Changes in bioactive compounds and antioxidant activity of three Amaranthus L. genotypes from a model to household processing.

Amaranthus L. leaves are consumed as vegetables and are a rich source of secondary plant metabolites. The phenolic profiles of the three analyzed genotypes by LC-Q-TOF-MS/MS and HPLC-DAD were characterized by high amounts of hydroxycinnamic glucaric and -isocitric acids. 'Gartenfuchsschwanz' (A. hybridus L.) and 'Red Callaloo' (A. tricolor L.) had similar profiles. 'Gemüse-Amaranth' (A. tricolor L.) had a high amount of caffeoylglucaric acid 4, which was isolated, and afterward identified by NMR. Its antioxidant activity, measured by TEAC, DPPH, and TPC, was similar to 5-caffeoylquinic acid, common in many plant species. The antioxidant activity of Amaranthus L. can be explained rather by their different phenolic- and ascorbic acid concentrations than by their species. Household cooking reduces antioxidant activity due to oxidation processes while leaching into cooking water could be neglected. Amaranthus L. baked into a wheat-dough-matrix showed lower phenolic concentrations, presumably due to the formation of phenol-protein-bounds and thermal degradation.

Characterization of the Phenolic Compounds in Different Plant Parts of Amaranthus cruentus Grown under Cultivated Conditions.

Phenolic compounds that are present in amaranth crops have gained a lot of interest from researchers due to their health benefits potential. Therefore, the aim of this study was to investigate phenolic compounds present in different plant parts of Amaranthuscruentus using liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry. Moreover, data were analyzed by one-way analysis of variance of the statistical analysis software, whereas commercial statistical package version 4.02 was used for principal component analysis. A total of 21 phenolic compounds were detected and eight were not identified. Caffeoylsaccharic acid isomer, coumaoryl saccharic acid, tryptophan, feruloyl-d-saccharic acid isomer a, b, and c, caffeoyl isocitrate, quercetin 3-O-rhamnosyl-rhamnosyl-glucoside, feruloyl isocitrate, hyperoside, kaempferol rutinoside, and alkaloid compounds were mostly detected in tender and mature leaves. Generally, rutin content was higher (p < 0.05) in most vegetative parts of the amaranth plant, thus, late maturity leaves, tender leaves, and mature leaves, respectively. Lower quantities of rutin were observed in tender grains, flowers, and mature grains. It can be concluded that amaranth contains phenolic compounds, predominantly in the vegetative parts, which makes it to be a promising source of phenolic compounds beneficial to human health.

Red beet (Beta vulgaris) and amaranth (Amaranthus sp.) microgreens: Effect of storage and in vitro gastrointestinal digestion on the untargeted metabolomic profile.

This study aimed to investigate the combined effect of storage at 4 °C (10-days) and in vitro gastrointestinal digestion on the phytochemical profile of red beet (Beta vulgaris) and amaranth (Amaranthus sp.) microgreens. The untargeted profiling based on UHPLC-QTOF metabolomics allowed annotating 316 compounds, comprising mainly polyphenols and lipids. An impact of storage on the total phenolic content (TPC) was observed, with a maximum increase at 10-days of storage for both red beet (+1.3-fold) and amaranth (+1.1-fold). On the other hand, in vitro digestion of both red beet and amaranth microgreens produced a significant increase in TPC (36-88%), CUPRAC (27-40%), DPPH (6-43%), and BC (41-57%) to reach the maximum at 10 days of storage. Tyrosinase inhibitory potential also decreased following digestion. The combination of biochemical changes occurring in microgreen immature plants (likely in response to the harvest stress) with changes during digestion, determined the actual functional value of microgreens.

Natural diversity of hydroxycinnamic acid derivatives, flavonoid glycosides, carotenoids and chlorophylls in leaves of six different amaranth species.

Amaranth species are globally grown food crops. However, knowledge about the composition of their secondary metabolites is insufficient. Here, selected hydroxycinnamic acid derivatives, flavonoid glycosides, carotenoids and chlorophylls in the leaves of 14 genotypes from six different amaranth species were identified and quantified. For the first time, caffeic acid esters of isocitric and several aldaric acids were isolated and quantified in a leafy food matrix. High concentrations of hydroxycinnamic acid derivatives and chlorophylls, and moderate amounts of flavonoids and carotenoids were detected. A hierarchical clustering method of the metabolic profiles followed by Random Amplification of Polymorphic DNA (RAPD)-PCR fingerprinting was used to group the genotypes. Using this combined approach, three main groups of amaranth species were assigned. The information provided in this study increases the attractiveness of the amaranth genus as a food crop due to its strong diversity of plant secondary metabolites that are associated with numerous health-promoting benefits.

A peptide derived from enzymatic digestion of globulins from amaranth shows strong affinity binding to the replication origin of Tomato yellow leaf curl virus reducing viral replication in Nicotiana benthamiana.

Tomato yellow leaf curl virus (TYLCV; genus Begomovirus; family Geminiviridae) infects mainly plants of the family Solanaceae, and the infection induces curling and chlorosis of leaves, dwarfing of the whole plant, and reduced fruit production. Alternatives for direct control of TYLCV and other geminiviruses have been reported, for example, the use of esterified whey proteins, peptide aptamer libraries or artificial zinc finger proteins. The two latter alternatives affect directly the replication of TYLCV as well as of other geminiviruses because the replication structures and sequences are highly conserved within this virus family. Because peptides and proteins offer a potential solution for virus replication control, in this study we show the isolation, biochemical characterization and antiviral activity of a peptide derived from globulins of amaranth seeds (Amaranthus hypochondriacus) that binds to the replication origin sequence (OriRep) of TYLCV and affects viral replication with a consequent reduction of disease symptoms in Nicotiana benthamiana. Aromatic peptides obtained from papain digests of extracted globulins and albumins of amaranth were tested by intrinsic fluorescent titration and localized surface resonance plasmon to analyze their binding affinity to OriRep of TYLCV. The peptide AmPep1 (molecular weight 2.076 KDa) showed the highest affinity value (Kd = 1.8 nM) for OriRep. This peptide shares a high amino acid similarity with a part of an amaranth 11S globulin, and the strong affinity of AmPep1 could be explained by the presence of tryptophan and lysine facilitating interaction with the secondary structure of OriRep. In order to evaluate the effect of the peptide on in vitro DNA synthesis, rolling circle amplification (RCA) was performed using as template DNA from plants infected with TYLCV or another begomovirus, pepper huasteco yellow vein virus (PHYVV), and adding AmPep1 peptide at different concentrations. The results showed a decrease in DNA synthesis of both viruses at increasing concentrations of AmPep1. To further confirm the antiviral activity of the peptide in vivo, AmPep1 was infiltrated into leaves of N. benthamiana plants previously infected with TYLCV. Plants treated with AmPep1 showed a significant decrease in virus titer compared with untreated N. benthamiana plants as well as reduced symptom progression due to the effect of AmPep1 curtailing TYLCV replication in the plant. The peptide also showed antiviral activity in plants infected with PHYVV. This is the first report, in which a peptide is directly used for DNA virus control in plants, supplied as exogenous application and without generation of transgenic lines.

Relating sensory profiles of canned amaranth (Amaranthus cruentus), cleome (Cleome gynandra), cowpea (Vigna unguiculata) and Swiss chard (Beta vulgaris) leaves to consumer acceptance.

BACKGROUND: The younger generation of South Africans generally do not consume traditional meals prepared using African green leafy vegetables, primarily because they are regarded as bitter, "poverty" foods. Canning of these vegetables could create value-added products that can be sold in the commercial market. Descriptive sensory evaluation and consumer acceptance testing with young females were used to assess the potential of such products. RESULTS: The sensory attributes of amaranth, cleome and cowpea leaves canned in brine and in a cream sauce were described using 21 attributes grouped by aroma, taste, texture/mouthfeel and aftertaste. Amaranth and Swiss chard products were described as sweet with a popcorn-like aroma. Cleome products were described as bitter, sour, pungent, chemical-tasting, astringent, sandy with a metallic mouthfeel and strong aftertaste. Cowpea products were described as having woody and tobacco aromas as well as a chewy and cohesive texture. Among the products canned with a cream sauce, young female consumers preferred amaranth and Swiss chard; cowpea was less liked, while cleome was least liked. CONCLUSIONS: Canned amaranth leaves have potential as a commercial product that may be well liked by young consumers. The cowpea leaves product has consumer potential, but the formulation needs revision, while canned cleome leaves need further research work. © 2017 Society of Chemical Industry.

Indigenous leafy vegetables of Eastern Africa - A source of extraordinary secondary plant metabolites.

Indigenous African leafy vegetables vary enormously in their secondary plant metabolites whereat genus and the species have a great impact. In African nightshade (Solanum scabrum), spiderplant (Cleome gynandra), amaranth (Amaranthus cruentus), cowpea (Vigna unguiculata), Ethiopian kale (Brassica carinata) and common kale (Brassica oleracea) the specific secondary metabolite profile was elucidated and gained detailed data about carotenoids, chlorophylls, glucosinolates and phenolic compounds all having an appropriate contribution to health beneficial properties of indigenous African leafy vegetables. Exemplarily, various quercetin glycosides such as quercetin-3-rutinoside occur in high concentrations in African nightshade, spiderplant, and amaranth between ~1400-3300µg/g DW. Additionally the extraordinary hydroxycinnamic acid derivatives such as glucaric isomers and isocitric acid isomers are found especially in amaranth (up to ~1250µg/g DW) and spiderplant (up to 120µg/g DW). Carotenoids concentrations are high in amaranth (up to101.7µg/g DW) and spiderplants (up to 64.7µg/g DW) showing high concentrations of ß-carotene, the pro-vitamin A. In contrast to the ubiquitous occurring phenolics and carotenoids, glucosinolates are only present in the Brassicales species Ethiopian kale, common kale and spiderplant characterized by diverse glucosinolate profiles. Generally, the consumption of a variety of these indigenous African leafy vegetables can be recommended to contribute to different benefits such as antioxidant activity, increase pro-vitamin A and anticancerogenic compounds in a healthy diet.

Differential genomic arrangements in Caryophyllales through deep transcriptome sequencing of A. hypochondriacus.

Genome duplication event in edible dicots under the orders Rosid and Asterid, common during the oligocene period, is missing for species under the order Caryophyllales. Despite this, grain amaranths not only survived this period but display many desirable traits missing in species under rosids and asterids. For example, grain amaranths display traits like C4 photosynthesis, high-lysine seeds, high-yield, drought resistance, tolerance to infection and resilience to stress. It is, therefore, of interest to look for minor genome rearrangements with potential functional implications that are unique to grain amaranths. Here, by deep sequencing and assembly of 16 transcriptomes (86.8 billion bases) we have interrogated differential genome rearrangement unique to Amaranthus hypochondriacus with potential links to these phenotypes. We have predicted 125,581 non-redundant transcripts including 44,529 protein coding transcripts identified based on homology to known proteins and 13,529 predicted as novel/amaranth specific coding transcripts. Of the protein coding de novo assembled transcripts, we have identified 1810 chimeric transcripts. More than 30% and 19% of the gene pairs within the chimeric transcripts are found within the same loci in the genomes of A. hypochondriacus and Beta vulgaris respectively and are considered real positives. Interestingly, one of the chimeric transcripts comprises two important genes, namely DHDPS1, a key enzyme implicated in the biosynthesis of lysine, and alpha-glucosidase, an enzyme involved in sucrose catabolism, in close proximity to each other separated by a distance of 612 bases in the genome of A. hypochondriacus in a convergent configuration. We have experimentally validated that transcripts of these two genes are also overlapping in the 3' UTR with their expression negatively correlated from bud to mature seed, suggesting a potential link between the high seed lysine trait and unique genome organization.

Chromium Accumulation in Medicinal Plants Growing Naturally on Tannery Contaminated and Non-contaminated Soils.

Herbal preparations used to treat human ailments globally can be contaminated with various heavy metals (HMs) originating from the raw materials or from the manufacturing processes. Therefore, we assessed 22 medicinal plants growing naturally on tannery pollutant contaminated (Site-C) and non-contaminated (Site-NC) sites for their ability to accumulate chromium (Cr). The Cr contents in soil and various plant parts were estimated using an atomic absorption spectrophotometer. Translocation and bioconcentration factors were calculated. The soil at Site-C had 27-fold higher concentration of total Cr than at Site-NC. Chromium accumulation is reported for the first time in 50 % of the medicinal plants examined and varied significantly among the sites. Shoots of Ricinus communis and Amaranthus viridis had maximum concentrations of Cr at Site-C, whereas in Site-NC, none of the plants had Cr accumulation >30 ppm. Ricinus communis, Amaranthus viridis, and Amaranthus spinosus had translocation factor (TF) greater than the one in the Site-C and Lantana camara had TF >1 in Site-NC. The bioconcentration factor (BCF) was >1 only for Ricinus communis at both the sites. The majority of the medicinal plants at Site-NC had Cr content exceeding the permissible limit of 2 ppm suggested for herbal raw material. The results of the study clearly emphasize the need for screening plants of therapeutic value for the presence of HMs even when collected from non-contaminated soils. Moreover, proportional allocation of Cr in different plant parts provided an insight on the safety of these parts when specifically used in herbal preparations.

Stage-dependent stoichiometric homeostasis and responses of nutrient resorption in Amaranthus mangostanus to nitrogen and phosphorus addition.

Stoichiometric homeostasis is the ability of plants remaining their element composition relatively stable regardless of changes in nutrient availability, via various physiological mechanisms. Nutrient resorption is one of such key mechanisms, but whether and how nitrogen and phosphorus homeostasis and resorption in plants would change with growth-stages under variable nutrient supply was unclear. A nitrogen (N) and phosphorus (P) fertilizer addition experiment was conducted to evaluate the dynamics of N and P homeostasis and resorption efficiency during different growth-stages of Amaranthus mangostanus in a greenhouse. The homeostasis regulation coefficient of green-leaf P varied significantly, while that of green-leaf N maintained relatively stable across growth stages. Moreover, homeostasis regulation coefficient of N was higher at seedling stage but lower at flowering stage than that of P at corresponding stages, suggesting that the growth of A. mangostanus may switch from being more N- to P-limited from vegetative to reproductive stage. N resorption efficiency (NRE) was higher and P resorption efficiency (PRE) was lower at flowering than seed-filling stage. The nutrient dynamics displayed here suggested contrasting nutrient homeostasis and resorption responses of plants to environmental nutrient availability across growth stages. These findings can improve the understanding of nutrition maintenance mechanism of plants during their growth.

A Novel Tetraenoic Fatty Acid Isolated from Amaranthus spinosus Inhibits Proliferation and Induces Apoptosis of Human Liver Cancer Cells.

Amaranthus spinosus Linn. (Family: Amaranthaceae) has been shown to be useful in preventing and mitigating adverse pathophysiological conditions and complex diseases. However, only limited information is available on the anticancer potential of this plant. In this study, we examined the antiproliferative and pro-apoptotic effects of a novel fatty acid isolated from A. spinosus-(14E,18E,22E,26E)-methyl nonacosa-14,18,22,26 tetraenoate-against HepG2 human liver cancer cells. We used 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to determine cell viability, flow cytometry assay for cell cycle analysis, and Western blot analysis to measure protein expression of Cdc2), cyclin B1, Bcl-2-associated X protein (Bax), and B-cell lymphoma 2 (Bcl-2). The MTT assay showed that the fatty acid markedly inhibited the proliferation of HepG2 cells in a dosage-dependent fashion, with a half maximal inhibitory concentration (IC50) value of 25.52 µmol/L. This antiproliferative result was superior to that of another known fatty acid, linoleic acid (IC50 38.65 µmol/L), but comparable to that of standard anticancer drug doxorubicin (IC50 24.68 µmol/L). The novel fatty acid also induced apoptosis mediated by downregulation of cyclin B1, upregulation of Bax, and downregulation of Bcl-2, resulting in the G2/M transition arrest. Our results provide the first experimental evidence that a novel fatty acid isolated from A. spinosus exhibits significant antiproliferative activity mediated through the induction of apoptosis in HepG2 cells. These encouraging results may facilitate the development of A. spinosus fatty acid for the prevention and intervention of hepatocellular carcinoma.

Enhancement of cadmium uptake by Amaranthus caudatus, an ornamental plant, using tea saponin.

In this study, tea saponin (TS) was extracted from tea camellia seed by microwave-assisted extraction. The potential of TS was compared with ethylenediaminetetracetic acid (EDTA), which is used as a common chemical agent to enhance uptake of cadmium (Cd) by Amaranthus caudatus, an ornamental plant in the natural vegetation of Turkey under pot conditions. The enrichment coefficient (EC) and translocation factor (TF) values were calculated to evaluate the removal efficiency of the TS and EDTA. The results showed that an increase in both TS and EDTA concentration significantly increased Cd uptake by A. caudatus, accumulating Cd in different parts of the plant. Higher EC and TF values obtained from stems, leaves, and inflorescences of A. caudatus showed that this plant might be cultivated and used as a hyperaccumulator in the uptake of Cd from the Cd contaminated soils. Thus, the present technique can efficiently reduce the metal load in the food chain; hence, it could be applied in catchment areas of urban cities where Cd contamination has become an unavoidable factor.

Ectopic expression of amaranth seed storage albumin modulates photoassimilate transport and nutrient acquisition in sweetpotato.

Storage proteins in plants, because of high nutrient value, have been a subject of intensive investigation. These proteins are synthesized de novo in the cytoplasm and transported to the storage organelles where they serve as reservoir of energy and supplement of nitrogen during rapid growth and development. Sweetpotato is the seventh most important food crop worldwide, and has a significant contribution to the source of nutrition, albeit with low protein content. To determine the behaviour of seed storage proteins in non-native system, a seed albumin, AmA1, was overexpressed in sweetpotato with an additional aim of improving nutritional quality of tuber proteins. Introduction of AmA1 imparted an increase in protein and amino acid contents as well as the phytophenols. The proteometabolomics analysis revealed a rebalancing of the proteome, with no significant effects on the global metabolome profile of the transgenic tubers. Additionally, the slower degradation of starch and cellulose in transgenic tubers, led to increased post-harvest durability. Present study provides a new insight into the role of a seed storage protein in the modulation of photoassimilate movement and nutrient acquisition.

Pharmacokinetic study of amaranth extract in healthy humans: A randomized trial.

OBJECTIVE: Nitric oxide (NO) is one of the most important signaling molecules produced within the body. Continuous generation of NO is essential for the integrity of the cardiovascular system. The aim of this study was to assess whether oral intake of a nitrate (NO3-)-rich dietary supplement (amaranth extract) is able to increase NO3- and nitrite (NO2-) levels in blood plasma and saliva of healthy adults. METHODS: In the present study, bioavailability and pharmacokinetics of NO3- and NO2- from amaranth extract (2 g as single dose) was studied in 16 healthy individuals and compared with placebo in a crossover design. The NO3- and NO2- levels in plasma as well as saliva were measured up to 24 h. RESULTS: After administration of amaranth extract, the NO3- levels in plasma as well as saliva were found to be significantly (P < 0.001) higher than in the placebo group. The NO2- level in plasma was slightly higher (P < 0.05) in the amaranth group (test group) compared with that in the placebo group, whereas the saliva NO2- level was significantly high (P < 0.001) in the amaranth extract-treated group than the placebo group. CONCLUSIONS: These results clearly indicate that a single oral dose of amaranth extract is able to increase the NO3- and NO2- levels in the body for at least 8 h. The increase in NO3- and NO2- levels can help to improve the overall performance of people involved in vigorous physical activities or sports.

Synergistic improvement of crop physiological status by combination of cadmium immobilization and micronutrient fertilization.

Wollastonite application in cadmium-contaminated soils can reduce cadmium concentrations in plant, while the side effect is the synchronous immobilization of micronutrients, which reduces micronutrient uptake in plant, inducing micronutrient deficient symptoms. Accordingly, we investigated whether the supplement of Zn and Mn fertilizers after the wollastonite addition could promote the growth and photosynthesis in amaranth (Amaranthus tricolor L.). In this study, plants were cultivated in cadmium-contaminated soil under micronutrient fertilization alone, wollastonite addition, and combination of wollastonite and micronutrient fertilization treatments. Then, plant biomass; photosynthesis parameters; and total Cd, Zn, and Mn concentrations were investigated. Moreover, chemical extractions were performed on soil samples. The results show that application of wollastonite decreased Cd, Zn, and Mn concentrations in plant and availability in soil and it increased the gas exchange ability of plants. But, it reduced the chlorophyll content in leaves and had no positive influence on plant biomass. In comparison, Zn and Mn fertilization after wollastonite application greatly increased plant biomass and photosynthetic ability. It also reduced Cd phytoavailability more efficiently. Therefore, synergistic improvement of physiological status of farmland crop by sequential treatment with first wollastonite for cadmium immobilization, and then micronutrient fertilization to avoid micronutrient deficiency, was demonstrated.

Major peptides from amaranth (Amaranthus cruentus) protein inhibit HMG-CoA reductase activity.

The objective of this study was to identify the major peptides generated by the in vitro hydrolysis of Amaranthus cruentus protein and to verify the effect of these peptides on the activity of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA reductase), a key enzyme in cholesterol biosynthesis. A protein isolate was prepared, and an enzymatic hydrolysis that simulated the in vivo digestion of the protein was performed. After hydrolysis, the peptide mixture was filtered through a 3 kDa membrane. The peptide profile of this mixture was determined by reversed phase high performance chromatography (RP-HPLC), and the peptide identification was performed by LC-ESI MS/MS. Three major peptides under 3 kDa were detected, corresponding to more than 90% of the peptides of similar size produced by enzymatic hydrolysis. The sequences identified were GGV, IVG or LVG and VGVI or VGVL. These peptides had not yet been described for amaranth protein nor are they present in known sequences of amaranth grain protein, except LVG, which can be found in amaranth α­amylase. Their ability to inhibit the activity of HMG-CoA reductase was determined, and we found that the sequences GGV, IVG, and VGVL, significantly inhibited this enzyme, suggesting a possible hypocholesterolemic effect.

Multifunctional amaranth cystatin inhibits endogenous and digestive insect cysteine endopeptidases: A potential tool to prevent proteolysis and for the control of insect pests.

In a previous study, the amaranth cystatin was characterized. This cystatin is believed to provide protection from abiotic stress because its transcription is induced in response to heat, drought, and salinity. It has also been shown that recombinant amaranth cystatin inhibits bromelain, ficin, and cysteine endopeptidases from fungal sources and also inhibits the growth of phytopathogenic fungi. In the present study, evidence is presented regarding the potential function of amaranth cystatin as a regulator of endogenous proteinases and insect digestive proteinases. During amaranth germination and seedling growth, different proteolytic profiles were observed at different pH levels in gelatin-containing SDS-PAGE. Most of the proteolytic enzymes detected at pH 4.5 were mainly inhibited by trans-epoxysuccinyl-leucyl amido(4-guanidino)butane (E-64) and the purified recombinant amaranth cystatin. Furthermore, the recombinant amaranth cystatin was active against insect proteinases. In particular, the E-64-sensitive proteolytic digestive enzymes from Callosobruchus maculatus, Zabrotes subfasciatus, and Acanthoscelides obtectus were inhibited by the amaranth cystatin. Taken together, these results suggest multiple roles for cystatin in amaranth, specifically during germination and seedling growth and in the protection of A. hypochondriacus against insect predation. Amaranth cystatin represents a promising tool for diverse applications in the control of insect pest and for preventing undesirable proteolytic activity.

Burkholderia ambifaria and B. caribensis promote growth and increase yield in grain amaranth (Amaranthus cruentus and A. hypochondriacus) by improving plant nitrogen uptake.

Grain amaranth is an emerging crop that produces seeds having high quality protein with balanced amino-acid content. However, production is restricted by agronomic limitations that result in yields that are lower than those normally produced by cereals. In this work, the use of five different rhizobacteria were explored as a strategy to promote growth and yields in Amaranthus hypochondriacus cv. Nutrisol and A. cruentus cv. Candil, two commercially important grain amaranth cultivars. The plants were grown in a rich substrate, high in organic matter, nitrogen (N), and phosphorus (P) and under greenhouse conditions. Burkholderia ambifaria Mex-5 and B. caribensis XV proved to be the most efficient strains and significantly promoted growth in both grain amaranth species tested. Increased grain yield and harvest index occurred in combination with chemical fertilization when tested in A. cruentus. Growth-promotion and improved yields correlated with increased N content in all tissues examined. Positive effects on growth also occurred in A. cruentus plants grown in a poor soil, even after N and P fertilization. No correlation between non-structural carbohydrate levels in roots of inoculated plants and growth promotion was observed. Conversely, gene expression assays performed at 3-, 5- and 7-weeks after seed inoculation in plants inoculated with B. caribensis XV identified a tissue-specific induction of several genes involved in photosynthesis, sugar- and N- metabolism and transport. It is concluded that strains of Burkholderia effectively promote growth and increase seed yields in grain amaranth. Growth promotion was particularly noticeable in plants grown in an infertile soil but also occurred in a well fertilized rich substrate. The positive effects observed may be attributed to a bio-fertilization effect that led to increased N levels in roots and shoots. The latter effect correlated with the differential induction of several genes involved in carbon and N metabolism and transport.

Leaf-level nitrogen use efficiency: definition and importance.

Nitrogen use efficiency (NUE) has been widely used to study the relationship between nitrogen uptake and dry mass production in the plant. As a subsystem of plant nitrogen use efficiency (NUE), I have defined leaf-level NUE as the surplus production (gross production minus leaf respiration) per unit amount of nitrogen allocated to the leaf, with factorization into leaf nitrogen productivity (NP) and mean residence time of leaf nitrogen (MRT). These concepts were applied to two herbaceous stands: a perennial Solidago altissima stand and an annual Amaranthus patulus stand. S. altissima had more than three times higher leaf NUE than A. patulus due to nearly three times longer MRT of leaf N. In both species, NUE and NP were higher at the leaf level than at the plant level, because most leaf N is involved directly in the photosynthetic activity and because leaf surplus production is higher than the plant net production. MRT was longer at the plant level. The more than twice as long MRT at the plant level as at the leaf level in S. altissima was due to a large contribution of nitrogen storage belowground in the winter in this species. Thus, comparisons between a perennial and an annual system and between plant- and leaf-level NUE with their components revealed the importance of N allocation, storage, recycling, and turnover of organs for leaf photosynthetic production and plant dry mass growth.

Phytoremediation of stable Cs from solutions by Calendula alata, Amaranthus chlorostachys and Chenopodium album.

Uptake rate of (133)Cs, at three different concentrations of CsCl, by Calendula alata, Amaranthus chlorostachys and Chenopodium album plants grown outdoors was studied. These plants grow abundantly in semi-arid regions and their varieties exist in many parts of the world. When exposed to lowest Cs concentration 68 percent Cs was remediated by Chenopodium album.(133)Cs accumulation in shoots of Amaranthus chlorostachys reached its highest value of 2146.2 mg kg(-1) at a (133)Cs supply level of 3.95 mg l(-1) of feed solution. The highest concentration ratio value was 4.89 for Amaranthus chlorostachys, whereas for the other tests it ranged from 0.74 to 3.33. Furthermore uptake of (133)Cs by all three species increased with increasing metal concentrations. The results also indicated that hydroponically grown Calendula alata, Amaranthus chlorostachys and Chenopodium album could be used as potential candidate plants for phytoremediation of solutions contaminated with Cs.