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1.
Chemosphere ; : 132471, 2021 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-34626653

RESUMO

Present study showed the successful application of the modified hydrothermal method for synthesizing the zinc oxide nanoparticles (ZnO-NPs) efficiently. Well as-synthesized ZnO-NPs are analyzed for various techniques viz., X-ray diffraction (XRD), SEM micrographs, EDAX/Mapping pattern, Raman Spectroscopy Pattern, UV, Photoluminescence (PL) and X-ray photoemission spectroscopy (XPS) analysis. All these measurements showed that ZnO-NPs are highly pure with no internal defects, and can be potentially used in the plant applications. Hence, we further determined the effect of these nanoparticles and melatonin for the modulation of the As tolerance in soybean plants by examining the various growth attributes and metabolic parameters. Our results demonstrated that As-stress inhibited growth (∼34%), photosynthesis-related parameters (∼18-28%) and resulting ROS accumulation; however, all these attributes are substantially reversed by the ZnO-NPs and melatonin treatments. Moreover, the As stress induced malondialdehyde (MDA; 71%) and hydrogen peroxide (H2O2; 82%) are partially reversed by the ZnO-NPs and melatonin in the As-stressed plants. This might have resulted due to the ZnO-NPs and melatonin induced activities of the antioxidants plant defense. Overall, the ZnO-NPs and melatonin supplementation separately and in combination positively regulated the As tolerance in soybean; however, the effect of the combined application on the As tolerance was more profound relative to the individual application. These results suggested the synergetic effect of the ZnO-NPs and melatonin on the As tolerance in soybean. However, the in-depth mechanism underlying the defense crosstalk between the ZnO-NPs and melatonin needs to be further explored.

2.
Sci Rep ; 11(1): 19768, 2021 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-34611203

RESUMO

Cadmium stress is one of the chief environmental cues that can substantially reduce plant growth. In the present research, we studied the effect of jasmonic acid (JA) and gibberellic acid (GA3) applied individually and/or in combination to chickpea (Cicer arietinum) plants exposed to 150 µM cadmium sulphate. Cadmium stress resulted in reduced plant growth and pigment contents. Moreover, chickpea plants under cadmium contamination displayed higher levels of electrolytic leakage, H2O2, and malonaldehyde, as well as lower relative water content. Plants primed with JA (1 nM) and those foliar-fed with GA3 (10-6 M) showed improved metal tolerance by reducing the accumulation of reactive oxygen species, malonaldehyde and electrolytic leakage, and increasing relative water content. . Osmoprotectants like proline and glycinebetaine increased under cadmium contamination. Additionally, the enzymatic activities and non-enzymatic antioxidant levels increased markedly under Cd stress, but application of JA as well as of GA3 further improved these attributes. Enzymes pertaining to the ascorbate glutathione and glyoxylase systems increased significantly when the chickpea plants were exposed to Cd. However, JA and GA3 applied singly or in combination showed improved enzymatic activities as well as nutrient uptake, whereas they reduced the metal accumulation in chickpea plants. Taken together, our findings demonstrated that JA and GA3 are suitable agents for regulating Cd stress resistance in chickpea plants.

3.
J Environ Manage ; 301: 113769, 2021 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-34600426

RESUMO

Forests have been undergoing through immense pressure due to the factors like human activities; procurement of forest products and climate change which is a major factor influencing this pressure buildup on forests. Climate change and temperature increase caused by anthropogenic activities have notably affected forests and wildlife on a global scale. High temperature increases the soil-water evaporation, resulting in drier soils, and water loss in forest flora. The incidence of forest fires has doubled since 1984 and these are linked to global warming. Drought influences fuel moisture by bringing about physiological changes in forest vegetation leading to forest fires. Forest resilience is hampered because of temperature and drought stress at the developing stage of plant's life cycle leading to the shift in plant species in those areas. Forest fire incidences can be managed with proper management strategies such as sustainable, community and urban forest management. A careful monitoring of stress precursors, subsistence uses of forests, ecological education and planting of near native and new indigenous plant species are the tools that can aid in efficient forest management.

4.
Plant Physiol Biochem ; 167: 723-737, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34500197

RESUMO

It was aimed to assess that up to what extent endogenous nitric oxide (NO) and its sources are involved in glutathione (GSH)-mediated tolerance of maize plants to cadmium (Cd) stress. The Cd-stressed maize plants were sprayed with or without GSH (1.0 mM) once every week for two weeks. Before initiating the stress treatment, the Cd-stressed plants sprayed with GSH were supplied with or without 0.1 mM, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO; a NO scavenger) for two weeks or with 0.1 mM sodium tungstate (ST; a nitrate reductase inhibitor), or 0.1 mM NG-nitro-L-arginine methyl ester hydrochloride (L-NAME). Cadmium stress suppressed the activities of dehydroascorbate reductase, monodehydroascorbate reductase, and glyoxalase II, while increased leaf NO, Cadmium content, proline, oxidative stress, the activities of glutathione reductase, ascorbate peroxidase, the key enzymes of oxidative defense system, glyoxalase I, NR and NOS. GSH reduced oxidative stress and tissue Cd2+ content, but it improved growth, altered water relations, and additionally increased proline levels, activities of the AsA-GSH cycle, key enzymatic antioxidants, glyoxalase I and II, NR and NOS as well as NO content. The cPTIO and ST supplementation abolished the beneficial effects of GSH by reducing the activities of NO and NR. However, L-NAME did not retreat the favorable effects of GSH, although it reduced the NOS activity without eliminating NO content, suggesting that NR might be a prospective source of NO generated by GSH in Cd-stressed plants, which in turn accelerated the activities of antioxidant enzymes.

5.
Environ Pollut ; 290: 118029, 2021 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-34474375

RESUMO

Arsenic (As) is recognized as a toxic metalloid and a severe threat to biodiversity due to its contamination. Soil and groundwater contamination with this metalloid has become a major concern. Large fractions of cultivable lands are becoming infertile gradually due to the irrigation of As contaminated water released from various sources. The toxicity of As causes the generation of free radicals, which are harmful to cellular metabolism and functions of plants. It alters the growth, metabolic, physiological, and molecular functions of the plants due to oxidative burst. Plants employ different signaling mechanisms to face the As toxicity like phosphate cascade, MAPK (Mitogen-Activated Protein Kinase), Ca-calmodulin, hormones, and ROS-signaling. The toxicity of As may significantly be reduced through various remediation techniques. Among them, the microbial-assisted remediation technique is cost-effective and eco-friendly. It breaks down the metalloid into less harmful species through various processes viz. biovolatilization, biomethylation, and transformation. Moreover, the adaptation strategies towards As toxicity are vacuolar sequestration, involvement of plant defense mechanism, and restricting its uptake from plant roots to above-ground parts. The speciation, uptake, transport, metabolism, ion dynamics, signaling pathways, crosstalk with phytohormones and gaseous molecules, as well as harmful impacts of the As on physiological processes, overall development of plants and remediation techniques are summarized in this review.

6.
Ecotoxicol Environ Saf ; 223: 112519, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34364122

RESUMO

Drought stress is reducing the production of crops globally. This research was designed to evaluate the role of titanium dioxide (TiO2 NPs) nanoparticles and calcium phosphate on wheat facing drought stress. TiO2 NPs were prepared by green synthesis and their characterization (by UV-visible spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX)) was also done. The results showed that TiO2 NPs worked efficiently and improved plant growth under drought. However, the best results were obtained from combined applications of 40 ppm TiO2 NPs and 40 ppm calcium phosphate on plants. They increased root length (33%), shoot length (53%), fresh weight (48%), and dry weight (44%) of wheat as compared to control. The physiological parameters including chlorophyll content, relative water content, membrane stability index, and osmolyte content (proline and sugar) were also improved. The increase in superoxide dismutase, peroxidase and, catalase activity by the combined application of TiO2 NPs and calcium phosphate was 83% and 78%, 74% and 52%, 81%, and 67% in Pakistan-13 and Zincol-16 respectively, as compared to untreated drought exposed plants. They also enhanced the nutrients uptake (including potassium, phosphorus, and nitrogen) that ultimately improved plant biomass. They also maintained the level of growth hormones in plants. These hormones regulate cellular processes and are responsible for germination, development, and plant reaction in drought stress. The increase in the yield was also significant, hence it is recommended that the 40 ppm concentration of TiO2 NPs along with calcium phosphate improves the productivity of wheat under drought stress.


Assuntos
Nanopartículas , Triticum , Fosfatos de Cálcio , Secas , Nanopartículas/toxicidade , Titânio/toxicidade
8.
J Hazard Mater ; 417: 126050, 2021 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-34229383

RESUMO

Arsenic, a group 1 carcinogen for humans, is abundant as compared to other trace elements in the environment and is present mainly in the Earth's crust and soil. The arsenic distributions in different geographical regions are dependent on their geological histories. Anthropogenic activities also contribute significantly to arsenic release into the environment. Arsenic presents several complications to humans, animals, and plants. The physiology of plants and their growth and development are affected by arsenic. Arsenic is known to cause cancer and several types of organ toxicity, such as cardiotoxicity, nephrotoxicity, and hepatotoxicity. In the environment, arsenic exists in variable forms both as inorganic and organic species. From arsenic containing compartments, plants can absorb and accumulate arsenic. Crops grown on these contaminated soils pose several-fold higher toxicity to humans compared with drinking water if arsenic enters the food chain. Information regarding arsenic transfer at different trophic levels in food chains has not been summarized until now. The present review focuses on the food chain perspective of arsenic, which affects all components of the food chain during its course. The circumstances that facilitate arsenic accumulation in flora and fauna, as components of the food chain, are outlined in this review.


Assuntos
Arsênio , Poluentes do Solo , Animais , Arsênio/análise , Arsênio/toxicidade , Produtos Agrícolas , Cadeia Alimentar , Humanos , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
9.
Ecotoxicol Environ Saf ; 222: 112459, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34217114

RESUMO

Nanotechnology is an avant-garde field of scientific research that revolutionizes technological advancements in the present world. It is a cutting-edge scientific approach that has undoubtedly a plethora of functions in controlling environmental pollutants for the welfare of the ecosystem. However, their unprecedented utilization and hysterical release led to a huge threat to the soil microbiome. Nanoparticles(NPs) hamper physicochemical properties of soil along with microbial metabolic activities within rhizospheric soils.Here in this review shed light on concentric aspects of NP-biosynthesis, types, toxicity mechanisms, accumulation within the ecosystem. However, the accrual of tiny NPs into the soil system has dramatically influenced rhizospheric activities in terms of soil properties and biogeochemical cycles. We have focussed on mechanistic pathways engrossed by microbes to deal with NPs.Also, we have elaborated the fate and behavior of NPs within soils. Besides, a piece of very scarce information on NPs-toxicity towards environment and rhizosphere communities is available. Therefore, the present review highlights ecological perspectives of nanotechnology and solutions to such implications. We have comprehend certain strategies such as avant-garde engineering methods, sustainable procedures for NP synthesis along with vatious regulatory actions to manage NP within environment. Moreover, we have devised risk management sustainable and novel strategies to utilize it in a rationalized and integrated manner. With this background, we can develop a comprehensive plan about NPs with novel insights to understand the resistance and toxicity mechanisms of NPs towards microbes. Henceforth, the orientation towards these issues would enhance the understanding of researchers for proper recommendation and promotion of nanotechnology in an optimized and sustainable manner.


Assuntos
Nanopartículas Metálicas , Microbiota , Nanopartículas , Nanopartículas/toxicidade , Rizosfera , Solo , Microbiologia do Solo
10.
Physiol Plant ; 2021 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-34245030

RESUMO

The growth and persistence of rhizobacteria in soils are highly impacted by moisture stress. In this study, we report the first transcript analysis of four Pseudomonas strains (PS1, PS2, PS3, and PS4) isolated from the root-soil interface of rice and maize associated with different moisture levels during water deprivation. Filtered Pseudomonas sp. cells incubated at low (RH10%) and high (RH85%) relative humidity showed decreased survival of all Pseudomonas sp. at RH10% when compared with RH85%. RT-PCR showed differential expression of treS (trehalose synthase), rpoS (sigma factor), mucA (alginate regulatory gene), and fliM (flagellar motor switch protein gene) in response to exposure to RH10%. However, molecular fingerprinting and nutrient assimilation profile of Pseudomonas strains demonstrated genetic and physiological variation between the four strains irrespective of water regime and host. In vitro testing of these strains showed ACC deaminase activity and gibberellic acid, abscisic acid, indole acetic acid, and exopolysaccharide production. We determined that 50 µl of 1.2 × 103 CFU ml-1 of these Pseudomonas strains was enough to protect Arabidopsis plants against drought stress in a pot experiment. Inoculated plants increased their root colonization ability and biomass; however, PS2 showed higher survival (95%), relative water content (59%), chlorophyll (30%), glycine betaine (38%), proline (23%), and reduced MDA (43%) in shoots than irrigated control under induced water deprivation. It can be concluded that all Pseudomonas strains were effective in mitigating drought stress, however, PS2 appears to impart more resistance to drought than the other strains by upregulating key defense mechanisms.

11.
Plant Physiol Biochem ; 166: 160-176, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34116336

RESUMO

Drought tolerant plant growth-promoting rhizobacteria (PGPR) can confer drought tolerance in plants, when inoculated, and this effect can be more pronounced by their combined application with silicon oxide nanoparticles (SiO2 NPs). In this research, drought-tolerant and plant growth-promoting rhizobacterial strains were isolated from the rhizospheric soil of wheat plants growing in the arid region of Pakistan. Out of 30 isolated strains, three rhizobacterial strains were selected based on their drought tolerance, higher phytohormones (indole acetic acid (IAA), abscisic acid (ABA), and cytokinin (CK), and osmolyte (proline and sugar) production ability. These strains were identified as Bacillus sp. Azospirillum lipoferum and Azospirillum brasilense by 16S rRNA sequencing and accession numbers (MT482404, MT742664, and MT 742666, respectively) were obtained. Inoculation of these strains, alone and in combination, improved the germination attributes of wheat seeds under drought stress conditions. However, the combination of all three bacterial strains gave the best results. SiO2 NPs were prepared from silicon dioxide and characterized by scanning electron microscopy (SEM), Energy dispersive X-rays pattern (EDX), and UV-visible spectrum. The effect of SiO2 NPs was also tested on wheat seeds under drought stress and it was observed that SiO2 NPs (150 mg/L) create pronounced drought ameliorative potential in wheat seedlings. In the pot experiment, the combined application of SiO2 NPs and PGPR exhibited a synergistic role and improved the growth and yield of wheat. The interaction between SiO2 NPs and bacterial combination improved biomass (fresh and dry weight), and chlorophyll-a, b content by 138.78%, 65.70%, 128.57%, and 283.33% respectively as compared to untreated but drought exposed plants. They also improved relative water content (71.66%), gas exchange attributes, increased nutrients uptake, and osmolytes production of wheat. Up-regulation of antioxidant enzymes; superoxide dismutase (60.49%), peroxidase (55.99%), and catalase (81.69%) was also observed. This research work suggested that the application of SiO2 NPs and PGPR strains induced drought tolerance in wheat by modulating different physiological and metabolic processes in plants which ultimately improved the growth and yield of wheat under drought stress.


Assuntos
Secas , Triticum , Desenvolvimento Vegetal , Raízes de Plantas , RNA Ribossômico 16S , Dióxido de Silício
12.
Ecotoxicol Environ Saf ; 220: 112401, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34118747

RESUMO

Cadmium (Cd) is a trace element causing severe toxicity symptoms in plants, besides posing hazardous fitness issue due to its buildup in the human body through food chain. Nanoparticles (NPs) are recently employed as a novel strategy to directly ameliorate the Cd stress and acted as nano-fertilizers. The intend of the current study was to explore the effects of zinc oxide nanoparticles (ZnO-NPs; 50 mg/L) on plant growth, photosynthetic activity, elemental status and antioxidant activity in Oryza sativa (rice) under Cd (0.8 mM) stress. To this end, the rice plants are treated by Cd stress at 15 days after sowing (DAS), and the treatment was given directly into the soil. Supply of ZnO-NPs as foliar spray was given for five consecutive days from 30 to 35 DAS, and sampling was done at 45 DAS. However, rice plants supplemented with ZnO-NPs under the Cd toxicity revealed significantly increased shoot length (SL; 34.0%), root fresh weight (RFW; 30.0%), shoot dry weight (SDW; 23.07%), and root dry weight (RDW; 12.24%). Moreover, the ZnO-NPs supplement has also positive effects on photosynthesis related parameters, SPAD value (40%), chloroplast structure, and qualitatively high fluorescence observed by confocal microscopy even under Cd stress. ZnO-NPs also substantially prevented the increases of hydrogen peroxide (H2O2) and malondialdehyde (MDA) triggered by Cd. Physiological and biochemical analysis showed that ZnO-NPs increased enzymatic activities of superoxide dismutase (SOD; 59%), catalase (CAT; 52%), and proline (17%) that metabolize reactive oxygen species (ROS); these increases coincided with the changes observed in the H2O2 and MDA accumulation after ZnO-NPs application. In conclusion, ZnO-NPs application to foliage has great efficiency to improve biomass, photosynthesis, protein, antioxidant enzymes activity, mineral nutrient contents and reducing Cd levels in rice. This can be attributed mainly from reduced oxidative damage resulted due to the ZnO-NPs application.


Assuntos
Antioxidantes/metabolismo , Cádmio/efeitos adversos , Nanopartículas , Oryza/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Poluentes do Solo/efeitos adversos , Óxido de Zinco/farmacologia , Biomassa , Catalase/metabolismo , Produtos Agrícolas/efeitos adversos , Produtos Agrícolas/fisiologia , Fertilizantes , Humanos , Peróxido de Hidrogênio/metabolismo , Malondialdeído/metabolismo , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Oryza/fisiologia , Estresse Oxidativo/efeitos dos fármacos , Folhas de Planta , Solo/química , Superóxido Dismutase/metabolismo , Óxido de Zinco/administração & dosagem
14.
Plant Physiol Biochem ; 165: 187-195, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34049031

RESUMO

Predicted changes in climate, with more severe droughts and more extreme weather variability, are gaining considerable attention from stakeholders because of the already stressed and seriously challenging agricultural ecosystems of the contemporary world. One of the greatest challenges faced by these unique ecosystems due to climate change is drought stress, which affects plant growth, development and metabolic processes, thus reducing production, yield, and quality of crop plants. Plants counter this stress by employing complex mechanisms through a series of physiological, cellular, and molecular processes. Among the myriad of stress tolerance mechanisms, the positive effects of Si on water status of plants have been widely appreciated. Here, we review the potential of Si supplementation in alleviating drought stress and highlight the imported mechanisms involved in Si mediated reduction of drought stress in plants. Si fertilization not only enhances the photosynthetic pigments, growth, biomass, antioxidant enzymes, gene expression, osmolyte concentrations and nutrient uptake but also improves crop production, yield and grain quality during drought stress. In addition, it provides insights on important mechanisms involved in the modification of gas exchange attributes, gene modification, nutritional homeostasis, control synthesis of compatible solutes, osmotic adjustment and stimulation of phytohormone biosynthesis and antioxidant enzymes under drought stress. We also highlight knowledge gaps and future research prospects to understand Si mediated role in alleviating drought stress.


Assuntos
Secas , Silício , Ecossistema , Plantas , Estresse Fisiológico
15.
Ecotoxicol Environ Saf ; 218: 112293, 2021 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-33957422

RESUMO

Nanoparticles (NPs) have recently emerged as potential agents for plants to ameliorate abiotic stresses by acting as nano-fertilizers. In this regard, the influence of the zinc oxide nanoparticles (ZnO-NPs) on plant responses to copper (Cu) stress has been poorly understood. Hence, the present study was executed to explore the role of ZnO-NPs (foliar) and 24-epibrassinolide (EBL; root dipping) individually or in combined form in the resilience of tomato (Solanum lycopersicum) plant to Cu stress. Tomato seeds were sown to make the nursery; and at 20 days after sowing (DAS) the plantlets were submerged in 10-8 M of EBL solution for 2 h, and subsequently transplanted in the soil-filled earthen pots. Cu concentration (100 mg kg-1) was applied to the soil at 30 DAS, whereas at 35 DAS plants were sprinkled with double distilled water (DDW; control), 50 mg/L of Zinc (Zn) and 50 mg/L of ZnO-NPs; and plant performance were evaluated at 45 DAS. It was evident that Cu-stress reduced photosynthesis (17.3%), stomatal conductance (18.1%), plant height (19.7%), and nitrate reductase (NR) activity (19.2%), but increased malondialdehyde (MDA; 29.4%), superoxide radical (O2-; 22.3%) and hydrogen peroxide (H2O2; 26.2%) content in S. lycopersicum. Moreover, ZnO-NPs and/or EBL implemented via different modes improved photosynthetic activity, stomatal aperture, growth, cell viability and activity of antioxidant enzymes and proline that augmented resilience of tomato plants to Cu stress. These observations depicted that application of ZnO-NPs and EBL could be a useful approach to assist Cu confiscation and stress tolerance against Cu in tomato plants grown in Cu contaminated sites.

16.
Ecotoxicol Environ Saf ; 218: 112262, 2021 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-33964549

RESUMO

Salinity is a key devastating abiotic factor that hinders the development and yield of safflower. The sole and combined application of zinc oxide nanoparticles (ZnO-NPs) and a biofertilizer (BF) to improve salt tolerance in safflower has not been thoroughly explored. The response of safflower plants in a pot experiment to the foliar spray of ZnO-NPs alone and in combination with a BF was thus detected. We determined that a ZnO-NP concentration of 17 mg/L was sufficient to protect safflower against salinity (250 mM NaCl) by increasing the plant productivity, percent water content, and osmolyte levels. Coapplication of ZnO-NPs and Phytoguard protected safflower plants from salinity stress by improving the activities of antioxidant enzymes and decreasing the levels of proline (leaves (61%) and roots (63%)) and malondialdehyde (MDA) (leaves (54%) and roots (65%)). Under salt stress, the Na+ content increased, while seed coating with biofertilizer and ZnO-NP spray significantly decreased the Na+ concentration (74% in leaves and 60% in roots). For the K+ concentration, however, antagonistic outcomes were observed. Additionally, the combined treatment significantly enhanced agronomic parameters such as the number of leaves and pods per plant, capitulum weight, and the number of yellow and wilted leaves per plant under salinity stress. Thus, ZnO-NPs could be an effective bio-source for the protection of safflower plants under salinity stress. Our findings showed that in the combined treatment of ZnO-NPs and biofertilizer, the salinity tolerance was more pronounced than in the single treatment and untreated control. A thorough analysis at the molecular level, however, is still required to understand the mechanism by which ZnO-NPs and BF in safflower plants alleviate salt stress.

17.
Chemosphere ; 279: 130522, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33866104

RESUMO

Cadmium is a highly mobile toxic heavy metal and a serious hazard to the biosphere. We studied uptake, accumulation and elimination of cadmium in a soil - faba bean - aphid - ladybird food chain. The soil in the study was amended with Cd at concentrations 0, 5, 10, 20 and, 30 mg kg-1 (w/w). We noted significant Cd transfer in a dose-dependent manner. Cadmium biomagnified in faba bean roots and aphids while biominimized in ladybirds as revealed by their respective transfer coefficients. The concentration-dependent removal of Cd from aphids through excretion via honeydew as well as through pupal exuviae of ladybirds during metamorphosis links to possible mechanisms of Cd detoxification at these trophic levels, which regulates the bioaccumulation of Cd along the food chain. These findings press for the advance studies to find and understand the physiological pathways and mechanisms leading to bio-minimization of Cd across the food chain.


Assuntos
Afídeos , Poluentes do Solo , Vicia faba , Animais , Cádmio/análise , Cadeia Alimentar , Solo , Poluentes do Solo/análise
18.
Environ Pollut ; 280: 116992, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33784567

RESUMO

Lead (Pb) is an environmental pollutant that negatively affects rice plants, causing damage to the root system and chloroplast structures, as well as reducing growth. 24-Epibrasnolide (EBR) is a plant growth regulator with a high capacity to modulate antioxidant metabolism. The objective of this research was to investigate whether exogenous EBR application can mitigate oxidative damage in Pb-stressed rice plants, measure anatomical structures and evaluate physiological and biochemical responses connected with redox metabolism. The experiment was randomized with four treatments, including two lead treatments (0 and 200 µM PbCl2, described as - Pb and + Pb, respectively) and two treatments with brassinosteroid (0 and 100 nM EBR, described as - EBR and + EBR, respectively). The results revealed that plants exposed to Pb suffered significant disturbances, but the EBR alleviated the negative interferences, as confirmed by the improvements in the root structures and antioxidant system. This steroid stimulated the root structures, increasing the epidermis thickness (26%) and aerenchyma area (50%), resulting in higher protection of this tissue against Pb2+ ions. Additionally, EBR promoted significant increases in superoxide dismutase (26%), catalase (24%), ascorbate peroxidase (54%) and peroxidase (63%) enzymes, reducing oxidative stress on the photosynthetic machinery in Pb-stressed plants. This research proved that EBR mitigates the toxic effects generated by Pb in rice plants.


Assuntos
Brassinosteroides , Oryza , Antioxidantes , Brassinosteroides/metabolismo , Chumbo/toxicidade , Oryza/metabolismo , Estresse Oxidativo , Folhas de Planta/metabolismo , Esteroides Heterocíclicos
19.
J Hazard Mater ; 415: 125585, 2021 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-33721774

RESUMO

A field study was designed to explore the impacts of foliar-applied chemically and green synthesized titanium dioxide nanoparticles (TiO2 NPs) on cadmium (Cd) uptake in wheat plants. The wheat was grown in field which was contaminated with Cd and plants were subjected to foliar episodes of TiO2 NPs during plant growth period. Leaf extracts of two plant species (Trianthema portulacastrum, Chenopodium quinoa) were used for green synthesis while sol-gel method was used for chemical preparation of TiO2 NPs. Results showed that TiO2 NPs significantly enhanced the plant height, length of spikes photosynthesis, and straw and grain yield compared to control. TiO2 NPs minimized the oxidative burst in leaves and improved the enzyme activities than control. Cadmium concentrations of straw, roots and grains decreased after TiO2 NPs treatments than control. The grain Cd contents were below recommended threshold (0.2 mg Cd /kg grain DW) for cereals upon NPs exposure. The health risk index by the dietary use of grains for adults was below threshold upon NPs exposure. Overall, foliar use of TiO2 NPs prepared from plant extracts was appropriate in minimizing Cd contents in wheat grains, thereby reducing risk of Cd to human health via food chain.


Assuntos
Nanopartículas , Poluentes do Solo , Cádmio/análise , Cádmio/toxicidade , Humanos , Solo , Poluentes do Solo/análise , Titânio , Triticum
20.
Photosynth Res ; 2021 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-33783665

RESUMO

Maize is a low-temperature (LT)-sensitive plant and its physiological responses towards LT of temperate regions developed is an adaptive trait. To further our understanding about the response of maize to LT at the physiological and photosynthesis level, we conducted Infrared Gas Analysis (IRGA using LICOR6400-XT in 45-day-old grown two maize genotypes, one from temperate region (Gurez-Kashmir Himalayas), viz., Gurez local (Gz local), and another from tropics (Gujarat), viz., GM6. This study was carried out to evaluate the underlying physiological mechanisms in the two differentially temperature-tolerant maize genotypes. Net photosynthetic rate (A/PN), 18.253 in Gz local and 25.587 (µmol CO2 m-2 s-1) in GM6; leaf conductance (gs), 0.0102 in Gz local and 0.0566 (mmol H2O m-2 s-1) in GM6; transpiration rate (E), 0.5371 in Gz local and 2.9409 (mmol H2O m-2 s-1) in GM6; and water use efficiency (WUE), 33.9852 in Gz local and 8.7224 (µmol CO2 mmol H2O-1) in GM6, were recorded under ambient conditions. Also, photochemical efficiency of photosystem II (PSII) (Fv/Fm), 0.675 in Gz local and 0.705 in GM6; maximum photochemical efficiency (Fv'/Fm'), 0.310234 in Gz local and 0.401391 in GM6; photochemical quenching (qP), 0.2375 in Gz local and 0.2609 in GM6; non-photochemical quenching (NPQ), 2.0036 in Gz local and 1.1686 in GM6; effective yield of PSII (ФPSII), 0.0789 in Gz local and 0.099 in GM6; and electron transport rate (ETR), 55.3152 in Gz local and 68.112 in GM6, were also evaluated in addition to various response curves, like light intensities and temperature. We observed that light response curves show the saturation light intensity requirement of 1600 µmol for both the genotypes, whereas temperature response curves showed the optimum temperature requirement for Gz local as 20 °C and for GM6 it was found to be 35 °C. The results obtained for each individual parameter and other correlational studies indicate that IRGA forms a promising route for quick and reliable screening of various stress-tolerant valuable genotypes, forming the first study of its kind.

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