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Which is very rich in protein in plant Lemna minor L. abundant in Turkey ecologically plays a very important role in protecting the elimination of water pollution and aquaculture environment balance. In this study, in vitro propagation of this plant with Temporary Immersion System Bioreactor and determination of the effects of used plant growth regulators on the protein content of the plant were aimed. With this objective different variant of media with and without sucrose, varying pH and concentrations of BAP, kinetin, TDZ in medium were analyzed. Experiments for micropropagation were performed for 8 hours in the dark and 16 hours in white fluorescent light (150 μ mol photons m-2s-1) under photoperiod and at 24 ± 1 ° C. The highest plant growth was observed at pH 7.23 in sugar free liquid MS medium containing 0.2 mg/L BAP. 50.44 plants per explant were recorded in this medium. In addition, the maximum number of plants per explant in liquid MS medium containing 0.05 mg/L kinetin was calculated as 57,823 and the maximum number of plants per explant in liquid MS medium containing 0.6 mg/L TDZ was calculated as 50.74. As a result of nitrogen determination studies with Kjeldahl method, the protein value of the plant was determined as 25.5%. As a result of hormone application, it was seen that protein content in plant increased to 29.18% with 0.5 mg/L BAP. It was concluded that the aim of the study were fulfilled and positive effects of Temporary Immersion System Bioreactors on plant multiplication were found. [ABSTRACT FROM AUTHOR]

The influence of water brownification (an increase in water color) on floating-leaved macrophytes appears to be an important issue in predicting the consequences of climate change in freshwater ecosystems. To fill the gap in the knowledge in this area, we performed a laboratory experiment aiming to test the impact of humic acid (HA) on Lemna minor sampled from an oxbow lake. Plants were exposed over seven days to four different additions of pure HA (resulting in DOC concentrations between 5.0 ± 0.1 mg dm−3 and 36.5 ± 0.4 mg dm−3). Changes in duckweed total fresh biomass, leaf area and the root length were measured, as well as the concentrations of total phosphorus, phosphates and nitrates in the water. The study did not find any significant decrease in either the biomass or leaf area of L. minor under conditions of enhanced HA content. However, we found that a moderate increase in HA in water promoted the growth of duckweed roots, thus, increasing the biomass but not the leaf area. In contrast, a large increase in HA in the water suppressed the growth of roots in L. minor, which was also in coincidence with less nutrient depletion in the water.

Usually, chromosome sets (karyotypes) and genome sizes are rather stable for distinct species and therefore of diagnostic value for taxonomy. In combination with (cyto)genomics, both features provide essential cues for genome evolution and phylogenetic relationship studies within and between taxa above the species level. We present for the first time a survey on chromosome counts and genome size measurement for one or more accessions from all 36 duckweed species and discuss the evolutionary impact and peculiarities of both parameters in duckweeds.

In accordance with the opinion of the World Health Organization and the World Water Council the development of effective technologies for the treatment of wastewater from heavy metals for their discharge into water bodies or reuse is an urgent task nowadays. Phytoremediation biotechnologies is the most environmentally friendly and cheapest way of the treatment of wastewater, suitable for sustainable development principals. The main disadvantage of the phytoremediation is the slow speed of the process. A method for accelerating the process of phytoremediation by the combined effect of magnetic and weak electric fields is proposed. The purpose of this study is to determine the values of the parameters of the magnetic and weak electric fields that are most suitable for extracting cuprum ions from wastewater using the higher aqua plants (Lemna minor). A corresponding technological process based on the results of the study is proposed. The results have shown that the removal of copper cations from sulfate solutions effectively occurs in the initial period of time (1–5 hours) under the influence of a magnetic field with an intensity of H = 2 kA/m. Under the combined influence of an electrical current with density j = 240 μA/cm2 and a magnetic field (H = 2 kA/m) the highest rate of copper extraction by duckweed leaves is achieved. Under these conditions, the greatest growth and development of plant leaves occurs. The paper presents the results of determining of the parameters of the electrochemical release from the eluate of the spent phytomass of duckweed. It has been determined that the release of metal occurs at E = 0.32 V. An original scheme for wastewater treatment from copper with subsequent separation of copper from the spent phytomass of duckweed is proposed. In general, the presented results are a scientific justification of wastewater treatment technologies and a contribution to resolving the crisis in the field of fresh water supply. An important contribution in the circular economy is a technology recommendation proposed for recovering copper from duckweed after wastewater treatment. [ABSTRACT FROM AUTHOR]

The duckweed family (Lemnaceae) is a group of free‐floating aquatic plants with bodies consisting of single floating fronds that multiply clonally. Although they are known to have the fastest relative growth rate (RGR) among higher plants, their functional trait coordination in relation to within‐family variation of RGR is poorly understood.We tested how duckweed species fit within the trait covariation patterns known as the world‐wide leaf economics spectrum (LES). To this end, several functional traits were evaluated for 15 duckweed species, and their covariation patterns were compared with those in the global database of plant functional traits.As a group, duckweeds exhibited the most acquisitive suite of traits, with extremely small leaf mass per area (LMA), short life span and high mass‐based photosynthetic rate (Amass). These LES traits showed a tight correlation with RGR, corroborating our hypothesis that acquisitive leaf resource economics underpins their extremely high RGR. However, unlike other higher plants, LMA showed weak association with leaf life span and Amass within duckweed family. We also found a unique positive correlation between duckweed LMA and area‐based photosynthetic rates, an indication that their LMA represents different functional significance compared to typical higher plants.Synthesis. Duckweeds, the world's fastest growing plants, mostly follow the world‐wide LES and locate at its extreme end. The slight deviation from the LES highlights that duckweeds experience some physical and chemical constraints not faced by other higher plants. [ABSTRACT FROM AUTHOR]

We investigated the relative sensitivity of duckweed Lemna minor and six species of algae to seven herbicides, using an efficient high-throughput microplate-based toxicity assay. First, we assessed the sensitivity of L. minor to the seven herbicides, and then we compared its sensitivity to that of previously published data for six algal species based on EC50 values. For five herbicides, the most sensitive species differed: L. minor was most sensitive to cyclosulfamuron: Raphidocelis subcapitata was most sensitive to pretilachlor and esprocarb: Desmodesmus subspicatus was most sensitive to pyraclonil; and Navicula pelliculosa was most sensitive to pyrazoxyfen. Simetryn was evenly toxic to all species, whereas 2,4-D was evenly less toxic, with only small differences in species sensitivity. These results suggested that a single algal species cannot represent the sensitivity of the primary producer assemblage to a given herbicide. Therefore, to assess the ecological effects of herbicides, aquatic plant and multispecies algal toxicity data sets are essential. [ABSTRACT FROM AUTHOR]

Duckweeds are a group of monocotyledonous aquatic plants in the Araceae superfamily, represented by 37 species divided into five genera. Duckweeds are the fastest growing flowering plants and are distributed around the globe; moreover, these plants have multiple applications, including biomass production, wastewater remediation, and making pharmaceutical proteins. Dotted duckweed (Landoltia punctata), the sole species in genus Landoltia, is one of the most resilient duckweed species. The ribosomal DNA (rDNA) encodes the RNA components of ribosomes and represents a significant part of plant genomes but has not been comprehensively studied in duckweeds. Here, we characterized the 5S rDNA genes in L. punctata by cloning and sequencing 25 PCR fragments containing the 5S rDNA repeats. No length variation was detected in the 5S rDNA gene sequence, whereas the nontranscribed spacer (NTS) varied from 151 to 524 bp. The NTS variants were grouped into two major classes, which differed both in nucleotide sequence and the type and arrangement of the spacer subrepeats. The dominant class I NTS, with a characteristic 12-bp TC-rich sequence present in 3–18 copies, was classified into four subclasses, whereas the minor class II NTS, with shorter, 9-bp nucleotide repeats, was represented by two identical sequences. In addition to these diverse subrepeats, class I and class II NTSs differed in their representation of cis-elements and the patterns of predicted G-quadruplex structures, which may influence the transcription of the 5S rDNA. Similar to related duckweed species in the genus Spirodela, L. punctata has a relatively low rDNA copy number, but in contrast to Spirodela and the majority of other plants, the arrangement of the 5S rDNA units demonstrated an unusual, heterogeneous pattern in L. punctata , as revealed by analyzing clones containing double 5S rDNA neighboring units. Our findings may further stimulate the research on the evolution of the plant rDNA and discussion of the molecular forces driving homogenization of rDNA repeats in concerted evolution. [ABSTRACT FROM AUTHOR]

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 β-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. [Display omitted] • Chlorella sorokiniana and Lemna minor cultivation in thermal waters. • Higher concentration of proteins, lipids, lutein and chlorophyll in Lemna biomass. • Both organisms are substantial source of Ca, Cu, Fe and Zn for humans and animals. • Pb in Lemna minor was above the maximum level set by EU for food supplements. • Chlorella sorokiniana was found to be well under the radiological limits. [ABSTRACT FROM AUTHOR]

• Boron negatively affected growth of aquatic plants Salvinia natans and Lemna minor. • Boron reduced photosynthetic capacity in the plants at low concentrations. • The presence of EDTA had a limited influence on the toxicity of boron. • Our findings shed light on the effects of boron toxicity on aqueous organisms. Even though boron is a widely used element in various industries and a contributor to water pollution worldwide, few studies have examined the toxicity of boron in aquatic plants. EDTA is used to maintain aquatic plants cultures, however it is possible to modify the toxicity of metals. The objective of this study is to assess the toxicity of boron in aquatic plants and explore the impact of EDTA presence on the resulting toxic responses. Floating watermoss Salvinia natans and duckweed Lemna minor were exposed to concentrations ranging from 5 to 100 mg/L for 7 days and 1 to 60 mg/L for 3 days, respectively. Growth and photosynthetic activity parameters were investigated in the presence and absence of EDTA. Growth inhibitions in both aquatic plants were observed in a concentration-dependent manner, irrespective of the presence or absence of EDTA. For instance, based on the specific growth rate (leaves coverage), EC 10 values for S. natans were calculated as 12.7 (9.9–15.3) mg/L and 8.0 (5.8–10.3) mg/L with and without EDTA, respectively. In the case of L. minor , EC 10 values were calculated as 1.3 (0.8–1.89) mg/L and 2.0 (0.4–4.3) mg/L with EDTA without EDTA, respectively. Significant effects were also observed on the photosynthetic capacity, however there was no change in the increase of boron concentration. Generally, negligible effects of EDTA to the toxicity of boron were observed in the present study. By comparing toxicity results based on the presence and absence of EDTA, which is an essential element in the test medium, the results of this study are expected to be utilized for the ecological risk assessment of boron in aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Heavy metals (HMs) contamination of water bodies severely threatens human and ecosystem health. There is growing interest in the use of duckweeds for HMs biomonitoring and phytoremediation due to their fast growth, low cultivation costs, and excellent HM uptake efficiency. In this review, we summarize the current state of knowledge on duckweeds and their suitability for HM biomonitoring and phytoremediation. Duckweeds have been used for phytotoxicity assays since the 1930s. Some toxicity tests based on duckweeds have been listed in international guidelines. Duckweeds have also been recognized for their ability to facilitate HM phytoremediation in aquatic environments. Large-scale screening of duckweed germplasm optimized for HM biomonitoring and phytoremediation is still essential. We further discuss the morphological, physiological, and molecular effects of HMs on duckweeds. However, the existing data are clearly insufficient, especially in regard to dissection of the transcriptome, metabolome, proteome responses and molecular mechanisms of duckweeds under HM stresses. We also evaluate the influence of environmental factors, exogenous substances, duckweed community composition, and HM interactions on their HM sensitivity and HM accumulation, which need to be considered in practical application scenarios. Finally, we identify challenges and propose approaches for improving the effectiveness of duckweeds for bioremediation from the aspects of selection of duckweed strain, cultivation optimization, engineered duckweeds. We foresee great promise for duckweeds as phytoremediation agents, providing environmentally safe and economically efficient means for HM removal. However, the primary limiting issue is that so few researchers have recognized the outstanding advantages of duckweeds. We hope that this review can pique the interest and attention of more researchers. [Display omitted] [ABSTRACT FROM AUTHOR]

Duckweed is a widespread type of tiny free-floating plants of the flowering class. A typical representative of the family of the cowhide (Lemnaceae) is a large duckweed (Spirodela polyrhiza) and it is very common on Croatian inland waters. Like all other species of duckweeds, it is characterized by the possibility of vegetative and sexual reproduction and very rapid growth. It has the ability to remove nitrogen, phosphorus and some heavy metals from the substrate and is considered a very desirable raw material for biogas production for several reasons. The necessity of reducing environmental pollution of nitrates from agricultural production and the ability to grow water lenses under eutrophic conditions have sparked this research. The primary objective of the study is to determine the possibilities of continuously growing large duckweed at different concentrations of digestates for the purpose of biogas production. The secondary goal is to determine the dependence between the different digestate concentrations used for the duckweed green mass production and the quantity and quality of the biogas obtained through the anaerobic digestion process at thermophilic conditions.

Plant growth-promoting bacteria (PGPB) can exert beneficial growth effects on their host plants. Little is known about the phylogeny and growth-promoting mechanisms of PGPB associated with aquatic plants, although those of terrestrial PGPB have been well-studied. Here, we report four novel aquatic PGPB strains, MRB1–4 (NITE P-01645–P-01648), for duckweed Lemna minor from our rhizobacterial collection isolated from Lythrum anceps. The number of L. minor fronds during 14 days co-culture with the strains MRB1–4 increased by 2.1–3.8-fold, compared with an uninoculated control; the plant biomass and chlorophyll content in co-cultures also increased. Moreover, all strains possessed an indole-3-acetic acid production trait in common with a plant growth-promoting trait of terrestrial PGPB. Phylogenetic analysis showed that three strains, MRB-1, -3, and -4, were affiliated with known proteobacterial genera (Bradyrhizobium and Pelomonas); this report is the first to describe a plant-growth promoting activity of Pelomonas members. The gammaproteobacterial strain MRB2 was suggested to be phylogenetically novel at the genus level. Under microscopic observation, the Pelomonas strain MRB3 was epiphytic and adhered to both the root surfaces and fronds of duckweed. The duckweed PGPB obtained here could serve as a new model for understanding unforeseen mechanisms behind aquatic plant-microbe interactions.

Deoxynivalenol (DON) is a secondary fungal metabolite that is associated with many adverse toxicological effects in agriculture as well as human/animal nutrition. Bioremediation efforts in recent years have led to the discovery of numerous bacterial isolates that can transform DON to less toxic derivatives. Both 3-keto-DON and 3-epi-DON were recently shown to exhibit reduced toxicity, compared to DON, when tested using different cell lines and mammalian models. In the current study, the toxicological assessment of 3-keto-DON and 3-epi-DON using in planta models surprisingly revealed that 3-keto-DON, but not 3-epi-DON, retained its toxicity to a large extent in both duckweeds (Lemna minor L.) and common wheat (Triticum aestivum L.) model systems. RNA-Seq analysis revealed that the exposure of L. minor to 3-keto-DON and DON resulted in substantial transcriptomic changes and similar gene expression profiles, whereas 3-epi-DON did not. These novel findings are pivotal for understanding the environmental burden of the above metabolites as well as informing the development of future transgenic plant applications. Collectively, they emphasize the fundamental need to assess both plant and animal models when evaluating metabolites/host interactions.

Duckweeds (Lemnaceae) are the smallest and fastest-growing angiosperms. This feature, together with high starch production and good nutritional properties, makes them suitable for several applications, including wastewater treatment, bioenergy production, or feed and food supplement. Due to their reduced morphology and great similarity between diverse species, taxonomic identification of duckweeds is a challenging issue even for experts. Among molecular genotyping methods, DNA barcoding is the most useful tool for species identification without a need for cluster analysis. The combination of two plastid barcoding loci is now considered the gold standard for duckweed classification. However, not all species can be defined with confidence by these markers, and a fast identification method able to solve doubtful cases is missing. Here we show the potential of tubulin-based polymorphism (TBP), a molecular marker based on the intron length polymorphisms of β-tubulin loci, in the genomic profiling of the genera Spirodela, Landoltia, and Lemna. Ninety-four clones were analyzed, including at least two representatives of each species of the three genera, with a special focus on the very heterogeneous species Lemna minor. We showed that a single PCR amplification with universal primers, followed by agarose gel analysis, was able to provide distinctive fingerprinting profiles for 10 out of 15 species. Cluster analysis of capillary electrophoresis–TBP data provided good separation for the remaining species, although the relationship between L. minor and Lemna japonica was not fully resolved. However, an accurate comparison of TBP profiles provided evidence for the unexpected existence of intraspecific hybrids between Lemna turionifera and L. minor, as further confirmed by amplified fragment length polymorphism and sequence analysis of a specific β-tubulin locus. Such hybrids could possibly correspond to L. japonica, as originally suggested by E. Landolt. The discovery of interspecific hybrids opens a new perspective to understand the speciation mechanisms in the family of duckweeds.

With growing human culture and industrialization, many pollutants are being introduced into aquatic ecosystems. In recent years, dyes have become a major water pollutant used in the manufacture of paints and other production purposes. In this research, the potential of duckweed (Lemna gibba) plant was investigated spectrophotometrically as an obvious bioagent for the biological decolorization of the organic dye C.I. Basic Green 4 (Malachite Green, BG4). Photosynthetic efficiency analysis showed that the photosynthetic apparatus of L. gibba is very tolerant to BG4. Significant induction of reactive oxygen species (ROS) scavenging enzymes was observed after 24h of biodecolorization process in L. gibba treated with 15 and 30 mg/l BG4. The experimental results showed that L. gibba has a strong ability to extract BG4 from contaminated water and the best results were obtained at 25–30°C and pH 8.0. We conclude that duckweed L. gibba can be used as a potent decolorization organism for BG4. [ABSTRACT FROM AUTHOR]

Duckweeds (Lemnaceae) are the smallest and fastest-growing angiosperms. This feature, together with high starch production and good nutritional properties, makes them suitable for several applications, including wastewater treatment, bioenergy production, or feed and food supplement. Due to their reduced morphology and great similarity between diverse species, taxonomic identification of duckweeds is a challenging issue even for experts. Among molecular genotyping methods, DNA barcoding is the most useful tool for species identification without a need for cluster analysis. The combination of two plastid barcoding loci is now considered the gold standard for duckweed classification. However, not all species can be defined with confidence by these markers, and a fast identification method able to solve doubtful cases is missing. Here we show the potential of tubulin-based polymorphism (TBP), a molecular marker based on the intron length polymorphisms of β-tubulin loci, in the genomic profiling of the genera Spirodela , Landoltia , and Lemna. Ninety-four clones were analyzed, including at least two representatives of each species of the three genera, with a special focus on the very heterogeneous species Lemna minor. We showed that a single PCR amplification with universal primers, followed by agarose gel analysis, was able to provide distinctive fingerprinting profiles for 10 out of 15 species. Cluster analysis of capillary electrophoresis–TBP data provided good separation for the remaining species, although the relationship between L. minor and Lemna japonica was not fully resolved. However, an accurate comparison of TBP profiles provided evidence for the unexpected existence of intraspecific hybrids between Lemna turionifera and L. minor , as further confirmed by amplified fragment length polymorphism and sequence analysis of a specific β-tubulin locus. Such hybrids could possibly correspond to L. japonica , as originally suggested by E. Landolt. The discovery of interspecific hybrids opens a new perspective to understand the speciation mechanisms in the family of duckweeds. [ABSTRACT FROM AUTHOR]

Duckweeds represent a small, free-floating aquatic family (Lemnaceae) of the monocot order Alismatales with the fastest growth rate among flowering plants. They comprise five genera (Spirodela, Landoltia, Lemna, Wolffiella, and Wolffia) varying in genome size and chromosome number. Spirodela polyrhiza had the first sequenced duckweed genome. Cytogenetic maps are available for both species of the genus Spirodela (S. polyrhiza and S. intermedia). However, elucidation of chromosome homeology and evolutionary chromosome rearrangements by cross-FISH using Spirodela BAC probes to species of other duckweed genera has not been successful so far. We investigated the potential of chromosome-specific oligo-FISH probes to address these topics. We designed oligo-FISH probes specific for one S. intermedia and one S. polyrhiza chromosome (Fig. 1a). Our results show that these oligo-probes cross-hybridize with the homeologous regions of the other congeneric species, but are not suitable to uncover chromosomal homeology across duckweeds genera. This is most likely due to too low sequence similarity between the investigated genera and/or too low probe density on the target genomes. Finally, we suggest genus-specific design of oligo-probes to elucidate chromosome evolution across duckweed genera. [ABSTRACT FROM AUTHOR]

As global population growth and meat consumption increases, sustainable alternatives to conventional protein‐rich fodder crops for livestock are needed to reduce negative environmental impacts. Duckweed, a small floating aquatic plant, can generate 5 to 10 times higher protein yields than conventional land‐grown crops. Although some in vivo feeding trials with duckweed have been conducted, those measuring animal weight are limited, and those examining organ development are nonexistent. To secure broad acceptance of new protein sources, such controlled studies are critical. This study measured the food intake, growth, and final organ and adipose tissue mass of male CF‐1 mice fed a semi‐purified diet containing casein or diets in which 10% or 25% of the casein was replaced with duckweed protein (DWP). Proximate analysis showed that the DWP preparation used contained 39.9% protein (w/w), and contained all of the essential amino acids with Met as the limiting amino acid. The average growth rates were not significantly different among the treatment groups: 0.21 g/day; 0.24 g/day; and 0.25 g/day for the control, 10%, and 25% DWP protein diets, respectively. The daily food intake of both DWP diets was 6.5% to 8.0% higher than the control diet, but feeding efficiency did not differ among diets. The relative weight of the liver, spleen, kidneys, heart, and epidydimal fat, and colon length were not significantly different between treatment groups. The results from this study show that replacement of up to 25% dietary casein with DWP has no adverse effects on the growth rate and final organ and adipose tissue weights of laboratory mice. Practical Application: Duckweed can produce 5 to 10 times more protein per area than land‐grown crops such as soybean. In this study, up to a 25% replacement of casein with duckweed protein had no observable effect on the growth or organ development of laboratory mice. Thus, duckweed has the potential to be used as a protein supplement for livestock, poultry, and fish, thereby decreasing environmental impacts from land‐grown crops used for animal feed. [ABSTRACT FROM AUTHOR]

Duckweeds have been increasingly studied in recent years, both as model plants and in view of their potential applications as a new crop in a circular bioeconomy perspective. In order to select species and clones with the desired attributes, the correct identification of the species is fundamental. Molecular methods have recently provided a more solid base for taxonomy and yielded a consensus phylogenetic tree, although some points remain to be elucidated. The duckweed genus Lemna L. comprises twelve species, grouped in four sections, which include very similar sister species. The least taxonomically resolved is sect. Lemna, presenting difficulties in species delimitation using morphological and even barcoding molecular markers. Ambiguous species boundaries between Lemna minor L. and Lemna japonica Landolt have been clarified by Tubulin Based Polymorphism (TBP), with the discovery of interspecific hybrids. In the present work, we extended TBP profiling to a larger number of clones in sect. Lemna, previously classified using only morphological features, in order to test that classification, and to investigate the possible existence of other hybrids in this section. The analysis revealed several misidentifications of clones, in particular among the species L. minor, L. japonica and Lemna gibba L., and identified six putative ‘L. gibba’ clones as interspecific hybrids between L. minor and L. gibba.

The paper considers technologies for obtaining sorption materials from agricultural processing waste. It is shown that after the separation of valuable components from microalgae and duckweed a large amount of residual biomass is formed, which is a waste. This waste contains cellulose (23.5%), starch, hemicellulose, chitin-and pectin-like substances that cause the sorption properties of biomass. A microstructural analysis of the residual biomass showed a loose surface composed of the tissues of destroyed cells, which proves the high sorption capacity of the residual biomass. The possibility of using residual biomass for wastewater treatment to remove heavy metal ions has been studied and it has been shown that the maximum efficiency of treatment is achieved by residual biomass after heat treatment at 400°C. A unit for obtaining adsorption materials from residual biomass has been developed and created. Economic calculations of the developed installation were made, the payback period is 6 months, and the profit from using this setup is estimated to be $7899 per year. [ABSTRACT FROM AUTHOR]

Aquatic non-targeted organisms are more likely to be exposed to herbicides in multiple pulse events then long continuous exposure. The potential of an organism to recover between exposures has an important role in the overall effects of the toxicant. Common duckweeds show high potential for recovery after a single exposure to isoproturon. To evaluate the growth patterns and recovery potential between multiple exposures, L. minor plants were exposed to isoproturon in three repetitive 7-day treatment cycles in three time-variable exposure scenarios with equivalent time-weighted average concentrations. The growth was significantly inhibited during each exposure phase with significant cumulative effects in every subsequent treatment cycle resulting in a cumulative decrease in biomass production. However, inhibitory effects were reversible upon transferring plants to a herbicide-free nutrient solution. These results indicate that L. minor plants have a high recovery potential even after multiple exposures to isoproturon. Observed cumulative decrease in biomass production, as well as the potential for fast and efficient recovery from repeated herbicide exposure, might affect the competitiveness of L. minor in surface water communities. The observations made during each exposure period, recovery patterns, and the resulting cumulative effects over time may contribute to further development, calibration and validation of mechanistic toxicokinetic/toxicodynamic models for simulating the effects of pesticides on aquatic plants populations in the laboratory and environmental conditions. [ABSTRACT FROM AUTHOR]

An increase in the production and usage of gold nanoparticles (AuNPs) triggers the necessity to focus on their impact on ecosystems. Therefore, the purpose of this study was to investigate the acute toxicity of AuNPs and ionic gold (Au (III)) to organisms representing all trophic levels of the aquatic ecosystem, namely producers (duckweed Lemna minor), consumers (crustacean Daphnia magna, embryos of Danio rerio) and decomposers (bacteria Vibrio fischeri). The organisms were exposed according to a standardized protocol for each species and endpoints. The AuNPs (1.16 and 11.6 d.nm) were synthesized using citrate (CIT) and polyvinylpyrrolidone (PVP) as capping agents, respectively. It was found, that Au (III) was significantly more toxic than AuNPs PVP and AuNPs CIT. AuNPs showed significant toxicity only at high concentrations (mg/L), which are not environmentally relevant in the present time, but a cautious approach is advised, due to the possibility of interactions with other contaminants. [ABSTRACT FROM AUTHOR]

The picture emerging from the rapidly growing literature on host-associated microbiota is that host traits and fitness often depend on interactive effects of host genotype, microbiota, and abiotic environment. However, testing interactive effects typically requires large, multi-factorial experiments and thus remains challenging in many systems. Furthermore, most studies of plant microbiomes focus on terrestrial hosts and microbes. Aquatic habitats may confer unique properties to microbiomes. We grew different populations of duckweed (Lemna minor), a floating aquatic plant, in three microbial treatments (adding no, "home", or "away" microbes) at two levels of zinc, a common water contaminant in urban areas, and measured both plant and microbial performance. Thus, we simultaneously manipulated plant source population, microbial community, and abiotic environment. We found strong effects of plant source, microbial treatment, and zinc on duckweed and microbial growth, with significant variation among duckweed genotypes and microbial communities. However, we found little evidence of interactive effects: zinc did not alter effects of host genotype or microbial community, and host genotype did not alter effects of microbial communities. Despite strong positive correlations between duckweed and microbe growth, zinc consistently decreased plant growth, but increased microbial growth. Furthermore, as in recent studies of terrestrial plants, microbial interactions altered a duckweed phenotype (frond aggregation). Our results suggest that duckweed source population, associated microbiome, and contaminant environment should all be considered for duckweed applications, such as phytoremediation. Lastly, we propose that duckweed microbes offer a robust experimental system for study of host–microbiota interactions under a range of environmental stresses. [ABSTRACT FROM AUTHOR]

Species of Lemnaceae have a high potential for fast biomass production, and this is increasingly gaining attention among researchers in basic plant sciences as well as among entrepreneurs for feed, food and energy production. Hence, the correct identification of the species being used for different duckweed research and applications is becoming indispensable. Here, we present an updated identification key based on morphological markers to the currently accepted 36 species of duckweeds, considering all taxonomic revisions since the publication of the previous key by E. Landolt in 1986. We also provide supplementary morphological characterization and the geographical occurrence of each species of Lemnaceae. [ABSTRACT FROM AUTHOR]

【Objective】The present paper aimed to establish transient expression system of duckweed protoplast to accelerate the development of duckweed bioreactor. 【Method】The protoplast of duckweed was prepared by enzymatic hydrolysis, and a preparation method for the protoplast system of duckweed was established by optimizing and adjusting a series of parameters such as callus type, osmotic pressure and pretreatment method. Then, agrobacteria-mediated exogenous genes were used to enter the callus of duckweed, and the protoplast was prepared to observe the transient expression. By adjusting the parameters of agrobacteria-mediated species, bacterial concentration, acetosyringone concentration and co-culture time, the optimal leaching conditions were selected. Finally, subcellular localization and promoter function verification were carried out by using the transient expression system.【Result】The best conditions for the preparation of the protoplast were as following: the suspension cultured callus of duckweed cultured at 4 °C overnight was used as the preparation material, and enzyme solution(2 % cellulase, 0.5 % macerozyme, 0.5 % pectinase, 0.1 mol/L CaCl2, 0.2 mol/L KCl, 1 % BSA, 20 mmol/L MES pH 5.8, 0.5 mol/L mannitol) was used for digestion at 25 °C for 16 hours(40 r/min). The optimum conditions of agrobacterium tumester culture were as follows: when the concentration of agrobacterium tumester GV301(OD600) was 1 and the concentration of acetosyringone was 100 μmol/L, the callus of the suspension culture had the maximum transformation rate. 【Conclusion】The transient expression system of duckweed protoplast was successfully established, which proved that it could be used for subcellular localization and promoter function verification. [ABSTRACT FROM AUTHOR]

Most theory on the evolution of senescence implicitly assumes that all offspring are of equal quality. However, in addition to age-related declines in survival and fecundity (classically defined senescence), many organisms exhibit age-related declines in offspring quality, a phenomenon known as a parental age effect. Theoretical work suggests that parental age effects may alter age trajectories of selection and therefore shape the evolution of senescence; however, to date, these analyses have been limited to idealized life cycles and models of maternal care in human populations. To gain a broader understanding of how parental age effects may shape age trajectories of selection, we extend the classic age-structured population projection model to also account for parental age structure and apply this model to empirical data from an aquatic plant known to exhibit parental age effects (the duckweed Lemna minor), as well as a diverse set of simulated life cycles. Our results suggest that parental age effects alter predictions from classic theory on the evolution of senescence. Age-related declines in offspring quality reduce the relative value of late-life reproduction, leading to steeper age-related declines in the force of natural selection than would otherwise be expected and potentially favoring the evolution of more rapid rates of senescence. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agriculture & Nature / Kahramanmaraş Sütçü İmam Üniversitesi Tarım & Doğa Dergisi is the property of Kahramanmaras Sutcu Imam Universitesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Premise: Outcomes of species interactions, especially mutualisms, are notoriously dependent on environmental context, and environments are changing rapidly. Studies have investigated how mutualisms respond to or ameliorate anthropogenic environmental changes, but most have focused on nutrient pollution or climate change and tested stressors one at a time. Relatively little is known about how mutualisms may be altered by or buffer the effects of multiple chemical contaminants, which differ fundamentally from nutrient or climate stressors and are especially widespread in aquatic habitats. Methods: We investigated the impacts of two contaminants on interactions between the duckweed Lemna minor and its microbiome. Sodium chloride (salt) and benzotriazole (a corrosion inhibitor) often co‐occur in runoff to water bodies where duckweeds reside. We tested three L. minor genotypes with and without the culturable portion of their microbiome across field‐realistic gradients of salt (3 levels) and benzotriazole (4 levels) in a fully factorial experiment (24 treatments, tested on each genotype) and measured plant and microbial growth. Results: Stressors had conditional effects. Salt decreased both plant and microbial growth and decreased plant survival more as benzotriazole concentrations increased. In contrast, benzotriazole did not affect microbial abundance and even benefited plants when salt and microbes were absent, perhaps due to biotransformation into growth‐promoting compounds. Microbes did not ameliorate duckweed stressors; microbial inoculation increased plant growth, but not at high salt concentrations. Conclusions: Our results suggest that multiple stressors matter when predicting responses of mutualisms to global change and that beneficial microbes may not always buffer hosts against stress. [ABSTRACT FROM AUTHOR]

Lemna sect. Uninerves Hegelm. consists of three species, Lemna minuta Kunth (synonym L. minuscula), L. valdiviana Phil. and L. yungensis Landolt. Lemna yungensis was discovered growing on rocks in the Yungas in Bolivia by E. Landolt and was described just 20 years ago. In the original description, Landolt reported that this species is closely related to L. valdiviana and that it is difficult to distinguish the three species on a morphological basis. Therefore, the taxonomic position and status of L. yungensis remained controversial. Here, we carried out a detailed taxonomic study, integrating approaches that include quantitative morphometry, metabolomic profiling by matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) as well as molecular genetic analysis using amplified fragment length polymorphism (AFLP), and barcoding of plastidic sequences. We also investigated genome sizes of clones of the three species. Whereas L. minuta can easily be differentiated from L. valdiviana and L. yungensis, it was not possible to distinguish L. valdiviana from L. yungensis with any of the methods used. These data imply that L. yungensis is identical to L. valdiviana. Thus, the name L. yungensis should be synonymised with the name L. valdiviana, since this is the older name. [ABSTRACT FROM AUTHOR]

Background: Duckweeds (Lemnaceae) are aquatic plants distributed all over the world. The chloroplast genome, as an efficient solar-powered reactor, is an invaluable resource to study biodiversity and to carry foreign genes. The chloroplast genome sequencing has become routine and less expensive with the delivery of high-throughput sequencing technologies, allowing us to deeply investigate genomics and transcriptomics of duckweed organelles. Results: Here, the complete chloroplast genome of Spirodela polyrhiza 7498 (SpV2) is assembled by PacBio sequencing. The length of 168,956 bp circular genome is composed of a pair of inverted repeats of 31,844 bp, a large single copy of 91,210 bp and a small single copy of 14,058 bp. Compared to the previous version (SpV1) assembled from short reads, the integrity and quality of SpV2 are improved, especially with the retrieval of two repeated fragments in ycf2 gene. There are a number of 107 unique genes, including 78 protein-coding genes, 25 tRNA genes and 4 rRNA genes. With the evidence of full-length cDNAs generated from PacBio isoform sequencing, seven genes (ycf3, clpP, atpF, rpoC1, rpl2, rps12 and ndhA) are detected to contain type-II introns. The ndhA intron has 50% more sequence divergence than the species-barcoding marker of atpF-atpH, showing the potential power to discriminate close species. A number of 37 RNA editing sites are recognized to have cytosine (C) to uracil (U) substitutions, eight of which are newly defined including six from the intergenic regions and two from the coding sequences of rpoC2 and ndhA genes. In addition, nine operon classes are identified using transcriptomic data. It is found that the operons contain multiple subunit genes encoding the same functional complexes comprising of ATP synthase, photosynthesis system, ribosomal proteins, et.al., which could be simultaneously transcribed and coordinately translated in response to the cell stimuli. Conclusions: The understanding of the chloroplast genomics and the transcriptomics of S.polyrhiza would greatly facilitate the study of phylogenetic evolution and the application of genetically engineering duckweeds. [ABSTRACT FROM AUTHOR]

Since effects of alien invasive free-floating plants can be relevant in aquatic ecosystems, we investigated the non-native Lemna minuta impact on four aquatic animal groups: Hydra vulgaris (Coelenterates), Asellus aquaticus (Arthropods), Gambusia affinis (Fish), Bufo bufo tadpoles (Amphibians). An indoor experiment was conducted keeping animals in water held in tanks with L. minuta mats of 0.5 (WI1), 1.5 cm thick (WI2) and without mats (WOU). Water parameters (DO, DO%, pH) and animal responses (survival rate, vitality) were measured every 48 h (0–288 h). Treatments with mats showed significant impacts on animals which were more severe with increasing mat thickness. Strong decreasing of oxygen and pH associated with mat occurrence had a large impact on animals. In WI2 all individuals died within 144 h (H. vulgaris, B. bufo within 96h), while in WI1 there was a higher survival rate and vitality (excluding B. bufo died within 96 h) and in WOU no deaths. This evidence suggests L. minuta thick mats (≥1.5 cm) could have a high impact on animal biodiversity, especially reducing oxygenation level in aquatic ecosystem. [ABSTRACT FROM AUTHOR]

Copyright of Agriculture / Poljoprivreda is the property of Josip Juraj Strossmayer University of Osijek, Faculty of Agriculture in Osijek and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: Recovery of nutrients from water using duckweed and their reuse has significance in closing the loop on nutrient transfer from anthropogenic sources. This study investigated the effect of rate of application and pre-incubation period of duckweed on biomass and nutrient uptake of Swiss chard (Fordhook giant). Methods: Two glasshouse experiments were laid out in randomized complete block designs with three replicates. In the first experiment, Swiss chard was grown on two soils (ferralsol and regosol) amended with Wolffia arrhiza biomass at 0, 50, 100 and 200% of the recommended nitrogen rate. In the second experiment, the same vegetable was grown on the ferralsol amended with W. arrhiza and Lemna minor at recommended nitrogen rate, with pre-incubation periods of 0, 14 and 28 days. Results: Application of W. arrhiza biomass increased Swiss chard dry matter by 23–45% compared to the negative control. The positive control (urea at 100 kg N ha−1 rate) had highest Swiss chard biomass. Higher rates than 100 kg N ha−1 had no added benefit on dry matter accumulation and nitrogen uptake of Swiss chard. Pre-incubation of duckweed for 28 days improved nutrient uptake, resulting in higher dry matter than shorter periods. The Swiss chard dry matter after pre-incubation for 28 days was similar to that from urea application. Conclusion: Findings from this study suggest that duckweed is a resource with beneficial use for nutrient supply to vegetables, especially when appropriate rates are used with pre-incubation. [ABSTRACT FROM AUTHOR]

The effects of polyethylene terephthalate micro-nanoplastics (PET-MNPs) were tested on the model freshwater species Spirodela polyrhiza (L.) Schleid., with focus on possible particle-induced epigenetic effects (i.e. alteration of DNA methylation status). MNPs (size ∼ 200–300 nm) were produced as water dispersions from PET bottles through repeated cycles of homogenization and used to prepare N-medium at two environmentally relevant concentrations (∼0.05 g L−1 and ∼0.1 g L−1 of MNPs). After 10 days of exposure, a reduction in fresh and dry weight was observed in treated plants, even if the average specific growth rate for both frond number and area was not altered. Impaired growth was coupled with a MNP-induced decrease of chlorophyll fluorescence parameters (i.e. ΨET o and Pi abs , indicators of photochemical efficiency) and starch concentration, as well as with alterations in plant ionomic profile and oxidative status. The methylation-sensitive amplification polymorphism (MSAP) technique was used to assess possible changes in DNA methylation levels induced by plastic particles. The analysis showed unusual hypermethylation in 5′-CCGG sites that could be implicated in DNA protection from dangerous agents (i.e. reactive oxygen species) or in the formation of new epialleles. This work represents the first evidence of MNP-induced epigenetic modifications in the plant world. [Display omitted] • PET-MNPs (0.05 and 0.1 g L−1) induced a reduction in S. polyrhiza fresh and dry weight. • Treated plants showed photosynthesis impairment and starch concentration reduction. • Ionome alterations and oxidative stress were induced by PET-MNPs. • MSAP technique revealed MNP-induced DNA hypermethylation. [ABSTRACT FROM AUTHOR]

Duckweeds, or Lemnaceae, are widespread aquatic plants. Morphology-based identification of duckweed species is difficult because of their structural complexity. Hence, molecular tools provide significant advantages for characterizing and selecting species or clones for sustainable commercial use. In this study, we collected and characterized ten duckweed isolates from nine different regions in Saudi Arabia (SA). Based on the morphological characterization and phylogenetic analysis of intergenic spacer sequences of chloroplast DNA using six barcoding markers, the clones were classified into three genera, represented by seven species: Lemna gibba L., Lemna minor L., Lemna japonica Landolt, Lemna aequinoctialis Welw., Lemna perpusilla Torr., Spirodela polyryiza (L.) Schleid., and Landoltia punctate G. Mey. Lemna gibba was revealed to be a distinct dominant duckweed species in many regions of SA. Five barcoding markers showed that L. gibba, L. minor, and L. punctata were the most widely distributed species in the country. However, L. punctata, L. perpusilla, and S. polyryiza were the dominant species in the Al-Qassim, Madinah-1, and Madinah-2 regions, respectively. Moreover, the morphological traits revealed variations for these clones, relative to other studied duckweed clones. According to the results obtained in this study, three out of six plastid markers (trnH-psbA, matK, and atpF-atpH) helped to identify the dominant duckweed species in Saudi Arabia. Further evaluation based on adaptability, molecular genetic studies, and functional genomics is needed for these species to be used at the commercial level in Saudi Arabia.

Duckweeds comprise a distinctive clade of pleustophytic monocots that traditionally has been classified as the family Lemnaceae. However, molecular evidence has called into question their phylogenetic independence, with some authors asserting instead that duckweeds should be reclassified as subfamily Lemnoideae of an expanded family Araceae. Although a close phylogenetic relationship of duckweeds with traditional Araceae has been supported by multiple studies, the taxonomic disposition of duckweeds must be evaluated more critically to promote nomenclatural stability and utility. Subsuming duckweeds as a morphologically incongruent lineage of Araceae effectively eliminates the family category of Lemnaceae that has been widely used for many years. Instead, we suggest that Araceae subfamily Orontioideae should be restored to family status as Orontiaceae, which thereby would enable the recognition of three morphologically and phylogenetically distinct lineages: Araceae, Lemnaceae, and Orontiaceae.

Duckweed has been highlighted as an invaluable resource because of its abilities to remove nitrogen and phosphorus from wastewater coupling with the production of high starch/protein-containing plant biomass. Duckweed recruits microbes and particularly forms a stable "core" bacterial microbiota, which greatly reduces the colonization efficiency of plant growth-promoting bacteria (PGPB). In this study, natural duckweeds were enriched in a sterilized-partially treated wastewater effluent from a poultry farm. After 24 days of cultivation, the duckweed-associated bacteria (DAB) were isolated and evaluated for their plant growth-promoting (PGP) potentials by co-cultivation with axenic Spirodela polyrhiza. Ten species were found in more than one location and could be considered candidates for the stable "core" DAB. Among them, all isolates of Acinetobacter soli, Acidovorax kalamii, Brevundimonas vesicularis, Pseudomonas toyotomiensis, and Shinella curvata increased duckweed growth in Hoagland medium. The highest PGP ability was observed in Sh. curvata W12-8 (with EPG value of 208.72%), followed by Paracoccus marcusii W7-16 (171.31%), Novosphingobium subterraneum W5-13 (156.96%), and Ac. kalamii W7-18 (156.96%). However, the highest growth promotion in the wastewater was observed when co-cultured with W7-16, which was able to increase biomass dry weight and root length of duckweed by 3.17 and 2.26 folds, respectively., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Summary: The fast growth, ease of metabolic labelling and potential for feedstock and biofuels production make duckweeds not only an attractive model system for understanding plant biology, but also a potential future crop. However, current duckweed research is constrained by the lack of efficient genetic manipulation tools. Here, we report a case study on genome editing in a duckweed species, Lemna aequinoctialis, using a fast and efficient transformation and CRISPR/Cas9 tool. By optimizing currently available transformation protocols, we reduced the duration time of Agrobacterium‐mediated transformation to 5–6 weeks with a success rate of over 94%. Based on the optimized transformation protocol, we generated 15 (14.3% success rate) biallelic LaPDS mutants that showed albino phenotype using a CRISPR/Cas9 system. Investigations on CRISPR/Cas9‐mediated mutation spectrum among mutated L. aequinoctialis showed that most of mutations were short insertions and deletions. This study presents the first example of CRISPR/Cas9‐mediated genome editing in duckweeds, which will open new research avenues in using duckweeds for both basic and applied research. [ABSTRACT FROM AUTHOR]

Boron (B) in the irrigation water can be hazardous to human beings and other aquatic or terrestrial organisms when B concentration exceeds a certain level. More importantly, B removal from irrigation water is relatively difficult using conventional processes. In the present experiment, an innovative treatment model based on monoculture and polyculture duckweed wastewater treatment modules was tested for B-rich irrigation water purification and bioelectricity harvesting. Different modules were designed using Lemna gibba L., Lemna minor L., and their combination in order to determine the most optimal duckweed species and vegetation structure for B removal process and bioelectricity generation in a module. In this respect, the module with a monoculture of Lemna gibba achieved the highest net B removal efficiency (71%) when it was exposed to 4 mg/L B (initial concentration). However, B removal efficiencies from all modules decreased when the initial B concentrations reached up to 4 mg/L in the irrigation water. The highest bioelectricity production was measured as 1.04 V with 17783 mWatt/m2 power density at a current density of 44.06 mA/m2 for module with Lemna gibba in monoculture through sacrificial magnesium anode. Specifically, both monocultures and polyculture removed considerable amounts of organic matter from irrigation water. However, biomass production and total chlorophyll (a + b) concentrations of duckweeds significantly decreased when they were exposed to 32 mg/L B in the irrigation water samples. Consequently, our modules present a holistic perspective to the prevention B toxicity problems in agricultural zones, and are a sustainable strategy for farmers or agricultural experts to produce bioelectricity by a cost-effective and eco-technological method. [ABSTRACT FROM AUTHOR]

Aquatic habitats are vulnerable to the invasion of alien species, so early warning protocols are necessary for eradication. The presence in Italy of two alien duckweeds in freshwaters has been documented: Lemna minuta, that showed high invasivity, and L. valdiviana, still confined to south Lazio. These two species may be mistaken for each other and for the domestic L. minor and L. gibba due to morphological variation. Here, we assess the applicability of DNA barcoding as a complement to morphological analysis for monitoring the spread of alien Lemna. We chose two chloroplast genome sequences for their ability to discriminate all Lemna species: the 5' intron of the trnK gene and the matK gene. Among 48 samples of Lemna collected at 20 sites in Central Italy, 20 were identified as L. minor, 19 as L. minuta, five as L. trisulca and four as L. gibba. L. minuta was present at most sampling sites; in particular, at six locations of Lake Trasimeno, eight L. minuta samples were found. We demonstrate that DNA sequence analyses with cost-effective barcoding techniques can effectively support expert efforts in species determination for an early alert system of invasive Lemna species. [ABSTRACT FROM AUTHOR]

Methanotrophs are the only biological sink of the greenhouse gas methane. To understand the ecological features of methanotrophs in association with plants in the methane emitting environments, we investigated the community composition and methane oxidation of methanotrophs associated with duckweeds in a fresh water lake. Duckweeds collected from Lake Biwa, Japan over three summers showed methane consumption activity between 0.0067 and 0.89 μmol h−1 g−1 (wet weight), with the highest values occurring from the end of July to August. The methanotrophic community on duckweeds consisted primarily of γ-proteobacterial groups including the genera Methylomonas and Methylocaldum. Further analysis of co-cultures of a methanotroph isolate with sterilized duckweed revealed that the duckweed plant as well as the duckweed spent culture supernatant exerted an enhancing effect on methane oxidation. These results indicate that duckweeds not only provide a habitat for methanotrophs but also stimulate methanotrophic growth. [ABSTRACT FROM AUTHOR]

Heavy metals phytoextraction potential of swollen duckweed (Lemna gibba Linn.) and lesser duckweed (Lemna aequinoctialis Welw.) was determined under greenhouse conditions by exposing to untreated industrial/municipal effluent for a period of 21 days. The nickel (Ni), lead (Pb), and cadmium (Cd) concentrations in water samples were measured weekly and in plant biomass at the termination of experiments. Significant differences (p < 0.05) between initial and final physicochemical parameters and in heavy metal concentrations of plant and water samples were observed. Periodically measured metal concentrations in mediums revealed that removal percentage was dependent on initial Ni (2.15 mg L-1), Pb (1.51 mg L-1), and Cd (0.74 mg L-1) concentrations. The final metal removal percentages were in the sequence of Ni (97%) > Pb (94%) > Cd (90%) when treated with Lemna gibba L. as compared to control (9-12% reduction). High biomass production of Lemna gibba L. resulted in a large metal reduction in the growth medium and the total plant metal contents were in the sequence of Ni (427 µg) > Pb (293 µg) > Cd (105 µg). The lesser duckweed did not survive under experimental conditions. Based on these results, we concluded that Lemna gibba L. is a good candidate for phytoremediation of wastewater. [ABSTRACT FROM AUTHOR]

Numerous possibilities of Lemnaceae use (biofuel production, supplementation of animal feed, phytoremediation, bioindication) as well as their cheap production and rapid growth offer many novel benefits. The experiment was carried out in laboratory conditions using Spirodela polyrrhiza plants. Plant cultivation was carried out in a phytotron room at 24°C, on the liquid standard "Z" medium which was supplemented with various concentrations of Apol-humus. Plant growth, chlorophyll index, net photosynthesis, transpiration, stomatal conductivity, intercellular CO2 concentration, fresh and dry weight were analysed. The obtained results indicated the beneficial effects of the addition of Apol-humus to the standard Z medium. The designed novel technologies were beneficial for the growth and development of Spirodela polyrrhiza and produced plants with physico-chemical parameters which surpassed those of the control. Rapid growth, a high chlorophyll index, and a far more intensive gas exchange resulted from the presence of fulvic and humic acids as well as chitosan polymers in the medium which originated from Apol-humus and of the substances originating from the waste of methane fermentation. The obtained results confirmed previous assumptions and demonstrated the possibility of obtaining increased biomass of Spirodela plants and also the possibility of using it in biogas plants and for environmental protection. [ABSTRACT FROM AUTHOR]

Background and aims: Aqueous mercury (II), Hg2+, is still nowadays a hazardous pollutant with a large dispersion. Phytoremediation strategies are an environmental friendly and low-cost alternative. In order to improve these processes, Spirodela intermedia, an autochthonous floating macrophyte, was used to remove Hg2+ from mineral water under laboratory conditions, studying the in vivo distribution of mercury and other elements by nuclear microprobe scanning mapping. M&M: Exposures (1 and 10 mg.L-1 Hg2+ concentrations) were performed during at least 2 weeks. All the parameters from the bioremediation process as uptake rate, bioconcentration factors (BCFs) of mercury in roots and leaves and translocation factors (TFs), were achieved from microPIXE quantifications at Buenos Aires Tandar accelerator. Results: For 1 and 10 mg.L-1 concentrations, S. intermedia can be considered as a hyperaccumulator. The highest BCFs (> 1000 in roots and > 200 in leaves) were obtained for 1 mg.L-1 of Hg2+ at 96 h. In all cases TFs < 1 were measured, indicating that Hg2+ translocation is not taking place. High resolution spatial 2D maps of the in vivo distribution for different exposure conditions were established. It was observed that Hg2+ distribution in leaves is more heterogeneous than in roots. An important finding was the detection of Hg in chlorenchyma where its effects are more toxic. Correlation between mercury and calcium distribution and its relationship with physiological responses to intoxication have been examined. Conclusions: Phytoremediation of Hg2+ by S. intermedia is a convenient alternative. Since the protocol was performed using a real water, it becomes an advisable tool at higher scale. [ABSTRACT FROM AUTHOR]

Background: Decreased dietary meat may deplete iron stores, as plant-derived iron bioavailability is typically limited.Objectives: We explored the effect of a low-meat Mediterranean (green-MED) diet, supplemented with Wolffia globosa duckweed (Mankai: rich in protein and iron) as a food source for humans, on iron status. We further examined the iron bioavailability of Mankai in rats.Methods: Two hundred and ninety-four abdominally obese/dyslipidemic [mean age = 51.1 y; body mass index (kg/m2) = 31.3; 88% men] nonanemic participants were randomly assigned to physical activity (PA), PA + MED diet, or PA + green-MED diet. Both isocaloric MED groups consumed 28 g walnuts/d and the low-meat green-MED group further consumed green tea (800 mL/d) and Mankai (100 g green shake/d). In a complementary animal experiment, after 44 d of an iron deficiency anemia-inducing diet, 50 female rats (age = 3 wk; Sprague Dawley strain) were randomly assigned into: iron-deficient diet (vehicle), or vehicle + iso-iron: ferrous gluconate (FG) 14, Mankai 50, and Mankai 80 versions (1.7 mg · kg-1 · d-1 elemental iron), or FG9.5 and Mankai 50-C version (1.15 mg · kg-1 · d-1 elemental iron). The specific primary aim for both studies was changes in iron homeostasis parameters.Results: After 6 mo of intervention, iron status trajectory did not differ between the PA and PA + MED groups. Hemoglobin modestly increased in the PA + green-MED group (0.23 g/dL) compared with PA (-0.1 g/dL; P < 0.001) and PA + MED (-0.1 g/dL; P < 0.001). Serum iron and serum transferrin saturation increased in the PA + green-MED group compared with the PA group (8.21 μg/dL compared with -5.23 μg/dL and 2.39% compared with -1.15%, respectively; P < 0.05 for both comparisons), as did folic acid (P = 0.011). In rats, hemoglobin decreased from 15.7 to 9.4 mg/dL after 44 d of diet-induced anemia. After depletion treatment, the vehicle-treated group had a further decrease of 1.3 mg/dL, whereas hemoglobin concentrations in both FG and Mankai iso-iron treatments similarly rebounded (FG14: +10.8 mg/dL, Mankai 50: +6.4 mg/dL, Mankai 80: +7.3 mg/dL; FG9.5: +5.1 mg/dL, Mankai 50-C: +7.1 mg/dL; P < 0.05 for all vs. the vehicle group).Conclusions: In humans, a green-MED low-meat diet does not impair iron homeostasis. In rats, iron derived from Mankai (a green-plant protein source) is bioavailable and efficient in reversal of anemia. This trial was registered at clinicaltrials.gov as NCT03020186. [ABSTRACT FROM AUTHOR]

• Duckweeds are capable of recovering/extracting nutrients or pollutants by wastewaters. • Lemna phytoremediation efficiency is reduced when mats become overgrown. • Thicker mats limit aerobic decomposition and controls of Escherichia coli abundance. • Abundant necromass belonging to these mats becomes source of nutrients. • Active management interventions are suggested, such as periodic harvesting of duckweeds. Duckweeds are considered suitable plants for bioremediation of wastewaters because they can tolerate and take up diverse pollutants and large quantities of nutrients. They have year-round vegetative growth that can reach very high rates using wastewater nutrients that can accumulate intracellularly or be utilized to produce new biomass. The constructed wetland that services the town of Forano (Central Italy) is composed of three interconnected, but distinct, treatment pools (P1, P2, P3). In this study the phytoremediation performance of the whole treatment system was assessed taking into consideration pH, temperature, oxygen, nitrates, phosphates, sulphates, and pathogenic bacteria (Escherichia coli) at the inlet and outlet of each pool once per season over a year. The remediation efficiency of P2 was lower than in P1 and P3, and this was shown to be due to an extended, dense free-floating Lemna mat. The mat was thick enough (18–30 mm) to block light penetration, and heat and gas exchange to the underlying water resulting in dark, cool and near-anaerobic conditions. These conditions limited aerobic biodecomposition processes and natural control of the E. coli population. The underlying fronds of the Lemna mat in P2 were highly necrotic and became a source of nutrients, shown by an increase in nitrates and phosphates from the inlet to the outlet. Lemna use in phytoremediation is often considered highly important, but it is shown here that active management interventions are required and should involve periodic harvesting of Lemna fronds to avoid mat over-development and formation of necromass. [ABSTRACT FROM AUTHOR]

A 40 days feeding trial with Labeo rohita (rohu) fry was conducted in six outdoor cemented tanks (5m × 4m × 1 m; 6–8 cm soil base) to establish the relative impact of on‐farm grown live Wolffia globosa (a duckweed with crude protein of 28.57%) and a formulated iso‐nitrogenous feed (crude protein 28.37%) on growth performance, survival, health and overall quality of fingerlings. The experimental tanks were dried, limed at 250 kg/ha, filled with ground water and subsequently applied with cow dung (soaked overnight) and mustard oil cake at 1,000 kg/ha and 50 kg/ha respectively. The fry were stocked at 0.3 millions/ha in six prepared tanks, and fed live Wolffia (T1) and formulated feed (T2). Results of the study indicate better performance (p < 0.05) of fry in terms of final mean weight (7.83 g), length (8.82 cm), daily growth index (6.51 g %/day) and survival (89.5%) than those fed on formulated feed. Furthermore, significantly improved (p < 0.05) feed utilization parameters viz. apparent feed conversion ratio (AFCR), apparent protein conversion efficiency (APCE), apparent protein efficiency ratio (APER); haematological parameters viz. total erythrocyte count (TEC), total leucocyte count (TLC), packed cell volume (PCV), plasma glucose and protein of fry were also observed in T1 (live Wolffia). Overall findings from this study hints towards the possible utilization of on‐farm grown live Wolffia as a suitable nutrient source for fry rearing of L. rohita. [ABSTRACT FROM AUTHOR]