Oxidative Stress In Plants Research Articles

Exogenous chlorogenic acid alleviates oxidative stress in apple leaves by enhancing antioxidant capacity

Considered to be an antioxidant, chlorogenic acid is involved in resistance to insects and pathogens, and beneficial effects on human health. However, little is known about the antioxidant functions of chlorogenic acid against oxidative stress in plants. In this study, we studied the potential role of exogenous chlorogenic acid in alleviating methyl viologen-mediated oxidative stress in detached leaves of apple (Malus domestica Borkh). The results showed that exogenous chlorogenic acid availably relieved the decreases in chlorophyll concentrations and maximum potential Photosystem II efficiency. Exogenous chlorogenic acid also effectively reduced membrane damage and lipid oxidation and stimulated activity of antioxidant enzymes, including peroxidase, catalase, and polyphenol oxidase. It is noteworthy that exogenous chlorogenic acid improves antioxidant activity of apple leaf under oxidative stress using DPPH, ABTS, and FRAP assays. In addition, the concentration of phenolics increased remarkably in response to chlorogenic acid application after methyl viologen exposure. Furthermore, exogenous chlorogenic acid also changed the transcription levels of related genes for antioxidant enzymes and phenolic metabolism. These results suggest that chlorogenic acid can be effective antioxidants protecting the plants against oxidative stress by enhancing antioxidant capacity.

Silicon-mediated cellular resilience mechanisms against copper toxicity and glandular trichomes protection for augmented artemisinin biosynthesis in Artemisia annua

The micronutrients could cause severe toxicity to plants at higher concentrations. In this investigation, copper (Cu) toxicity caused morphological and cellular damages to the Artemisia annua L. plants but application of silicon (Si) ameliorated the damaging effects of Cu. Copper toxicity reduced the lengths of shoot and root and also fresh and dry weights of shoot of the plants. However, exogenous application of Si to Cu-treated plants significantly alleviated the harmful effect on plants by metal stress. Copper stress also lowered the photosynthetic potential and content of total chlorophyll as well as hindered the chlorophyll fluorescence; however, Si supplementation recovered the negative impacts of Cu in the plants. The treatment of Cu resulted in accumulation of this metal in roots and shoots of A. annua plants. Deposition of Cu resulted in oxidative stress in plants as evident by increase in 2-thiobarbituric acid reactive substances (TBARS) content and catalase (CAT), peroxidase (POX) and superoxide dismutase (SOD) enzyme activities. However, addition of Si prevented adverse effects of Cu toxicity and prevented excess of Cu in root and shoot tissues and TBARS content in the cells of disturbed plants. The significant deleterious impact of high concentrations of Cu on density and ultrastructure of glandular trichomes and artemisinin content was also noticed. Furthermore, the Si supplementation improved the density of glandular trichomes and protected the plant tissues from Cu toxicity, thereby upregulating artemisinin biosynthesis. Therefore, the results indicated that the exogenous application of Si protect A. annua plants from Cu toxicity by preventing deposition of Cu in root and shoot tissues, by increasing the antioxidant capacity, which maintained the structure and integrity of leaves and also helps in increased artemisinin production.

Mechanisms and Signaling Pathways of Salt Tolerance in Crops: Understanding from the Transgenic Plants

Soil salinization is a serious agricultural issue that is severely affecting crop production across the world. Salt induced stresses are mainly included osmotic and ionic stresses, which could lead to other stresses e.g., oxidative stress in plants. The evolved plant mechanisms in salt tolerance are categorized into osmotic tolerance and ionic homeostasis mediated by ion exclusion and ions sequestration into vacuole. Osmotic tolerance involves long-distance signaling which still has many unknowns in crops, while ionic homeostasis is achieved by Na+/K+/H+ transporters and H+-pumps. Besides, the mechanisms of salt tolerance are regulated by various signaling pathways and transcription factors. A better understanding on the mechanisms of salt tolerance and its involved candidate genes is a prerequisite for increasing/maintaining yield potential of crops in saline soils. This review focuses on various mechanisms, signaling pathways and transcriptional regulations of salt tolerance in crops. We also review the various examples of underlying candidate genes that have been engineered to develop the salt tolerant crops, and may also have worth in next crop breeding.

Metabolic rearrangements in imbibed maize (Zea mays L) embryos in the presence of oxidative stressors

Cadmium (Cd) is a metal known to generate oxidative stress in plants and may be particularly harmful during germination. Herein, the growth and metabolic rearrangements of maize embryo axes subjected during the imbibition stage to Cd ions and other two well-known oxidative stressors, methyl viologen (MV) and hydrogen peroxide (H2O2), were assessed for 48 h. Similar decreases in embryo's length were detected for all stressed axes up to 48 h of imbibition. By this time, treated embryos revealed greater accumulation of reactive oxygen species (ROS) and increased levels of carbonylated and ubiquitinated proteins. The proteolytic activities were intensely enhanced in the treated axes, particularly at 48 h of imbibition, and several antioxidant enzymes were induced in most cases. NMR spectroscopy followed by principal component analysis (PCA) and hierarchical cluster analysis (HCA) showed that a large proportion of polar metabolites, mainly amino acids and organic acids, were decreased under stress conditions, while carbohydrates were increased at 48 h of imbibition, with significant increases in glucose and raffinose for treated embryos relatively to controls. We demonstrated that maize embryo axes were capable of shifting their metabolism to improve their antioxidant defense system, at the expense of their growth. Under these adverse conditions, proteolysis seems to play a key role by providing free amino acids needed for the de novo synthesis of defense-related proteins.

Soil Amendment with Biosolids and Inorganic Fertilizers: Effects on Biochemical Properties and Oxidative Stress in Basil (Ocimum basilicum L.)

We investigated changes in biochemical activity of a soil cultivated with Ocimum basilicum L. plants and in the oxidative stress of plants caused by the addition of biosolids and inorganic fertilizer. A greenhouse experiment was set up; it consisted of pots containing basil plants to which different treatments with biosolids and fertilizers were added. After 10 and 210 days of the incorporation of the treatments, both the biochemical properties and oxidative stress of the plants were evaluated. Mineralization of nitrogen (N) and respiratory activity increased with a higher dose of biosolid after 10 days of application. After 210 days, there were no changes in the mineralization of N and respiratory activity, catalase showed an increase, while microbial biomass carbon decreased. In relation to the oxidative stress, there was a decrease in the anthocyanin antioxidant capacity, and 2,2-diphenyl-1-picrylhydrazyl (DPPH), total flavonoids, and phenolic compounds were observed in soils treated with biosolids. The results indicated that the biochemical properties of the soil were favored in the presence of biosolids because they increased, especially after 10 days of application. The antioxidant capacity decreased in the presence of biosolids, which suggests that the amendment does not affect such capacity, and therefore oxidative stress could be reduced.

Reactive Oxygen Species and Antioxidant Defense in Plants under Abiotic Stress: Revisiting the Crucial Role of a Universal Defense Regulator.

Global climate change and associated adverse abiotic stress conditions, such as drought, salinity, heavy metals, waterlogging, extreme temperatures, oxygen deprivation, etc., greatly influence plant growth and development, ultimately affecting crop yield and quality, as well as agricultural sustainability in general. Plant cells produce oxygen radicals and their derivatives, so-called reactive oxygen species (ROS), during various processes associated with abiotic stress. Moreover, the generation of ROS is a fundamental process in higher plants and employs to transmit cellular signaling information in response to the changing environmental conditions. One of the most crucial consequences of abiotic stress is the disturbance of the equilibrium between the generation of ROS and antioxidant defense systems triggering the excessive accumulation of ROS and inducing oxidative stress in plants. Notably, the equilibrium between the detoxification and generation of ROS is maintained by both enzymatic and nonenzymatic antioxidant defense systems under harsh environmental stresses. Although this field of research has attracted massive interest, it largely remains unexplored, and our understanding of ROS signaling remains poorly understood. In this review, we have documented the recent advancement illustrating the harmful effects of ROS, antioxidant defense system involved in ROS detoxification under different abiotic stresses, and molecular cross-talk with other important signal molecules such as reactive nitrogen, sulfur, and carbonyl species. In addition, state-of-the-art molecular approaches of ROS-mediated improvement in plant antioxidant defense during the acclimation process against abiotic stresses have also been discussed.

Coffea arabica seedlings genotypes are tolerant to high induced selenium stress: Evidence from physiological plant responses and antioxidative performance

Selenium (Se) is considered a beneficial element to higher plants based on its regulation of antioxidative system under abiotic or biotic stresses. However, the limit of beneficial and toxic physiological effects of Se is very narrow. In the present study, the antioxidant performance, nutritional composition, long-distance transport of Se, photosynthetic pigments, and growth of Coffea arabica genotypes in response to Se concentration in solution were evaluated. Five Coffea arabica genotypes (Obatã, IPR99, IAC125, IPR100 and Catucaí) were used, which were grown in the absence and presence of Se (0 and 1.0 mmol L−1) in nutrient solution. The application of 1 mmol L−1 Se promoted root browning in all genotypes. There were no visual symptoms of leaf toxicity, but there was a reduction in the concentration of phosphorus and sulfur in the shoots of plants exposed to high Se concentration. Except for genotype Obatã, the coffee seedlings presented strategies for regulating Se uptake by reducing long-distance transport of Se from roots to shoots. The concentrations of total chlorophyll, total pheophytin, and carotenoids were negatively affected in genotypes Obatã, IPR99, and IAC125 upon exposure to Se at 1 mmol L−1. H2O2 production was reduced in genotypes IPR99, IPR100, and IAC125 upon exposure to Se, resulting in lower activity of superoxide dismutase (SOD), and catalase (CAT). These results suggest that antioxidant metabolism was effective in regulating oxidative stress in plants treated with Se. The increase in sucrose, and decrease in SOD, CAT and ascorbate peroxidase (APX) activities, as well as Se compartmentalization in the roots, were the main biochemical and physiological modulatory effects of coffee seedlings under stress conditions due to excess of Se.

Earthworm Eisenia andrei modulates oxidative stress in bean plants Vicia faba irrigated with treated wastewater.

With respect to reducing the pressure on freshwater resources, treated wastewater (TWW) irrigation represents a sustainable alternative in agriculture. Due to their low quality and variable composition, TWW could entail harmful consequences for living organisms in terrestrial ecosystems. This study aims to evaluate how earthworm (Eisenia andrei) can modulate oxidative stress in bean plants (Vicia faba) that are irrigated over a course of 60 days with two doses of TWW (50 and 100%) in addition to a control condition (0%) irrigated with distilled water. This is achieved by measuring glutathione-S-transferase (GST) activity and malondialdehyde accumulation (MDA) in plants. Furthermore, catalase (CAT), GST, MDA, and acetylcholinesterase (AChE) activities of the earthworms are also assessed. Our results show that growth and physiological parameters are modified when applying TWW irrigation. Moreover, oxidative stress apprehended by GST activity and MDA accumulation is exacerbated in V. faba plants after exposure to increased TWW doses. Similarly, TWW irrigation enhances oxidative stress parameters in earthworms with a crucial decrease in AChE activity. In addition, the presence of earthworms increases growth and physiological parameters; it also results in a significant reduction in GST activity and MDA rate in V. faba plants. Our results provide new insights into the impact of TWW irrigation on soil organisms and the importance of earthworms in the reduction of oxidative stress in plants.

Expression of Antioxidant Enzymes and Changes in Some Physiological Parameters Following the Short-term Heavy Metal Application in Wheat

The aim of this study was to investigate the changes of some biochemical parameters during the amelioration after period o short term treatment of wheat with arsenic, cadmium and lead. A decrease was observed in the experimental groups, in which 15 μM, 30 μM, and 60 μM (arsenic, lead, and cadmium) metal ion mixture was applied, in terms of the germination rate depending on the increased concentration, and a decrease was observed in the root and stem dry weights of the plants in all groups. MDA levels were determined to increase at all doses. It was determined that heavy metals accumulated by increasing in the tissues due to the increased concentration of heavy metals in the heavy metal ion-applied groups. There were significant changes in the expression levels of antioxidant enzymes. As a result, it was determined in the study that there were significant changes in some biochemical and physiological parameter�s which are the primary response to oxidative stress in plants exposed to heavy metals, depending on the stress. This reason it can be concluded that arsenic, lead and cadmium contents in media can be the responsible for growth inhibition.

Effect of gibberellic acid on growth, biomass, and antioxidant defense system of wheat (Triticum aestivum L.) under cerium oxide nanoparticle stress.

Recently nanoparticles (NPs) are ubiquitous in the environment because they have unique characteristics which are the reason of their wide use in various fields. The release of NPs into various environmental compartments mainly ends up in the soil through water bodies which is a serious threat to living things especially plants. When present in soil, NPs may cause toxicity in plants which increase significance to minimize NPs stress in plants. Although gibberellic acid (GA) is one of the phytohormones that has the potential to alleviate abiotic/biotic stresses in crops plant, GA-mediated alleviation of cerium oxide (CeO2) NPs in plants is still unknown, despite the large-scale application of CeO2-NPs in various fields. The present study was performed to highlight the ability of foliar-applied GA in reducing CeO2-NPs toxicity in wheat under soil exposure of CeO2-NPs. We observed that CeO2-NPs alone adversely affected the dry weights, chlorophyll contents, and nutrients and caused oxidative stress in plants, thereby reducing plant yield. GA coupled with CeO2-NPs reversed the changes caused by CeO2-NPs alone as indicated by the increase in plant growth, chlorophylls, nutrients, and yield. Furthermore, GA alleviated the oxidative stress in plants by enhancing antioxidant enzyme activities under CeO2-NPs exposure than the NPs alone which further provided the evidence of reduction in oxidative damage in plants by GA. Overall, evaluating the potential of GA in reducing CeO2-NPs toxicity in wheat could provide important information for improving food safety under CeO2-NPs exposure.

Exogenous silicon and salicylic acid applications improve tolerance to boron toxicity in field pea cultivars by intensifying antioxidant defence systems.

Field peas (Pisum sativum L.) are widely cultivated throughout the world as a cool season grain and forage crop. Boron (B) toxicity is caused by high B concentration in the soil or irrigation water, and is particularly problematic in medium or heavier textured soil types with moderate alkalinity and low annual rainfall. Previous studies have indicated that B-toxicity increases oxidative stress in plants, and B-tolerance has been considered an important target in field pea plant breeding programmes. Inducers of tolerance may be a promising alternative for plant breeding. Little research has been conducted on the combined use of silicon (Si) and salicylic acid (SA) to remediate B-toxicity in field peas. The present study revealed the physiological and biochemical plant responses of applying Si+SA under B-toxicity (15mgB L-1) on two Brazilian field pea cultivars (Iapar 83 and BRS Forrageira). A semi-hydroponic experiment was conducted using a completely randomized factorial design (2×5): with two field pea cultivars and five treatments which were formed by individual and combined applications of Si and SA under B-toxicity plus a control (control, B, B+Si, B+SA, and B+Si+SA). Si (2mmolL-1) was applied to plants in two forms (root and leaf), while for SA (36 μmol L-1) only foliar applications were applied. Our results demonstrated that the combined use of exogenous Si+SA in field peas increased tolerance to B-toxicity through an intensified antioxidant plant defence system, resulting in a better regulation of reactive oxygen species (ROS) production and degradation. It significantly increased total chlorophyll and carotenoids contents, the activities of major antioxidant enzymes, and reduced MDA and H2O2 contents, resulting in increased fresh shoot and total plant dry biomass. The application of Si+SA alleviated the inhibitory effects of boron toxicity in field peas, resulting in greater plant growth by preventing oxidative membrane damage through an increased tolerance to B-excess within the plant tissue. Therefore, the use of Si+SA is an important and sustainable strategy to alleviate B-toxicity in field pea cultivation.

Effect of exogenous catechin and salicylic acid on rice productivity under ozone stress: the role of chlorophyll contents, lipid peroxidation, and antioxidant enzymes.

Increasing ozone concentration is one of the oxidative stresses that affects rice yield loss in many countries. Catechin and salicylic acid were proposed as tools for alleviating oxidative stress in plants, but their roles in protecting rice productivity under ozone stress still remained unknown. We investigated the mechanism of catechin and salicylic acid on rice under ozone stress at the vegetative stage and at the reproductive stage. Rice was sprayed with catechin and salicylic acid before exposure to ozone in the range of 100-150ppb (8hday-1). Ozone and salicylic acid led to a decrease in chlorophyll contents, magnesium contents, and stomatal conductance. This evidence led to a decrease in rice productivity and quality. In contrast, under rice + catechin, both ambient air and elevated ozone conditions had to higher rice productivity and quality than under rice alone and rice + salicylic acid conditions. Catechin could mitigate ozone stress in rice plants through maintaining chlorophyll contents, magnesium contents, and stomatal conductance. Moreover, catechin could induce an unregulation ofascorbate peroxidase, and catalase genes led to increasing their antioxidant enzyme activity. Increasing of antioxidant enzyme activity under rice + ozone + catechin conditions attributed to lower lipid peroxidation than under rice + ozone especially at vegetative stage. This study confirmed that catechin, which is naturally found in tea leaves, could be used as an ozone protectant. The protective role of catechin on chlorophyll contents and antioxidant systems at the vegetative stage attributed to maintaining rice yield under ozone stress. Graphical abstract.

Study of salt-stress tolerance and defensive mechanisms in Brassica rapa CAX1a TILLING mutants

Crop production is facing the increase of salinity in soils and irrigation waters. This is a widespread problem that affects crops with high economic importance and reduces yields. Salinity causes oxidative stress in plants which induce complex defensive mechanisms involving the antioxidant system and osmoprotector compounds. Ca2+ plays a pivotal role in counteracting salt stress, and the modification of the Ca2+ vacuolar transporter CAX1 could represent a potential method to improve tolerance to salinity. Three new CAX1 variants in Brassica rapa (BraA.cax1a) were generated using TILLING strategy. The objective of this work is to evaluate the tolerance of these mutants to saline conditions. For this, BraA.cax1a mutants and the parental line R-o-18 were grown in pots under control and saline conditions (150 mM NaCl). Parameters of biomass, ions accumulation, antioxidant compounds concentration and antioxidant enzyme activities, heat shock protein 70 (HSP70) occurrence, and proline (Pro) levels were measured. According to the results, BraA.cax1a-4 mutation provided a higher tolerance to salinity stress. Thus, BraA.cax1a-4 plants showed higher biomass; higher Ca2+ and K+ accumulation in the shoot, a lower Na+/K+ ratio, an enhanced ROS scavenging (increased superoxide dismutase and catalase activities) and an enhanced ascorbate redox state. BraA.cax1a-4 and BraA.cax1a-12 showed higher K+ transport to the shoot which could contribute to their lower lipid peroxidation. In contrast, BraA.cax1a-7 showed a lower antioxidant response. Besides, an increased occurrence of cytosolic and chloroplastic HSP70 isoforms and Pro levels could contribute to protect these B. rapa mutants from saline stress. Therefore, this study identifies a potential useful genotype that could be used to enhance salt tolerance of crops.

Oxidative Stress, Nutritional Disorders, and Gas Exchange in Lettuce Plants Subjected to Two Selenium Sources

Selenium (Se) is microelement beneficial to plants and essential to animals and humans. Supply of Se shows positive effects on plant growth, but high concentrations affect its growth. This study is based on the hypothesis that nutritional disorder and oxidative stress induced by toxic levels of selenium maintain a close correlation with inhibition of photosynthesis net and reduced growth in lettuce plants. In this study, we investigated impact of Se toxicity on gas exchange, oxidative stress indicators, nutritional status, and growth of lettuce plants. Two sources and ten selenium concentrations were evaluated in lettuce according to a completely randomized experimental design in a factorial scheme with two selenium sources (selenite and selenate) and ten selenium concentration (0, 2, 4, 6, 8, 16, 32, 64, 96, 128 μM). Results show that reduction in leaf area and shoot dry matter was high when selenite was supplied to plants. It was achieved due to oxidative stress and nutritional disorder that affected photosynthesis, which resulted in low photosynthesis net. These results were reinforced by strong correlation of photosynthesis with essential nutrient contents and indicators of oxidative stress in plants treated with selenite. However, photosynthesis net was increased with 8 μM concentration of selenate. Lettuce growth was reduced due to oxidative stress and nutritional disorder. The results of this study contribute to clarifying negative modulation of photosynthesis net by higher selenate or selenite concentrations in lettuce plants through growth analysis, nutritional composition, oxidative stress indicators, and gas exchange. The strong or very strong negative correlation between photosynthesis net and oxidative stress indicators (superoxide, peroxide and malondialdehyde), photosynthesis net and chlorophyll a, photosynthesis net, and selenium content support the hypothesis of this study in which selenium-induced damage to the photosynthetic apparatus reduces the growth of lettuce. These results show new evidence on the mechanism of action of selenium toxicity on the photosynthetic machinery of lettuce plants. In addition, the results found show that lettuce plants respond differently to the source and concentration of selenium, with symptoms of toxicity manifesting even in the short exposure time of lettuce plants.

Alleviation of copper toxicity in Daphnia magna by hydrogen nanobubble water

As a novel antioxidant, hydrogen water has been widely used to alleviate oxidative stress in plants as well as in the medical field. However, the function of hydrogen water in environmental toxicology remains unknown. In this study, combining nanobubbles (NBs) and hydrogen water, we investigate the effect and mechanism of hydrogen NB water on copper induced acute toxicity to water fleas (Daphnia magna). The 24-h lethal Cu concentrations at which 50 % of the population die were 84 μg/L in hydrogen NB water and 45 μg/L in control water, confirming that hydrogen NB water effectively alleviated acute Cu toxicity in D. magna. The results were consistent with a significant reduction of Cu uptake and decrease of Cu accumulation in D. magna. As confirmed in fluorescence spectrophotometry and high-content screening system analysis, the hydrogen NB water also significantly reduced the oxidative damage and improved Cu tolerance in D. magna. From the results, it can be inferred that hydrogen NB water alleviates Cu stress in D. magna by depressing Cu bioaccumulation and reducing oxidative stress. The results provide basic data of hydrogen NB water for environmental toxicologists, and also a reference for the application of hydrogen NB water in the environment.

Chromium Bioaccumulation and Its Impacts on Plants: An Overview.

Chromium (Cr) is an element naturally occurring in rocky soils and volcanic dust. It has been classified as a carcinogen agent according to the International Agency for Research on Cancer. Therefore, this metal needs an accurate understanding and thorough investigation in soil–plant systems. Due to its high solubility, Cr (VI) is regarded as a hazardous ion, which contaminates groundwater and can be transferred through the food chain. Cr also negatively impacts the growth of plants by impairing their essential metabolic processes. The toxic effects of Cr are correlated with the generation of reactive oxygen species (ROS), which cause oxidative stress in plants. The current review summarizes the understanding of Cr toxicity in plants via discussing the possible mechanisms involved in its uptake, translocation and sub-cellular distribution, along with its interference with the other plant metabolic processes such as chlorophyll biosynthesis, photosynthesis and plant defensive system.

Interactive role of salicylic acid and nitric oxide on transcriptional reprogramming for high temperature tolerance in lablab purpureus L.: Structural and functional insights using computational approaches

Salicylic acid (SA) and nitric oxide (NO) are considered as putative plant growth regulators that are involved in the regulation of an array of plant’s growth and developmental functions under environmental fluctuations when applied at lower concentrations. The possible involvement of NO in SA induced attenuation of high temperature (HT) induced oxidative stress in plants is however, still vague and need to be explored. Therefore, the present study aimed to investigates the biochemical and physiological changes induced by foliar spray of SA and NO combinations to ameliorate HT induced oxidative stress in Lablab purpureus L. Foliar application of combined SA and NO significantly improved relative water content (27.8 %), photosynthetic pigment content (67.2 %), membrane stability (45 %), proline content (1.0 %), expression of enzymatic antioxidants (7.1–18 %) along with pod yield (1.0 %). Heat Shock Factors (HSFs) play crucial roles in plants abiotic stress tolerance, however there structural and functional classifications in L. purpureus L. is still unknown. So, In-silico approach was also used for functional characterization and homology modelling of HSFs in L. purpureus. The experimental findings depicted that combine effect of SA and NO enhances tolerance in HT stressed L. purpureus L. plants by regulating physiological functions, antioxidants, expression and regulation of stress-responsive genes via transcriptional regulation of heat shock factor.

Elucidating physiological and biochemical alterations in giant duckweed (Spirodela polyrhiza L. Schleiden) under diethyl phthalate stress: insights into antioxidant defence system.

BackgroundThe emollient properties of phthalates have led to their extensive production and intense use in plastic products. Owing to their weak covalent bonding with the plastic polymers, phthalates enter into the environment during their manufacturing, processing, disposal, consequently found their way directly into water sources, soil, and sediments.MethodsThe present study envisaged the toxic effects of diethyl phthalate (DEP) on physiological and biochemical attributes of Spirodela polyrhiza, when exposed to various concentrations of DEP (0, 10, 20, 40, 80, 100, 200, and 400 ppm) for short term exposure period of seven days.ResultsPlants of S. polyrhiza accumulated significant amount of DEP (112 mg kg−1 fw) when exposed to various concentrations of DEP for seven days. Results depicted that DEP toxicity significantly (p ≤ 0.05) affected growth parameters and pigments in treated S. polyrhiza as compared to control. Further, high doses of DEP (400 ppm) caused significant decrement in carbohydrate (86%), protein (76%) and elevation in MDA content (42%). Meanwhile, DEP altered the activities of antioxidant enzymes (SOD, CAT, APX, GPX and GR) along with the induction of enhanced levels of proline, electrolyte leakage and phenolic content. Scanning electron microscopic and confocal studies also confirmed oxidative stress in plants under DEP stress.ConclusionsPresent findings will help understand the accumulation, tolerance, and detoxification mechanisms of DEP by S. polyrhiza to counteract the effects of reactive oxygen species (ROS), along with the evaluation of environmental threat for aquatic plants in aquatic ecosystems.

Unveiling Plant-Beneficial Function as Seen in Bacteria Genes from Termite Mound Soil

The use of termite mound soils in enhancing soil fertility and plant growth, especially in areas with poor soil conditions, has been recommended by many research studies. Most of these recommendations are, however, based on the high nutrient levels in termite mound soils. Thus, this study aimed to verify if plant growth–promoting bacteria in termite soils also play a role in improving plant growth. To achieve our purpose, we made an effort in characterizing the bacterial genes contributing to plant-beneficial function in termite mound soils with the shotgun metagenomics method. Results from this study revealed the presence of bacterial genes involved in the production of siderophores, acetoin, trehalose, phenazine, butanediol, 4-hydroxybenzoate, chitinase, 1-aminocyclopropane-1-carboxylate (ACC) deaminase, quorum sensing molecules, and mineral phosphate solubilization. In addition, we identified bacterial genes involved in the manufacturing of catalases, peroxidases, and superoxide dismutases that confer resistance to oxidative stresses in plants. Bacterial genes responsible for glycine-betaine production and cold and heat shock tolerance which helps in withstanding abiotic stress, were also present. With these plant growth–promoting traits observed in bacteria from termite mound soils, we recommend the isolation and the use of termite mound soil bacteria both in greenhouse and field trials to further ascertain their potential in improving soil fertility and crop production.

Effects of zinc oxide nanoparticles on enzymatic and nonenzymatic antioxidant content, germination, and biochemical and ultrastructural cell characteristics of Portulaca oleracea L.

This report focuses on the application of zinc oxide nanoparticles (ZnO NPs) carrying phycomolecule ligands as a novel plant growth promoter aimed at increasing the crop productivity of purslane (<em>Portulaca oleracea</em> L.). Experiments were performed under controlled greenhouse conditions using a completely randomized design with nine replications. Purslane seeds were treated with four concentrations of ZnO NPs (0, 10, 100, and 500 mg L<sup>−1</sup>) and four concentrations of bulk ZnO (0, 10, 100, and 500 mg L<sup>−1</sup>). The ultrastructural characteristics of the leaves of the plants treated with of 500 mg L<sup>−1</sup> ZnO NPs were determined using transmission electron microscopy (TEM). The results indicated that the treatment with ZnO NPs increased the content of chlorophyll <em>a</em> and chlorophyll <em>b</em>, carotenoids, and total phenolic and flavonoid compounds significantly more than the treatment with bulk ZnO. Our findings also showed that the application of high concentrations of ZnO NPs is the most effective strategy to considerably induce the antioxidant capacity and enzymes of purslane plants. Furthermore, the seed germination percentage and sprout growth rates were significantly higher in the plants treated with 500 mg L<sup>−1</sup> of ZnO NPs (100% ±0.00), compared to the control plants (93.33% ±1.66). The TEM images revealed the concentration of ZnO NPs and cell membrane rupture, as well as a deformation in the shape of chloroplasts and a decrease in their number in the plants treated with 500 mg L<sup>−1</sup> ZnO NPs, compared to the control plants. Owing to their toxicity, high concentrations of ZnO NPs lead to oxidative stress in plants. Thus, our findings provide a new alternative strategy for increasing crop productivity, i.e., the application of ZnO NPs as a novel plant growth booster, in comparison with the bulk ZnO treatment.