Toxicity of methylparaben and its chlorinated derivatives to Allium cepa L. and Eisenia fetida Sav.

Methylparaben, chloro-methylparaben, and dichloro-methylparaben were evaluated in Allium cepa at 5, 10, 50, and 100 µg/L and in Eisenia fetida at 10 and 100 µg/L. In A. cepa roots, 100 µg/L methylparaben and 50 and 100 µg/L chlorinated methylparabens reduced cell proliferation, caused cellular changes, and reduced cell viability in meristems, which caused a reduction in root growth. Furthermore, they caused drastic inhibition of catalase, ascorbate peroxidase, and superoxide dismutase; activated guaiacol peroxidase and promoted lipid peroxidation in meristematic root cells. In earthworms, after 14 days exposure to the three compounds, there were no deaths, and catalase, ascorbate peroxidase, and superoxide dismutase were not inhibited. However, guaiacol peroxidase activity and lipid peroxidation were observed in animals exposed to dichloro-methylparaben. Soils with dichloro-methylparaben also caused the escape of earthworms. It is inferred that the recurrent contamination of soils with these methylparabens, with emphasis on chlorinated derivatives, can negatively impact different species that depend directly or indirectly on soil to survive.

Co-exposure of sulfur nanoparticles and Cu alleviate Cu stress and toxicity to oilseed rape Brassica napus L.

Experiments were performed to explore the impact of sulfur nanoparticles (SNPs) on growth, Cu accumulation, and physiological and biochemical responses of oilseed rape (Brassica napus L.) inoculated with 5 mg/L Cu-amended MS medium supplemented with or without 300 mg/L SNPs exposure. Cu exerted severe phytotoxicity and inhibited plant growth. SNPs application enhanced the shoot height, root length, and dry weight of shoot and root by 34.6%, 282%, 41.7% and 37.1%, respectively, over Cu treatment alone, while the shoot and root Cu contents and Cu-induced lipid perodixation as the malondialdehyde (MDA) levels in shoots and roots were decreased by 37.6%, 35%, 28.4% and 26.8%. Further, the increases in superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR) and glutathione S-transferase (GST) enzyme activities caused by Cu stress were mitigated in shoots (10.9%-37.1%) and roots (14.6%-35.3%) with SNPs addition. SNPs also positively counteracted the negative effects on shoot K, Ca, P, Mg, Mn, Zn and Fe contents and root K, Ca, Mg and Mn contents from Cu exposure alone, and significantly promoted the nutrients accumulation in plant. Additionally, in comparison with common bulk sulfur particles (BSPs) and sulfate, SNPs showed more positive effects on promoting growth in shoots (6.7% and 19.5%) and roots (10.9% and 15.1%), as well as lowering the shoot Cu content (40.1% and 43.3%) under Cu stress. Thus, SNPs application has potential to be a green and sustainable technology for increasing plant productivity and reducing accumulation of toxic metals in heavy metal polluted soils.

Effects of exogenous taurine on growth, photosynthesis, oxidative stress, antioxidant enzymes and nutrient accumulation by Trifolium alexandrinum plants under manganese stress.

Plants essentially require manganese (Mn) for their normal metabolic functioning. However, excess Mn in the cellular environment is detrimental to plant growth, development, and physio-biochemical functions. Taurine (TAU) is an amino acid with potent antioxidant and anti-inflammatory properties in animals and humans. However, no previous study has investigated the potential of TAU in plant metal stress tolerance. The current study provides some novel insights into the effect of TAU in modulating the defense system of Trifolium alexandrinum plants under Mn toxicity. Manganese toxicity resulted in higher oxidative stress and membrane damage through increased superoxide radical, hydrogen peroxide, malondialdehyde, and methylglyoxal generation alongside enhanced lipoxygenase (LOX) activity. Mn toxicity also resulted in limited uptake of potassium (K+), phosphorus (P), calcium (Ca2+), and increased the accumulation of Mn in both leaf and roots. However, TAU circumvented the Mn-induced oxidative stress by upregulating the activities of antioxidant enzymes (ascorbate peroxidase, peroxidase, catalase, glutathione reductase, glutathione-S-transferase, and superoxide dismutase) and levels of ascorbic acid, proline, anthocyanins, phenolics, flavonoids and glutathione (GSH). Taurine conspicuously improved the growth, photosynthetic pigments, hydrogen sulphide (H2S), and nitric oxide (NO) levels of Mn stressed plants. Taurine also improved the uptake of K+, Ca2+, P and reduced the Mn content in stressed plants. Overall, exogenous taurine might be a suitable strategy to combat Mn stress in T. alexandrinum plants but applications at field levels for various crops and metal toxicities and economic suitability need to be addressed before final recommendations.

Impact of repeated freeze-thaw cycles environment on the allelopathic effect to Secale cereale L. seedlings.

Allelopathy, as environmental stress, plays a prominent role in stress ecotoxicity, and global warming directly increases freeze-thaw cycles (FTCs) frequency in the winter. Yet, the effect between FTCs environment and allelopathy stress is rarely known, and the interaction of allelopathy stresses lacks consideration. Here, we addressed interactions between artemisinin stress (AS) and A. trifida extract stress (AES) under Non-FTCs and FTCs environments. The results found that AS and AES had an antagonistic relation under Non-FTCs environment, while a strong synergism and cooperation under FTCs environment affect the growth and physiology in S. cereale seedlings. Besides, AS and AES under FTCs environment had more inhibition on the growth of roots and shoots, chlorophylls, photosynthetic parameters, and relative water content; while more promotion on malondialdehyde, soluble sugar, and soluble protein. Moreover, the antioxidant enzyme activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) were increased by AS and AES, showing a good resistance of S. cereale seedlings to allelopathy stress, but FTCs environment significantly weakened this resistance. Thus, the allelopathic effect of AS and AES on S. cereale seedlings was significantly emphasized by FTCs environment.

A Validated Set of Ascorbate Peroxidase-Based Organelle Markers for Electron Microscopy of Saccharomyces cerevisiae.

Genetically encoded tags, such as engineered ascorbate peroxidase APEX2, offer unique advantages for the specific labeling of subcellular structures in electron microscopy (EM). However, the use of APEX2 in EM investigation of yeast has been limited. Here we describe the development of APEX2-based organelle markers for Saccharomyces cerevisiae. We found that with regard to APEX2 -catalyzed formation of diaminobenzidine precipitation, cell wall removal was not essential during sample preparation, yet the presence of fluorescent proteins in APEX2 chimeras had a negative impact. We showed that major organelles including endoplasmic reticulum, early Golgi, late Golgi/early endosomes, late endosomes, mitochondria, peroxisomes, and lipid droplets could be labeled by appropriate APEX2 chimeras. The subcellular localization of our APEX2 chimeras was verified by EM visualization and supplemented with immunofluorescence colocalization analysis when necessary, validating their feasibility as organelle markers. IMPORTANCE Yeast is an excellent single cellular model system for studying basic cellular processes. However, yeast cells are much smaller than most animal and plant cells, making the observation and recognition of yeast subcellular structures challenging. Here we developed a set of yeast organelle markers for use in electron microscopy and documented our technical approach for using this method.

CfAPX, a cytosolic ascorbate peroxidase gene from Cryptomeria fortunei, confers tolerance to abiotic stress in transgenic Arabidopsis.

Plants subjected to biotic or abiotic stresses produce a large amount of reactive oxygen species (ROS). If ROS cannot be cleared in time, they cause a series of harmful reactions in plants. Ascorbate peroxidase (APX) is a key enzyme that removes ROS from plant cells and plays a vital role in plant stress resistance. However, to date, no studies on APX homologs in Cryptomeria fortunei have been reported. In this study, we isolated complementary DNA (cDNA) encoding APXfrom C. fortunei needles, which is referred to as CfAPX, by rapid amplification of cDNA ends (RACE). The full-length CfAPX sequence was 1226 bp in length and included a 750-bp open reading frame (ORF) encoding a protein of 249 amino acids. Phylogenetic analysis showed that APXs of different plant species have been highly evolutionarily conserved. CfAPX was shown to belong to the cytoplasmic subgroup and was more closely related to GbAPX of the gymnosperm Ginkgo biloba. CfAPX showed no transcriptional activity in yeast cells but was highly expressed in cones. To better handle abiotic stresses, compared with wild-type (WT) Arabidopsis thaliana, 35S::CfAPX transgenic Arabidopsis strongly expressed CfAPX, presented increased antioxidant enzyme activities, ascorbic acid (AsA) contents, chlorophyll levels and fluorescence parameter and reduced malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents. In addition, CfAPX expression in C. fortunei was mostly upregulated under stress. In summary, CfAPX confers abiotic stress responses to plants, which provides a scientific basis for subsequent breeding for increased stress resistance in C. fortunei.

Integration of signals from different cortical areas in higher order thalamic neurons.

Higher order thalamic neurons receive driving inputs from cortical layer 5 and project back to the cortex, reflecting a transthalamic route for corticocortical communication. To determine whether or not individual neurons integrate signals from different cortical populations, we combined electron microscopy "connectomics" in mice with genetic labeling to disambiguate layer 5 synapses from somatosensory and motor cortices to the higher order thalamic posterior medial nucleus. A significant convergence of these inputs was found on 19 of 33 reconstructed thalamic cells, and as a population, the layer 5 synapses were larger and located more proximally on dendrites than were unlabeled synapses. Thus, many or most of these thalamic neurons do not simply relay afferent information but instead integrate signals as disparate in this case as those emanating from sensory and motor cortices. These findings add further depth and complexity to the role of the higher order thalamus in overall cortical functioning.

The effect of NADPH oxidase inhibitor diphenyleneiodonium (DPI) and glutathione (GSH) on Isatis cappadocica, under Arsenic (As) toxicity.

The present work was conducted to assess the effects of arsenic (As, 1000 µM), diphenyleneiodonium (DPI, 10 µM) and reduced glutathione (GSH, 500 µM) on Isatis cappadocica. As treatment decreased plant growth and fresh and dry weight of shoot and root and also enhanced the accumulation of As. As stress also enhanced the oxidative stress biomarkers, hydrogen peroxide (H2O2) and malondialdehyde (MDA) content. However, the application of GSH decreased the content of H2O2 and MDA by 43% and 55%, respectively, as compared to As treatment. The antioxidants like superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), glutathione reductase (GR) and glutathione S-transferase (GST) also enhanced with As stress. NADPH oxidase inhibitor, the DPI, enhances the effect of As toxicity by increasing the accumulation of As, H2O2, MDA. DPI also enhances the activity of antioxidant enzymes except GR and GST, However, the application GSH increased the plant growth and biomass yield, decreases accumulation of As, H2O2 and MDA content in As as well as As + DPI treated plants. The thiols content [total thiol (TT), non-protein thiol (NPT) protein thiols (PT), and glutathione (GSH)] were decreased in the As + DPI treatment but supplementation of GSH enhanced them. Novelty statement: The study reveals the beneficial role of GSH in mitigating the deleterious effects of Arsenic toxicity through its active involvement in the antioxidant metabolism, thiol synthesis and osmolyte accumulation. Apart from As, We provided the plants NADPH oxidase inhibitor, the diphenyleneiodonium (DPI), which boosts the As toxicity. At present, there is dearth of information pertaining to the effects of DPI on plants growth and their responses under heavy metal stress.GSH application reversed the effect of diphenyleneiodonium (DPI) under As stress preventing the oxidative damage to biomolecules through the modulation of different antioxidant enzymes. The application of GSH for As stressed soil could be a sustainable approach for crop production.

Selenium biofortification enhances ROS scavenge system increasing yield of coffee plants.

There are conclusive evidences of selenium (Se) deficiency in Brazilian soils and foods. Brazil is the largest producer and consumer of coffee worldwide, which favors agronomic biofortification of its coffee. This study aimed to evaluate effects of foliar application of three formulations and six rates of Se on antioxidant metabolism, agronomic biofortification and yield of coffee beans. Seven Se concentrations (0, 10, 20, 40, 80, 100 and 160 mg L-1) were applied from three formulations of Se (sodium selenate, nano-Se 1500, and nano-Se 5000). Selenium application up to 40 mg L-1 increased the concentration of photosynthetic pigments such as chlorophylls, pheophytins and carotenoids in coffee leaves. Foliar application of Se ranging from 20 to 80 mg L-1 decreased lipid peroxidation and concentration of hydrogen peroxide, but increased superoxide dismutase, ascorbate peroxidase, catalase and glutathione reductase activities in coffee leaves. These results indicated that foliar Se application stimulates antioxidative metabolism to mitigate reactive oxygen species. Foliar application of 20 mg Se L-1 of sodium selenate increased coffee yield by 38%, and 160 mg Se L-1 of nano-Se 5000 increased dramatically coffee yield by 42%. Selenium concentration in grains ranged from 0.116 to 4.47 mg kg-1 (sodium selenate), 4.84 mg kg-1 (nano-Se 1500) and 5.82 mg kg-1 (nano-Se 5000). The results suggest the beneficial effect of Se on the increment of photosynthetic pigments, antioxidative metabolism, increased coffee yield and nutritional quality of grains. The recommended foliar Se application in this study can mitigate abiotic stressors such as high temperatures resulting in higher yield of coffee plants.

Hydrogen peroxide modulates activity and expression of antioxidant enzymes and protects photosynthetic activity from arsenic damage in rice (Oryza sativa L.).

We studied the role of H2O2 in the protection of photosynthesis from arsenic (As) damage in rice (Oryza sativa L.) by examining the antioxidant system, photosynthesis, and growth attributes. Among the As concentrations (0, 20, 30, 40 and 50 µM) tested, maximum oxidative stress and inhibition in photosynthesis and growth were found with 50 µM As. The application of 50 µM H2O2 resulted in alleviation of the adverse effects of 50 µM As on Pigment System (PS) II activity, photosynthesis, and growth. Hydrogen peroxide supplementation induced the activity of superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) and increased reduced glutathione (GSH) content and proline metabolism. The expression of SOD and APX, PSBA and PSBB was induced in the presence of H2O2 to alleviate the As damage to PS II and maintain photosynthetic activity. The role of H2O2 as a signaling molecule is shown in the protection of photosynthetic activity in rice from As toxicity through regulation on the activity and the expression of antioxidant enzymes.

Enteromorpha compressa extract induces anticancer activity through apoptosis and autophagy in oral cancer.

Marine algae are an auspicious source of innovative bioactive compounds containing possible therapeutic agents against mammalian cancers. However, the mechanism by which bioactive algal compounds exhibit anticancer activity against oral squamous cell carcinoma (OSCC) is scant. The main objective of the current study was to explore the properties of the Enteromorpha compressa solvent extracts that induced autophagy and apoptosis with reference to their potent phytochemical and antioxidant properties. The presence of bioactive compounds were confirmed by UV and FT-IR spectroscopy. The free radical scavenging activity were analyzed by evaluating H2O2, DPPH, superoxide and hydroxyl activity. The anticancer activities of the extracts were investigated by employing clonogenic and scratch assay. The apoptosis potential was evaluated by DAPI and MMP by Rh123 fluorescence assay. Moreover, the CAT, SOD, GPX, APX, and GR activities were measured. The autophagy potential was evaluated by LC3 puncta formation, acridine orange in addition to LysoTracker staining. The present investigation revealed that the methanolic extract of E. compressa elicited robust free radical scavenging activity that discerns its antiproliferative potency. Moreover, the methanolic algal extract boosted intrinsic apoptosis against OSCC by downregulating protective antioxidant enzymes. Furthermore, it also revealed induction of autophagy to promote cell death in oral cancer cells. The presence of novel bioactive compounds in E. compressa has uncovered possible therapeutic value against OSCC by modulating antioxidant defense system, apoptosis and autophagy that could be used to explore very competent algal candidates for the development of potential alternative anticancer drugs.

The ameliorative effects of exogenous inoculation of Piriformospora indica on molecular, biochemical and physiological parameters of Artemisia annua L. under arsenic stress condition.

Aim of the current study was to investigate the effect of exogenously inoculated root endophytic fungus, Piriformospora indica, on molecular, biochemical, morphological and physiological parameters of Artemisia annua L. treated with different concentrations (0, 50, 100 and 150 µmol/L) of arsenic (As) stress. As was significantly accumulated in the roots than shoots of P. indica-inoculated plants. As accumulation and immobilization in the roots is directly associated with the successful fungal colonization that restricts most of As as compared to the aerial parts. A total of 4.1, 11.2 and 25.6 mg/kg dry weight of As was accumulated in the roots of inoculated plants supplemented with 50, 100 and 150 µmol/L of As, respectively as shown by atomic absorption spectroscopy. P. indica showed significant tolerance in vitro to As toxicity even at high concentration. Furthermore, flavonoids, artemisinin and overall biomass were significantly increased in inoculated-stressed plants. Superoxide dismutase and peroxidase activities were increased 1.6 and 1.2 fold, respectively under 150 µmol/L stress in P. indica-colonized plants. Similar trend was followed by ascorbate peroxidase, catalase and glutathione reductase. Like that, phenolic acid and phenolic compounds showed a significant increase in colonized plants as compared to their respective control/un-colonize stressed plants. The real-time PCR revealed that transcriptional levels of artemisinin biosynthesis genes, isoprenoids, terpenes, flavonoids biosynthetic pathway genes and signal molecules were prominently enhanced in inoculated stressed plants than un-inoculated stressed plants.

Selenium toxicity stress-induced phenotypical, biochemical and physiological responses in rice plants: Characterization of symptoms and plant metabolic adjustment.

Selenium (Se) at low concentration is considered benefit element to plants. The range between optimal and toxic concentration of Se is narrow and varies among plant species. This study aimed to evaluate the phenotypic, physiological and biochemical responses of four rice genotypes (BRS Esmeralda, BRSMG Relâmpago, BRS Bonança and Bico Ganga) grown hydroponically treated with sodium selenate (1.5 mM L-1). Selenium treated plants showed a dramatically decrease of soluble proteins, chlorophylls, and carotenoids concentration, resulting in the visual symptoms of toxicity characterized as leaf chlorosis and necrosis. Selenium toxicity caused a decrease on shoot and root dry weight of rice plants. Excess Se increased the oxidative stress monitored by the levels of hydrogen peroxide and lipid peroxidation. The enzymatic antioxidant system (catalase, superoxide dismutase, and ascorbate peroxidase) increased in response to Se supply. Interestingly, primary metabolism compounds such as sucrose, total sugars, nitrate, ammonia and amino acids increased in Se-treated plants. The increase in these metabolites may indicate a defense mechanism for the osmotic readjustment of rice plants to mitigate the toxicity caused by Se. However, these metabolites were not effective to minimize the damages on phenotypic traits such as leaf chlorosis and reduced shoot and root dry weight in response to excess Se. Increased sugars profile combined with antioxidant enzymes activities can be an effective biomarkers to indicate stress induced by Se in rice plants. This study shows the physiological attributes that must be taken into account for success in the sustainable cultivation of rice in environments containing excess Se.

Selenate and selenite affect photosynthetic pigments and ROS scavenging through distinct mechanisms in cowpea (Vigna unguiculata (L.) walp) plants.

Selenium (Se) is a beneficial element to higher plants. Application of Se at low concentrations enhances the antioxidant metabolism reducing the reactive oxygen species (ROS) generated by plant membrane cells. This study aimed to evaluate how the application of Se in the forms sodium selenate and sodium selenite regulates ROS scavenging in field-grown cowpea plants. Seven Se application rates (0; 2.5; 5; 10; 20; 40 and 60 g ha-1) of each of the two Se forms were applied to plants via the soil. Photosynthetic pigments concentration, gas exchange parameters, lipid peroxidation by malondialdehyde (MDA) concentration, hydrogen peroxide concentration, activity of catalase (CAT, EC:1.11.1.6), glutathione reductase (GR, EC:1.6.4.2), ascorbate peroxidase (APX, EC:1.11.1.11) and Se concentration in leaves and grains were evaluated. In general, Se application led to a decrease in chlorophyll a concentration whilst leading to an increase in chlorophyll b, indicating conservation of total chlorophyll concentration. Application of 2.5 g ha-1 of Se as selenate provided a notable increase in total chlorophyll and total carotenoids compared to the other application rates. Selenate and selenite application decreased lipid peroxidation. However, each Se source acted in a different pathway to combat ROS. While selenate showed more potential to increase activity of APX and GR, selenite showed a higher potential to increase CAT activity. The negative correlation between CAT and GR is indicative that both pathways might be activated under distinct circumstances. The more prominent activity of CAT under high rates of selenite resulted in a negative correlation of this enzyme with chlorophyll a and carotenoids. Both selenate and selenite application increased sucrose and total sugars concentration in leaves of cowpea plants. Overall, these results indicate that application of Se in cowpea under field conditions stimulates distinct pathways to scavenge ROS. This could prove beneficial to mitigate oxidative stress during plant development.

Cytosolic ascorbate peroxidase 1 modulates ascorbic acid metabolism through cooperating with nitrogen regulatory protein P-II in tea plant under nitrogen deficiency stress.

Nitrogen (N) element is essential nutrient, and affect metabolism of secondary metabolites in higher plants. Ascorbate peroxidase (APX) plays an important role in ascorbic acid (AsA) metabolism of tea plant. However, the roles of cytosolic ascorbate peroxidase 1 (CsAPX1) in AsA metabolism under N deficiency stress in tea plant remains unclear in detail. In this work, nitrogen regulatory protein P-II (CsGLB1) and CsAPX1 were identified by isobaric tags for relative and absolute quantitation (iTRAQ) from tea plant. The cell growth rates in transgenic Escherichia coli overexpressing CsAPX1 and CsGLB1 were higher than empty vector under N sufficiency condition. Phenotype of shoots and roots, AsA accumulation, and expression levels of AtAPX1 and AtGLB1 genes were changed in transgenic Arabidopsis hosting CsAPX1 under N deficiency stress. These findings suggested that cytosolic CsAPX1 acted a regulator in AsA accumulation through cooperating with GLB1 under N deficiency stress in tea plant.

The ascorbate peroxidase 1 regulates ascorbic acid metabolism in fresh-cut leaves of tea plant during postharvest storage under light/dark conditions.

Postharvest storage conditions affect the ascorbic acid (AsA) levels in fresh-cut leaves of horticultural crops. However, the detailed mechanism of AsA metabolism in the fresh-cut leaves of tea plant (Camellia sinensis) during postharvest storage under light/dark conditions remains unclear. To investigate the AsA mechanism, we treated fresh-cut tea leaves with light/dark during postharvest storage. An ascorbate peroxidase 1 (CsAPX1) protein involved in AsA metabolism was identified by iTRAQ analysis. Gene expression profile of CsAPX1 encoding ascorbate peroxidase (APX) was regulated by light/dark conditions. AsA accumulation and APX activity were suppressed by light/dark conditions. SDS-PAGE analysis showed that the molecular mass of recombinant CsAPX1 protein was about 34.45 kDa. Subcellular localization indicated that CsAPX1 protein was a cytosol ascorbate peroxidase. Overexpression CsAPX1 in Arabidopsis indicated that the decrease of AsA content and APX activity in transgenic lines were less significant than that of WT during postharvest storage under light/dark conditions. These data suggested that CsAPX1 involved in regulating AsA metabolism through effecting on the changes of AsA accumulation and APX activity in fresh-cut tea leaves during postharvest storage under light/dark conditions.

Phosphorus toxicity disrupts Rubisco activation and reactive oxygen species defence systems by phytic acid accumulation in leaves.

Phosphorus (P) is an essential mineral nutrient for plants. Nevertheless, excessive P accumulation in leaf mesophyll cells causes necrotic symptoms in land plants; this phenomenon is termed P toxicity. However, the detailed mechanisms underlying P toxicity in plants have not yet been elucidated. This study aimed to investigate the molecular mechanism of P toxicity in rice. We found that under excessive inorganic P (Pi) application, Rubisco activation decreased and photosynthesis was inhibited, leading to lipid peroxidation. Although the defence systems against reactive oxygen species accumulation were activated under excessive Pi application conditions, the Cu/Zn-type superoxide dismutase activities were inhibited. A metabolic analysis revealed that excessive Pi application led to an increase in the cytosolic sugar phosphate concentration and the activation of phytic acid synthesis. These conditions induced mRNA expression of genes that are activated under metal-deficient conditions, although metals did accumulate. These results suggest that P toxicity is triggered by the attenuation of both photosynthesis and metal availability within cells mediated by phytic acid accumulation. Here, we discuss the whole phenomenon of P toxicity, beginning from the accumulation of Pi within cells to death in land plants.

Phytochemical, antioxidant, enzyme activity and antifungal properties of Satureja khuzistanica in vitro and in vivo explants stimulated by some chemical elicitors.

Context: Satureja khuzistanica Jamzad. (Lamiaceae), is known for its antifungal and antioxidant compounds, especially rosmarinic acid (RA).Objective: The study examines the effect of elicitors on RA production and phytochemical properties of S. khuzistanica.Materials and methods: In vitro plants were treated with methyl jasmonate (MeJA) and multi-walled carbon nanotubes (MWCNTs). In vivo plants were treated with MWCNTs and salicylic acid (SA). RA was measured by HPLC. Catalase (CAT), guaiacol peroxidase (POD) and ascorbate peroxidase (APX) were quantified. DPPH and ß-carotene were assayed in in vivo extracts. The antifungal effects of extracts were evaluated against Fusarium solani K (FsK).Results: The highest RA contents of in vitro plants were 50 mg/L MeJA (140.99 mg/g DW) and 250 mg/L MWCNTs (140.49 mg/g DW). The highest in vivo were 24 h MWCNTs (7.13 mg/g DW) and 72 h SA (9.12 mg/g DW). The maximum POD and APX activities were at 100 mg/L MeJA (5 and 4 mg protein, respectively). CAT had the highest activities at 50 mg/L MeJA (2 mg protein). DPPH and ß-carotene showed 50% and 80% inhibition, respectively. The FsK aggregation was the lowest for in vitro extract in number of conidia [1.82 × 1010], fresh weight (6.51 g) and dry weight (0.21 g) that proved RA inhibitory effects. The callus reduces FsK growth diameter to 2.75 on the 5th day.Discussion and conclusions: Application of MeJA, SA, and MWCNTSs could increase RA in S. khuzistanica and highlighted potential characteristics in pharmaceutical and antifungal effects.

Reactive oxygen species scavenging mechanisms associated with polyethylene glycol mediated osmotic stress tolerance in Chinese potato.

Influence of polyethylene glycol (PEG) mediated osmotic stress on reactive oxygen species (ROS) scavenging machinery of Chinese potato (Solenostemon rotundifolius (Poir.) J. K. Morton) was investigated. Five genotypes of Chinese potato were raised in Murashige and Skoog (MS) basal medium containing 6-benzylaminopurine (BAP, 1 mg L-1) along with various concentrations of PEG-6000 mediated stress conditions (0, -0.2 and -0.5 MPa) and evaluated for osmotic stress tolerance in vitro. The medium containing PEG-6000 had a detrimental effect on plantlet growth and development while compared with the control. Accumulation of H2O2 was lower in Sreedhara and Subala and higher in Nidhi under PEG stress, which was evident by in situ detection in leaves. Lipid peroxidation product such as malondialdehyde (MDA) content was increased due to PEG stress which was more in susceptible genotype than that in tolerant ones. An enhanced ROS-scavenging antioxidant enzyme was observed under stress with respect to the control. The enzymes of ascorbate-glutathione cycle showed an important role in scavenging ROS. The imposition of PEG stress also increased the non-enzymatic antioxidants viz., the ascorbate and reduced glutathione content which was prominent in tolerant genotypes in comparison to susceptible. The present study indicated that, Sreedhara and Subala showed more tolerance to osmotic stress with better ROS scavenging machineries which would be the lines of interest for augmenting future breeding strategies in this climate resilient minor tuber crop.

Toxic levels of manganese in an acidic Cambisol alters antioxidant enzymes activity, element uptake and subcellular distribution in Triticum aestivum.

In the Montado system, in Portuguese Alentejo region, some Eutric Cambisols are known to promote manganese (Mn) toxicity in wheat. Variation on bioavailable Mn concentration depends on soil acidity, which can be increased by natural events (e.g. waterlogging) or human activity (e.g. excess use of chemical fertilizers). The effect of increasing soil Mn on crop element uptake, element distribution and oxidative stress was evaluated on winter wheat (Triticum aestivum). Plants were grown for 3 weeks in an acidic Cambisol spiked with increasing Mn concentrations (0, 45.2 and 90.4 mg MnCl2/Kg soil). Calcium (Ca), phosphorus (P), magnesium (Mg) and Mn were quantified in the soil solution, root and shoot tissues and respective subcellular fractions. The activity of the antioxidant enzymes ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), guaiacol peroxidase (GPX) and superoxide dismutase (SOD) were determined in extracts of wheat shoots and roots. Overall, increase in soil bioavailable Mn inhibited the uptake of other elements, increased the Ca proportion in the root apoplast, promoted the translocation of Mn and P to shoot tissues and increased their proportion in the shoot vacuoles. Wheat roots showed greater antioxidant enzymes activities than shoots. These activities decreased at the highest soil Mn concentration in both plant parts. Wheat roots appear to be more sensitive to oxidative stress derived from excess soil Mn and promote Mn translocation and storage in shoot vacuoles, probably in Mn and P complexes, as a detoxification strategy. Improvement in wheat production, in acidic soils, may rely on the enhancement of its Mn detoxification strategies.