RESUMO
Grain amaranth (Amaranthus spp.) is an emerging crop rich in proteins and other valuable nutrients. It was domesticated twice, in Mexico and Peru. Although global trade is dominated by Mexican species of amaranth, Peruvian amaranth (A. caudatus, kiwicha) has remained neglected, although it harbours valuable traits. In the current study, we investigate the accumulation of polyunsaturated fatty acids, comparing four genotypes of A. caudatus with K432, a commercial variety deriving from the Mexican species A. hypochondriacus under the temperate environment of Southwest Germany. We show that the A. caudatus genotypes flowered later (only in late autumn), such that they were taller as compared to the Mexican hybrid but yielded fewer grains. The oil of kiwicha showed a significantly higher content of unsaturated fatty acids, especially of linoleic acid and α-linolenic acid compared to early flowering genotype K432. To gain insight into the molecular mechanisms behind these differences, we sequenced the genomes of the A. hypochondriacus × hybridus variety K432 and the Peruvian kiwicha genotype 8300 and identified the homologues for genes involved in the ω3 fatty-acid pathway and concurrent oxylipin metabolism, as well as of key factors for jasmonate signalling and cold acclimation. We followed the expression of these transcripts over three stages of seed development in all five genotypes. We find that transcripts for Δ6 desaturases are elevated in kiwicha, whereas in the Mexican hybrid, the concurrent lipoxygenase is more active, which is followed by the activation of jasmonate biosynthesis and signalling. The early accumulation of transcripts involved in cold-stress signalling reports that the Mexican hybrid experiences cold stress already early in autumn, whereas the kiwicha genotypes do not display indications for cold stress, except for the very final phase, when there were already freezing temperatures. We interpret the higher content of unsaturated fatty acids in the context of the different climatic conditions shaping domestication (tropical conditions in the case of Mexican amaranth, sharp cold snaps in the case of kiwicha) and suggest that kiwicha oil has high potential as functional food which can be developed further by tailoring genetic backgrounds, agricultural practice, and processing.
Assuntos
Amaranthus , Ácido Linoleico , Ácido Linoleico/metabolismo , Peru , Amaranthus/genética , Ácidos Graxos Insaturados/metabolismoRESUMO
BACKGROUND: In soybean fields containing insecticide- and herbicide-resistant genetically engineered varieties, some weed species have increasingly become difficult to manage and may favor the population growth of secondary pests like Spodoptera cosmioides (Walker) (Lepidoptera: Noctuidae). To test this hypothesis, we measured life-history traits, population growth parameters and adult nutrient content of S. cosmioides reared on foliage from four Amaranthus species, from Cry1Ac Bt and non-Bt soybean varieties, and on meridic artificial diet. RESULTS: Larvae reared on A. palmeri and A. spinosus had a shorter development time (5-7 days) than larvae raised on the soybean varieties and A. hybridus. Armyworm survival probability was zero on A. viridis and highest (80% and 71%) on soybeans and A. palmeri. The latter and the artificial diet produced the heaviest larvae and pupae, in contrast to the non-Bt soybean variety. Body nutrient content diverged mostly for adults reared on artificial diet compared with those raised on the soybean varieties. The intrinsic rate of population increase (overall fitness) was 27.88% higher for the armyworms on A. palmeri, Cry1Ac Bt soybean and artificial diet compared with those on non-Bt soybean, A. spinosus and A. hybridus. CONCLUSIONS: Cry1Ac soybean fields infested by some Amaranthus weeds, especially A. palmeri, are conducive to the population growth of S. cosmioides. Integrated pest management programs may be needed to properly manage S. cosmioides in soybean fields, with surveillance for population peaks and judicious control measures when needed. © 2022 Society of Chemical Industry.
Assuntos
Amaranthus , Fabaceae , Mariposas , Amaranthus/genética , Animais , Proteínas de Bactérias/genética , Endotoxinas , Proteínas Hemolisinas/genética , Larva/genética , Mariposas/genética , Plantas Daninhas , Plantas Geneticamente Modificadas/genética , Glycine max/genética , Spodoptera/genéticaRESUMO
BACKGROUND: Amaranthus palmeri S. Watson, a problematic weed infesting summer crops in Argentina, has developed multiple herbicide resistance. Resistance to acetolactate synthase (ALS)-inhibiting herbicides is particularly common, with high-level resistance mostly caused by different mutations in the ALS enzyme. Six versions of the enzyme were identified from a resistant A. palmeri population, carrying substitutions D376E, A205V, A122S, A282D, W574L and S653N. This work aims to provide a comparative analysis of these mutants and the wild-type (WT) enzyme to fully understand the herbicide resistance. Thus, all the versions of the ALS gene from A. palmeri were heterologously expressed and purified to evaluate their kinetics and inhibitory response against imazethapyr, diclosulam, chlorimuron-ethyl, flucarbazone-sodium and bispyribac-sodium. RESULTS: A decrease in catalytic efficiency was detected in the A205V, A122S-A282D, W574L and S653N ApALS enzymes, whereas only A205V and W574L substitutions also produced a decrease in the substrate affinity. In vitro ALS inhibition assays confirmed cross-resistance to almost all the herbicides tested, with the exception of A282D ApALS, which was as susceptible as WT ApALS. Moreover, the results confirmed that the novel substitution A122S provides cross-resistance to at least one herbicide within each of the five families of ALS inhibitors, and this property could be explained by a lower number of hydrophobic interactions between the herbicides and the mutant enzyme. CONCLUSION: This is the first report to compare various mutations in vitro from A. palmeri ALS. Our data contribute to understanding the impacts of herbicide resistance in this species. © 2021 Society of Chemical Industry.
Assuntos
Acetolactato Sintase , Amaranthus , Herbicidas , Acetolactato Sintase/genética , Amaranthus/genética , Resistência a Herbicidas/genética , Herbicidas/farmacologia , Mutação de Sentido Incorreto , Proteínas de Plantas/genéticaRESUMO
The introduction of glyphosate-resistant (GR) crops revolutionized weed management; however, the improper use of this technology has selected for a wide range of weeds resistant to glyphosate, referred to as superweeds. We characterized the high glyphosate resistance level of an Amaranthus hybridus population (GRH)-a superweed collected in a GR-soybean field from Cordoba, Argentina-as well as the resistance mechanisms that govern it in comparison to a susceptible population (GSH). The GRH population was 100.6 times more resistant than the GSH population. Reduced absorption and metabolism of glyphosate, as well as gene duplication of 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) or its overexpression did not contribute to this resistance. However, GSH plants translocated at least 10% more 14C-glyphosate to the rest of the plant and roots than GRH plants at 9 h after treatment. In addition, a novel triple amino acid substitution from TAP (wild type, GSH) to IVS (triple mutant, GRH) was identified in the EPSPS gene of the GRH. The nucleotide substitutions consisted of ATA102, GTC103 and TCA106 instead of ACA102, GCG103, and CCA106, respectively. The hydrogen bond distances between Gly-101 and Arg-105 positions increased from 2.89 Å (wild type) to 2.93 Å (triple-mutant) according to the EPSPS structural modeling. These results support that the high level of glyphosate resistance of the GRH A. hybridus population was mainly governed by the triple mutation TAP-IVS found of the EPSPS target site, but the impaired translocation of herbicide also contributed in this resistance.
Assuntos
3-Fosfoshikimato 1-Carboxiviniltransferase/genética , Amaranthus/efeitos dos fármacos , Amaranthus/genética , Substituição de Aminoácidos , Glicina/análogos & derivados , Resistência a Herbicidas/genética , Herbicidas/farmacologia , Argentina , Relação Dose-Resposta a Droga , Duplicação Gênica , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Glicina/metabolismo , Glicina/farmacologia , Mutação/efeitos dos fármacos , Fosfatos/metabolismo , Proteínas de Plantas/metabolismo , Raízes de Plantas/metabolismo , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/genética , Alinhamento de Sequência , Análise de Sequência de Proteína , Ácido Chiquímico/metabolismo , Glycine max , GlifosatoRESUMO
BACKGROUND: The evolution of herbicide-resistant weeds is one of the most important concerns of global agriculture. Amaranthus hybridus L. is a competitive weed for summer crops in South America. In this article, we intend to unravel the molecular mechanisms by which an A. hybridus population from Argentina has become resistant to extraordinarily high levels of glyphosate. RESULTS: The glyphosate-resistant population (A) exhibited particularly high parameters of resistance (GR50 = 20 900 g ai ha-1 , Rf = 314), with all plants completing a normal life cycle even after 32X dose application. No shikimic acid accumulation was detected in the resistant plants at any of the glyphosate concentrations tested. Molecular and genetic analyses revealed a novel triple substitution (TAP-IVS: T102I, A103V, and P106S) in the 5-enol-pyruvylshikimate-3-phosphate synthase (EPSPS) enzyme of population A and an incipient increase on the epsps relative copy number but without effects on the epsps transcription levels. The novel mechanism was prevalent, with 48% and 52% of the individuals being homozygous and heterozygous for the triple substitution, respectively. In silico conformational studies revealed that TAP-IVS triple substitution would generate an EPSPS with a functional active site but with an increased restriction to glyphosate binding. CONCLUSION: The prevalence of the TAP-IVS triple substitution as the sole mechanism detected in the highly glyphosate resistant population suggests the evolution of a new glyphosate resistance mechanism arising in A. hybridus. This is the first report of a naturally occurring EPSPS triple substitution and the first glyphosate target-site resistance mechanism described in A. hybridus. © 2018 Society of Chemical Industry.
Assuntos
3-Fosfoshikimato 1-Carboxiviniltransferase/genética , Amaranthus/efeitos dos fármacos , Amaranthus/genética , Substituição de Aminoácidos , Glicina/análogos & derivados , Resistência a Herbicidas/genética , 3-Fosfoshikimato 1-Carboxiviniltransferase/química , Amaranthus/enzimologia , Sequência de Aminoácidos , Argentina , Sequência de Bases , Relação Dose-Resposta a Droga , Glicina/farmacologia , Mutação , GlifosatoRESUMO
The insertion of peptides is a biotechnology tool widely used to improve the nutraceutical properties of proteins. Because the effect of these insertions in protein stability and function is difficult to predict, it should be determined experimentally. In this study, we created two variants of amarantin acidic subunit and analyzed them along with other four proteins reported previously. We measured their response against two destabilizing agents: temperature and urea. The six proteins presented the insertion of antihypertensive peptides (VYVYVYVY or RIPP) in the variable regions of the protein. We observed that their effect strongly depended on the site of the insertion. The insertion in the variable region I stabilized the protein both thermally and chemically, but it affected the inhibitory activity of the angiotensin-converting enzyme in vitro. In contrast, insertions in other three regions were severely destabilizing, producing molten globules. Our findings reveal that the insertion of bioactive peptides in variable regions of a protein can increase or decrease the protein's thermal and chemical stability and that these conformational changes may also alter its final activity.
Assuntos
Amaranthus/genética , Anti-Hipertensivos/metabolismo , Peptídeos/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Engenharia de Proteínas/métodos , Estabilidade Proteica , Temperatura , UreiaRESUMO
BACKGROUND: Herbicide-resistant weeds are a serious problem worldwide. Recently, two populations of Amaranthus palmeri with suspected cross-resistance to acetolactate synthase (ALS)-inhibiting herbicides (R1 and R2) were found by farmers in two locations in Argentina (Vicuña Mackenna and Totoras, respectively). We conducted studies to confirm and elucidate the mechanism of resistance. RESULTS: We performed in vivo dose-response assays, and confirmed that both populations had strong resistance to chlorimuron-ethyl, diclosulam and imazethapyr when compared with a susceptible population (S). In vitro ALS activity inhibition tests only indicated considerable resistance to imazethapyr and chlorimuron-ethyl, indicating that other non-target mechanisms could be involved in diclosulam resistance. Subsequently, molecular analysis of als nucleotide sequences revealed three single base-pair mutations producing substitutions in amino acids previously associated with resistance to ALS inhibitors, A122, W574, and S653. CONCLUSION: This is the first report of als resistance alleles in A. palmeri in Argentina. The data support the involvement of a target-site mechanism of resistance to ALS-inhibiting herbicides. © 2017 Society of Chemical Industry.
Assuntos
Acetolactato Sintase/antagonistas & inibidores , Amaranthus/efeitos dos fármacos , Amaranthus/enzimologia , Inibidores Enzimáticos/farmacologia , Herbicidas/farmacologia , Proteínas de Plantas/antagonistas & inibidores , Acetolactato Sintase/genética , Acetolactato Sintase/metabolismo , Amaranthus/genética , Argentina , Resistência a Herbicidas , Ácidos Nicotínicos/farmacologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Pirimidinas/farmacologia , Compostos de Sulfonilureia/farmacologiaRESUMO
Following the introduction of glyphosate-resistant (GR)-cotton crops in Mexico, farmers have relied upon glyphosate as being the only herbicide for in-season weed control. Continuous use of glyphosate within the same year and over multiple successive years has resulted in the selection of glyphosate resistance in Palmer amaranth (Amarantus palmeri). Dose-response assays confirmed resistance in seven different accessions. The resistance ratio based on GR50 values (50% growth reduction) varied between 12 and 83. At 1000 µM glyphosate, shikimic acid accumulation in the S-accession was 30- to 2-fold higher at compared to R-accessions. At 96 h after treatment, 35-44% and 61% of applied 14C-glyphosate was taken up by leaves of plants from R- and S-accessions, respectively. At this time, a significantly higher proportion of the glyphosate absorbed remained in the treated leaf of R-plants (55-69%) compared to S-plants (36%). Glyphosate metabolism was low and did not differ between resistant and susceptible plants. Glyphosate was differentially metabolized to AMPA and glyoxylate in plants of R- and S-accessions, although it was low in both accessions (<10%). There were differences in 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) enzyme activity by 50% (I50) between R- and S-accessions. However, no significant differences were found in the basal EPSPS activity (µmol inorganic phosphate µg-1 total soluble protein min-1) between R- and S-accessions. A point mutation Pro-106-Ser was evidenced in three accessions. The results confirmed the resistance of Palmer amaranth accessions to glyphosate collected from GR-cotton crops from Mexico. This is the first study demonstrating glyphosate-resistance in Palmer amaranth from Mexico.
Assuntos
Amaranthus/efeitos dos fármacos , Glicina/análogos & derivados , Herbicidas/farmacologia , Amaranthus/genética , Amaranthus/metabolismo , Glicina/farmacologia , Resistência a Herbicidas , Mutação , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Daninhas/genética , Ácido Chiquímico , GlifosatoRESUMO
The domestication syndrome comprises phenotypic changes that differentiate crops from their wild ancestors. We compared the genomic variation and phenotypic differentiation of the two putative domestication traits seed size and seed colour of the grain amaranth Amaranthus caudatus, which is an ancient crop of South America, and its two close wild relatives and putative ancestors A. hybridus and A. quitensis. Genotyping 119 accessions of the three species from the Andean region using genotyping by sequencing (GBS) resulted in 9485 SNPs that revealed a strong genetic differentiation of cultivated A. caudatus from its two relatives. A. quitensis and A. hybridus accessions did not cluster by their species assignment but formed mixed groups according to their geographic origin in Ecuador and Peru, respectively. A. caudatus had a higher genetic diversity than its close relatives and shared a high proportion of polymorphisms with their wild relatives consistent with the absence of a strong bottleneck or a high level of recent gene flow. Genome sizes and seed sizes were not significantly different between A. caudatus and its relatives, although a genetically distinct group of A. caudatus from Bolivia had significantly larger seeds. We conclude that despite a long history of human cultivation and selection for white grain colour, A. caudatus shows a weak genomic and phenotypic domestication syndrome and proposes that it is an incompletely domesticated crop species either because of weak selection or high levels of gene flow from its sympatric close undomesticated relatives that counteracted the fixation of key domestication traits.
Assuntos
Amaranthus/genética , Domesticação , Bolívia , Equador , Fluxo Gênico , Genótipo , Humanos , Peru , FenótipoRESUMO
The snack foods market is currently demanding healthier products. A ready-to-eat expanded snack with high nutritional and antioxidant value was developed from a mixture (70:30) of whole amarantin transgenic maize (Zea mays L.) and black common bean (Phaseolus vulgaris L.) by optimizing the extrusion process. Extruder operation conditions were: feed moisture content (FMC, 15-25 %, wet basis), barrel temperature (BT, 120-170 °C), and screw speed (SS, 50-240). The desirability numeric method of the response surface methodology (RSM) was applied as the optimization technique over four response variables [expansion ratio (ER), bulk density (BD), hardness (H), antioxidant activity (AoxA)] to obtain maximum ER and AoxA, and minimum BD, and H values. The best combination of extrusion process variables for producing an optimized expanded snack (OES, healthy snack) were: FMC = 15 %/BT = 157 °C/SS = 238 rpm. The OES had ER = 2.86, BD = 0.119 g/cm (3) , H = 1.818 N, and AoxA = 13,681 µmol Trolox equivalent (TE)/100 g, dry weight. The extrusion conditions used to produce the OES increased the AoxA (ORAC: +18 %, ABTS:+20 %) respect to the unprocessed whole grains mixture. A 50 g portion of OES had higher protein content (7.23 vs 2.32 g), total dietary fiber (7.50 vs 1.97 g), total phenolic content (122 vs 47 mg GAE), and AoxA (6626 vs 763 µmol TE), and lower energy (169 vs 264 kcal) than an expanded commercial snack (ECS = Cheetos™). Because of its high content of quality protein, dietary fiber and phenolics, as well as high AoxA and low energy density, the OES could be used for health promotion and chronic disease prevention and as an alternative to the widely available commercial snacks with high caloric content and low nutritional/nutraceutical value.
Assuntos
Amaranthus/genética , Antioxidantes/metabolismo , Phaseolus/química , Fenóis/metabolismo , Lanches , Zea mays/química , Amaranthus/química , Antioxidantes/análise , Fibras na Dieta/análise , Fibras na Dieta/metabolismo , Proteínas Alimentares/análise , Proteínas Alimentares/metabolismo , Farinha/análise , Manipulação de Alimentos , Valor Nutritivo , Phaseolus/genética , Fenóis/análise , Proteínas de Plantas/análise , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Sementes/química , Sementes/genética , Temperatura , Grãos Integrais , Zea mays/genéticaRESUMO
Nuclear factor-Y (NF-Y), is a plant heterotrimeric transcription factor constituted by NF-YA, NF-YB and NF-YC subunits. The function of many NF-Y subunits, mostly of the A and B type, has been studied in plants, but knowledge regarding the C subunit remains fragmentary. Here, a water stress-induced NF-YC gene from Amaranthus hypochondriacus (AhNF-YC) was further characterized by its overexpression in transgenic Arabidospis thaliana plants. A role in development was inferred from modified growth rates in root, rosettes and inflorescences recorded in AhNF-YC overexpressing Arabidopsis plants, in addition to a delayed onset of flowering. Also, the overexpression of AhNF-YC caused increased seedling sensitivity to abscisic acid (ABA), and influenced the expression of several genes involved in secondary metabolism, development and ABA-related responses. An altered expression of the latter in water stressed and recovered transgenic plants, together with the observed increase in ABA sensitivity, suggested that their increased water stress resistance was partly ABA-dependent. An untargeted metabolomic analysis also revealed an altered metabolite pattern, both in normal and water stress/recovery conditions. These results suggest that AhNF-YC may play an important regulatory role in both development and stress, and represents a candidate gene for the engineering of abiotic stress resistance in commercial crops.
Assuntos
Amaranthus/genética , Arabidopsis/fisiologia , Fator de Ligação a CCAAT/genética , Expressão Ectópica do Gene , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Estresse Fisiológico/genética , Amaranthus/metabolismo , Sequência de Aminoácidos , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Fator de Ligação a CCAAT/química , Fator de Ligação a CCAAT/metabolismo , Secas , Análise de Sequência com Séries de Oligonucleotídeos , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Alinhamento de Sequência , Análise de Sequência de DNARESUMO
In this research it was attempted to overexpress the acidic subunit, from the 11S amaranth seed globulin termed amarantin, modified with antihypertensive peptides in Escherichia coli Rosetta (DE3) by manipulating some factors in batch fermenter such as growth medium composition, inducer (isopropyl ß-D-thiogalactopyranoside [IPTG] or lactose), air flow, cultivation temperature, agitation speed and induction time. The possibility of using several minimal media and lactose as inducer to increase yields of the recombinant protein was investigated. Previous fermentations at flask level showed that two minimal culture media (A6 and A7) and 0.5% (w/v) lactose presented high yields of the engineered protein expression. Thus, the latter two media were tested at fermenter level, the lactose inducer, and different environmental conditions. Factors with significant effects were identified by Plackett-Burman design with center points and were adjusted at the level suggested and the yields of the recombinant protein were increased from 303.2 to 1,531 mg L(-1) in A6 and from 363.4 to 1,681 mg L(-1) in A7. Unlike some patents where the highest productivity was achieved at 24 h or afterwards, in this research the best productivity of the recombinant acidic subunit was attained at 4 and 6 h of induction using both media, respectively.
Assuntos
Amaranthus/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Globulinas/biossíntese , Lactose/metabolismo , Proteínas de Plantas/biossíntese , Reatores Biológicos , Biotecnologia/métodos , Fermentação , Globulinas/química , Globulinas/genética , Patentes como Assunto , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismoRESUMO
The major staple food crops production is not able to fulfill food requirement of the global population due to relatively higher population growth rate in developing countries. The research on these crops for exploring their ultimate yield potential is currently at a plateau level. To replace the existing pressure on these major crops there is an urgent need to explore other alternative crops having the potential to replace and fulfill the available food demand. FAO statistics reveal that there is a high frequency of low birth weight children in the developing countries, which is primarily due to deficiency of micronutrients in the mother's diet. Amaranth, an underutilized crop and a cheap source of proteins, minerals, vitamin A and C, seems to be a future crop which can substantiate this demand due to its tremendous yield potential and nutritional qualities, also recently gained worldwide attention. Recently, current interest in amaranth also resides in the fact that it has a great amount of genetic diversity, phenotypic plasticity, and is extremely adaptable to adverse growing conditions, resists heat and drought, has no major disease problem, and is among the easiest of plants to grow in agriculturally marginal lands. The present review is an effort to gather the available knowledge on various diversified fields of sciences for the future exploitation of the crop.
Assuntos
Amaranthus , Suplementos Nutricionais , Amaranthus/química , Amaranthus/genética , Amaranthus/crescimento & desenvolvimento , Cruzamento , Produtos Agrícolas/química , Produtos Agrícolas/crescimento & desenvolvimento , Produtos Agrícolas/história , Fibras na Dieta , Suplementos Nutricionais/análise , Abastecimento de Alimentos , Fósseis , Variação Genética , Grécia , História do Século XVI , História do Século XVIII , História do Século XIX , História do Século XX , História do Século XXI , História Antiga , Humanos , Medicina Tradicional , México , Micronutrientes/análise , Valor Nutritivo , Óleos de Plantas/análise , Proteínas de Plantas/análise , Plantas Medicinais , Sementes/químicaRESUMO
Bioactive compounds present in foods could potentially have beneficial effects on human health. In this study we report the in vitro inhibitory capacity of peptides released from amaranth seed proteins after enzymatic digestion, against dipeptidyl peptidase IV (DPPIV); an enzyme known to deactivate incretins, hormones involved in insulin secretion. Other seeds, such as soybean, black bean, and wheat were also tested. The highest inhibition of DPPIV was observed with amaranth peptides released after simulated gastrointestinal digestion, showing an IC(50) of 1.1mg/mL in a dose-dependent manner. In silico tryptic digestion of amaranth globulins was carried out releasing peptides larger than 13 residues. Some of these peptides were used for the in silico prediction of their binding modes with DPPIV. Docking models showed that the possible mechanism of globulin peptides to inhibit DPPIV was through blocking the active dimer formation. Peptides were also found inside the major cavity where the natural substrates reach the catalytic site of the enzyme. This is the first report of the identification of inhibitory DPPIV peptides from amaranth hydrolysates and the prediction of their binding modes at the molecular level, leading to their possible use as functional food ingredients in the prevention of diabetes.
Assuntos
Amaranthus/química , Inibidores da Dipeptidil Peptidase IV/química , Peptídeos/química , Proteínas de Plantas/química , Amaranthus/genética , Sequência de Aminoácidos , Animais , Domínio Catalítico , Digestão , Dipeptidil Peptidase 4/química , Inibidores da Dipeptidil Peptidase IV/isolamento & purificação , Humanos , Hidrólise , Modelos Biológicos , Dados de Sequência Molecular , Peptídeos/genética , Peptídeos/isolamento & purificação , Proteínas de Plantas/genética , Sementes/química , SuínosRESUMO
Amaranth seeds are considered as an excellent complementary source of food protein due to their balanced amino acid composition. Amarantin acidic subunit has the potential as a functional and nutraceutical protein, and it is structurally a good candidate for modification. The aim of this work was to improve its functionality, then the primary structure was modified into the third variable region of 11S globulins, by inserting antihypertensive peptides: four Val-Tyr in tandem and Arg-Ile-Pro-Pro in the C-terminal region. Modified protein was expressed in Escherichia coli Origami (DE3) and was purified. The culture conditions, including the culture media, temperature, agitation speed and air flow were tested in order to obtain an increased expression levels of the modified protein. A 2(3) factorial design was used for evaluate the effect of environmental conditions on modified protein production. The results indicated that the yield of modified protein could be increased by up 3-fold in bioreactor as compared with flask. In addition, the temperature, the agitation speed and the oxygen were significant factors on the expression of the antihypertensive protein. The maximum production was 99 mg protein-L(-1). The hydrolyzed protein showed a high inhibitory activity of the angiotensin converting enzyme (IC50=0.047 mg mL(-1)).
Assuntos
Inibidores da Enzima Conversora de Angiotensina/isolamento & purificação , Escherichia coli/genética , Proteínas de Plantas/isolamento & purificação , Proteínas Recombinantes/genética , Amaranthus/genética , Reatores Biológicos , Regulação da Expressão Gênica de Plantas , Peptídeos/química , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas Recombinantes/isolamento & purificação , Sementes/genéticaRESUMO
BACKGROUND: Amaranth 7S globulin is a minor globulin component and its impact on the properties of an amaranth protein ingredient depends on its proportion in the variety of amaranth being considered. Some physicochemical, functional and angiotesin I-converting enzyme (ACE) inhibitory properties of amaranth vicilin were studied in this work and compared with the 11S globulin. RESULTS: Fluorescence spectroscopy results indicated that 7S globulin tryptophans were more exposed to the solvent and, by calorimetry, the 7S globulin denaturation temperature (T(d) ) was found lower than the 11S globulin T(d) , suggesting a more flexible structure. The 7S globulin surface hydrophobicity was higher than that of the 11S globulin, which is in agreement with the better emulsifying properties of the 7S globulin. The solubility in neutral buffer of the 7S globulin (851 ± 25 g kg(-1) ) was also higher than that of the 11S globulin (195 ± 6 g kg(-1) ). Bioinformatic analyses showed the presence of ACE inhibitory peptides encrypted in 7S tryptic sequences and peptides released after in vitro gastrointestinal digestion showed a high ACE-inhibitory capacity (IC(50) = 0.17 g L(-1) ), similar to that of 11S globulin peptides. CONCLUSION: Compared with the 11S globulin, the 7S globulin presents similar ACE inhibitory activity and some functional advantages, better solubility and emulsifying activity, which suits some food requirements. The functional behavior has been related with the structural properties.
Assuntos
Amaranthus/metabolismo , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Globulinas/farmacologia , Proteínas de Plantas/farmacologia , Amaranthus/química , Amaranthus/genética , Inibidores da Enzima Conversora de Angiotensina/química , Regulação da Expressão Gênica de Plantas/fisiologia , Globulinas/genética , Globulinas/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Espectrometria de FluorescênciaRESUMO
Calcium (Ca(2+)) is a critical ion for the growth and development of plants and plays an important role in signal transduction pathways in response to biotic and abiotic stresses. We investigated the Ca(2+) stress responsive-genes in amaranth leaves by using the suppression subtractive hybridization technique. Screening of the libraries generated 420 up-regulated transcripts and 199 down-regulated transcripts. The differentially expressed transcripts were associated with general stress response, transcription factors, gene regulation, signal transduction, and some other with unknown function. Selected genes were used to study their differential regulation by sqRT-PCR. Among the up-regulated transcripts, a fragment containing the motif of C3HC4-type RING-Zinc family was further characterized. The ORF of amaranth zinc finger protein (AhZnf) has a closer relationship with its ortholog from Ricinus communis while is distantly related to the Arabidopsis thaliana C3HC4-type ortholog. We have identified a novel putative zinc finger protein along with other novel proteins such as the wall associated kinase, phosphoinositide binding protein, and rhomboid protease involved in response to Ca(2+) stress in amaranth leaves.
Assuntos
Amaranthus/genética , Cálcio/farmacologia , Hibridização de Ácido Nucleico/métodos , Proteínas de Plantas/genética , Estresse Fisiológico/efeitos dos fármacos , Amaranthus/efeitos dos fármacos , Amaranthus/crescimento & desenvolvimento , Amaranthus/fisiologia , Sequência de Aminoácidos , Sequência de Bases , Regulação para Baixo/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Biblioteca Gênica , Genes de Plantas/genética , Dados de Sequência Molecular , Filogenia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , RNA Mensageiro/genética , RNA de Plantas/genética , Plântula/efeitos dos fármacos , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/fisiologia , Alinhamento de Sequência , Análise de Sequência de DNA , Transdução de Sinais , Fatores de Transcrição/genética , Ativação Transcricional/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos , Dedos de Zinco/genéticaRESUMO
*Amaranthus tuberculatus represents one of the most dramatic cases of weed invasion documented in the midwestern USA. The species is infamous for evolving resistance to multiple herbicides, and predicting whether these resistances may be transferred to widespread weeds of the Amaranthus hybridus aggregate is a matter of epidemiological concern. Here, we explore the patterns of genetic exchange between Amaranthus tuberculatus and A. hybridus in an effort to understand whether allele introgression occurs throughout the genome and if fecundity penalties are associated with genetic exchange. *We evaluated 192 homoploid BC(1)s at 197 amplified fragment length polymorphism (AFLP) loci, as well as two loci associated with herbicide resistance: ALS and PPO. We also assessed the fecundity of each genotype by evaluation of seed production or pollen development. *It was discovered that genetic exchange between the species is unidirectional. Whereas A. hybridus alleles transfer with little or no penalty to A. tuberculatus, the reciprocal exchange is significantly distorted and potentially of limited evolutionary consequence. *Our previous hypothesis suggesting unidirectional introgression at ALS owing to circumstantial linkage is now modified to account for the more generalized distortion of genetic exchange observed in this study.
Assuntos
Amaranthus/genética , Transferência Genética Horizontal , Genes de Plantas , Resistência a Herbicidas/genética , Hibridização Genética , Polimorfismo Genético , Agricultura , Alelos , Genoma de Planta , Pólen , Reprodução , Sementes , Estados UnidosRESUMO
Amaranth seeds are rich in protein with a high nutritional value, but little is known about their bioactive compounds that could benefit health. The objectives of this research were to investigate the presence, characterization, and the anticarcinogenic properties of the peptide lunasin in amaranth seeds. Furthermore, to predict and identify other peptides in amaranth seed with potential biological activities. ELISA showed an average concentration of 11.1 microg lunasin equivalent/g total extracted protein in four genotypes of mature amaranth seeds. Glutelin fraction had the highest lunasin concentration (3.0 microg/g). Lunasin was also identified in albumin, prolamin and globulin amaranth protein fractions and even in popped amaranth seeds. Western blot analysis revealed a band at 18.5 kDa, and MALDI-TOF analysis showed that this peptide matched more than 60% of the soybean lunasin peptide sequence. Glutelin extracts digested with trypsin, showed the induction of apoptosis against HeLa cells. Prediction of other bioactive peptides in amaranth globulins and glutelins were mainly antihypertensive. This is the first study that reports the presence of a lunasin-like peptide and other potentially bioactive peptides in amaranth protein fractions.
Assuntos
Amaranthus/química , Glutens/química , Proteínas de Plantas/isolamento & purificação , Sementes , Amaranthus/genética , Anticarcinógenos , Anti-Hipertensivos , Apoptose , Ensaio de Imunoadsorção Enzimática/métodos , Genótipo , Células HeLa , Humanos , Peso Molecular , Valor Nutritivo , Mapeamento de Peptídeos , Proteínas de Plantas/química , Sementes/química , Especificidade da EspécieRESUMO
A cDNA, encoding a cysteine protease inhibitor (AhCPI), was isolated from an immature seed cDNA library of grain amaranth (Amaranthus hypochondriacus L.) and characterized. It encoded a polypeptide of 247 amino acids (aa), including a putative N-terminal signal peptide. Other relevant regions found in its sequence included the G and PW conserved aa motifs, the consensus LARFAV sequence for phytocystatins and the reactive site QVVAG. The predicted aa sequence for AhCPI showed a significant homology to other plant cystatins. Gene expression analyses indicated that AhCPI was constitutively expressed in mature seeds, and gradually decreased during germination. In vegetative tissues, AhCPI was expressed in the radicle and hypocotyls of seedlings and in the stems and roots of young plantlets. Its expression in roots and stems increased substantially in response to water deficit, salinity-, cold- and heat-stress, whereas heat-stress induced a rapid and transient accumulation of AhCPI transcripts in leaves. The results obtained were suggestive of multiple roles for AhCPI in grain amaranth, acting as a regulator of seed germination and as a protective agent against diverse types of abiotic stress, which induced this gene in a tissue- and stress-specific manner. The work herewith described reports a novel, and apparently, single cystatin protein in which, in agreement with other plant model systems, could have a regulatory role in germination, and further expands previous findings linking the accumulation of protease inhibitors, mostly of the serine proteinase type, with protection against (a)biotic stress in A. hypochondriacus.