The pesticide thiamethoxam induced toxicity in Brassica juncea and its detoxification by Pseudomonas putida through biochemical and molecular modifications.

Insecticides are extensively exploited by humans to destroy the pests one such compound thiamethoxam is widely used over crops to offer control over wide-array of sucking insect pests. The present study unravels the detoxification potential of Pseudomonas putida in thiamethoxam exposed B. juncea seedlings. The thiamethoxam application curtailed the fresh weight, dry weight and seedling length by 106.22%, 80.29% and 116.78% while P. putida revived these growth parameters in thiamethoxam exposed B. juncea seedlings by 59.65%, 72.99% and 164.56% respectively. The exogenous supplementation of P. putida resuscitated the photosynthetic efficiency of B. juncea seedlings exposed to thiamethoxam as total chlorophyll, chlorophyll a, chlorophyll b, carotenoid, flavonoid and anthocyanin contents were enhanced by 169.42%, 62.90%, 72.89%, 78.53%, 47.36% and 515.15% respectively in contrast to TMX exposed seedlings. Further, P. putida pre-treatment reinvigorated the osmoprotectant content in B. juncea seedlings grown in thiamethoxam as trehalose, glycine betaine and proline contents were thrusted by 21.20%, 58.98% and 34.26% respectively. The thiamethoxam exposure exorbitated the superoxide anion, hydrogen peroxide and MDA levels by 223.03%, 130.18% and 74.63% while P. putida supplementation slackened these oxidative burst levels by 41.75%, 3.79% and 29.09% respectively in thiamethoxam treated seedlings. Notably, P. putida inoculation in thiamethoxam exposed seedlings upregulated the enzymatic antioxidant and non-enzymatic antioxidant activities as SOD, CAT and glutathione were enhanced by 163.76%, 99.29% and 114.91% respectively in contrast to thiamethoxam treated seedlings. The gene expression analysis exhibited the negative impact of thiamethoxam on B. juncea seedlings as conferred by upregulation of chlorophyllase by 443.86 folds whereas P. putida application in thiamethoxam exposed seedlings downregulated the chlorophyllase expression by 248.73 folds and upregulated CXE, GST, NADH and POD genes by 0.44, 4.07, 1.43 and 0.98 folds respectively suggesting the molecular-level thiamethoxam detoxification efficiency of P. putida.

Interactive effect of 24-epibrassinolide and plant growth promoting rhizobacteria inoculation restores photosynthetic attributes in Brassica juncea L. under chlorpyrifos toxicity.

Chlorpyrifos (CP) is a commonly used organophosphorous pesticide that is frequently utilised in the agricultural industry because of its great efficiency and inexpensive cost. The focus of the present study was to assess the impact of CP toxicity on Brassica juncea L. and to unravel the ameliorative potential of phytohormone, 24-epibrassinolide (EBL) mediated plant-microbe (Pseudomonas aeruginosa (B1), Burkholderia gladioli (B2)) interaction in B. juncea L. The maximum significant increment in the total chlorophyll, carotenoids, xanthophyll, anthocyanin and flavonoid content with EBL and B2 treatment in CP stressed B. juncea seedlings on spectrophotometric analysis were observed. Autofluorescence imaging of photosynthetic pigments i.e. chlorophyll, carotenoids, and total phenols with confocal microscopy showed maximum fluorescence with EBL and B2. Furthermore, when compared to CP stressed seedlings, scanning electron microscopy (SEM) study of the abaxial surface of leaves revealed a recovery in stomatal opening. The supplementation of EBL and PGPR (plant growth promoting rhizobacteria) improved the level of psb A (D1 subunit PSII) and psb B (CP 47 subunit of PSII) genes expression. The expression analysis of chalcone synthase (CHS), Phenylalanine ammonialyase (PAL), Phyotene synthase (PSY) with RT-PCR system showed up-regulation in the expression when supplemented with EBL and PGPR. As a result, the current study suggests that EBL and PGPR together, can reduce CP-induced toxicity in B. juncea seedlings and recovering the seedling biomass.

India-discovered levonadifloxacin & alalevonadifloxacin: A review on susceptibility testing methods, CLSI quality control and breakpoints along with a brief account of their emerging therapeutic profile as a novel standard-of-care.

BACKGROUND: Levonadifloxacin (intravenous) and alalevonadifloxacin (oral prodrug) are novel antibiotics based on benzoquinolizine subclass of fluoroquinolone, licensed for clinical use in India in 2019. The active moiety, levonadifloxacin, is a broad-spectrum antibiotic with a high potency against methicillin-resistant Staphylococcus. aureus, multi-drug resistant pneumococci and anaerobes. OBJECTIVE: This review, for the first time, critically analyses the antimicrobial susceptibility testing methods, Clinical Laboratory & Standards Institute (CLSI)-quality control of susceptibility testing and breakpoints of levonadifloxacin. Further, the genesis, discovery and developmental aspects as well as therapeutic profile of levonadifloxacin and alalevonadifloxacin are briefly described. CONTENTS: In order to aid the scientific and clinician communities with a single comprehensive overview on all the key aspects of levonadifloxacin and alalevonadifloxacin, the present article covers the reference MIC and disk diffusion methods for levonadifloxacin susceptibility testing that were approved by CLSI and the reference ranges for quality control strains published in the CLSI M100 document. The breakpoints of levonadifloxacin were derived in concordance to US FDA, European Committee on Antibiotic Susceptibility Testing (EUCAST) and CLSI approaches. Further, the article provides a brief account of challenges encountered during the discovery stages of levonadifloxacin and alalevonadifloxacin, activity spectrum and safety benefits accruing from structural novelty-linked mechanism of action. Further, the review also covers in vitro and in vivo activities, registrational clinical studies and patient-friendly features of levonadifloxacin/alalevonadifloxacin. Cumulatively, levonadifloxacin has a potential to offer a long awaited new standard-of-care treatment for the resistant Gram-positive bacterial infections.

Amelioration of Chromium-Induced Oxidative Stress by Combined Treatment of Selected Plant-Growth-Promoting Rhizobacteria and Earthworms via Modulating the Expression of Genes Related to Reactive Oxygen Species Metabolism in Brassica juncea.

Chromium (Cr) toxicity leads to the enhanced production of reactive oxygen species (ROS), which are extremely toxic to the plant and must be minimized to protect the plant from oxidative stress. The potential of plant-growth-promoting rhizobacteria (PGPR) and earthworms in plant growth and development has been extensively studied. The present study was aimed at investigating the effect of two PGPR (Pseudomonas aeruginosa and Burkholderia gladioli) along with earthworms (Eisenia fetida) on the antioxidant defense system in Brassica juncea seedlings under Cr stress. The Cr toxicity reduced the fresh and dry weights of seedlings, enhanced the levels of superoxide anion (O2•-), hydrogen peroxide (H2O2), malondialdehyde (MDA), and electrolyte leakage (EL), which lead to membrane as well as the nuclear damage and reduced cellular viability in B. juncea seedlings. The activities of the antioxidant enzymes, viz., superoxide dismutase (SOD), guaiacol peroxidase (POD), ascorbate peroxidase (APOX), glutathione peroxidase (GPOX), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) were increased; however, a reduction was observed in the activity of catalase (CAT) in the seedlings under Cr stress. Inoculation of the PGPR and the addition of earthworms enhanced the activities of all other antioxidant enzymes except GPOX, in which a reduction of the activity was observed. For total lipid- and water-soluble antioxidants and the non-enzymatic antioxidants, viz., ascorbic acid and glutathione, an enhance accumulation was observed upon the inoculation with PGPR and earthworms. The supplementation of PGPR with earthworms (combined treatment) reduced both the reactive oxygen species (ROS) and the MDA content by modulating the defense system of the plant. The histochemical studies also corroborated that the combined application of PGPR and earthworms reduced O2•-, H2O2, lipid peroxidation, and membrane and nuclear damage and improved cell viability. The expression of key antioxidant enzyme genes, viz., SOD, CAT, POD, APOX, GR, DHAR, and GST showed the upregulation of these genes at post-transcriptional level upon the combined treatment of the PGPR and earthworms, thereby corresponding to the improved plant biomass. However, a reduced expression of RBOH1 gene was noticed in seedlings supplemented under the effect of PGPR and earthworms grown under Cr stress. The results provided sufficient evidence regarding the role of PGPR and earthworms in the amelioration of Cr-induced oxidative stress in B. juncea.

Amelioration of oxidative stress by trans-Anethole via modulating phase I and phase II enzymes against hepatic damage induced by CCl4 in male Wistar rats.

The current study was designed to assess the in vivo hepatoprotective properties of trans-Anethole, which is a principal aromatic component of star anise. The hepatoprotective effects of trans-Anethole were evaluated at three doses [40, 80, and 160 mg/kg body weight (b.wt.)] against carbon tetrachloride (CCl4)-induced hepatic damage in male Wistar rats for 4 weeks. Forty-two male Wistar rats were equally divided into seven groups; the control (group I) received only distilled water. Rats of group II received CCl4 (1 ml/kg b.wt.) in a 1:1 ratio of CCl4 and olive oil via intraperitoneal doses, while rats of group III received silymarin (50 mg/kg b.wt.), followed by CCl4 intraperitoneal doses, 3 days in a week. Rats of group IV received trans-anethole (160 mg/kg b.wt.) for 28 days as a negative control. Trans-anethole at the doses of 40, 80, and 160 mg/kg b.wt. was administered to groups V, VI, and VII, respectively, for 28 days, followed by CCl4 (i.p). Results showed that CCl4 treatment (group II) elevated the levels of different serum markers like aspartate aminotransferase (AST) by 4.74 fold, alanine aminotransferase (ALT) by 3.47 fold, aspartate alkaline phosphatase (ALP) by 3.55 fold, direct bilirubin by 3.48 fold, and total bilirubin by 2.38 fold in contrast to control. Furthermore, it was found that the decreased levels of liver antioxidant enzymes viz. catalase (CAT) and glutathione reductase (GR) were significantly modulated by the pre-administration of rats with different doses (40, 80, and 160 mg/kg b.wt.) of trans-anethole. Furthermore, pre-treatment of trans-anethole reduced the level of phase I enzymes and elevated the level of phase II detoxifying enzymes. Histopathological investigations showed that the treatment with trans-anethole was effective in ameliorating CCl4-induced liver injury and restored the normal hepatic architecture. Moreover, trans-anethole restored p53 and cyclin D levels in liver tissue relative to group II. Western blot analysis revealed that the trans-anethole treatment downregulated the expression of Bax and caspase-3 while upregulated the expression of Bcl-xL. Collectively, the findings of the study showed the strong efficacy of trans-anethole in ameliorating the hepatic damage caused by CCl4 through the modulation of antioxidants and xenobiotic-metabolizing enzymes.

Herbal immune-boosters: Substantial warriors of pandemic Covid-19 battle.

Current scenario depicts that world has been clenched by COVID-19 pandemic. Inevitably, public health and safety measures could be undertaken in order to dwindle the infection threat and mortality. Moreover, to overcome the global menace and drawing out world from moribund stage, there is an exigency for social distancing and quarantines. Since December, 2019, coronavirus, SARS-CoV-2 (COVID-19) have came into existence and up till now world is still in the state of shock.At this point of time, COVID-19 has entered perilous phase, creating havoc among individuals, and this has been directly implied due to enhanced globalisation and ability of the virus to acclimatize at all conditions. The unabated transmission is due to lack of drugs, vaccines and therapeutics against this viral outbreak. But research is still underway to formulate the vaccines or drugs by this means, as scientific communities are continuously working to unravel the pharmacologically active compounds that might offer a new insight for curbing infections and pandemics. Therefore, the topical COVID-19 situation highlights an immediate need for effective therapeutics against SARS-CoV-2. Towards this effort, the present review discusses the vital concepts related to COVID-19, in terms of its origin, transmission, clinical aspects and diagnosis. However, here, we have formulated the novel concept hitherto, ancient means of traditional medicines or herbal plants to beat this pandemic.

Foliar Application of 24-Epibrassinolide Improves Growth, Ascorbate-Glutathione Cycle, and Glyoxalase System in Brown Mustard (Brassica juncea (L.) Czern.) under Cadmium Toxicity.

Cadmium (Cd) metal toxicity is a crucial ecological matter that requires immediate efforts to mitigate it. Brassica juncea plants were exposed to Cd (0 and 200 µM as CdSO4) and foliar application of 24-Epibrassinolide (EBR) (0, 10-7 and 10-5 M). The toxic effect of Cd was evident in terms of declined growth and biomass yield, lowered levels of pigment content and chlorophyll fluorescence, and reduction in gas exchange attributes. The levels of proline and glycinebetaine increased in response to Cd treatment. There was an imperative rise in the contents of H2O2 and malondialdehyde as well as electrolyte leakage in the Cd-stressed plants. With the application of EBR, there was a significant replenishment in growth attributes and photosynthetic efficacy. The contents of ROS (reactive oxygen species) and malondialdehyde as well as electrolyte leakage were reduced by the hormone supplementation. Enhancement in the contents of glutathione and ascorbic acid, and the activities of enzymes of the antioxidative defense system and glyoxalase system was recorded in response to Cd as well as hormone treatment. The in situ levels of Cd in roots and shoot were augmented in response to Cd treatment, but were found to be lowered by the EBR application.

Efficacy of Lactobacillus paracasei HA-196 and Bifidobacterium longum R0175 in Alleviating Symptoms of Irritable Bowel Syndrome (IBS): A Randomized, Placebo-Controlled Study.

Specific probiotic strains can alleviate the gastrointestinal (GI) symptoms and psychiatric comorbidities of irritable bowel syndrome (IBS). In this randomized, double-blind, placebo-controlled study, the efficacy of Lactobacillus paracasei HA-196 (L. paracasei) and Bifidobacterium longum R0175 (B. longum) in reducing the GI and psychological symptoms of IBS was evaluated in 251 adults with either constipation (IBS-C), diarrhea (IBS-D), or mixed-pattern (IBS-M). Following a 2-week run-in period, participants were randomized to one of three interventions: L. paracasei (n = 84), B. longum (n = 83) or placebo (n = 81). IBS symptoms, stool frequency and consistency and quality of life were assessed by questionnaires. The differences from baseline in the severity of IBS symptoms at 4 and 8 weeks were similar between groups. Participants in this study were classified, after randomization, into subtypes according to Rome III. Within the L. paracasei group, complete spontaneous and spontaneous bowel movement frequency increased in participants with IBS-C (n = 10) after 8 weeks of supplementation (both p < 0.05) and decreased in participants with IBS-D (n = 10, p = 0.013). Both L. paracasei and B. longum supplementation improved the quality of life in emotional well-being and social functioning compared with baseline (all p < 0.05). In conclusion, L. paracasei and B. longum may reduce GI symptom severity and improve the psychological well-being of individuals with certain IBS subtypes.

Impact of Plant Growth Promoting Rhizobacteria in the Orchestration of Lycopersicon esculentum Mill. Resistance to Plant Parasitic Nematodes: A Metabolomic Approach to Evaluate Defense Responses Under Field Conditions.

The present study deals with biological control of Meloidogyne incognita in 45-days old Lycopersicon esculentum, inoculated with Pseudomonas aeruginosa(M1) and Burkholderia gladioli (M2). The improved plant growth and biomass of nematode infested Plant growth promoting rhizobacteria (PGPR) inoculated plants was observed. Remarkable reduction in the numbers of second stage juvenile (J2s), root galls was recorded after treatment of microbes relative to experimental controls. Moreover, the lowered activities of oxidative stress markers (H2O2 (hydrogen peroxide), O2- (superoxide anion), malondialdehyde (MDA)) was estimated in plants after rhizobacterial supplementation. Higher activities of enzymatic (SOD (Superoxide dismutase), POD (Guaiacol peroxidase), CAT (Catalase), GPOX (Glutathione peroxidase), APOX (Ascorbate peroxidase), GST (Glutathione-S-transferase), GR (Glutathione reductase), DHAR (Dehydroascorbate reductase), PPO (Polyphenol oxidase)) and non-enzymatic (glutathione, ascorbic acid, tocopherol) antioxidants were further determined in nematode infected plants following the addition of bacterial strains. The upregulation of photosynthetic activities were depicted by evaluating plant pigments and gas exchange attributes. An increase in the levels of phenolic compounds (total phenols, flavonoids, anthocyanins), osmoprotectants (total osmolytes, carbohydrates, reducing sugars, trehalose, proline, glycine betaine, free amino acids) and organic acids (fumaric, succinic, citric, malic acid) were reflected in infected plants, showing further enhancement after application of biocontrol agents. The study revealed the understanding of plant metabolism, along with the initiative to commercially exploit the biocontrol agents as an alternative to chemical nematicides in infected fields for sustainable agriculture.

Isolation of Phytochemicals from Bauhinia variegata L. Bark and Their In Vitro Antioxidant and Cytotoxic Potential.

Plants have been the basis of traditional medicine since the dawn of civilizations. Different plant parts possess various phytochemicals, playing important roles in preventing and curing diseases. Scientists, through extensive experimental studies, are playing an important part in establishing the use of phytochemicals in medicine. However, there are still a large number of medicinal plants which need to be studied for their phytochemical profile. In this study, the objective was to isolate phytochemicals from bark of Bauhinia variegata L. and to study them for their antioxidant and cytotoxic activities. The bark was extracted with methanol, followed by column chromatography and thus isolating kaempferol, stigmasterol, protocatechuic acid-methyl ester (PCA-ME) and protocatechuic acid (PCA). 2,2-azinobis-3-ethyl-benzothiazoline-6-sulfonic acid (ABTS) and 2, 2'-diphenyl-1-picrylhydrazyl radical (DPPH) radical scavenging assays were utilized for assessment of antioxidant activity, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) dye reduction assay was used to determine cytotoxic activity against C-6 glioma rat brain, MCF-7 breast cancer, and HCT-15 colon cancer cell lines. The compounds were found to have significant antioxidant and cytotoxic activity. Since there is a considerable increase in characterizing novel chemical compounds from plant parts, the present study might be helpful for chemotaxonomic determinations, for understanding of medicinal properties as well as for the quality assessment of herbal supplements containing B. variegata bark, thus establishing its use in traditional medicine.

Metal resistant PGPR lowered Cd uptake and expression of metal transporter genes with improved growth and photosynthetic pigments in Lycopersicon esculentum under metal toxicity.

Plant growth promoting rhizobacteria (PGPRs) are very effective in immobilization of heavy metals and reducing their translocation in plants via precipitation, complex formation and adsorption. The present study was therefore designed to understand the role of Pseudomonas aeruginosa and Burkholderia gladioli in mitigation of Cd stress (0.4 mM) in 10-days old L. esculentum seedlings. The present work investigated growth characteristics, photosynthetic pigments, metal tolerance index, metal uptake and the contents of metal chelating compounds (protein bound and non-protein bound thiols, total thiols) in microbes inoculated Cd treated L. esculentum seedlings. The gene expression profiling of different metal transporters was conducted in order to investigate the quantitative analysis. Our results revealed Cd generated toxicity in seedlings in terms of reduced growth (root length, shoot length and fresh weight) and photosynthetic pigments (chlorophyll, carotenoid and xanthophyll) which enhanced upon inoculations of P. aeruginosa and B. gladioli. Further, the metal uptake along with levels of protein and non-protein bound thiols was also enhanced in Cd-treated seedlings. Gene expression studies suggested enhanced expression in the metal transporter genes which were further declined in the microbe supplemented seedlings. Therefore, micro-organisms possess growth promoting traits that enable them to reduce metal toxicity in plants.

In-situ localization and biochemical analysis of bio-molecules reveals Pb-stress amelioration in Brassica juncea L. by co-application of 24-Epibrassinolide and Salicylic Acid.

Lead (Pb) toxicity is a major environmental concern affirming the need of proper mitigation strategies. In the present work, potential of combined treatment of 24-Epibrassinolide (24-EBL) and Salicylic acid (SA) against Pb toxicity to Brassica juncea L. seedlings were evaluated. Seedlings pre-imbibed in EBL (0.1 mM) and SA (1 mM) individually and in combination, were sown in Pb supplemented petri-plates (0.25, 0.50 and 0.75 mM). Various microscopic observations and biochemical analysis were made on 10 days old seedlings of B. juncea. The toxic effects of Pb were evident with enhancement in in-situ accumulation of Pb, hydrogen peroxide (H2O2), malondialdehyde (MDA), nuclear damage, membrane damage, cell death and polyamine. Furthermore, free amino acid were lowered in response to Pb toxicity. The levels of osmoprotectants including total carbohydrate, reducing sugars, trehalose, proline and glycine betaine were elevated in response to Pb treatment. Soaking treatment with combination of 24-EBL and SA led to effective amelioration of toxic effects of Pb. Reduction in Pb accumulation, reactive oxygen content (ROS), cellular damage and GSH levels were noticed in response to treatment with 24-EBL and SA individual and combined levels. The contents of free amino acid, amino acid profiling as well as in-situ localization of polyamine (spermidine) was recorded to be enhanced by co-application of 24-EBLand SA. Binary treatment of 24-EBL and SA, further elevated the content of osmoprotectants. The study revealed that co-application of combined treatment of 24-EBL and SA led to dimination of toxic effects of Pb in B. juncea seedlings.

Cd induced generation of free radical species in Brassica juncea is regulated by supplementation of earthworms in the drilosphere.

The antioxidant defense system of Brassica juncea under Cd stress was examined on supplementation of earthworms in the rhizosphere at different concentrations of Cd (0.50, 0.75, 1.00 and 1.25 mM i.e. 56, 84, 112 and 140 mg kg-1 respectively). Seedlings were raised in small pots containing soil spiked with Cd and earthworms under controlled conditions for 15 days. Improved Cd accumulation, as well as enhanced plant dry weight and metal tolerance were observed following the addition of earthworms. Earthworm supplementation reduced reactive oxygen species (ROS) generation by 7.3% for hydrogen peroxide (H2O2), 7.1% for superoxide anion (O2-), and 8.4% for malondialdehyde (MDA) in plants treated with 1.25 mM (140 mg kg-1) Cd. Confocal microscopy revealed improved cell viability and reduced H2O2 content due to enhanced antioxidative activity. Activity and expression levels of genes coding for antioxidative enzymes (superoxide dismutase; SOD, catalase; CAT, guaicol peroxidase; POD, glutathione reductase; GR, and glutathione-S-transferase; GST) were higher in plants raised in soils inoculated with earthworms, with expression of SOD increasing by 58.8%, CAT by 75%, POD by 183%, GR by 106.6%, and GST by 11.8%. Moreover, plant pigment (chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids) concentrations increased by 8%, 9.1%, 9.1%, and 7.7% respectively, in plants grown in soils supplemented with earthworms. The results of our study suggest that the addition of earthworms to soil increases antioxidative enzyme activities, gene expression in plants, and ROS inhibition, which enhances tolerance to Cd during the phytoextraction process.

Exogenous application of calcium to 24-epibrassinosteroid pre-treated tomato seedlings mitigates NaCl toxicity by modifying ascorbate-glutathione cycle and secondary metabolites.

The present study tested the efficacy of 24-epibrassinolide (EBL) and calcium (Ca) for mediating salinity tolerance in tomato. Salinity stress affected the morphological parameters of tomato as well as leaf relative water content (LRWC), photosynthetic and accessory pigments, leaf gas exchange parameters, chlorophyll fluorescence and the uptake of essential macronutrients. The salt (NaCl) treatment induced oxidative stress in the form of increased Na+ ion concentration by 146%, electrolyte leakage (EL) by 61.11%, lipid peroxidation (MDA) 167% and hydrogen peroxide (H2O2) content by 175%. Salt stress also enhanced antioxidant enzyme activities including those in the ascorbate-glutathione cycle. Plants treated with EBL or Ca after salt exposure mitigated the ill effects of salt stress, including oxidative stress, by reducing the uptake of Na+ ions by 52%. The combined dose of EBL + Ca reversed the salt-induced changes through an elevated pool of enzymes in the ascorbate-glutathione cycle, other antioxidants (superoxide dismutase, catalase), and osmoprotectants (proline, glycine betaine). Exogenously applied EBL and Ca help to optimize mineral nutrient status and enable tomato plants to tolerate salt toxicity. The ability of tomato plants to tolerate salt stress when supplemented with EBL and Ca was attributed to modifications to enzymatic and non-enzymatic antioxidants, osmolytes and metabolites.

Antioxidant and Antimutagenic Activities of Different Fractions from the Leaves of Rhododendron arboreum Sm. and Their GC-MS Profiling.

In this era of urbanization and environmental pollution, antioxidants and antimutagens derived from plants are promising safeguards for human health. In the current investigation, we analyzed the antioxidant and antimutagenic effects of the hexane, chloroform, and ethyl acetate fractions of Rhododendron arboreum Sm. leaves and determined their chemical composition. The different fractions inhibited lipid peroxidation, repressed the production of nitric oxide radicals, and prevented deoxyribose degradation. The antimutagenic activity of the leaf fractions was analyzed against 4-nitro-O-phenylenediamine, sodium azide and 2-aminofluorene mutagens in two test strains (TA-98 and TA-100) of Salmonella typhimurium. The experiment was conducted using pre- and co-incubation modes. The best results were obtained in the pre-incubation mode, and against indirect acting mutagen. The presence of a number of bioactive constituents was confirmed in the different fractions by GC-MS analysis. The study reveals the strong antioxidant and antimutagenic activity of R. arboreum leaves. We propose that those activities of R. arboreum might correspond to the combined effect of the phytochemicals identified by GC-MS analysis. To the best of our knowledge, this is the first report on the antimutagenic activity of R. arboreum leaves.

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.

Selenium mitigates cadmium-induced oxidative stress in tomato (Solanum lycopersicum L.) plants by modulating chlorophyll fluorescence, osmolyte accumulation, and antioxidant system.

Pot experiments were conducted to investigate the role of selenium in alleviating cadmium stress in Solanum lycopersicum seedlings. Cadmium (150 mg L-1) treatment caused a significant reduction in growth in terms of height and biomass accumulation and affected chlorophyll pigments, gas exchange parameters, and chlorophyll fluorescence. Selenium (10 µM) application mitigated the adverse effects of cadmium on growth, chlorophyll and carotenoid contents, leaf relative water content, and other physiological attributes. Lipid peroxidation and electrolyte leakage increased because of cadmium treatment and selenium-treated plants exhibited considerable reduction because of the decreased production of hydrogen peroxide in them. Cadmium-treated plants exhibited enhanced activity of antioxidant enzymes that protected cellular structures by neutralizing reactive free radicals. Supplementation of selenium to cadmium-treated plants (Cd + Se) further enhanced the activity of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) by 19.69, 31.68, 33.14, and 54.47%, respectively. Osmolytes, including proline and glycine betaine, increased with selenium application, illustrating their role in improving the osmotic stability of S. lycopersicum under cadmium stress. More importantly, selenium application significantly reduced cadmium uptake. From these results, it is clear that application of selenium alleviates the negative effects of cadmium stress in S. lycopersicum through the modifications of osmolytes and antioxidant enzymes.

Castasterone and citric acid treatment restores photosynthetic attributes in Brassica juncea L. under Cd(II) toxicity.

Cadmium(II) toxicity is a serious environmental issue warranting effective measures for its mitigation. In the present study, ameliorative effects of a bioactive brassinosteroid, castasterone (CS) and low molecular weight organic acid, citric acid (CA) against the Cd(II) toxicity to Brassica juncea L. were evaluated. Seeds of B. juncea treated with CS (0, 0.01, 1 and 100nM) were sown in cadmium spiked soils (0 and 0.6mmolkg-1 soil). CA (0.6mmolkg-1soil) was added to soil one week after sowing seeds. Plants were harvested 30 days after sowing. Phytotoxicity induced by Cd(II) was evident from stunted growth of the plants, malondialdehyde accumulation, reduction in chlorophyll and carotenoid contents, and leaf gas exchange parameters. Cd(II) toxicity was effectively alleviated by seed soaking with CS (100nM) and/ or soil amendment with CA (0.6mMkg-1 soil). Relative gene expression of genes encoding for some of the key enzymes of pigment metabolism were also analysed. Expression of chlorophyllase (CHLASE) was reduced, while that of phytoene synthase (PSY), and chalcone synthase (CHS) genes were enhanced with CS and/or CA treatments with respect to plants treated with Cd(II) only. Cd also affected the activities of antioxidative enzymes. Plants responded to Cd(II) by accumulation of total sugars. CS (100nM) and CA treatments further enhanced the activities of these parameters and induced the contents of secondary plant pigments (flavonoids and anthocyanins) and proline. The results imply that seed treatment with CS and soil application with CA can effectively alleviate Cd(II) induced toxicity in B. juncea by strengthening its antioxidative defence system and enhancing compatible solute accumulation.

Effect of earthworms on growth, photosynthetic efficiency and metal uptake in Brassica juncea L. plants grown in cadmium-polluted soils.

The present study has been carried out to examine the role of earthworms in phytoremediation of Cd and its effect on growth, pigment content, expression of genes coding key enzymes of pigments, photosynthetic efficiency and osmoprotectants in Brassica juncea L. plants grown under cadmium (Cd) metal stress. The effect of different Cd concentrations (0.50, 0.75, 1.0, 1.25 mM) was studied in 30 and 60-day-old plants grown in soils containing earthworms. It was observed that earthworm inoculation showed stimulatory effect on phytoremediation capacity and Cd uptake has increased by 49% (in 30-day-old plants) and 35% (in 60-day-old plants) in shoots and 13.3% (in 30-day-old plants) and 10% (in 60-day-old plants) in roots in 30 and 60-day-old plants in Cd (1.25 mM) treatments. Plant growth parameters such as root and shoot length, relative water content and tolerance index were found to increase in the presence of earthworms. Recovery in photosynthetic pigments (chlorophyll and carotenoid) and gas exchange parameters, i.e. net photosynthetic rate (P n ), stomatal conductance (G s ), intercellular CO2 concentration (C i ) and transpiration rate (E t ), was observed after earthworm's supplementation. Modulation in expression of key enzymes for pigment synthesis, i.e. chlorophyllase, phytoene synthase, chalcone synthase and phenylalanine ammonia lyase, was also observed. The results of our study revealed that earthworms help to mitigate the toxic effects produced by Cd on plant growth and photosynthetic efficiency along with enhanced phytoremediation capacity when co-inoculated with Cd in soil.

24-epibrassinolide stimulates imidacloprid detoxification by modulating the gene expression of Brassica juncea L.

BACKGROUND: Pesticides cause oxidative stress to plants and their residues persist in plant parts, which are a major concern for the environment as well as human health. Brassinosteroids (BRs) are known to protect plants from abiotic stress conditions including pesticide toxicity. The present study demonstrated the effects of seed-soaking with 24-epibrassinolide (EBR) on physiological responses of 10-day old Brassica juncea seedlings grown under imidacloprid (IMI) toxicity. RESULTS: In the seedlings raised from EBR-treated seeds and grown under IMI toxicity, the contents of hydrogen peroxide (H2O2) and superoxide anion (O.2-) were decreased, accompanied by enhanced activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione-S-transferase (GST), guaiacol peroxidase (POD) and the content of glutathione (GSH). As compared to controls, the gene expressions of SOD, CAT, GR, POD, NADH (NADH-ubiquinone oxidoreductase), CXE (carboxylesterase), GSH-S (glutathione synthase), GSH-T (glutathione transporter-1), P450 (cytochrome P450 monooxygenase) and GST1-3,5-6 were enhanced in the seedlings raised from EBR-treated seeds and grown in IMI supplemented substratum. However, expression of RBO (respiratory burst oxidase, the gene responsible for H2O2 production) was decreased in seedlings raised from EBR treated seeds and grown under IMI toxicity. Further, the EBR seed treatment decreased IMI residues by more than 38% in B. juncea seedlings. CONCLUSIONS: The present study revealed that EBR seed soaking can efficiently reduce oxidative stress and IMI residues by modulating the gene expression of B. juncea under IMI stress. In conclusion, exogenous EBR application can protect plants from pesticide phytotoxicity.