Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.811
Filtrar
1.
Science ; 373(6556): 774-779, 2021 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-34385392

RESUMO

The oomycete Phytophthora infestans is a damaging crop pathogen and a model organism to study plant-pathogen interactions. We report the discovery of a family of copper-dependent lytic polysaccharide monooxygenases (LPMOs) in plant pathogenic oomycetes and its role in plant infection by P. infestans We show that LPMO-encoding genes are up-regulated early during infection and that the secreted enzymes oxidatively cleave the backbone of pectin, a charged polysaccharide in the plant cell wall. The crystal structure of the most abundant of these LPMOs sheds light on its ability to recognize and degrade pectin, and silencing the encoding gene in P. infestans inhibits infection of potato, indicating a role in host penetration. The identification of LPMOs as virulence factors in pathogenic oomycetes opens up opportunities in crop protection and food security.


Assuntos
Lycopersicon esculentum/parasitologia , Oxigenases de Função Mista/metabolismo , Pectinas/metabolismo , Phytophthora infestans/enzimologia , Doenças das Plantas/parasitologia , Solanum tuberosum/parasitologia , Cobre , Oxigenases de Função Mista/química , Oxigenases de Função Mista/genética , Modelos Moleculares , Oxirredução , Phytophthora infestans/genética , Phytophthora infestans/patogenicidade , Folhas de Planta/parasitologia , Polissacarídeos/metabolismo , Conformação Proteica , Domínios Proteicos , Fatores de Virulência/química , Fatores de Virulência/genética , Fatores de Virulência/metabolismo
2.
Molecules ; 26(9)2021 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-34068822

RESUMO

The contribution of rheological properties and viscoelasticity of the interfacial adsorbed layer to the emulsification mechanism of enzymatic modified sugar beet pectin (SBP) was studied. The component content of each enzymatic modified pectin was lower than that of untreated SBP. Protein and ferulic acid decreased from 5.52% and 1.08% to 0.54% and 0.13%, respectively, resulting in a decrease in thermal stability, apparent viscosity, and molecular weight (Mw). The dynamic interfacial rheological properties showed that the interfacial pressure and modulus (E) decreased significantly with the decrease of functional groups (especially proteins), which also led to the bimodal distribution of particle size. These results indicated that the superior emulsification property of SBP is mainly determined by proteins, followed by ferulic acid, and the existence of other functional groups also promotes the emulsification property of SBP.


Assuntos
Beta vulgaris/química , Emulsões/química , Enzimas/metabolismo , Pectinas/metabolismo , Reologia , Adsorção , Difusão , Elasticidade , Cinética , Peso Molecular , Óleos/química , Tamanho da Partícula , Pressão , Espectroscopia de Prótons por Ressonância Magnética , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Termogravimetria , Fatores de Tempo , Viscosidade , Água/química
3.
Plant Cell ; 33(3): 581-602, 2021 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-33955485

RESUMO

Plants possess unique primary cell walls made of complex polysaccharides that play critical roles in determining intrinsic cell and organ size. How genes responsible for synthesizing and modifying the polysaccharides in the cell wall are regulated by microRNAs (miRNAs) to control plant size remains largely unexplored. Here we identified 23 putative cell wall-related miRNAs, termed as CW-miRNAs, in Arabidopsis thaliana and characterized miR775 as an example. We showed that miR775 post-transcriptionally silences GALT9, which encodes an endomembrane-located galactosyltransferase belonging to the glycosyltransferase 31 family. Over-expression of miR775 and deletion of GALT9 led to significantly enlarged leaf-related organs, primarily due to increased cell size. Monosaccharide quantification, confocal Raman imaging, and immunolabeling combined with atomic force microscopy revealed that the MIR775A-GALT9 circuit modulates pectin levels and the elastic modulus of the cell wall. We also showed that MIR775A is directly repressed by the transcription factor ELONGATED HYPOCOTYL5 (HY5). Genetic analysis confirmed that HY5 is a negative regulator of leaf size that acts through the HY5-MIR775A-GALT9 repression cascade to control pectin levels. These findings demonstrate that miR775-regulated cell wall remodeling is an integral determinant of intrinsic leaf size in A. thaliana. Studying other CW-miRNAs would provide more insights into cell wall biology.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Parede Celular/metabolismo , Galactosiltransferases/metabolismo , Pectinas/metabolismo , Folhas de Planta/metabolismo , Plantas Geneticamente Modificadas/metabolismo , Proteínas de Arabidopsis/genética , Galactosiltransferases/genética , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente Modificadas/genética
4.
BMC Plant Biol ; 21(1): 245, 2021 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-34051740

RESUMO

BACKGROUND: Arabinogalactan-proteins (AGPs) are heavily glycosylated with type II arabinogalactan (AG) polysaccharides attached to hydroxyproline residues in their protein backbone. Type II AGs are necessary for plant growth and critically important for the establishment of normal cellular functions. Despite the importance of type II AGs in plant development, our understanding of the underlying role of these glycans/sugar residues in mucilage formation and seed coat epidermal cell development is poorly understood and far from complete. One such sugar residue is the glucuronic acid residues of AGPs that are transferred onto AGP glycans by the action of ß-glucuronosyltransferase genes/enzymes. RESULTS: Here, we have characterized two ß-glucuronosyltransferase genes, GLCAT14A and GLCAT14C, that are involved in the transfer of ß-glucuronic acid (GlcA) to type II AGs. Using a reverse genetics approach, we observed that glcat14a-1 mutants displayed subtle alterations in mucilage pectin homogalacturonan (HG) compared to wild type (WT), while glcat14a-1glcat14c-1 mutants displayed much more severe mucilage phenotypes, including loss of adherent mucilage and significant alterations in cellulose ray formation and seed coat morphology. Monosaccharide composition analysis showed significant alterations in the sugar amounts of glcat14a-1glcat14c-1 mutants relative to WT in the adherent and non-adherent seed mucilage. Also, a reduction in total mucilage content was observed in glcat14a-1glcat14c-1 mutants relative to WT. In addition, glcat14a-1glcat14c-1 mutants showed defects in pectin formation, calcium content and the degree of pectin methyl-esterification (DM) as well as reductions in crystalline cellulose content and seed size. CONCLUSIONS: These results raise important questions regarding cell wall polymer interactions and organization during mucilage formation. We propose that the enzymatic activities of GLCAT14A and GLCAT14C play partially redundant roles and are required for the organization of the mucilage matrix and seed size in Arabidopsis thaliana. This work brings us a step closer towards identifying potential gene targets for engineering plant cell walls for industrial applications.


Assuntos
Arabidopsis/enzimologia , Galactanos/metabolismo , Glucuronosiltransferase/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Cálcio/metabolismo , Parede Celular/metabolismo , Celulose/metabolismo , Esterificação , Glucuronosiltransferase/genética , Monossacarídeos/metabolismo , Pectinas/metabolismo , Fenótipo , Polissacarídeos/metabolismo , Sementes/enzimologia , Sementes/genética
5.
PLoS One ; 16(5): e0250650, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33951055

RESUMO

The primary plant cell wall is a complex matrix composed of interconnected polysaccharides including cellulose, hemicellulose, and pectin. Changes of this dynamic polysaccharide system play a critical role during plant cell development and differentiation. A better understanding of cell wall architectures can provide insight into the plant cell development. In this study, a Raman spectroscopic imaging approach was developed to visualize the distribution of plant cell wall polysaccharides. In this approach, Surface-enhanced Raman scattering (SERS through self-assembled silver nanoparticles) was combined with Raman labels (4-Aminothiophenol. 4ATP) and targeted enzymatic hydrolysis to improve the sensitivity, specificity, and throughput of the Raman imaging technique, and to reveal the distribution of pectin and its co-localization with xyloglucan inside onion epidermal cell (OEC) wall. This technique significantly decreased the required spectral acquisition time. The resulted Raman spectra showed a high Raman signal. The resulted Raman images successfully revealed and characterized the pectin distribution and its co-localization pattern with xyloglucan in OEC wall.


Assuntos
Parede Celular/metabolismo , Glucanos/metabolismo , Cebolas/citologia , Pectinas/metabolismo , Epiderme Vegetal/citologia , Análise Espectral Raman , Xilanos/metabolismo , Transporte Proteico
6.
Development ; 148(10)2021 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-34015094

RESUMO

Plant growth, morphogenesis and development involve cellular adhesion, a process dependent on the composition and structure of the extracellular matrix or cell wall. Pectin in the cell wall is thought to play an essential role in adhesion, and its modification and cleavage are suggested to be highly regulated so as to change adhesive properties. To increase our understanding of plant cell adhesion, a population of ethyl methanesulfonate-mutagenized Arabidopsis were screened for hypocotyl adhesion defects using the pectin binding dye Ruthenium Red that penetrates defective but not wild-type (WT) hypocotyl cell walls. Genomic sequencing was used to identify a mutant allele of ELMO1 which encodes a 20 kDa Golgi membrane protein that has no predicted enzymatic domains. ELMO1 colocalizes with several Golgi markers and elmo1-/- plants can be rescued by an ELMO1-GFP fusion. elmo1-/- exhibits reduced mannose content relative to WT but no other cell wall changes and can be rescued to WT phenotype by mutants in ESMERALDA1, which also suppresses other adhesion mutants. elmo1 describes a previously unidentified role for the ELMO1 protein in plant cell adhesion.


Assuntos
Arabidopsis/embriologia , Adesão Celular/genética , Adesão Celular/fisiologia , Complexo de Golgi/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Parede Celular/metabolismo , Regulação da Expressão Gênica de Plantas/genética , Complexo de Golgi/genética , Hipocótilo/citologia , Hipocótilo/genética , Manose/análise , Proteínas de Membrana/genética , Metiltransferases/genética , Pectinas/metabolismo
7.
Plant Physiol ; 185(3): 914-933, 2021 04 02.
Artigo em Inglês | MEDLINE | ID: mdl-33793913

RESUMO

Rhamnogalacturonan-I biosynthesis occurs in the lumen of the Golgi apparatus, a compartment where UDP-Rhamnose and UDP-Galacturonic Acid are the main substrates for synthesis of the backbone polymer of pectin. Recent studies showed that UDP-Rha is transported from the cytosol into the Golgi apparatus by a family of six UDP-rhamnose/UDP-galactose transporters (URGT1-6). In this study, analysis of adherent and soluble mucilage (SM) of Arabidopsis thaliana seeds revealed distinct roles of URGT2, URGT4, and URGT6 in mucilage biosynthesis. Characterization of SM polymer size showed shorter chains in the urgt2 urgt4 and urgt2 urgt4 urgt6 mutants, suggesting that URGT2 and URGT4 are mainly involved in Rhamnogalacturonan-I (RG-I) elongation. Meanwhile, mutants in urgt6 exhibited changes only in adherent mucilage (AM). Surprisingly, the estimated number of RG-I polymer chains present in urgt2 urgt4 and urgt2 urgt4 urgt6 mutants was higher than in wild-type. Interestingly, the increased number of shorter RG-I chains was accompanied by an increased amount of xylan. In the urgt mutants, expression analysis of other genes involved in mucilage biosynthesis showed some compensation. Studies of mutants of transcription factors regulating mucilage formation indicated that URGT2, URGT4, and URGT6 are likely part of a gene network controlled by these regulators and involved in RG-I synthesis. These results suggest that URGT2, URGT4, and URGT6 play different roles in the biosynthesis of mucilage, and the lack of all three affects the production of shorter RG-I polymers and longer xylan domains.


Assuntos
Proteínas de Arabidopsis/metabolismo , Proteínas de Transporte de Monossacarídeos/metabolismo , Pectinas/metabolismo , Ramnogalacturonanos/metabolismo , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Proteínas de Transporte de Monossacarídeos/genética , N-Glicosil Hidrolases/genética , N-Glicosil Hidrolases/metabolismo
8.
Carbohydr Polym ; 262: 117943, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33838820

RESUMO

Aspergillus spp. are well-known producers of pectinases commonly used in the industry. Aspergillus aculeatinus is a recently identified species but poorly characterized. This study aimed at giving a comprehensive characterization of the enzymatic potential of the O822 strain to produce Rhamnogalacturonan type I (RGI)-degrading enzymes. Proteomic analysis identified cell wall degrading enzymes (cellulases, hemicellulases, and pectinases) that accounted for 92 % of total secreted proteins. Twelve out of fifty proteins were identified as RGI-degrading enzymes. NMR and enzymatic assays revealed high levels of arabinofuranosidase, arabinanase, galactanase, rhamnogalacturonan hydrolases and rhamnogalacturonan acetylesterase activities in aqueous extracts. Viscosity assays carried out with RGI-rich camelina mucilage confirmed the efficiency of enzymes secreted by O822 to hydrolyze RGI, by decreasing viscosity by 70 %. Apple juice trials carried out at laboratory and pilot scale showed an increase in filtration flow rate and yield, paving the way for an industrial use of enzymes derived from A. aculeatinus.


Assuntos
Aspergillus/enzimologia , Filtração/métodos , Sucos de Frutas e Vegetais , Proteínas Fúngicas/metabolismo , Ramnogalacturonanos/metabolismo , Metabolismo dos Carboidratos , Celulases/metabolismo , Manipulação de Alimentos/métodos , Glicosídeo Hidrolases/metabolismo , Hidrolases/metabolismo , Malus , Pectinas/metabolismo , Poligalacturonase/metabolismo , Proteômica
9.
Int J Mol Sci ; 22(6)2021 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-33809409

RESUMO

Yellow lupine is a great model for abscission-related research given that excessive flower abortion reduces its yield. It has been previously shown that the EPIP peptide, a fragment of LlIDL (INFLORESCENCE DEFICIENT IN ABSCISSION) amino-acid sequence, is a sufficient molecule to induce flower abortion, however, the question remains: What are the exact changes evoked by this peptide locally in abscission zone (AZ) cells? Therefore, we used EPIP peptide to monitor specific modifications accompanied by early steps of flower abscission directly in the AZ. EPIP stimulates the downstream elements of the pathway-HAESA and MITOGEN-ACTIVATED PROTEIN KINASE6 and induces cellular symptoms indicating AZ activation. The EPIP treatment disrupts redox homeostasis, involving the accumulation of H2O2 and upregulation of the enzymatic antioxidant system including superoxide dismutase, catalase, and ascorbate peroxidase. A weakening of the cell wall structure in response to EPIP is reflected by pectin demethylation, while a changing pattern of fatty acids and acyl lipids composition suggests a modification of lipid metabolism. Notably, the formation of a signaling molecule-phosphatidic acid is induced locally in EPIP-treated AZ. Collectively, all these changes indicate the switching of several metabolic and signaling pathways directly in the AZ in response to EPIP, which inevitably leads to flower abscission.


Assuntos
Flores/crescimento & desenvolvimento , Homeostase , Lipídeos/química , Lupinus/crescimento & desenvolvimento , Pectinas/metabolismo , Peptídeos/farmacologia , Parede Celular/efeitos dos fármacos , Parede Celular/metabolismo , Flores/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Peróxido de Hidrogênio/metabolismo , Lupinus/efeitos dos fármacos , Oxirredução , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Transdução de Sinais/efeitos dos fármacos , Superóxido Dismutase/metabolismo
10.
Planta ; 253(5): 92, 2021 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-33821335

RESUMO

MAIN CONCLUSION: The cell wall protein CpWAK1 interacts with pectin, participates in decoding cell wall signals, and induces different downstream responses. Cell wall-associated protein kinases (WAKs) are transmembrane receptor kinases. In the desiccation-tolerant resurrection plant Craterostigma plantagineum, CpWAK1 has been shown to be involved in stress responses and cell expansion by forming a complex with the C. plantagineum glycine-rich protein1 (CpGRP1). This prompted us to extend the studies of WAK genes in C. plantagineum. The phylogenetic analyses of WAKs from C. plantagineum and from other species suggest that these genes have been duplicated after species divergence. Expression profiles indicate that CpWAKs are involved in various biological processes, including dehydration-induced responses and SA- and JA-related reactions to pathogens and wounding. CpWAK1 shows a high affinity for "egg-box" pectin structures. ELISA assays revealed that the binding of CpWAKs to pectins is modulated by CpGRP1 and it depends on the apoplastic pH. The formation of CpWAK multimers is the prerequisite for the CpWAK-pectin binding. Different pectin extracts lead to opposite trends of CpWAK-pectin binding in the presence of Ca2+ at pH 8. These observations demonstrate that CpWAKs can potentially discriminate and integrate cell wall signals generated by diverse stimuli, in concert with other elements, such as CpGRP1, pHapo, Ca2+[apo], and via the formation of CpWAK multimers.


Assuntos
Parede Celular/metabolismo , Craterostigma/enzimologia , Meio Ambiente , Pectinas/metabolismo , Proteínas Quinases/metabolismo , Filogenia
11.
Carbohydr Polym ; 264: 118040, 2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-33910723

RESUMO

Citrus pectin can serve as a naturally digestion-resistant emulsifier, although how it achieves this effect is still unknown. In this study, the upper digestion fate of an emulsion stabilized by different concentrations of citrus pectin, and changes in its interfacial properties during digestion, were investigated. Emulsions stabilized by high-concentration citrus pectin (3 %) were relatively stable during digestion and had a lower free fatty acid (FFA) release rate than emulsions stabilized by low-concentration citrus pectin (1 %). At the low concentration, the citrus pectin interface had a thin absorbing layer and was largely replaced by bile salts, while at high concentration the citrus pectin interface possessed a uniform and thick adsorbing layer that resisted the replacement of bile salts and enabled lipase adsorption. This study has improved our understanding of the digestion of emulsion from the interface and will be useful for designing emulsion-based functional foods that can achieve targeted release.


Assuntos
Citrus/química , Digestão , Emulsificantes/química , Pectinas/química , Trato Gastrointestinal Superior/metabolismo , Adsorção , Ácidos e Sais Biliares/metabolismo , Emulsificantes/metabolismo , Emulsões/química , Ácidos Graxos não Esterificados/metabolismo , Humanos , Lipase/metabolismo , Lipólise , Microscopia Confocal/métodos , Microscopia Eletrônica de Transmissão/métodos , Pectinas/metabolismo , Amido/metabolismo , Proteínas do Soro do Leite/metabolismo
12.
Carbohydr Polym ; 260: 117824, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712165

RESUMO

Rhamnogalacturonan I (RG-I) enriched pectic polysaccharides were extracted from Cerasus humilis fruits (RPCF, RG-I: 74.46 %). Structural characterization including FTIR, XRD, NMR, HPAEC and SEM demonstrated that RPCF was a high-methoxy acetylated pectin macromolecule with abundant arabinose and galactose side chains (DM: 53.41 %, MW: 1098 kDa, (Ara + Gal)/Rha: 5.37 %). RPCF afforded additional lipid oxidation stability for emulsions, and exhibited significantly better emulsification performance than citrus pectin. In addition, RPCF formed a weak gel network that stabilized the emulsions (G' > G″). Interestingly, RPCF had behaviors that are divergent from those of commercial high-methoxy pectin because it demonstrated potential in forming sugar-free gels systems. Overall, Cerasus humilis is a new source of pectin rich in RG-I. RPCF can be used as a novel emulsifier with gelling and antioxidant effects, providing its alternative application as a natural emulsifier and rheological modifier in a wide range of products, including those with oil-in-water and low sugar.


Assuntos
Pectinas/química , Polissacarídeos/química , Prunus/metabolismo , Antioxidantes/química , Emulsificantes/química , Emulsões/química , Peso Molecular , Pectinas/análise , Pectinas/metabolismo , Polissacarídeos/análise , Polissacarídeos/metabolismo , Reologia
13.
Carbohydr Polym ; 260: 117711, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712120

RESUMO

The metabolites produced by plants can be enhanced by plant tissue culture. In Premma puberula Pamp., the pectin content in leaves is 30 %-40 %, and it is widely used in the food industry and medicine. However, inefficient propagation has seriously restricted the utilization of pectin resources. Therefore, we established an efficient micropropagation technology for P. puberula through comparative analysis in mature leaves of regenerated and conventionally propagated plants. The results showed that the pectin composition of their leaves was similar in terms of galacturonic acid, monosaccharide composition, degree of esterification, functional groups, nuclear magnetic resonance spectrum and morphological characteristics. Furthermore, micropropagated plants had better hardness, gumminess and chewiness characteristics than conventionally propagated plants and were similar in emulsion stability, adhesiveness, springiness, cohesiveness and viscoelasticity. Therefore, micropropagation technology will provide an important guarantee for the industrial production of pectin from P. puberula. The technical essentials include callus induction, embryoid formation, and root induction, followed by acclimatization and transplanting.


Assuntos
Lamiaceae/metabolismo , Pectinas/metabolismo , Emulsificantes/química , Esterificação , Ácidos Hexurônicos/análise , Lamiaceae/citologia , Monossacarídeos/análise , Pectinas/química , Pectinas/isolamento & purificação , Folhas de Planta/citologia , Folhas de Planta/metabolismo , Viscosidade
14.
Plant Cell ; 33(2): 381-403, 2021 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-33709105

RESUMO

Homogalacturonan (HG), a component of pectin, is synthesized in the Golgi apparatus in its fully methylesterified form. It is then secreted into the apoplast where it is typically de-methylesterified by pectin methylesterases (PME). Secretion and de-esterification are critical for normal pectin function, yet the underlying transcriptional regulation mechanisms remain largely unknown. Here, we uncovered a mechanism that fine-tunes the degree of HG de-methylesterification (DM) in the mucilage that surrounds Arabidopsis thaliana seeds. We demonstrate that the APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factor (TF) ERF4 is a transcriptional repressor that positively regulates HG DM. ERF4 expression is confined to epidermal cells in the early stages of seed coat development. The adhesiveness of the erf4 mutant mucilage was decreased as a result of an increased DM caused by a decrease in PME activity. Molecular and genetic analyses revealed that ERF4 positively regulates HG DM by suppressing the expression of three PME INHIBITOR genes (PMEIs) and SUBTILISIN-LIKE SERINE PROTEASE 1.7 (SBT1.7). ERF4 shares common targets with the TF MYB52, which also regulates pectin DM. Nevertheless, the erf4-2 myb52 double mutant seeds have a wild-type mucilage phenotype. We provide evidence that ERF4 and MYB52 regulate downstream gene expression in an opposite manner by antagonizing each other's DNA-binding ability through a physical interaction. Together, our findings reveal that pectin DM in the seed coat is fine-tuned by an ERF4-MYB52 transcriptional complex.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas de Membrana/metabolismo , Pectinas/metabolismo , Mucilagem Vegetal/metabolismo , Proteínas Repressoras/metabolismo , Sementes/metabolismo , Fatores Genéricos de Transcrição/metabolismo , Adesividade , Arabidopsis/embriologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Cálcio/metabolismo , Hidrolases de Éster Carboxílico/metabolismo , Reagentes para Ligações Cruzadas/química , Esterificação , Genes de Plantas , Mutação/genética , Motivos de Nucleotídeos/genética , Fenótipo , Epiderme Vegetal/citologia , Epiderme Vegetal/metabolismo , Ligação Proteica , Proteínas Repressoras/genética
15.
Int J Biol Macromol ; 176: 165-176, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33561463

RESUMO

Pectin, the major non-cellulosic component of primary cell wall can be degraded by polygalacturonases (PGs) and pectin methylesterases (PMEs) during pathogen attack on plants. We characterized two novel enzymes, VdPG2 and VdPME1, from the fungal plant pathogen Verticillium dahliae. VdPME1 was most active on citrus methylesterified pectin (55-70%) at pH 6 and a temperature of 40 °C, while VdPG2 was most active on polygalacturonic acid at pH 5 and a temperature of 50 °C. Using LC-MS/MS oligoprofiling, and various pectins, the mode of action of VdPME1 and VdPG2 were determined. VdPME1 was shown to be processive, in accordance with the electrostatic potential of the enzyme. VdPG2 was identified as endo-PG releasing both methylesterified and non-methylesterified oligogalacturonides (OGs). Additionally, when flax roots were used as substrate, acetylated OGs were detected. The comparisons of OGs released from Verticillium-susceptible and partially resistant flax cultivars identified new possible elicitor of plant defence responses.


Assuntos
Ascomicetos/enzimologia , Hidrolases de Éster Carboxílico/metabolismo , Proteínas Fúngicas/metabolismo , Poligalacturonase/metabolismo , Ascomicetos/genética , Ascomicetos/patogenicidade , Hidrolases de Éster Carboxílico/química , Hidrolases de Éster Carboxílico/genética , Linho/metabolismo , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Cinética , Modelos Moleculares , Pectinas/metabolismo , Filogenia , Doenças das Plantas/microbiologia , Raízes de Plantas/metabolismo , Poligalacturonase/química , Poligalacturonase/genética , Eletricidade Estática , Especificidade por Substrato
16.
Int J Biol Macromol ; 175: 443-450, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33556396

RESUMO

Plant-derived polysaccharides possess potential health benefits that improve intestinal health and the immune system. Molokhia leaves have a large amount of mucilage polysaccharide; in the present study, crude polysaccharide extract was prepared from molokhia leaves. The molecular weight of molokhia leaf polysaccharide fraction (MPF) was estimated to be 51.2 × 103 Da. Polysaccharide was methylated and the structure of MPF was mainly composed of rhamnogalacturonan-I structure with side chains, such as galactans and linear glucan (starch), as shown by GC-MS analysis. To study the biofunctional effects of MPF, its prebiotic and intestinal immune-enhancing activities were assayed in vitro. MPF exhibited good prebiotic activity, as shown by its high prebiotic scores, and increased contents of total short-chain fatty acids on five probiotic strains. In addition, MPF showed immune-enhancing activity on Peyer's patches, as revealed by the high bone marrow cell proliferating activity and production of immunoglobulin A and cytokines. These results demonstrate that MPF may be a potential beneficial prebiotic and intestinal immune-enhancer, which may have wide implications in the food industry.


Assuntos
Corchorus/metabolismo , Pectinas/química , Pectinas/farmacologia , Animais , Medula Óssea/efeitos dos fármacos , Corchorus/química , Carboidratos da Dieta/farmacologia , Feminino , Galactanos/farmacologia , Cromatografia Gasosa-Espectrometria de Massas/métodos , Intestinos/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C3H , Pectinas/metabolismo , Extratos Vegetais/metabolismo , Folhas de Planta/química , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Polissacarídeos/química , Prebióticos
17.
J Integr Plant Biol ; 63(5): 865-877, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33615714

RESUMO

A series of nucleotide sugar interconversion enzymes (NSEs) generate the activated sugar donors required for biosynthesis of cell wall matrix polysaccharides and glycoproteins. UDP-glucose 4-epimerases (UGEs) are NSEs that function in the interconversion of UDP-glucose (UDP-Glc) and UDP-galactose (UDP-Gal). The roles of UDP-glucose 4-epimerases in monocots remain unclear due to redundancy in the pathways. Here, we report a brittle plant (bp1) rice mutant that exhibits brittle leaves and culms at all growth stages. The mutant culms had reduced levels of rhamnogalacturonan I, homogalacturonan, and arabinogalactan proteins. Moreover, the mutant had altered contents of uronic acids, neutral noncellulosic monosaccharides, and cellulose. Map-based cloning demonstrated that OsBP1 encodes a UDP-glucose 4-epimerase (OsUGE2), a cytosolic protein. We also show that BP1 can form homo- and hetero-protein complexes with other UGE family members and with UDP-galactose transporters 2 (OsUGT2) and 3 (OsUGT3), which may facilitate the channeling of Gal to polysaccharides and proteoglycans. Our results demonstrate that BP1 participates in regulating the sugar composition and structure of rice cell walls.


Assuntos
Parede Celular/metabolismo , Mucoproteínas/metabolismo , Oryza/metabolismo , UDPglucose 4-Epimerase/metabolismo , Regulação da Expressão Gênica de Plantas , Mucoproteínas/genética , Oryza/genética , Pectinas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , UDPglucose 4-Epimerase/genética
18.
Food Chem ; 351: 129294, 2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-33640774

RESUMO

Cell wall polysaccharides in fruits act a pivotal role in their resistance to fungal invasion. Lasiodiplodia theobromae (Pat.) Griff. & Maubl. is a primary pathogenic fungus causing the spoilage of fresh longan fruit. In this study, the influences of L. theobromae inoculation on the disassembly of cell wall polysaccharides in pericarp of fresh longans and its association with L. theobromae-induced disease and softening development were investigated. In contrast to the control, samples with L. theobromae infection showed more severe disease development, lower firmness, lower amounts of cell wall materials, covalent-soluble pectin, ionic-soluble pectin, cellulose and hemicellulose, whereas higher value of water-soluble pectin, higher activities of cell wall polysaccharide-disassembling enzymes (cellulase, ß-galactosidase, polygalacturonase and pectinesterase). These findings revealed that cell wall polysaccharides disassembly induced by enzymatic manipulation was an essential pathway for L. theobromae to infect harvested longans, and thus led to the disease occurrence and fruit softening.


Assuntos
Ascomicetos/fisiologia , Parede Celular/metabolismo , Polissacarídeos/metabolismo , Sapindaceae/microbiologia , Ascomicetos/enzimologia , Celulase/metabolismo , Celulose/análise , Celulose/metabolismo , Armazenamento de Alimentos , Frutas/química , Frutas/metabolismo , Frutas/microbiologia , Pectinas/metabolismo , Doenças das Plantas/microbiologia , Poligalacturonase/metabolismo , Polissacarídeos/análise , Sapindaceae/metabolismo
19.
Int J Biol Macromol ; 175: 123-130, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33548317

RESUMO

The study focused on assessing quality parameters of the surimi incorporated with soluble dietary fibers apple pectin and konjac glucomannan at different levels. The results showed that apple pectin at 0.025% and konjac glucomannan at a 2% level exhibited improved gel-forming ability significantly (p < 0.05). SDS- PAGE revealed high molecular weight protein crosslinks in apple pectin treated surimi gels and disappearance of myosin bands in konjac glucomannan treated surimi gels. The water holding capacity of surimi was the highest when 0.075 g/100 g of apple pectin was added. Konjac glucomannan treated gels exhibited superior whiteness values. The analysis of soluble protein revealed that hydrophobic bonds increased in both the treatments. The hardness values of pectin gels enhanced as the level increased. Other TPA parameters are shown an inconsistent trend. It can be demonstrated that the incorporation of apple pectin and konjac glucomannan at a level of 0.025 and 2.0% may be a novel strategy to improve the gel strength of the surimi.


Assuntos
Carpas/metabolismo , Mananas/química , Pectinas/química , Animais , Carpas/crescimento & desenvolvimento , Fibras na Dieta/análise , Produtos Pesqueiros/análise , Proteínas de Peixes/química , Aditivos Alimentares/química , Manipulação de Alimentos/métodos , Géis/química , Dureza , Malus/metabolismo , Mananas/metabolismo , Pectinas/metabolismo , Reologia , Água
20.
Ultrason Sonochem ; 72: 105465, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33497958

RESUMO

Ultrasound-assisted enzymatic maceration (UAEM) has gained considerable interest in the fruit juice industry, owing to its potential to increase juice yield and content of polyphenols while simultaneously saving time and energy. In this study, the effects of UAEM (ultrasonic probe, 20 kHz, 21 W*cm-2 and 33 W*cm-2) on pectin degradation in a continuous circulation system were investigated over 60 and 90 min. Main pectinolytic enzymes activities of (polygalacturonase, pectin lyase and pectin methylesterase) of a commercial enzyme preparation were examined for individual synergistic effects with US. Pectin hydrolysis by UAEM differed significantly compared to treatment with ultrasound or enzymes alone regarding the profile of degradation products compared to treatment with ultrasound or enzymes alone. Ultrasound fragmented pectin to less branched oligomers of medium molecular weight (Mp approx. 150 kDa), which were further degraded by pectinolytic activities. The low molecular weight fraction (<30 kDa), which is known to be beneficial for juice-quality by adding nutritional value and stabilizing polyphenols, was enriched in small oligomers of homogalacturonan-derived, rhamnogalacturonan I-derived, and rhamnogalacturonan II-derived residues. Synergistic effects of ultrasound application enhanced the effective activities of polygalacturonase and pectin lyase and even prolonged their performance over 90 min, whereas the effective activity of pectin methylesterase was not affected. Final marker concentrations determined by each enzyme assay revealed a considerable higher total process output after UAEM treatment at reduced temperature (30 °C) comparable to the output after conventional batch maceration at 50 °C. The obtained results demonstrate the high potential of UAEM to produce high-quality juice by controlling pectin degradation while reducing process temperature and equally highlight the matrix and enzyme specific effects of a simultaneous US treatment.


Assuntos
Enzimas/metabolismo , Manipulação de Alimentos/métodos , Pectinas/metabolismo , Ondas Ultrassônicas , Cinética , Temperatura
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...