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Nitrogen (N) plays an important role in plant growth and developmental metabolic processes, research on nitrogen speciation regulating Cd accumulation in duckweed is still limited. In this study, the effects of three nitrogen sources (NH4Cl, Ca(NO3)2 and NH4NO3) on the growth, Cd accumulation, and photosynthetic parameters of Landoltia punctata (L.punctata) were analyzed. The results showed that Cd enrichment in L. punctata was significantly reduced (p < 0.05) with different nitrogen treatments compared to the control (CK). Ammonium nitrogen (NH4–N) is more conducive to the accumulation of Cd in L. punctata than nitrate nitrogen (NO3–N). The sum of the cell wall components and soluble components of Cd in the NH4–N treatment group was greater than that in the NO3–N treatment group. The proportion of FNaCl extracts in the NH4–N treatment group was greater than in the NO3–N treatment group. NO3–N led to a greater reduction in photosynthetic pigment content than NH4–N. Overall, applying different forms of nitrogen can alleviate Cd toxicity in L. punctata, and the detoxification effect of the NH4–N treatment is stronger than that of NO3–N treatment. This study will provide theoretical and practical support for the application of duckweed in Cd phytoremediation even in eutrophic aquatic environments. NOVELTY STATEMENT: Cd pollution has become a major global public environmental issue. Duckweed is an ideal species to restore Cd-polluted waters due to its fast growth, easy harvesting and hyperaccumulation Cd. Currently, no definite conclusion has been given on the detoxification effect of nitrogen morphology regulating the accumulation of Cd in plant. In this study, the influence of different nitrogen forms on Cd-induced toxicity in Landoltia punctata were revealed through the changes in biomass, Cd subcellular distribution, Cd chemical morphology and photosynthetic pigment. These findings can provide a new way of analyzing the mechanism of Cd enrichment in plants, and also provide theoretical and technical support for the remediation of Cd pollution by using duckweed resources. The Cd-accumulation duckweed can be pyrolyzed to produce biochar, which can not only control the second pollution by decomposed plant bodies but also realizes the efficient use of waste. HIGHLIGHTS: Nitrogen reduced the Cd accumulation in Landoltia punctata due to increased plant biomass. Nitrogen can alter the subcellular distribution and chemical forms of Cd in Landoltia punctata. NH4-N enhanced Cd tolerance of duckweed compared to NO3-N. Lower mobilization of Cd and cell wall combination are the main detoxification strategies for NH4-N supply. [ABSTRACT FROM AUTHOR]

Duckweed, a widely used natural fish feed, has also become more popular as the phytoremediation agent for wastewater, including one sourced from aquaculture. These two features indicate that duckweed can be utilized in a sustainable aquaculture system by treating and reclaiming nutrients from wastewater and then harvesting them for fish feed production. Hence, this study attempted to assess the approach of the two most known duckweed species, i.e., Lemna minor and Spirodela polyrhiza, in depleting NH4 and PO4 from synthetic controlled aquaculture wastewater as well as to understand their yield based on the N:P ratio. Cultivation in synthetic aquaculture wastewater media was carried out, followed by nutrient uptake and growth analysis. According to statistical analysis, both L. minor and S. polyrhiza could remove NH4 and PO4 with a relatively equal rate (p-val > 0.050). Nonetheless, both duckweed species absorb nitrogen more easily than phosphorous (p-val < 0.050). Considering the yield based on nutrient uptake, NH4 drove a more efficient yield for L. minor to S. polyrhiza at 16.70 g dry biomass/g NH4 and 14.14 g dry biomass/g NH4, respectively. Meanwhile, a higher yield was observed on S. polyrhiza than on L. minor regarding PO4 concentration, at 19.31 g dry biomass/g PO4 and 9.10 g dry biomass/g PO4, respectively. Therefore, a strategy to remove nutrients and produce biomass for fish feed can be formulated based on the N:P concentration ratio, where L. minor tends to produce biomass more rapidly in a higher N:P ratio, whereas S. polyrhiza works in the opposite. [ABSTRACT FROM AUTHOR]

The toxicity of nano-sized ZnO particles (nZnO) was evaluated and compared to that of their micro-sized counterparts (mZnO) using an integrative approach to investigate the mechanism of toxicity, utilizing duckweed (Lemna minor) as plant model. Following 7 days of exposure to nZnO or mZnO (2.5, 5, 25, and 50 mg L−1) growth rate, photosynthesis, oxidative stress, and genotoxicity parameters have been determined in duckweed. Phytotoxicity of both ZnO forms at relatively low concentrations was due to the release of free Zn ions into the nutrient media. However, the accumulation of Zn in plants treated with nZnO was significantly higher than in those treated with mZnO. Both mZnO and nZnO significantly reduced growth rate and impaired the functionality of the photosynthetic apparatus as evidenced by structural changes of chloroplasts, a decline in the efficiency of photosystem II, and chlorophyll a content. Additionally, exposure to mZnO and nZnO resulted in the accumulation of reactive oxygen species (ROS), increased lipid peroxidation, the formation of carbonylated proteins, DNA damage, and alterations in antioxidant defense mechanisms. Overall, nZnO caused significantly stronger toxic effects than mZnO. The mechanism of nZnO toxicity to L. minor, as determined by multivariate statistical analysis, involved the disruption of primary photosynthetic reactions due to a redox imbalance in the cell caused by the enhanced absorption of Zn into plant tissues. [ABSTRACT FROM AUTHOR]

Aquaculture plays a substantial role in providing high-quality food globally, as fish serve as a source of protein, minerals, and polyunsaturated fatty acids for human health. Consequently, aquaculture production is steadily increasing. However, there are some challenges including high expense of commercial feed, aquatic pollution, diseases, misuse of antibiotics, and safety of food fish for human health that are concerns for the achievement of sustainable aquaculture production. Therefore, there is a need to explore more options to address these problems. The use of aquatic plants in aquaculture could be the best way to solve these problems and develop sustainable aquaculture production. Aquatic plants, including algae, submerged plants, floating-leaf plants, and emergent plants, offer nutritionally enriched options used in aquaculture as direct feed or feed ingredients. Recent observations indicate that various forms of algae (e.g., nanoparticles, extracts, and pigments) have emerged as promising feed additives in aquaculture. Their application has demonstrated a notable enhancement in the growth performance and survival rates of fishes. This review summarizes the uses of aquatic plants in aquaculture, including (1) direct feeding of fish, (2) use as feed ingredients for fish feed, (3) reduction of water pollution through phytoremediation to improve water quality, and (4) serving as a therapeutic source for disease management. In addition, this article emphasizes the potential of different aquatic plants to solve various problems, including those posed by climate change, in achieving a safe and sustainable aquatic production. [ABSTRACT FROM AUTHOR]

Introduction: The identification of active dietary flavonoids in food is promising for novel drug discovery. The active ingredients of duckweed (a widely recognized food and herb with abundant flavonoids) that are associated with acute myeloid leukemia (AML) have yet to be identified, and their underlying mechanisms have not been elucidated. Objectives: The objective of this study was to identify novel constituents exhibiting antileukemia activity in duckweed through the integration of chemical profiling, network pharmacology, and experimental validation. Methods: First, high performance liquid chromatography‐tandem mass spectrometry (HPLC‐MS/MS) was used to characterize the primary constituents of duckweed. Subsequently, AML cell‐xenograft tumor models were used to validate the anticancer effect of duckweed extract. Furthermore, network pharmacology analysis was conducted to predict the potential active compounds and drug targets against AML. Lastly, based on these findings, two monomers (apiin and luteoloside) were selected for experimental validation. Results: A total of 17 compounds, all of which are apigenin and luteolin derivatives, were identified in duckweed. The duckweed extract significantly inhibited AML cell growth in vivo. Furthermore, a total of 88 targets for duckweed against AML were predicted, with key targets including PTGS2, MYC, MDM2, VEGFA, CTNNB1, CASP3, EGFR, TP53, HSP90AA1, CCND1, MMP9, TNF, and MAPK1. GO and KEGG pathway enrichment analyses indicated that these targets were primarily involved in the apoptotic signaling pathway. Lastly, both apiin and luteoloside effectively induced apoptosis through CASP3 activation, and this effect could be partially reversed by a caspase inhibitor (Z‐VAD). Conclusion: Duckweed extract has an antileukemic effect, and apiin derived from duckweed shows potential as a treatment for AML. A total of 17 compounds, all belonging to apigenin and luteolin derivatives, were identified in duckweed. The antileukemia effect of apiin in duckweed was identified for the first time. Apiin can induce apoptosis in acute myeloid leukemia cells. [ABSTRACT FROM AUTHOR]

Duckweed grown in the water treatment unit of the Nineveh Pharmaceutical Factory contribute to reducing the level of pollution, and are used as a partial substitute for animal protein in common carp fingerling diets, in a growth experiment that lasted for 56 days, where the replacement rates reached 16.67, 33.33, and 50%, that is, a replacement rate, 0%, 2.6%, 5.2%, and 7.8% for treatments T1, T2, T3, and T4 of the total diet, respectively. The results of the statistical analysis showed that the fishes that fed the third diet were significantly superior (P≤0.05) to the other experimental diets in terms of criteria, final weight, total growth, daily gain, relative and specific growth rate, feed intake, feed conversion ratio, feed efficiency ratio, and protein efficiency ratio compared to the control treatment. The results showed that the highest percentage of pollutant removal from the water cleared from the treatment unit was in the spring season, which was represented by both total solids and phosphate compared to the winter and autumn seasons, while the highest percentage of nitrates was in the autumn season. It is clear from what was mentioned above that it is possible to partially replace duckweed with animal protein and that it is effective in reducing pollution of the water discharged from the process unit of the pharmaceutical factory. [ABSTRACT FROM AUTHOR]

Duckweed grown in the water treatment unit of the Nineveh Pharmaceutical Factory contribute to reducing the level of pollution, and are used as a partial substitute for animal protein in common carp fingerling diets, in a growth experiment that lasted for 56 days, where the replacement rates reached 16.67, 33.33, and 50%, that is, a replacement rate, 0%, 2.6%, 5.2%, and 7.8% for treatments T1, T2, T3, and T4 of the total diet, respectively. The results of the statistical analysis showed that the fishes that fed the third diet were significantly superior (P≤0.05) to the other experimental diets in terms of criteria, final weight, total growth, daily gain, relative and specific growth rate, feed intake, feed conversion ratio, feed efficiency ratio, and protein efficiency ratio compared to the control treatment. The results showed that the highest percentage of pollutant removal from the water cleared from the treatment unit was in the spring season, which was represented by both total solids and phosphate compared to the winter and autumn seasons, while the highest percentage of nitrates was in the autumn season. It is clear from what was mentioned above that it is possible to partially replace duckweed with animal protein and that it is effective in reducing pollution of the water discharged from the process unit of the pharmaceutical factory.

Lemna aequinoctialis (duckweed) is the smallest and fast-growing aquatic plant species producing protein-rich biomass with high protein nutritional value, phytoremediation capacity, and nutrient removal from wastewater. Duckweed may also be used as a new potential bioreactor for biological products, such as vaccines, antibodies, and pharmaceutical proteins. Based upon the potential importanc of L. aequinoctialis in phytoremediation and as a bioreactor the aim of this study was to (1) characterize the chemical and nutritional profiles of L. aequinoctialis biomass utilizing an integrated multi-trophic aquaculture system (IMTA) and a pond, and (2) investigate the cytotoxic potential of different concentrations of organic extracts and fractions using the MTT bioassay. EDXRF and ICP-MS analyses indicated the presence of trace elements in lower amounts in relation to the biomass of L. aequinoctialis in the lagoon, emphasizing the importance of plant inclusion management to reduce bioaccumulation of these elements. Analysis of mineral profiles, fatty acids, and amino acids indicated a satisfactory nutritional composition for the use of biomass as a bioproduct. Pigment analysis showed a high concentration of carotenoids, especially astaxanthin. After standardizing the controls, the MTT cell viability test was carried out utilizing rat hepatoma cell line (HTC), which are metabolizing cells that were treated with aqueous or ethanolic extracts and the dichloromethane, ethyl acetate, and methanol fractions at different concentrations. No apparent cytotoxic potential was observed following treatments, since there was no significant reduction in cell viability. Therefore, this study provides information regarding the biomass of L. aequinoctialis derived from the IMTA system, which might support further research into the application of this species as a bioproduct. [ABSTRACT FROM AUTHOR]

Lemna turionifera is native to North America and northern Asia, with significant potential for industrial wastewater remediation. The complete nucleotide sequence of the L. turionifera chloroplast genome (cpDNA) was determined. The cpDNA is a circular molecule of 166,606 bp and containing a pair of inverted repeats (IRs) measuting 31,663 bp each. These IRs are flanked by a small single-copy region of 13,542 bp and a large single-copy region of 89,738 bp. The chloroplast genome of L. turionifera consisted of 112 unique genes, including 78 protein-encoding genes, 30 tRNA genes, and four rRNA genes. The phylogenetic analysis utilizing cpDNA provided a well-supported resolution of the relationships among subfamilies within the Araceae family. Our findings indicated a close relationship between L. turionifera and a clade consisting of L. minor, L. japonica, and L. gibba. The availability of the complete chloroplast genome sequence of L. turionifera presents valuable data for future phylogenetic investigations within the Lemnaceae family.

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

With the increase in the use of paint in industrial areas, the rate of dye in wastewater is also increasing. Therefore, the adsorbents used to remove the dye in wastewater are gaining considerable importance. The potential of duckweed (DW) in adsorption of crystal violet (CV), a water-soluble and toxic organic dye, was investigated. Characterization of the adsorbent was made by FTIR, SEM and pHzpc (zero charge point) analyses, and the pHzpc value was 7.75 pH. The effects of temperature, contact time, initial dye concentration, adsorbent dose and solution pH on CV removal were determined. According to the results obtained, the optimum pH, initial dye concentration, adsorbent dose, temperature and contact time were 6 pH, 30 mg L−1, 0.5 g, 30 ºC and 60 min, respectively. The adsorption data were best fitted with Freundlich isotherm (R2 = 0.9714) and maximum adsorption capacity of 61.06 mg g−1 was determined from the Langmuir isotherm. Adsorption of CV by carbonized duckweed (cDW) follows the pseudo-second-order kinetic model (R2 ≥ 0.999). Thermodynamic results of the adsorption process show that adsorption can occur spontaneously (ΔG0 ≤ -5.302 kJ mol−1) and that the process is endothermic (ΔHº = 5.92 kJ mol−1). The results of this study showed that cDWs are cost-effective adsorbent for effective removal of crystal violet dye. [ABSTRACT FROM AUTHOR]

This study investigates the influence of various parameters on the efficiency of cultivating and preserving Lemna aequinoctialis duckweed samples in vitro, with the aim of minimizing time, labor, and storage expenses. The method addresses the issue of limited space and the risk of sample loss by storing multiple duplicates (more than one tube or flask per sample) in a space-efficient and cost-effective container. Due to the practical implications and capacity to decrease operating expenses, our results are helpful for large-scale implementation. Using a single frond resulted in a longer preservation effect compared to sample densities of three and five fronds. Initial samples can be cultured in nutrient solution with or without sugar, stored in tap water or nutrient solution, kept at a stable temperature of 25 ± 2°C or room temperature. The test tubes with duckweed were not covered, or covered by black paper up to the solution surface or higher. The outcomes demonstrated that all three duckweed samples (HNP_005, HNP_026, and HNP_031), whether grown in SSM or SFM media, were best preserved if the tubes were covered by black paper higher than the solution surface (CH) and can be kept at room temperature for at least 9 mo. [ABSTRACT FROM AUTHOR]

Duckweed is a future food and a source of affordable protein that has the potential to replace animal protein. This study aims to formulate a bio-fertilizer consisting of mangrove-associated bacteria to boost the growth and protein of duckweeds as a sustainable approach to increase plant-based protein yields. The culture-depending technique was performed by using Aleksandrow agar, Pikovskaya's agar, and Jensen agar to screen potassiumsolubilizing bacteria, phosphate-solubilizing bacteria and nitrogen-fixing bacteria, respectively, from mangrove soil sediments. Mangrove-associated bacteria that are close to Acinetobacter radioresistens, Brachybacterium paraconglomeratum, and Enterobacter cloacae, which are known as nitrogen-fixing bacteria, Klebsiella quasipneumoniae, Bacillus tropicus, and Paenibacillus pasadenensis known as potassium-solubilizing bacteria, and Bacillus cereus and Bacillus thuringiensis known as phosphate-solubilizing bacteria were identified through 16S rRNA gene sequencing. After that, three sets of biofertilizers were randomly formulated. Each set consisted of nitrogen-fixing bacteria, potassium- and phosphate-solubilizing bacteria, as well as commercial compost as a carrier. These formulated bio-fertilizers were evaluated for plant growth promotion and protein production on duckweed plants under temperatures between 26 and 30°C. The results showed that each set of our formulated bio-fertilizer can increase the nitrogen (N), phosphorus (P), and potassium (K), duckweed growth, and protein content when compared to the control group. It indicates that bio-fertilizers formulated with mangrove-associated bacteria and high NPK contents could enhance the growth of duckweed as well as its protein content, which could supply our future plant-based protein sustainably. [ABSTRACT FROM AUTHOR]

Premise: In plants, whole‐genome duplication (WGD) is a common mutation with profound evolutionary potential. Given the costs associated with a superfluous genome copy, polyploid establishment is enigmatic. However, in the right environment, immediate phenotypic changes following WGD can facilitate establishment. Metabolite abundances are the direct output of the cell's regulatory network and determine much of the impact of environmental and genetic change on the phenotype. While it is well known that an increase in the bulk amount of genetic material can increase cell size, the impact of gene dosage multiplication on the metabolome remains largely unknown. Methods: We used untargeted metabolomics on four genetically distinct diploid‐neoautotetraploid pairs of the greater duckweed, Spirodela polyrhiza, to investigate how WGD affects metabolite abundances per cell and per biomass. Results: Autopolyploidy increased metabolite levels per cell, but the response of individual metabolites varied considerably. However, the impact on metabolite level per biomass was restricted because the increased cell size reduced the metabolite concentration per cell. Nevertheless, we detected both quantitative and qualitative effects of WGD on the metabolome. Many effects were strain‐specific, but some were shared by all four strains. Conclusions: The nature and impact of metabolic changes after WGD depended strongly on the genotype. Dosage effects have the potential to alter the plant metabolome qualitatively and quantitatively, but were largely balanced out by the reduction in metabolite concentration due to an increase in cell size in this species. [ABSTRACT FROM AUTHOR]

Premise: Polyploidy is a widespread mutational process in angiosperms that may alter population performance of not only plants but also their interacting species. Yet, knowledge of whether polyploidy affects plant–herbivore dynamics is scarce. Here, we tested whether aphid herbivores exhibit preference for diploid or neopolyploid plants, whether polyploidy impacts plant and herbivore performance, and whether these interactions depend on the plant genetic background. Methods: Using independently synthesized neotetraploid strains paired with their diploid progenitors of greater duckweed (Spirodela polyrhiza), we evaluated the effect of neopolyploidy on duckweed's interaction with the water‐lily aphid (Rhopalosiphum nymphaeae). Using paired‐choice experiments, we evaluated feeding preference of the herbivore. We then evaluated the consequences of polyploidy on aphid and plant performance by measuring population growth over multiple generations. Results: Aphids preferred neopolyploids when plants were provided at equal abundances but not at equal surface areas, suggesting the role of plant population surface area in driving this preference. Additionally, neopolyploidy increased aphid population performance, but this result was dependent on the plant's genetic lineage. Lastly, the impact of herbivory on neopolyploid vs. diploid duckweed varied greatly with genetic lineage, where neopolyploids appeared to be variably tolerant compared to diploids, sometimes mirroring the effect on herbivore performance. Conclusions: By experimentally testing the impacts of polyploidy on trophic species interactions, we showed that polyploidization can impact the preference and performance of herbivores on their plant hosts. These results have significant implications for the establishment and persistence of plants and herbivores in the face of plant polyploidy. [ABSTRACT FROM AUTHOR]

Lemna turionifera is native to North America and northern Asia, with significant potential for industrial wastewater remediation. The complete nucleotide sequence of the L. turionifera chloroplast genome (cpDNA) was determined. The cpDNA is a circular molecule of 166,606 bp and containing a pair of inverted repeats (IRs) measuting 31,663 bp each. These IRs are flanked by a small single-copy region of 13,542 bp and a large single-copy region of 89,738 bp. The chloroplast genome of L. turionifera consisted of 112 unique genes, including 78 protein-encoding genes, 30 tRNA genes, and four rRNA genes. The phylogenetic analysis utilizing cpDNA provided a well-supported resolution of the relationships among subfamilies within the Araceae family. Our findings indicated a close relationship between L. turionifera and a clade consisting of L. minor, L. japonica, and L. gibba. The availability of the complete chloroplast genome sequence of L. turionifera presents valuable data for future phylogenetic investigations within the Lemnaceae family. [ABSTRACT FROM AUTHOR]

Vertical oxidation pond operated in sequencing batch mode (HRT: 1.25 day) with duckweed as the vegetation was used to acclimatize with simulated agricultural wastewater. The maximum removal rate of urea [371 g/(m3.d)] and COD [222.4 g/(m3.d)] were observed at moderate concentrations of urea (500 mg/L), N-P-K (60 mg/L), and pesticide (20 mg/L). Inhibition and toxicity posed by higher concentrations, decreased the removals of urea (83% to 61%), COD (81% to 51%), and TDS (76% to 50%) at the end of the acclimatization. Steady removal (> 99%) of PO43−-P was observed during acclimatization. Effluent pH increased due to the generation of NH4+-N (maximum 370 ± 5 mg/L) from the assimilation of urea. Oxidation of ammonia led to the maximum generation of NO2−-N and NO3−-N of 10 mg/L and 9 mg/L, respectively. Particles less than 300 μm increased, and both specific gravity (from 2.62 to 2.42) and maximum dry density (from 1.73 to 1.30 g/cm3) of the base soil decreased with an increase in urea, N-P-K, and pesticide. Reactor biomass increased (1.42 to 1.90 g/L) up to initial concentrations of urea (500 mg/L), N-P-K (60 mg/L), and pesticide (20 mg/L), then decreased (1.68 g/L) with an increase in concentration. [ABSTRACT FROM AUTHOR]

Understanding how competition varies with environmental stress is critical to anticipating species and community responses to rapid environmental change. While the stress‐gradient hypothesis predicts the strength of competition to decrease with increasing stress, our understanding of how competition varies with stress is limited by a lack of mechanistic understanding of how resource‐use traits underlying competitive dynamics respond to stress.Here, we use duckweeds in the Lemna species complex to measure how phenotypic and genetic variation in R* (a resource acquisition trait representing the minimum resource requirement for positive population growth) varies with high‐temperature stress to better understand how stress alters competitive ability for essential resources.We found that heat stress increased the R* of Lemna plants for nitrogen acquisition. Because lower R* values predict dominance in competitive dynamics where resources are limiting, this indicates that under stressful, high temperatures, plants could experience reduced competitive ability due to the higher resources required to sustain positive population growth rates.We found minimal genetic variation in R* across 11 local genotypes within the Lemna species complex, indicating that selection on resource acquisition strategies for essential resources such as nitrogen may be constrained in nature. The expression of genetic variation in R* for nitrogen was further reduced under heat stress, suggesting that the response to selection for R* could be particularly constrained under high‐temperature stress.Contrary to predictions drawn from the gleaner–opportunist trade‐off, we did not find evidence for a trade‐off in resource acquisition strategies under benign conditions or high‐temperature stress. Plants with lower R* (i.e. higher growth rates under lower nitrogen levels) were not constrained to have lower growth rates under higher nitrogen levels, possibly because the chosen genotypes have not diverged across resource acquisition strategies or because Lemna spp. has escaped this constraint.Importantly, our work indicates that high‐temperature stress could increase sensitivity to competition through an increased requirement for resources while reducing the evolutionary potential for Lemna species to respond to selection for resource traits. This study acts as a key step to understanding the mechanistic traits behind competitive dynamics in resource‐limited and stressful environments. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Duckweeds are a widely distributed and economically important aquatic plant family that have high potential for phytoremediation of polluted water bodies. We collected four ecotypes of the common duckweed Lemna minor from the four corners of Switzerland and assessed how their home versus away environments influenced their growth. Additionally, we investigated their response to a metal pollutant (zinc, Zn) in both their home and away environments. Zn is found in freshwater systems and can become harmful to plants at elevated concentrations. We hypothesized that growing in their home environment would help the plants buffer the negative effect of the metal pollutant. To test this, we measured Lemna growth in a common garden experiment in a glasshouse where the four ecotypes were grown in each of the water environments, as well as in three different concentrations of Zn. To investigate whether interactions between Lemna and its microbial community can enhance or reduce tolerance to heavy metal pollution, we sampled chlorophyll‐a as a proxy for algal biomass. Finally, we measured total nitrogen and total organic carbon to describe the abiotic environment in more detail. The four Lemna ecotypes exhibited significantly different growth rates across the water treatments. This difference in fitness was matched with DNA sequencing revealing genetic differentiation between the four ecotypes. However, the effect of the water and Zn treatment on Lemna growth was the same for all ecotypes. We did not find evidence for local adaptation; instead, we observed strong plastic responses. Lemna growth rates were higher under higher Zn concentrations. This positive effect of Zn on Lemna growth could be in part due to reduced competition with algae. We conclude that L. minor ecotypes may exhibit large differences in growth rate, but that the species overall has a high Zn tolerance and strong plastic adaptive potential in novel environments. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the chemical composition of lesser duckweed (Lemna minor L.) obtained from the natural environment and cultured under laboratory conditions. In the fi rst variant, lesser duckweed was  collected from a natural pond (LDN). Subsequently, the plants were cleaned of other aquatic fl ora and fauna, dried, and ground. In the second variant, lesser  duckweed was cultured in an aquarium (LDC) illuminated from 04:00 to 24:00. The water temperature was 25 °C and the pH was maintained in the range of 6.5–7.3. The content of crude protein, fat, and fi bre was similar in LDN and LDC,  but the proportion of crude ash was higher in LDC. The content of total amino acids was 95.70 and 68.71 g/100 g crude protein in LDC and LDN, respectively. The concentrations of essential amino acids and nonessential amino acids were 43.75 and 51.96 g/100 g crude protein in LDC, respectively, and 32.10 and 36.61 g/100 g crude protein in LDN, respectively. Palmitic and stearic acids were found in higher quantities in LDN than LDC, whereas the oleic acid content was three-fold higher  in LDN compared to LDC. Moreover,  linoleic and α-linolenic  acid concentrations were higher in LDN than LDC. Mineral analysis revealed elevated levels of Ca, Na, and Zn, while P and Mg levels were lower in LDC. Additionally, the levels of δ-, γ-tocopherols and α-tocotrienol were found to be  higher in LDC, while δ- and γ-tocotrienols in LDC were below detectable limits.  So, the  signifi cant  infl uence of growth  conditions on the nutrient  composition  of L. minor was shown. Optimizing growth conditions is pivotal for enhancing lesser duckweed production. It seems that L. minor can be a valuable source of essential nutrients and could serve as a supplementary food source for both domestic animals and humans. Nonetheless, anti-nutritional components, including toxic metals, should be monitored. [ABSTRACT FROM AUTHOR]

Duckweeds, including the common duckweed Lemna minor, are increasingly used to test eco‐evolutionary theories. Yet, despite its popularity and near‐global distribution, the understanding of its population structure (and genetic variation therein) is still limited. It is essential that this is resolved, because of the impact genetic diversity has on experimental responses and scientific understanding. Through whole‐genome sequencing, we assessed the genetic diversity and population genomic structure of 23 natural Lemna spp. populations from their natural range in Switzerland. We used two distinct analytical approaches, a reference‐free kmer approach and the classical reference‐based one. Two genetic clusters were identified across the described species distribution of L. minor, surprisingly corresponding to species‐level divisions. The first cluster contained the targeted L. minor individuals and the second contained individuals from a cryptic species: Lemna japonica. Within the L. minor cluster, we identified a well‐defined population structure with little intra‐population genetic diversity (i.e., within ponds) but high inter‐population diversity (i.e., between ponds). In L. japonica, the population structure was significantly weaker and genetic variation between a subset of populations was as low as within populations. This study revealed that L. japonica is more widespread than previously thought. Our findings signify that thorough genotype‐to‐phenotype analyses are needed in duckweed experimental ecology and evolution. [ABSTRACT FROM AUTHOR]

The Somerset Levels and Moors, UK is an area of high conservation value, including nationally and internationally protected wetland sites. Duckweed (Lemna) mats in the Somerset Levels and Moors are increasingly common and are an indication of hyper-eutrophication. Duckweed mats can contribute to increased management burdens and decreases in biodiversity. Research suggests duckweed will thrive in temperate regions as the climate warms. This study investigated the impact of climate warming and eutrophication on duckweed growth in the Somerset Levels and Moors using a previously published model to simulate duckweed growth from the years of 2020–2080. Simulated local climate change projections and adjustments in actual nitrogen and phosphorus levels were used to estimate changes in biomass. Using the simulated data, the model predicted an 83% increase in biomass from the 2020's to the 2070's if nutrients do not change. In order to offset the impact of climate change on duckweed biomass, nutrient levels will need to decrease by more than 50% by 2080. Further changes to management practices will likely be necessary to restore healthy ecological function and biodiversity in the area. [ABSTRACT FROM AUTHOR]

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

Duckweed (Lemnaceae) rises as a crucial model system due to its unique characteristics and wide-ranging utility. The significance of physiological research and phytoremediation highlights the intricate potential of duckweed in the current era of plant biology. Special attention to duckweed has been brought due to its distinctive features of nutrient uptake, ion transport dynamics, detoxification, intricate signaling, and stress tolerance. In addition, duckweed can alleviate environmental pollutants and enhance sustainability by participating in bioremediation processes and wastewater treatment. Furthermore, insights into the genomic complexity of Lemnaceae species and the flourishing field of transgenic development highlight the opportunities for genetic manipulation and biotechnological innovations. Novel methods for the germplasm conservation of duckweed can be adopted to preserve genetic diversity for future research endeavors and breeding programs. This review centers around prospects in duckweed research promoting interdisciplinary collaborations and technological advancements to drive its full potential as a model organism. [ABSTRACT FROM AUTHOR]

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

Background and Aims The duckweeds (Lemnaceae) consist of 36 species exhibiting impressive phenotypic variation, including the progressive evolutionary loss of a fundamental plant organ, the root. Loss of roots and reduction of vascular tissues in recently derived taxa occur in concert with genome expansions of ≤14-fold. Given the paired loss of roots and reduction in structural complexity in derived taxa, we focus on the evolution of the ionome (whole-plant elemental contents) in the context of these fundamental changes in body plan. We expect that progressive vestigiality and eventual loss of roots might have both adaptive and maladaptive consequences that are hitherto unknown. Methods We quantified the ionomes of 34 accessions in 21 species across all duckweed genera, spanning 70 Myr in this rapidly cycling plant (doubling times are as rapid as ~24 h). We related both micro- and macroevolutionary ionome contrasts to body plan remodelling and showed nimble microevolutionary shifts in elemental accumulation and exclusion in novel accessions. Key Results We observed a robust directional trend in calcium and magnesium levels, decreasing from the ancestral representative Spirodela genus towards the derived rootless Wolffia , with the latter also accumulating cadmium. We also identified abundant within-species variation and hyperaccumulators of specific elements, with this extensive variation at the fine (as opposed to broad) scale. Conclusions These data underscore the impact of root loss and reveal the very fine scale of microevolutionary variation in hyperaccumulation and exclusion of a wide range of elements. Broadly, they might point to trade-offs not well recognized in ionomes. [ABSTRACT FROM AUTHOR]

The present study was conducted to find viable and economic ingredients for fish feed by evaluating the effect of partial fish meal replacement with duckweed (Lemna minor) in Gibelion catla feed. Four different isonitrogenous feeds (with 0, 10, 20 and 30% replacement of fish meal with) were prepared and fed to juvenile catla for 60 days at the rate of 5% fish biomass. No significant difference (P>0.05) in fish growth parameters and feed efficiency was observed among the treatments. There was no significant difference in apparent digestibility coefficient (ADC) of dry matter among treatments. Feed ADC (protein) with duckweed at 30% inclusion level was significantly lower (P<0.05) compared to the other treatments. There was no significant difference in muscle composition of fish reared under the four treatments. Results of the present study showed that duckweed can be used to replace up to 20% of fish meal in feed of catla without any negative effect on fish growth or feed digestibility. [ABSTRACT FROM AUTHOR]

In this study, the ecotoxicological effects of a selected OSB material on three model plants (green freshwater algae Desmodesmus subspicatus, duckweed Lemna minor, and seeds of lettuce Lactuca sativa) were tested. A 24 h and 168 h leachate of the same OSB material was prepared. Mg, Si, Ca, K, Fe, Zn, Mn, and Na were found in the samples. Their higher residues were measured in the 168 h leachate. Biogenic elements (N, P, C) were not detected. The acute effect was relatively slow (for algae up to 26%, for duckweed up to 20%, and for lettuce seeds with stimulation up to 37%). Prolongation of the leaching time did not show any effect on the results of the plant tests. Acute toxicity for the three plant species used was slow. [ABSTRACT FROM AUTHOR]

One of the primary sustainability challenges in aquaculture is replacing fish meal with plant‐based ingredients in aquafeeds. Plants are not optimal due to low protein content and antinutritional factors which can cause gut dysbiosis. Duckweed (Lemnaceae) is a family of aquatic plants with high protein content and has been used successfully for various types of animal feeds. In this systematic review and meta‐analysis of 58 papers, we summarize the extent by which duckweed has been used in fish production including the species of fish tested, the grow‐out stage of fish, and method of application. Duckweed studies spanned a total of 18 species of fish (16 freshwater and two marine) that collectively are valued at 263 billion USD annually, and comprise 28% of total aquaculture production by mass. The average experiment length was 72 days (SD 42), primarily at the fingerling life stage. Duckweed was fed to the fish through live grazing, dried, and pelleted forms with 20% inclusion as the most common formulation. The Lemna spp., dominated by L. minor, L. gibba, and unknown Lemna species, were the most commonly used for feeds. Spirodela polyrhiza was the second most common. Duckweed inclusion levels between 15% and 30% were associated with positive outcomes on fish growth and feed conversion ratio without any negative impact on survival rates. Most duckweed species, especially from Wollfiella have not been tested as a fish feed but should be explored whereas most studies focused on freshwater fishes rather than marine. [ABSTRACT FROM AUTHOR]

Dissolved oxygen is fundamental for chemical and biochemical processes occurring in natural waters and critical for the life of aquatic organisms. Many organisms are responsible for altering organic matter and oxygen transfers across ecosystem or habitat boundaries and, thus, engineering the oxygen balance of the system. Due to such Lemna features as small size, simple structure, vegetative reproduction and rapid growth, as well as frequent mass occurrence in the form of thick mats, they make them very effective in oxygenating water. The research was undertaken to assess the impact of various species of duckweed (L. minor and L. trisulca) on dissolved oxygen content and detritus production in water and the role of ecological factors (light, atmospheric pressure, conductivity, and temperature) in this process. For this purpose, experiments were carried out with combinations of L. minor and L. trisulca. On this basis, the content of oxygen dissolved in water was determined depending on the growth of duckweed. Linear regression models were developed to assess the dynamics of changes in oxygen content and, consequently, organic matter produced by the Lemna. The research showed that the presence of L. trisulca causes an increase in dissolved oxygen content in water. It was also shown that an increase in atmospheric pressure had a positive effect on the ability of duckweed to produce oxygen, regardless of its type. The negative correlation between conductivity and water oxygenation, obtained in conditions of limited light access, allows us to assume that higher water conductivity limits oxygen production by all combinations of duckweeds when the light supply is low. Based on the developed models, it was shown that the highest increase in organic matter would be observed in the case of mixed duckweed and the lowest in the presence of the L. minor species, regardless of light conditions. Moreover, it was shown that pleustophytes have different heat capacities, and L. trisulca has the highest ability to accumulate heat in water for the tested duckweed combinations. The provided knowledge may help determine the good habitat conditions of duckweed, indicating its role in purifying water reservoirs as an effect of producing organic matter and shaping oxygen conditions with the participation of various Lemna species. [ABSTRACT FROM AUTHOR]

Salinity negatively impacts soil fertility by impairing the development and physiological functions of foxtail millet plants. Organic amendments have emerged as a viable solution in the reclamation and management of salinity inflicted soils and improve the performance of crop. In this regard, a pot experiment was carried out to examine the effect of organic amendments (OAs) on soil quality and its influence on the growth and physiology of foxtail millet under saline and non-saline condition. The findings indicated that under salt stress conditions, the levels of proline, hydrogen peroxide (H2O2), and electrolyte leakage (EL) risen, whilst other physiological parameters decrease in foxtail millet. However, the addition of OAs, particularly dhaincha and biochar (BC), has shown a promising salt tolerant amendment among others. Its addition improved the growth performance of salinity-stressed plants, including plant height, fresh and dry biomass, simultaneously decreased sodium ion (Na+) and improved calcium (Ca2+), potassium (K+), and nitrate ion (NO3−). They also increased proline build up by 6–17 %, reduced H2O2 (19–38 %) and malondialdehyde (16–18 %). Furthermore, they elevated the relative water content (RWC) (25 %), chlorophyll content, and reduced EL (29–50 %). Once more, dhaincha and BC enhanced the number of rhizobia, phosphorus-solubilizing bacteria (PSB) and overall bacterial population in the soil. In saline soil, daincha and BC could enhance soil organic matter (628 %), total nitrogen (1630 %), available phosphorus (32–38 %), and exchangeable potassium (54–73 %). A potential strategy for improving setaria italica performance under salt is suggested to be the following order, dhaincha > biochar > vermicompost > duckweed. The study would assist stakeholders in these salinity-prone areas in strategizing the use of OAs to their fallow land for cultivation and agricultural activities.

Polyamines (PA) cellular levels are maintained through a balance between synthesis and catabolism, achieved by two classes of enzymes polyamine oxidases (PAOs) and copper amine oxidases (CuAO). Here we investigated the occurrence, molecular evolution and role(s) of PAOs and CuAO gene families in aquatic duckweed and their comparison with other aquatic plants -sea eelgrass, bladderwort, and Lotus. We identified eight bona fide PAO genes (SpPAO1–SpPAO8) and one SpCuAO1 in the greater duckweed genome from three genome assemblies. Interestingly, duckweed PAO genes increased their number through a tandem duplication event, while contrary to this CuAO genes were significantly lost to a single gene SpCuAO1. Phylogenetic analysis revealed that tandemly duplicated SpPAO2–7 share close similarity to well-known terminal catabolism (TC) pathway PAO genes while SpPAO1 and SpPAO8 seem to segregate along with back conversion (BC) participating known PAO genes, suggesting that all tandem duplicated PAOs are involved in TC pathway which is contrary to known trend in land plants where CuAOs are mainly involved in TC pathway. Comparative transcript abundance studies indicated that all eight PAOs and one CuAO gene respond to multiple stresses and principal component analysis identifies SpPAO4 as a highly active gene in response to multiple stresses. Results showed that oxidation of higher polyamines (SPD/SPM) through the TC pathway is diversified in duckweeds. Taken together this study reveals unique insights into the genomic losses and gains of polyamine metabolism possibly involved in achieving the structural and physiological adaptations required for aquatic lifestyle of duckweeds.

Starch serves as the primary energy source for human activities and is utilized as a crucial raw material in various industries. However, due to limited land resources and challenging yield growth, the traditional starch-producing plants are significantly influenced by environmental conditions, which made it unable to meet the demands of population expansion. On the other hand, the traditional source of starch exhibits a relatively stable structure but faces performance limitations that fail to fully meet application requirements. Consequently, structural modifications have been often employed to effectively regulate the performance of starch. Chemical modification is a commonly employed method for controlling performance, but it can pose potential risks to food safety due to the occurrence of chemical reactions caused by limited reagents, residues of chemical auxiliary materials, generation of by-products, and the introduction of new chemical groups into starch molecules. Therefore, the traditional starch resources are inadequate to meet the demands of sustainable development. It is imperative to explore novel starch resources possessing “future characteristics”. According to their characteristics, the sources of future starch could be divided into three categories: firstly, the traditional starch source plants could be genetic breeding or gene edited to achieve directional or site-directed transformation of starch structure, making starch with special application performance; secondly, new starch resources that could overcome the limitations of land and natural environment, or are rich in starch but have not been fully developed and utilized; thirdly, new cell-free synthetic starch that does not take plants and microorganisms as carriers. This review elucidates the necessity, feasibility and development trend of future starch development, and emphasizes on the research status and characteristics of three types of future starch, taking high amylose starch, waxy starch, duckweed starch, microalgae starch, CO2 synthetic starch and polysaccharide biosynthesis starch as examples. This review will provide valuable guidance for future advancements in starch development.

Lemnaceae taxonomy is challenged by the particular morphology of these tiny free-floating angiosperms. Although molecular taxonomy has helped clarify the phylogenetic history of this family, some inconsistency with morphological data leads to frequent misclassifications in the genus Lemna. Recently, the finding that Lemna japonica is an interspecific hybrid between Lemna minor and Lemna turionifera provided a clear explanation for one such taxonomic question. Here we demonstrated that L. minor is also capable of hybridizing with Lemna gibba , generating a cryptic but widespread taxon in the Mediterranean area. The nothotaxon Lemna × mediterranea is described and compared with clones of the putative parental species L. minor and L. gibba. Genetic analysis by nuclear and plastid markers, as well as genome size measurement, revealed that two different cytotypes, diploid and triploid, originated by at least two independent hybridization events. Despite high overall similarity, morphometrical, physiological, and biochemical analyses showed an intermediate position of L. × mediterranea between its parental species in most qualitative and quantitative characters, and also separation of the two hybrid cytotypes by some criteria. These data provide evidence that hybridization and polyploidization, driving forces of terrestrial plant evolution, contribute to duckweed genetic diversity and may have shaped the phylogenetic history of these mainly asexual, aquatic plants. [ABSTRACT FROM AUTHOR]

Using biomass to develop and obtain environmentally friendly and industrially applicable biomaterials is increasingly attracting global interest. Herein, cellulose nanocrystals (CNCs) and lignin nanoparticles (LNPs) were extracted from Lemna minor L., a freshwater free-floating aquatic species commonly called duckweed. To obtain CNCs and LNPs, two different procedures and biomass treatment processes based on bleaching or on the use of an ionic liquid composed of triethylammonium and sulfuric acid ([TEA][HSO4]), followed by acid hydrolysis, were carried out. Then, the effects of these treatments in terms of the thermal, morphological, and chemical properties of the CNCs and LNPs were assessed. The resulting nanostructured materials were characterized by using Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, thermo-gravimetric analysis (TGA), and scanning electron microscopy (SEM). The results showed that the two methodologies applied resulted in both CNCs and LNPs. However, the bleaching-based treatment produced CNCs with a rod-like shape, length of 100–300 nm and width in the range of 10–30 nm, and higher purity than those obtained with ILs that were spherical in shape. In contrast, regarding lignin, IL made it possible to obtain spherical nanoparticles, as in the case of the other treatment, but they were characterized by higher purity and thermal stability. In conclusion, this research highlights the possibility of obtaining nanostructured biopolymers from an invasive aquatic species that is largely available in nature and how it is possible, by modifying experimental procedures, to obtain nanomaterials with different morphological, purity, and thermal resistance characteristics. [ABSTRACT FROM AUTHOR]

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

Duckweed (Lemna minor L.) is a small floating aquatic plant that has an important economic impact in several industrial areas. With its high biomass production, reasonable protein content, and resilience to several climates, it has been attracting increasing interest for potential use in animal and human food systems. Historically consumed in southwest Asia, this duckweed is now gaining attention as a potential novel food in Europe. This manuscript explores the contributions of duckweed to various food and feed industries, including aquaculture and livestock, while also pointing out the incipient research carried out for human consumption. Most importantly, it highlights the potential of Lemna minor as a vegetable for future human consumption whether eaten whole or through extraction of its nutrients. [ABSTRACT FROM AUTHOR]

Ribosomal DNA (rDNA) contains highly conserved, specifically organized sequences encoding ribosomal RNAs (rRNAs) separated by variable nontranscribed intergenic spacers (NTSs) and is abundant in eukaryotic genomes. These characteristics make the rDNA an informative molecular target to study genome organization, molecular evolution, and phylogenetics. In this study, we characterized the 5S rDNA repeats in the greater duckweed Spiroldela polyrhiza, a species known for its small size, rapid growth, highly conserved genome organization, and low mutation rate. Sequence analysis of at least 12 individually cloned PCR fragments containing the 5S rDNA units for each of six ecotypes that originated from Europe (Ukraine) and Asia (China) revealed two distinct types of 5S rDNA repeats containing NTSs of different lengths and nucleotide compositions. The shorter 5S rDNA repeat units had a highly homogeneous 400-bp NTS, with few ecotype-or region-specific singlenucleotide polymorphisms (SNPs). The longer 5S rDNA units had NTSs of 1056-1084 bp with characteristic intra- and inter-genomic variants due to specific SNPs and insertions/deletions of 4-15-bp DNA elements. We also detected significant variability in the ratio of short/long 5S rDNA variants between ecotypes of S. polyrhiza. The contrasting dynamics of the two types of 5S rDNA units, combined with the unusually low repeat copy number (for plants) in S. polyrhiza (46-220 copies per genome), shows that this species could serve as an excellent model for examining the mechanisms of concerted evolution and functional significance of rDNA variability. [ABSTRACT FROM AUTHOR]

Lemna aequinoctialis Welw. is a widely spread species that has diverse physiological and molecular properties. Flower characteristics are important factors in deducing taxonomical status; however, owing to the rarity of flowering observations in Lemna, studying them has been a prolonged challenge. In this study, physiological and morphological analyses were conducted by inducing flowering, and molecular analysis was done based on the two chloroplast DNA loci (matK, atpF−atpH intergeneric spacer) of L. aequinoctialis sensu Landolt (1986) from 70 strains found in 70 localities in Japan, Korea, Thailand, and the US. In total, 752 flowering fronds from 13 strains were observed based on axenic conditions. Two different trends in flower organ development—protogyny and adichogamy—were detected in these strains. Their physiological traits were divided into two groups, showing different morphological features based on frond thickness, root cap, and anther sizes. Molecular analysis showed two lineages corresponding to two physiological groups. These were identified as L. aequinoctialis sensu Beppu et al. (1985) and L. aoukikusa Beppu et Murata based on the description of the nomenclature of L. aoukikusa. These were concluded as independent taxa and can be treated as different species. Furthermore, the distribution of L. aoukikusa is not only limited to Japan. [ABSTRACT FROM AUTHOR]

Promoters are one of the most critical elements in regulating gene expression. They are considered essential biotechnological tools for heterologous protein production. The one most widely used in plants is the 35S promoter from cauliflower mosaic virus. However, our study for the first time discovered the 35S promoter reduced the expression of exogenous proteins under increased antibiotic stress. We discovered an endogenous strong promoter from duckweed named LpSUT2 that keeps higher initiation activity under antibiotic stress. Stable transformation in duckweed showed that the gene expression of eGFP in the LpSUT2:eGFP was 1.76 times that of the 35S:eGFP at 100 mg.L-1 G418 and 6.18 times at 500 mg.L-1 G418. Notably, with the increase of G418 concentration, the gene expression and the fluorescence signal of eGFP in the 35S:eGFP were weakened, while the LpSUT2:eGFP only changed slightly. This is because, under high antibiotic stress, the 35S promoter was methylated, leading to the gene silencing of the eGFP gene. Meanwhile, the LpSUT2 promoter was not methylated and maintained high activity. This is a previously unknown mechanism that provides us with new insights into screening more stable promoters that are less affected by environmental stress. These outcomes suggest that the LpSUT2 promoter has a high capacity to initiate the expression of exogenous proteins. In conclusion, our study provides a promoter tool with potential application for plant genetic engineering and also provides new insights into screening promoters. [ABSTRACT FROM AUTHOR]

Three photoperiods designed as 24L:0D; 0L:24D and 12L:12D were used to culture Hoplobatrachus occipitalis (Günther 1858) tadpoles to evaluate the growth performance and survival rate. One hundred and eighty tadpoles were distributed into the three photoperiodic ponds for 20 weeks and fed with duck weed. The frogs reared using the 0L:24D photoperiod had significantly higher growth performance, survival rate and metamorphosis where the tadpoles reached full metamorphosis after 20 weeks, than the other two photoperiods (P <.05.) Full metamorphosis of the tadpoles was seen when the limbs have been fully formed, tails and gills have been completely absorbed, the eyes become bulgy and they are completely out of water breathing by their lungs. Higher growth performance, survival rate and metamorphosis in 0L:24D photoperiod could be attributed to complete utilization of food, low ammonia concentration and high dissolved oxygen. Commercial aquaculture of H. occipitalis tadpoles should be done in 0L:24D to obtain complete metamorphosis, survival and faster growth in less time. Using 0L:24D to culture the tadpoles and releasing them into the wild will decrease overexploitation of the species, thereby aiding in their conservation. [ABSTRACT FROM AUTHOR]

Synthetic colorants are widely used globally by different industries for the dyeing process. However, these chemicals pollute the environment and affect human health by causing allergies, hives, dermatitis, and cancer. This study aims to compare the effectiveness of duckweed (Lemna minor) in the removal of the Methylene Blue (MB) and Congo red (CR) dyes at different concentrations (1 mg/L, 5 mg/L, 10 mg/L, and 15 mg/L). Absorbance values were determined at 665 nm for MB and 497 nm for CR after 96 hours. The results show higher removal of MB compared to CR for all concentrations (95.49 % vs. 59.32%, 1 mg/L; 97.24% vs. 39.43%, 5mg/L; 91.30% vs 28.47%, 10mg/L; y 85.42% vs 20.27%, 15mg/L). The removal of MB was observed after 30 min of contact with duckweed, while the removal of CR was observed after 24 hours in all concentrations. [ABSTRACT FROM AUTHOR]

The global demand for protein is on the rise owing to the exponential increase in the world population and to meet the global protein requirements, it is imperative to seek alternative sources of proteins in farm animal feeding. Recognizing the importance of proteins and the fact that a major portion of human protein requirements is derived from livestock in the form of meat, milk, and eggs, the available protein-feeding stuff in the form of soybean meal cannot be regarded as sufficient for feeding to livestock. Oil seeds such as rapeseed meal and canola meal have a crude protein content of 30%-40% and are widely used and hence a potential alternative protein source to soybean meal. Going forward, Grain legumes such as peas, faba beans, and lupins, another alternative source of proteins have the potential to replace traditional protein feeds completely or partially such as bone and fish meals. Duckweed with a protein content of 20%-45% is another plant-based potential protein source that can be employed in livestock feeding particularly pigs owing to its huge potential as a growth promoter as evidenced by studies in pigs and piglets. Because of their nutritional qualities and possible environmental advantages, insects represent another class of alternative protein sources that have enormous potential to function as sustainable protein sources. Several insect species have been assessed for use as animal feeds; the most promising ones include the yellow mealworm (Tenebrio molitor, TM), the common house fly (MD), and the black soldier fly (Hermetia illucens, HI). Byproducts from aquaculture and fisheries are abundant in macro- and micronutrients, and their utilisation can provide fishmeal and fish oil, which can then be further adapted for use as a source of protein in animal nutrition. Employing microalgae as an alternative source of protein in animal feeding is somehow a new concept. Many nutritional and toxicological studies have demonstrated the potential of algae biomass as a valued feed supplement or substitute for conventional protein sources such as soybean meal. While these alternative protein sources in livestock feeding may serve as useful tools, parameters such as feed safety and acceptability should be monitored based on feed safety regulations. [ABSTRACT FROM AUTHOR]

Duckweeds are among the fastest reproducing plants, able to clonally divide at exponential rates. However, the genetic and epigenetic impact of clonality on plant genomes is poorly understood. 5-methylcytosine (5mC) is a modified base often described as necessary for the proper regulation of certain genes and transposons and for the maintenance of genome integrity in plants. However, the extent of this dogma is limited by the current phylogenetic sampling of land plant species diversity. Here we analyzed DNA methylomes, small RNAs, mRNA-seq, and H3K9me2 histone modification for Spirodela polyrhiza. S. polyrhiza has lost highly conserved genes involved in de novo methylation of DNA at sites often associated with repetitive DNA, and within genes, however, symmetrical DNA methylation and heterochromatin are maintained during cell division at certain transposons and repeats. Consequently, small RNAs that normally guide methylation to silence repetitive DNA like retrotransposons are diminished. Despite the loss of a highly conserved methylation pathway, and the reduction of small RNAs that normally target repetitive DNA, transposons have not proliferated in the genome, perhaps due in part to the rapid, clonal growth lifestyle of duckweeds. [ABSTRACT FROM AUTHOR]

Wolffia globosa is a small free-floating aquatic plant native to the Southeast Asia and invasive in Europe. Between the years 2017 and 2022 it has been found in Czechia for the first time in this country in wetland habitats at seven sites. Occurrences of alien W. globosa were first recorded in the Central Bohemia region inside the Site of Community Importance Libické luhy, then by two sewage treatment plants and one adjacent fishpond in South Bohemia and in the Elbe River near the cities of Přelouč, Lysá and Labem, Obříství and Hřensko. At four sites, W. globosa has been recorded in flowing waters for the first time in Europe. The mode of introduction remains unknown. [ABSTRACT FROM AUTHOR]

A significant number of emerging pollutants resulting from point and diffuse pollution can be found in the aquatic environment. Pharmaceuticals, including antidepressants, are increasingly consumed across the world. Their good water solubility and resistance to biodegradation are major challenges to wastewater treatment. Pharmaceuticals enter aquatic systems mainly with wastewater via wastewater treatment plants. These emerging contaminants can be removed by introducing biological cleaning systems with plants that grow near secondary wastewater units. This study analyzed the ability of Lemna minor to bioaccumulate four antidepressants: sertraline (SER), fluoxetine (FLU), paroxetine (PAR), and mianserin (MNS). A significant decrease in drug concentrations was observed in the samples with L. minor in comparison with those without plants. Among the tested drugs, L. minor showed the greatest bioaccumulation potential for SER, and the lowest for FLU. The bioconcentration factor for MNS never exceeded 100 L kg–1 even after 7 days, while for SER it was 1,902 L kg–1. These results indicate that L. minor can influence the water treatment process in the natural ecosystem and serve as an effective tool in wastewater treatment for the removal of the analyzed antidepressants. [ABSTRACT FROM AUTHOR]

Duckweeds span 36 species of free-floating aquatic organisms with body sizes ranging from 2 mm to 10 mm, where each plant body plan is reduced to a largely leaf-like structure. As an emerging crop, their fast growth rates offer potential for cultivation in closed systems. We describe a novel UK collection derived from low light (dLL) or high light (dHL) habitats, profiled for growth, photosynthesis, and photoprotection (non-photochemical quenching, NPQ) responses. Twenty-three accessions of three Lemna species and one Spirodela polyrhiza were grown under relatively low light (LL: 100 μmol m–2 s–1) and high light (HL: 350 μmol m–2 s–1) intensities. We observed broad within- and between-species level variation in photosynthesis acclimation. Duckweeds grown under HL exhibited a lower growth rate, biomass, chlorophyll, and quantum yield of photosynthesis. In HL compared with LL, carotenoid de-epoxidation state and NPQ were higher, whilst PSII efficiency (φPSII) and Chl a : b ratios were unchanged. The dLL plants showed relatively stronger acclimation to HL compared with dHL plants, especially Lemna japonica accessions. These achieved faster growth in HL with concurrent higher carotenoid levels and NPQ, and less degradation of chlorophyll. We conclude that these data support local adaptation to the light environment in duckweed affecting acclimation in controlled conditions. [ABSTRACT FROM AUTHOR]

Understanding non-target-site resistance (NTSR) to herbicides represents a pressing challenge as NTSR is widespread in many weeds. Using giant duckweed (Spirodela polyrhiza) as a model, we systematically investigated genetic and molecular mechanisms of diquat resistance, which can only be achieved via NTSR. Quantifying the diquat resistance of 138 genotypes, we revealed an 8.5-fold difference in resistance levels between the most resistant and most susceptible genotypes. Further experiments suggested that diquat uptake and antioxidant-related processes jointly contributed to diquat resistance in S. polyrhiza. Using a genome-wide association approach, we identified several candidate genes, including a homolog of dienelactone hydrolase, that are associated with diquat resistance in S. polyrhiza. Together, these results provide new insights into the mechanisms and evolution of NTSR in plants. [ABSTRACT FROM AUTHOR]

The inclusion of protein in the regular human diet is important for the prevention of several chronic diseases. In the search for novel alternative protein sources, plant-based proteins are widely explored from a sustainable and ecological point of view. Duckweed (Lemna minor), also known as water lentil, is an aquatic plant with potential applications for human consumption due to its protein content and carbohydrate contents. Among all the conventional and novel protein extraction methods, the utilization of ultrasound has attracted the attention of scientists because of its effects on improving protein extraction and its functionalities. In this work, a Box–Behnken experimental design was proposed to optimize the alkaline extraction of protein from duckweed. In addition, an exploration of the effects of ultrasound on the morphological, structural, and functional properties of the extracted protein was also addressed. The optimal extraction parameters were a pH of 11.5 and an ultrasound amplitude and processing time of 60% and 20 min, respectively. These process conditions doubled the protein content extracted in comparison to the value from the initial duckweed sample. Furthermore, the application of ultrasound during the extraction of protein generated changes in the FTIR spectra, color, and structure of the duckweed protein, which resulted in improvements in its solubility, emulsifying properties, and foaming capacity. [ABSTRACT FROM AUTHOR]