Untargeted metabolomics-based identification of bioactive compounds from Mangifera indica L. seed extracts in drug discovery through molecular docking and assessment of their anticancer potential.

BACKGROUND: Mangifera indica L. (mango), a medicinal plant rich in biologically active compounds, has potential to be used in disease-preventing and health-promoting products. The present investigation reveals and uncovers bioactive metabolites with remarkable therapeutic efficiency from mango (family: Anacardiaceae) seeds. RESULTS: Biological activity was determined by antimicrobial, antioxidant and anticancer assays, and metabolite profiling was performed on gas chromatography coupled to quadrupole time-of-flight mass spectrometry (GC-QTOF-MS) and liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) platforms. Validation of active metabolites was carried out by in silico molecular docking (Molinspiration Cheminformatics Server and PASS). Extracted and identified metabolites were screened; 54 compounds associated with various groups were selected for the in silico interaction study. CONCLUSIONS: Molecular docking revealed lead molecules with a potential binding energy score, efficacy and stable modulation with a selected protein domain. Investigation, directed by in vitro and in silico analysis, confirms mango seeds as an excellent source of potential metabolites as a therapeutic agent. © 2024 Society of Chemical Industry.

Spirulina (Arthrospira platensis) supplementation: Impact on growth, metabolism, and antioxidant status in zebrafish.

Zebrafish (Danio rerio) is a valuable model for biomedical research because of its mammalian genetic similarities, rapid reproduction, and low maintenance costs. However, further investigation is required regarding their nutritional requirements and standardized laboratory diets. This study evaluated the metabolic and growth responses of zebrafish juveniles fed on diets supplemented with spirulina, Arthrospira platensis (SP) at different levels for 77 days. Six diets with SP inclusion levels of 0%, 2%, 4%, 6%, 8%, and 10% (SP0-SP10) were formulated. A total of 300 zebrafish juveniles with an average initial weight of 0.113 ± 0.10 g (mean ± SD) were randomly distributed across six groups, with five replicates per group, each containing 10 animals. After 77 days, the SP6 group demonstrated significantly enhanced growth performance compared with the other supplementation levels. The condition factor was markedly higher in the SP6 and SP8 groups than in the SP0 group. No significant effects on total cholesterol levels were observed, but the SP4, SP6, and SP10 diets decreased triglyceride levels. Lipase activity was higher in the SP6 and SP8 groups than in the control group, whereas amylase activity showed no significant differences between treatments. Catalase and superoxide dismutase activities were significantly higher in the SP8 and SP10 groups than in the SP0 and SP2 groups. Glutathione S-transferase activity was higher in the SP6, SP8, and SP10 groups than in the SP0 group. In addition, SP inclusion in zebrafish diets improved female gonadal development. In conclusion, this study indicates that SP supplementation has substantial potential as a growth promoter, positively influencing lipid metabolism and antioxidant enzyme activity without affecting zebrafish survival.

External application of brassinolide enhances cold resistance of tea plants (Camellia sinensis L.) by integrating calcium signals.

MAIN CONCLUSION: Exogenous brassinolide can activate the expression of key genes in the calcium signalling pathway to enhance cold resistance of tea plants. Brassinolide is an endogenous sterol phytohormone containing multiple hydroxyl groups that has the important function of improving plant cold resistance and alleviating freeze damage. To explore the molecular mechanism of how brassinolide improves the cold resistance of tea plants, "Qiancha 1" was used as the material, and the method of spraying brassinolide on the leaves was adopted to explore its effects on the tea plants under 4 °C low-temperature treatment. The results showed that brassinolide can significantly increase the protective enzyme activity of tea plants under cold stress and reduce cold damage. At the transcriptome level, brassinolide significantly enhanced the expression of key genes involved in calcium signal transduction, Calmodulin (CaM), Calcium-dependent protein kinase (CDPK), calcineurin B-like protein (CBL) and calmodulin-binding transcriptional activators (CAMTA), which then activated the downstream key genes transcriptional regulator CBF1 (CBF1) and transcription factor ICE1 (ICE1) during cold induction. Quantitative real-time PCR (qRT‒PCR) results showed that the expression of these genes was significantly induced after treatment with brassinolide, especially CaM and CBF1. When calcium signalling was inhibited, the upregulated expression of CBF1 and ICE1 disappeared, and when CAMTA was knocked down, the expression of other genes under cold stress was also significantly reduced. The above results indicate that brassinolide combined with the calcium signalling pathway can improve the cold resistance of tea plants. This study provides a new theoretical basis for the study of the cold resistance mechanism of brassinolide.

Molecular characterization and evolution of the resident population of some alfalfa mosaic virus (AMV) isolates in Egypt.

BACKGROUND: Alfalfa mosaic virus (AMV) is an important virus affecting many vegetable crops in Egypt. In this study, virus isolates were collected from naturally infected potato, tomato, alfalfa and clover plants that showed suspected symptoms of AMV in different locations of Beheira and Alexandria governorates during the 2019-2020 growing season. The relative incidence of the virus ranged from 11-25% based on visual observations of symptoms and ELISA testing. A total of 41 samples were tested by ELISA using polyclonal antisera for AMV. Four AMV isolates collected from different host plants, named AM1 from potato, AM2 from tomato, AM3 from alfalfa and AM4 from alfalfa, were maintained on Nicotiana glutinosa plants for further characterization of AMV. RESULTS: Electron micrographs of the purified viral preparation showed spheroidal particles with a diameter of 18 nm and three bacilliform particles with lengths of roughly 55, 68, and 110 nm and diameters identical to those of the spheroidal particles. The CP gene sequence comparisons of four AMV isolates (AM1, AM2, AM3 and AM4) showed the highest nucleotide identity of 99.7% with the Gomchi isolate from South Korea infecting Gomchi (Ligularia fischeri) plants. Phylogenetic analysis showed that the present isolates were grouped together into a distinct separate clade (GPI) along with the Gomchi isolate from South Korea. Similarly, the deduced amino acid sequence comparisons of Egyptian AMV isolates revealed that amino acids Q29, S30, T34, V92 and V175 were conserved among the Egyptian isolates in GPI. CONCLUSION: The present study found strong evolutionary evidence for the genetic diversity of AMV isolates by the identification of potential recombination events involving parents from GPI and GPII lineages. Additionally, the study found that Egyptian AMV isolates are genetically stable with low nucleotide diversity. Genetic analysis of the AMV population suggested that the AMV populations differ geographically, and AMV CP gene is under mild purifying selection. Furthermore, the study proposed that the Egyptian AMV population had common evolutionary ancestors with the Asian AMV population. Antioxidant enzymes activity was assessed on N. glutinosa plants in response to infection with each AMV isolate studied, and the results revealed that the enzyme activity varied.

Impact of silver ions and silver nanoparticles on biochemical parameters and antioxidant enzyme modulations in Saccharomyces cerevisiae under co-exposure to static magnetic field: a comparative investigation.

The increase in simultaneous exposure to magnetic fields and other hazardous compounds released from industrial applications poses multiple stress conditions on the ecosystems and public human health. In this work, we investigated the effects of co-exposure to a static magnetic field (SMF) and silver ions (AgNO3) on biochemical parameters and antioxidant enzyme activities in the yeast Saccharomyces cerevisiae. Sub-chronic exposure to AgNO3 (0.5 mM) for 9 h resulted in a significant decrease in antioxidant enzyme activity, including glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD), and glutathione transferase (GST). The total glutathione (GSH) level increased in yeast cells exposed to Ag. Additionally, a notable elevation in malondialdehyde (MDA) levels and protein carbonyl content was observed in both the AgNP and AgNO3 groups compared to the control group. Interestingly, the SMF alleviated the oxidative stress induced by silver nitrate, normalizing antioxidant enzyme activities by reducing cellular ROS formation, MDA levels, and protein carbonylation (PCO) concentrations.

Concentration-dependent mechanisms of fluoranthene uptake by ryegrass.

Fluoranthene (Flu) uptake by plants is affected by plant growth and environmental concentration. Although plant growth processes, including substance synthesis and antioxidant enzyme activities, have been reported to regulate Flu uptake, their contributions have been poorly evaluated. Moreover, the effect of Flu concentration is little known. Here, low concentrations (0, 1, 5, and 10 mg/L) and high concentrations (20, 30, and 40 mg/L) of Flu were set to compare the changes in Flu uptake by ryegrass (Lolium multiflorum Lam.). Indices of plant growth (biomass, root length, root area, root tip number, and photosynthesis and transpiration rates), substance synthesis (indole acetic acid [IAA] content), and antioxidant enzyme activities (superoxide dismutase [SOD], peroxidase [POD], and catalase [CAT]) were recorded to unravel the mechanism of Flu uptake. Findings suggested that the Langmuir model fitted Flu uptake by ryegrass well. Flu absorption capacity in the root was stronger than that that in the leaf. Flu bioconcentration and translocation factors increased then reduced with the increase in Flu concentration and reached the maximum value under 5 mg/L Flu treatment. Plant growth and IAA content had the same pattern as before bioconcentration factor (BCF). SOD and POD activities increased then decreased with Flu concentration and reached their highest levels under 30 and 20 mg/L Flu treatments, respectively, whereas CAT activity decreased continuously and reached its lowest level under 40 mg/L Flu treatment. Variance partitioning analysis indicated that IAA content had the greatest significant effect on Flu uptake under low-concentration Flu treatments, whereas antioxidant enzyme activities had the greatest significant effect on Flu uptake under high-concentration Flu treatments. Revealing the concentration-dependent mechanisms of Flu uptake could provide a basis for regulating pollutant accumulation in plants.

Physiological response of Kobresia pygmaea to temperature changes on the Qinghai-Tibet Plateau.

BACKGROUND: The Qinghai-Tibetan Plateau is experiencing rapid climate warming, which may further affect plant growth. However, little is known about the plant physiological response to climate change. RESULTS: Here, we select the Kobresia pygmaea, an important perennial Cyperaceae forage, to examine the physiological indices to temperature changes in different growing months. We determined the contents of malondialdehyde, proline, soluble sugars, superoxide dismutase, peroxidation, and catalase activity in leaves and roots of Kobresia pygmaea at 25℃, 10℃, 4℃ and 0℃ from June to September in 2020. The results showed that the content of osmotic adjustment substances in the leaves and roots of Kobresia pygmaea fluctuated greatly with experimental temperature in June and September. The superoxide dismutase activity in the leaves and roots of the four months changed significantly with temperatures. The peroxidation activity in the leaves was higher than that in the roots, while the catalase activity in leaves and roots fluctuates greatly during June, with a relative stable content in other months. Membership function analysis showed that higher temperatures were more harmful to plant leaves, and lower temperatures were more harmful to plant roots. The interaction of organs, growing season and stress temperature significantly affected the physiological indicators. CONCLUSIONS: The physiological indicators of Kobresia pygmaea can actively respond to temperature changes, and high temperature can reduce the stress resistance Kobresia pygmaea. Our findings suggest that the Kobresia pygmaea has high adaptability to climate warming in the future.

Ecotoxicological Impact of the Marine Toxin Palytoxin on the Micro-Crustacean Artemia franciscana.

Palytoxin (PLTX) is a highly toxic polyether identified in various marine organisms, such as Palythoa soft corals, Ostreopsis dinoflagellates, and Trichodesmium cyanobacteria. In addition to adverse effects in humans, negative impacts on different marine organisms have been often described during Ostreopsis blooms and the concomitant presence of PLTX and its analogues. Considering the increasing frequency of Ostreopsis blooms due to global warming, PLTX was investigated for its effects on Artemia franciscana, a crustacean commonly used as a model organism for ecotoxicological studies. At concentrations comparable to those detected in culture media of O. cf. ovata (1.0-10.0 nM), PLTX significantly reduced cysts hatching and induced significant mortality of the organisms, both at larval and adult stages. Adults appeared to be the most sensitive developmental stage to PLTX: significant mortality was recorded after only 12 h of exposure to PLTX concentrations > 1.0 nM, with a 50% lethal concentration (LC50) of 2.3 nM (95% confidence interval = 1.2-4.7 nM). The toxic effects of PLTX toward A. franciscana adults seem to involve oxidative stress induction. Indeed, the toxin significantly increased ROS levels and altered the activity of the major antioxidant enzymes, in particular catalase and peroxidase, and marginally glutathione-S-transferase and superoxide dismutase. On the whole, these results indicate that environmentally relevant concentrations of PLTX could have a negative effect on Artemia franciscana population, suggesting its potential ecotoxicological impact at the marine level.

Monoculture and co-culture tests of the toxicity of four typical herbicides on growth, photosynthesis and oxidative stress responses of the marine diatoms Pseudo-nitzschia mannii and Chaetoceros decipiens.

The toxicity of four herbicides in mixture (alachlor, diuron, des-isopropyl-atrazine and simazine) on the growth and the photosynthesis parameters of two marine diatoms Pseudo-niszchia mannii and Chaetoceros decipiens have been investigated for 9 days in monoculture and co-culture tests. The catalase (CAT) and guaiacol peroxidase (GPX) were also monitored to assess the oxidative stress response. In single-species assays, while both species displayed no affected instantaneous growth rate by herbicides, their physiological responses were different. Chl a content of P. mannii significantly decreased upon herbicide exposure, due probably to pigment destruction or inhibition of their synthesis. This decrease was associated with a reduction in the chlorophyll fluorescence parameters (ABS0/RC, TR0/RC, ET0/RC and DI0/RC). In contrast, C. decipiens maintained an effective photosynthetic performance under herbicide exposure, as Chl a per cell content and the specific energy fluxes per reaction center remained unchanged relative to control values. GPX activity was significantly higher in contaminated P. mannii and C. decipiens monocultures than in controls at early herbicide exposure (1 day), whereas a significant induction of CAT activity occurred later (from day 3 for C. decipiens and at day 9 for P. mannii) in response to herbicides. In control co-culture, P. mannii was eliminated by C. decipiens. As observed in the monoculture, the herbicides did not affect the photosynthetic performance of C. decipiens in co-culture, but significantly reduced its instantaneous growth rate. The oxidative stress response in co-culture has similar trends to that of C. decipiens in monoculture, but the interspecies competition likely resulted in higher CAT activity under herbicide exposure. Results of this study suggest that herbicide toxicity for marine diatoms might be amplified by interspecies interactions in natural communities, which might lead to different physiological and growth responses.

Physiological and Biochemical Parameters of Salinity Resistance of Three Durum Wheat Genotypes.

The area of farming lands affected by increasing soil salinity is growing significantly worldwide. For this reason, breeding works are conducted to improve the salinity tolerance of important crop species. The goal of the present study was to indicate physiological or biochemical parameters characterizing three durum wheat accessions with various tolerance to salinity. The study was carried out on germinating seeds and mature plants of a Polish SMH87 line, an Australian cultivar 'Tamaroi' (salt-sensitive), and the BC5Nax2 line (salt-tolerant) exposed to 0-150 mM NaCl. Germination parameters, electrolyte leakage (EL), and salt susceptibility index were determined in the germinating caryopses, whereas photosynthetic parameters, carbohydrate and phenolic content, antioxidant activity as well as yield were measured in fully developed plants. The parameters that most differentiated the examined accessions in the germination phase were the percentage of germinating seeds (PGS) and germination vigor (Vi). In the fully developed plants, parameters included whether the plants had the maximum efficiency of the water-splitting reaction on the donor side of photosystem II (PSII)-Fv/F0, energy dissipation from PSII-DIo/CSm, and the content of photosynthetic pigments and hydrogen peroxide, which differentiated studied genotypes in terms of salinity tolerance degree. Salinity has a negative impact on grain yield by reducing the number of seeds per spike and the mass of one thousand seeds (MTS), which can be used as the most suitable parameter for determining tolerance to salinity stress. The most salt-tolerant BC5Nax2 line was characterized by the highest PGS, and Vi for NaCl concentration of 100-150 mM, content of chlorophyll a, b, carotenoids, and also MTS at all applied salt concentrations as compared with the other accessions. The most salt-sensitive cv. 'Tamaroi' demonstrated higher H2O2 concentration which proves considerable oxidative damage caused by salinity stress. Mentioned parameters can be helpful for breeders in the selection of genotypes the most resistant to this stress.

Glutamic Acid and Poly-γ-glutamic Acid Enhanced the Heat Resistance of Chinese Cabbage (Brassica rapa L. ssp. pekinensis) by Improving Carotenoid Biosynthesis, Photosynthesis, and ROS Signaling.

Heat stress is one of the most common agrometeorological risks in crop production in the middle and lower reaches of the Yangtze River in China. This study aimed to investigate whether glutamic acid (Glu) or poly-γ-glutamic acid (γ-PGA) biostimulants can improve the thermotolerance of a cool-season Chinese cabbage (Brassica rapa L. ssp. pekinensis) crop. Priming with Glu (2.0 mM) or γ-PGA (20 mg·L-1) was conducted at the third leaf stage by applying as daily foliar sprays for 5 days before 5 days of heat stress (45 °C in 16-h light/35 °C in 8-h dark). Coupled with morpho-physiological and biochemical analyses, transcriptomes of Glu or γ-PGA-primed Chinese cabbage under heat stress were examined by RNA-seq analysis. The results showed that the thermotolerance conferred by Glu and γ-PGA priming was associated with the increased parameters of vegetative growth, gas exchange, and chlorophyll fluorescence. Compared with the control, the dry weights of plants treated with Glu and γ-PGA increased by 51.52% and 39.39%, respectively. Glu and γ-PGA application also significantly increased the contents of total chlorophyll by 42.21% and 23.12%, and carotenoid by 32.00% and 24.00%, respectively. In addition, Glu- and γ-PGA-primed plants markedly inhibited the levels of malondialdehyde, electrolyte leakage, and super-oxide anion radical, which was accompanied by enhanced activity levels of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD). Enrichment analysis of Kyoto Encyclopedia of Genes and Genomes (KEGG) categories within the differentially expressed genes (DEGs) functional clusters of RNA-seq data indicated that the expression levels of the genes for DNA replication, DNA repair system, linoleic acid metabolism, cysteine and methionine metabolism, glutathione metabolism, purine and pyrimidine metabolism, carotenoid biosynthesis, and plant-pathogen interaction were commonly up-regulated by both Glu and γ-PGA priming. Glu treatment enhanced the expression levels of the genes involved in aliphatic glucosinolate and 2-oxocarboxylic acid, while γ-PGA treatment activated carotenoid cleavage reaction to synthesize abscisic acid. Taken together, both Glu and γ-PGA have great potential for the preadaptation of Chinese cabbage seedlings to heat stress, with Glu being more effective than γ-PGA.

Reaction of spring barley seedlings and H. incongruens crustaceans to the presence of acetylsalicylic acid in soil.

Acetylsalicylic acid (ASA) is one of the more commonly used analgesic, antipyretic, and anti-inflammatory as well as anticoagulant drugs available in the OTC (over the counter) segment. Due to the considerable use of this drug, an attempt was made to determine the effect of ASA on the crustacean Heterocypris incongruens and the monocotyledonous plant spring barley. The tested compounds were introduced into soil in which these organisms "lived". The study showed that ASA had an adverse effect on seed germination potential as well as a negative effect on spring barley growth; however, and photosynthetic pigments content was observed only at the highest concentrations of the studied compounds. ASA did not cause oxidative stress in plants but did also cause disturbances in the growth of H. incongruens, without causing their mortality. As a result, ASA may have certain negative effects on both crustaceans and monocots.

Gibberellic acid interacts with salt stress on germination, growth and polyamine gene expression in fennel (Foeniculum vulgare Mill.) seedlings.

This study aimed to rigorously investigate and integrate the underlying hypothesis that an enhancing effect of gibberellic acid (GA3, 3 µM) with increased growth actually leads to a modification of the physiological role of polyamines during salinity stress (NaCl, 100 mM) in fennel. These analyses concern both reserve tissues (cotyledons) and embryonic axes in growth. Physiological results indicate a restriction of germination, growth, mineral nutrition and damages to membranes of salt-treated seedlings. This was partially attenuated in seedlings treated with an interaction effect of GA3 and NaCl. Peroxidase and catalase activities showed a reduction or an augmentation according to the treatments and organs. The three main polyamines (PA): putrescine, spermidine and spermine were elevated in the salt-treated seedlings. Meanwhile, GA3 seed priming was extremely efficient in reducing PA levels in salt-stressed seedlings compared to the control. Response of PA genes to salinity was variable. Up-regulation was noted for SPMS1, ODC1, and ADC1 in hypocotyls and cotyledons (H + C) and down-regulation for SAMDC1 in the radicle. Interaction of salt/GA3 treatment showed different responses, only ODC1 in (H + C) and ADC1 in both radicle and (H + C) were overexpressed. Concerning other genes, no change in mRNA abundance was observed in both organs compared to the salt-treated seedlings. From these results, it could be inferred that the fennel seedlings were NaCl sensitive. This sensitivity was mitigated when GA3 applied for seed priming and applied in combination with NaCl, which resulted in a reduction of the PA content. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-022-01140-4.

Growth inhibition, toxin production and oxidative stress caused by three microplastics in Microcystis aeruginosa.

Microplastics (MPs) have aroused widespread concern due to their extensive distribution in aquatic environments and adverse effects on aquatic organisms. However, the underlying toxicity of different kinds of MPs on freshwater microalgae has not been examined in detail. In this study, we investigated the effects of polyvinyl chloride (PVC), polystyrene (PS) and polyethylene (PE) MPs on the growth of Microcystis aeruginosa, as well as on its toxin production and oxidative stress. We found that all three kinds of MPs had an obvious inhibition effect on the growth of M. aeruginosa. Considering the results of antioxidant-related indicators, the activity of superoxide dismutase (SOD) and catalase (CAT), and cell membrane integrity were greatly affected with exposure to PVC, PS and PE MPs. Moreover, the content of intracellular (intra-) and extracellular (extra-) microcystins (MCs) had a noticeable increase due to the presence of PVC, PS, and PE MPs. Finally, according to the comprehensive stress resistance indicators, the resistance of M. aeruginosa to three MPs followed the order: PE (3.701)> PS (3.607)> PVC (2.901). Our results provide insights into the effects of different kinds of MPs on freshwater algae and provide valuable data for risk assessment of different types of MPs.

A novel role of sulfate in promoting Mn phytoextraction efficiency and alleviating Mn stress in Polygonum lapathifolium Linn.

A hydroponic method was performed to explore the effects of sulfate supply on the growth, manganese (Mn) accumulation efficiency and Mn stress alleviation mechanisms of Polygonum lapathifolium Linn. Three Mn concentrations (1, 8 and 16 mmol L-1, representing low (Mn1), medium (Mn8) and high (Mn16) concentrations, respectively) were used. Three sulfate (S) levels (0, 200, and 400 µmol L-1, abbreviated as S0, S200 and S400, respectively) were applied for each Mn concentration. (1) The average biomass (g plant-1) of P. lapathifolium was ordered as Mn8 (6.36) > Mn1 (5.25) > Mn16 (4.16). Under Mn16 treatment, S addition increased (P < 0.05) biomass by 29.96% (S200) and 53.07% (S400) compared to that S0. The changes in the net photosynthetic rate and mean daily increase in biomass were generally consistent with the changes in biomass. (2) Mn accumulation efficiency (g plant-1) was ordered as Mn8 (99.66) > Mn16 (58.33) > Mn1 (27.38); and S addition increased (p < 0.05) plant Mn accumulation and Mn transport, especially under Mn16 treatment. (3) In general, antioxidant enzyme activities (AEAs) and malondialdehyde (MDA) in plant leaves were ordered in Mn16 > Mn8 > Mn1. Sulfate addition decreased (P < 0.05) AEAs and MDA under Mn16 treatment, while the changes were minor under Mn1 and Mn8 treatments. (4) Amino acid concentrations generally increased with increasing Mn concentration and S level. In summary, the medium Mn treatment promoted plant growth and Mn bioaccumulation; sulfate, especially at 400 µmol L-1 S, can effectively promote plant growth and Mn accumulation efficiency. The most suitable bioremediation strategy was Mn16 with 400 µmol L-1 S.

Application of boron reduces vanadium toxicity by altering the subcellular distribution of vanadium, enhancing boron uptake and enhancing the antioxidant defense system of watermelon.

Vanadium (V) is the fifth most abundant transition metal, elevated levels of V are hazardous to plants. Boron (B) is an essential micronutrient for plants and can mitigate heavy metal toxicity. However, the mechanism used by B to promote tolerance to vanadium is unknown. In this study, a combination of physiological and gene expression analysis was used to explain mechanism of B (75 µM) induced V (40 mg L-1) stress tolerance in watermelon. V stress severely reduced root and shoot growth and increased the accumulation of ROS. B application improved tolerance to V by enhancing the expression of B transporter genes (ClaNIP5;1-1, ClaNIP5;1-2, ClaBOR4) that facilitated B uptake and transport while restricting V transport in plant tissues. At cellular level, the higher V retention in leaves was achieved by cell wall chelation, whereas, the higher V exclusion in vacuole of root cell was driven by elevated vacuolar H+-ATPase, H+-PPase activities, and transcript level of ClaVHP1;1, ClaPDR12-1 and ClaPDR12-2 genes facilitated by B application. Moreover, B application reduced tissue ROS cascade by enhancing antioxidant enzymatic activity and expression of superoxide dismutase (ClaCSD1-1, ClaCSD1-2, ClaCSD3, ClaMSD1) and catalase (ClaCAT2-1, ClaCAT2-2) genes that enhanced the defense mechanism of the V treated plants, improved root and shoot growth and tolerance index of watermelon. In conclusion, we demonstrate that ameliorative effect of B in tolerance to V of watermelon was based on B homeostasis and improved antioxidant defense system. These findings might help to increase watermelon production in V polluted soils.

Glycosyltransferase OsUGT90A1 helps protect the plasma membrane during chilling stress in rice.

Due to its subtropical origins, rice (Oryza sativa) is sensitive to low-temperature stress. In this study, we identify LOC_Os04g24110, annotated to encode the UDP-glycosyltransferase enzyme UGT90A1, as a gene associated with the low-temperature seedling survivability (LTSS) quantitative trait locus qLTSS4-1. Differences between haplotypes in the control region of OsUGT90A1 correlate with chilling tolerance phenotypes, and reflect differential expression between tolerant and sensitive accessions rather than differences in protein sequences. Expression of OsUGT90A1 is initially enhanced by low temperature, and its overexpression helps to maintain membrane integrity during cold stress and promotes leaf growth during stress recovery, which are correlated with reduced levels of reactive oxygen species due to increased activities of antioxidant enzymes. In addition, overexpression of OsUGT90A1 in Arabidopsis improves freezing survival and tolerance to salt stress, again correlated with enhanced activities of antioxidant enzymes. Overexpression of OsUGT90A1 in rice decreases root lengths in 3-week-old seedlings while gene-knockout increases the length, indicating that its differential expression may affect phytohormone activities. We conclude that higher OsUGT90A1 expression in chilling-tolerant accessions helps to maintain cell membrane integrity as an abiotic stress-tolerance mechanism that prepares plants for the resumption of growth and development during subsequent stress recovery.

Growth performance, phenotypic traits, and antioxidant responses of the rotifer Brachionus plicatilis under different proportions of Phaeocystis globosa.

Harmful Phaeocystis blooms disrupt seawater recreation and pose serious challenges to aquatic animals. The growth performance, phenotypic traits, and antioxidant responses of Brachionus plicatilis Müller to different proportions of Phaeocystis globosa were evaluated. B. plicatilis rotifers were exposed to cultures with Chlorella sp. and P. globosa alone and in mixtures of these two algae with proportions of 25%, 50%, and 75%. The total proportions of the two algae were maintained at 100%. Results showed that P. globosa inhibited the rotifer net reproduction rate, intrinsic growth rate, and finite rate of increase (P < 0.01). It induced the formation of defense phenotypic traits in terms of the increased posterolateral spine length and the reduced body length, swimming speed, and grazing rate of B. plicatilis (P < 0.001). Superoxide dismutase and catalase activities decreased, but the reactive oxygen species levels increased as the proportions of P. globosa increased (P < 0.01). The mixture of 50% Chlorella and 50% Phaeocystis positively affected the glutathione content, glutathione peroxidase activity, and generation time of rotifers (P < 0.01). Although P. globosa released toxicants with harmful effects on the growth performance of B. plicatilis, rotifers changed their antioxidant defense system and formed defense phenotypic traits in response to eutrophic conditions.

Methyl Jasmonate Induced Oxidative Stress and Accumulation of Secondary Metabolites in Plant Cell and Organ Cultures.

Recently, plant secondary metabolites are considered as important sources of pharmaceuticals, food additives, flavours, cosmetics, and other industrial products. The accumulation of secondary metabolites in plant cell and organ cultures often occurs when cultures are subjected to varied kinds of stresses including elicitors or signal molecules. Application of exogenous jasmonic acid (JA) and methyl jasmonate (MJ) is responsible for the induction of reactive oxygen species (ROS) and subsequent defence mechanisms in cultured cells and organs. It is also responsible for the induction of signal transduction, the expression of many defence genes followed by the accumulation of secondary metabolites. In this review, the application of exogenous MJ elicitation strategies on the induction of defence mechanism and secondary metabolite accumulation in cell and organ cultures is introduced and discussed. The information presented here is useful for efficient large-scale production of plant secondary metabolites by the plant cell and organ cultures.

Compensation of Mutation in Arabidopsis glutathione transferase (AtGSTU) Genes under Control or Salt Stress Conditions.

Glutathione transferases (GSTs) play a crucial role in detoxification processes due to the fact of their glutathione (GSH) conjugating activity, and through glutathione peroxidase or dehydroascorbate reductase (DHAR) activities, they influence the redox state of GSH and ascorbate (AsA). The plant-specific tau (GSTU) group is the largest class of Arabidopsis GSTs, and their members are involved in responses to different abiotic stresses. We investigated the effect of salt stress on two-week-old Arabidopsis thaliana wild-type (Col-0), Atgstu19 and Atgstu24 mutant plants after applying 150 mM NaCl for two days. The Atgstu19 seedlings had lower GST activity and vitality both under control conditions and after salt stress than the wild-type, but the level of total ROS was similar to the Col-0 plants. The GST activity of the knockout Atgstu24 mutant was even higher under control conditions compared to the Col-0 plants, while the ROS level and its vitality did not differ significantly from the wild-type. Analysis of the AtGSTU expression pattern revealed that the mutation in a single AtGSTU gene was accompanied by the up- and downregulation of several other AtGSTUs. Moreover, elevated AsA and GSH levels, an altered GSH redox potential and increased DHAR and glutathione reductase activities could help to compensate for the mutation of AtGSTU genes. The observed changes in the mutants suggest that the investigated isoenzymes influence the redox homeostasis under control conditions and after NaCl treatment in Arabidopsis seedlings. These data indicate for the first time the more general role of a temporary shift of redox status as part of GST mechanisms and regulation.