd stress by depleting root metabolites. In addition, co-occurrence network analysis indicated that some potentially beneficial endophytes may be influenced by specific metabolites. These results provide a theoretical basis for studying the effects of melatonin on the endophytic bacterial community and metabolic composition in apple plants. [ABSTRACT FROM AUTHOR]

Bacterial endophytes grow symbiotically inside plants and improve the growth of their hosts. We evaluated the effects of inoculating macroalgae bacterial endophytes, introduced formerly by our group, Bacillus aquimaris strain OD14, B. megaterium strain AM25, B. zhangzhouensis strain Tv91C, individually and in combination with each other on the reactive oxygen species (ROS) of scavenging and antioxidant functions, as well as growth characteristics of Mexican lime seedlings under salinity stress. Accordingly, Mexican lime (Citrus aurant -ifolia Swingle.) seedlings were subjected to four salinity levels, i.e. 0, 2000, 4000 and 6000 µs cm-1 in the presence or absence of bacterial endophytes. The results indicated that salinity stress significantly reduced growth, chlorophyll, and carotenoid content of plants lacking endophytes. Combinatory applications with bacterial endophytes significantly improved the above-mentioned parameters under salinity stress. Lipid peroxidation levels were significantly reduced in plants inoculated with bacterial endophytes. Salinity stress significantly increased the activities of ascorbate peroxidase (APX), superoxide dismutase (SOD), glutathione reductase (GR), peroxidase (POD), and catalase (CAT) in salinity conditions. Overall, the inoculation with bacterial endophytes improved salinity tolerance and reduced the accumulation of ROS by increasing their scavenging via an enhanced redox state of glutathione and more effective antioxidant enzyme activities. [ABSTRACT FROM AUTHOR]

Copyright of Egyptian Journal of Botany is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Today, the use of biological fertilizers in sustainable agriculture is an appropriate alternative to chemical fertilizers because the former can improve the quantitative and qualitative performance of plants, especially under stressful conditions. Therefore, this study aims in greenhouse conditions to investigate the effects of plant growth-promoting rhizobacteria on antioxidant enzyme activities and some physiological traits of sweet basil under water limitation. For this purpose, a factorial experiment was conducted based on a completely randomized block design with three replications. Three levels of water deficit stress factor involved W0 = 100% of field capacity, W1= 60% of the field capacity, and W2 = 40% of the field capacity. Also, biofertilizers factor included nine levels of F1: Pota Barvar-2, F2: Phosphate Barvar-2, F3: Azeto Barvar 1, F4 (the combination of F1 and F2), F5 (the combination of F1 and F3), F6 (the combination of F2 and F3), F7 (the combination of F1, F2, and F3); F8 (100% chemical fertilizer as a positive control) and F9 (without any fertilizer as a negative control). Results showed that water limitation increased the activity of ascorbate peroxidase (193.55%), peroxidase (416.258%), polyphenol oxidase (48.21%) enzymes, and essential oil yield (135.48%). Meanwhile, the chlorophyll index, carotenoid, and yield decreased under water deficit stress. The use of biofertilizers improved these traits under water limitation conditions and normal irrigation. Also, applying a combination of 3 biofertilizers (F7) led to an increase 29.88% in the yield compared with negative control under severe water limitation. Therefore, the use of biofertilizer can be recommended for profitable basil production under water limitation conditions. [ABSTRACT FROM AUTHOR]

Both drought and high temperature can influence the antioxidant metabolism of crop reproductive organs in different ways, affecting the fertility of reproductive organs and yield formation. However, the combined effects of drought stress and high temperature on the crop reproductive physiology have not yet been widely considered. In order to broaden our understanding of this mechanism of influence, a pond experiment was conducted using a cotton variety Yuzaomian 9110 divided into four treatment groups: control (CK), drought stress (DS), high temperature (HT), and drought stress coupled with high temperature (DS+HT). Results showed a significant negative correlation between pollen viability and superoxide anion (O2−) content, as well as hydrogen peroxide (H2O2). Compared with CK, DS did not alter O2− content in anthers, but HT treatment resulted in higher anther O2−. Compared with single-stress groups, DS+HT further promoted the formation of O2− in anthers, leading to more malondialdehyde in anthers. Moreover, a higher H2O2 content in anthers was found in DS and HT than in CK. DS+HT did not show altered H2O2 content relative to HT treatment, although its H2O2 was higher than in DS. Further analyses of the antioxidant enzyme system showed that DS had no significant effect on superoxide dismutase gene (GhCu/ZnSOD) expression, but HT and DS+HT significantly downregulated its expression. The expression of GhCu/ZnSOD was lower under DS+HT than HT, which might be why O2− content was not altered under DS treatment compared with CK and was higher in DS+HT than HT. DS and HT significantly downregulated the expression of the peroxidase gene (GhPOD) and catalase gene (GhCAT), which should be the main reason for the larger accumulation of H2O2 under drought stress and high-temperature conditions. Compared with single-stress groups, DS+HT had lower expression of GhCAT, resulting in a larger H2O2 content. Regarding the ascorbic acid–glutathione (AsA–GSH) cycle, DS and HT significantly downregulated the expression of monodehydroascorbate reductase gene (GhMDHAR) to hinder the production of AsA and upregulated the expression of ascorbate oxidase gene (GhAAO) to promote the oxidation of AsA, which was theoretically detrimental to AsA accumulation. However, HT downregulated the expression of the ascorbate peroxidase gene (GhAPX), hindering the reduction of H2O2 by AsA, which was the reason for AsA and H2O2 accumulation. Moreover, DS also significantly upregulated the expression of the dehydroascorbate reductase gene (GhDHAR2) to enhance the reduction of dehydroascorbate to form AsA, leading to a higher content of AsA under DS than HT. The combined stress significantly downregulated the expression of GhAAO to inhibit the oxidation of AsA but significantly upregulated the expression of GhMDHAR and GhDHAR2, promoting the AsA production, and downregulated the expression of GhAPX, hindering the reduction of H2O2 by AsA. All these resulted in increased AsA content under combined stresses. In addition, HT significantly downregulated the glutathione reductase gene (GhGR) expression, hindering the reduction of oxidized glutathione (GSSG), which led to the reduction of GSH. However, DS and DS+HT significantly downregulated the glutathione peroxidase gene (GhGPX) expression, resulting in the accumulation of GSH. Overall, compared with single-stress treatments, the effects of DS+HT on cotton pollen fertility and peroxide accumulation were more significant. The effects of DS+HT on the antioxidant enzyme system were mainly caused by high temperature, while the mechanism of abnormal accumulation of AsA and GSH caused by DS+HT was different from those of single-stress groups. [ABSTRACT FROM AUTHOR]

This study focuses on developing and evaluating two novel enantioselective biomimetic models for the active centers of oxidases (ascorbate oxidase and catalase). These models aim to serve as alternatives to enzymes, which often have limited action and a delicate nature. For the ascorbate oxidase (AO) model (compound 1), two enantiomers, S,S(+)cpse and R,R(−)cpse, were combined in a crystalline structure, resulting in a racemic compound. The analysis of their magnetic properties and electrochemical behavior revealed electronic transfer between six metal centers. Compound 1 effectively catalyzed the oxidation of ascorbic to dehydroascorbic acid, showing a 45.5% yield for the racemic form. This was notably higher than the enantiopure compounds synthesized previously and tested in the current report, which exhibited yields of 32% and 28% for the S,S(+)cpse and R,R(-)cpse enantiomers, respectively. This outcome highlights the influence of electronic interactions between metal ions in the racemic compound compared to pure enantiomers. On the other hand, for the catalase model (compound 2), both the compound and its enantiomer displayed polymeric properties and dimeric behavior in the solid and solution states, respectively. Compound 2 proved to be effective in catalyzing the oxidation of hydrogen peroxide to oxygen with a yield of 64.7%. In contrast, its enantiomer (with R,R(-)cpse) achieved only a 27% yield. This further validates the functional nature of the prepared biomimetic models for oxidases. This research underscores the importance of understanding and designing biomimetic models of metalloenzyme active centers for both biological and industrial applications. These models show promising potential as viable alternatives to natural enzymes in various processes. [ABSTRACT FROM AUTHOR]

Persimmon fruits (Diospyros kaki L.) attract the attention of researchers due to their high nutritional and medicinal value. The composition of persimmon is rich in nutrients. The object of research is the storage technology of persimmon. Fully ripe persimmon varieties Khachia and Khiakume were used as research material. If the activity of enzymes is inhibited or reduced during refrigerated storage using a controlled gas environment, then the consumption of nutrients for respiration will decrease, and the fruits will retain their original appearance. The persimmon varieties used were stored in refrigerators for 5 months in five variants. In persimmon fruits of both varieties, quantitative changes in the main indicators during refrigerated storage were studied. The regularities of changes in the activity of enzymes of the oxidoructase class depending on the composition of the controlled gas medium and the content of phenolic compounds were considered. As a result of the analyzes, a rational regime for storing persimmon varieties in a refrigerator under CGE conditions with a gas composition of 3–4 % CO2 and 2–3 % O2, a temperature of ‒2...–3 °C and an air humidity of 90–95 % was determined. During the storage period, the activity of all enzymes, except for ascorbate oxidase, completely ceased (except for the catalase enzyme in the Khachia variety). During long-term storage of the Khachia variety in a refrigerator, the activity of the enzyme ascorbate oxidase decreased by 94 %, o-diphenol oxidase and peroxidase decreased by 100 %, catalase by 95.5 %. Ascorbate oxidase activity decreased by 94.5 % in persimmon fruits of the Khiakume variety, and the activity of other enzymes was completely inhibited. To achieve this result, it is important that the activity of oxidoreductases decreases or passes into an inhibitory state. The results make it possible to regulate the quality indicators of persimmon varieties depending on their storage modes and use them to provide people with fresh fruits not seasonally but for a long time. [ABSTRACT FROM AUTHOR]

Mangrove is one of the most precious ecosystems with the greatest losses due to climate change, human activities, and pollution. The objective of this study is to assess the accumulation and distribution of some trace metals (Cu, Cd, Ni, Pb, and Zn) in sediments and Avicennia marina roots and leaves and to discuss the antioxidant potential of A. marina under metallic pollution stress. Sediments, leaf, and root samples of A. marina were collected from five sites along the Red Sea Coast of Egypt. Several ecological pollution indices, including the geo accumulation index (Igeo), contamination factor (CF), pollution load index (PLI), bioconcentration factor (BCF), and translocation factor (TF), were used to assess the pollution load. Cu, Cd, Ni, Pb, and Zn average concentrations in sediments were 167.4, 0.75, 110.65, 39.79, and 220 μg g−1, respectively, and the average values of these metals in A. marina roots were 44.9, 0.5, 87.96, 39.02, and 54.68 μg g−1, respectively, while in leaves their concentration were 50.46, 0.5572, 88.24, 40.08, and 56.08 μg g−1, respectively. The values of the Igeo, CF, and PLI index indicated that location 1 and 5 are moderate-to-heavily contaminated sites. On the other hand, leaves and roots of A. marina grown in polluted locations 1 and 5 showed high accumulation of malondialdehyde (MDA), low chlorophyll a and chlorophyll b contents concomitant with a decrease in total soluble sugars. High total antioxidant capacity was associated with a significant increase in activity levels of antioxidant enzymes (Catalase, Polyphenol oxidase, Polyphenol peroxidase, and Ascorbic acid oxidase), accumulation of secondary metabolites (total phenols, flavonoids, and tannins), and proline and carotenoids content increase. Overall, the present study suggests that the mangrove habitat of the Egyptian Red Sea coast is under the stress of anthropogenic activities, which necessitates a conservation plan to avoid further contamination and protect the unique biota of this distinctive habitat. [ABSTRACT FROM AUTHOR]

Melatonin (MT) and nitric oxide (NO) act as signaling molecules that can enhance cadmium (Cd) stress resistance in plants. However, little information is available about the relationship between MT and NO during seedling growth under Cd stress. We hypothesize that NO may be involved in how MT responds to Cd stress during seedling growth. The aim of this study is to evaluate the relationship and mechanism of response. The results indicate that different concentrations of Cd inhibit the growth of tomato seedlings. Exogenous MT or NO promotes seedling growth under Cd stress, with a maximal biological response at 100 μM MT or NO. The promotive effects of MT-induced seedling growth under Cd stress are suppressed by NO scavenger 2-4-carboxyphenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (cPTIO), suggesting that NO may be involved in MT-induced seedling growth under Cd stress. MT or NO decreases the content of hydrogen peroxide (H2O2), malonaldehyde (MDA), dehydroascorbic acid (DHA), and oxidized glutathione (GSSG); improves the content of ascorbic acid (AsA) and glutathione (GSH) and the ratios of AsA/DHA and GSH/GSSG; and enhances the activities of glutathione reductase (GR), monodehydroascorbic acid reductase (MDHAR), dehydroascorbic acid reductase (DHAR), ascorbic acid oxidase (AAO), and ascorbate peroxidase (APX) to alleviate oxidative damage. Moreover, the expression of genes associated with the ascorbate–glutathione (AsA-GSH) cycle and reactive oxygen species (ROS) are up-regulated by MT or NO under Cd conditions, including AAO, AAOH, APX1, APX6, DHAR1, DHAR2, MDHAR, and GR. However, NO scavenger cPTIO reverses the positive effects regulated by MT. The results indicate that MT-mediated NO enhances Cd tolerance by regulating AsA-GSH cycle and ROS metabolism. [ABSTRACT FROM AUTHOR]

The major antioxidant L-ascorbic acid (AsA) plays important roles in plant growth, development, and stress responses. However, the importance of AsA concentration and the regulation of AsA metabolism in plant reproduction remain unclear. In Arabidopsis (Arabidopsis thaliana) anthers, the tapetum monolayer undergoes cell differentiation to support pollen development. Here, we report that a transcription factor, DEFECTIVE IN TAPETAL DEVELOPMENT AND FUNCTION 1 (TDF1), inhibits tapetal cell division leading to cell differentiation. We identified SKEWED5 - SIMILAR 18 (SKS18) as a downstream target of TDF1. Enzymatic assays showed that SKS18, annotated as a multicopper oxidase-like protein, has ascorbate oxidase activity, leading to AsA oxidation. We also show that VITAMIN C DEFECTIVE1 (VTC1), an AsA biosynthetic enzyme, is negatively controlled by TDF1 to maintain proper AsA contents. Consistently, either knockout of SKS18 or VTC1 overexpression raised AsA concentrations, resulting in extra tapetal cells, while SKS18 overexpression in tdf1 or the vtc1-3 tdf1 double mutant mitigated their defective tapetum. We observed that high AsA concentrations caused lower accumulation of reactive oxygen species (ROS) in tapetal cells. Overexpression of ROS scavenging genes in tapetum restored excess cell divisions. Thus, our findings demonstrate that TDF1-regulated AsA balances cell division and cell differentiation in the tapetum through governing ROS homeostasis. [ABSTRACT FROM AUTHOR]

Due to the distinguished medicinal value of Chrysobalanus icaco, it was of great interest to conduct phytochemical and antioxidant investigations on it. In this study, the polyphenol profile and antioxidant activity of C. icaco methanol crude extract and fractions were investigated. The crude extract of C. icaco was subjected to fractionation using methanol, n-hexane, ethyl acetate, and n-butanol as solvents. 2, 2-diphenyl-1picryl-hydrazyl (DPPH), 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and ferric ion reducing power (FRAP), ascorbate oxidase, total phenolic content, total flavonoids and polyphenol profile was determined using standard methods. A significant increase was observed in the DPPH radical scavenging activity, total flavonoids, total phenol, FRAP, ABTS, TAC and ascorbate oxidase of the crude extract when compared to methanol, ethyl acetate, n-hexane, n-butanol, and aqueous fractions. Polyphenols such as kaempferol, chlorogenic acid, catechin, quercetin, galic acid, pomolic acid, rutin, epicatechin, stigmasterol, sitosterol and caffeic acid were found in the different fractions. The total polyphenols content of different fractions of C icaco extract were as follows; methanol fraction > n-hexane fraction > ethyl acetate fraction > n-butanol fraction > aqueous fraction. The findings revealed that C icaco kernel could be used as a potent source of molecules with positive health attributes. [ABSTRACT FROM AUTHOR]

There is a complex interplay of biochemical interactions which determine the host plant reaction to herbivory. We studied the Chilo partellus-induced biochemical plant defense system in sorghum. Present studies found that the total protein, starch and total sugar contents were significantly lower, while antioxidant enzymes like ascorbate oxidase (AO), catalase (CAT), ascorbate peroxidase (APX), phenyl ammonia lyase (PAL), tyrosine ammonia lyase (TAL), and nonenzymatic antioxidants such as total phenols, total antioxidants and ferric ion reducing antioxidant power (FRAP) higher in the seedlings of all the test sorghum genotypes as compared to susceptible genotype, Swarna both under healthy and C. partellus damaged conditions. Further, the C. partellus damage resulted in significant increase in amounts of all the test constitutional, enzymatic and nonenzymatic biochemicals in the test genotypes, however their percent increase was highly variable across genotypes. These studies demonstrate that both constitutive and C. partellus damage induced enzymatic and nonenzymatic antioxidants like APX, AO, PAL, TAL, CAT, total phenols and FRAP were significantly greater in IS 2205, IS 18,551, ICSV 1, ICSV 700 and ICSV 93,046 than in susceptible check (Swarna) indicating their role in plant defense. Furthermore, these genotypes can be used in sorghum breeding for resistance against C. partellus. [ABSTRACT FROM AUTHOR]

In this study, a copper hexacyanoferrate nanoparticle with excellent oxidase-mimetic behaviour has been synthesized through a simple precipitation method. The synthesized copper hexacyanoferrate nanoparticle has intrinsic oxidase-like activity, which can catalyze the chromogenic reaction of 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) through an O2•− reactive oxygen-species-participated process. On the other hand, K3[Fe(CN)6] can be reduced by ascorbic acid (AA) to produce K4[Fe(CN)6], thereby inhibiting the formation of the copper hexacyanoferrate nanoparticles. Furthermore, ascorbate oxidase (AAO) can catalyze the oxidation of AA to produce dehydroascorbic acid, which cannot reduce K3[Fe(CN)6]. Thus, a system for an AAO-regulated in situ formation of copper hexacyanoferrate nanoparticles was constructed by coupling a prepared copper hexacyanoferrate nanozyme with AA for the detection of AAO activity. This colorimetric sensing assay shows high sensitivity and selectivity for the detection of AAO activity (the limit of detection is 0.52 U/L) with a linear range of 1.1–35.7 U/L. Finally, the developed method was applied to detect the activity of AAO in normal human serum with a satisfactory sample spiked recovery (87.4–108.8%). In short, this study provides a good strategy for the construction of nanozyme-based multi-enzyme cascade-signal amplification assay. [ABSTRACT FROM AUTHOR]

By using jasmonic acid (JA) biosynthetic inhibitor ibuprofen (IBU), we investigated the roles of JA in the process of lanthanum nitrate (La(NO3)3)-regulated ascorbic acid (AsA) content and metabolic enzymes responsible for AsA metabolism in strawberry fruit. Findings demonstrated that La(NO3)3 markedly improved AsA content by enhancing the activities and transcript levels of glutathione reductase (GR), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and l-galactono-1,4-lactone dehydrogenase (GalLDH), and inhibiting the activities and transcript levels of ascorbate peroxidase (APX) and ascorbic acid oxidase (AAO). In comparison with La(NO3 )3 alone, all the concentrations of IBU plus La(NO3)3 markedly inhibited the activities and transcript levels of DHAR, MDHAR, GalLDH and AAO and improved the activities and transcript levels of GR and APX, which further reduced AsA content. Besides, La(NO3)3 increased JA content, and IBU decreased JA content induced by La(NO3)3. Meanwhile, the results of Pearson correlation analysis showed that JA content had significant correlations with the activities and transcript levels of DHAR, MDHAR and GalLDH. Above findings implied that La(NO3)3 induced JA production, which further increased AsA content in fruits by mainly up-regulating the activities and transcript levels of DHAR, MDHAR and GalLDH. [ABSTRACT FROM AUTHOR]

Nanomaterials with intrinsic enzyme mimicking activity have achieved widespread application. However, developing novel nanomaterials with multienzyme mimicry activity remains challenging. Herein, Cu 3 (HITP) 2 (HITP = 2,3,6,7,10,11-hexaiminotriphenylene) with ascorbic acid oxidase (AAO)- and peroxidase (POD)-like activity are successfully synthesized. Cu 3 (HITP) 2 exhibits excellent AAO-like activity and can specifically catalyze the oxidation reaction of ascorbic acid (AA). Dehydroascorbic acid (DHAA) obtained from the oxidation of AA is allowed to react with nonfluorescent o -phenylenediamine (OPD) to form 3-(1,2-dihydrox-yethyl) furo[3,4- b ]quinoxaline-1-one (DFQ) with strong fluorescence emission. Moreover, Cu 3 (HITP) 2 is able to catalyze the chemiluminescence (CL) reaction of ABEI-H 2 O 2 to generate a strong and glow-type emission based on its POD activity. Inspired by the multienzyme mimicry activity of Cu 3 (HITP) 2 , the simple and sensitive fluorescence and chemiluminescence sensing platforms are successfully constructed and applied for the detection of AA. The sensors show high sensitivity and excellent selectivity. We believe that this multienzyme mimicry activity nanomaterial not only can be used to construct the multiple-mode biosensing platform, but also enables the extensive applications in the fields of biomedicine, energy, and environment. [Display omitted] • Cu 3 (HITP) 2 was synthesized, which exhibits peroxidase (POD)- and ascorbic acid oxidase (AAO)-like activity. • The strong and glow-type chemiluminescence sensing system was constructed utilizing the POD-like activity of Cu 3 (HITP) 2. • Fluorescence sensing platform was established based on AAO-like activity of Cu 3 (HITP) 2. • The sensors displayed excellent performance in terms of simplicity, sensitivity, and specificity. [ABSTRACT FROM AUTHOR]

[Display omitted] • MXenes-based metal composites were prepared by a molten salt method. • A simple colorimetric sensor for the detection of phenolic pollutants was constructed. • A hydrogel-assisted sensing platform was formed to detect phenolic pollutants. Phenolic pollutants are commonly employed in industries such as petrochemicals, dyeing, textiles, and pesticides, which cause great harm to our living environment and food safety. In this paper, the MXenes-based metal composites (M/MXenes, M = Cu, Co, Ni, Zn, Fe, Mn) with multi-enzyme mimic activity were prepared by a facile molten salt method. The M/MXenes have mimic catalytic activity of peroxidase (POD), ascorbic acid oxidase (AAO), catalase (CAT), superoxide dismutase (SOD) and laccase. The catalytic properties of M/MXenes were analyzed and discussed in detail. In addition, M/MXenes still have excellent catalytic performance and stability in harsh pH and high temperature environments, making them very suitable for practical applications. Due to the excellent laccase mimic activity of M/MXenes, a simple colorimetric sensor was constructed for the detection and degradation of phenolic pollutants. Because obvious color changes can be observed during the catalytic process of phenolic pollutants by M/MXenes, M/MXenes were fixed into sodium alginate (SA) to form a simple hydrogel-based sensing platform for 2, 4-chlorophenol, methoxyphenol, 4-bromophenol, 3-bromo-4-methoxyphenol, 3-bromo-4-methylphenol, hydroquinone and 1,8-naphthol. By introducing different concentrations of phenolic compounds, a series of color changes on the gel carrier can be observed by naked eyes. Then, the red (R), green (G) and blue (B) values matching with the color change of the hydrogel were read out by the color recognition application in the smartphone, and the RGB value was converted into the concentration of phenolic compounds, which offered a convenient and reliable method for the rapid detection of phenolic compounds. Thus, the strategy offers the potential in rational design of nanozymes with the advantages of multi-enzyme mimic activity, simple preparation, low cost and good stability. [ABSTRACT FROM AUTHOR]

Human immunoglobulin (HIgG) has gained recognition as a crucial biomarker diagnosing and treating various diseases, particularly in identifying elevated serum levels in conditions like measles and pneumococcal disease. Traditional detection methods, however, are often hindered by inefficiencies, high costs, and potential inaccuracies, underscoring the urgent need for more sensitive, efficient, accurate, and self-calibration methods for HIgG. Here, a novel ZnIn 2 S 4 /SnO 2 composites was synthesized, featuring uniformly dispersed SnO 2 nanoparticles on the flower-like ZnIn 2 S 4 structure, resulting in a type II heterojunction that promotes the separation and transfer of photogenerated carriers. Under optimized conditions, this composite demonstrated remarkable photocurrent enhancements 52 and 195 times greater than that of the individual ZnIn 2 S 4 or SnO 2 , respectively. A novel dual-mode biosensing platform was subsequently developed, employing the ZnIn 2 S 4 /SnO 2 composites as both as the photoelectrochemical (PEC) signal generator and antibody carrier. This system utilizes multifunctional CuO NPs with ascorbic acid oxidase-like properties, serving as a secondary antibody label. Upon specific binding to HIgG, a notable decrease in the PEC response occurs due to the catalytic activity of CuO NPs and the antigen-antibody interactions. The introduction of o -phenylenediamine (OPD) further enhances detection by facilitating the formation of a fluorescent substance DHAA. This dual-signal approach yielded excellent linear correlations between both PEC and fluorescence signals and HIgG concentration, achieving low detection limits of 22.5 pg/mL or 8.6 pg/mL. These two signals originated from the same PEC electrode with continuous detection in the absence and presence of OPD, simplifying experimental procedures and enhancing the reliability of detection. The non-toxic, chemically stable ZnIn 2 S 4 /SnO 2 composites ensures reliable and sensitive detection through photocurrent output after incubation with biomolecules. The integration of nanozyme catalysis, biospecific reactions, and in situ fluorescent products generation promise high selectivity across diverse immunosensing applications. [Display omitted] • A novel dual-channel biosensing platform has been developed for HIgG. • ZnIn 2 S 4 /SnO 2 composites offer superior and stable photoelectrochemical signals. • Multifunctional CuO NPs serves as a nanozyme and nanocarrier for antibody. • The dual-channel signals derived from the same PEC for continuous detection. • The PEC and FL was triggered by specific immune and nanozyme-catalyzed reaction. [ABSTRACT FROM AUTHOR]

This study aimed to explore how exogenous proline induces salinity tolerance in celery. We analyzed the effects of foliar spraying with 0.3 mM proline on celery growth, photosystem, phenolic compounds, and antioxidant system under salt stress (100 mM NaCl), using no salt stress and no proline spraying as control. The results showed that proline-treated plants exhibited a significant increase in plant biomass due to improved growth physiology, supported by gas exchange parameters, chlorophyll fluorescence, and Calvin cycle enzyme activity (Ketosasaccharide-1,5-diphosphate carboxylase and Fructose-1,6-diphosphate aldolase) results. Also, proline spraying significantly suppressed the increase in relative conductivity and malondialdehyde content caused by salt stress, suggesting a reduction in biological membrane damage. Moreover, salt stress resulted in hydrogen peroxide, superoxide anions and 4-coumaric acid accumulation in celery, and their contents were reduced after foliar spraying of proline. Furthermore, proline increased the activity of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) and the content of non-enzymatic antioxidants (reduced ascorbic acid, glutathione, caffeic acid, chlorogenic acid, total phenolic acids, and total flavonoids). Additionally, proline increased the activity of key enzymes (ascorbate oxidase, ascorbate peroxidase, glutathione reductase, and dehydroascorbate reductase) in the ascorbic acid–glutathione cycle, activating it to counteract salt stress. In summary, exogenous proline promoted celery growth under salt stress, enhanced photosynthesis, increased total phenolic acid and flavonoid contents, and improved antioxidant capacity, thereby improving salt tolerance in celery. [ABSTRACT FROM AUTHOR]

To understand the effect of ultraviolet (UV)-B irradiation on the antioxidant capacity and growth of lettuce (Lactuca sativa), we subjected lettuce plants to UV-B irradiation (15.55 kJ m−2 d−1) for 7 days and measured yield, photosynthetic performance, hydrogen peroxide (H2O2), reduced glutathione (GSH), and ascorbic acid (AsA) contents, and the enzyme activity and expression of genes involving AsA recycling. UV-B exposure did not significantly decrease the fresh/dry weight of the lettuce shoots. The net photosynthesis rate, internal CO2 concentration, transpiration rate, and stomatal conductance decreased during the first 4 days of irradiation and light but recovered at day 7. In UV-B-treated plants, the levels of AsA, GSH, and H2O2 increased significantly and simultaneously, with a positive correlation found between H2O2 and AsA or GSH levels. UV-B exposure upregulated the expression level of most genes encoding the enzymes involving AsA recycling but downregulated the associated enzymatic activities. The increase of AsA content in UV-B-exposed lettuce might contribute to the AsA–GSH cycle, leading to downregulation of ascorbate oxidase (AO) enzymatic activity and gene expression. UV-B irradiation had a greater impact on metabolite levels than time of UV-B treatment. These results suggest that AsA homeostasis in UV-B-treated lettuce is regulated through a feedback loop between the expression and activity of enzymes associated with AsA recycling. Short-term UV-B supplementation (24 h) could be a promising approach to enhance AsA content in lettuce. [ABSTRACT FROM AUTHOR]

The uplift of the Qinghai Tibet Plateau has led to a drastic change in the climate in Central Asia, from warm and rainy, to dry and less rainfall. Ammopiptanthus nanus, a rare evergreen broad-leaved shrub distributed in the temperate desert region of Central Asia, has survived the drastic climate change in Central Asia caused by the uplift of the Qinghai-Tibet Plateau. Ascorbate oxidase (AO) regulates the redox status of the apoplast by catalyzing the oxidation of ascorbate acid to dehydroascorbic acid, and plays a key role in the adaptation of plants to environmental changes. Analyzing the evolution, environmental response, and biological functions of the AO family of A. nanus is helpful for understanding how plant genome evolution responds to climate change in Central Asia. A total of 16 AOs were identified in A. nanus, all of which contained the ascorbate oxidase domain, most of which contained transmembrane domain, and many were predicted to be localized in the apoplast. Segmental duplication and tandem duplication are the main factors driving the gene amplification of the AO gene family in A. nanus. Gene expression analysis based on transcriptome data and fluorescence quantitative PCR, as well as enzyme activity measurements, showed that the expression levels of AO genes and total enzyme activity decreased under short-term osmotic stress and low-temperature stress, but the expression of some AO genes (AnAO5, AnAO13, and AnAO16) and total enzyme activity increased under 7 days of cold stress. AnAO5 and AnAO11 are targeted by miR4415. Further functional studies on AnAO5 showed that AnAO5 protein was localized in the apoplast. The expression of AnAO5 in yeast cells and the transient expression in tobacco enhanced the tolerance of yeast and tobacco to low-temperature stress, and the overexpression of AnAO5 enhanced the tolerance of Arabidopsis seedlings to cold stress. Our research provides important data for understanding the role of AOs in plant adaptation to environmental change. [ABSTRACT FROM AUTHOR]

Herein, a Co–Fe Prussian blue analogue nanocube (Co–Fe PBA NC) was prepared in situ via a simple and rapid coprecipitation method at room temperature, and the synthesized nanocube was systematically characterized. The Co–Fe PBA NC was proven to have intrinsic oxidase-like activity, which can catalyze the production of reactive oxygen species, such as superoxide anions (O2˙−), hydroxyl radicals (˙OH), and singlet oxygen (1O2), in a dissolved oxygen system without the presence of hydrogen peroxide (H2O2). By making full use of the oxidase-like activity of the Co–Fe PBA NC and using the chromogenic substrate 3,3′,5,5′-tetramethylbenzidine (TMB), a colorimetric sensor was fabricated for the detection of ascorbic acid (AA) and its related biological enzymes' activities, including alkaline phosphatase (ALP), α-glucosidase (α-Glu), and ascorbic acid oxidase (AAO), in human serum. This study presents an oxidase mimic that can be synthesized via a simple, rapid, and low-cost method, which overcomes the defects of cumbersome and time-consuming synthetic process, dependence on professional instruments and high cost of some previously reported nanozymes. In addition, this study provides a new multifunctional colorimetric sensing platform for AA and its related biological enzymes, showing great potential in biological assays. [ABSTRACT FROM AUTHOR]

This study considers determining the quality indicators of table grape varieties when stored in a refrigerating chamber for different variants. The objects were white table grape variety, widely used in Azerbaijan, Ganja table grape variety, pink grape variety - Marandi Shamakhi, as well as the red grape variety Black Asma. Grape varieties stored in the refrigerator were studied according to five options. Table grape varieties were stored in a refrigerating chamber under conditions of an adjustable gas environment (3-4 % CO2, 2-3 % О2) at a temperature of -1 and -2 °C, with air humidity of 90-95 %. It was found that at a temperature inside the pulp of 0+1 °C, the activity of enzymes decreased significantly compared to other options. In addition to the enzyme ascorbate oxidase, the activity of the studied enzymes o-diphenol oxidase, peroxidase, and catalase was 100 % suppressed in the Marandi Shamakhi grape variety. The inactivation of enzyme activity prevented the consumption during respiration of the nutrients that make up the grapes. As a result of slowing down metabolic processes, the appearance, naturalness, and nutritional value of the Marandi Shamakhi grape variety are significantly superior to other varieties. When storing grape varieties according to option 5, the smallest total losses were observed in the Marandi Shamakhi grape variety. Very few microbiological losses were detected during the storage of the Marandi Shamakhi grape variety compared to other variants and varieties. It was stored in a refrigerating chamber in a controlled gas environment (3...4 % CO2, 2-3 % О2, at the temperature of the chamber of -2...-3 °C). A tasting was also carried out to determine the quality indicators when storing grape varieties in different versions; for version 5, the assessment was high. [ABSTRACT FROM AUTHOR]

Ever since the identification of vitamin C (ascorbic acid, AsA) as an essential molecule that humans cannot synthesize on their own, finding adequate dietary sources of AsA became a priority in nutrition research. Plants are the main producers of AsA for humans and other non-synthesizing animals. It was immediately clear that some plant species have more AsA than others. Further studies evidenced that AsA content varies in different plant organs, in different developmental stages/environmental conditions and even within different cell compartments. With the progressive discovery of the genes of the main (Smirnoff-Wheeler) and alternative pathways coding for the enzymes involved in AsA biosynthesis in plants, the simple overexpression of those genes appeared a suitable strategy for boosting AsA content in any plant species or organ. Unfortunately, overexpression experiments mostly resulted in limited, if any, AsA increase, apparently due to a tight regulation of the biosynthetic machinery. Attempts to identify regulatory steps in the pathways that could be manipulated to obtain unlimited AsA production were also less successful than expected, confirming the difficulties in “unleashing” AsA synthesis. A different approach to increase AsA content has been the overexpression of genes coding for enzymes catalyzing the recycling of the oxidized forms of vitamin C, namely monodehydroascorbate and dehydroascorbate reductases. Such approach proved mostly effective in making the overexpressors apparently more resistant to some forms of environmental stress, but once more did not solve the issue of producing massive AsA amounts for human diet. However, it should also be considered that a hypothetical unlimited increase in AsA content is likely to interfere with plant development, which is in many ways regulated by AsA availability itself. The present review article aims at summarizing the many attempts made so far to improve AsA production/content in plants, evidencing the most promising ones, and at providing information about the possible unexpected consequences of a pure biotechnological approach not keeping into account the peculiar features of the AsA system in plants. [ABSTRACT FROM AUTHOR]

Ever since the identification of vitamin C (ascorbic acid, AsA) as an essential molecule that humans cannot synthesize on their own, finding adequate dietary sources of AsA became a priority in nutrition research. Plants are the main producers of AsA for humans and other non-synthesizing animals. It was immediately clear that some plant species have more AsA than others. Further studies evidenced that AsA content varies in different plant organs, in different developmental stages/environmental conditions and even within different cell compartments. With the progressive discovery of the genes of the main (Smirnoff-Wheeler) and alternative pathways coding for the enzymes involved in AsA biosynthesis in plants, the simple overexpression of those genes appeared a suitable strategy for boosting AsA content in any plant species or organ. Unfortunately, overexpression experiments mostly resulted in limited, if any, AsA increase, apparently due to a tight regulation of the biosynthetic machinery. Attempts to identify regulatory steps in the pathways that could be manipulated to obtain unlimited AsA production were also less successful than expected, confirming the difficulties in “unleashing” AsA synthesis. A different approach to increase AsA content has been the overexpression of genes coding for enzymes catalyzing the recycling of the oxidized forms of vitamin C, namely monodehydroascorbate and dehydroascorbate reductases. Such approach proved mostly effective in making the overexpressors apparently more resistant to some forms of environmental stress, but once more did not solve the issue of producing massive AsA amounts for human diet. However, it should also be considered that a hypothetical unlimited increase in AsA content is likely to interfere with plant development, which is in many ways regulated by AsA availability itself. The present review article aims at summarizing the many attempts made so far to improve AsA production/content in plants, evidencing the most promising ones, and at providing information about the possible unexpected consequences of a pure biotechnological approach not keeping into account the peculiar features of the AsA system in plants.

Ascorbate oxidase, which is known to play a key role in regulating the redox state in the apoplast, cell wall metabolism, cell expansion and abiotic stress response in plants, oxidizes apo-plastic ascorbic acid (AA) to dehydroascorbic acid (DHA). However, there is little information about the AAO genes and their functions in beets under abiotic stress. The term salt or drought stress refers to the treatment of plants with slow and gradual salinity/drought. Contrastingly, salt shock consists of exposing plants to high salt levels instantaneously and drought shock occurs under fast drought progression. In the present work, we have subjected plants to salinity or drought treatments to elicit either stress or shock and carried out a genome-wide analysis of ascorbate oxidase (AAO) genes in sugar beet (B. vulgaris cv. Huzar) and its halophytic ancestor (B. maritima). Here, conserved domain analyses showed the existence of twelve BvAAO gene family members in the genome of sugar beet. The BvAAO_1–12 genes are located on chromosomes 4, 5, 6, 8 and 9. The phylogenetic tree exhibited the close relationships between BvAAO_1-12 and AAO genes of Spinacia oleracea and Chenopodium quinoa. In both beet genotypes, downregulation of AAO gene expression with the duration of salt stress or drought treatment was observed. This correlated with a decrease in AAO enzyme activity under defined experimental setup. Under salinity, the key downregulated gene was BvAAO_10 in Beta maritima and under drought the BvAAO_3 gene in both beets. This phenomenon may be involved in determining the high tolerance of beet to salinity and drought. [ABSTRACT FROM AUTHOR]