The impact of copper ions on growth, lipid peroxidation, and phenolic compound accumulation and localization in lentil (Lens culinaris Medic.) seedlings

Injectable biocompatible RAFT mediated nitroxide nanogels: A robust ROS-reduction antioxidant approach

This work introduces novel nitroxide-based nanogels (NGs) crafted through controlled RAFT (Reversible Addition Fragmentation chain Transfer) polymerization, showcasing over 85% improved shelf-life compared to native superoxide dismutase (SOD) enzymes. These 30-40 nm NGs hold great promise for injectable delivery, effectively reducing foam cell formation and displaying potent antioxidant behavior against various reactive oxygen species (ROS), revolutionizing antioxidant therapy. Featuring a meticulously designed core-shell structure via precise RAFT polymerization, these NGs mimic SOD enzymatic activity with nitroxide-based antioxidants, providing unprecedented defense against ROS. Combining methacrylated 2,2,6,6-Tetramethyl-4-piperidyl methacrylate (PMA) and Glycidyl methacrylate (GMA) monomers with precisely synthesized nitroxyl radicals results in exceptional properties. Validated through comprehensive analytical methods, these NGs exhibit remarkable stability, halting foam cell formation even at high concentrations, and demonstrate notable biocompatibility. Their ability to protect low density lipoprotein (LDL) from oxidation for up to a month positions them at the forefront of combating cardiovascular diseases, especially atherosclerosis. This study pioneers injectable antioxidant therapy, offering an innovative approach to cardiovascular ailments. Targeting narrow plaques signifies a promising intervention, reshaping cardiovascular disease treatments. It highlights the potential of advanced drug delivery in biomedicine, promising more effective cardiovascular disease treatments.

Physiological and Biochemical Properties of Cotton Seedlings in Response to Cu2+ Stress

Copper(II) (Cu²⁺) is essential for plant growth and development. However, high concentrations are extremely toxic to plants. We investigated the tolerance mechanism of cotton under Cu²⁺ stress in a hybrid cotton variety (Zhongmian 63) and two parent lines with different Cu²⁺ concentrations (0, 0.2, 50, and 100 μM). The stem height, root length, and leaf area of cotton seedlings had decreased growth rates in response to increasing Cu²⁺ concentrations. Increasing Cu²⁺ concentration promoted Cu²⁺ accumulation in all three cotton genotypes' roots, stems, and leaves. However, compared with the parent lines, the roots of Zhongmian 63 were richer in Cu²⁺ and had the least amount of Cu²⁺ transported to the shoots. Moreover, excess Cu²⁺ also induced changes in cellular redox homeostasis, causing accumulation of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA). Conversely, antioxidant enzyme activity increased, while photosynthetic pigment content decreased. Our findings indicated that the hybrid cotton variety fared well under Cu²⁺ stress. This creates a theoretical foundation for the further analysis of the molecular mechanism of cotton resistance to copper and suggests the potential of the large-scale planting of Zhongmian 63 in copper-contaminated soils.

How heavy metal stress affects the growth and development of pulse crops: insights into germination and physiological processes

The current work is an extensive review addressing the effects of heavy metals in major pulse crops such as Chickpea (Cicer arietinum L.), Pea (Pisum sativum L.), Pigeonpea (Cajanus cajan L.), Mung bean (Vigna radiata L.), Black gram (Vigna mungo L.) and Lentil (Lens culinaris Medik.). Pulses are important contributors to the global food supply in the world, due to their vast beneficial properties in providing protein, nutritional value and health benefits to the human population. Several studies have reported that heavy metals are injurious to plants causing inhibition in plant germination, a decrease in the root and shoot length, reduction in respiration rate and photosynthesis. Properly disposing of heavy metal wastes has become an increasingly difficult task to solve in developed countries. Heavy metals pose one of the substantial constraints to pulse crops growth and productivity even at low concentrations. This article attempts to present the morphological, biochemical and various physiological changes induced on the pulse crops grown under various heavy metal stress such as As, Cd, Cr, Cu, Pb, and Ni.

Effects of microplastics on lentil (Lens culinaris) seed germination and seedling growth

Widespread use of plastics and mishandling has resulted in severe environmental issues affecting seed germination and seedling growth. This study investigates the effect of polyethylene microplastics (740-4990 nm PEMPs) on lentil (Lens culinaris) seed germination and seedling growth using Biospeckle Optical Coherence Tomography (bOCT), a technique that we successfully demonstrated earlier in visualizing the internal activity of plants. Lentil seeds were exposed to PEMPs bioassay for seven days with 10, 50, and 100 mg L^-1 concentrations. The average speckle contrast was calculated after 0 h, 6 h, 12 h, and 24 h of exposure, and statistically significant differences were observed just after 6 h of exposure under all the treatments. However, with conventional parameters, germination viability, germination rate, root and shoot lengths, fresh and dry seedling weights, and antioxidative enzymes, no significant effect was observed until 2 d of exposure. The results revealed that the presence of PEMPs significantly reduced the internal activity at the initial stages that could be visualized only by the use of bOCT, which has never been observed till now. Our results demonstrated for the first time the effect that microplastics indeed could hinder the internal activity during germination of the seeds, possibly resulting from the physical blockage of pores leading to stunted growth at later stages.

Cadmium phytoremediation potential of Brassica genotypes grown in Cd spiked Loamy sand soils: Accumulation and tolerance

Phytoremediation acts as an efficient methodology for management of toxic elements spiked soils. The accumulation and tolerance potential of hyper-accumulator plants for toxic elements act as an index for in-situ removal of toxic elements. Extraction of cadmium (Cd) through its accumulation in harvestable parts of plants has attracted attention as the economic and environment friendly technique. Brassica genotypes have greater potential to accumulate Cd when grown in Cd spiked soils. Therefore, for evaluation of comparative efficiency of three Brassica genotypes (B. juncea, B. campestris and B. napus) in phytoremediation of Cd spiked soils, a pot study was carried out in Cd contaminated soil with 6 levels as 0, 5, 10, 20, 40, and 80 mg kg^-1 soil. Results indicated that dry biomass production of Brassica genotypes declined with the enhanced Cd contamination in soil. The reduction in grain and shoot yield varied from 2.87 to 1.85 and 11.85 to 8.00 g pot^-1 with increased Cd contamination from 5 to 80 mg kg^-1 soil. Similarly, increased levels of Cd contamination resulted in enhanced concentration and accumulation in grains as well as shoots of all Brassica genotypes. Among Brassica genotypes, B. juncea recorded the highest production of dry biomass (12.8 g pot^-1), Cd accumulation (736.0 μg pot^-1). Also, the bioaccumulation coefficient and tolerance index indicated that B. juncea is the most tolerant genotype to Cd contamination in soil. Therefore, B. juncea could act as the most potential genotypes for decontamination of Cd spiked soils by preventing its entry into food chain.

Effects of Chromium Toxicity on Physiological Performance and Nutrient Uptake in Two Grapevine Cultivars (Vitis vinifera L.) Growing on Own Roots or Grafted onto Different Rootstocks

Chromium toxicity is considered within the most severe and dangerous nutritional disorders, and it can often be observed in crops grown in industrial areas. The present study aims to determine the effects of Cr(VI) toxicity on the growth, nutrition, and physiological performance of grapevines. In a pot hydroponic experiment, own-rooted Merlot and Cabernet Franc grapevine cultivars or cultivars grafted onto 1103P and 101-14 Mgt rootstocks were exposed to 120 μM Cr(VI). Leaf interveinal chlorosis appeared after forty-five days of treatment. Overall leaf chlorosis and brown root coloration after sixty days was reported. A significant effect on the majority of the measured parameters due to the Cr(VI) treatment was observed. Chromium stress increased the total Cr concentrations in all parts of the vines, i.e., leaves, shoots, roots, and trunks. When comparing between the studied plant sections, the roots presented the highest Cr concentrations, ranging from 396 to 868 mg kg−1 d. w., and then, in descending order, the Cr concentrations ranged from 41 to 102 mg kg−1 d. w. in the trunks, from 2.0 to 3.3 mg kg−1 d. w. in the leaves, and from 1.9 to 3.0 mg kg−1 d. w. in the shoots. Between the assessed rootstocks, 1103P was identified to be a better excluder of Cr concentration in the roots and other aerial parts of the vines. Additionally, chromium toxicity negatively affected the concentrations and compartmentalization of the most important nutrients. Leaf chlorophyll (Chl) concentration decreased down to approximately 53% after sixty days of Cr stress. Chromium toxicity significantly reduced the stem water potential (SWP), net CO2 assimilation rate (A), stomatal conductance (gs), and PSII maximum quantum yield in all the cases of grafted or own-rooted vines. At this stage, chromium stress increased the leaf total phenolic content from 46.14% in Merlot vines to 75.91% in Cabernet Franc vines.

Comparison of Myagrum perfoliatum and Sophora alopecuroides in phytoremediation of Cd- and Pb-contaminated soils: A chemical and biological investigation

Phytoremediation is one of the most cost-effective and environmentally friendly ways to reduce adverse effects of cadmium (Cd) and lead (Pb) in the environment. The present study was conducted to investigate the bioaccumulation factor (BF) and translocation factor (TF) of Cd and Pb in muskweed (Myagrum perfoliatum) and foxtail sophora (Sophora alopecuroides). The impact of contamination on some growth responses of plants and soil biological indicators was also evaluated. A non-contaminated soil sample was divided into several subsamples: one subsample was left as control (without contamination) and the others were separately contaminated with three levels of Cd (3, 5, and 10 mg kg^-1) and Pb (100, 300, and 600 mg kg^-1). Pot experiments were performed under greenhouse conditions. The BF values of Cd were greater than 1 at all contamination levels indicating the potential of muskweed and foxtail sophora for the uptake and phytostabilization of Cd. The only TF > 1 was obtained for Cd in muskweed grown at the highest Cd contamination level. The TF values of Pb were much lower than those obtained for Cd indicating that Cd was more translocated from root to aerial parts of muskweed and foxtail sophora compared to Pb. The highest contamination levels of Cd and Pb did not significantly affect growth responses of muskweed and foxtail sophora. Furthermore, the cultivation of muskweed and foxtail sophora reduced the impact of Cd and Pb contamination on biological indicators including carbon mineralization ratio (CMR), substrate-induced respiration (SIR), microbial biomass carbon (MBC), and metabolic quotient (qCO₂).

Heavy metal induced stress on wheat: phytotoxicity and microbiological management

Among many soil problems, heavy metal accumulation is one of the major agronomic challenges that has seriously threatened food safety. Due to these problems, soil biologists/agronomists in recent times have also raised concerns over heavy metal pollution, which indeed are unpleasantly affecting agro-ecosystems and crop production. The toxic heavy metals once deposited beyond certain permissible limits, obnoxiously affect the density, composition and physiological activities of microbiota, dynamics and fertility of soil leading eventually to reduction in wheat production and via food chain, human and animal health. Therefore, the metal induced phytotoxicity problems warrant urgent and immediate attention so that the physiological activities of microbes, nutrient pool of soils and concurrently the production of wheat are preserved and maintained in a constantly deteriorating environment. To mitigate the magnitude of metal induced changes, certain microorganisms have been identified, especially those belonging to the plant growth promoting rhizobacteria (PGPR) group endowed with the distinctive property of heavy metal tolerance and exhibiting unique plant growth promoting potentials. When applied, such metal-tolerant PGPR have shown variable positive impact on wheat production, even in soils contaminated with metals, by supplying macro and micro nutrients and secreting active biomolecules like EPS, melanins and metallothionein (MTs). Despite some reports here and there, the phytotoxicity of metals to wheat and how wheat production in metal-stressed soil can be enhanced is poorly explained. Thus, an attempt is made in this review to better understand the mechanistic basis of metal toxicity to wheat, and how such phytotoxicity can be mitigated by incorporating microbiological remediation strategies in wheat cultivation practices. The information provided here is likely to benefit wheat growers and consequently optimize wheat production inexpensively under stressed soils.

Among many soil problems, heavy metal accumulation is one of the major agronomic challenges that has seriously threatened food safety.

Fe0 nanoparticles improve physiological and antioxidative attributes of sunflower (Helianthus annuus) plants grown in soil spiked with hexavalent chromium

Contamination of agricultural land by chromium (Cr) can inhibit physiological and biochemical processes in plants, leading to reduced crop productivity and food/feed safety. Owing to their fine size, large surface area, and high adsorption affinity for metals, nanomaterials have shown a potential for phytoremediation of heavy metal-contaminated soils. Nanomaterials enhance fitness of plants under metal stress through their modifying effects on plant physiology and biochemistry. The aim of this study was to assess the performance of sunflower (Helianthus annuus) plants grown in soil spiked with hexavalent chromium (Cr IV; 0, 75 and 150 ppm) and the potential role of nano-zerovalent iron (Fe0 nanoparticles; 0, 1 and 2%) to ameliorate Cr toxicity. Results revealed that the Cr uptake decreased by increasing the concentration of Fe0 nanoparticles, causing a significant enhancement in plant morphological and physiological attributes. Treatment with Fe0 nanoparticles reduced bioaccumulation factor (BAF) (in both root and shoot tissues) and translocation factor (TF); however, the magnitude of BAF and TF decreased significantly by increasing the level of Cr(VI). Chromium stress increased the activities of antioxidant enzymes, which further increased by Fe0 nanoparticle application, resulting in improved growth traits. A significant positive correlation was found between growth, BAF and TF of seedlings treated with Fe0 nanoparticles (both 1 and 2%) upon Cr exposure (75 and 150 ppm). The results demonstrated the potential of Fe0 nanoparticles to improve performance of sunflower plants under Cr toxicity through reducing their Cr uptake, which was accompanied by enhanced activity of detoxification enzymes (SOD, CAT, POX, and APX) in cells.

Reactive oxygen species, auxin and nitric oxide in metal-stressed roots: toxicity or defence

The presented review is a summary on the current knowledge about metal induced stress response in plants, focusing on the roles of reactive oxygen species, auxin and nitric oxide in roots. The article focuses mainly on the difference between defence and toxicity symptoms of roots during metal-induced stress. Nowadays, pollution of soils by heavy metals is a rapidly growing issue, which affects agriculture and human health. In order to deal with these problems, we must first understand the basic mechanisms and responses to environmental conditions in plants growing under such conditions. Studies so far show somewhat conflicting data, interpreting the same stress responses as both symptoms of defence and toxicity. Therefore, the aim of this review is to give a report about current knowledge of heavy metal-induced stress research, and also to differentiate between toxicity and defence, and outline the challenges of research, focusing on reactive oxygen and nitrogen species, auxin, and the interplay among them. There are still remaining questions on how reactive oxygen and nitrogen species, as well as auxin, can activate either symptoms of toxicity or defence, and adaptation responses.

The combined and single effect of salinity and copper stress on growth and quality of Mentha spicata plants

Copper is essential for plant growth, but in excess may cause adverse effects on plant physiology. Harmful effects are also caused by plant exposure to salinity (NaCl) due to the excessive use of fertilizers, soil degradation and/or the quality of the water used for irrigation. The impact of single and combined salinity (Sal) and copper (Cu) stress on spearmint metabolism were studied in hydroponics. Spearmint plants (Mentha spicata L.) were subjected to salinity stress (150 mM NaCl) and/or excessive Cu concentration (60 μM Cu) via the nutrient solution. Not only Sal and Cu, but also their combination suppressed plant growth by decreasing plant biomass, root fresh weight and plant height. Chlorophyll content decreased mainly for the combined stress treatment (Sal + Cu). Polyphenols and antioxidants (FRAP, DPPH, ABTS) increased in single stress treatments (Sal or Cu), but decreased in the combined stress (Sal + Cu). The application of Sal or Cu stress decreased Zn, N and K (leaves), K, Ca, P and Mg (roots) content. Copper application increased Ca and Mg in leaves. In conclusion, salinity stress and Cu exposure may change the primary metabolic pathways in favor of major volatile oil components biosynthesis, resulting in significant changes of essential oil yield and composition.

Effects of lead and cadmium on photosynthesis in Amaranthus spinosus and assessment of phytoremediation potential

This study assessed the effects of Pb (0, 200, 500, 1000 mg kg^-1) and Cd (0, 5, 15, 30, 50 mg kg^-1) on photosynthesis in Amaranthus spinosus (A. spinosus), as well as the potential for phytoremediation by pot-culture experiment. Exposure to Pb/Cd produced a concentration-dependent decrease in biomass and all photosynthesis parameters, except for non-photochemical quenching, which increased with the metal concentration. The metals accumulated more in roots compared to shoots. The bioconcentration factor (BCF) of Pb was <1 in shoots at all Pb levels, whereas the BCF was <1 in roots at all but the lowest concentration of Pb. Roots extracted Cd from soil at all treatments. The translocation factor of Cd was larger than that of Pb suggesting that Cd is more mobile than Pb in A. spinosus. Amaranthus spinosus displays a high tolerance for both Pb and Cd with regards to growth and photochemical efficiency, but it is more sensitive to Cd than Pb. Amaranthus spinosus accumulates Pb and Cd primarily in the roots and Cd is more bioconcentrated and translocated in comparison to Pb. This investigation shows that A. spinosus has good potential for phytoremediation of soils contaminated by low levels of Cd and Pb.

A new perspective to aberrations caused by barium and vanadium ions on Lens culinaris Medik

This study investigates aberrations caused by barium and vanadium on meristematic cells of Lens culinaris Medik. Barium and vanadium ions at various concentrations (0.05 M, 0.1 M, 0.25 M, 0.5 M, and 1.0 M) were exposed to the seeds of the plant at fixed time interval (12 h). After seedlings, with a microscopic examination images were captured about the root tips. Those images showed that several abnormalities occurred on the plant such as chromosome breakings, chromosome dispersion, bridge chromosome, chromosome adherence, ring chromosome. Variety and number of abnormalities were counted and compared to each other statistically. The results show an increase in abnormalities caused by for both ions with increasing treatment time. Chromosome adherence and chromosome breaking have reverse relationship in which number of occurrence for one of them decreases with increase on other one. Fish bone and chromosome adherence have a positive relationship in which number of one increases with the raise in other's number. Exposed metals have caused formation of ligands with proteins which can prevent the persistence of metal ions in DNA protein cross-links that are involved in DNA formation process.

Protective role of exogenous phytohormones on redox status in pea seedlings under copper stress

The present work aims to provide insight on the role of phytohormone application in developing efficient practical defense strategies to improve plants tolerance under heavy metal contamination. For this purpose, pea (Pisum sativum L.) seeds were germinated in an aqueous solution of 200μM CuCl2 up to the 3rd day and then continued to germinate in the presence of distilled water (stress cessation) or were subjected to following combinations: Cu+1μM IAA and Cu+1μM GA3 for 3 additional days. The results showed that copper excess induced oxidative stress in germinating seeds, which resulted in changes of the redox state of glutathione and cysteine, and proteomics revealed Cu-induced modifications of thiols (SH) and carbonyls (CO) (indicators of protein oxidation). However, application of IAA or GA3 in the germination medium after 3days of Cu exposure alleviated toxicity on seedlings, despite the persistence of Cu up to 6th day. This improving effect seems to be mediated by a cell Cu accumulation decrease and a protein reduced status recovery, since phytohormones modulate thioredoxin/ferredoxin systems in favor of protecting proteins against oxidation. In addition, an IAA and GA3 protective effect was evidenced by a cellular homeostasis amelioration resulting from the balance conservation between the regeneration and consumption processes of glutathione and cysteine reduced forms. The exogenous effectors also induced modifications of profiles of SH and CO, suggesting changes in the regulation and expression of proteins that could be involved in defense mechanism against Cu stress.

Protective role of selenium against chromium stress involving metabolites and essential elements in Brassica juncea L. seedlings

The present study aimed at the potential role of selenium in providing protection to plants subjected to chromium toxicity. The study was carried out on 15-day-old seedlings of Brassica juncea raised in the solutions of Cr (300 µM) and Se (2, 4 and 6 µM), both alone and in combinations under controlled laboratory environment. The effects were studied on growth, plant metabolites (involved in osmotic homeostasis and stress protection), and essential elements. The results showed that the exposure of B. juncea seedlings to 300 µM Cr led to an increase in the contents of total sugars, reducing sugars, non-reducing sugars, total phenols and flavonoids. However, a significant decline in growth characteristics, the contents of proteins and free amino acids was observed. The essential elements (Na, K, Ca, Mg, C, H, N) also decreased in response to Cr. Se application in binary combinations, on the other hand, aided in improving seed germination (19%), root (88.3%) and shoot (18.2%) lengths. It also helped to increase the contents of sugars [total (16.3%), reducing (21.6%) and non-reducing (15.2%)], phenols (36.7%) and flavonoids (27.4%), thereby aiding in alleviating the phytotoxicity of Cr. The profiling of polyphenols and amino acids, and histological study of phenols supported the above results. The contents of essential elements also showed a significant increase, while Cr uptake was observed to decline by Se supplementation. The observations from the present study indicate that Se has the ability to influence primary and secondary metabolism, improve mineral nutrition and reduce Cr uptake in B. juncea seedlings to combat the Cr phytotoxicity and enhance the tolerance against stress.

Redox biology response in germinating Phaseolus vulgaris seeds exposed to copper: Evidence for differential redox buffering in seedlings and cotyledon

In agriculture, heavy metal contamination of soil interferes with processes associated with plant growth, development and productivity. Here, we describe oxidative and redox changes, and deleterious injury within cotyledons and seedlings caused by exposure of germinating (Phaseolus vulgaris L. var. soisson nain hâtif) seeds to copper (Cu). Cu induced a marked delay in seedling growth, and was associated with biochemical disturbances in terms of intracellular oxidative status, redox regulation and energy metabolism. In response to these alterations, modulation of activities of antioxidant proteins (thioredoxin and glutathione reductase, peroxiredoxin) occurred, thus preventing oxidative damage. In addition, oxidative modification of proteins was detected in both cotyledons and seedlings by one- and two-dimensional electrophoresis. These modified proteins may play roles in redox buffering. The changes in activities of redox proteins underline their fundamental roles in controlling redox homeostasis. However, observed differential redox responses in cotyledon and seedling tissues showed a major capacity of the seedlings' redox systems to protect the reduced status of protein thiols, thus suggesting quantitatively greater antioxidant protection of proteins in seedlings compared to cotyledon. To our knowledge, this is the first comprehensive redox biology investigation of the effect of Cu on seed germination.

Biotoxic impact of heavy metals on growth, oxidative stress and morphological changes in root structure of wheat (Triticum aestivum L.) and stress alleviation by Pseudomonas aeruginosa strain CPSB1

Rapid industrialization and uncontrolled metal discharge into environment is a global concern for crop production. Metal tolerant bacterium isolated from chilli rhizosphere was identified as Pseudomonas aeruginosa by 16S rDNA sequence analysis. Pseudomonas aeruginosa tolerated high concentrations of Cu (1400 μg ml^-1), Cd (1000 μg ml^-1) and Cr (1000 μg ml^-1). Pseudomonas aeruginosa CPSB1 produced multiple plant growth promoting biomolecules in the presence and absence of metals. Strain CPSB1 solubilized P at 400 μg ml^-1 of Cd, Cr and Cu. The strain was positive for indole-3-acetic acid (IAA), siderophores, hydrogen cyanide (HCN), ammonia (NH₃) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase when grown with/without metals. The phytotoxic effects on wheat increased with increasing Cd, Cr and Cu rates. The P. aeruginosa CPSB1 inoculated wheat in contrast had better growth and yields under Cu, Cd and Cr stress. The root dry biomass of inoculated plants was enhanced by 44, 28 and 48% at 2007 mg Cu kg^-1, 36 mg Cd kg^-1 and 204 mg Cr kg^-1, respectively. The bioinoculant enhanced number of spikes, grain and straw yields by 25, 17 and 12%, respectively. Pseudomonas aeruginosa CPSB1 significantly declined the levels of catalase (CAT), glutathione reductase (GR) and superoxide dismutase SOD), proline and malondialdehyde (MDA), and reduced metal uptake by wheat. The study demonstrated that P. aeruginosa CPSB1 possessed plant growth promoting potentials, showed metal tolerance capability and had ability to counteract deleterious metal impacts. Due to these, P. aeruginosa CPSB1 could be used as bioinoculant for enhancing wheat production even in metal contaminated soils.

Copper and nickel co-treatment alters metal uptake and stress parameters of Salix purpurea×viminalis

Simultaneous treatment of Salix purpurea×viminalis with copper (Cu²⁺) and nickel (Ni²⁺) altered metal phytoextraction rates in favor of leaves. Still, metal translocation patters remained unaffected (roots≈rods>>leaves≥shoots), reaching ∼20 and 14.5mgkg^-1 dry weight in roots for Cu and Ni, respectively. Biometric parameters revealed overall growth inhibition correlated with Cu content in leaves, thus proving its negative effect on photosynthesis. Metal toxicity was strongly affirmed in the case of roots (∼90% loss of root biomass at 3mM), rather than in the above-ground organs. Plant treatment accelerated the accumulation of soluble carbohydrates, phenolics including salicylic acid and glutathione in Salix leaves. However, significant differences in plant reactions to the applied metals were noted. Metal accumulation in leaves was correlated with soluble sugars and elevated glutathione, and also with total phenolics content, in the case of Cu and Ni, respectively. Glutathione synthesis was induced by both metals, and correlated with salicylic acid in leaves of Ni-treated plants.

Terpenoid trans-caryophyllene inhibits weed germination and induces plant water status alteration and oxidative damage in adult Arabidopsis

trans-Caryophyllene (TC) is a sesquiterpene commonly found as volatile component in many different aromatic plants. Although the phytotoxic effects of trans-caryophyllene on seedling growth are relatively explored, not many information is available regarding the phytotoxicity of this sesquiterpenes on weed germination and on adult plants. The phytotoxic potential of TC was assayed in vitro on weed germination and seedling growth to validate its phytotoxic potential on weed species. Moreover, it was assayed on the metabolism of Arabidopsis thaliana adult plants, through two different application ways, spraying and watering, in order to establish the primary affected organ and to deal with the unknown mobility of the compound. The results clearly indicated that TC inhibited both seed germination and root growth, as demonstrated by comparison of the ED50 values. Moreover, although trans-caryophyllene-sprayed adult Arabidopsis plants did not show any effect, trans-caryophyllene-watered plants became strongly affected. The results suggested that root uptake was a key step for the effectiveness of this natural compound and its phytotoxicity on adult plants was mainly due to the alteration of plant water status accompanied by oxidative damage.

Copper-resistant bacteria reduces oxidative stress and uptake of copper in lentil plants: potential for bacterial bioremediation

For effective microbe-assisted bioremediation, metal-resistant plant growth-promoting bacteria (PGPB) must facilitate plant growth by restricting excess metal uptake in plants, leading to prevent its bio-amplification in the ecosystem. The aims of our study were to isolate and characterize copper (Cu)-resistant PGPB from waste water receiving contaminated soil. In addition, we investigated the phytotoxic effect of copper on the lentil plants inoculated with copper-resistant bacteria Providencia vermicola, grown in copper-contaminated soil. Copper-resistant P. vermicola showed multiple plant growth promoting characteristics, when used as a seed inoculant. It protected the lentil plants from copper toxicity with a considerable increase in root and shoot length, plant dry weight and leaf area. A notable increase in different gas exchange characteristics such as A, E, C i , g s , and A/E, as well as increase in N and P accumulation were also recorded in inoculated plants as compared to un-inoculated copper stressed plants. In addition, leaf chlorophyll content, root nodulation, number of pods, 1,000 seed weight were also higher in inoculated plants as compared with non-inoculated ones. Anti-oxidative defense mechanism improved significantly via elevated expression of reactive oxygen species -scavenging enzymes including ascorbate peroxidase, superoxide dismutase, catalase, and guaiacol peroxidase with alternate decrease in malondialdehyde and H2O2 contents, reduced electrolyte leakage, proline, and total phenolic contents suggesting that inoculation of P. vermicola triggered heavy metals stress-related defense pathways under copper stress. Overall, the results demonstrated that the P. vermicola seed inoculation confer heavy metal stress tolerance in lentil plant which can be used as a potent biotechnological tool to cope with the problems of copper pollution in crop plants for better yield.

Role of the ubiquitin-proteasome pathway and some peptidases during seed germination and copper stress in bean cotyledons

The role of the ubiquitin (Ub)-proteasome pathway and some endo- and aminopeptidases (EPs and APs, respectively) was studied in cotyledons of germinating bean seeds (Phaseolus vulgaris L.). The Ub system appeared to be important both in the early (3 days) and late (9 days) phases of germination. In the presence of copper, an increase in protein carbonylation and a decrease in reduced -SH pool occurred, indicating protein damage. This was associated with an enhancement in accumulation of malondialdehyde, a major product of lipid peroxidation, and an increase in content of hydrogen peroxide (H2O2), showing oxidative stress generation. Moreover, copper induced inactivation of the Ub-proteasome (EC 3.4.25) pathway and inhibition of leucine and proline aminopeptidase activities (EC 3.4.11.1 and EC 3.4.11.5, respectively), thus limiting their role in modulating essential metabolic processes, such as the removal of regulatory and oxidatively-damaged proteins. By contrast, total trypsin and chymotrypsin-like activities (EC 3.4.21.4 and EC 3.4.21.1, respectively) increased after copper exposure, in parallel with a decrease in their inhibitor capacities (i.e. trypsin inhibitor and chymotrypsin inhibitor activity), suggesting that these endoproteases are part of the protective mechanisms against copper stress.

Altered physiology, cell structure, and gene expression of Theobroma cacao seedlings subjected to Cu toxicity

Seedlings of Theobroma cacao CCN 51 genotype were grown under greenhouse conditions and exposed to increasing concentrations of Cu (0.005, 1, 2, 4, 8, 16, and 32 mg Cu L(-1)) in nutrient solution. When doses were equal or higher than 8 mg Cu L(-1), after 24 h of treatment application, leaf gas exchange was highly affected and changes in chloroplasts thylakoids of leaf mesophyll cells and plasmolysis of cells from the root cortical region were observed. In addition, cell membranes of roots and leaves were damaged. In leaves, 96 h after treatments started, increases in the percentage of electrolyte leakage through membranes were observed with increases of Cu in the nutrient solution. Moreover, there was an increase in the concentration of thiobarbituric acid-reactive substances in roots due to lipid peroxidation of membranes. Chemical analysis showed that increases in Cu concentrations in vegetative organs of T. cacao increased with the increase of the metal in the nutrient solution, but there was a greater accumulation of Cu in roots than in shoots. The excess of Cu interfered in the levels of Mn, Zn, Fe, Mg, K, and Ca in different organs of T. cacao. Analysis of gene expression via RTq-PCR showed increased levels of MT2b, SODCyt, and PER-1 expression in roots and of MT2b, PSBA, PSBO, SODCyt, and SODChI in leaves. Hence, it was concluded that Cu in nutrient solution at doses equal or above 8 mg L(-1) significantly affected leaf gas exchange, cell ultrastructure, and transport of mineral nutrients in seedlings of this T. cacao genotype.

Could an abandoned mercury mine area be cropped?

The Almadén area (Spain) is known for its high natural mercury background as well as for the anthropogenic impact due to mining activities. After the end of these activities, appropriate alternative use of the soil has to be found, and agricultural activities stand out as an environmentally-friendly and potentially profitable alternative, giving to the soil a sustainable use without risks for human or animal health according to current legislation. Experiments performed at different scales (involving hydroponics, growth in pots and lysimeters) allow recommendations to be made regarding the adequacy of cultivation of different crops for animal or human consumption before they are sown in the field. Regarding crops for animal feeding, mercury accumulation in vegetative organs represents a higher potential risk for animals. Nevertheless, seeds and fruits can be used, both for human and animal consumption. Finally, this work will lead the way to obtain a scientific basis for elaborating a list of recommendations on sustainable and safe alternative land use, according to current international legislation.

Tissue and method specificities of phenylalanine ammonia-lyase assay

A large number of studies have estimated phenylalanine ammonia-lyase (PAL) activity because it strongly reacts to various stimuli. Activity of this enzyme has been assayed mainly by means of spectrophotometry, but the precision of this method is poorly known. We compared assays of PAL activity using spectrophotometry and high performance liquid chromatography (HPLC) in two species (Matricaria chamomilla and Arabidopsis thaliana). Additionally, copper-exposed M. chamomilla plants and buffer with additive were also tested. Our data indicate that spectrophotometry both overestimates (leaves of M. chamomilla) and underestimates (leaves and roots of A. thaliana) PAL activity in comparison with HPLC, suggesting interference of UV-absorbing metabolites. HPLC also showed more accurate detection of cinnamic acid in Cu-exposed chamomile roots. Addition of dithiothreitol to the extraction buffer enhanced PAL activity but reduced proteins, indicating an artificial negative effect. A comparison of PAL activity in selected species is also provided.

Modulation of copper uptake and toxicity by abiotic stresses in Matricaria chamomilla plants

The impact of salinity (S) or nitrogen deficiency (-N) on copper (Cu) uptake and changes to metabolism were studied in the combined treatments after 7 days of exposure. S suppressed growth, water content, soluble proteins, and reducing sugars more negatively than -N. ROS (hydrogen peroxide and superoxide) were differentially but relatively slightly affected while peroxidase activities were strongly elevated mainly in Cu+NaCl variant. Total soluble phenols and individual phenolic acids (free and cell wall-bound fraction) were accumulated the most in Cu-N while, among free amino acids, proline sharply increased in Cu+NaCl; this suggests a compensatory mechanism between the syntheses of antioxidants aimed to maintain antioxidative protection because numerous root phenolic acids were even depressed by S. Salinity also suppressed accumulation of coumarin herniarin, but its glucosidic precursors ((Z)- and (E)-2-ß-D-glucopyranosyloxy-4-methoxycinnamic acids) increased. Activities of selected phenolic enzymes were rather suppressed by S after a given exposure period while lignin content increased, suggesting different time dynamics if S and -N variants are compared. Selected mineral nutrients (K, Fe, and partially Mg) were more reduced by S than by -N. Shoot and root Cu amounts were depressed by -N but elevated by S. Significance and possible role of observed metabolic changes in relation to Cu accumulation are discussed.

Changes in the nature of phenolic deposits after re-warming as a result of melatonin pre-sowing treatment of Vigna radiata seeds

Changes in phenolics (PhC - phenolic compounds) measured as UV-absorbing compounds (UVAC) and their localization as well as growth, lipid peroxidation (TBARS level) and proline (Pro) level in three-day-old roots of seedlings (T(o) stage) obtained from hydroprimed (H) and hydroprimed with melatonin (H-MEL) seeds after 2 days of chilling (5°C) and 2 days of re-warming were examined. H and H-MEL resulted in inhibition of root growth under optimal conditions, but after re-warming, a positive effect of MEL was noted. The results also showed a positive MEL impact on TBARS level already after chilling and especially after re-warming. Exposure of Vigna radiata seedlings to chilling caused a significant increase in Pro level, especially in H-MEL roots, but after re-warming it drastically decreased. Under chilling stress, accumulation of UVAC also decreased. However, after re-warming it returned to the level observed in the roots grown constantly at 25°C. Even if after re-warming of V. radiata seedlings only slight accumulation of total PhC was observed, phenolic deposits accumulating in the vacuoles of H-MEL roots were completely different from those in the vacuoles of the control and H roots. H-MEL application to the seeds resulted in a significant increase in small granular composite materials, while in the control and H roots, large oval deposits prevailed. Taken together, it is probable that all of these differences were connected with positive effects of MEL on chilled V. radiata seedlings after re-warming.

Significance of phenols in cadmium and nickel uptake

The effects of 2-aminoindane-2-phosphonic acid (AIP), a potent phenylalanine ammonia-lyase (PAL) inhibitor, on the accumulation of cadmium and nickel in chamomile (Matricaria chamomilla) were examined in this study. In vitro assay of AIP effect showed a 90% reduction in PAL activity. In plants cultured for 7 days in Cd or Ni solutions with AIP, PAL activity was higher in both shoots and roots (in comparison with metals without AIP), and was correlated with changes in free phenylalanine content. Individual amino acids were both positively and negatively affected by AIP, with the accumulation of tyrosine and proline showing increases in some variants. Contents of soluble phenols and flavonoids were not considerably affected, while amounts of coumarin-related compounds, cell wall-bound phenols and phenolic acids were substantially reduced in AIP-treated variants. Lignin accumulation decreased in controls and increased in Cd variants in response to AIP. Shoot Cd content was depleted, but shoot Ni was elevated by AIP. Total root content of Cd and Ni decreased in +AIP variants. AIP also caused more expressive changes in hydrogen peroxide and superoxide content in Cd than in Ni variants. Our results indicate that phenols have important roles in the uptake of Cd and Ni. The present findings are discussed in the context of available data regarding AIP's effect on phenols.

Copper uptake is differentially modulated by phenylalanine ammonia-lyase inhibition in diploid and tetraploid chamomile

The effect of phenylalanine ammonia-lyase (PAL) inhibition by 2-aminoindane-2-phosphonic acid (AIP) in copper-exposed diploid and tetraploid chamomile (Matricaria chamomilla ) roots has been studied in a short-term experiment (24 h). Cu evoked stronger induction of PAL activity and accumulation of soluble phenols, flavonols (quercetin and kaempferol), and lignin in diploid plants, whereas AlCl3-reactive flavonoids and phenolic acids did not differ with respect to ploidy. Amounts of hydrogen peroxide and superoxide also preferentially increased in diploid. Surprisingly, PAL activity was restored in both +AIP cultivars, being inversely correlated with the accumulation of free phenylalanine. Notwithstanding this, total soluble phenols and flavonols were more depleted in Cu+AIP diploid roots. Soluble proteins decreased in response to Cu, and AIP had no effect. Among free amino acids, proline increased more visibly in Cu+AIP diploid, suggesting that this could be a protective mechanism in conditions with depleted content of phenols. Decrease in potassium content was ploidy-independent, calcium increased in all Cu variants, and Fe increased in Cu-exposed tetraploid. Shoot Cu content did not differ in Cu-exposed cultivars, but diploid roots contained more Cu. AIP decreased root Cu but increased shoot Cu amounts in diploid, whereas tetraploid plants did not exhibit similar responses. These data indicate that inhibition of root phenolic metabolism by AIP was effective enough, allowing Cu to accumulate in diploid shoots. The present findings are discussed in the context of available data about AIP effects and with respect to the role of phenols in metal uptake.