Duckweed Research Articles

БІОМОРФОЛОГІЧНА ХАРАКТЕРИСТИКА РОДУ LEMNA L. РОДИНИ LEMNACEAE GREY. В ІНТРОДУКЦІЇ

The results of the research of biomorphological characteristic of Lemna L. ofLemnaceae. Grey. family of the collection O. V. Fomin Botanical garden are shown.The family is presented by 3 genera (Lemna L., Spirodela Schleid.,Wolffia Horkel ex Schleid.) and 6 species. Genus Lemna L.contains 4 species. Thecomparative characteristic of the main features of the introduced representatives ofLemna genus was carried out. For the first time phenospectres has been presented,where the longest, medium and shortest seasonal vegetative development of eachspecies are noted.Their taxonomical diversity, ecobiomorphological features,geographycal distribution, conditions, methods of the inroduction and practical useare observed.It is shown that according to the results of the study of bioecologicalcharacteristics of the family Lemnaceae, Lemna genus in the collection of theBotanical Garden named after. acad. O. V. Fomin has 4 species. The taxonomy ofgenera, geographic distribution, life form, biomorphological peculiarities in theconditions of introduction, methods of care, reproduction and practical use are given.For the given systems the family belongs to the class Monocotyledones, Arales order.By its biomorphological characteristic it is perennial, grassy, aquatic plants. All ofthem have floating on the surface or in the water of the leaf, in L. turionifera they arepapillomas and form, in September, turions. The comparative table of thecharacteristics of the main features of the introduced species is presented: form,length (mm), leaf coloring, number of veins, presence of anthocyanins and theformation of turions. For the first time, eight phenosperms of seasonal vegetativedevelopment of introduced species are presented. It is proved in the article thatcultivation methods in protected and open ground contribute to the maintenance oftropical and subtropical species of the genus, for which, in our conditions, we uselimiting, floating plastic foam plastic and immersed, plastic, transparent, containers.Key words: Lemna, distribution, biomorphology, introduction.

Linkage structure of cell-wall polysaccharides from three duckweed species

Rapid growth and easily digestible walls that are naturally low in lignin make the aquatic plant family Lemnaceae, or duckweed, a promising feedstock for biofuel production. Monosaccharide and linkage analysis of cell walls from three species of duckweed: Spirodela polyrhiza, Lemna gibba, and Wolffia australiana showed that apiogalacturonans and/or xylogalacturonans, and smaller amounts of rhamnogalacturonan I, constituted 57%, 51% and 48% of their respective wall mass. Hemicellulosic xylan, xyloglucan, and glucomannan made up lesser amounts wall mass across the three species. Apiose residues were either non-reducing terminal or 3′-linked, but their ratios varied substantially from nearly 1:1 for S. polyrhiza and 2:1 for L. gibba, to 10:1 for W. australiana. These findings will help guide future research to design efficient strategies for disassembly of duckweed cell walls into sugars and uronic acids for conversion of duckweed biomass into usable fuel, and to facilitate extraction of other bioproducts from its polysaccharides.

Post-transcriptional adaptation of the aquatic plant Spirodela polyrhiza under stress and hormonal stimuli.

The Lemnaceae family comprises aquatic plants of angiosperms gaining attention due to their utility in wastewater treatment, and rapid production of biomass that can be used as feed, fuel, or food. Moreover, it can serve as a model species for neotenous growth and environmental adaptation. The latter properties are subject to post-transcriptional regulation of gene expression, meriting investigation of how miRNAs in Spirodela polyrhiza, the most basal and most thoroughly sequenced member of the family, are expressed under different growth conditions. To further scientific understanding of its capacity to adapt to environmental cues, we measured miRNA expression and processing of their target sequences under different temperatures, and in the presence of abscisic acid, copper, kinetin, nitrate, and sucrose. Using two small RNA sequencing experiments and one degradome sequencing experiment, we provide evidence for 108 miRNAs. Sequencing cleaved mRNAs validated 42 conserved miRNAs with 83 targets and 24 novel miRNAs regulating 66 targets and created a list of 575 predicted and verified targets. These analyses revealed condition-induced changes in miRNA expression and cleavage activity, and resulted in the addition of stringently reviewed miRNAs to miRBase. This combination of small RNA and degradome sequencing provided not only high confidence predictions of conserved and novel miRNAs and targets, but also a view of the post-transcriptional regulation of adaptations. A unique aspect is the role of miR156 and miR172 expression and activity in its clonal propagation and neoteny. Additionally, low levels of 24nt sRNAs were observed, despite the lack of recent retrotransposition.

Comparative evaluation and kinetics of biogas yield from duckweed (<i>Lemna minor</i>) co-digested with water hyacinth (<i>Eichhornia crassipes</i>)

Anaerobic co-digestion of duckweed (DW) with water hyacinth (WH) at five DW: WH ratios (1:0, 7:3, 1:1, 3:7 and 0:1 w: w dry basis) was carried out with a view to comparing and evaluating the effect on biogas yield. Fixed quantity of cow dung slurry was added to each treatment as inoculum to seed the digesters before digestion for seventeen weeks in batch type digesters. Biodegradation and maximum biogas yield models based on first-order kinetics were fitted to the experimental biogas yields to describe the cumulative and predict maximum biogas yields, respectively from each treatment. The results indicated that DW was viable for biogas production and more prolific than WH. Co-digestion did not affect (p > 0.05) temperature and pH but affected (p ≤ 0.05) total bacterial count and biogas yield. The high R2 values obtained from the biodegradation model fit showed that the model described the experimental yields satisfactorily. Furthermore, the high R2 values and percentages of predicted maximum yield/observed maximum yield showed that the maximum biogas yield model predicted the maximum yields satisfactorily. The study concluded that co-digestion of DW and WH was best at ratio 7:3 while ratio 1:1 was the best described and predicted by the biodegradation and maximum biogas yield models.

Creation of culture media for efficient duckweeds micropropagation (Wolffia arrhiza and Lemna minor) using artificial mathematical optimization models

Recently, computer technologies have provided the researchers with the new approaches for modeling and better understanding the role of the factors that are involved in plant growth in vitro. To develop new models for the optimization of growth conditions, it is reasonable to use plants with a high speed of vegetative in vitro reproduction, such as duckweed (Lemnaceae family). This article focuses on the trophic levels of the two types of duckweeds (Wolffia arrhiza and Lemna minor). Using the development of the optimal modeling of the biological processes we have obtained the prescriptions for individually-balanced culture medium that enable 3.0 higher yields of the total soluble protein from each of the populations for both types of Lemnaceae.

Genomes and Transcriptomes of Duckweeds.

Duckweeds (Lemnaceae family) are the smallest flowering plants that adapt to the aquatic environment. They are regarded as the promising sustainable feedstock with the characteristics of high starch storage, fast propagation, and global distribution. The duckweed genome size varies 13-fold ranging from 150 Mb in Spirodela polyrhiza to 1,881 Mb in Wolffia arrhiza. With the development of sequencing technology and bioinformatics, five duckweed genomes from Spirodela and Lemna genera are sequenced and assembled. The genome annotations discover that they share similar protein orthologs, whereas the repeat contents could mainly explain the genome size difference. The gene families responsible for cell growth and expansion, lignin biosynthesis, and flowering are greatly contracted. However, the gene family of glutamate synthase has experienced expansion, indicating their significance in ammonia assimilation and nitrogen transport. The transcriptome is comprehensively sequenced for the genera of Spirodela, Landoltia, and Lemna, including various treatments such as abscisic acid, radiation, heavy metal, and starvation. The analysis of the underlying molecular mechanism and the regulatory network would accelerate their applications in the fields of bioenergy and phytoremediation. The comparative genomics has shown that duckweed genomes contain relatively low gene numbers and more contracted gene families, which may be in parallel with their highly reduced morphology with a simple leaf and primary roots. Still, we are waiting for the advancement of the long read sequencing technology to resolve the complex genomes and transcriptomes for unsequenced Wolffiella and Wolffia due to the large genome sizes and the similarity in their polyploidy.

Retrospective analyses of archive phytotoxicity test data can help in assessing internal dynamics and stability of growth in laboratory duckweed cultures

High growth potential of duckweed species (Lemnaceae family) has been utilized in wide range of research and practical applications. Based on literature data, however, it can be assumed that duckweed populations maintain constant growth rates only when short periods are considered but can vary over longer time scales. This intrinsic instability in growth can affect the interpretation of growth data. Duckweed phytotoxicity tests are usually performed according to highly standardized protocols. Therefore the archive data provide an opportunity for retrospective comparisons. In the present study we collected growth (frond number- and frond area-based relative growth rates) and morphology (average frond and colony sizes) data from control treatments of phytotoxicity tests. All the analyzed tests were carried out with the same Spirodela polyrhiza (L.) Schleid. (giant duckweed) clone (RDSC ID No. 5501) under the same experimental conditions over more than four years. We aimed to assess the overall variability of the above parameters and to test if intrinsic growth patterns affect growth data in short-term. In general, the results reflected high stability of the measured parameters in long term but also indicated that some temporal variability is inevitable which can bias the comparability of growth tests. The frond area-based relative growth rate resulted in smaller coefficient of variation than the usually preferred frond number-based one. The results also revealed a negative correlation between mean growth rates and their coefficients of variation. Therefore, it would be advisable to introduce higher minimal growth rates and/or maximized tolerable coefficients of variation for control cultures into the standard duckweed growth inhibition tests. Analyses of growth data aggregated on seasonal basis indicated faster growth and larger mean frond size in laboratory duckweed cultures from mid-autumn till mid-spring than during summer and early autumn. But, in shorter term (∼50 days) we did not observe distinct trends in growth suggesting that the successive frond generations have no effect on growth traits within this time-scale. Our results point to the importance of assessing intrinsic growth dynamics in duckweed cultures and also to the re-usability of the already collected phytotoxicity data in addressing new research questions.

Assessment of Mycelia Extract from Trichoderma harzianum for its Antifungal, Insecticidal and Phytotoxic Importance

Trichodermaharzianum was cultured on potato dextrose broth media at 20°C in an incubator and mycelial cells were extracted with ethyl acetate to obtain the organic extract for in-vitro bio-activities including antifungal, insecticidal and phytotoxicity. Different strains of fungal pathogens including Aspergillusflavus, Rhizopusstolonifer and Pythiumultimum were used to assess the antifungal potential of T. harzianum extract. The inhibitory effect was found 82% for A. flavus , 77% for P. ultimum and 73% for R. stolonifer when compared with positive and negative control experiments. Aphids (Macrosiphumrosae ) as a test insects were used to perform the insecticidal activity that showed potent activity with LC50 (38.88 µgml-1). The herbicidal potential was evaluated against duck weed (Lemna minor ) which showed that by using very high concentration (1000 µgml-1) only 60% lethality was achieved. This pilot study revealed that the organic extract obtained from T. harzianum contains useful compounds having potential to be utilized in the development of fungicides and pesticides for the improvement of agricultural sector of the country.

Fate of estrone in laboratory-scale constructed wetlands

A horizontal, subsurface, laboratory-scale constructed wetland (CW) consisting of four cells in series was used to determine the attenuation of the steroid hormone estrone (E1) present in animal wastewater. Liquid swine manure diluted 1:80 with farm pond water and dosed with [14C]E1 flowed through the series of cells containing floating vegetation (duckweed, family Lemnaceae) and a sand:gravel sediment layer. The aqueous layer within each cell was sampled across time, and at 168h duckweed and sediment were sampled for E1 and/or its metabolites. Control and Blank systems consisted of single cells with no vegetation or no vegetation/sediment, respectively. Only 5% of the dose was detected in the effluent at 168h. With the use of mass spectrometry and thin layer chromatography, it was determined that E1 was metabolized into estriol (E3) and to polar metabolites. The largest compartment for [14C] was duckweed (42.1% of administered dose) at 168h followed by sediment (17.3%) and the liquid layer (15.1% of the dose). Most of the vegetative removal of E1 occurred in the first cell, and thereafter, sediment:liquid layer interactions governed E1 movement suggesting particle-bound transport on either colloids or dissolved organic matter. Horizontal, subsurface flow CW were able to remove approximately 95% of the influent E1, and demonstrated the importance of vegetative matter in removal of this potent steroid hormone.

Toxicity of 56 substances to trees.

Toxicity data of substances to higher plants is needed for the purpose of risk assessment, site evaluation, phytoremediation, and plant protection. However, the results from the most common phytotoxicity tests, like the OECD algae and Lemna test, are not necessarily valid for higher terrestrial plants. The willow tree toxicity test uses inhibition of transpiration (aside of growth and water use efficiency) of willow cuttings grown in spiked solutions or soils as end point to quantify toxicity. This overview presents results from 60 studies including 24 new unpublished experiments for 56 different chemicals or substrates. Highest toxicity (EC50<1mg/L) was observed from exposure to heavy metals like copper and cadmium. Also, organotins and free cyanide showed very high toxicity. The toxic effect of chlorophenols on willows was comparable to that on duck weed (Lemna) and green algae, while volatile compounds like chlorinated solvents or benzene, toluene, ethylbenzene, and xylene had less effect on trees than on these aquatic plants, due to volatilization from leaves and test media. In particular low (g/L range) toxicity was observed for tested nanomaterials. Effects of pharmaceuticals (typically weak acids or bases) depended strongly of the solution pH. Like for algae, baseline toxicity was observed for willows, which is related to the water solubility of the compounds, with absolute chemical activity ranging from 0.01 to 0.1, but with several exceptions. We conclude that the willow tree toxicity test is a robust method for relating uptake, accumulation, and metabolism of substances to the toxicity to trees.

Evaluation of environmental bacterial communities as a factor affecting the growth of duckweed Lemna minor

BackgroundDuckweed (family Lemnaceae) has recently been recognized as an ideal biomass feedstock for biofuel production due to its rapid growth and high starch content, which inspired interest in improving their productivity. Since microbes that co-exist with plants are known to have significant effects on their growth according to the previous studies for terrestrial plants, this study has attempted to understand the plant–microbial interactions of a duckweed, Lemna minor, focusing on the growth promotion/inhibition effects so as to assess the possibility of accelerated duckweed production by modifying co-existing bacterial community.ResultsCo-cultivation of aseptic L. minor and bacterial communities collected from various aquatic environments resulted in changes in duckweed growth ranging from −24 to +14% compared to aseptic control. A number of bacterial strains were isolated from both growth-promoting and growth-inhibitory communities, and examined for their co-existing effects on duckweed growth. Irrespective of the source, each strain showed promotive, inhibitory, or neutral effects when individually co-cultured with L. minor. To further analyze the interactions among these bacterial strains in a community, binary combinations of promotive and inhibitory strains were co-cultured with aseptic L. minor, resulting in that combinations of promotive–promotive or inhibitory–inhibitory strains generally showed effects similar to those of individual strains. However, combinations of promotive–inhibitory strains tended to show inhibitory effects while only Aquitalea magnusonii H3 exerted its plant growth-promoting effect in all combinations tested.ConclusionSignificant change in biomass production was observed when duckweed was co-cultivated with environmental bacterial communities. Promotive, neutral, and inhibitory bacteria in the community would synergistically determine the effects. The results indicate the possibility of improving duckweed biomass production via regulation of co-existing bacterial communities.

Nutrient scaling of duckweed ( Spirodela polyrhiza ) biomass in urban wastewater and its utility in anaerobic co-digestion

Abstract The study aimed to investigate the biochemical up gradation of duckweed (DW)—Spirodela polyrhiza biomass cultivated in wastewater and then its further utility in anaerobic digestion (AD). For chemical scaling of DW biomass, a batch-scale duckweed reactor was designed using urban wastewater (WW) and changes in WW characteristics were recorded at the end. The WW showed the significant reduction (p T2 (15.13) > T3 (9.55). Results thus, revealed that the high content of DW in reactor caused positive effect on methane generation. During the process, soluble chemical oxygen demand (SCOD) and volatile solids (VS) also reduced 36.8–79.7% and, 42.9–70.9%, respectively. Gompertz model validates the experimental methane yield in all setups. Our study indicates that DW can be sustainable tool to solve two major problems: wastewater treatment and renewable energy production under clean development approach.

Effect of thermal pre-treatment on co-digestion of duckweed (Lemna gibba) and waste activated sludge on biogas production

The duckweeds (DW) are considered as a major problem in tropical aquatic system as they grow very fast and produce enormous rich-biomass, which can be harvested for renewable energy operations. But complex lignocellulosic compounds limit their utility in process like anaerobic digestion. This batch study aimed to analyse characteristics (proximate, ultimate and physico-chemical) and possible utility of DW for anaerobic co-digestion with waste activated sludge (WAS) under mesophilic conditions for 35 d. Two sets of experiment were tested: substrate with and without thermal pre-treatment. Five combinations of DW: WAS (70:20, 60:20, 50:20, 40:20 and 30:20%) were established and biomethanation along with changes in pH, volatile solids (VS), volatile fatty acids (VFAs), and soluble chemical oxygen demand (sCOD) of digestate were recorded. The total CH4 yield (mL CH4 g−1 VS) ranged between 60 and 468 for pre-treated, and 9 and 76 for non-pre-treated. The maximum CH4 yield was 468 mL CH4g−1 VS in DW: WAS (50:20). Thermally treated setups, showed about 13-, 24.1-, 21.1-, 1.4-, and 2.3-fold higher CH4 than non-treated setups. The treated mixtures showed high reduction of SCOD (>41–96) and VS (>59–98%) in co-digesters. The high degree of Gompertz curve fitting (R2 > 0.99) has suggested pre-treatment of substrate for optimal outputs of co-digester. Based on results obtained, it is suggested that DW (50–60% in digester) can be used as renewable energy resource for biomethanation process after thermal pre-treatment.

Textile dye removal using experimental wetland ponds planted with common duckweed under semi-natural conditions

The study assesses the performance of experimental wetland pond systems vegetated by Lemna minor L. (common duckweed or lesser duckweed) for textile azo dye removal. The objectives are to assess the influence of L. minor on water quality parameters, compare the dye and chemical oxygen demand (COD) removal of four dyes (Acid Blue 113, Reactive Blue 198, Direct Orange 46 and Basic Red 46) with each other, and monitor the effect of dye accumulation as a function of the relative growth rate (RGR) of L minor. Findings indicate that the simulated shallow pond systems remove BR46 (low concentration) significantly (p < 0.05) higher than other dyes, and the ponds containing L. minor outperformed control ponds by around 51% in mean removal efficiency with a potential of L. minor for phytoremediation of approximately 13% efficiency. (Less)

Response of duckweed to lead exposure: phytomining, bioindicators and bioremediation

Response of duckweed to lead exposure: phytomining, bioindicators and bioremediation

Chemical control of duck weed and its effect on water quality and residue

Chemical control of duck weed and its effect on water quality and residue

An assessment of duckweed as a potential lignocellulosic feedstock for biogas production

Due to the complicated structure of lignocellulosic plant cell wall, their utilization for biogas production via anaerobic digestion has not been widely adopted. Alternative to this is to use aquatic plant materials as feedstock for biogas production. In this context, duckweed, an aquatic plant may prove to be a promising new energy source for bioenergy as well efficient CO2 sequestration. This study entails a detailed characterization of duckweed to evaluate their potential as an alternate feedstock to cattle dung for biogas production. The duckweed was characterized for volatile matter, moisture content, ash content and carbon, hydrogen, and nitrogen (CHN) content. Property analysis of duckweed was also done by Fourier transform spectroscopy and thermogravimetric analysis. The volatile matter of duckweed was found to be 84.24± 0.2% with a lignin content of 12.2%, which is very encouraging for biogas production. Co-digestion of duckweed (DW) with cattle dung (CD) in varying ratios (DW:CD = 90:10, 75:25, and 50:50 respectively) in batch type anaerobic digesters was performed at 37 °C temperature for 55 days. The cumulative biogas production for CD (100%), DW/CD (90:10), (75:25) and (50:50) was found to be 11,620, 305, 11,695, and 12,070 mL, respectively, which indicated that duckweed can be a potential lignocellulosic feedstock when co-digested with cattle dung at an optimum ratio of 1:1. Methane content of the biogas from co-digested feedstock is comparable to the biogas from cattle dung alone.

Resurgence of duckweed research and applications: report from the 3rd International Duckweed Conference.

Duckweed, flowering plants in the Lemnaceae family, comprises the smallest angiosperms in the plant kingdom. They have some of the fastest biomass accumulation rates reported to date for plants and have the demonstrated ability to thrive on wastewater rich in dissolved organic compounds and thus could help to remediated polluted water resources and prevents eutrophication. With a high quality genome sequence now available and increased commercial interest worldwide to develop duckweed biomass for renewables such as protein and fuel, the 3rd International Duckweed Conference convened at Kyoto, Japan, in July of 2015, to update the community of duckweed researchers and developers on the progress in the field. In addition to sharing results and ideas, the conference also provided ample opportunities for new-comers as well as established workers in the field to network and create new aliances. We hope this meeting summary will also help to disseminate the key advances and observations that have been presented in this conference to the broader plant biology community in order to encourage increased cross-fertilization of ideas and technologies.

Comparative study on growth performance of Thai Sharpunti (Puntius gonionotus) using two different weeds Duck weed (Lemna minor) and Azolla fern (Azolla pinneta)

The comparative growth performance study of Thai Sharpunti (Puntius gonionotus) was conducted from 20th March to 18th May, 2012by using duck weed (Lemna minor ) and Azolla fern (Azolla pinneta ) as in earthen pondof the Department of Aquaculture, Bangladesh Agricultural University, Mymensingh. Duck weed and Azolla fern were supplied as dietary feed in two separate treatments and each with three replications. Fifteen fingerlings of Thai sharputi was stocked in each pond. Average size and weight of Thai sarputi were 5.75 cm and 21g in T1 and 5.50 cm and20g in T2, respectively. The ranges of physico-chemical parameters viz, water temperature (25.00 to 33.500C), air temperature (31.00 to 34.500C), transparency (28 to 34 cm),dissolved oxygen (6.00 to 7.20 mg/l), free CO2 (2.00 to 3.33 mg/l), pH (6.9 to 7.45), total alkalinity (48 to 61 mg/l), phosphate-phosphorus (1.40 to 2.50 mg/l) and nitrate-nitrogen (2.13 to 3.20 mg/l) were within the productive range. Initial body weight, final body weight, weight gain, survival rate, specific growth rate(SGR), food convertion ratio (FCR), percent weight gain, average daily gain (ADG) were observed as21 and 20g, 356g and 308g, 335 and 288g, 90 and 85%, 558and 480% per day, 5.28 and 6.10, 1595 and 1440%, 5.58 and 4.80g in both the treatments,respectively. Calculated gross and net fish production in T1 with duck weed were 2.40 and 2.08 ton/ha/yr and in T2 with Azolla fern were 2.26 and 1.94 ton/ha/yr, respectively. It was found that the net fish production in T1 was 1.32 times higher than T2 (P?0.01, 0.05). The present study showed influence of duck weed as dietary feed on the production of Thai Sharpunti (P. gonionotus ) was positively significant. So it might be concluded that duckweed had better effect as dietary feed than Azolla fern on monoculture of Thai sharpunti.Res. Agric., Livest. Fish.2(2): 369-374, August 2015

Element-specific downward fluxes impact the metabolism and vegetation of kettle holes

Given that water-filled kettle holes are mostly undergo a wet–dry cycle, and are directly fuelled by terrigenous material, it was hypothesized that the downward flux of matter, including P and its binding partners, varies between and within kettle holes, and is closely coupled to the prevalent water regime. Sedimentation was studied in two kettle holes close to Rittgarten (RG) and Kraatz (KR), Uckermark, NE Germany. Pairs of cylindrical traps at three sites in each kettle hole were sampled biweekly (June 2013–July 2014). Mean fluxes decreased with decreasing water level. KR was Fe-dominated binding P, and had submersed macrophytes. RG was Ca dominated and had low Fe concentrations suggesting that both apatite and oxidized Fe compounds equilibrated P release, with finally a surplus in P. Thus, RG was covered by duck weed. The higher C flux fuelled the sulphate reduction at higher rates than in KR, as also favoured by oxygen deficits due to duck weed coverage. Thus, internal eutrophication, i.e. where sulphate reduction and Fe sulphide formation lead to a lower Fe availability for P binding, is an issue for kettle holes increasingly degrading their ecosystem services.