Chemically synthesized silver nanoparticles (AgNP) have been assessed on plant tissue cultures but the impact of biologically synthesized AgNP fabricated by different phytoconstituents has not been ...sufficiently investigated. In this study biogenic AgNP prepared from leaf extract of
Swertia chirata
was utilized to address the problems associated with conservation of endangered medicinal plant through plant tissue culture. Endangered as well as economically important medicinal plant considered for this analysis was the same plant
S. chirata
itself. Excessive deforestation and exploration of this plant had led to complete eradication of the natural reservoir. Thus in vitro plant tissue propagation had attained much importance for maintaining the plant species. Nano-sized particles of diameter 20 nm encapped by different phytochemicals applied on regenerating shoot cultures showed enhanced shoot induction and proliferation. Other forms of silver like AgNO
3
(SN) and Ag
2
S
2
O
3
(STS) showed improved regeneration in comparison to control samples. Ethylene precursors like 1-aminocyclopropane-1-carboxylic acid (ACC) and 2-chloroethylphosphonic acid (CEPA) downregulated the regeneration process considerably. Reactive oxygen species (ROS) status of the treated cultures were evaluated considering hydrogen peroxide and malondialdehyde (MDA) content in treated cells as wells as their antioxidant enzyme activity. Combined manipulation and coordination of ethylene evolution, maintenance of ROS balance and better bio-acceptance of AgNP were responsible for improvement in shoot regeneration of the plant. Phytoencapsulated and nano-dimensioned Ag was capable of changing the chemical reactions of different regulating players of plant regeneration. These findings will facilitate the understanding and future utilization of biofabricated AgNP in agriculture and plant sciences.
The knowledge on the mode of action, biocompatibility and ecological tolerance of silver nanoparticles (AgNPs) is gradually accumulating over the years with contradictory findings. Most of the ...studies indicated the toxic impact of AgNPs on plant growth and development, where induction of oxidative stress was considered to be one of the causal factors. The present study demonstrates the phytostimulatory effect of bio-synthesized silver nanoparticles (AgNPs) during seed germination and seedling growth of rice (Oryza sativa L., cv. Swarna) under in vitro condition. All the tested concentrations of AgNPs (10, 20, 40 ppm) promote both the shoot and root growth which was evident from the increased length and biomass of the seedlings. Exposure to AgNPs also significantly increased the chlorophyll a and carotenoid contents. The content and the pattern of distribution of phenolic metabolites among the different treatments are indicative of non-toxic impact of AgNP mimicking mild or no stress to the seedlings. Growth stimulation of rice seedlings by AgNPs was further supported by a low level of reactive oxygen species (ROS) concomitant with decreased amount of lipid peroxidation and H2O2 content, compared to control. In order to unravel the stimulatory impact of AgNPs on rice seedling growth, the present study also describes the AgNPs induced changes in antioxidative enzyme activity and related gene expression levels. Elevated levels of catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) activities were recorded in all the AgNPs treated seedlings with improved growth. The activity of superoxide dismutase (SOD) was not significantly altered at low concentration of AgNPs. It appears that enzymes of ascorbate cycle, APX and GR are more active in ensuring protection against oxidative damage than SOD. There was significant up-regulation of CAT and APX gene expressions in seedlings exposed to AgNPs, whereas the expression level of CuZnSOD gene was decreased gradually with an increase in the concentration of AgNPs. The antioxidant enzyme activities and gene expression patterns coupled with the levels of H2O2 and lipid peroxidation indicates that the efficiency of redox reactions was increased in the presence of AgNPs and that accelerates the seedling growth.
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•Bio-synthesized silver nanoparticles (AgNPs) promoted the growth of rice seedlings.•A low level of ROS with decreased amount of lipid peroxidation and H2O2 content was found in AgNP treated seedlings.•Exposure to AgNPs elevated the activities of CAT, APX and GR.•CAT and APX genes were up-regulated, whereas expression of SOD gene was decreased in seedlings exposed to AgNPs.•An efficient redox balance induced by AgNPs may account for the improved growth of rice seedlings.
•Toxic effect of low-dose biosynthesized nanoparticles were studied.•Silver nanoparticles (AgNPs) were biosynthesized using Swertia chirata.•Mitotic and meiotic indexes decreased with increasing ...concentrations of AgNPs.•Different chromosomal aberrations were observed in AgNPs treated A. cepa cells.•Biogenic AgNPs are less toxic than chemically synthesized AgNPs.
Chemically synthesized silver nanoparticles (chem-AgNPs) have been assessed extensively to show adverse effects on plant cells but the role of biologically synthesized nanoparticles (bio-AgNPs) at lower concentrations and their toxicological impact on plant cells have not been sufficiently studied. In this study, bio-AgNPs were prepared using aqueous leaf extracts of Swertia chirata. This AgNPs showed absorption peak at 440nm of the visible spectrum. TEM analysis revealed that the average size of AgNPs were 20nm and mainly spherical in shape. AFM topographic images depicted the three dimensional aspects of AgNPs. XRD analysis confirmed the crystalline nature. FTIR spectrum of the AgNPs revealed the possible biomolecules involved in bioreduction and efficient stabilization of the particles. Low-dose of bio-AgNPs concentrations (5, 10 and 20μgml−1) were used for toxicity studies on Allium cepa. The studies revealed that various chromosomal aberrations were induced in both mitotic and meiotic cells of Allium cepa even at lower concentrations of bio-AgNPs. Abnormalities in post meiotic products were also observed. Both mitotic and meiotic indexes decreased with increasing concentrations of bio-AgNPs in the treated cells. These findings implied that low dose bio-AgNPs can induce significant clastogenic effects on both meristematic and reproductive plant cells.
The present study demonstrates the influence of LED irradiance of various wavelengths on shoot regeneration, biomass accumulation, photosynthetic pigment contents, and antioxidant potentials of ...Swertia chirata - a critically endangered medicinal plant. Mixed treatment of blue (BL) and red LEDs (RL) in equal proportion (1:1) significantly improved the shoot regeneration response. A machine vision system was developed to assess the shoot regeneration potential under different lighting treatments. Regenerated shoots exposed under BL:RL (1:1) exhibited higher biomass accumulation and canopy development compared to other lighting treatments. Improved canopy growth was evident from the increase in the area, major axis, minor axis, convex area, equivalent diameter and perimeter of regenerated shoot clusters. A higher correlation of dry weight (DW) was noted with the image feature, weighted density (WD) than the fresh weight (FW) in all the LED treated cultures. The significant correlation between DW and WD implies that the image feature WD can be adopted as a non-invasive approach for measuring biomass accumulation as well as detecting hyperhydricity. The developed machine vision approach provides a new direction in the evaluation of shoot organogenesis that displayed features including both shoot multiplication and canopy development. Chlorophyll and carotenoid contents of the regenerated shoots were found to be higher under BL:RL (1:1) than the other treatments. Supplementation of RL led to a reduction in the pigment contents. Spectral quality of lights also significantly influenced the accumulation of total phenolics, flavonoids and flavonols. Cultures exposed under BL exhibited the maximum accumulation of polyphenols. A similar effect of spectral quality was observed with the antioxidant capacity and reducing power potential of leaf extract. The findings demonstrate the ability of LEDs in inducing shoot regeneration as well as accumulation of phenolic antioxidants and suggest that the proportion of blue and red LEDs is an important factor in achieving the optimum response.
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•LED irradiation has significant influence on in vitro shoot regeneration of Swertia chirata.•A machine vision system was developed with a new direction in the evaluation of shoot regeneration.•Spectral quality of lights also significantly influenced the accumulation of phytochemicals.•The proportion of blue and red LEDs appeared to be an important factor for optimum response.•Mixed LED treatment of BL:RL (1:1) was the most promising light source.
Advances in plant tissue culture methods with regard to lighting requirements are currently focused on the improved features of light-emitting diodes (LEDs). Over the years, the steady development of ...LED technology, with the emergence of new types of semi-conductor materials, has made it possible to apply it in an increasing number of new areas. As an alternative to conventional lighting systems, LED has been demonstrated to be an artificial flexible lighting source for plant tissue culture. Numerous studies have been conducted in order to investigate the effects of LED on plants, which have led to many satisfactory results. Various morphological, anatomical, and physiological attributes, such as shoot elongation, axillary shoot formation, somatic embryo induction, rhizogenesis, leaf anatomy, and photosynthetic abilities of plants grown in vitro have found to be regulated by spectral properties of LEDs. The present review gives an overview of the fundamentals of LEDs and describes their effects on in vitro plant growth and morphogenesis and their future potentials.
Susceptibility to damage from heat and flame is one of the major issues for utilisation of natural fibre reinforced polymeric composites in practical applications. Thus, the knowledge of thermal ...decomposition and flammability of the bio-based fibres, polymers and their composites is highly required for the materials selection and the development of composite products. Moreover, suitable flame retardant treatments on these composites have shown to effectively enhance their thermal stability and fire resistance. This article provides a review of research on thermal behaviour and flammability of natural fibres, such as cellulose and protein based fibres, and polymers along with composites filled with these materials. Furthermore, eco-friendly flame retardant treatments to overcome the environmental impact of conventional flame retardants are introduced with the combined effects of natural fibres on composites' fire performance. In addition, a review of studies on the predictive models regarding thermal response and structural damages of composites in fire is also included with their advantages and limitations.
Purpose:
To investigate whether the sperm concentration of European men is deteriorating over the past 50 years of time.
Materials and Methods:
We analysed the data published in English language ...articles in the past 50 years in altering sperm concentration in European men.
Results:
A time-dependent decline of sperm concentration (r = −0.307, p = 0.02) in the last 50 years and an overall 32.5% decrease in mean sperm concentration was noted.
Conclusion:
This comprehensive, evidence-based meta-analysis concisely presents the evidence of decreased sperm concentration in European male over the past 50 years to serve the scientific research zone related to male reproductive health.
A method has been developed for rapid and non invasive determination of chlorophyll content of leaves of micropropagated potato plants using RGB based image analysis. Among the trichomatic colors, R ...and G negatively correlated with the chlorophyll content, while a positive correlation was observed with B chromate. Compared to mean brightness value, the use of mean brightness ratio considerably improved the relationship of the tricolors with chlorophyll content. The brightness values and ratios of the primary colors are modeled as linear correlation functions for chlorophyll content. A significant correlation was observed between the model predicted chlorophyll content with the chlorophyll content measured by chlorophyll content meter. Spectral properties such as luminosity and saturation were also found to be negatively correlated with the chlorophyll content. The relationship was improved by combining the mean brightness ratio at B band region with luminosity. The potential of the imaging system in micropropagation has been discussed.
Recently a conformally invariant action describing the Wilson-Fisher fixed point in D=4−ϵ dimensions in the presence of a finite UV cutoff was constructed 44. In the present paper we construct two ...composite operator perturbations of this action with definite scaling dimension also in the presence of a finite cutoff. Thus the operator (as well as the fixed point action) is well defined at all momenta 0≤p≤∞ and at low energies they reduce to ∫xϕ2 and ∫xϕ4 respectively. The construction includes terms up to O(ϵ2). In the presence of a finite cutoff they mix with higher order ∫xϕn operators. The dimensions are also calculated to this order and agree with known results.
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