Phytofabricated gold nanoparticles as modulators of salt stress responses in spinach: implications for redox homeostasis, biochemical and physiological adaptation.

Introduction: The utilization of plant material for synthesizing nanoparticles effectively triggers physiological and biochemical responses in plants to combat abiotic stresses. Salt stress, particularly caused by NaCl, significantly affects plant morphology and physiology, leading to reduced crop yields. Understanding the mechanisms of salt tolerance is crucial for maintaining crop productivity. Methods: In this study, we examined the effects of 150 µM spinach-assisted gold nanoparticles (S-AuNPs) on various parameters related to seed germination, growth attributes, photosynthetic pigments, stomatal traits, ion concentrations, stress markers, antioxidants, metabolites, and nutritional contents of spinach plants irrigated with 50 mM NaCl. Results: Results showed that S-AuNPs enhanced chlorophyll levels, leading to improved light absorption, increased photosynthates production, higher sugar content, and stimulated plant growth under NaCl stress. Stomatal traits were improved, and partially closed stomata were reopened with S-AuNPs treatment, possibly due to K+/Na+ modulation, resulting in enhanced relative water content and stomatal conductance. ABA content decreased under S-AuNPs application, possibly due to K+ ion accumulation. S-AuNPs supplementation increased proline and flavonoid contents while reducing ROS accumulation and lipid peroxidation via activation of both non-enzymatic and enzymatic antioxidants. S-AuNPs also regulated the ionic ratio of K+/Na+, leading to decreased Na+ accumulation and increased levels of essential ions in spinach plants under NaCl irrigation. Discussion: Overall, these findings suggest that S-AuNPs significantly contribute to salt stress endurance in spinach plants by modulating various physiological attributes.

The halotolerant exopolysaccharide-producing Rhizobium azibense increases the salt tolerance mechanism in Phaseolus vulgaris (L.) by improving growth, ion homeostasis, and antioxidant defensive enzymes.

Globally, agricultural productivity is facing a serious problem due to soil salinity which often causes osmotic, ionic, and redox imbalances in plants. Applying halotolerant rhizobacterial inoculants having multifarious growth-regulating traits is thought to be an effective and advantageous approach to overcome salinity stress. Here, salt-tolerant (tolerating 300 mM NaCl), exopolysaccharide (EPS) producing Rhizobium azibense SR-26 (accession no. MG063740) was assessed for salt alleviation potential by inoculating Phaseolus vulgaris (L.) plants raised under varying NaCl regimes. The metabolically active cells of strain SR-26 produced a significant amount of phytohormones (indole-3-acetic acid, gibberellic acid, and cytokinin), ACC deaminase, ammonia, and siderophore under salt stress. Increasing NaCl concentration variably affected the EPS produced by SR-26. The P-solubilization activity of the SR-26 strain was positively impacted by NaCl, as demonstrated by OD shift in NaCl-treated/untreated NBRIP medium. The detrimental effect of NaCl on plants was lowered by inoculation of halotolerant strain SR-26. Following soil inoculation, R. azibense significantly (p ≤ 0.05) enhanced seed germination (10%), root (19%) shoot (23%) biomass, leaf area (18%), total chlorophyll (21%), and carotenoid content (32%) of P. vulgaris raised in soil added with 40 mM NaCl concentration. Furthermore, strain SR-26 modulated the relative leaf water content (RLWC), proline, total soluble protein (TSP), and sugar (TSS) of salt-exposed plants. Moreover, R. azibense inoculation lowered the concentrations of oxidative stress biomarkers; MDA (29%), H2O2 content (24%), electrolyte leakage (31%), membrane stability (36%) and Na+ ion uptake (28%) when applied to 40 mM NaCl-treated plants. Further, R. azibense increases the salt tolerance mechanism of P. vulgaris by upregulating the antioxidant defensive responses. Summarily, it is reasonable to propose that EPS-synthesizing halotolerant R. azibense SR-26 should be applied as the most cost-effective option for increasing the yields of legume crops specifically P. vulgaris in salinity-challenged soil systems.

Follicular Becker's nevi: A case series and review of literature.

The follicular variant of Becker's nevus is an under-reported entity. We present the rare occurrence of follicular Becker's nevus in 7 patients, confirmed through dermoscopy and histopathological examination. Dermoscopy shows perifollicular hypopigmentation surrounded by a well-defined net-like pigmentation corresponding clinically to the presence of folliculocentric macules. Histology shows prominent basal and suprabasal melanization surrounding the follicle, corresponding to well-defined net-like pigmentation seen on dermoscopy. However, the melanization does not extend along the entire length of the follicular epithelium leading to perifollicular hypopigmentation on dermoscopy. Though biopsy is confirmatory, it is not usually necessary.

Assessment of upper airway changes after interpositional arthroplasty: a cephalometric analysis.

This prospective cohort study examined the changes in airway area and soft tissue parameters following interpositional arthroplasty for temporomandibular joint (TMJ) ankylosis. Ten patients with TMJ ankylosis underwent surgery, and preoperative and postoperative skeletal and soft tissue measurements were obtained. A significant rise in soft tissue parameters was observed following surgery, although only minor changes in skeletal parameters were seen. The nasoropharyngeal area, oral area, soft palate area, and tongue area were examined. After the surgery, increases in values were observed in the nasoropharyngeal area (from 3482.4 mm2 to 3618.7 mm2), the oral area (from 2731.8 mm2 to 2840.8 mm2), the soft palate area (from 204.9 mm2 to 217.3 mm2), and the tongue area (from 2577.5 mm2 to 2600.8 mm2). These findings suggest that interpositional arthroplasty can improve airway area and soft tissue dimensions, affecting the stomatognathic system's aesthetic and functional aspects. Further research is needed to validate these results and assess long-term stability.

Phytogenically Synthesized Zinc Oxide Nanoparticles (ZnO-NPs) Potentially Inhibit the Bacterial Pathogens: In Vitro Studies.

The usefulness of nanoparticles (NPs) in biological applications, such as nanomedicine, is becoming more widely acknowledged. Zinc oxide nanoparticles (ZnO-NPs) are a type of metal oxide nanoparticle with an extensive use in biomedicine. Here, ZnO-NPs were synthesized using Cassia siamea (L.) leaf extract and characterized using state-of-the-art techniques; UV-vis spectroscopy, XRD, FTIR, and SEM. At sub-minimum inhibitory concentration (MIC) levels, the ability of ZnO@Cs-NPs to suppress quorum-mediated virulence factors and biofilm formation against clinical MDR isolates (Pseudomonas aeruginosa PAO1 and Chromobacterium violaceum MCC-2290) was tested. The ½MIC of ZnO@Cs-NPs reduced violacein production by C. violaceum. Furthermore, ZnO@Cs-NPs sub-MIC significantly inhibited virulence factors such aspyoverdin, pyocyanin, elastase, exoprotease, rhamnolipid, and the swimming motility of P. aeruginosa PAO1 by 76.9, 49.0, 71.1, 53.3, 89.5, and 60%, respectively. Moreover, ZnO@Cs-NPs also showed wide anti-biofilm efficacy, inhibiting a maximum of 67 and 56% biofilms in P. aeruginosa and C. violaceum, respectively. In addition, ZnO@Cs-NPs suppressed extra polymeric substances (EPS) produced by isolates. Additionally, under confocal microscopy, propidium iodide-stained cells of P. aeruginosa and C. violaceum show ZnO@Cs-NP-induced impairment in membrane permeability, revealing strong anti-bacterial efficacy. This research demonstrates that newly synthesized ZnO@Cs-NPs demonstrate a strong efficacy against clinical isolates. In a nutshell, ZnO@Cs-NPs can be used as an alternative therapeutic agent for managing pathogenic infections.

Support vector regression-based model for phenol adsorption in rotating packed bed adsorber.

The excessive strength of phenol present in industrial wastewater is a major issue of concern to be looked upon. Among the pollutant removal techniques, a novel robust device, the rotating packed bed (RPB) adsorber, offers efficient adsorption of phenol due to its ability to magnify the mass transfer rate. In the present study, support vector regression (SVR) has been applied to predict adsorption of phenol on activated carbon in RPB by taking into account the independent parameters, namely, spray density, gravity factor, concentration, and contact time. The experimental data set of phenol adsorption sample has been randomized and normalized prior to constructing the models. The predictive ability of the SVR model has been compared with other data-driven models like artificial neural network (ANN) and multiple regression (MR) models. Both the SVR-based model and the ANN model have almost similar prediction efficacy; however, the ANN model was found to predict the outputs slightly better. The coefficient of determination (R2) and root mean square error (RMSE) values of test data set for the MR RPB adsorption model were found to be 0.934 and 0.149, while for the SVR and ANN-based models, these values were 0.996 and 0.045 and 0.998 and 0.027, respectively. Thus, it was concluded that the soft computing SVR and ANN models possessed tremendous potential to predict the adsorption process of RPB with remarkable accuracy and were greatly generalized.

gPROMS-driven modeling and simulation of fixed bed adsorption of heavy metals on a biosorbent: benchmarking and case study.

Adsorptive separation of heavy metals from wastewater is a viable approach to reuse it and avoid environmental pollution. The productive employment of adsorptive separation at a commercial scale, however, relies on the optimized conditions of an adsorber bed holding maximum and selective isolation of the heavy metals. The experimental route includes a significant trial and error approach, is time-consuming, involves operating cost, and remains economically unattractive. Contrarily, simulation of a mathematical model mimicking the adsorption system along with experimental validation can significantly minimize optimization efforts and suggests the best conditions of separation. In this work, a convective-dispersive model and adsorption model for fixed bed adsorption of copper (Cu), chromium (Cr), and cadmium (Cd) metals over wheat bran biosorbent are simulated using the gPROMS tool for benchmarking. The influence of feed flow rate, bed height, and metal concentration is studied, and breakthrough profiles of all heavy metals are predicted and matched with the literature. The error values (R2 and RMSE) and Chi-squared values determined from gPROMS simulations matched well with the previously available MATLAB-simulated data. After a successful benchmarking, we modeled pilot-scale adsorption of Cr on coconut coir (or Biosorbent) in a gPROMS simulation environment. A detailed method and algorithm of gPROMS simulation for Cr isolation is provided. The influence of feed flow rate, bed height, and initial metal concentration is studied on the breakthrough curves of the Cr. The optimum operating condition for the pilot-scale isolation of Cr from the water is suggested. The parameters, such as the axial dispersion coefficient and distribution coefficient, are determined.

A Review of the Latest Advances in Nanoparticle-Mediated Processes for Hexavalent Chromium Remediation from Water Bodies.

Hexavalent chromium (Cr(VI)) is a well-known carcinogen, and hence its removal from aqueous media is an important area of research in the field of environmental engineering. Adsorptive removal and catalytic reduction are the two most common techniques applied for this purpose. In this regard, nanoparticle-mediated technology has contributed significantly. In the current review article, a systematic investigation has been carried out to find the latest developments that took place in the domain of Cr(VI) removal by nanotechnology. The major portion deals with the advancement and application of the new-age materials, such as carbon nanotubes (CNTs), g-C3N4, MXenes, zero-valent iron (ZVI), and their composites, for the Cr(VI) remediation purpose. Various interesting mechanisms, as proposed by different research groups, have been covered. Applications of the nanocomposites in the real wastewater scenario have also been highlighted. Different characterization techniques often conducted in order to get insight into Cr(VI) removal process have been mentioned. Some patents related to this field have been discussed. Lastly, the future scope of the nanomaterials, current challenges, feasibility of using these nanomaterials in large-scale treatment plants, etc., have been addressed before concluding the article.

Adsorptive removal of Pb(II) using nanostructured γ-alumina in a packed bed adsorber: Simulation using gPROMS.

In this work, convective-dispersive and pore volume and surface diffusion models have been used to analyze Pb(II) adsorption from an aqueous solution over a nanostructured γ-alumina adsorbent in a packed bed adsorber. The models encompassing partial differential equation and a linear algebraic equation coupled with isotherm have been simulated in gPROMS using the backward finite difference approach. The predicted breakthrough curves of Pb(II) adsorption concerning flow rate, initial metal concentration, and bed height were matched with the experimental data. The accuracy of model predictions was analyzed through statistical measures such as coefficient of determination (R2), root mean square error, and chi-squared value. The simulation results also predicted the axial dispersion, distribution coefficient, mass transfer coefficient, pore volume, and surface diffusion coefficient, which are, otherwise, difficult to measure experimentally and, in turn, have been used to assess the mass transfer characteristics of continuous Pb(II) adsorption. Additionally, the values of breakthrough time, exhaustion time, adsorption column capacity, and mass transfer zone were determined as a function of flow rate, bed height, and initial metal concentration. Surface and pore volume diffusions (10-11-10-10 m2/s) apparently controlled the continuous adsorption process, with surface diffusion being dominant. The transport parameters evaluated in the current study could be beneficial for the large-scale Pb(II)/nanostructured γ-alumina adsorption system. As evident from the successful simulation, the developed gPROMS program can also be applied to other adsorbate/adsorbent systems with a slight modification concerning the operating parameters.

Nano-pesticidal potential of Cassia fistula (L.) leaf synthesized silver nanoparticles (Ag@CfL-NPs): Deciphering the phytopathogenic inhibition and growth augmentation in Solanum lycopersicum (L.).

Plant-based synthesis of silver nanoparticles (Ag-NPs) has emerged as a potential alternative to traditional chemical synthesis methods. In this context, the aim of the present study was to synthesize Ag-NPs from Cassia fistula (L.) leaf extract and to evaluate their nano-pesticidal potential against major phyto-pathogens of tomato. From the data, it was found that particle size of spherical C. fistula leaf synthesized (Ag@CfL-NPs) varied from 10 to 20 nm, with the average diameter of 16 nm. Ag@CfL-NPs were validated and characterized by UV-visible spectroscopy (surface resonance peak λ max = 430 nm), energy dispersive spectrophotometer (EDX), Fourier transform infrared (FTIR), and X-ray diffraction pattern (XRD), and electron microscopy; scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The FTIR spectra verified the participation of various living molecules (aromatic/aliphatic moieties and proteins) in synthesized Ag@CfL-NPs. The anti-phytopathogenic potential of Ag@CfL-NPs was assessed under in vitro conditions. Increasing doses of Ag@CfL-NPs exhibited an inhibitory effect against bacterial pathogen Pseudomonas syringae and 400 µg Ag@CfL-NPs ml-1 caused a reduction in cellular viability, altered bacterial morphology, and caused cellular death Furthermore, Ag@CfL-NPs reduced exopolysaccharides (EPS) production and biofilm formation by P. syringae Additionally, Ag@CfL-NPs showed pronounced antifungal activity against major fungal pathogens. At 400 µg Ag@CfL-NPs ml-1, sensitivity of tested fungi followed the order: Fusarium oxysporum (76%) > R. solani (65%) > Sarocladium (39%). Furthermore, 400 µg Ag@CfL-NPs ml-1 inhibited the egg-hatching and increased larval mortality of Meloidogyne incognita by 82 and 65%, respectively, over control. Moreover, pot studies were performed to assess the efficacy of Ag@CfL-NPs to phyto-pathogens using tomato (Solanum lycopersicum L.) as a model crop. The applied phyto-pathogens suppressed the biological, physiological, and oxidative-stress responsiveness of tomatoes. However, 100 mg Ag@CfL-NPs kg-1 improved overall performance and dramatically increased the root length, dry biomass, total chlorophyll, carotenoid, peroxidase (POD), and phenylalanine ammonia lyase (PAL) activity over pathogens-challenged tomatoes. This study is anticipated to serve as an essential indication for synthesis of efficient nano-control agents, which would aid in the management of fatal phyto-pathogens causing significant losses to agricultural productivity. Overall, our findings imply that Ag@CfL-NPs as nano-pesticides might be used in green agriculture to manage the diseases and promote plant health in a sustainable way.

PGPR Kosakonia Radicincitans KR-17 Increases the Salt Tolerance of Radish by Regulating Ion-Homeostasis, Photosynthetic Molecules, Redox Potential, and Stressor Metabolites.

Among abiotic stresses, salinity is a significant limiting factor affecting agricultural productivity, survival, and production, resulting in significant economic losses. Considering the salinity problem, the goal of this study was to identify a halotolerant beneficial soil bacterium to circumvent salinity-induced phytotoxicity. Here, strain KR-17 (having an irregular margin; a mucoid colony; Gm-ve short rod; optimum temperature, 30°C; pH 7.0; no any pigmentation; showed a positive response to citrate utilization, catalase, starch, sucrose, lactose, and dextrose, etc.) recovered from rhizosphere soils of the potato-cultivating field, tolerated surprisingly a high (18% NaCl; 3.-M concentration) level of salt and identified as Kosakonia radicincitans (Accession No. OM348535). This strain was discovered to be metabolically active, synthesized essential PGP bioactive molecules like indole-3-acetic acid (IAA), siderophore (iron-chelating compounds), ACC deaminase, and ammonia, the quantity of which, however, increased with increasing NaCl concentrations. Here, Raphanus sativus L. (radish) was taken as a model crop to evaluate the adverse impact of NaCl, as well as salinity alleviation by halotolerant K. radicincitans. Salinity-induced toxicity to R. sativus was increased in a dose-dependent way, as observed both in vitro and in vivo conditions. Maximum NaCl levels (15%) demonstrated more extreme harm and considerably reduced the plant's biological features. However, membrane damage, relative leaf water content (RLWC), stressor metabolites, and antioxidant enzymes were increased as NaCl concentration increased. In contrast, halotolerant K. radicincitans KR-17 relieved salinity stress and enhanced the overall performance of R. sativus (L.) by increasing germination efficiency, dry biomass, and leaf pigments even in salt-challenged conditions. Additionally, KR-17 inoculation significantly (p ≤ 0.05) improved plant mineral nutrients (Na, K, Ca, Mg, Zn, Fe, Cu, P, and N). Following inoculation, strain KR-17 enhanced the protein, carbohydrates, root pigments, amino acids (AsA and Lys), lipids, and root alkaloids in R. sativus (L.). Besides these, due to PGPR seed priming in NaCl-stressed/non-stressed conditions, membrane damage, RLWC, stressor metabolites, and antioxidant defense enzymes were dramatically reduced. The strong biofilm-forming capacity of K. radicincitans could result in both in vitro and in vivo colonization under NaCl stress. Conclusively, halotolerant K. radicincitans KR-17 may probably be investigated affordably as the greatest way to increase the production of radish under salinity-stressed soils.

Bacillus mojavensis, a Metal-Tolerant Plant Growth-Promoting Bacterium, Improves Growth, Photosynthetic Attributes, Gas Exchange Parameters, and Alkalo-Polyphenol Contents in Silver Nanoparticle (Ag-NP)-Treated Withania somnifera L. (Ashwagandha).

Discharge of nanoparticles (NPs) into aquatic and terrestrial ecosystems during manufacturing processes and from various commercial goods has become a significant ecotoxicological concern. After reaching soil systems, NPs cause deleterious effects on soil fertility, microbial activity, and crop productivity. Taking into consideration the medicinal importance of Withania somnifera (L.) (ashwagandha), the present study assessed the potential hazards of silver nanoparticles (Ag-NPs) and the toxicity amelioration by a metal-tolerant plant growth-promoting rhizobacterium (PGPR). Bacillus mojavensis BZ-13 (NCBI accession number MZ950923) recovered from metal-polluted rhizosphere soil, tolerated an exceptionally high level of Ag-NPs. The growth-regulating substances synthesized by B. mojavensis were increased with increasing concentrations (0-1000 µg mL-1) of Ag-NPs. Also, strain BZ-13 had the ability to form biofilm, produce alginate and exopolysaccharides (EPSs), as well maintain swimming and swarming motilities in the presence of Ag-NPs. Soil application of varying concentrations of Ag-NPs resulted in a dose-related reduction in growth and biochemical features of ashwagandha. In contrast, following soil inoculation, B. mojavensis relieved the Ag-NPs-induced phytotoxicity and improved plant productivity. Root, shoot length, dry biomass, and leaf area increased by 13, 17, 37, 25%, respectively, when B. mojavensis was applied with 25 mg/kg Ag-NPs when compared to noninoculated controls. Furthermore, the soil plant analysis development (SPAD) index, photosystem efficiency (Fv/Fm), PS II quantum yield (FPS II), photochemical quenching (qP), non-photochemical quenching (NpQ), and total chlorophyll and carotenoid content of BZ-13-inoculated plants in the presence of 25 mg Ag-NPs/kg increased by 33, 29, 41, 47, 35, 26, and 25%, respectively, when compared to noninoculated controls that were exposed to the same amounts of NPs. In addition, a significant (p ≤ 0.05) increase in 48, 18, 21, and 19% in withaferin-A (alkaloids), flavonoids, phenols, and tannin content, respectively, was recorded when plants were detached from bacterized and Ag-NP-treated plants. Leaf gas exchange parameters were also modulated in the case of inoculated plants. Furthermore, bacterial inoculation significantly decreased proline, lipid peroxidation, antioxidant enzymes, and Ag-NP's absorption and build-up in phyto-organs. In conclusion, soil inoculation with B. mojavensis may possibly be used as an alternative to protect W. somnifera plants in soil contaminated with nanoparticles. Therefore, phytohormone and other biomolecule-synthesizing and NP-tolerant PGPR strains like B. mojavensis might serve as an agronomically significant and cost-effective remediation agent for augmenting the yield and productivity of medicinally important plants like ashwagandha raised in soil contaminated with nanoparticles in general and Ag-NPs in particular.

Physiological and oxidative stress responses of Solanum lycopersicum (L.) (tomato) when exposed to different chemical pesticides.

Pesticide overuse can have negative effects on developmental processes of non-target host plants. By increasing reactive oxygen species (ROS) levels, pesticides negatively affect cellular metabolism, biochemistry and physiological machinery of plants. Considering these problems, the current study was planned to assess the effect of three different groups of pesticides, namely diazinon (DIZN), imidacloprid (IMID) and mancozeb (MNZB) on Solanum lycopersicum L. (tomato). In general, pesticides resulted in a progressive decrease in physiological and biometric parameters of S. lycopersicum (L.), which varies significantly among concentrations and species of pesticides. Among them, 200 µgMNZB mL-1 had the most severe negative impact and reduced germination rate, root biomass, chl a, chl b, total chlorophyll and carotenoids by 62, 87, 90, 88, 92 and 90%, respectively. In addition, higher doses of pesticides greatly reduced the flowering, fruit attributes and lycopene content. Furthermore, plants exposed to 200 µgDIZN mL-1 showed a progressive drop in root cell viability (54% decrease), total soluble sugar (TSS) (64% decrease) and total soluble protein (TSP) (67% decrease) content. Data analysis indicated that greater doses of pesticides dramatically raised ROS levels and induced membrane damage through production of thiobarbituric acid reactive substances (TBARS), as well as increased cell injury. To deal with pesticide-induced oxidative stress, plants subjected to greater pesticide dosages, showed a substantial increase in antioxidant levels. For instance, ascorbate peroxidase (APX), catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) and guaiacol peroxidase (GPX) were maximally increased by 48, 93, 71, 52 and 94%, respectively following 200 µgMNZB mL-1 soil exposures. Additionally, under a confocal laser scanning microscope (CLSM), pesticide exposed S. lycopersicum (L.) roots stained with 2',7'-dichlorodihydrofluorescein diacetate (2'7'-DCF) and 3,3'-diaminobenzidine, exhibited an increased ROS production in a concentration-dependent manner. Further, elevated pesticide concentrations resulted in alterations in mitochondrial membrane potential (ΔΨ m) and cellular death in roots, as evidenced by increased Rhodamine 123 (Rhd 123) and Evan's blue fluorescence, respectively. These findings clearly showed that applying pesticides in excess of permissible amounts might induce oxidative stress and cause oxidative damage in non-target host plants. Overall, the current study indicates that a thorough and secure method be used before selecting pesticides for increasing production of agronomically important vegetable crops in various agro-climatic zones.

Green Synthesized Silver Nanoparticles Mitigate Biotic Stress Induced by Meloidogyne incognita in Trachyspermum ammi (L.) by Improving Growth, Biochemical, and Antioxidant Enzyme Activities.

Meloidogyne incognita is an important plant-parasitic nematode that causes significant crop losses all over the world. The primary control strategy for this pathogen is still based on nematicides, which are hazardous to human health and the environment. Considering these problems, this study aimed to determine the efficacy of different concentrations (25, 50, and 100 ppm) of silver nanoparticles against M. incognita on Trachyspermum ammi. Silver nanoparticles synthesized from Senna siamea were thoroughly characterized using various physicochemical techniques, viz., UV-visible spectrophotometer, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray analyzer (EDX). Results revealed that plants treated with 50 ppm silver nanoparticles one week before M. incognita inoculation (T2) exhibited maximum and significant (p ≤ 0.05) increases in plant growth, biochemical characteristics, and activities of defense enzymes such as peroxidase, catalase, superoxide dismutase, and ascorbate peroxidase over the inoculated control (IC) plants. Furthermore, the maximum reduction in the number of galls, egg masses, and root-knot indices was recorded in plants treated with 100 ppm silver nanoparticles (T3) followed by plants treated with 50 ppm silver nanoparticles before nematode inoculation (T2), over inoculated plants (IC). Anatomical studies showed accumulation of lignin in the transverse section (TS) of roots treated with 50 ppm silver nanoparticles. As a result, the present finding strongly suggests that silver nanoparticles synthesized from S. siamea had nematicidal activity, and it could be an efficient, safe, cost-effective, and affordable alternative to chemical nematicide.

Application of abscisic acid and 6-benzylaminopurine modulated morpho-physiological and antioxidative defense responses of tomato (Solanum lycopersicum L.) by minimizing cobalt uptake.

A hydroponic study was conducted to determine the effects of single and/or combined application of different doses (0, 5 and 10 µM L-1) of abscisic acid (ABA) and 6-benzylaminopurine (BAP) on cobalt (Co) accumulation, morpho-physiological and antioxidative defense attributes of tomato (Solanum lycopersicum L.) exposed to severe Co stress (400 µM L-1). The single Co treatment (T1), prominently decreased tomato growth, relative water contents, photosynthetic pigments (chlorophyll a and chlorophyll b), whereas enhanced oxidative stress and Co accumulation in shoot and root tissues. Nonetheless, the supplementation of ABA and 6-BAP via nutrient media significantly (P < 0.05) enhanced plant biomass, root morphology and chlorophyll contents of tomato, compared to only Co treatment (T1). Moreover, the oxidative stress indicators such as malondialdehyde, proline and H2O2 contents were ameliorated through activation of enzymatic antioxidant activities i.e. ascorbate peroxidase, superoxide dismutase, catalase, and peroxidase, in growth modulator treatments in comparison to T1. The Co uptake, translocation (TF) and bioaccumulation factor (BAF) by shoot and root tissues of tomato were significantly reduced under all the treatments than that of T1. The supply of 6-BAP alone or in combination with ABA at 10 µM L-1 application (T7) rate was found the most effective to reduce Co accumulation in the roots and shoots by 48.4% and 70.2% respectively than T1 treatment. It can be concluded that two plant growth modulators could improve the stress tolerance by inhibition of Co uptake in tomato plants.