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1.
Ecotoxicol Environ Saf ; 211: 111942, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33476850

RESUMO

In this work, the internalization and distribution of citric acid-coated magnetite nanoparticles (here, Fe3O4-NPs) in soybean and alfalfa tissues and their effects on plant growth were studied. Both legumes were germinated in pots containing an inert growing matrix (vermiculite) to which Hoagland solution without (control, C), with Fe3O4-NPs (50 and 100 mgironL-1, NP50 and NP100), or with the same amount of soluble iron supplied as Fe-EDTA (Fe50, Fe100) was added once before sowing. Then, plants were watered with the standard nutrient solution. The observation of superparamagnetic signals in root tissues at harvest (26 days after emergence) indicated Fe3O4-NPs uptake by both legumes. A weak superparamagnetic signal was also present in the stems and leaves of alfalfa plants. These findings suggest that Fe3O4-NPs are readily absorbed but not translocated (soybean) or scarcely translocated (alfalfa) from the roots to the shoots. The addition of both iron sources resulted in increased root weight; however, only the addition of Fe3O4-NPs resulted in significantly higher root surface; shoot weight also increased significantly. As a general trend, chlorophyll content enhanced in plants grown in vermiculite supplemented with extra iron at pre-sowing; the greatest increase was observed with NP50. The only antioxidant enzyme significantly affected by our treatments was catalase, whose activity increased in the roots and shoots of both species exposed to Fe3O4-NPs. However, no symptoms of oxidative stress, such as increased lipid peroxidation or reactive oxygen species accumulation, were evidenced in any of these legumes. Besides, no evidence of cell membrane damage or cell death was found. Our results suggest that citric acid-coated Fe3O4-NPs are not toxic to soybean and alfalfa; instead, they behave as plant growth stimulators.


Assuntos
Ácido Cítrico/química , Nanopartículas de Magnetita/química , Medicago sativa/crescimento & desenvolvimento , Soja/crescimento & desenvolvimento , Clorofila/metabolismo , Ácido Cítrico/metabolismo , Germinação , Ferro/metabolismo , Nanopartículas de Magnetita/toxicidade , Medicago sativa/metabolismo , Nanopartículas/metabolismo , Desenvolvimento Vegetal , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Soja/metabolismo
2.
Chemosphere ; 262: 128361, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182109

RESUMO

Although Cd is threatening to the environment, animal, and human, the eco-friendly approach to mitigate the Cd-toxicity in alfalfa was barely studied. Therefore, this study aims at elucidating the role of S, a crucial macroelement, in alleviating Cd toxicity in alfalfa plants. The supplementation of S in Cd-stressed alfalfa reversed the detrimental effect on plant biomass, chlorophyll synthesis, and protein concentration. Interestingly, S surplus restored the photosynthetic kinetics, such as Fv/Fm, Pi_ABS, and Mo values in leaves of Cd-stressed alfalfa. Further, Cd-induced adverse effect on membrane stability, cell viability, and redox status was restored due to S under Cd stress. The exogenous S not only increased S status and the expression of sulfate transporters (MsSULRT1;2 and MsSULTR1;3), but also decreased the Cd concentration in the shoot by retaining elevated Cd in root tissue. Further analysis revealed the upregulation of MsGS (glutathione synthetase) and MsPCS1 (phytochelatin synthase) genes along with the increased concentration of glutathione and phytochelatin, predominantly in roots subjected to S surplus under Cd stress. The subcellular Cd analysis showed elevated Cd in the cell wall but not in the vacuole. It suggests that S-induced elevated glutathione enables the phytochelatin to bind with excess Cd leading to subcellular sequestration in the cell wall of roots. Also, S stimulates the S-metabolites and GR enzyme that coordinately counteracts Cd-induced oxidative damage. These findings can be utilized to popularize the application of S and to perform breeding/transgenic experiments to develop Cd-free forage crops.


Assuntos
Cádmio/toxicidade , Glutationa/metabolismo , Medicago sativa/fisiologia , Fitoquelatinas/metabolismo , Poluentes do Solo/toxicidade , Enxofre/toxicidade , Aminoaciltransferases , Cádmio/metabolismo , Parede Celular/metabolismo , Medicago sativa/metabolismo , Oxirredução , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Poluentes do Solo/metabolismo , Enxofre/metabolismo
3.
Food Chem ; 340: 128147, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33032148

RESUMO

Alfalfa sprouts are well known for their nutritive values. Although there are several studies reported the positive impact of elevated CO2 (eCO2) on plants, there are no in-depth, comprehensive studies on how eCO2 could improve the sprouting of plant seeds. Herein, the production of health-promoting metabolites was determined in eCO2 (620 ppm)-treated Alfalfa sprout cultivars (Giza 1, Nubaria and Ismailia 1). eCO2 increased the photosynthetic process and pigment contents, which consequently induced carbohydrates, proteins, fats and fiber accumulation. eCO2 also boosted the levels of vitamins, phenolics, flavonoids and mineral individuals and enhanced the antioxidant capacity of alfalfa sprouts. Interestingly, eCO2 reduced the antinutritional factor l-canavanine content in Ismailia 1 cultivar and improved the anti-inflammatory activities through inhibiting cyclooxygenase-2 and lipoxygenase activity. Therefore, eCO2 is a promising approach to improve the health-promoting prospective of alfalfa sprouts to be a valuable source of nutritious and bioactive compounds in our daily diet.


Assuntos
Dióxido de Carbono/metabolismo , Medicago sativa/metabolismo , Nutrientes/análise , Antioxidantes/química , Catalase/metabolismo , Cromatografia Líquida de Alta Pressão , Análise por Conglomerados , Flavonoides/análise , Cromatografia Gasosa-Espectrometria de Massas , Genótipo , Medicago sativa/genética , Peroxidases/metabolismo , Fenóis/análise , Fotossíntese , Proteínas de Plantas/metabolismo , Sementes/química , Sementes/crescimento & desenvolvimento , Sementes/metabolismo
4.
Ecotoxicol Environ Saf ; 202: 111011, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800236

RESUMO

Boron (B) deficiency and surplus are the main factors that affect plant growth and yield. A better understanding of the response mechanisms of plant reproductive organs to stress induced by B deficiency and surplus could provide new insights to potential strategies for improving seed yield and quality. In this study, we aimed to elucidate the mechanisms of tolerance to B-induced stress in the reproductive organs of alfalfa (Medicago sativa L. cv. 'Aohan'). We initially used five B concentrations (0 mg B L-1, 400 mg B L-1, 800 mg B L-1, 1200 mg B L-1, and 1600 mg B L-1) to determine the B deficient, sufficient, and surplus levels in the field. Secondly, we examined changes in metabolite profiles of alfalfa 'Aohan' reproductive organs in response to B deficiency (0 mg B L-1), B sufficiency (800 mg B L-1), and B surplus (1600 mg B L-1) conditions using gas chromatography-mass spectrometry (GC-MS). Flowers and seeds from alfalfa 'Aohan' showed different metabolite profiles and resistance capacity under B deficiency and surplus conditions. B deficiency led to the excessive accumulation of sugars and phenolic compounds in alfalfa 'Aohan' and seeds, respectively, thus causing abscission or the abortion of reproductive organs. In contrast, B surplus severely reduced the levels of metabolites associated with amino acid and carbohydrate metabolism, resulting in the flowers falling and, therefore, low seed yield. Overall, B deficiency predominantly reduced seed yield and quality of alfalfa 'Aohan', while B surplus mainly affected seed yield of alfalfa 'Aohan'.


Assuntos
Boro/deficiência , Boro/toxicidade , Células Germinativas Vegetais/efeitos dos fármacos , Medicago sativa/crescimento & desenvolvimento , Sementes/efeitos dos fármacos , Poluentes do Solo/toxicidade , Aminoácidos/metabolismo , Metabolismo dos Carboidratos/efeitos dos fármacos , Cromatografia Gasosa-Espectrometria de Massas , Células Germinativas Vegetais/metabolismo , Medicago sativa/metabolismo , Metabolômica , Sementes/metabolismo , Poluentes do Solo/metabolismo
5.
Appl Environ Microbiol ; 86(15)2020 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-32471917

RESUMO

Plant roots shape the rhizosphere community by secreting compounds that recruit diverse bacteria. Colonization of various plant roots by the motile alphaproteobacterium Azospirillum brasilens e causes increased plant growth, root volume, and crop yield. Bacterial chemotaxis in this and other motile soil bacteria is critical for competitive colonization of the root surfaces. The role of chemotaxis in root surface colonization has previously been established by endpoint analyses of bacterial colonization levels detected a few hours to days after inoculation. More recently, microfluidic devices have been used to study plant-microbe interactions, but these devices are size limited. Here, we use a novel slide-in chamber that allows real-time monitoring of plant-microbe interactions using agriculturally relevant seedlings to characterize how bacterial chemotaxis mediates plant root surface colonization during the association of A. brasilens e with Triticum aestivum (wheat) and Medicago sativa (alfalfa) seedlings. We track A. brasilense accumulation in the rhizosphere and on the root surfaces of wheat and alfalfa. A. brasilense motile cells display distinct chemotaxis behaviors in different regions of the roots, including attractant and repellent responses that ultimately drive surface colonization patterns. We also combine these observations with real-time analyses of behaviors of wild-type and mutant strains to link chemotaxis responses to distinct chemicals identified in root exudates to specific chemoreceptors that together explain the chemotactic response of motile cells in different regions of the roots. Furthermore, the bacterial second messenger c-di-GMP modulates these chemotaxis responses. Together, these findings illustrate dynamic bacterial chemotaxis responses to rhizosphere gradients that guide root surface colonization.IMPORTANCE Plant root exudates play critical roles in shaping rhizosphere microbial communities, and the ability of motile bacteria to respond to these gradients mediates competitive colonization of root surfaces. Root exudates are complex chemical mixtures that are spatially and temporally dynamic. Identifying the exact chemical(s) that mediates the recruitment of soil bacteria to specific regions of the roots is thus challenging. Here, we connect patterns of bacterial chemotaxis responses and sensing by chemoreceptors to chemicals found in root exudate gradients and identify key chemical signals that shape root surface colonization in different plants and regions of the roots.


Assuntos
Azospirillum brasilense/fisiologia , Medicago sativa/metabolismo , Raízes de Plantas/metabolismo , Rizosfera , Plântula/metabolismo , Triticum/metabolismo , Quimiotaxia , Medicago sativa/microbiologia , Plântula/microbiologia , Triticum/microbiologia
6.
J Dairy Sci ; 103(7): 6087-6099, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32389470

RESUMO

Our objective was to determine the effects of replacing alfalfa silage (AS) neutral detergent fiber (NDF) with corn silage (CS) NDF at 2 levels of forage NDF (FNDF) on enteric methane (CH4), lactation performance, ruminal fluid characteristics, digestibility, and metabolism of N and energy in Holstein and Jersey cows. Twelve Holstein and 12 Jersey cows (all primiparous and mid-lactation) were used in a triplicated split-plot 4 × 4 Latin square experiment, where breed and diet formed the main and subplots, respectively. The 4 iso-nitrogenous and iso-starch dietary treatments were arranged as a 2 × 2 factorial with 2 levels of FNDF [19 (low FNDF, LF) and 24% (high FNDF, HF) of dry matter] and 2 sources of FNDF (70:30 and 30:70 ratio of AS NDF to CS NDF). Soyhull (non-forage NDF) and corn grain were respectively used to keep dietary NDF and starch content similar across diets. Total collection of feces and urine over 3 d was performed on 8 cows (1 Latin square from each breed). The difference in dry matter intake (DMI) between Holsteins and Jerseys was greater when fed AS than CS. Compared with Jerseys, Holstein cows had greater body weight (48%), DMI (34%), fat- and protein-corrected milk (FPCM; 31%) and CH4 production (22%; 471 vs. 385 g/d). However, breed did not affect CH4 intensity (g/kg of FPCM) or yield (g/kg of DMI), nutrient digestibility, and N partitioning. Compared with HF, LF-fed cows had greater DMI (10%), N intake (8%), and FPCM (5%), but they were 5% less efficient (both FPCM/DMI and milk N/intake N). Compared with HF, LF-fed cows excreted 11 and 17% less urinary N (g/d and % of N intake, respectively). In spite of lower (2.5%) acetate and higher (10%) propionate (mol/100 mol ruminal volatile fatty acids) LF-fed cows had greater (6%) CH4 production (g/d) than did HF-fed cows, most likely due to increased DMI, as affected mainly by the soyhulls. Compared with AS, CS-fed cows had greater DMI (7%) and FPCM (4%), but they were less efficient (5%), and CH4 yield (g/kg of DMI) was reduced by 8%. In addition, per unit of gross energy intake, CS-fed cows lost less urinary energy (15%) and CH energy (11%) than did AS-fed cows. We concluded that, in contrast to level and source of FNDF, breed did not affect digestive and metabolic efficiencies, and, furthermore, neither breed nor dietary treatments affected CH4 intensity. The tradeoff between CH4 and N losses may have implications in future studies assessing the environmental effects of milk production when approached from a whole-farm perspective.


Assuntos
Fibras na Dieta/administração & dosagem , Digestão/efeitos dos fármacos , Lactação/efeitos dos fármacos , Metano/biossíntese , Nitrogênio/metabolismo , Silagem/análise , Animais , Bovinos , Estudos Cross-Over , Dieta/veterinária , Fibras na Dieta/metabolismo , Metabolismo Energético , Ácidos Graxos Voláteis/metabolismo , Fezes/química , Feminino , Medicago sativa/metabolismo , Leite/química , Proteínas do Leite/análise , Rúmen/metabolismo , Amido/metabolismo , Zea mays/metabolismo
7.
Chemosphere ; 254: 126724, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32334248

RESUMO

Chelants application can increase the bioavailability of metals, subsequently limiting plant growth and reducing the efficiency of phytoremediation. Plant growth-promoting rhizobacteria (PGPRs) and rhizobium have substantial potential to improve plant growth and plant tolerance to metal stress. We evaluated the effects of co-inoculation with a PGPR strain (Paenibacillus mucilaginosus) and a Cu-resistant rhizobium strain (Sinorhizobium meliloti) on the efficiency of biodegradable chelant (S,S-ethylenediaminedisuccinic acid; EDDS) assisted phytoremediation of a Cu contaminated soil using alfalfa. The highest total Cu extraction by alfalfa was observed in the EDDS-treated soil upon co-inoculation with the PGPR and rhizobium strains, which was 1.2 times higher than that without co-inoculation. Partial least squares path modeling identified plant oxidative damage and soil microbial biomass as the key variables influencing Cu uptake by alfalfa roots. Co-inoculation significantly reduced the oxidative damage to alfalfa by mitigating the accumulation of malondialdehyde and reactive oxygen species, and improving the antioxidation capacity of the plant in the presence of EDDS. EDDS application decreased microbial diversity in the rhizosphere, whereas co-inoculation increased microbial biomass carbon and nitrogen, and microbial community diversity. Increased relative abundances of Actinobacteria and Bacillus and the presence of Firmicutes taxa as potential biomarkers demonstrated that co-inoculation increased soil nutrient content, and improved plant growth. Co-inoculation with PGPR and rhizobium can be useful for altering plant-soil biochemical responses during EDDS-enhanced phytoremediation to alleviate phytotoxicity of heavy metals and improve soil biochemical activities. This study provides an effective strategy for improving phytoremediation efficiency and soil quality during chelant assisted phytoremediation of metal-contaminated soils.


Assuntos
Inoculantes Agrícolas , Biodegradação Ambiental/efeitos dos fármacos , Cobre/metabolismo , Etilenodiaminas/farmacologia , Rizosfera , Poluentes do Solo/metabolismo , Succinatos/farmacologia , Biomassa , Medicago sativa/metabolismo , Microbiota , Desenvolvimento Vegetal , Raízes de Plantas/microbiologia , Rhizobium
8.
Ecotoxicol Environ Saf ; 196: 110537, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32272346

RESUMO

The objective of the study was to explore the influences of arbuscular mycorrhizae (AM), phosphorus (P) fertiliser, biochar application (BC) and their interactions on Medicago sativa growth, nutrient, Cd content and AM fungi-plant symbioses. Applications of both P fertiliser and BC significantly increased total biomass and P and potassium (K) uptake, regardless of AM. When no P fertiliser or BC was used, the shoot biomass and nitrogen (N), P, and K contents in the +AM treatments were 1.39, 1.54, 4.53 and 2.06 times higher than those in the -AM treatments, respectively. AM fungi only elevated the total P uptake by 44.03% when P fertiliser was applied at a rate of 30 mg P kg-1 in the absence of BC addition. With BC application or high-P fertiliser input (100 mg P kg-1), the soil available P was significantly higher than that in the other treatments, and AM fungi significantly reduced the shoot biomass. The minimum Cd concentration occurred in the shoots of alfalfas treated with BC and high-P fertiliser inputs; this concentration was lower than the maximum permitted concentration in China. Although the BC and high-P inputs could eliminate the positive mycorrhizal response, the results suggested that BC application in combination with high-P fertiliser input could not only increase forage yields but also lower Cd concentrations to meet the forage safety standards by the dilution effect.


Assuntos
Cádmio/metabolismo , Carvão Vegetal/farmacologia , Medicago sativa/crescimento & desenvolvimento , Micorrizas/fisiologia , Fósforo/farmacologia , Biomassa , Carvão Vegetal/análise , Fertilizantes/análise , Medicago sativa/efeitos dos fármacos , Medicago sativa/metabolismo , Medicago sativa/microbiologia , Nutrientes/metabolismo , Fósforo/análise , Fósforo/metabolismo , Poluentes do Solo/metabolismo , Simbiose/efeitos dos fármacos
9.
Plant Physiol Biochem ; 151: 323-333, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32251957

RESUMO

Soil salinity of fields is often non-uniform. To obtain a better understanding of molecular response to non-uniform salt stress, we conducted transcriptomic analysis on the leaves and roots of alfalfa grown under 0/0, 200/200, and 0/200 mM NaCl treatments. A total of 233,742 unigenes were obtained from the assembled cDNA libraries. There were 98 and 710 unigenes identified as significantly differentially expressed genes (DEGs) in the leaves of non-uniform and uniform salt treatment, respectively. Furthermore, there were 5178 DEGs in the roots under uniform salt stress, 273 DEGs in the non-saline side and 4616 in the high-saline side roots under non-uniform salt stress. Alfalfa treated with non-uniform salinity had greater dry weight and less salt damage compared to treatment with uniform salinity. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the DEGs in roots revealed that both sides of the non-uniform salinity were enriched in pathways related to "phenylpropanoid biosynthesis" and "linoleic acid metabolism"; and "MAPK signaling pathway-plant" was also indicated as a key pathway in the high-saline roots. We also combined a set of important salt-response genes and found that roots from the non-saline side developed more roots with increased water uptake by altering the expression of aquaporins and genes related to growth regulation. Moreover, the hormone signal transduction and the antioxidant pathway probably play important roles in inducing more salt-related genes and increasing resistance to non-uniform salt stress on both sides of the roots.


Assuntos
Medicago sativa , Tolerância ao Sal , Transcriptoma , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Medicago sativa/genética , Medicago sativa/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Salinidade , Estresse Salino/genética , Tolerância ao Sal/genética
10.
J Appl Microbiol ; 129(3): 665-679, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32215998

RESUMO

AIMS: This study was designed to evaluate the biocontrol of the arbuscular mycorrhizal fungus (AMF) Funnelliformis mosseae and the rhizobium Sinorhizobium medicae on alfalfa (Medicago sativa) wilt caused by Fusarium oxysporum, a severe soil-borne fungal pathogen. METHODS AND RESULTS: The effects of co-inoculation of F. mosseae and S. medicae on alfalfa growth, nitrogen, phosphorus uptake and wilt caused by F. oxysporum were tested. Plant defence-related chemicals were measured to reveal the biochemical mechanism by which alfalfa responds to pathogen infection and how it is regulated by AMF and rhizobium. Pathogen infection caused typical yellowing of alfalfa leaflets and significantly reduced plant AMF colonization. AMF or rhizobium alone and the co-inoculation reduced the plant disease index by 83·2, 48·4 and 81·8% respectively. Inoculation with AMF or rhizobium alone increased the dry weight of alfalfa by more than 13 and 3 times respectively; it also increased plant chlorophyll content by 65·6 and 16·6% respectively. Co-inoculation of AMF and rhizobium induced the plant to accumulate more disease-related antioxidant enzymes, plant hydrolase and plant hormones, such as superoxide dismutase, ß-1,3-glucanase, chitinase, and phenylalanine ammonialyase, abscisic acid, ethylene and H2 O2 , under pathogen stress. CONCLUSIONS: Co-inoculation with F. mosseae and S. medicae offered complementarily improved alfalfa nutrient uptake and growth, which increased plant health. The co-inoculation of AMF and rhizobium regulated plant physiological and biochemical processes and induced plants to produce defence-related compounds, thus decreasing the severity of disease. The simultaneous application of F. mosseae and S. medicae is a potential biocontrol strategy to increase the systemic defence responses of alfalfa to Fusarium wilt. SIGNIFICANCE AND IMPACT OF THE STUDY: This research showed that complex plant-pathogen interactions are affected by rhizobium and AMF, providing insight into plant-microbiome interactions in the rhizosphere as well as the application of the microbiome in agriculture production.


Assuntos
Fusarium/patogenicidade , Medicago sativa/microbiologia , Micorrizas/fisiologia , Doenças das Plantas/prevenção & controle , Sinorhizobium/fisiologia , Medicago sativa/crescimento & desenvolvimento , Medicago sativa/metabolismo , Nutrientes/metabolismo , Controle Biológico de Vetores , Doenças das Plantas/microbiologia , Rizosfera , Microbiologia do Solo
11.
Int J Mol Sci ; 21(3)2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32019165

RESUMO

Alfalfa is the most extensively cultivated forage legume worldwide, and salinity constitutes the main environmental scourge limiting its growth and productivity. To unravel the potential molecular mechanism involved in salt tolerance in alfalfa, we accomplished a combined analysis of parallel reaction monitoring-based proteomic technique and targeted metabolism. Based on proteomic analysis, salt stress induced 226 differentially abundant proteins (DAPs). Among them, 118 DAPs related to the antioxidant system, including glutathione metabolism and oxidation-reduction pathways, were significantly up-regulated. Data are available via ProteomeXchange with identifier PXD017166. Overall, 107 determined metabolites revealed that the tricarboxylic acid (TCA) cycle, especially the malate to oxaloacetate conversion step, was strongly stimulated by salt stress. This leads to an up-regulation by about 5 times the ratio of NADPH/NADP+, as well as about 3 to 5 times in the antioxidant enzymes activities, including those of catalase and peroxidase and proline contents. However, the expression levels of DAPs related to the Calvin-Benson-Bassham (CBB) cycle and photorespiration pathway were dramatically inhibited following salt treatment. Consistently, metabolic analysis showed that the metabolite amounts related to carbon assimilation and photorespiration decreased by about 40% after exposure to 200 mM NaCl for 14 d, leading ultimately to a reduction in net photosynthesis by around 30%. Our findings highlighted also the importance of the supplied extra reducing power, thanks to the TCA cycle, in the well-functioning of glutathione to remove and scavenge the reactive oxygen species (ROS) and mitigate subsequently the oxidative deleterious effect of salt on carbon metabolism including the CBB cycle.


Assuntos
Antioxidantes/farmacologia , Medicago sativa/efeitos dos fármacos , Metaboloma/efeitos dos fármacos , Fotossíntese , Proteínas de Plantas/metabolismo , Proteoma/análise , Estresse Salino , Medicago sativa/crescimento & desenvolvimento , Medicago sativa/metabolismo , Espécies Reativas de Oxigênio/metabolismo
12.
Oxid Med Cell Longev ; 2020: 8569237, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32104541

RESUMO

The flavonoids were extracted from alfalfa using ethanol assisted with ultrasonic extraction and purified by D101 macroporous resin column chromatography. The chemical composition and content of ethanol elution fractions (EEFs) were assessed by ultrahigh-performance liquid chromatography and hybrid quadrupole time of flight mass spectrometry (UHPLC-Q-TOF-MS) and aluminum nitrate-sodium nitrite-sodium hydroxide colorimetric method. The in vitro antioxidant activity of two EEFs was conducted by scavenging DPPH free radical, and the main antioxidants of 75% EEFs were screened using DPPH-UHPLC. Moreover, the in vivo antioxidant activity of 75% EEFs and the growth performance of broilers were studied. The results showed that the content of 30% and 75% EEFs was 26.20% and 62.57%. Fifteen compounds were identified from 75% EEFs, and five of them were reported in alfalfa for the first time. The scavenging activity of 75% and 30% EEFs (200 µg/mL) against DPPH was 95.51% and 78.85%. The peak area of 5,3',4'-trihydroxyflavone and hyperoside was decreased by 82.69% and 76.04%, which exhibited strong scavenging capacities. The total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and glutathione peroxidase (GSH-PX) level of three treated groups against the normal control group (NC) fed with basal diet significantly increased by 3.89-24.49%, 0.53-7.39%, and 0.79-11.79%, respectively. While the malondialdehyde (MDA) decreased by 0.47-18.27%. Compared with the NC, the feed to gain ratio (F : G) of three treated groups was lowered by 2.98-16.53% and survival rate of broilers significantly increased. Consequently, 75% EEFs extracted from alfalfa exhibited powerful antioxidant activities and might be a potential feed additive to poultry and livestock.


Assuntos
Antioxidantes/metabolismo , Flavonoides/metabolismo , Medicago sativa/metabolismo , Extratos Vegetais/metabolismo , Glutationa/metabolismo , Glutationa Peroxidase/metabolismo , Malondialdeído/metabolismo , Espectrometria de Massas , Superóxido Dismutase/metabolismo
13.
Sci Adv ; 6(5): eaax8254, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-32064339

RESUMO

Plant-microbe interactions are mediated by signaling compounds that control vital plant functions, such as nodulation, defense, and allelopathy. While interruption of signaling is typically attributed to biological processes, potential abiotic controls remain less studied. Here, we show that higher organic carbon (OC) contents in soils repress flavonoid signals by up to 70%. Furthermore, the magnitude of repression is differentially dependent on the chemical structure of the signaling molecule, the availability of metal ions, and the source of the plant-derived OC. Up to 63% of the signaling repression occurs between dissolved OC and flavonoids rather than through flavonoid sorption to particulate OC. In plant experiments, OC interrupts the signaling between a legume and a nitrogen-fixing microbial symbiont, resulting in a 75% decrease in nodule formation. Our results suggest that soil OC decreases the lifetime of flavonoids underlying plant-microbe interactions.


Assuntos
Carbono/metabolismo , Flavonoides/metabolismo , Medicago sativa/metabolismo , Microbiologia do Solo , Metais/metabolismo , Minerais/metabolismo , Nitrogênio/metabolismo , Fenômenos Fisiológicos Vegetais , Solo/química
14.
Ecotoxicol Environ Saf ; 191: 110206, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31954923

RESUMO

Heat stress is found to be a detrimental factor for growth and development of alfalfa (Medicago sativa L.) which is tremendously invaluable forage due to its high feed value and yield potential. Salicylic acid (SA) has been reported to play a pivotal role in the regulation of plants biotic and abiotic stress response. However, the role of exogenous SA in protecting alfalfa from heat-induced damage has rarely been studied. In this study, four-week-old alfalfa seedlings were treated with 0.25 mM or 0.5 mM SA five days prior to high stress treatment (three day), and various growth and physiological traits were measured. The results showed that exogenous SA pretreatment could improve leaf morphology, plant height, biomass, chlorophyll content, and photosynthetic efficiency of alfalfa under heat stress. Meanwhile, SA could alleviate heat-induced membrane damage by reducing electrolyte leakage (EL) and malondialdehyde (MDA) content, and regulate the activities of antioxidant enzymes including catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD). The results revealed that exogenous SA application enhanced alfalfa heat tolerance by modulating various morphological and physiological characteristics under heat stress, with more prominent effect at lower concentration (0.25 mM). Overall, this study provides fundamental insights into the SA-mediated physiological adaptation of alfalfa plants to heat stress, which could have useful implication in managing other plants which are suffering global warming.


Assuntos
Resposta ao Choque Térmico/efeitos dos fármacos , Medicago sativa/efeitos dos fármacos , Ácido Salicílico/farmacologia , Antioxidantes/metabolismo , Catalase/metabolismo , Clorofila/metabolismo , Malondialdeído/metabolismo , Medicago sativa/crescimento & desenvolvimento , Medicago sativa/metabolismo , Peroxidase/metabolismo , Fotossíntese/efeitos dos fármacos , Superóxido Dismutase/metabolismo
15.
Microbiology (Reading) ; 166(3): 278-287, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31935179

RESUMO

In nitrogen-fixing rhizobia, emerging evidence shows significant roles for polyamines in growth and abiotic stress resistance. In this work we show that a polyamine-deficient ornithine decarboxylase null mutant (odc2) derived from Sinorhizobium meliloti Rm8530 had significant phenotypic differences from the wild-type, including greatly reduced production of exopolysaccharides (EPS; ostensibly both succinoglycan and galactoglucan), increased sensitivity to oxidative stress and decreased swimming motility. The introduction of the odc2 gene borne on a plasmid into the odc2 mutant restored wild-type phenotypes for EPS production, growth under oxidative stress and swimming. The production of calcofluor-binding EPS (succinoglycan) by the odc2 mutant was also completely or mostly restored in the presence of exogenous spermidine (Spd), norspermidine (NSpd) or spermine (Spm). The odc2 mutant formed about 25 % more biofilm than the wild-type, and its ability to form biofilm was significantly inhibited by exogenous Spd, NSpd or Spm. The odc2 mutant formed a less efficient symbiosis with alfalfa, resulting in plants with significantly less biomass and height, more nodules but less nodule biomass, and 25 % less nitrogen-fixing activity. Exogenously supplied Put was not able to revert these phenotypes and caused a similar increase in plant height and dry weight in uninoculated plants and in those inoculated with the wild-type or odc2 mutant. We discuss ways in which polyamines might affect the phenotypes of the odc2 mutant.


Assuntos
Medicago sativa/microbiologia , Ornitina Descarboxilase/genética , Poliaminas/metabolismo , Nódulos Radiculares de Plantas , Sinorhizobium meliloti/genética , Proteínas de Bactérias/genética , Medicago sativa/crescimento & desenvolvimento , Medicago sativa/metabolismo , Mutação , Nitrogênio/metabolismo , Fenótipo , Polissacarídeos Bacterianos/metabolismo , Nódulos Radiculares de Plantas/metabolismo , Nódulos Radiculares de Plantas/microbiologia , Sinorhizobium meliloti/metabolismo
16.
Ecotoxicol Environ Saf ; 190: 110176, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31927358

RESUMO

Jasmonic acid (JA) is an important phytohormone, which among others may be involved in the regulation of plant accumulating heavy metal. This experiment was designed to explore the effects of exogenous JA on the responses of alfalfa to Cu stress (100 µM) in Hoagland solution. When 1, 5 or 10 mM JA was added to the treatment with Cu addition, Cu concentrations in roots and leaves of alfalfa were significantly decreased (p < 0.05) to some extents compared to the treatment without JA addition. The biomasses of roots and leaves of alfalfa in treatments of JA additions were significantly increased (p < 0.05) compared to the Cu stress treatment. Similarly, the concentrations of Chlorophyll, antioxidant enzyme activities, MDA and H2O2 were improved accordingly. But these factors of JA were not improved further when its concentration added in media was the highest (10 mM), indicating its improvement roles were limited. These results suggested that there were positive roles of exogenous JA on alfalfa decreased its Cu accumulation and toxicities might via reduced oxidative stress.


Assuntos
Cobre/toxicidade , Ciclopentanos/farmacologia , Medicago sativa/efeitos dos fármacos , Oxilipinas/farmacologia , Reguladores de Crescimento de Planta/farmacologia , Clorofila/metabolismo , Peróxido de Hidrogênio/metabolismo , Malondialdeído/metabolismo , Medicago sativa/metabolismo , Fotossíntese , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo
17.
BMC Plant Biol ; 20(1): 15, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31914920

RESUMO

BACKGROUND: Alfalfa is a high-quality forage cultivated widely in northern China. Recently, the failure of alfalfa plants to survive the winter has caused substantial economic losses. Water management has attracted considerable attention as a method for the potential improvement of winter survival. The aim of this study was to determine whether and how changes in the water regime affect the freezing tolerance of alfalfa. RESULTS: The alfalfa variety WL353LH was cultivated under water regimes of 80 and 25% of water-holding capacity, and all the plants were subjected to low temperatures at 4/0 °C (light/dark) and then - 2/- 6 °C (light/dark). The semi-lethal temperatures were lower for water-stressed than well-watered alfalfa. The pool sizes of total soluble sugars, total amino acids, and proline changed substantially under water-deficit and low-temperature conditions. Metabolomics analyses revealed 72 subclasses of differential metabolites, among which lipid and lipid-like molecules (e.g., fatty acids, unsaturated fatty acids, and glycerophospholipids) and amino acids, peptides, and analogues (e.g., proline betaine) were upregulated under water-deficit conditions. Some carbohydrates (e.g., D-maltose and raffinose) and flavonoids were also upregulated at low temperatures. Finally, Kyoto Encyclopedia of Genes and Genomes analyses revealed 18 significantly enriched pathways involved in the biosynthesis and metabolism of carbohydrates, unsaturated fatty acids, amino acids, and glycerophospholipids. CONCLUSIONS: Water deficit significantly enhanced the alfalfa' freezing tolerance, and this was correlated with increased soluble sugar, amino acid, and lipid and lipid-like molecule contents. These substances are involved in osmotic regulation, cryoprotection, and the synthesis, fluidity, and stability of the cellular membrane. Our study provides a reference for improving alfalfa' winter survival through water management.


Assuntos
Resposta ao Choque Frio/fisiologia , Medicago sativa/metabolismo , Metabolômica , Água/metabolismo , Aminoácidos/metabolismo , Metabolismo dos Carboidratos/genética , China , Temperatura Baixa , Congelamento , Perfilação da Expressão Gênica , Metabolismo dos Lipídeos/genética , Medicago sativa/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estresse Fisiológico/fisiologia
18.
Arch Microbiol ; 202(2): 391-398, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31680188

RESUMO

Bacterial surface molecules have an important role in the rhizobia-legume symbiosis. Ensifer meliloti (previously, Sinorhizobium meliloti), a symbiotic Gram-negative rhizobacterium, produces two different exopolysaccharides (EPSs), termed EPS I (succinoglycan) and EPS II (galactoglucan), with different functions in the symbiotic process. Accordingly, we undertook a study comparing the potential differences in alfalfa nodulation by E. meliloti strains with differences in their EPSs production. Strains recommended for inoculation as well as laboratory strains and native strains isolated from alfalfa fields were investigated. This study concentrated on EPS-II production, which results in mucoid colonies that are dependent on the presence of an intact expR gene. The results revealed that although the studied strains exhibited different phenotypes, the differences did not affect alfalfa nodulation itself. However, subtle changes in timing and efficacy to the effects of inoculation with the different strains may result because of other as-yet unknown factors. Thus, additional research is needed to determine the most effective inoculant strains and the best conditions for improving alfalfa production under agricultural conditions.


Assuntos
Galactanos/metabolismo , Glucanos/metabolismo , Medicago sativa/metabolismo , Medicago sativa/microbiologia , Polissacarídeos Bacterianos/metabolismo , Sinorhizobium meliloti/metabolismo , Proteínas de Bactérias/genética , Fertilizantes/microbiologia , Regulação Bacteriana da Expressão Gênica , Nodulação/fisiologia , Simbiose/fisiologia
19.
Food Chem ; 309: 125786, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31704078

RESUMO

The ultrasonic-assisted extraction of total saponins from alfalfa leaves was optimised by the simultaneous maximization of the yield and bioaccessibility as a factor with increasingly great relevance in the biological activity by Response Surface Methodology. The kinetics of total saponins and bioaccessibility were investigated for the optimum ultrasound-assisted method compared to conventional method by the pseudo-first order model. The optimum extraction conditions were of solvent/raw material ratio of 11.4 mL/g, extraction time of 2.84 h, extraction temperature of 76.8 °C, ultrasound power of 112.0 w and ethanol concentration of 78.2%. The yield of total saponins and bioaccessibility was 1.61 and 18.6%, respectively. The yield rate constant for the ultrasound extraction was almost two times more than that of the heat-reflux method. Ultrasonic-assisted extraction, comparing to conventional method, had greater efficiency for the extraction yield and bioaccessibility of total saponins.


Assuntos
Medicago sativa/química , Saponinas/análise , Sonicação , Etanol/química , Cinética , Medicago sativa/metabolismo , Extratos Vegetais/química , Folhas de Planta/química , Folhas de Planta/metabolismo , Saponinas/isolamento & purificação , Solventes/química
20.
J Sci Food Agric ; 100(5): 1922-1930, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31846083

RESUMO

BACKGROUND: Ten varieties of alfalfa (Medicago sativa L.) were evaluated for saponin content. Two of the most promising varieties were chosen so that their effect on rumen fermentation and methane production could be studied. Initially, four Hohenheim gas tests (HGT) were performed to test the effect of increased levels of total saponin extracted from the two alfalfa cultivars (Kometa and Verko) - either as fresh material or ensiled - on the total bacteria, total protozoa, methane emission, and selected methanogenic population. Afterwards, seven particular saponins were extracted from fresh alfalfa of the Kometa variety and tested in 24 h batch fermentation culture experiments. RESULTS: The ensiled forms of both the Verko and Kometa alfalfa varieties seem to be good sources of saponin, capable of reducing methane production (P < 0.05) without negatively affecting the basic fermentation parameters. Of the two evaluated varieties, Kometa was the most effective, and the saponins extracted from its roots 3-Glc,28-Glc Ma, medicagenic saponin, and 3-Glu Ma showed the most evident effect (P = 0.0001). The most promising aerial alfalfa saponin in mitigating methane production was soysaponin I K salt (P = 0.0001). Three mixtures of saponins were tested and all were found to mitigate methane production; however, one mixture (MIX 1) did so only to a very small extent. CONCLUSION: Saponins have been observed to have differing effects depending on their source; however, the mode of action of saponins depends on their direct or probable indirect effect on the microorganisms involved in methane production. © 2019 Society of Chemical Industry.


Assuntos
Bovinos/metabolismo , Medicago sativa/metabolismo , Metano/metabolismo , Rúmen/metabolismo , Saponinas/metabolismo , Ração Animal/análise , Animais , Digestão , Fermentação , Medicago sativa/química , Metano/análise , Saponinas/análise
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