The FLOWERING LOCUS T LIKE 2-1 gene of Chenopodium triggers precocious flowering in Arabidopsis seedlings.

The FLOWERING LOCUS T (FT) gene is the essential integrator of flowering regulatory pathways in angiosperms. The paralogs of the FT gene may perform antagonistic functions, as exemplified by BvFT1, that suppresses flowering in Beta vulgaris, unlike the paralogous activator BvFT2. The roles of FT genes in other amaranths were less investigated. Here, we transformed Arabidopsis thaliana with the FLOWERING LOCUS T like (FTL) genes of Chenopodium ficifolium and found that both CfFTL1 and CfFTL2-1 accelerated flowering, despite having been the homologs of the Beta vulgaris floral promoter and suppressor, respectively. The floral promotive effect of CfFTL2-1 was so strong that it caused lethality when overexpressed under the 35S promoter. CfFTL2-1 placed in an inducible cassette accelerated flowering after induction with methoxyphenozide. The spontaneous induction of CfFTL2-1 led to precocious flowering in some primary transformants even without chemical induction. The CqFT2-1 homolog from Chenopodium quinoa had the same impact on viability and flowering as CfFTL2-1 when transferred to A. thaliana. After the FTL gene duplication in Amaranthaceae, the FTL1 copy maintained the role of floral activator. The second copy FTL2 underwent subsequent duplication and functional diversification, which enabled it to control the onset of flowering in amaranths to adapt to variable environments.

The FLOWERINGLOCUS T like 2­1 gene of Chenopodium ficifolium andChenopodium quinoa acts as a strong activator of flowering in Arabidopsis, triggering flowering at cotyledon stage and causing lethality when overexpressed.

Trans-generational effect of cerium oxide-nanoparticles (nCeO2) on Chenopodium rubrum L. and Sinapis alba L. seeds.

Cerium oxide nanoparticles (nCeO2 ) are interesting nanomaterials due to their redox properties. Their wide application could result in unexpected consequences to environmental safety. Unlike acute toxicity, the trans-generational effects of carbohydrate-coated nCeO2 in the environment are still unknown. The main aim of this study was to investigate the effect of treating maternal plants of Chenopodium rubrum L. (red goosefoot) and Sinapis alba L. (white mustard) with uncoated (CeO2 ) and glucose-, levan-, or pullulan-coated nCeO2 (G-, L-, or P-CeO2 ) during seed germination on morphological and physiological characteristics of produced seeds in two subsequent generations. The plant response was studied by measuring germination percentage (Ger), total protein content (TPC), total phenolic content (TPhC), total antioxidative activity (TAA), and catalase (CAT) activity. Results showed that maternal effects of the different nCeO2 treatments persist to at least the second generation in seeds. Generally, C. rubrum was more sensitive to nCeO2 treatments than S. alba . The coated nCeO2 were more effective than uncoated ones in both plant species; L- and P-CeO2 were the most effective in S. alba , while CeO2 and G-CeO2 had a dominant impact in C. rubrum . Enhanced germination in all tested generations of S. alba seeds recommends nCeO2 for seed priming.

CgMYB1, an R2R3-MYB transcription factor, can alleviate abiotic stress in an annual halophyte Chenopodium glaucum.

MYB transcription factors (TFs) are important regulators of the stress response in plants. In the present study, we characterized the CgMYB1 gene in Chenopodium glaucum, a member of the R2R3-MYB TF family. CgMYB1 was located in the nucleus with an activating domain at the C terminus. The CgMYB1 gene could be induced by salt and cold stress in C. glaucum. Overexpressing CgMYB1 in Arabidopsis significantly enhanced salt and cold tolerance, probably by improving physiological performance and stress-related gene expression. Further analysis suggests that the positive response of CgMYB1 to abiotic stress may partially be attributed to the interaction between CgMYB1 and the CgbHLH001 promoter followed by activation of downstream stress-responsive genes, which mediates stress tolerance. Our findings should contribute to further understanding of the function of R2R3 MYB TF in response to abiotic stress.

The high concentrations of abscisic, jasmonic, and salicylic acids produced under long days do not accelerate flowering in Chenopodium ficifolium 459.

The survival and adaptation of angiosperms depends on the proper timing of flowering. The weedy species Chenopodium ficifolium serves as a useful diploid model for comparing the transition to flowering with the important tetraploid crop Chenopodium quinoa due to the close phylogenetic relationship. The detailed transcriptomic and hormonomic study of the floral induction was performed in the short-day accession C. ficifolium 459. The plants grew more rapidly under long days but flowered later than under short days. The high levels of abscisic, jasmonic, and salicylic acids at long days were accompanied by the elevated expression of the genes responding to oxidative stress. The increased concentrations of stress-related phytohormones neither inhibited the plant growth nor accelerated flowering in C. ficifolium 459 at long photoperiods. Enhanced content of cytokinins and the stimulation of cytokinin and gibberellic acid signaling pathways under short days may indicate the possible participation of these phytohormones in floral initiation. The accumulation of auxin metabolites suggests the presence of a dynamic regulatory network in C. ficifolium 459.

Enhanced antioxidant activity of Chenopodium formosanum Koidz. by lactic acid bacteria: Optimization of fermentation conditions.

In this study, different probiotics commonly used to produce fermented dairy products were inoculated independently for Chenopodium formosanum Koidz. fermentation. The strain with the highest level of antioxidant activity was selected and the fermentation process was further optimized via response surface methodology (RSM). Lactobacillus plantarum BCRC 11697 was chosen because, compared to other lactic acid bacteria, it exhibits increased free radical scavenging ability and can produce more phenolic compounds, DPPH (from 72.6% to 93.2%), and ABTS (from 64.2% to 76.9%). Using RSM, we further optimize the fermentation protocol of BCRC 11697 by adjusting the initial fermentation pH, agitation speed, and temperature to reach the highest level of antioxidant activity (73.5% of DPPH and 93.8% of ABTS). The optimal protocol (pH 5.55, 104 rpm, and 24.4°C) resulted in a significant increase in the amount of phenolic compounds as well as the DPPH and ABTS free radical scavenging ability of BCRC 11697 products. The IC50 of the DPPH and ABTS free radical scavenging ability were 0.33 and 2.35 mg/mL, respectively, and both protease and tannase activity increased after RSM. An increase in lower molecular weight (<24 kDa) protein hydrolysates was also observed. Results indicated that djulis fermented by L. plantarum can be a powerful source of natural antioxidants for preventing free radical-initiated diseases.

Transition from C3 to proto-Kranz to C3-C4 intermediate type in the genus Chenopodium (Chenopodiaceae).

The Chenopodiaceae is one of the families including C4 species among eudicots. In this family, the genus Chenopodium is considered to include only C3 species. However, we report here a transition from C3 photosynthesis to proto-Kranz to C3-C4 intermediate type in Chenopodium. We investigated leaf anatomical and photosynthetic traits of 15 species, of which 8 species showed non-Kranz anatomy and a CO2 compensation point (Γ) typical of C3 plants. However, 5 species showed proto-Kranz anatomy and a C3-like Γ, whereas C. strictum showed leaf anatomy and a Γ typical of C3-C4 intermediates. Chenopodium album accessions examined included both proto-Kranz and C3-C4 intermediate types, depending on locality. Glycine decarboxylase, a key photorespiratory enzyme that is involved in the decarboxylation of glycine, was located predominantly in the mesophyll (M) cells of C3 species, in both M and bundle-sheath (BS) cells in proto-Kranz species, and exclusively in BS cells in C3-C4 intermediate species. The M/BS tissue area ratio, number of chloroplasts and mitochondria per BS cell, distribution of these organelles to the centripetal region of BS cells, the degree of inner positioning (vacuolar side of chloroplasts) of mitochondria in M cells, and the size of BS mitochondria also changed with the change in glycine decarboxylase localization. All Chenopodium species examined were C3-like regarding activities and amounts of C3 and C4 photosynthetic enzymes and δ13C values, suggesting that these species perform photosynthesis without contribution of the C4 cycle. This study demonstrates that Chenopodium is not a C3 genus and is valuable for studying evolution of C3-C4 intermediates.

Fermentation of pseudocereals quinoa, canihua, and amaranth to improve mineral accessibility through degradation of phytate.

BACKGROUND: Pseudocereals are nutrient-rich grains with high mineral content but also phytate content. Phytate is a mineral absorption inhibitor. The study's aim was to evaluate phytate degradation during spontaneous fermentation and during Lactobacillus plantarum 299v® fermentation of quinoa, canihua, and amaranth grains and flours. It also aimed to evaluate the accessibility of iron, zinc, and calcium and to estimate their bioavailability before and after the fermentation of flours with starter culture. Lactic acid, pH, phytate, and mineral content were analyzed during fermentation. RESULTS: Higher phytate degradation was found during the fermentation of flours (64-93%) than during that of grains (12-51%). Results suggest that phytate degradation was mainly due to endogenous phytase activity in different pseudocereals rather than the phytase produced by added microorganisms. The addition of Lactobacillus plantarum 299v® resulted in a higher level of lactic acid (76.8-82.4 g kg-1 DM) during fermentation, and a relatively quicker reduction in pH to 4 than in spontaneous fermentation. Mineral accessibility was increased (1.7-4.6-fold) and phytate : mineral molar ratios were reduced (1.5-4.2-fold) in agreement with phytate degradation (1.8-4.2-fold) in fermented flours. The reduced molar ratios were still above the threshold value for the improved estimated mineral bioavailability of mainly iron. CONCLUSION: Fermentation proved to be effective for degrading phytate in pseudocereal flours, but less so in grains. Fermentation with Lactobacillus plantarum 299v® improved mineral accessibility and estimated bioavailability in flours. © 2019 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Modeling leaf CO2 assimilation and Photosystem II photochemistry from chlorophyll fluorescence and the photochemical reflectance index.

We present a simple model to assess the quantum yield of photochemistry (ΦP ) and CO2 assimilation rate from two parameters that are detectable by remote sensing: chlorophyll (chl) fluorescence and the photochemical reflectance index (PRI). ΦP is expressed as a simple function of the chl fluorescence yield (ΦF ) and nonphotochemical quenching (NPQ): ΦP  = 1-bΦF (1 + NPQ). Because NPQ is known to be related with PRI, ΦP can be remotely assessed from solar-induced fluorescence and the PRI. The CO2 assimilation rate can be assessed from the estimated ΦP value with either the maximum carboxylation rate (Vcmax ), the intercellular CO2 concentration (Ci ), or parameters of the stomatal conductance model. The model was applied to experimental data obtained for Chenopodium album leaves under various environmental conditions and was able to successfully predict ΦF values and the CO2 assimilation rate. The present model will improve the accuracy of assessments of gas exchange rates and primary productivity by remote sensing.

Production of fluorescent antibody-labeling proteins in plants using a viral vector and the application in the detection of Acidovorax citrulli and Bamboo mosaic virus.

Serological methods are relatively convenient and simple for the detection of pathogens for front-line workers. On-site visualization of the test results plays a pivotal role in the process. However, an efficient, universal labeling agent for antibodies is needed for the development of efficient serological detection tools. In this study, a Bamboo mosaic virus (BaMV)-based viral vector was employed to express recombinant proteins, collectively designated GfED, consisting of Staphylococcus aureus Protein A domain ED (SpaED) fused to either the N- or C-terminal of an improved green florescent protein (GFP) with or without the coat protein (CP) of BaMV, efficiently in Chenopodium quinoa. The GfED in crude leaf extracts could specifically attach to IgG molecules of rabbits and mice, effectively labeling IgG with GFP, emitting green light at 506 nm when excited at 450 nm using simple, handheld equipment. To demonstrate the applicability of GfED in serological assays, we have developed a fluorescent dot blot assay for the rapid detection of Acidovorax citrulli (Ac), a bacterial pathogen of cucurbits, and BaMV, a viral pathogen of bamboos. By using the crude extracts of inoculated C. quinoa leaves expressing GfED as an IgG-labeling agent, the pathogens were easily and quickly detected through uncomplicated operations using simple equipment, with results observable by the naked eye. Examination using fluorescent microscopy and transmission electron microscopy revealed that the GfED subunits may assemble into virus-like particles, which were further involved in the formation of aggregates of GfED-antibody-antigen complexes with the potential for fluorescence signal enhancement. The results suggested that plant-expressed GfED may serve as a promising alternative of IgG-labeling agent for current serological assays.

The bHLH transcription factor CgbHLH001 is a potential interaction partner of CDPK in halophyte Chenopodium glaucum.

Plants have evolved different abilities to adapt to the ever-fluctuating environments for sessility. Calcium-dependent protein kinase (CDPK) is believed to play a pivotal role in abiotic stress signaling. So far, study on the specific substrates that CDPK recognized in response to adversity is limited. In the present study, we revealed a potential interaction between CDPK and a bHLH transcription factor under salt stress in Chenopodium glaucum. First, we identified a CgCDPK, which was up-regulated under salt and drought stress; then by Y2H screening, CgCDPK was detected to be involved in interaction with a bHLH TF (named as CgbHLH001), which also positively respond to salt and drought stress. Further computational prediction and experiments including GST-pulldown and BiFC assays revealed that potential interaction existed between CgCDPK and CgbHLH001, and they might interact on the plasma membrane. In addition, CgCDPK-overexpressed transgenic tobacco line could significantly accumulate transcripts of NtbHLH (a homolog of CgbHLH001 in N. tabacum), which provided another evidence of correlation between CgCDPK and CgbHLH001. Our results suggest that CgbHLH001 can interact with CgCDPK in signal transduction pathway in response to abiotic stress, which should provide new evidence for further understanding of the substrate specificity of plant CDPK signaling pathway.

Chenopodium polyploidy inferences from Salt Overly Sensitive 1 (SOS1) data.

PREMISE OF THE STUDY: Single-copy nuclear loci can provide powerful insights into polyploid evolution. Chenopodium (Amaranthaceae) is a globally distributed genus composed of approximately 50-75 species. The genus includes several polyploid species, some of which are considered noxious agricultural weeds, and a few are domesticated crops. Very little research has addressed their evolutionary origin to date. We construct a phylogeny for Chenopodium based on two introns of the single-copy nuclear locus Salt Overly Sensitive 1 (SOS1) to clarify the relationships among the genomes of the allotetraploid and allohexaploid species, and to help identify their genome donors. METHODS: Diploid species were sequenced directly, whereas homeologous sequences of polyploid genomes were first separated by plasmid-mediated cloning. Data were evaluated in maximum likelihood and Bayesian phylogenetic analyses. KEY RESULTS: Homeologous sequences of polyploid species were found in four clades, which we designate as A-D. Two distinct polyploid lineages were identified: one composed of American tetraploid species with A and B class homeologs and a second composed of Eastern Hemisphere hexaploid species with B, C, and D class homeologs. CONCLUSIONS: We infer that the two polyploid lineages arose independently and that each lineage may have originated only once. The American diploid, C. standleyanum, was identified as the closest living diploid relative of the A genome donor for American tetraploids, including domesticated C. quinoa, and is of potential importance for quinoa breeding. The east Asian diploid species, C. bryoniifolium, groups with American diploid species, which suggests a transoceanic dispersal.

Ectopic overexpression of the cell wall invertase gene CIN1 leads to dehydration avoidance in tomato.

Drought stress conditions modify source-sink relations, thereby influencing plant growth, adaptive responses, and consequently crop yield. Invertases are key metabolic enzymes regulating sink activity through the hydrolytic cleavage of sucrose into hexose monomers, thus playing a crucial role in plant growth and development. However, the physiological role of invertases during adaptation to abiotic stress conditions is not yet fully understood. Here it is shown that plant adaptation to drought stress can be markedly improved in tomato (Solanum lycopersicum L.) by overexpression of the cell wall invertase (cwInv) gene CIN1 from Chenopodium rubrum. CIN1 overexpression limited stomatal conductance under normal watering regimes, leading to reduced water consumption during the drought period, while photosynthetic activity was maintained. This caused a strong increase in water use efficiency (up to 50%), markedly improving water stress adaptation through an efficient physiological strategy of dehydration avoidance. Drought stress strongly reduced cwInv activity and induced its proteinaceous inhibitor in the leaves of the wild-type plants. However, the CIN1-overexpressing plants registered 3- to 6-fold higher cwInv activity in all analysed conditions. Surprisingly, the enhanced invertase activity did not result in increased hexose concentrations due to the activation of the metabolic carbohydrate fluxes, as reflected by the maintenance of the activity of key enzymes of primary metabolism and increased levels of sugar-phosphate intermediates under water deprivation. The induced sink metabolism in the leaves explained the maintenance of photosynthetic activity, delayed senescence, and increased source activity under drought stress. Moreover, CIN1 plants also presented a better control of production of reactive oxygen species and sustained membrane protection. Those metabolic changes conferred by CIN1 overexpression were accompanied by increases in the concentrations of the senescence-delaying hormone trans-zeatin and decreases in the senescence-inducing ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) in the leaves. Thus, cwInv critically functions at the integration point of metabolic, hormonal, and stress signals, providing a novel strategy to overcome drought-induced limitations to crop yield, without negatively affecting plant fitness under optimal growth conditions.

Pyrolytic and kinetic analysis of two coastal plant species: Artemisia annua and Chenopodium glaucum.

The large amount of coastal plant species available makes them ideal candidates for energy production. In this study, thermogravimetric analysis was used to evaluate the fuel properties of two coastal plant species, and the distributed activation energy model (DAEM) was employed in kinetic analysis. The major mass loss due to devolatilization started at 154 and 162°C at the heating rate of 10°C min(-1) for Artemisia annua and Chenopodium glaucum, respectively. The results showed that the average activation energies of Artemisia annua and Chenopodium glaucum were 169.69 and 170.48 kJ mol(-1), respectively. Furthermore, the activation energy changed while the conversion rate increased, and the frequency factor k 0 decreased greatly while the activation energy decreased. The results also indicated that the devolatilization of the two coastal plant species underwent a set of first-order reactions and could be expressed by the DAEM. Additionally, a simplified mathematical model was proposed to facilitate the prediction of devolatilization curves.

Management of Chenopodium polyspermum toxicity with plasma exchange and hemodialysis.

A 45-year-old male patient was admitted to our emergency department complaining of fatigue, headache, mild confusion, nausea, and vomiting. He had had Type 2 diabetes mellitus for 10 years that was managed with insulin injections. Two days before the onset of symptoms, he had consumed the natural herb Chenopodium polyspermum to regulate his blood glucose levels. Upon examination, he was found to be experiencing tenderness in the upper left abdominal area, icteric sclera, and pallor conjunctivas. Laboratory tests revealed that he was anemic and had increased levels of indirect bilirubin, lactic dehydrogenase, and creatinine in blood. Direct and indirect Coombs tests were negative, and fragmented erythrocytes were observed in peripheral blood smears. The best supportive care was provided, and therapeutic plasma exchange (TPE) treatments were administered. TPE was performed five times and hemolytic findings improved. The patient then developed chronic renal failure and was transferred to the dialysis program and discharged. In this article, we present a case with hemolytic and renal toxicity induced by the ingestion of Chenopodium polyspermum that was managed with TPE and hemodialysis.

Multivariate analyses of salt stress and metabolite sensing in auto- and heterotroph Chenopodium cell suspensions.

Global warming increases plant salt stress via evaporation after irrigation, but how plant cells sense salt stress remains unknown. Here, we searched for correlation-based targets of salt stress sensing in Chenopodium rubrum cell suspension cultures. We proposed a linkage between the sensing of salt stress and the sensing of distinct metabolites. Consequently, we analysed various extracellular pH signals in autotroph and heterotroph cell suspensions. Our search included signals after 52 treatments: salt and osmotic stress, ion channel inhibitors (amiloride, quinidine), salt-sensing modulators (proline), amino acids, carboxylic acids and regulators (salicylic acid, 2,4-dichlorphenoxyacetic acid). Multivariate analyses revealed hirarchical clusters of signals and five principal components of extracellular proton flux. The principal component correlated with salt stress was an antagonism of γ-aminobutyric and salicylic acid, confirming involvement of acid-sensing ion channels (ASICs) in salt stress sensing. Proline, short non-substituted mono-carboxylic acids (C2-C6), lactic acid and amiloride characterised the four uncorrelated principal components of proton flux. The proline-associated principal component included an antagonism of 2,4-dichlorphenoxyacetic acid and a set of amino acids (hydrophobic, polar, acidic, basic). The five principal components captured 100% of variance of extracellular proton flux. Thus, a bias-free, functional high-throughput screening was established to extract new clusters of response elements and potential signalling pathways, and to serve as a core for quantitative meta-analysis in plant biology. The eigenvectors reorient research, associating proline with development instead of salt stress, and the proof of existence of multiple components of proton flux can help to resolve controversy about the acid growth theory.

Stoichiometric homeostasis of vascular plants in the Inner Mongolia grassland.

Stoichiometric homeostasis, the degree to which an organism maintains its C:N:P ratios around a given species- or stage-specific value despite variation in the relative availabilities of elements in its resource supplies, is a key parameter in ecological stoichiometry. However, its regulation and role in affecting organismal and ecosystem processes is still poorly understood in vascular plants. We performed a sand culture experiment and a field nitrogen (N) and phosphorus (P) addition experiment to evaluate the strength of N, P and N:P homeostasis in higher plants in the Inner Mongolia grassland. Our results showed that homeostatic regulation coefficients (H) of vascular plants ranged from 1.93 to 14.5. H varied according to plant species, aboveground and belowground compartments, plant developmental stage, and overall plant nutrient content and N:P ratio. H for belowground and for foliage were inversely related, while H increased with plant developmental stage. H for N (H(N)) was consistently greater than H for P (H(P)) while H for N:P (H(N:P)) was consistently greater than H(N) and H(P). Furthermore, species with greater N and P contents and lower N:P were less homeostatic, suggesting that more homeostatic plants are more conservative nutrient users. The results demonstrate that H of plants encompasses a considerable range but is stronger than that of algae and fungi and weaker than that of animals. This is the first comprehensive evaluation of factors influencing stoichiometric homeostasis in vascular plants.

Effect of the heavy metals on the developmental stages of ovule and seed proteins in Chenopodium botrys L. (Chenopodiaceae).

Excessive amounts of heavy metals adversely affect plant growth and development. Also, the presence of elevated levels of heavy metal ions triggers a wide range of cellular responses including changes in gene expression and synthesis of metal-detoxifying peptides. The overall objective of this research was to elucidate some microscopic effects of heavy metals on the formation, development, and structure of ovule and seed storage proteins in Chenopodium botrys L. To achieve this purpose, the surrounding area of Hame-Kasi iron and copper mine (Hamedan, Iran) was chosen as a polluted area where the amount of some heavy metals was several times higher than the natural soils. Flowers and young pods were removed from nonpolluted and polluted plants, fixed in FAA 70 and subjected to developmental studies. Our results showed that heavy metals can cause some abnormalities during the ovule developmental process. Decreasing the size of embryo sac, quick growth of inner integument, quick degradation of embryonic sac cells, accumulation of dark particles, irregularity, and even blockage of the nuclear envelope formation and increasing of embryonic sac cytoplasm concentration were the effects of heavy metals. Reduction of ovule number was also seen in the plants collected from polluted area. For protein studies, mature seeds were harvested from nonpolluted and polluted plants at the same time. Seed storage proteins (water soluble ones) were extracted and studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after being prepared. The results revealed that there were no significant differences between seed protein bands of polluted and nonpolluted samples, but the quantity of protein bands was different, and there was a slight quantitative increase of bands with molecular mass of 35 and 15 kD and decrease of a band with molecular mass of 17 kD in the plants collected from the mine area.

Ammonium thiosulphate enhanced phytoextraction from mercury contaminated soil--results from a greenhouse study.

According to the 'hard and soft' acid-base principle, mercury is a 'soft metal' and will preferentially form soluble chemical complexes with sulphur-containing ligands. In this work mercury uptake by Chenopodium glaucum L. growing on mercury-contaminated soil was promoted using ammonium thiosulphate. The relative geochemical fractionation of mercury in the soil was subsequently investigated as a function of plant growth with and without thiosulphate amendment. The results indicate that the solubility of mercury is significantly increased through the application of thiosulphate to the soil. Substantially higher mercury levels were found in C. glaucum L. treated with 2 g kg(-1) thiosulphate of soil when compared to the non-treated plants. Compared with initial soil, soluble and exchangeable fractions were increased both in planted and planted treated plants. However, no significant difference was observed between the soils of the planted and planted treated plants. The oxide-bound mercury concentration was significantly decreased for the planted soil (treated and non-treated) at the end of the experiment. Moreover, this fraction was highly correlated with the plant tissue mercury concentration. Taken together, thiosulphate assisted phytoextraction could be used to reduce environmental risk apparent for mercury-contaminated soil through reducing the oxide bound fractions, while managing the bioavailable fractions (compared with no treated plant).

Cell-specific association of heat shock-induced proton flux with actin ring formation in Chenopodium cells: comparison of auto- and heterotroph cultures.

A comparison of the responses of extracellular pH, buffering capacity and actin cytoskeleton in autotroph and heterotroph Chenopodium rubrum cells to heat shock revealed cell-specific reactions: alkalinization caused by the heat shock at 25-35 degrees C was higher in heterotroph cells and characterized by heat shock-induced changes in the actin cytoskeleton and ring formation at 35-37 degrees C. Rings (diameter up to 3 mum) disappeared and extracellular pH recovered after the heat-shocked cells were transferred into control medium. At 41 degrees C, no rings but a network of coarse actin filaments were induced; at higher temperatures, fragmentation of the actin cytoskeleton and release of buffering compounds occurred, indicating sudden membrane leakage at 45-47 degrees C. The calcium chelator EGTA [ethylene-glycol-bis(beta-aminoethyl-ether)-N,N,N',N'-tetraacetic-acid] increased the frequency of heat shock-induced rings. Ionophore (10 microM nigericin) and the sodium/proton antiport blocker [100 microM 5-(N-ethyl-N-isopropyl)-amiloride] mimicked the effect of the 37 degrees C heat shock. The cytoskeleton inhibitors latrunculin B, cytochalasin D and 2,3-butanedione monoxime inhibited ring formation but not alkalinization. In autotroph cells, the treatment with nigericin (10 microM) produced rings, although the actin cytoskeleton was not affected by temperatures up to 45 degrees C. We conclude that Chenopodium cells express a specific temperature sensor that has ascendancy over the organization of the actin cytoskeleton; this is probably a temperature- and potential-sensitive proton-transporting mechanism that is dependent on the culture conditions of the heterotroph cells.

Two flowering locus T (FT) homologs in Chenopodium rubrum differ in expression patterns.

FLOWERING LOCUS T (FT) like genes are crucial regulators (both positive and negative) of flowering in angiosperms. We identified two FT homologs in Chenopodium rubrum, a short-day species used as a model plant for the studies of photoperiodic flower induction. We found that CrFTL1 gene was highly inducible by a 12-h dark period, which in turn induced flowering. On the other hand, photoperiodic treatments that did not induce flowering (short dark periods, or a permissive darkness interrupted by a night break) caused only a slight increase in CrFTL1 mRNA level. We demonstrated diurnal oscillation of CrFTL1 expression with peaks in the middle of a light period. The oscillation persisted under constant darkness. Unlike FT homologs in rice and Pharbitis, the CrFTL1 expression under constant darkness was very low. The CrFTL2 gene showed constitutive expression. We suggest that the CrFTL1 gene may play a role as a floral regulator, but the function of CrFTL2 remains unknown.