Uptake of perfluoroalkyl substances PFOS and PFOA by free-floating hydrophytes Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms.

The phytoremediation potential of floating aquatic plants to accumulate and remove two common PFAS from contaminated water was investigated. Free-floating hydrophytes Eichhornia crassipes and Pistia stratiotes were grown in water spiked with 0.5, 1, or 2 ppm perfluorooctanoic acid (PFOA) or perfluorooctanesulfonic acid (PFOS) for seven days. Both species were able to accumulate PFOA and PFOS in this time frame, with translocation factors (TF) ranging from 0.13 to 0.57 for P. stratiotes and 0.18 to 0.45 for E. stratiotes, respectively. E. crassipes accumulated a greater amount of PFOA and PFOS than P. stratiotes, with 178.9 ug PFOA and 308.5 ug PFOS removed by E. crassipes and 98.9 ug PFOA and 137.8 ug PFOS removed by P. stratiotes at the highest concentrations. Root tissue contained a higher concentration of PFOA and PFOS than shoot tissue in both species, and the concentration of PFOS was generally significantly higher than PFOA in both E. crassipes and P. stratiotes, with concentrations of 15.39 and 27.32 ppb PFOA and 17.41 and 80.62 ppb PFOS in shoots and roots of P. stratiotes and 12.59 and 37.37 ppb PFOA and 39.92 and 83.40 ppb PFOS in shoots and roots of E. crassipes, respectively. Both species may be candidates for further phytoremediation studies in aquatic ecosystems.

This study investigates the feasibility of using wetland plants for the phytoremediation of PFAS. Prior published studies examine various plant interactions with PFAS but do not evaluate remediation potential of P. stratiotes.

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.

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.

Copper and zinc accumulation, distribution, and tolerance in Pistia stratiotes L.; revealing the role of root caps.

Pollution by potentially toxic trace metals, such as copper or zinc, is global. Both Cu and Zn are essential microelements, which in higher concentrations become toxic. The aquatic plant Pistia stratiotes(L. has great potential for phytoremediation. Also, it has an unusually large and easily detachable root cap, which makes it a suitable model for studying the potential role of the root cap in metal uptake. Plant response to environmentally relevant concentrations of Cu (0.1, 0.3, and 1 µM) and Zn (0.3, 1, and 3 µM) was investigated with the aim of studying their interaction and distribution at the root tissue level as well as revealing their tolerance mechanisms. Changes in the root anatomy and plant ionome were determined using light and fluorescence microscopy, ICP-MS, and µXRF imaging. Alterations in photosynthetic activity caused by Cu or Zn excesses were monitored by direct imaging of fast chlorophyll fluorescence kinetics (OJIP). Fe and Mn were preferentially localized in the root cap, while Ca, Cu, Ni, and Zn were mainly in the root tip regardless of the Cu/Zn treatment. Translocation of Cu and Zn to the leaves increased with higher doses, however the translocation factor was the lowest in the highest treatments. Measurements of photosynthetic parameters showed a higher susceptibility of electron transport flux from QA to QB under increasing Cu than Zn supply. This, along with our findings regarding the root anatomy and the differences in Ca accumulation and distribution, led to the conclusion that P. stratiotes is more effective for Zn remediation than Cu.

Gene co-expression networks unravel the molecular responses of freshwater hydrophytes to combined stress of salinity and cadmium.

Salinization in freshwater lakes is becoming a serious global environmental problem, especially in lakes of plateaus such as south-western plateau of China. However, limited information is available about the molecular response of freshwater hydrophytes to salinity under multiple stress. In the present study, a weighted gene co-expression network (WGCNA) was used to identify the modules of co-expressed genes in the physiological and biochemical indicators of Pistia stratiotes to determine its molecular response to salinity (NaCl) alone and when combined with cadmium (Cd). The physiological and biochemical indicators showed that P. stratiotes improved its salt tolerance by enhancing photosynthetic abilities, reducing oxidative stress, and inducing osmoprotectant generation. Morever, addition of NaCl reduced the Cd accumulation in P. stratiotes. Transcriptome and WGCNA analysis revealed that the pathways of alpha-linolenic acid metabolism, ribosomal, flavonoid biosynthesis, and phenylpropanoid biosynthesis were significantly enriched in both treatments. Genes associated with photosynthesis-antenna proteins, nitrogen metabolism, and the acid cycle pathways were only expressed under salinity stress alone, while the proteasome pathway was only significantly enriched in the combined salinity and Cd treatment. Our findings provide novel insights into the effects of salinization on aquatic plants in freshwater ecosystems and the management of aquatic ecosystems under global change.

Integrative Evaluation of the Ecological Hazards by Microplastics and Heavy Metals in Wetland Ecosystem.

This study was performed to evaluate the impact of microplastics and heavy metals (Pb, Cd, Cr, Cu, Zn, Ni) on sediments, water, aquatic plants (Pistia stratiotes, Alternanthera philoxeroides, and Ipomoea carnea), and fish (Labeo rohita) samples collected from five different sites in the Bajwat wetlands in Sialkot, Pakistan. The concentrations of Pb, Cd, and Cr were above the permissible limits devised by WHO in all the ecosystem components (i.e. sediments, water, plants, and fish) at all sites. The maximum amount of microplastic particles (2317 microplastic particles per kg of sediments) was recorded at Site 1. The filaments were the most commonly found type of microplastics. Plants and fish samples also showed considerable concentration of metals. The multivariate statistical analysis revealed anthropogenic sources of elevated concentrations of metal elements which could cause adverse biological effects in the ecosystem.

Integrated transcriptomics and metabolomics reveal key metabolic pathway responses in Pistia stratiotes under Cd stress.

Cadmium (Cd) can interfere with plant gene expression, change the content of metabolites and affect plant growth. In this study, untargeted metabolomics (LC-MS) and RNA-Seq sequencing were performed on root tissues of Pistia stratiotes exposed to Cd stress. The results showed that cadmium stress affected the accumulation and transport of cadmium in plants and increased the content of soluble sugar, the activities of ascorbate peroxidase (APX), and peroxidase (POD) by 34.89%, 41.45%, and 6.71% on average, and decreased the activity of superoxide dismutase (SOD) by 51.51% on average. At the same time, the contents of carotenoid, chlorophyll a, and chlorophyll b decreased by 29.52%, 20.11%, and 13.14%, respectively, Thus affecting the growth and development of plants. Metabolomic analysis showed that Cd stress affected eight metabolic pathways, involving 27 differentially expressed metabolites, mainly including unsaturated fatty acids, amino acids (phenylalanine), nucleotides, sulfur compounds, and flavonoids. By transcriptome analysis, a total of 3107 differentially expressed genes (DEGs, 2666 up-regulated genes, and 441 down-regulated genes) were identified, which were mainly involved in four pathways, among which glutathione metabolism and lignin biosynthesis were the key metabolic pathways. In conclusion, this study reveals the metabolic and transcriptional response mechanisms of P. stratiotes to Cd stress through multi-omics, providing the theoretical basis for the phytoremediation of water contaminated by Cd.

Pistia stratiotes has renoprotective potentials in ischemia reperfusion injury in normal and diabetic rats.

OBJECTIVE: Even though oxidative and inflammatory bursts are a big part of renal reperfusion injury (RI/R), Pistia stratiotes (PS) has been used for a long time to stop these overreactions. People have said that it can drop both blood sugar and cholesterol. Hence, the goal of this study was to show how PS changed kidney reperfusion damage in both diabetic and normal rats. MATERIALS AND METHODS: In the study, 30 min of renal ischemia (RI) was followed by 1 h of recovery for each rat. Before the test, PS (100 mg/kg p. o.) was given to the animals for 7 days. Then, using the mixture from the separated kidney tissues, the antioxidant, inflammation, and histopathological effects were determined. RESULTS: When compared to RI/R, diabetic rats given PS had lower blood sugar, aspartate aminotransferase, blood urea nitrogen, and creatinine, myeloperoxidase, C-reactive protein, and tumor necrosis factor-alpha levels in their urine. CONCLUSION: PS potentially worked in hyperglycemic rats protecting them against RI/R. It is possible that PS's ability to protect the kidneys of the test rats is due to its ability to fight free radicals, lower blood sugar, and stop inflammation.

Phytotoxicity and accumulation of BPS to Pistia stratiotes under the influence of microplastics.

Bisphenol S (BPS) is a contaminant of emerging concern, its exposure and phytotoxicity towards plants, however, is scarce. This study aimed at revealing the BPS translocation in plants and phytotoxicity in the presence of Polystyrene (PS) microplastics. Results found that BPS and PS showed no effect on plant growth, indicating the tolerance of plants towards BPS and PS co-contamination. In addition, plants enriched BPS from soil, and a major part of absorbed BPS was accumulated in roots, as supported by the higher BCF value in roots compared with leaves. Besides, the low TF (<1) suggested the capacity of plants to accumulate BPS in roots, and less translocation to leaves. PS negatively affected the translocation of BPS in plants. PS with large size (5 µm) also increased the distribution of BPS in organelles. Exposure risk assessment suggested low concern of BPS carried in plants to human health. This study underlines the bioaccumulation of BPS in plants, and the effects of PS in the translocation process.

The chromosome-level genome of a free-floating aquatic weed Pistia stratiotes provides insights into its rapid invasion.

Pistia stratiotes (Araceae), commonly referred to as water lettuce, is one of the most notorious weeds that cause severe damage to the economy and natural ecosystems of infested areas. In order to explore the mechanism of its rapid invasion, here, we assembled a high-quality chromosome-level genome for P. stratiotes based on the Illumina sequencing, PacBio sequencing, and Hi-C scaffolding technology. The assembled genome is 311.87 Mb in size with a contig N50 of 1.08 Mb. The contigs were further anchored on 14 pseudochromosomes with a scaffold N50 of 21.21 Mb. A total of 20,356 protein-coding genes were predicted, of which 79.35% were functionally annotated here. Evolutionary analysis showed that P. stratiotes and Colocasia esculenta were clustered together as sister lineages that diverged approximately 61 Ma. The synteny analyses indicated that two whole-genome duplication (WGD) events occurred within a short period in P. stratiotes. Moreover, comparative genome analysis indicated that the expansion of gene families corresponding to disease resistance might contribute to rapid invasion in P. stratiotes. Also, we analysed the disease-resistance gene family (NBS-LRR) involved in plant defence. A genome-wide search in P. stratiotes genome identified 85 NBS-LRR genes in this study. In conclusion, this study provides some new insights into the evolution of the invasive aquatic plant P. stratiotes. Our reference genome will also provide valuable resources for future invasion genomic research programmes.

The Ribosomal DNA Loci of the Ancient Monocot Pistia stratiotes L. (Araceae) Contain Different Variants of the 35S and 5S Ribosomal RNA Gene Units.

The freshwater plant water lettuce (Pistia stratiotes L.) grows in warm climatic zones and is used for phytoremediation and biomass production. P. stratiotes belongs to the Araceae, an ecologically and structurally diverse early monocot family, but the phylogenetic relationships among Araceae members are poorly understood. Ribosomal DNAs (rDNAs), including the 35S and 5S rDNA, encode the RNA components of ribosomes and are widely used in phylogenetic and evolutionary studies of various plant taxa. Here, we comprehensively characterized the chromosomal locations and molecular organization of 35S and 5S rDNA genes in water lettuce using karyological and molecular methods. Fluorescence in situ hybridization revealed a single location for the 35S and 5S rDNA loci, each on a different pair of the species' 28 chromosomes. Molecular cloning and nucleotide sequencing of 35S rDNA of P. stratiotes, the first representative Araceae sensu stricto in which such a study was performed, displayed typical structural characteristics. The full-length repeat showed high sequence conservation of the regions producing the 18S, 5.8S, and 25S rRNAs and divergence of the internal transcribed spacers ITS1 and ITS2 as well as the large intergenic spacer (IGS). Alignments of the deduced sequence of 18S rDNA with the sequences available for other Araceae and representatives of other clades were used for phylogenetic analysis. Examination of 11 IGS sequences revealed significant intra-genomic length variability due to variation in subrepeat number, with four types of units detected within the 35S rDNA locus of the P. stratiotes genome (estimated size 407 Mb/1C). Similarly, the 5S rDNA locus harbors gene units comprising a conserved 119-bp sequence encoding 5S rRNA and two types of non-transcribed spacer (NTS) sequences. Type I was classified into four subtypes, which apparently originated via progressive loss of subrepeats within the duplicated NTS region containing the 3' part of the 5S rRNA gene. The minor Type II NTS is shorter than Type I and differs in nucleotide composition. Some DNA clones containing two or three consecutive 5S rDNA repeats harbored 5S rDNA genes with different types of NTSs, confirming the mosaic composition of the 5S rDNA locus.

Physiological defense and metabolic strategy of Pistia stratiotes in response to zinc-cadmium co-pollution.

Pistia stratiotes is a cadmium (Cd) hyperaccumulating plant with strong bioaccumulation and translocation capacity for Cd. A hydroponic experiment was used to evaluate the combined effect of Zinc (Zn) and Cd at different concentrations on leaf growth and metabolism of P. stratiotes. This study revealed the physiological defense and metabolic strategy of responses to Zn-Cd co-pollution. With the Zn50Cd1, Zn50Cd10, Zn100Cd1, and Zn100Cd10 treatments for 9 d, the relative crown diameter, relative leave number, and ramet number of the plant had no significant difference with the control. Under the compound treatments containing Zn50Cd50 and Zn100Cd50, the activity of the glyoxalase system and amino acid metabolism in the leaves were inhibited. The leaf photosynthetic apparatus increased heat dissipation to reduce the damage to the photosystem II (PS II) reaction center caused by excess excitation energy under Zn-Cd stress. This safeguarded the balance between the absorption and utilization of light energy. Compared to the control, the Zn and Cd co-pollution for 9 d had no effect on the reduced glutathione (GSH) and oxidized glutathione (GSSG) contents. There was no effect on the dehydroascorbate reductase (DHAR) and glutathione reductase (GR) activities, but there was increased ascorbate peroxidase (APX) activity and oxidized ascorbic acid (DHA) content. These increased the antioxidant capacity of the ascorbate-glutathione (AsA-GSH) cycle. The treated plants also had increased levels of carnosol and substances related to lipid metabolism including 9, 10-Dihydroxystearate, Prostaglandin G2, Sphingosine, and 13-L-Hydroperoxylinoleic acid, maintaining the cell stability and resistance to the Zn-Cd stress.

Evaluation of electro-assisted phytoremediation (EAPR) system for heavy metal removal from synthetic leachate using Pistia stratiotes.

The highest waste generated in Malaysia is composed of municipal solid waste, which is mainly managed by landfilling. Heavy metals in leachate generated from landfill could have caused hazardous effects to human and environment. EAPR has been increasingly applied to treat soil and wastewater. This technique serves as a potential tool for remediation of real leachate. Metals (Mn, Cd, Fe, Ni, Pb, Zn) uptake by Pistia stratiotes were evaluated via flame atomic adsorption spectrophotometer. Pb and Fe could be the elements that were more efficiently removed by P. stratiotes in the EAPR system. The removal efficiency was 59.86 ± 9.98 and 56.56 ± 18.08% for Pb and Fe, respectively. EAPR significantly reduced the BOD (9.37 ± 2.36 mg/L), color (120.00 ± 5.77 PtCo), and turbidity (25.50 ± 11.96 NTU) of synthetic leachate. An obvious accumulation of heavy metals was observed at roots based on BCF and TF values. BCF values of Pb (18,999.06 ± 8,321.76) and Fe (16,090.81 ± 5,844.36) in the EAPR system were more than 103, which indicates that P. stratiotes is a hyperaccumulator. Further study on the upregulated genes is needed to comprehend the molecular basis of heavy metal stress tolerance.

EAPR greatly reduced heavy metals, BOD, color, and turbidity of synthetic leachate. The use of water lettuce in EAPR could be another plant alternative for potential remediation of real leachate which is extremely difficult to be treated.

Tolerance mechanism and phytoremediation potential of Pistia stratiotes to zinc and cadmium co-contamination.

Pistia stratiotes can not only effectively remediate eutrophic water, but also displays strong absorption and bioaccumulation abilities for heavy metals. However, it has not been well-understood how the plant resists the combined stress of heavy metals. In these experiments, the morphophysiological traits, the ascorbate-glutathione (AsA-GSH) cycle, the glyoxalase system, and the contents of zinc (Zn) and cadmium (Cd) were investigated under Zn and Cd co-pollution. The AsA-GSH cycle and glyoxalase system could coordinately alleviate the oxidative and carbonyl stress, which was identified as an important tolerance mechanism. With Zn50Cd1, Zn50Cd10, Zn100Cd1, and Zn100Cd10 treatments for 18 days, 90.75-93.69% of Zn and 88.13-96.96% Cd accumulated in the roots. Treatments with Zn50Cd50, and Zn100Cd50 for 18 days resulted in a decrease of stress tolerance and chlorophyll content in leaves, an increase in plasma membrane permeability, a massive accumulation of methylglyoxal (MG), and visible toxic symptoms. Additionally, the bioaccumulation factor (BCF) for roots and shoots and the translocation factor (TF) were >1, and the content of Cd in shoots was no <100 mg·kg-1. This indicated P. stratiotes was a Cd hyperaccumulator and have great potential for the phytoremediation of heavy metal contaminated water.Novelty statement Pistia stratiotes, a cadmium hyperaccumulator, has great application potential for the phytoremediation of zinc and cadmium co-polluted water.

Hydrophobic and dispersible Cu(I) desulfurization adsorbent prepared from Pistia stratiotes for efficient desulfurization.

Improving the adsorption capacity of adsorbents is a good way to boost their desulfurization efficiency. Optimizing the dispersion of metal nanoparticles and enhancing the stability of the metal valence state are essential to maximizing the adsorption capacity of the metal-loaded desulfurization adsorbent. Pistia stratiotes can absorb the Cu in water and evenly disperse it throughout the plant, allowing the production of a highly dispersed Cu(I) adsorbent (PSAC-Cu(I)). During the usage and storage of PSAC-Cu(I), Cu(I) oxidizes to Cu(II) when it comes in contact with oxygen and water, reducing its adsorptive capacity; hence, we modified PSAC-Cu(I) hydrophobically using polydimethylsiloxane (PDMS) to generate PSAC-Cu(I)-P(200). The outcome of the two-month exposure experiments showed that only 4.7% of the Cu(I) of PSAC-Cu(I)-P(200) was oxidized in the humid atmosphere, whereas PSAC-Cu(I) was almost fully oxidized. Moreover, the dibenzothiophene adsorption capacity of PSAC-Cu(I)-P(200) in a model oil with a water concentration of 250 ppmw is 68 mg g-1, which is 1.62 times that of PSAC-Cu(I). When 10 wt% toluene was added to the model oil, the adsorption desulfurization capacity of PSAC-Cu(I)-P(200) decreased to 86.8% of the original. This shows that PSAC-Cu(I)-P(200) has good stability and excellent adsorptive desulfurization performance.

Optimization of the phytoremediation conditions of wastewater in post-treatment by Eichhornia crassipes and Pistia stratiotes: kinetic model for pollutants removal.

This study aims at determining the optimal conditions for pollutants removal in wastewater using Eichhornia crassipes (E. crassipes) and Pistia stratiotes (P. stratiotes) as appropriate aquatic plants for a post-treatment by phytoremediation. From factors such as residence time, plant density and initial PO43- concentration, four responses, i.e. the removal efficiency of PO43-, NO3-, NH4+ and the chemical oxygen demand (COD) were followed, using complete factorial design. After validation of the regression models by the statistical analyses, optimal conditions were obtained by using the global desirability function. Global desirabilities of 0.96 and 0.97 were respectively obtained for E. crassipes and P. stratiotes, for a residence time of 30 days, a plant density of 60 feet/m2 and an initial PO43- concentration of 10 mg/L. Using E. crassipes, this corresponds to the elimination of 94.2% of PO43-; 93.3% of NO3-; 95.0% of NH4+ and 63.6% of COD. In the case of P. stratiotes, 93.9% of PO43-; 83.4% of NO3-, 99.5% of NH4+ and 84.4% of COD were removed. Finally, under the used conditions, E. crassipes are able to better eliminate phosphorus and nitrates, while P. stratiotes are very effective in removing NH4+ and COD.

Preparation of CdS@C Photocatalyst Using Phytoaccumulation Cd Recycled From Contaminated Wastewater.

Cadmium is one of the most toxic heavy metal contaminants in soils and water bodies and poses a serious threat to ecosystems and humans. However, cadmium is also an important resource widely used in many industries. The recovery of cadmium in the form of high-value products is considered as an ideal disposal strategy for Cd-contaminated environments. In this work, Pistia stratiotes was used to recycle cadmium from wastewaters through phytoaccumulation and then transformed into carbon-supported cadmium sulfide photocatalyst (CdS@C) through carbonization and hydrothermal reaction. The CdS@C photocatalyst contained a mixture of cubic and hexagonal CdS with lower band gap energy (2.14 eV) and high electron-hole separation efficiency, suggesting an excellent photoresponse ability and photocatalytic efficiency. The impressive stability and photocatalytic performance of CdS@C were demonstrated in efficient photodegradation of organic pollutants. •OH and O2•- were confirmed as the major active species for organic pollutants degradation during CdS@C photocatalysis. This work provides new insights into addressing Cd contaminated water bodies and upcycling in the form of photocatalyst.

Phytoremediation of synthetic textile dyes: biosorption and enzymatic degradation involved in efficient dye decolorization by Eichhornia crassipes (Mart.) Solms and Pistia stratiotes L.

The effectiveness of four aquatic floating plants: Eichhornia crassipes, Pistia stratiotes, Lemna minor, Salvinia sp., and a submerged plant Hydrilla sp. on decolorization and detoxification of five structurally different textile dyes: CI Direct Blue 201 (DB 201), Cibacron Blue FR, Cibanone Gold Yellow RK, Vat Green FFB, and Moxilon Blue GRL were studied. The E. crassipes and P. stratiotes showed complete decolorization of all the dyes tested, while Salvinia sp. (79-86%), L. minor (16-24%), and Hydrilla sp. (6-13%) were recorded as the least tolerance for all the dyes even after 14 days of incubation. Therefore, E. crassipes and P. stratiotes were selected for further studies using DB 201 as the model dye. E. crassipes and P. stratiotes showed complete decolorization of DB 201 at 48 and 84 h of incubation, respectively, and decolorization was well effective in the pH range 6-9. The crude extract of intracellular enzymes obtained from the roots of E. crassipes (46%) and P. stratiotes (20%) showed significant involvement on decolorization of DB 201, compared with the activity of crude extracellular extract and isolated endophytic bacteria and fungi (p ≤ 0.05). Further, 18 and 22% of biosorption of DB 201 dye were recorded by E. crassipes and P. stratiotes, respectively, suggesting that decolorization mechanisms of DB 201 dye by E. crassipes and P. stratiotes were based on biosorption and intracellular enzyme activities. The FTIR spectra and seed germination assay confirmed biodegradation and detoxification of DB 201 dye by E. crassipes and P. stratiotes plants along with complete color removal. Thus, present study confers the potential applicability of E. crassipes and P. stratiotes plants for textile dye removal and release to the environment without further treatment.

Effects of fragmentation of clones compound over vegetative generations in the floating plant Pistia stratiotes.

BACKGROUND AND AIMS: Clonal plants dominate many plant communities, especially in aquatic systems, and clonality appears to promote invasiveness and to affect how diversity changes in response to disturbance and resource availability. Understanding how the special physiological and morphological properties of clonal growth lead to these ecological effects depends upon studying the long-term consequences of clonal growth properties across vegetative generations, but this has rarely been done. This study aimed to show how a key clonal property, physiological integration between connected ramets within clones, affects the response of clones to disturbance and resources in an aquatic, invasive, dominant species across multiple generations. METHODS: Single, parental ramets of the floating stoloniferous plant Pistia stratiotes were grown for 3 weeks, during which they produced two or three generations of offspring; connections between new ramets were cut or left intact. Individual offspring were then used as parents in a second 3-week iteration that crossed fragmentation with previous fragmentation in the first iteration. A third iteration yielded eight treatment combinations, zero to three rounds of fragmentation at different times in the past. The experiment was run once at a high and once at a low level of nutrients. RESULTS: In each iteration, fragmentation increased biomass of the parental ramet, decreased biomass of the offspring and increased number of offspring. These effects persisted and compounded from one iteration to another, though more recent fragmentation had stronger effects, and were stronger at the low than at the high nutrient level. Fragmentation did not affect net accumulation of mass by groups after one iteration but increased it after two iterations at low nutrients, and after three iterations at both nutrient levels. CONCLUSIONS: Both the positive and negative effects of fragmentation on clonal performance can compound and persist over time and can be stronger when resource levels are lower. Even when fragmentation has no short-term net effect on clonal performance, it can have a longer-term effect. In some cases, fragmentation may increase total accumulation of mass by a clone. The results provide the first demonstration of how physiological integration in clonal plants can affect fitness across generations and suggest that increased disturbance may promote invasion of introduced clonal species via effects on integration, perhaps especially at lower nutrient levels.

Characterization of the complete chloroplast genome sequence of Pistia stratiotes (Araceae) and its phylogenetic implications.

Pistia stratiotes is an invasive aquatic weed in South China. In this study, the first complete chloroplast (cp) genome of P. stratiotes was reported and phylogenetic analysis was conducted with Araceae species based on the cp genome sequences. The genome is a circular molecule of 164,551 bp in length with 36.00% average GC content and includes a large single-copy region (90,705 bp), a small single-copy region (21,886 bp), and two inverted repeat regions (25,980 bp). It contains a total of 129 genes, including 84 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. The maximum likelihood tree indicated that P. stratiotes is related to the genus of Alocasia. The cp genome will provide useful molecular data for further phylogenetic and evolutionary analysis of P. stratiotes.