Lipid Peroxidation In Plants Research Articles

Alginate–Bentonite Encapsulation of Extremophillic Bacterial Consortia Enhances Chenopodium quinoa Tolerance to Metal Stress

This study explores the encapsulation in alginate/bentonite beads of two metal(loid)-resistant bacterial consortia (consortium A: Pseudomonas sp. and Bacillus sp.; consortium B: Pseudomonas sp. and Bacillus sp.) from the Atacama Desert (northern Chile) and Antarctica, and their influence on physiological traits of Chenopodium quinoa growing in metal(loid)-contaminated soils. The metal(loid) sorption capacity of the consortia was determined. Bacteria were encapsulated using ionic gelation and were inoculated in soil of C. quinoa. The morphological variables, photosynthetic pigments, and lipid peroxidation in plants were evaluated. Consortium A showed a significantly higher biosorption capacity than consortium B, especially for As and Cu. The highest viability of consortia was achieved with matrices A1 (3% alginate and 2% bentonite) and A3 (3% alginate, 2% bentonite and 2.5% LB medium) at a drying temperature of 25 °C and storage at 4 °C. After 12 months, the highest viability was detected using matrix A1 with a concentration of 106 CFU g−1. Further, a greenhouse experiment using these consortia in C. quinoa plants showed that, 90 days after inoculation, the morphological traits of both consortia improved. Chemical analysis of metal(loid) contents in the leaves indicated that consortium B reduced the absorption of Cu to 32.1 mg kg−1 and that of Mn to 171.9 mg kg−1. Encapsulation resulted in a significant increase in bacterial survival. This highlights the benefits of using encapsulated microbial consortia from extreme environments, stimulating the growth of C. quinoa, especially in soils with metal(loid) levels that can be a serious constraint for plant growth.

Impact of polyvinyl chloride (PVC) microplastic on growth, photosynthesis and nutrient uptake of Solanum lycopersicum L. (Tomato)

Microplastics (MPs) pollution and their impact on plants have become a global threat, but their effect at the molecular level remains scarce. This study aims to gain insight into the effects of polyvinylchloride microplastic (PVC-MP) on tomato plants at the genetic and protein levels. In this study, we found that increasing concentrations of PVC-MP (2.5, 5,7.5, and 10% w/w) in the soil did not cause any phytotoxic (chlorosis or necrosis) symptoms but it did result in a dose-dependent reduction in plant growth-related parameters, such as height, leaf area, stem diameter, and plant fresh and dry weight. Additionally, the number of secondary roots was reduced while the primary roots were elongated. Furthermore, PVC-MP also caused a significant decrease in light-harvesting pigments chlorophylls, and carotenoids while increasing the level of reactive oxygen species (ROS) and lipid peroxidation in plants. Microscopic analysis of the roots revealed the uptake of PVC-MP of size less than 10 μm. Micro- and macro-element analysis showed changes in concentrations of Ca, Cu, Fe, Mg, Mn, Ni, and Zn, upon PVC-MP exposure. Results from western blotting and q-PCR showed that higher doses of PVC-MP significantly reduced the CO2-fixing enzyme RuBisCO and D1 proteins of PSII at both protein and transcript levels. These findings suggest that lower levels of light-harvesting pigments, D1 protein, RuBisCO, and modulation of nutrient absorption are among the factors responsible for growth suppression in tomato plants upon exposure to PVC-MP. As tomato plants are economically significant crops, an increase in PVC-MP in agricultural fields may have a detrimental influence on crop production, resulting in economic loss.

Malondialdehyde Assays in Higher Plants.

Malondialdehyde is a three-carbon dialdehyde produced as a byproduct of polyunsaturated fatty acid peroxidation widely used as a marker of the extent of lipid peroxidation in plants. There are several methodological approaches to quantify malondialdehyde contents in higher plants, ranging from the simplest, cheapest, and quickest spectrophotometric approaches to the more complex ones using tandem mass spectrometry. This chapter summarizes the advantages and limitations of approaches followed and provides brief protocols with some tips to facilitate the selection of the best method for each experimental condition and application.

Effect of exogenous Ca on the physiology and growth indicators of pakchoi under foliar and root fluorine stress.

Fluorine (F) is not an essential element for vegetation and excessive F can be phytotoxic to plant growth, which can cause fluorosis to human beings by ingesting F-contaminated plant. Although there have been some studies focusing on the toxicity of F to plants and the retarding effect of Ca to F-stress plant, atmospheric F contamination to vegetation and the role of the application of foliar Ca are scantly reported. This study investigated several biochemical parameters to evaluate F toxicity under both F-exposure (root and leaf F-exposure) and the remedial effects of foliar Ca. The results showed that F concentration of pakchoi leaves was correlated with exogenous F level positively in both foliar and root F-exposure series, and F concentration of pakchoi roots was only changed under root F-exposure treatments. Ca supplement (0.5g/L and 1g/L) significantly decreased plant F concentration. Both F-exposure treatments caused lipid peroxidation in plants and exogenous Ca alleviated the toxicity of F to pakchoi. Meanwhile, chlorophyll-a concentration was decreased by foliar and root F, whereas chlorophyll-b concentration was only affected by foliar F, and chlorophyll-a concentration could be elevated by exogenous Ca but chlorophyll-b could not. It was concluded that both atmospheric and root F can impair pakchoi growth and disturb photosynthesis, and foliar Ca showed an ameliorative effect to F toxicity of pakchoi through alleviating chlorophyll decomposition, increasing protein content and alleviating oxidative damage.

Revealing the molecular mechanisms of zinc accumulation and zinc deficiency responses in quinoa, analyzed by high-throughput gene expression profiling under zinc depletion and resupply

Zinc (Zn) is an essential micronutrient for plant growth and development, but the soil available Zn is low in arable land worldwide. Therefore, crop Zn deficiency is a serious issue that threatens the sustainable development of agriculture. Quinoa (Chenopodium quinoa Willd.) is a high-efficiency Zn utilization crop. However, the molecular regulatory mechanisms underlying Zn uptake and Zn deficiency response in quinoa remain largely unclear. Here, using the method of Zn depletion and resupply, we investigated Zn deficiency responses in the hydroponic-grown quinoa seedlings by integrating physiol-biochemical and transcriptomic analyses. Zn depletion leads to H2O2 accumulation and lipid peroxidation in plants. Accordingly, the increased enzyme activities of superoxide dismutase and peroxidase alleviate Zn deficiency-induced oxidative damage in quinoa roots. Subsequently, a genome-wide transcriptome analysis revealed that the expression of genes encoding Zn sensors bZIP19/23 and metal transporters was upregulated in Zn-depleted plants but downregulated in Zn-resupplied plants. Interestingly, the high expression of several iron (Fe) deficiency-responsive transcription factors/transcription regulator genes may not be induced by Fe status in Zn-depleted plants, suggesting that the expression of these genes may be directly induced by Zn deficiency and subsequently regulate micronutrient homeostasis in plants. Zn depletion decreased the contents of indoacetic acid, trans-zeatin-riboside, abscisic acid and salicylic acid 2-O-β-d-glucose but increased the jasmonic acid content in quinoa roots. These results collectively indicated that Zn deficiency affects plant growth and development by modulating phytohormone pathways. Our results provide comprehensive insight into the mechanism of Zn uptake and Zn deficiency response in quinoa and provide a theoretical basis for breeding Zn-efficient crops.

The combination of red and blue light increases the biomass and steroidal saponin contents of Paris polyphylla var. yunnanensis

Red and blue light regulate plant development and metabolism. Paris polyphylla var. yunnanensis, for which there is great demand, is a medicinal plant mainly distributed in China and other parts of Asia. However, the effects of red and blue light on the growth and metabolites of P. polyphylla var. yunnanensis remain unknown. This study evaluated the effects of red (R), blue (B), and red-blue composite light (1 R:1B, 2 R:1B, 3 R:1B) on plant growth and accumulation of steroidal saponins (polyphyllin I, II, VI, and VII) in P. polyphylla var. yunnanensis. The results showed that red and 2 R:1B light significantly increased the net photosynthetic rate and the fresh weight of P. polyphylla var. yunnanensis. Also the combined light, especially 3 R:1B, alleviated the damage to membrane lipid peroxidation in plants. Metabolomic analysis showed that different light treatments, especially 2 R:1B, significantly upregulated the levels of metabolites in metabolic pathways related to carbon and nitrogen balance, energy metabolism, and secondary metabolism in P. polyphylla var. yunnanensis leaves. Furthermore, 1 R:1B and 2 R:1B light treatments promoted the accumulation of steroidal saponins, such as polyphyllin I and VI in rhizomes of P. polyphylla var. yunnanensis. Based on the above results, the red-blue composite light (2 R:1B) could be considered as a suitable light treatment to increase the biomass and steroidal saponin contents of P. polyphylla var. yunnanensis.

Does the type of substrate influence growth and antioxidant systems? Case study of Myracrodruon urundeuva under water deficit

• The type of substrate and water deficit influences growth and the antioxidant response in Myracrodruon urundeuva . • The intensity of the water deficit varies depending on the composition of the substrate, which is influenced by the physicochemical mechanisms of the soil. • The MDA is an important marker of stress in Myracrodruon urundeuva. This study aimed to evaluate the physiological responses of M. urundeuva to conditions of differing water availability and substrates. The study was carried out in a greenhouse using three-month-old plants grown in sand or sandy loam soil under conditions of continuous watering (CW) or water deficit (WD) for 30 days. Subsequently, the plants subjected to water deficiency were irrigated for 15 days. All reviews were conducted at 30 and 45 days, corresponding to the period of water restriction and recovery, and evaluations were performed of absolute growth rates stem height, leaf number, the enzymatic activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), as well as hydrogen peroxide (H 2 O 2 ), and malondialdehyde (MDA) levels. Plants subjected to water deficit showed a reduction in growth parameters, an increase in antioxidant enzyme, activities, and higher H 2 O 2 and MDA concentrations, with differences between soil types. At 45 days, the growth of rehydrated plants continued to be reduced in both substrates, and except for plants grown in sand. CAT activity was increased in these rehydrated plants. In contrast, SOD activity was reduced by 35% in plants rehydrated in substrate. Plants grown in sandy loam soil had higher levels of MDA under both water conditions at 45 days. In conclusion, we corroborate the hypothesis that the greatest damage occurred by lipid peroxidation in plants in sand under deficit, however antioxidant enzymes showed increased activity in plants in soil with no difference in growth reductions under deficit, although greater heights were observed in plants grown in the sandy loam soil after 45 days. The understanding of the responses of M. urundeuva to water deficit in different substrates is important for supporting future studies on the impacts of climate change on the vegetation present in different soil types in the Caatinga.

Selenium: a potent regulator of ferroptosis and biomass production

Emerging evidence supports the notion that selenium (Se) plays a beneficial role in plant development for modern crop production and is considered an essential micronutrient and the predominant source of plants. However, the essential role of selenium in plant metabolism remains unclear. When used in moderate concentrations, selenium promotes plant physiological processes such as enhancing plant growth, increasing antioxidant capacity, reducing reactive oxygen species and lipid peroxidation and offering stress resistance by preventing ferroptosis cell death. Ferroptosis, a recently discovered mechanism of regulated cell death (RCD) with unique features such as iron-dependant accumulation of lipid peroxides, is distinctly different from other known forms of cell death. Glutathione peroxidase (GPX) activity plays a significant role in scavenging the toxic by-products of lipid peroxidation in plants. A low level of GPX activity in plants causes high oxidative stress, which leads to ferroptosis. An integrated view of ferroptosis and selenium in plants and the selenium-mediated nanofertilizers (SeNPs) have been discussed in more recent studies. For instance, selenium supplementation enhanced GPX4 expression and increased TFH cell (Follicular helper T) numbers and the gene transcriptional program, which prevent lipid peroxidase and protect cells from ferroptosis. However, though ferroptosis in plants is similar to that in animals, only few studies have focused on plant-specific ferroptosis; the research on ferroptosis in plants is still in its infancy. Understanding the implication of selenium with relevance to ferroptosis is indispensable for plant bioresource technology. In this review, we hypothesize that blocking ferroptosis cell death improves plant immunity and protects plants from abiotic and biotic stresses. We also examine how SeNPs can be the basis for emerging unconventional and advanced technologies for algae/bamboo biomass production. For instance, algae treated with SeNPs accumulate high lipid profile in algal cells that could thence be used for biodiesel production. We also suggest that further studies in the field of SeNPs are essential for the successful application of this technology for the large-scale production of plant biomass.

Salt Priming as a Smart Approach to Mitigate Salt Stress in Faba Bean (Vicia faba L.).

The present investigation aims to highlight the role of salt priming in mitigating salt stress on faba bean. In the absence of priming, the results reflected an increase in H2O2 generation and lipid peroxidation in plants subjected to 200 mM salt shock for one week, accompanied by a decline in growth, photosynthetic pigments, and yield. As a defense, the shocked plants showed enhancements in ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), peroxidase (POX), and superoxide dismutase (SOD) activities. Additionally, the salt shock plants revealed a significant increase in phenolics and proline content, as well as an increase in the expression levels of glutathione (GSH) metabolism-related genes (the L-ascorbate peroxidase (L-APX) gene, the spermidine synthase (SPS) gene, the leucyl aminopeptidase (LAP) gene, the aminopeptidase N (AP-N) gene, and the ribonucleo-side-diphosphate reductase subunit M1 (RDS-M) gene). On the other hand, priming with increasing concentrations of NaCl (50–150 mM) exhibited little significant reduction in some growth- and yield-related traits. However, it maintained a permanent alert of plant defense that enhanced the expression of GSH-related genes, proline accumulation, and antioxidant enzymes, establishing a solid defensive front line ameliorating osmotic and oxidative consequences of salt shock and its injurious effect on growth and yield.

Ferroptosis in plants: regulation of lipid peroxidation and redox status.

Regulated cell death (RCD) is an essential process that plays key roles along the plant life cycle. Unlike accidental cell death, which is an uncontrolled biological process, RCD involves integrated signaling cascades and precise molecular-mediated mechanisms that are triggered in response to specific exogenous or endogenous stimuli. Ferroptosis is a cell death pathway characterized by the iron-dependent accumulation of lipid reactive oxygen species. Although first described in animals, ferroptosis in plants shares all the main core mechanisms observed for ferroptosis in other systems. In plants as in animals, oxidant and antioxidant systems outline the process of lipid peroxidation during ferroptosis. In plants, cellular compartments such as mitochondria, chloroplasts and cytosol act cooperatively and coordinately to respond to changing redox environments. This particular context makes plants a unique model to study redox status regulation and cell death. In this review, we focus on our most recent understanding of the regulation of redox state and lipid peroxidation in plants and their role during ferroptosis.

Amendments and bioaugmentation enhanced phytoremediation and micro-ecology for PAHs and heavy metals co-contaminated soils

Co-existence of polycyclic aromatic hydrocarbons (PAHs) and multi-metals challenges the decontamination of large-scale contaminated sites. This study aims to comprehensively evaluate the remediation potential of intensified phytoremediation in coping with complex co-contaminated soils. Results showed that the removal of PAHs and heavy metals is time-dependent, pollution-relevant, and plant-specific. Removal of sixteen PAHs by Medicago sativa L. (37.3%) was significantly higher than that of Solanum nigrum L. (20.7%) after 30 days. S. nigrum L. removed higher amounts of Cd than Zn and Pb, while M. sativa L. uptake more Zn. Nevertheless, amendments and microbial agents significantly increased the phytoremediation efficiency of pollutants and shortened the gap between plants. Cd removal and PAHs dissipation reached up to 80% and 90% after 90 days for both plants. Heavy metal stability in soil was promoted after the intensified phytoremediation. Plant lipid peroxidation was alleviated, regulated by changed antioxidant defense systems (superoxide dismutase, peroxidase, catalase). Soil enzyme activities including dehydrogenase, urease, and catalase increased up to 5-fold. Soil bacterial diversity and structure were changed, being largely composed of Proteobacteria, Actinobacteria, Patescibacteria, Bacteroidetes, and Firmicutes. These findings provide a green and sustainable approach to decontaminating complex-polluted environments with comprehensive improvement of soil health.

The overexpression of NCED results in waterlogging sensitivity in soybean

Soil waterlogging limits plant growth and has a major impact on agricultural productivity. Here, we tested the hypothesis that the overexpression of the NCED gene improves waterlogging and reoxygenation tolerance in soybean plants. This was tested using a transgenic soybean line overexpressing the NCED gene (2Ha11) and the conventional cultivar BRS184 (wild-type; WT), which is the genetic background of the 2Ha11 line. Plants at vegetative (V6) and reproductive (R2) stages were exposed to waterlogging for 60 h and posterior reoxygenation for an additional 60 h. Overall, the NCED overexpression increased the levels of lipid peroxidation in plants exposed to waterlogging and posterior reoxygenation while decreased the antioxidant activity and alcohol dehydrogenase activity. In addition, NCED overexpression decreased seed weight and grain yield in the 2Ha11 line exposed to waterlogging at the reproductive stage. Taken together, these results suggest that the overexpression of NCED triggers an increased waterlogging sensitivity in soybean plants especially when they are exposed to waterlogging at the reproductive stage.

Exogenous melatonin protects alfalfa (Medicago sativa L.) seedlings from drought-induced damage by modulating reactive oxygen species metabolism, mineral balance and photosynthetic efficiency

• Data on melatonin-mediated drought tolerance in alfalfa was provided. • Drought is a constraint on the growth and establishment of seedlings. • The results accurately characterize the risk of abiotic stress in the environment. • These findings help to find sustainable strategy-enabled successful cultivation of alfalfa. Drought stress is a severe global environmental concern for the growth and development of alfalfa ( Medicago sativa L.), which is crucial for agricultural sustainability owing to its high feed value and economic prospects. Melatonin (MT) has emerged as a multifaceted biomolecule that plays a fundamental role in regulating plants' multiple environmental stresses. However, the significant effect of exogenous MT on drought stress tolerance in the alfalfa forage crops remains inexpressible. We investigated the effects of foliar-sprayed melatonin at different doses (50, 100, 200 μM) on alfalfa seedlings' growth and physiological responses under drought stress. Our results showed that drought stress reduced morphological growth attributes (by 12 to 54%), gas exchange parameters (by 37 to 88%), photosynthetic pigments (Chl a, and Chl b contents by 29%, and 40%), mineral contents, and increased lipid peroxidation (by 69%) and accumulation of reactive oxygen species (ROS) in alfalfa plants. In contrast, exogenous foliar application of MT significantly revived growth characteristics, boosted antioxidant enzyme activities, improved photosynthetic performance, decreased ROS-induced oxidative damage by increasing plant mineral elements, and lowered lipid peroxidation in plants under drought stress. In addition, MT also stimulated the accumulation of total soluble sugar and proline content by 48% and by 75% respectively, which were positively associated with improved leaf water status in drought-stressed plants. Meanwhile, our findings revealed that the highest efficiency was achieved at 100 μM melatonin. In conclusion, these findings bring a new perspective on melatonin-mediated drought stress tolerance and provide a foundational understanding of alfalfa's future cultivation in drought-prone regions globally.

Epibrassinolide improves the growth performance of Sedum lineare upon Zn stress through boosting antioxidative capacities.

As an essential element, zinc (Zn) can improve or inhibit the growth of plants depending on its concentrations. In this study, the effects of 24-Epibrassinolide (EBR), one well-known steroid phytohormone regulating plant growth and alleviating abiotic stress damage, on morphological parameters and antioxidant capacities of Sedum lineare were investigated under different Zn doses. Compared to plants only exposed to Zn, simultaneously foliar application of 0.75 μM EBR significantly improved multiple morphological characteristics and such growth-improving effects were more significant at high Zn concentrations. At a detrimental 800 μM Zn, EBR benefitted plant growth most prominently, as shown by that the stem length, fresh weight and internode length were increased by 111%, 85% and 157%, respectively; than Zn solely treated plants. EBR spray also enhanced both the activities of antioxidant enzymes such as peroxidase (POD), ascorbate peroxidase (APX), glutathione reductase (GR), and the contents of antioxidative agents including ascorbic acid (AsA) and glutathione (GSH), which in turn decreased the accumulation of reactive oxygen species (ROS) and alleviated the lipid peroxidation in plants. Thus, by demonstrating that EBR could help S. lineare resist high-zinc stress through strengthening the antioxidant system, this work provided a new idea for expanding the planting range of Crassulaceae plants in heavy metal contaminated soil for phytoremediation purpose in the future.

Влияние антропогенного загрязнения среды г. Тюмени на показатели жизнедеятельности травянистых растений

The purpose of this study was the investigation of lipid peroxidation products and photosynthetic pigment content in cells of herbs of various species in conditions of anthropogenic pollution of Tyumen. The material for the research was collected near different plants of Tyumen: metallurgical, engine, oil refinery, battery manufacturing as well as highway pollution. The following species of plants were analysed: coltsfoot (Tussilago farfara), red clover (Trifolium rubens), chamomile (Matricaria chamomilla) and wild vetch (Vicia cracca). Heavy metal concentration in soils of urban areas turned out to be elevated compared to background sites. Especially high heavy metal content was registered near metallurgical and battery manufacturing plants. Changes in photosynthetic pigment concentration turned out to be species-specific. An increase in photosynthetic pigments was obtained in chamomile cells, while in other plants oppression of photosynthetic apparatus was revealed. Concentration of lipid peroxidation cells of chamomile, meadow grass and wild vetch was increased compared to background site, while in coltsfoot and red clover it decreased. Heavy metal content in soils positively correlated with lipid peroxidation in plants. Oxidation stress in chamomile cells created energetic starvation, which was reflected in a positive correlation between photosynthetic pigments and the concentration of conjugated dienes in cells.

Phenotype, Physiology, and Gene Expression of Barley Seedlings in Response to Nano Zinc Oxide Stress

In recent years, zinc oxide nanoparticles (ZnO NPs) have been widely used as zinc fertilizers and pesticides. The use of ZnO NPs in this way can provide benefits to humans, but also has potential risks. ZnO NPs inevitably enter the environment during their production and use, which affects the ecological environment and crop growth. In order to investigate the phenotype, physiology, and gene expression of barley (Hordeum vulgare L.) seedlings under ZnO NPs stress, the barely cultivars ZJU3 (P21), Golden Promise (GP) and L23 were chosen for study. Different ZnO NPs concentrations were applied to compare the physiological and biochemical indexes of the barley seedlings and the responses of six stress-related genes, when seedlings were cultured to the two-leaf stage through hydroponics. The results showed that the density of brown spots on the leaf surface increased with increasing ZnO NPs concentration. ZnO NPs stress inhibited the root growth of barley seedlings, and P21 was the most sensitive. Furthermore, ZnO NPs stress could stimulate plants to produce a large number of reactive oxygen species (ROS), resulting in an imbalance between the production and removal of ROS and membrane lipid peroxidation in plants. This imbalance inhibited the growth and development of the barley seedlings. With increasing ZnO NPs concentration, the activity of superoxide dismutase was gradually increased, the activity of catalase was progressively decreased, and the contents of malondialdehyde and proline were increased. Compared with the control, among six stress-related genes, the expression levels of five genes were downregulated and one gene was upregulated in the experimental group. This study preliminarily revealed the toxic effect of ZnO NPs on seedlings and the effect on the expression of stress-related resistance genes in different barley varieties.

Co-application of indigenous arbuscular mycorrhizal fungi and nano-TiO2 reduced Cd uptake and oxidative stress in pre-flowering cowpea plants

The symbiotic association between plant roots and arbuscular mycorrhizal fungi (AMF) promotes plant growth, and reduces toxic metals accumulation in plants. In this study, the effect of inoculation with indigenous AMF ( Glomus Spp.) and co-application of AMF and nano-TiO 2 on Cd accumulation on activities of stress enzymes in cowpea at pre-flowering stage was examined. Soil substrates were spiked with either Cd (10 mg/kg) and inoculated with either AMF suspension (7 ml) or AMF+ n TiO 2 (200 mg/kg). The results showed that inoculation with AMF and AMF+ n TiO 2 promoted germination and chlorophyll contents by at least 12% and 45%, respectively. As envisaged, AMF+ n TiO 2 reduced uptake and decreased translocation of Cd to above-ground biomass better than inoculation solely with AMF. In the aspect of Cd toxicity assessed by enzymes activity, sole AMF inoculation and AMF+ n TiO 2 had varied effects on the stress enzymes activity. However, n TiO 2 interacted synergistically with AMF to improve stress tolerance by reducing the lipid peroxidation in plants (in term of the amount of malondialdehyde) more than sole inoculation with AMF. In conclusion, the present study demonstrated that there is stimulatory effect of nano-TiO 2 on the activity of AMF in alleviating Cd stress in pre-flowering cowpea. • Combination of AMF and n TiO 2 reduced root uptake and translocation of Cd. • Synergistic interaction between AMF and n TiO 2 reduced MDA content. • Nano-TiO 2 portends stimulatory effect on AMF to reduce Cd toxicity.

Alleviation of allelochemical stress-induced growth inhibition and oxidative damage in lettuce under closed hydroponics through electro-degradation

Successive lettuce cultivation in closed hydroponics using the same nutrient solution causes the excess production and accumulation of allelochemicals. The accumulated allelochemicals induce oxidative damage and lipid peroxidation in plants leading to growth inhibition. In this study, we investigated the allelochemicals that induced oxidative damage and lipid peroxidation in lettuce grown in a once used non-renewed nutrient solution (1NR) and a twice used non-renewed nutrient solution (2NR) obtained from the successive cultivation and the alleviation of these damages through electro-degradation (ED). The 1NR solution was used for six weeks for a one-time lettuce cultivation while the 2NR solution was used for twelve weeks for a two-times lettuce cultivation. The results showed that the allelochemical stress caused growth inhibition in the lettuce in both the 1NR and 2NR solutions. It was observed that there was a higher generation of H2O2 and O2.– as well as a lower activity of the antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (POD), and ascorbate peroxidase (APX) in the roots of the plants grown in both the 1NR and 2NR solutions compared to plants grown in the new nutrient solution. The higher level of lipid peroxidation due to the higher MDA (malondialdehyde) content and higher soluble protein content were also observed in the roots of those plants. It was evident that lettuce root damage occurred due to accumulation of the allelochemicals in the 1NR and 2NR solutions. These damaged roots could not function normally nor uptake water and minerals from the culture solution. As a result, retarded lettuce growth was observed in the 1NR and 2NR solutions. The oxidative damage, soluble protein content, lipid peroxidation and ultimately growth retardation were more pronounced in the plants grown in the 2NR solution compared to the plants grown in the 1NR solution. The application of ED to the 1NR and 2NR solutions maintained the plant growth through less oxidative damage, soluble protein production and lipid peroxidation as was observed in the plants grown with the new nutrient solution. Therefore, the ED of a non-renewed culture solution would alleviate the allelochemical stress in lettuce under recycled hydroponics.

Biochemical and morphophysiological strategies of Myracrodruon

In view of the ecological, social, and economic importance of Myracrodruon urundeuva Allemao, the objective of this study was to investigate the strategies of this species under drought during its initial phase of development. Two-month-old plants were cultivated under continuous irrigation or no irrigation for 20 d. After this period, the water-stressed plants were rehydrated for 20 d. Physiological, biochemical, and anatomical variables were evaluated on 20th and 40th day. Water deficit (25 and 85 % leaf relative content) caused senescence followed by leaf abscission. Growth in height was negatively affected by water deficit (37 % reduction). A decrease in the thickness of the mesophyll was accompanied by a decrease of the total chlorophyll content. Water deficit affected saccharide metabolism and altered cellular component dynamics. Enzyme activities were higher during the rehydration period than during the water stress. There was no increase in lipid peroxidation in plants subjected to water deficit. A reduction in the stomatal opening during water stress was a strategy of reducing water loss through transpiration.

Vitamin E in Plants: Biosynthesis, Transport, and Function.

Vitamin E, which includes both tocopherols and tocotrienols, comprises lipid-soluble antioxidants that modulate lipid peroxidation. Recently, significant advances have been made in our understanding of vitamin E biosynthesis, transport, and function. The phytyl moiety from chlorophyll degradation is used for tocopherol biosynthesis. An α-tocopherol-binding protein (TBP) has been identified in tomato (SlTBP) serving in intraorganellar vitamin E transport in plants. Moreover, α-tocopherol not only scavenges free radicals through flip-flop movements in the lipid bilayer, but may also contribute to fine-tuning the transmission of specific signals outside chloroplasts. Vitamin E, and α-tocopherol in particular, appear to be essential for plant development and help to provide the most suitable response to a number of environmental stresses.