Optimizing biochar, vermicompost, and duckweed amendments to mitigate arsenic uptake and accumulation in rice (Oryza sativa L.) cultivated on arsenic-contaminated soil.

The accumulation of arsenic (As) in rice (Oryza sativa L.) grain poses a significant health concern in Bangladesh. To address this, we investigated the efficacy of various organic amendments and phytoremediation techniques in reducing As buildup in O. sativa. We evaluated the impact of five doses of biochar (BC; BC0.1: 0.1%, BC0.28: 0.28%, BC0.55: 0.55%, BC0.82: 0.82% and BC1.0: 1.0%, w/w), vermicompost (VC; VC1.0: 1.0%, VC1.8: 1.8%, VC3.0: 3.0%, VC4.2: 4.2% and VC5.0: 5.0%, w/w), and floating duckweed (DW; DW100: 100, DW160: 160, DW250: 250, DW340: 340 and DW400: 400 g m- 2) on O. sativa cultivated in As-contaminated soil. Employing a three-factor five-level central composite design and response surface methodology (RSM), we optimized the application rates of BC-VC-DW. Our findings revealed that As contamination in the soil negatively impacted O. sativa growth. However, the addition of BC, VC, and DW significantly enhanced plant morphological parameters, SPAD value, and grain yield per pot. Notably, a combination of moderate BC-DW and high VC (BC0.55VC5DW250) increased grain yield by 44.4% compared to the control (BC0VC0DW0). As contamination increased root, straw, and grain As levels, and oxidative stress in O. sativa leaves. However, treatment BC0.82VC4.2DW340 significantly reduced grain As (G-As) by 56%, leaf hydrogen peroxide by 71%, and malondialdehyde by 50% compared to the control. Lower doses of BC-VC-DW (BC0.28VC1.8DW160) increased antioxidant enzyme activities, while moderate to high doses resulted in a decline in these activities. Bioconcentration and translocation factors below 1 indicated limited As uptake and translocation in plant tissues. Through RSM optimization, we determined that optimal doses of BC (0.76%), VC (4.62%), and DW (290.0 g m- 2) could maximize grain yield (32.96 g pot- 1, 44% higher than control) and minimize G-As content (0.189 mg kg- 1, 54% lower than control). These findings underscore effective strategies for enhancing yield and reducing As accumulation in grains from contaminated areas, thereby ensuring agricultural productivity, human health, and long-term sustainability. Overall, our study contributes to safer food production and improved public health in As-affected regions.

A novel multitrophic biofloc technology for duckweed and Megalobrama amblycephala integrated culture: Improving nutrient utilization and animal welfare.

Biofloc technology (BFT) is an eco-friendly aquaculture model that utilizes zero-exchange water. In this study, we investigated the integration of duckweed into BFT in an effort to enhance nitrogen, phosphorus, and carbon utilization and to improve animal welfare for cultivating Megalobrama amblycephala. The experiment spanned 75 days, comparing a group of M. amblycephala supplemented with duckweed (DM) to a control group (CG) with no supplementation, where duckweed consumption relied solely on the feeding behavior of the fish. The concentrations of nitrate, total nitrogen, and phosphorus accumulation were lower in the DM than in the CG from day 45 onwards, with differences of 16.19, 26.90, and 1.45 mg/L, respectively, at the end of the experiment. The DM showed simultaneous increases of 5.77, 11.20, and 5.07 % in the absolute utilization of nitrogen, phosphorus, and carbon, respectively. The abundance of TM7a (10.27 %), linked to nitrate absorption, became the dominant genus in the water of the DM. Additionally, the abundance of Cetobacterium, associated with carbohydrate digestion, was significantly higher in gut of the DM (23.83 %) than in the gut of CG (1.24 %, P < 0.05). Supplementing the diet of M. amblycephala with duckweed improved digestion and antioxidant enzyme activity. Transcriptome data showed that duckweed supplementation resulted in an increase in the expression of genes related to protein digestion and absorption and carbohydrate metabolism in M. amblycephala, and analysis of the significantly enriched pathways further supported improved antioxidant capacity. Based on the above results, we concluded that as M. amblycephala consumes more duckweed, the differences in nitrogen and phosphorus levels between the DM and CG would continue to increase, along with a simultaneous increase in fixed carbon. Thus, this study achieved the goal of recycling BFT resources and improving animal welfare by integrating duckweed.

Optimization of Hoagland solution macro-elements as a culture media, for increasing protein content of duckweeds (Lemna minor).

This study aimed to increase the protein content of duckweed, a promising alternative to animal proteins and a sustainable source of plant protein cultivated via soilless agriculture, by manipulating the culture medium conditions (Hoagland solution). The contribution percentages of KH2PO4 and Ca(NO3)2, pivotal macro-elements in Hoagland solution affecting duckweed protein content, were determined using Plackett-Burman factorial design as 33.06 % and 36.61 %, respectively. Additionally, optimization was conducted employing response surface methodology, incorporating pH alongside KH2PO4 and Ca(NO3)2. Under optimal conditions of 3.92 mM KH2PO4, 7.95 mM Ca(NO3)2, and 7.22 pH, the protein content of duckweed increased significantly, reaching 51.09 % from 39.81 %. The duckweed cultivated in modified Hoagland solution exhibited protein content of 41.74 %, while duckweed grown in commercial Hoagland solution displayed protein content of 33.01 %. This study showed protein content of duckweed could significantly increase according to the growth medium and showcasing its potential as a sustainable source of plant protein.

In situ phytoextraction of Mn and NH4+-N from aqueous electrolytic manganese residue solution by Pistia stratiotes: Effects of Fe/Co presence and rhizospheric microbe synergistic involvement.

The electrolytic manganese industry produces a large amount of electrolytic manganese residue (EMR). Soluble Mn, NH4+-N, and other pollutants may be released from the open-air stacked EMR and transported to the environment along with rainfall or surface runoff. Aqueous EMR solution (AES) generally contains various elements required for plant growth, and phytoremediation can be applied to remove these pollutants from AES. Since the contents of Fe and Co vary greatly in AES depending on the ore sources as well as the pre-treatment processes, the presence of bioavailable Fe and Co at different levels may affect plant growth, the rhizosphere microbes, and pollutant removal. The present study investigated the in-situ removal of Mn(II) and NH4+-N from AES solution using free floating aquatic plant Pistia stratiotes, focusing especially on the effects of Fe/Co presence and rhizospheric microbe synergistic involvement on contaminant removal. The results showed that 69.08% of Mn and 94.99% of NH4+-N were removed by P. stratiotes in 24 d. Both the presence of Fe(II) and Co(II) facilitated the Mn(II) immobilization and increased Mn(II) removal by 19-31% due to the enhanced peroxidase activity and the increased Mn accumulating in roots The complete removal of Mn from AES was found in the presence of Fe(II) at 2 mg L-1 or Co(II) at 0.5 mg L-1 and more than 51% accumulated Mn in the roots was stored in the vacuole and cytoplasm. BioMnOx was found on the surface of the roots, revealing that rhizofiltration, rhizospheric plaque/biofilm formation, and Mn biogeochemical cycle exert synergic effects on Mn(II) immobilization. The findings of the present study demonstrate the feasibility of using P. stratiotes in the treatment of aqueous EMR solutions and the presence of an appropriate amount of bio-available Fe and Co can promote the removal of Mn(II) and NH4+-N.

Population genomics and epigenomics of Spirodela polyrhiza provide insights into the evolution of facultative asexuality.

Many plants are facultatively asexual, balancing short-term benefits with long-term costs of asexuality. During range expansion, natural selection likely influences the genetic controls of asexuality in these organisms. However, evidence of natural selection driving asexuality is limited, and the evolutionary consequences of asexuality on the genomic and epigenomic diversity remain controversial. We analyzed population genomes and epigenomes of Spirodela polyrhiza, (L.) Schleid., a facultatively asexual plant that flowers rarely, revealing remarkably low genomic diversity and DNA methylation levels. Within species, demographic history and the frequency of asexual reproduction jointly determined intra-specific variations of genomic diversity and DNA methylation levels. Genome-wide scans revealed that genes associated with stress adaptations, flowering and embryogenesis were under positive selection. These data are consistent with the hypothesize that natural selection can shape the evolution of asexuality during habitat expansions, which alters genomic and epigenomic diversity levels.

Changes in Metabolism and Content of Chlorophyll in Common Duckweed (Lemna minor L.) Caused by Environmental Contamination with Fluorides.

The impact of fluorine on plants remains poorly understood. We examined duckweed growth in extracts of soil contaminated with fluorine leached from chicken manure. Additionally, fluorine levels were analyzed in fresh manure, outdoor-stored manure, and soil samples at varying distances from the manure pile. Fresh manure contained 37-48 mg F- × kg-1, while soil extracts contained 2.1 to 4.9 mg F- × kg-1. We evaluated the physiological effects of fluorine on duckweed cultured on soil extracts or in 50% Murashige-Skoog (MS) medium supplemented with fluorine concentrations matching those in soil samples (2.1 to 4.9 mg F- × L-1), as well as at 0, 4, and 210 mg × L-1. Duckweed exposed to fluorine displayed similar toxicity symptoms whether in soil extracts or supplemented medium. Fluoride at concentrations of 2.1 to 4.9 mg F- × L-1 reduced the intact chlorophyll content, binding the porphyrin ring at position 32 without affecting Mg2+. This reaction resulted in chlorophyll a absorption peak shifted towards shorter wavelengths and formation of a new band of the F--chlorophyll a complex at λ = 421 nm. Moreover, plants exposed to low concentrations of fluorine exhibited increased activities of aminolevulinic acid dehydratase and chlorophyllase, whereas the activities of both enzymes sharply declined when the fluoride concentration exceeded 4.9 mg × L-1. Consequently, fluorine damages chlorophyll a, disrupts the activity of chlorophyll-metabolizing enzymes, and diminishes the plant growth rate, even when the effects of these disruptions are too subtle to be discerned by the naked human eye.

Trophic interactions in microbiomes influence plant host population size and ecosystem function.

Plant microbiomes that comprise diverse microorganisms, including prokaryotes, eukaryotes and viruses, are the key determinants of plant population dynamics and ecosystem function. Despite their importance, little is known about how species interactions (especially trophic interactions) between microbes from different domains modify the importance of microbiomes for plant hosts and ecosystems. Using the common duckweed Lemna minor, we experimentally examined the effects of predation (by bacterivorous protists) and parasitism (by bacteriophages) within microbiomes on plant population size and ecosystem phosphorus removal. Our results revealed that the addition of predators increased plant population size and phosphorus removal, whereas the addition of parasites showed the opposite pattern. The structural equation modelling further pointed out that predation and parasitism affected plant population size and ecosystem function via distinct mechanisms that were both mediated by microbiomes. Our results highlight the importance of understanding microbial trophic interactions for predicting the outcomes and ecosystem impacts of plant-microbiome symbiosis.

Impacts of Fulvic Acid on the Toxicity of the Herbicide Atrazine to Lemna minor.

Fulvic acids (FA) are environmentally prevalent components of dissolved organic carbon. Little research has evaluated their potential influence on the bioavailability of herbicides to non-target aquatic plants. This study evaluated the potential impacts of FA on the bioavailability of atrazine (ATZ) to the aquatic plant Lemna minor. Plants were exposed to 0, 15, 30, 60, 125, and 750 µg/L ATZ in media containing three FA concentrations (0, 5, and 15 mg/L) in a factorial study under static conditions. Fronds were counted after 7- and 14-days exposure and intrinsic growth rates (IGR) and total frond yields were calculated for analysis. Atrazine NOAECs and LOAECs within each FA treatment series (0, 5, or 15 mg/L) were identified and EC50s were estimated. NOAEC/LOAECs for yield and IGR were 60/125 µg/L except for yield in the 0 mg/L-FA series (30/60) and IGR in the 5 mg/L-FA series (30/60). NOAEC/LOAECs were 30/60 µg/L for all treatments and both endpoints after 14 days exposure. EC50s ranged from 88.2 to 106.1 µg/L (frond production 7 DAT), 158.0-186.0 µg/L (IGR, 7 DAT), 74.7-86.3 µg/L (frond production, 14 DAT), and 144.1-151.3 µg/L (IGR, 14 DAT). FA concentrations did not influence the toxicity of ATZ.

Caloric restriction extends lifespan in a clonal plant.

When subjected to dietary caloric restriction (CR), individual animals often outlive well-fed conspecifics. Here, we address whether CR also extends lifespan in plants. Whereas caloric intake in animals comes from ingestion, in plants it derives from photosynthesis. Thus, factors that reduce photosynthesis, such as reduced light intensity, can induce CR. In two lab experiments investigating the aquatic macrophyte Lemna minor, we tracked hundreds of individuals longitudinally, with light intensity-and hence, CR-manipulated using neutral-density filters. In both experiments, CR dramatically increased lifespan through a process of temporal scaling. Moreover, the magnitude of lifespan extension accorded with the assumptions that (a) light intensity positively relates to photosynthesis following Michaelis-Menten kinetics, and (b) photosynthesis negatively relates to lifespan via a power law. Our results emphasize that CR-mediated lifespan extension applies to autotrophs as well as heterotrophs, and suggest that variation in light intensity has quantitatively predictable effects on plant aging trajectories.

Comparison of mercury (Hg) bioaccumulation with mono- and mixed Lemna minor and Spirodela polyrhiza cultures.

Mercury (Hg) is a prevalent and harmful contaminant that persists in the environment. For phytoremediation, it is important to discover which plants can bioaccumulate meaningful amounts of Hg while also tolerating its toxicity. Additionally, increasing biodiversity could create a more resilient and self-sustaining system for remediation. This study explores whether mixed populations of Lemna minor and Spirodela polyrhiza can better bioaccumulate and tolerate Hg than monocultures. Mono- and mixed cultures of L. minor and S. polyrhiza were grown in mesocosms of 0.5 µg/L or 100 µg/L Hg (HgCl2) spiked water for 96 h. Change in weight of duckweed was used to assess Hg tolerance. Diffusive gradients in thin-films (DGTs) were used as surrogate monitoring devices for bioavailable levels of Hg. For biomass growth, the mixed culture of the L. minor was greater than the monoculture at the high dose. The L. minor accumulated more Hg in the mixed culture at the low dose while the S. polyrhiza was higher in the mixed at the high dose. Hg speciation in water was modeled using Windermere Humic Aqueous Model 7 (WHAM7) to compare the bioavailable species indicated by the DGTs.  Potentially due to the controlled conditions, the WHAM7 output of bioavailable Hg was almost 1:1 to that estimated by the DGTs, indicating good predictive capability of geochemical modeling and passive sampler DGT on metal bioavailability. Overall, the mixed cultures statistically performed as well as or better than the monocultures when tolerating and bioaccumulating Hg. However, there needs to be further work to see if the significant differences translate into practical differences worth the extra resources to maintain multiple species.

Evaluation of acute toxicity of an emerging contaminant Oxybenzone on an ecologically important aquatic macrophyte Lemna minor.

Oxybenzone is an ultraviolet filter frequently used in Personal Care Products, plastics, furniture, etc. and is listed as an Emerging Contaminant. This report studied the acute toxicity of Oxybenzone to Lemna minor after exposure to graded concentrations of Oxybenzone for 7 days. IC50 for growth was found to be 8.53 mg L-1. The hormesis effect was reported at lower concentrations, while growth and pigments reduced from 2.5 to 12.5 mg L-1 in a concentration-related manner. The impact of Oxybenzone on protein and antioxidant enzymes- Catalase and Guaiacol Peroxidase revealed less stress up to 2.5 mg L-1 than control, increasing further from 5 to 10 mg L-1. Enzyme activity decreased over-time but always remained higher than control over a period of 7 days. Thus, our findings reveal that indiscriminate discharge of Oxybenzone could be potentially toxic to the aquatic primary producers at higher concentrations, causing an ecological imbalance in aquatic ecosystems.

Ecotoxicological effects of ketoprofen and fluoxetine and their mixture in an aquatic microcosm.

The effects of fluoxetine (antidepressant) and ketoprofen (analgesic) on aquatic ecosystems are largely unknown, particularly as a mixture. This work aimed at determining the effect of sublethal concentrations of both compounds individually (0.050 mg/L) and their mixture (0.025 mg/L each) on aquatic communities at a microcosm scale for a period of 14 d. Several physicochemical parameters were monitored to estimate functional alterations in the ecosystem, while model organisms (Daphnia magna, Lemna sp., Raphidocelis subcapitata) and the sequencing of 16S/18S rRNA genes permitted to determine effects on specific populations and changes in community composition, respectively. Disturbances were more clearly observed after 14 d, and overall, the microcosms containing fluoxetine (alone or in combination with ketoprofen) produced larger alterations on most physicochemical and biological variables, compared to the microcosm containing only ketoprofen, which suffered less severe changes. Differences in nitrogen species suggest alterations in the N-cycle due to the presence of fluoxetine; similarly, all pharmaceutical-containing systems decreased the brood rate of D. magna, while individual compounds inhibited the growth of Lemna sp. No clear trends were observed regarding R. subcapitata, as indirectly determined by chlorophyll quantification. The structure of micro-eukaryotic communities was altered in the fluoxetine-containing systems, whereas the structure of bacterial communities was affected to a greater extent by the mixture. The disruptions to the equilibrium of the microcosm demonstrate the ecological risk these compounds pose to aquatic ecosystems.

miR397 regulates cadmium stress response by coordinating lignin polymerization in the root exodermis in Kandelia obovata.

Secondary lignification of the root exodermis of Kandelia obovata is crucial for its response to adversity such as high salinity and anaerobic environment, and this lignification is also effective in blocking cadmium transport to the roots. However, how the differences in lignification of root exodermis at different developmental stages respond to Cd stress and its regulatory mechanisms have not been revealed. In this study, after analyzing the root structure and cell wall thickness using a Phenom scanning electron microscope as well as measuring cadmium content in the root cell wall, we found that the exodermis of young and mature roots of K. obovata responded to Cd stress through the polymerization of different lignin monomers, forming two different mechanisms: chelation and blocking. Through small RNA sequencing, RLM-5'-RACE and dual luciferase transient expression system, we found that miR397 targets and regulates KoLAC4/17/7 expression. The expression of KoLAC4/17 promoted the accumulation of guaiacyl lignin during lignification and enhanced the binding of cadmium to the cell wall. Meanwhile, KoLAC7 expression promotes the accumulation of syringyl lignin during lignification, which enhances the obstruction of cadmium and improves the tolerance to cadmium. These findings enhance our understanding of the molecular mechanisms underlying the differential lignification of the root exodermis of K. obovata in response to cadmium stress, and provide scientific guidance for the conservation of mangrove forests under heavy metal pollution.

Floral scent of eastern skunk cabbage (Symplocarpus foetidus: Araceae).

Symplocarpus foetidus (L.) Salisb. (eastern skunk cabbage) occurs across a broad geographic range of northeastern North America, blooming in winter between December and March. The inflorescences are well-known for their thermogenic and thermoregulatory metabolic capabilities. The perceptual qualities of their fetid floral aroma have been described widely in the literature, but to date the floral volatile composition remained largely unknown. Here we present a detailed study of the floral scent produced by S. foetidus collected from intact female- and male-stage inflorescences and from dissected floral parts. Our results show a large range of biosynthetically diverse volatiles including nitrogen- and sulfur-containing compounds, monoterpenes, benzenoids, and aliphatic esters and alcohols. We document high inter-individual variation with some organ-specific volatile trends but no clear strong variation based on sexual stage. Multivariate data analysis revealed two distinct chemotypes from our study populations that are not defined by sexual stage or population origin. The chemotype differences may explain the bimodal perceptual descriptions in earlier work which vary between highly unpleasant/fetid and pleasant/apple-like. We discuss the results in ecological contexts including potential for floral mimicry, taking into account existing pollination studies for the species. We also discuss the results in evolutionary contexts, comparing our scent data to published scent data from the close sister species Symplocarpus renifolius. Future work should more closely examine the chemotype occurrence and frequency within these and other populations, and the impact these chemotypes may have on pollinator attraction and reproductive success.

Cultivation of the macrophyte Lemna minor and the microalgae Chlorella sorokiniana in thermal mineral waters: Biomass characteristics, radioisotopes and heavy metals content.

Microalgae and macrophytes are commonly used as human and animal food supplements. We examined the cultivation of the microalgae Chlorella sorokiniana and the duckweed Lemna minor in thermal waters under batch and sequencing batch conditions and we characterized the produced biomass for the presence of essential nutrients as well as for heavy metals and radioisotope content. The highest specific growth rate for the microalgae was observed when 5 or 15 mg/L N were supplemented while the optimal conditions for Lemna minor were observed in the co-presence of 5 mg/L N and 1.7 mg/L P. Lemna minor presented higher concentrations of proteins and lipids comparing to the studied microalgae. Both organisms contained high amounts of lutein (up to 1378 mg/kg for Lemna minor) and chlorophyll (up to 1518 mg/kg for Lemna minor) while ß-carotene and tocopherols were found at lower concentrations, not exceeding a few tens of mg/kg. The heavy metal content varied between the two species. Lemna minor accumulated more Cd, Cu, K, Mn, Na, Ni, and Zn whereas Al, Ca and Mg were higher in Chlorella sorokiniana. Both organisms could be a significant source of essential metals but the occasional exceedance of the statutory levels of toxic metals in food products raises concern for potential risk to either humans or animals. Application of gamma-spectroscopy to quantify the effective dose to humans from 228Ra, 226Ra and 40K showed that Chlorella sorokiniana was well under the radiological limits while the collected mass of Lemna minor was too small for radiological measurements with confidence.

Domestic wastewater treatment by Pistia stratiotes in constructed wetland.

The objective of the study was to evaluate the performance of Pistia stratiotes for treatment of domestic wastewater in a free surface water flow constructed wetland. The objective of the study was to evaluate contaminants removal efficiency of the constructed wetland vegetated with P. stratiotes in treatment of domestic wastewater against Hydraulic retention time (HRT) of 10, 20 and 30 days was investigated. This asks for newer and efficient low-cost nature-based water treatment system which along with cost takes into consideration the sustainability of the ecosystem. Five constructed wetland setups improved the wastewater quality and purify it significantly by reducing the TDS by 83%, TSS by 82%, BOD by 82%, COD by 81%, Chloride by 80%, Sulfate by 77%, NH3 by 84% and Total Oil and Grease by 74%. There was an increase in pH of about 11.9%. Color and odor of wastewater was also improved significantly and effectively. It was observed that 30 days' HRT was optimum for the treatment of domestic wastewater. The final effluent was found to be suitable as per national environmental quality standards and recycled for watering plants and crop irrigation but not for drinking purposes. The treatment in constructed wetland system was found to be economical, as the cost of construction only was involved and operational and maintenance cost very minimal. Even this research was conducted on the sole purpose of commuting the efficiency of pollutant removal in short span time.

Absorption and translocation of selected pharmaceuticals in Pistia stratiotes: Spatial distribution analysis using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Phytoremediation can eliminate pharmaceuticals from aquatic environments through absorption; however, understanding of absorption and transport processes in plants remains limited. In this study, a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry imaging (MALDI-MSI) method was developed to explore the absorption and translocation mechanisms of seven common pharmaceuticals in Pistia stratiotes. Results showed that 2,3-dicyanohydroquinone, an infrequently used matrix, exhibited outstanding performance in MALDI-MSI analysis, producing the highest signal intensity for four of the seven pharmaceuticals. Region of Interest (ROI) analysis revealed that charge speciation of pharmaceuticals significantly influenced their ability to enter vascular bundle. Neutral and positively charged pharmaceuticals easily entered vascular bundle, while negatively charged pharmaceuticals faced difficulty. ROI results for neutral and negatively charged pharmaceuticals exhibited positive correlation with their transfer factor values, indicating that their translocation ability from root to shoot was related to their capacity to enter vascular bundle. However, no correlation was observed for positively charged pharmaceuticals, suggesting that these compounds, upon entering vascular bundle, encountered difficulties in upward translocation through the xylem. This study introduces an innovative approach and offers novel insights into the retention and migration of pharmaceuticals in plant tissues, aiming to enhance the understanding of pharmaceutical accumulation in plants. ENVIRONMENTAL IMPLICATION: Pharmaceuticals in aquatic environment can inflict detrimental effects on both human health and ecosystem. Phytoremediation can remove pharmaceuticals from aquatic environments through absorption. However, our understanding of absorption and transportation of pharmaceuticals in plants remains limited. This study developed a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry imaging (MALDI-MSI) method for pharmaceuticals in plant roots, and to explore the absorption and translocation mechanisms of pharmaceuticals. The study offers direct evidence of differences in accumulation behavior of pharmaceuticals in plants, providing valuable insights for targeted and effective strategies in using plants for remediating the aquatic ecosystem from pharmaceuticals.

Experiments and modeling to develop a Pistia stratiotes based Floating Vegetated System (FVS) for the removal of heavy metals (Pb, Zn, Cr, Cu, Ni).

Floating Vegetated System (FVS) emerged as a green and sustainable technology, presenting a viable solution for treating heavy metals (HMs) contaminated water without disrupting the food web. Pistia stratiotes has been used in the design of FVS due to its abundance of aerenchyma tissues, which contribute to its ability to remain buoyant. FVS exhibited significant HMs removal efficiencies, with Pb top at average 84.4 %, followed by Zn (81.1 %), Cr (78.5 %), Cu (76.5 %) and Ni (73 %). Bio-concentration Factor (BCF) and Translocation Factor (TF) values evaluated the plant's adeptness in metal uptake. For plants treated with Cu, the highest post-treatment chlorophyll content of 9 ± 1 mg.ml-1 was observed while Zn induced plant shows the lowest content of 7.1 ± 0.4 mg.ml-1. Using Box-Behnken Design (BBD), the system achieved 81.48 % Pb removal under optimized conditions such as initial Pb conc. of 9.25 mg. l-1, HRT of 24.49 days and a water depth of 26.52 cm. ANOVA analysis highlighted the significant impact of all the factors such as initial HM conc., HRT and wastewater depth on FVS performance. Kinetic analysis estimated a closer observance to the zero-order model, supported by high determination coefficient (R2) values. In conclusion, the FVS, as one of the most eco-friendly technologies, demonstrates higher potential for treating polluted water bodies, offering a sustainable remedy to global metal pollution challenges. Research on FVS for HMs removal is an area of ongoing interest and there are several potential future studies that could be pursued to further understand and optimize their effectiveness such as optimization of plant species, enhancement of plant-metal interactions, effects of environmental factors, economic feasibility studies, disposal of heavy metals accumulated plant, scale-up and application in real-world settings, etc.

Characterization of the complete chloroplast genome of Wolffia arrhiza and comparative genomic analysis with relative Wolffia species.

Lemnoideae, commonly referred to as the duckweed, are aquatic plants found worldwide. Wolffia species are known for their extreme reduction in size and complexity, lacking both roots and leaves, and they hold the distinction of being the smallest plants among angiosperms. Interestingly, it belongs to the Araceae family, despite its apparent morphological differences from land plants in the same family. Traditional morphological methods have limitations in classifying these plants, making molecular-level information essential. The chloroplast genome of Wolffia arrhiza is revealed that a total length of 169,602 bp and a total GC content of 35.78%. It follows the typical quadripartite structure, which includes a large single copy (LSC, 92,172 bp) region, a small single copy (SSC, 13,686 bp) region, and a pair of inverted repeat (IR, 31,872 bp each) regions. There are 131 genes characterized, comprising 86 Protein-Coding Genes, 37 Transfer RNA (tRNA) genes, and 8 ribosomal RNA (rRNA) genes. Moreover, 48 simple sequence repeats and 32 long repeat sequences were detected. Comparative analysis between W. arrhiza and six other Lemnoideae species identified 12 hotspots of high nucleotide diversity. In addition, a phylogenetic analysis was performed using 14 species belonging to the Araceae family and one external species as an outgroup. This analysis unveiled W. arrhiza and Wolffia globosa as closely related sister species. Therefore, this research has revealed the complete chloroplast genome data of W. arrhiza, offering a more detailed understanding of its evolutionary position and phylogenetic categorization within the Lemnoideae subfamily.