Tolerance and decolorization potential of duckweed (Lemna gibba) to C.I. Basic Green 4

Alkaline protease functionalized hydrothermal synthesis of novel gold nanoparticles (ALPs-AuNPs): A new entry in photocatalytic and biological applications

Researchers are consistently investigating novel and distinctive methods and materials that are compatible for human life and environmental conditions This study aimed to synthesize gold nanoparticles (ALPs-AuNPs) using for the first time an alkaline protease (ALPs) derived from Phalaris minor seed extract. A series of physicochemical techniques were used to inquire the formation, size, shape and crystalline nature of ALPs-AuNPs. The nanoparticles' ability to degrade methylene blue (MB) through photocatalysis under visible light irradiation was assessed. The findings demonstrated that ALPs-AuNPs exhibited remarkable efficacy by destroying 100 % of MB within a mere 30-minute irradiation period. In addition, the ALPs-AuNPs demonstrated remarkable effectiveness in inhibiting the growth of gram-positive (S. aureus) and gram-negative (E. coli) bacteria. The inhibition zones examined against the two bacterial strains were 23(±0.3) mm and 19(±0.4); 13(±0.3) mm and 11(±0.5) mm under light and dark conditions respectively. The ALPs-AuNPs exhibited significant antioxidant activity by effectively scavenging 88 % of stable and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. As a result, the findings demonstrated that the environmentally friendly ALPs-AuNPs showed a strong potential for MB degradation and bacterial pathogen treatment.

Sunlight-induced repair of photosystem II in moss Semibarbula orientalis under submergence stress

Lower plants such as bryophytes often encounter submergence stress, even in low precipitation conditions. Our study aimed to understand the mechanism of submergence tolerance to withstand this frequent stress in moss (Semibarbula orientalis ) during the day and at night. These findings emphasise that light plays a crucial role in photoreactivation of PSII in S. orientalis , which indicates that light not only fuels photosynthesis but also aids in repairing the photosynthetic machinery in plants. Submergence negatively affects photosynthesis parameters such as specific and phenomenological fluxes, density of functional PSII reaction centres (RC/CS), photochemical and non-photochemical quenching (Kp and Kn), quantum yields (ϕP0 , ϕE0 , ϕD0 ), primary and secondary photochemistry, performance indices (PIcs and PIabs), etc. Excessive antenna size caused photoinhibition at the PSII acceptor side, reducing the plastoquinone pool through the formation of PSII triplets and reactive oxygen species (ROS). This ROS-induced protein and PSII damage triggered the initiation of the repair cycle in presence of sunlight, eventually leading to the resumption of PSII activity. However, ROS production was regulated by antioxidants like superoxide dismutase (SOD) and catalase (CAT) activity. The rapid recovery of RS/CS observed specifically under sunlight conditions emphasises the vital role of light in enabling the assembly of essential units, such as the D1 protein of PSII, during stress in S. orientalis . Overall, light is instrumental in restoring the photosynthetic potential in S. orientalis growing under submergence stress. Additionally, it was observed that plants subjected to submergence stress during daylight hours rapidly recover their photosynthetic performance. However, submergence stress during the night requires a comparatively longer period for the restoration of photosynthesis in the moss S. orientalis .

Impact of mercury on photosynthetic performance of Lemna minor: a chlorophyll fluorescence analysis

The purpose of this study was to evaluate the effectiveness of chlorophyll fluorescence analysis in detecting the effects of mercury (Hg) treatment in duckweed species Lemna minor. The results showed that Hg treatment (ranging from 0.0 to 0.4 µM) significantly impacted the plant's photosynthetic ability, with a decrease in variable chlorophyll fluorescence, energy fluxes, density of reaction centers, and performance index. Complete inhibition of electron transport was observed in plants treated with high Hg concentrations, and the quantum yield of primary photochemistry and the ratio of dissipated energy to absorption both decreased with increasing Hg concentrations. Performance Index (PI) was significantly affected by the Hg concentrations, reaching zero in plants treated with the highest Hg concentration. Overall, JIP analysis was found to be an effective tool for detecting deleterious effects of Hg in plants.

Balanites aegyptiaca leaf extract-mediated synthesis of silver nanoparticles and their catalytic dye degradation and antifungal efficacy

This study describes the biosynthesis of silver nanoparticles (AgNPs) using Balanites aegyptiaca (B. aegyptiaca) leaf extract. The biosynthesized AgNPs were characterized by UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy with (SEM-EDS). The AgNPs showed an average size of 10–20 nm, spherical shape, and crystalline nature. The application of these synthesized AgNPs to dye degradation showed that the AgNPs removed the two organic pollutants methylene blue (MB, 93.47%) and congo red (CR, (78.57%). In vitro investigation of the antifungal activity of the AgNPs against Fusarium oxysporum, a phytopathogenic fungus, showed a maximum percent radial growth inhibition of 82.00 ± 1.00% and a spore percent inhibition of 73.66 ± 3.94 for 150 μg/ml of biosynthesized AgNPs.

Phyto-fabrication of silver nanoparticles and their catalytic dye degradation and antifungal efficacy

The biogenic synthesis of silver nanoparticles (AgNPs) and their potent application against dye degradation and phytopathogens are attracting many scientists to nanotechnology. An attempt was made to synthesize silver nanoparticles using Plantago ovata leaf extract and test their effectiveness in removing organic dyes and antifungal activity. In the present study, stable AgNPs were synthesized from 0.1 mM AgNO₃ and authenticated by observing the color change from yellow to red-brown, which was confirmed with wavelength UV-Vis spectrophotometer detection. The crystalline nature of the particles was characterized by x-ray diffraction (XRD) patterns. Furthermore, the AgNPs were characterized by high-resolution transmission electron microscope and scanning electron microscope investigations. Atomic force microscopy (AFM) and Raman spectra were also used to confirm the size and structure of the synthesized AgNPs. The elemental analysis and functional groups responsible for the reduction of AgNPs were analyzed by electron dispersive spectroscopy and fourier transform infra-red spectroscopy Fourier transforms infrared, respectively. A new biological approach was taken by breaking down organic dyes such as methylene blue and congo red. The AgNPs effectively inhibit the fungal growth of Alternaria alternata. This could be a significant achievement in the fight against many dynamic pathogens and reduce dye contamination from waste water.

Synthesis of silver nanoparticles employing Polyalthia longifolia leaf extract and their in vitro antifungal activity against phytopathogen

The P. longifolia mediated silver (PL-AgNPs) nanoparticles are very stable and efficient. UV–Vis spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDX) were used to characterize the produced AgNPs. UV–Vis analysis showed a characteristic peak at 435 nm corresponding to surface plasmon resonance. The synthesis process was spectrophotometrically optimized for various parameters. After optimization, highly stable AgNPs were prepared using 3.0 ml of P. longifolia leaf extract, pH 7.0, 1.0 mM AgNO₃, and 60 °C. The zeta potential was measured by DLS, which showed −20.8 mV and the PDI value was 5.42. TEM and SEM analysis shows a spherical shape of the synthesized nanoparticles, and the size was measured between 10 and 40 nm. EDX analysis showed intense peaks from silver and oxygen and small peaks from various metal atoms such as Na, P, S and Al indicating their presence in trace amounts. The average size of the PL-AgNPs was 14 nm. The phytochemical analysis shows that the presence of alkaloids, essential oils and saponins seems to be responsible for the synthesis of nanoparticles. PL-AgNPs were further investigated for their antifungal activity against Alternaria alternata. The minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC) and effect of nanoparticles on cytomorphology of A. alternata have also been reported. Biosynthesized nanoparticles have proven to be inexpensive, environmentally friendly, stable, easily reproducible, and highly effective against plant-pathogenic fungi.

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Green synthesis of AgNPs using aqueous leaf extract of Polyalthia longifolia.

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Characterization using UV–vis, DLS, XRD, TEM, SEM, EDX.

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Optimization of AgNPs at different Temperature, pH, Concentration and Time.

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Nanoparticles were stable for more than 5 months.

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The antifungal activity of the AgNPs against A. alternata were studied.

Ultrastructure, adaptability, and alleviation mechanisms of photosynthetic apparatus in plants under waterlogging: A review

Photosynthesis is a process highly sensitive to various abiotic and biotic stresses in plants. Among them, the major abiotic stress, waterlogging, affects the crop's growth and productivity. Under waterlogging, the photosynthetic apparatus of plants was destroyed. Waterlogging reduced chlorophyll content and the net photosynthetic rate. Therefore, this updated review summarized the effect of waterlogging on chloroplast ultrastructure, photosynthetic characteristics, and chlorophyll fluorescence attributes of plant species. By studying various research papers, we found that intercellular concentration of available carbon dioxide in mesophyll cells, assimilation of carbon, and the net photosynthetic ratio declined under waterlogging. The chlorophyll fluorescence efficiency of plants decreased under waterlogging. Thus, the study of photosynthesis in plants under waterlogging should be done with respect to changing climate. Moreover, the recognition of photosynthetic characteristics present in tolerant species will be beneficial for designing the waterlogging-tolerant crop plant in changing environments.

Performance of chlorophyll a fluorescence parameters in Lemna minor under heavy metal stress induced by various concentration of copper

The objective of the present investigation was to understand the efficacy of chlorophyll fluorescence analysis and to identify the specific photosynthetic parameters for early and rapid detection of Cu-induced HM-stress in plants. Aquatic angiosperm Lemna minor was exposed to various concentrations (0-40 µM) of Cu. We observed that the F_V/F_O (Efficiency of the water-splitting complex on the donor side of PSII), quantum yield for electron transport, and quantum yield of primary photochemistry were decreased however, dissipated quantum yield was increased with Cu concentration. ABS/CS_M, TR_O/CS_M, ET_O/CS_M and maximum quantum yield were displayed the dose-response relationship under Cu stress. Performance indexes were increased initially due to the beneficial effects of Cu at lower concentration while decreased significantly (p ≤ 0.05) at highest concentration of Cu. The outcomes of the present research revealed that the ChlF analysis is very sensitive tool that can be used to determine the toxicity of heavy metals in plants.

Effect of different waterlogging periods on biochemistry, growth, and chlorophyll a fluorescence of Arachis hypogaea L

Peanut is among the main oil crops in India with huge economic importance. The unpredictable rainy season during the growing time of peanuts causes waterlogging in peanut fields. Waterlogging triggers major environmental limitations that negatively affect the growth, physiology, and development of peanuts. Thus, the export and production of peanuts are severely affected by waterlogging. Therefore, the understanding of metabolic mechanisms under waterlogging is important to future water-stress tolerance breeding in peanuts. This study aimed to evaluate how peanuts responded to various waterlogging conditions in terms of their development, metabolic processes, and chlorophyll fluorescence characteristics. The evaluations were carried out at different stages of peanut variety DH-86 treated with waterlogging. The peanut plants were subjected to different waterlogging periods of 20, 40, 60, 80, and 100 days. The growth parameters including total dry mass, total leaf area, and total leaves number were calculated in all treatments. The phenomenological and specific energy fluxes and maximum photosystem II efficiency (F_V/Fm) were also determined. The measurements were done statistically using PCA, G-Means clustering, and correlation analysis to explore the interaction between different physiological parameters. The waterlogging for 100 days caused a significant reduction in the total number of leaves, dry mass, and total leaf area. The most sensitive parameters are specific and phenomenological energy fluxes and Fv/Fm, which notably decreased as waterlogging duration increased. The results indicated the growth and physiological performance of the peanut cv. DH-86 was affected significantly due to waterlogging and the interaction between all these parameters in waterlogging. This research focused on how peanuts respond to waterlogging stress and provides the basis for future plant breeding efforts to improve peanut waterlogging tolerance, especially in rainy regions. This will improve the sustainability of the entire peanut industry.