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1.
BMC Plant Biol ; 19(1): 320, 2019 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-31319813

RESUMO

BACKGROUND: Plant cell walls participate in all plant-environment interactions. Maintaining cell wall integrity (CWI) during these interactions is essential. This realization led to increased interest in CWI and resulted in knowledge regarding early perception and signalling mechanisms active during CWI maintenance. By contrast, knowledge regarding processes mediating changes in cell wall metabolism upon CWI impairment is very limited. RESULTS: To identify genes involved and to investigate their contributions to the processes we selected 23 genes with altered expression in response to CWI impairment and characterized the impact of T-DNA insertions in these genes on cell wall composition using Fourier-Transform Infrared Spectroscopy (FTIR) in Arabidopsis thaliana seedlings. Insertions in 14 genes led to cell wall phenotypes detectable by FTIR. A detailed analysis of four genes found that their altered expression upon CWI impairment is dependent on THE1 activity, a key component of CWI maintenance. Phenotypic characterizations of insertion lines suggest that the four genes are required for particular aspects of CWI maintenance, cell wall composition or resistance to Plectosphaerella cucumerina infection in adult plants. CONCLUSION: Taken together, the results implicate the genes in responses to CWI impairment, cell wall metabolism and/or pathogen defence, thus identifying new molecular components and processes relevant for CWI maintenance.


Assuntos
Arabidopsis/genética , Parede Celular/metabolismo , Genes de Plantas/fisiologia , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Ascomicetos , Parede Celular/fisiologia , Resistência à Doença/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas/genética , Técnicas de Silenciamento de Genes , Interações Hospedeiro-Patógeno , Doenças das Plantas/imunologia , Plântula/metabolismo , Plântula/fisiologia , Espectroscopia de Infravermelho com Transformada de Fourier
2.
Cell Physiol Biochem ; 53(2): 285-300, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31334617

RESUMO

BACKGROUND/AIMS: Although naturally-derived antifungals have been investigated for their ability to inactivate Candida albicans, which is a major cause of candidiasis, they have shown a less than 3 log reduction in C. albicans or required treatment times of longer than 3 h. Thus, the naturally-derived antifungals used in previous studies could not substantially eradicate C. albicans within a short period of time. METHODS: To improve the fungicidal effects of naturallyderived antifungals against C. albicans within short time periods, we developed composites showing antifungal synergism using caprylic acid (CA), carvacrol (CAR) and thymol (THM) for 1-10 min at 22/37°C. Using flow cytometry, we examined the mode of action for the synergism of these compounds on membrane integrity and efflux pump activity. RESULTS: Whereas the maximum reduction by individual treatments was 0.6 log CFU/ml, CA + CAR/THM (all 1.5 mM) eliminated all pathogens (> 6.8 log reduction) after 1 min at 37°C and after 10 min at 22°C. The flow cytometry results showed that exposure to CA damaged the membranes in 15.7-36.5% of cells and inhibited efflux pumps in 15.4-31.3% of cells. Treatments with CAR/THM slightly affected cell membranes (in 1.8-6.9% of cells) but damaged efflux pumps in 14.4-29.6% of cells. However, the combined treatments clearly disrupted membranes (> 83.1% of cells) and pumps (> 95.0% of cells). The mechanism of this synergism may involve membrane damage by CA, which facilitates the entry of antifungals into the cytoplasm, and the inhibition of efflux pumps by CA, CAR or THM, causing their accumulation within cells and, leading to cell death. CONCLUSION: Antifungal composites (CA + CAR/THM) showing synergism (i.e., an additional 6 log reduction) within minutes at room/body temperature can be used to treat candidiasis and improve the microbiological safety of facilities contaminated with fungi as a novel alternative to synthetic antifungals.


Assuntos
Antifúngicos/farmacologia , Candida albicans/efeitos dos fármacos , Caprilatos/farmacologia , Proteínas Fúngicas/metabolismo , Monoterpenos/farmacologia , Timol/farmacologia , Candida albicans/metabolismo , Parede Celular/efeitos dos fármacos , Parede Celular/metabolismo , Sinergismo Farmacológico , Concentração de Íons de Hidrogênio , Testes de Sensibilidade Microbiana , Temperatura Ambiente
3.
Plant Mol Biol ; 101(1-2): 113-127, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31300998

RESUMO

Transcriptional regulation is an essential molecular machinery in controlling gene expression in diverse plant developmental processes including fruit ripening. This involves the interaction of transcription factors (TFs) and promoters of target genes. In banana, although a number of fruit ripening-associated TFs have been characterized, their number is relatively small. Here we identified a nuclear-localized basic leucine zipper (bZIP) TF, MabZIP93, associated with banana ripening. MabZIP93 activated cell wall modifying genes MaPL2, MaPE1, MaXTH23 and MaXGT1 by directly binding to their promoters. Transient over-expression of MabZIP93 in banana fruit resulted in the increased expression of MaPL2, MaPE1, MaXTH23 and MaXGT1. Moreover, a mitogen-activated protein kinase MaMPK2 and MabZIP93 were found to interact with MabZIP93. The interaction of MabZIP93 with MaMPK2 enhanced MabZIP93 activation of cell wall modifying genes, which was likely due to the phosphorylation of MabZIP93 mediated by MaMPK2. Overall, this study shows that MaMPK2 interacts with and phosphorylates MabZIP93 to promote MabZIP93-mediated transcriptional activation of cell wall modifying genes, thereby expanding our understanding of gene networks associated with banana fruit ripening.


Assuntos
Regulação da Expressão Gênica de Plantas , Redes Reguladoras de Genes/genética , Musa/genética , Proteínas de Plantas/metabolismo , Ativação Transcricional , Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Núcleo Celular/metabolismo , Parede Celular/metabolismo , Frutas/genética , Musa/fisiologia , Fosforilação , Proteínas de Plantas/genética , Regiões Promotoras Genéticas/genética
4.
World J Microbiol Biotechnol ; 35(7): 105, 2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31267317

RESUMO

Pseudocercospora fijiensis causes black Sigatoka disease, the most important threat to banana. The cell wall is crucial for fungal biological processes, including pathogenesis. Here, we performed cell wall proteomics analyses of two P. fijiensis strains, the highly virulent Oz2b, and the less virulent C1233 strains. Strains were starved from nitrogen to mimic the host environment. Interestingly, in vitro cultures of the C1233 strain grew faster than Oz2b in PDB medium, suggesting that C1233 survives outside the host better than the highly virulent Oz2b strain. Both strains were submitted to nitrogen starvation and the cell wall proteins were isolated and subjected to nano-HPLC-MS/MS. A total of 2686 proteins were obtained from which only 240 had a known function and thus, bioinformatics analyses were performed on this group. We found that 90 cell wall proteins were shared by both strains, 21 were unique for Oz2b and 39 for C1233. Shared proteins comprised 24 pathogenicity factors, including Avr4 and Ecp6, two effectors from P. fijiensis, while the unique proteins comprised 16 virulence factors in C1233 and 11 in Oz2b. The P. fijiensis cell wall proteome comprised canonical proteins, but thirty percent were atypical, a feature which in other phytopathogens has been interpreted as contamination. However, a comparison with the identities of atypical proteins in other reports suggests that the P. fijiensis proteins we detected were not contaminants. This is the first proteomics analysis of the P. fijiensis cell wall and our results expands the understanding of the fundamental biology of fungal phytopathogens and will help to decipher the molecular mechanisms of pathogenesis and virulence in P. fijiensis.


Assuntos
Ascomicetos/genética , Ascomicetos/metabolismo , Parede Celular/genética , Parede Celular/metabolismo , Proteoma , Fatores de Virulência/genética , Fatores de Virulência/metabolismo , Ascomicetos/isolamento & purificação , Ascomicetos/patogenicidade , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Genes Fúngicos/genética , Genoma Fúngico , Musa/microbiologia , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Espectrometria de Massas em Tandem , Virulência
5.
Food Chem ; 297: 124867, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253333

RESUMO

Broad molecular weight (MW) distribution and variability of mannan to protein ratio of purified mannoproteins (MP), isolated from yeast cell walls upon the enzymatic treatment, revealed their multiplicity. The main fraction of high-MW Agrimos®-MP1 and YCW-b-MP1' contained mannoproteins with a mannan to protein ratio of 3.5 and 6.9, respectively. Low-MW YCW-b-MP2' was mainly comprised of mannan, with a ratio of 181, whereas low-MW Agrimos®-MP2 was characterized by a ratio of 12.2. The solubility of MP1/MP2 was higher than that of MP1'/MP2'. Mannoproteins showed similar or lower solubility than mannan, and they exhibited a Newtonian behaviour. Sonication was the appropriate method for the formation of mannoproteins-based emulsions. Contrary to MP1/MP1'-based emulsions, MP2/MP2'-based ones showed higher affinity towards soybean oil than glyceryl-trioleate. pH affected the emulsifying ability of MP1/MP1'. MP1/MP1' showed similar or slightly inferior emulsifying properties than lecithin. This study is expected to broaden the applications of mannoproteins as value-added ingredients.


Assuntos
Mananas/química , Glicoproteínas de Membrana/química , Saccharomyces cerevisiae/metabolismo , Parede Celular/metabolismo , Concentração de Íons de Hidrogênio , Mananas/metabolismo , Glicoproteínas de Membrana/metabolismo , Peso Molecular , Solubilidade , Temperatura Ambiente , Viscosidade
6.
Ecotoxicol Environ Saf ; 181: 455-462, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31228821

RESUMO

Macleaya cordata is a perennial herb, a candidate phytoremediation plant with high biomass and manganese (Mn) tolerance. To study the mechanism underlying its Mn adaptability, Mn2+ at various concentrations (0, 1000, 5000, 10000, 15000, and 20000 µM) were applied to M. cordata to investigate the subcellular distribution and chemical forms of Mn, as well as the resulting physiological and biochemical changes by pot culture experiment under natural light in a greenhouse. According to our results, Mn level in M. cordata increased with exogenous Mn concentrations; and Mn contents in different tissues exhibited a leaf > root > stem pattern. Meanwhile, biomass and the level of photosynthetic pigments increased at lower Mn concentrations but declined as Mn concentration further ascended. Subcellular distribution analysis revealed that Mn was sequestered in cell wall and vacuole; in addition, it was incorporated into pectates and protein, phosphates, and oxalates. These findings revealed a possible effective strategy for M. cordata to reduce Mn mobility and toxicity. Moreover, a continuous boost in the level of malondialdehyde was observed with Mn gradient; whereas contents of soluble proteins and proline, and the activities of superoxide dismutase and peroxidase were initially increased and then dropped. Altogether, these results indicated that most Mn was trapped in the cell wall and soluble fractions in low toxicity forms such as pectates and protein, phosphates, and oxalates. These strategies, that is functioning cooperatively with the well-coordinated antioxidant defense systems and the non-enzymatic metabolites, confer strong resistance to Mn in M. cordata.


Assuntos
Adaptação Fisiológica , Poluentes Ambientais/metabolismo , Manganês/metabolismo , Papaveraceae/fisiologia , Antioxidantes/metabolismo , Biodegradação Ambiental , Biomassa , Parede Celular/metabolismo , Papaveraceae/enzimologia , Papaveraceae/metabolismo , Fotossíntese , Vacúolos/metabolismo
7.
Plant Physiol Biochem ; 141: 164-171, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31170640

RESUMO

For a comprehensive understanding of gene expression, enzyme activity and sugar concentrations in response to short-term water deficit in apple (Greensleeves), sugar-modulated gene expression and enzyme activities were analyzed. Water stress resulted in the accumulation of sorbitol, glucose, fructose, galactose and starch, accompanied by a significant reduction in photosynthesis and sucrose concentration. In response to short-term water deficits, the activities of aldose-6-phosphate reductase (A6PR; EC 1.1.1.200), sorbitol dehydrogenase (SDH; EC 1.1.1.14), neutral invertase (NINV; EC 3.2.1.26), sucrose synthase (SUSY; EC 2.4.1.13), and fructokinase (FK; EC 2.7.1.4) were higher, whereas cell wall invertase (CWINV; EC 3.2.1.26) and hexokinase (HK; EC 2.7.1.1) activities were lower. In addition, sucrose phosphate synthase (SPS; EC 2.4.1.14) activity increased during the initial stages of dehydration and then decreased as the drought strengthened. Transcript levels of MdA6PR, MdSDH1/2, MdNINV1/2, MdSUSY3, MdFK1/2/4, MdSOT1/2, MdSUC1-3, MdTMT2/3, MdvGT1, MdpGlcT1-4 were upregulated, whereas transcript levels of MdCWINV1/2, MdHK1/2/3/5, and MdTMT1 were downregulated after 6 days of water stress. These findings suggest that the sorbitol metabolism pathway is induced and high levels of hexose derived from photosynthetic products are transported into vacuoles for adjustment to the water deficit. Our results provide insights into the relationships between sugar levels and sugar-modulated gene and enzyme activity in response to the imposition of short-term water stress.


Assuntos
Metabolismo dos Carboidratos/genética , Secas , Regulação da Expressão Gênica de Plantas , Malus/fisiologia , Folhas de Planta/fisiologia , Parede Celular/metabolismo , Frutas/metabolismo , Glucosiltransferases/metabolismo , Malus/genética , Fotossíntese , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/fisiologia , Sorbitol/metabolismo , Estresse Fisiológico , Sacarose/metabolismo , beta-Frutofuranosidase/metabolismo
8.
Plant Mol Biol ; 100(6): 659-674, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31187392

RESUMO

KEY MESSAGE: Oxalotrophic Stenotrophomonas isolated from tomato rhizosphere are able to protect plants against oxalate-producing pathogens by a combination of actions including induction of plant defence signalling callose deposition and the strengthening of plant cell walls and probably the degradation of oxalic acid. Oxalic acid plays a pivotal role in the virulence of the necrotrophic fungi Botrytis cinerea and Sclerotinia sclerotiorum. In this work, we isolated two oxalotrophic strains (OxA and OxB) belonging to the bacterial genus Stenotrophomonas from the rhizosphere of tomato plants. Both strains were capable to colonise endophytically Arabidopsis plants and protect them from the damage caused by high doses of oxalic acid. Furthermore, OxA and OxB protected Arabidopsis from S. sclerotiorum and B. cinerea infections. Bacterial inoculation induced the production of phenolic compounds and the expression of PR-1. Besides, both isolates exerted a protective effect against fungal pathogens in Arabidopsis mutants affected in the synthesis pathway of salicylic acid (sid2-2) and jasmonate perception (coi1). Callose deposition induced by OxA and OxB was required for protection against phytopathogens. Moreover, B. cinerea and S. sclerotiorum mycelial growth was reduced in culture media containing cell wall polysaccharides from leaves inoculated with each bacterial strain. These findings suggest that cell walls from Arabidopsis leaves colonised by these bacteria would be less susceptible to pathogen attack. Our results indicate that these oxalotrophic bacteria can protect plants against oxalate-producing pathogens by a combination of actions and show their potential for use as biological control agents against fungal diseases.


Assuntos
Fungos/patogenicidade , Lycopersicon esculentum/microbiologia , Oxalatos/metabolismo , Stenotrophomonas/fisiologia , Arabidopsis/metabolismo , Botrytis/metabolismo , Botrytis/patogenicidade , Parede Celular/metabolismo , Ciclopentanos/química , Fungos/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Ácido Oxálico/metabolismo , Oxilipinas/química , Filogenia , Doenças das Plantas/microbiologia , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Polissacarídeos/metabolismo , Ácido Salicílico/farmacologia , Transdução de Sinais , Stenotrophomonas/isolamento & purificação
9.
Plant Physiol Biochem ; 141: 456-465, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31247428

RESUMO

Alfalfa (Medicago sativa L.) is an important perennial legume and used as a forage crop worldwide, and has extensive resistance to various abiotic stresses. Nitric oxide (NO) plays a critical role in response to external and internal cues to regulate plant growth and development. However, endogenous NO-mediated molecular mechanisms of drought tolerance in alfalfa is poorly understood. To get a deeper insight into the regulate pathway of NO, RNA-Seq was used to profile transcriptome changes of alfalfa seedlings, which were treated with NO scavenger under normal and drought conditions. A total of 1,025 and 3,461 differently-expressed genes (FDR < 0.0001; fold change ≥ 2) were observed while NO absence under normal and drought conditions, respectively. Based on GO enrich and KEGG pathway analysis, we found NO absence induced photosynthesis, carbon fixation in photosynthetic organisms and primary metabolism were significantly up-enriched. Most oxidoreductase, dehydrogenase, reductase and transferase genes were down-regulated in the above processes. Moreover, NO absence restrained chlorophyll biosynthesis and decreased different sugar content. Therefore, this work provides insights into the mechanism that NO-mediated enhanced photosynthesis and carbohydrate metabolism in alfalfa under drought stress.


Assuntos
Metabolismo dos Carboidratos , Secas , Medicago sativa/enzimologia , Medicago sativa/fisiologia , Óxido Nítrico/química , Fotossíntese , Parede Celular/metabolismo , Clorofila/química , Cloroplastos/metabolismo , Perfilação da Expressão Gênica , Biblioteca Gênica , Plântula/enzimologia , Plântula/fisiologia , Análise de Sequência de RNA , Amido/química , Estresse Fisiológico , Sacarose/química
10.
Subcell Biochem ; 92: 127-168, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31214986

RESUMO

The peptidoglycan sacculus is a net-like polymer that surrounds the cytoplasmic membrane in most bacteria. It is essential to maintain the bacterial cell shape and protect from turgor. The peptidoglycan has a basic composition, common to all bacteria, with species-specific variations that can modify its biophysical properties or the pathogenicity of the bacteria. The synthesis of peptidoglycan starts in the cytoplasm and the precursor lipid II is flipped across the cytoplasmic membrane. The new peptidoglycan strands are synthesised and incorporated into the pre-existing sacculus by the coordinated activities of peptidoglycan synthases and hydrolases. In the model organism Escherichia coli there are two complexes required for the elongation and division. Each of them is regulated by different proteins from both the cytoplasmic and periplasmic sides that ensure the well-coordinated synthesis of new peptidoglycan.


Assuntos
Peptidoglicano , Parede Celular/metabolismo , Escherichia coli/citologia , Escherichia coli/metabolismo , Peptidoglicano/química , Peptidoglicano/metabolismo
11.
Subcell Biochem ; 92: 417-469, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31214994

RESUMO

Actinobacteria is a group of diverse bacteria. Most species in this class of bacteria are filamentous aerobes found in soil, including the genus Streptomyces perhaps best known for their fascinating capabilities of producing antibiotics. These bacteria typically have a Gram-positive cell envelope, comprised of a plasma membrane and a thick peptidoglycan layer. However, there is a notable exception of the Corynebacteriales order, which has evolved a unique type of outer membrane likely as a consequence of convergent evolution. In this chapter, we will focus on the unique cell envelope of this order. This cell envelope features the peptidoglycan layer that is covalently modified by an additional layer of arabinogalactan . Furthermore, the arabinogalactan layer provides the platform for the covalent attachment of mycolic acids , some of the longest natural fatty acids that can contain ~100 carbon atoms per molecule. Mycolic acids are thought to be the main component of the outer membrane, which is composed of many additional lipids including trehalose dimycolate, also known as the cord factor. Importantly, a subset of bacteria in the Corynebacteriales order are pathogens of human and domestic animals, including Mycobacterium tuberculosis. The surface coat of these pathogens are the first point of contact with the host immune system, and we now know a number of host receptors specific to molecular patterns exposed on the pathogen's surface, highlighting the importance of understanding how the cell envelope of Actinobacteria is structured and constructed. This chapter describes the main structural and biosynthetic features of major components found in the actinobacterial cell envelopes and highlights the key differences between them.


Assuntos
Actinobacteria/citologia , Membrana Celular/química , Membrana Celular/metabolismo , Parede Celular/química , Parede Celular/metabolismo , Animais , Humanos , Mycobacterium tuberculosis/patogenicidade , Ácidos Micólicos/metabolismo , Peptidoglicano/metabolismo
12.
Photochem Photobiol Sci ; 18(7): 1700-1708, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31214675

RESUMO

The ever growing world-population poses challenges concerning the need for more food free of pesticide residues. The most common means to control plant pathogens is through the application of pesticides, which raises concerns over safety for humans and the environment. Recently, Photodynamic Inactivation (PDI) of microorganisms using natural photosensitizers has shown itself to be a powerful tool to combat bacteria and fungi. This study investigates the efficacy of PDI against the Gram(+) bacterial plant pathogen Rhodococcus fascians and Gram(-) Xanthomonas axonopodis and Erwinia amylovora using two chlorin e6 derivatives as photosensitizers: anionic sodium magnesium chlorophyllin (Chl, approved as food additive E140) in combination with cell wall permeabilizing agents (Na2EDTA or Polyaspartic acid sodium salt (PA)) and B17-0024, a mixture of chlorin e6 derivatives with cationic moieties at physiological pH. Both photosensitizers show excellent efficacy against R. fascians, whereby B17-0024 is phototoxic at a one order of magnitude lower concentration than Chl (10 µM B17-0024: relative inactivation (r.i.) >7.5 × 106, 100 µM Chl: r.i. 2.2 × 106, illumination with 26.6 J cm-2, 395 nm). The phototreatment of Gram(-) bacteria with Chl requires the obligatory use of cell wall permeabilizing agents like Na2EDTA (X. axonopodis) or PA (E. amylovora) to induce significant killing (more than 7 log units at 100 µM). On the other hand, B17-0024 proves to be a highly effective photosensitizer inducing bacterial inactivation at very low concentrations (10 µM for R. fascians and X. axonopodis, 100 µM for E. amylovora) without additives. In summary, PDI using both the natural photosensitizer Chl in combination with cell wall permeabilizing agents is effective and environmentally friendly. As an alternative, B17-0024 is highly photoactive against all model strains tested - even without cell wall permeabilizing agents. The photodynamic approach based on chlorin e6 derivatives should add to the growers' toolbox as a preferred alternative for the control of phytopathogens.


Assuntos
Produtos Agrícolas/microbiologia , Erwinia amylovora/efeitos da radiação , Luz , Rhodococcus/efeitos da radiação , Xanthomonas axonopodis/efeitos da radiação , Parede Celular/efeitos dos fármacos , Parede Celular/metabolismo , Erwinia amylovora/efeitos dos fármacos , Peptídeos/química , Peptídeos/farmacologia , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/farmacologia , Porfirinas/química , Porfirinas/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Rhodococcus/efeitos dos fármacos , Xanthomonas axonopodis/efeitos dos fármacos
13.
BMC Plant Biol ; 19(1): 262, 2019 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-31208336

RESUMO

BACKGROUND: Stored potato (Solanum tuberosum L.) tubers are sensitive to wet conditions that can cause rotting in long-term storage. To study the effect of water on the tuber surface during storage, microarray analysis, RNA-Seq profiling, qRT-PCR and phytohormone measurements were performed to study gene expression and hormone content in wet tubers incubated at two temperatures: 4 °C and 15 °C. The growth of the plants was also observed in a greenhouse after the incubation of tubers in wet conditions. RESULTS: Wet conditions induced a low-oxygen response, suggesting reduced oxygen availability in wet tubers at both temperatures when compared to that in the corresponding dry samples. Wet conditions induced genes coding for heat shock proteins, as well as proteins involved in fermentative energy production and defense against reactive oxygen species (ROS), which are transcripts that have been previously associated with low-oxygen stress in hypoxic or anoxic conditions. Wet treatment also induced senescence-related gene expression and genes involved in cell wall loosening, but downregulated genes encoding protease inhibitors and proteins involved in chloroplast functions and in the biosynthesis of secondary metabolites. Many genes involved in the production of phytohormones and signaling were also affected by wet conditions, suggesting altered regulation of growth by wet conditions. Hormone measurements after incubation showed increased salicylic acid (SA), abscisic acid (ABA) and auxin (IAA) concentrations as well as reduced production of jasmonate 12-oxo-phytodienoic acid (OPDA) in wet tubers. After incubation in wet conditions, the tubers produced fewer stems and more roots compared to controls incubated in dry conditions. CONCLUSIONS: In wet conditions, tubers invest in ROS protection and defense against the abiotic stress caused by reduced oxygen due to excessive water. Changes in ABA, SA and IAA that are antagonistic to jasmonates affect growth and defenses, causing induction of root growth and rendering tubers susceptible to necrotrophic pathogens. Water on the tuber surface may function as a signal for growth, similar to germination of seeds.


Assuntos
Armazenamento de Alimentos , Reguladores de Crescimento de Planta/metabolismo , Tubérculos/metabolismo , Solanum tuberosum/metabolismo , Metabolismo dos Carboidratos , Parede Celular/metabolismo , Cloroplastos/metabolismo , Regulação da Expressão Gênica de Plantas , Análise de Sequência com Séries de Oligonucleotídeos , Estresse Oxidativo , Tubérculos/crescimento & desenvolvimento , Metabolismo Secundário , Solanum tuberosum/crescimento & desenvolvimento , Transcriptoma , Água
14.
Nat Commun ; 10(1): 2647, 2019 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-31201321

RESUMO

Growth and division by most bacteria requires remodelling and cleavage of their cell wall. A byproduct of this process is the generation of free peptidoglycan (PG) fragments known as muropeptides, which are recycled in many model organisms. Bacteria and hosts can harness the unique nature of muropeptides as a signal for cell wall damage and infection, respectively. Despite this critical role for muropeptides, it has long been thought that pathogenic mycobacteria such as Mycobacterium tuberculosis do not recycle their PG. Herein we show that M. tuberculosis and Mycobacterium bovis BCG are able to recycle components of their PG. We demonstrate that the core mycobacterial gene lpqI, encodes an authentic NagZ ß-N-acetylglucosaminidase and that it is essential for PG-derived amino sugar recycling via an unusual pathway. Together these data provide a critical first step in understanding how mycobacteria recycle their peptidoglycan.


Assuntos
Acetilglucosaminidase/metabolismo , Proteínas de Bactérias/metabolismo , Mycobacterium bovis/metabolismo , Mycobacterium tuberculosis/metabolismo , Peptidoglicano/metabolismo , Antibióticos Antituberculose/farmacologia , Parede Celular/química , Parede Celular/metabolismo , Farmacorresistência Bacteriana , Testes de Sensibilidade Microbiana , Ácidos Murâmicos/metabolismo , Muramidase/farmacologia , Mycobacterium bovis/química , Mycobacterium tuberculosis/química , Peptidoglicano/química
15.
Nat Commun ; 10(1): 2733, 2019 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-31227716

RESUMO

Cell wall antibiotics are crucial for combatting the emerging wave of resistant bacteria. Yet, our understanding of antibiotic action is limited, as many strains devoid of all resistance determinants display far higher antibiotic tolerance in vivo than suggested by the antibiotic-target binding affinity in vitro. To resolve this conflict, here we develop a comprehensive theory for the bacterial cell wall biosynthetic pathway and study its perturbation by antibiotics. We find that the closed-loop architecture of the lipid II cycle of wall biosynthesis features a highly asymmetric distribution of pathway intermediates, and show that antibiotic tolerance scales inversely with the abundance of the targeted pathway intermediate. We formalize this principle of minimal target exposure as intrinsic resistance mechanism and predict how cooperative drug-target interactions can mitigate resistance. The theory accurately predicts the in vivo efficacy for various cell wall antibiotics in different Gram-positive bacteria and contributes to a systems-level understanding of antibiotic action.


Assuntos
Vias Biossintéticas/efeitos dos fármacos , Parede Celular/efeitos dos fármacos , Farmacorresistência Bacteriana/efeitos dos fármacos , Bactérias Gram-Positivas/metabolismo , Infecções por Bactérias Gram-Positivas/tratamento farmacológico , Parede Celular/metabolismo , Bactérias Gram-Positivas/efeitos dos fármacos , Infecções por Bactérias Gram-Positivas/microbiologia , Modelos Biológicos , Uridina Difosfato Ácido N-Acetilmurâmico/análogos & derivados , Uridina Difosfato Ácido N-Acetilmurâmico/biossíntese
16.
Plant Sci ; 285: 132-140, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31203877

RESUMO

Xanthomonas campestris pv. campestris (Xcc)- responsive soluble and cell wall-bound hydroxycinnamic acids (HAs) and flavonoids accumulation in relation to hormonal changes in two Brassica napus cultivars contrasting disease susceptibility were interpreted with regard to the disease resistance. At 14-day post inoculation with Xcc, disease resistance in cv. Capitol was distinguished by an accumulation of specific (HAs) and flavonoids particularly in cell-wall bound form, and was characterized by higher endogenous jasmonic acid (JA) resulting in a decrease of JA-based balance with other hormones, as well as enhanced expression of JA signaling that was concurrently based on upregulation of PAP1 (production of anthocyanin pigment 1), MYB transcription factor, and phenylpropanoid biosynthetic genes. Fourier transform infrared spectra confirmed higher amounts of esterified phenolic acids in cv. Capitol. These results indicate that enhanced JA levels and signaling in resistant cultivar was associated with a higher accumulation of HAs and flavonoids, particularly in the cell wall-bound form, and vice versa in the susceptible cultivar (cv. Mosa) with enhanced SA-, ABA-, and CK- levels and signaling. Thus the JA-mediated phenolic metabolites accumulation is an important feature for the management and breeding program to develop disease-resistant B. napus cultivar.


Assuntos
Brassica napus/imunologia , Parede Celular/metabolismo , Ácidos Cumáricos/metabolismo , Ciclopentanos/metabolismo , Resistência à Doença , Oxilipinas/metabolismo , Fenóis/metabolismo , Reguladores de Crescimento de Planta/fisiologia , Xanthomonas campestris , Brassica napus/metabolismo , Brassica napus/microbiologia , Brassica napus/fisiologia , Parede Celular/fisiologia , Resistência à Doença/fisiologia , Suscetibilidade a Doenças/microbiologia , Suscetibilidade a Doenças/fisiopatologia , Flavonoides/metabolismo , Peroxidação de Lipídeos , Microscopia Eletrônica de Varredura , Peptídeo Hidrolases/metabolismo , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Reguladores de Crescimento de Planta/metabolismo , Folhas de Planta/microbiologia , Folhas de Planta/ultraestrutura , Espécies Reativas de Oxigênio/metabolismo
17.
Plant Sci ; 285: 141-150, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31203879

RESUMO

Plant tissue brittleness is related to cellular structure and lodging. MED0031 is a mutant identified previously from ethyl methane sulfonate treatment of diploid wheat accession TA2726, showing brittleness in both stem and leaf. In microscopic and histological observations, the mutant was found to have less large vascular bundles per unit area, a thinner sclerenchyma cell wall, and a broader parenchyma, compared with the wild type. The mutated gene, TmBr1, was mapped to a 0.056 cM interval on chromosome 5Am. This gene was cloned using a MapRseq approach that searched the candidate gene through combination of the prior target gene mapping information with SNP calling and discovery of differentially expressed genes from RNA_seq data of the wild type and a BC3F2 bulk showing the mutant phenotype. TmBr1 encodes a COBL protein and a nonsense mutation within the region coding for the conserved COBRA domain caused premature translation termination. Introduction of TmBr1 to Arabidopsis AtCOBL4 mutant rescued the phenotype, demonstrating their functional conservation. Apart from the effect on cellulose content, the TmBr1 mutation might modulate synthesis of noncellulosic polysaccharide pectin as well. Application of the MapRseq approach to isolation of genes present in recombination cold spots and complicated genomes was discussed.


Assuntos
Clonagem Molecular/métodos , Genes de Plantas/genética , Triticum/genética , Parede Celular/metabolismo , Celulose/metabolismo , Mapeamento Cromossômico , Genes de Plantas/fisiologia , Lignina/metabolismo , Microscopia Eletrônica de Varredura , Pectinas/metabolismo , Filogenia , Reação em Cadeia da Polimerase em Tempo Real , Triticum/anatomia & histologia , Triticum/fisiologia
18.
J Agric Food Chem ; 67(27): 7561-7568, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31246021

RESUMO

The development of botanical applications of nanomaterials has produced a new generation of technologies that can profoundly impact botanical research. Semiconductor quantum dots (QDs) are an archetype nanomaterial and have received significant interest from diverse research communities, owing to their unique and optimizable optical properties. In this review, we describe the most recent progress on QD-based botanical research and discuss the uptake, translocation, and effects of QDs on plants and the potential applications of QDs in botany. A critical evaluation of the current limitations of QD technologies is discussed, along with the future prospects in QD-based botanical research.


Assuntos
Botânica/tendências , Pontos Quânticos , Semicondutores/tendências , Parede Celular/metabolismo , Hidroponia , Células Vegetais/metabolismo , Células Vegetais/ultraestrutura , Desenvolvimento Vegetal , Fenômenos Fisiológicos Vegetais , Plantas/genética , Plantas/metabolismo , Solo
19.
J Microbiol ; 57(9): 725-731, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31124044

RESUMO

A Gram-staining-positive, motile and short-rod-shaped actinobacterium designated 9W16Y-2T was isolated from surface-sterilized leaves of reed (Phragmites australis) collected from Taklamakan Desert in Xinjiang Uygur Autonomous Region, China. Colonies were pale greenish yellow, circular, smooth, and convex. The 16S rRNA gene sequence of strain 9W16Y-2T exhibited highest sequence similarities with Aeromicrobium camelliae CGMCC 1.12942T (99.0%) and Aeromicrobium erythreum NRRL B-3381T (97.2%). Phylogenetic analyses based on 16S rRNA gene sequences and single-copy phylogenetic marker genes (pMGs) showed that strain 9W16Y-2T belonged to the genus Aeromicrobium and formed a monophyletic clade with Aeromicrobium camelliae CGMCC 1.12942T. Furthermore, average nucleotide identity (ANI) and DNA-DNA hybridization (DDH) clearly separated strain 9W16Y-2T from the other species of the genus Aeromicrobium with values below the thresholds for species delineation. The G+C content of the genomic DNA is 68.9 mol%. The diagnostic diamino acid of the cell-wall peptidoglycan was LL-diaminopimelic acid. The predominant menaquinone was MK-9(H4). The major fatty acids (> 10% of the total fatty acids) were C18:0 10-methyl (TBSA) (28.2%), C16:0 (21.0%), C16:0 2-OH (20.8%) and C18:1ω9c (12.8%). The polar lipid profile comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylinositol, an unidentified aminophospholipid and an unidentified lipid. Based on the phylogenic, phenotypic and chemotaxonomic features, strain 9W16Y-2T represents a novel species of the genus Aeromicrobium, for which the name Aeromicrobium endophyticum sp. nov. is proposed. The type strain is 9W16Y-2T (= CGMCC 1.13876T = JCM 33141T).


Assuntos
Actinobacteria/isolamento & purificação , Endófitos/isolamento & purificação , Poaceae/microbiologia , Actinobacteria/classificação , Actinobacteria/genética , Actinobacteria/metabolismo , Técnicas de Tipagem Bacteriana , Parede Celular/química , Parede Celular/metabolismo , China , DNA Bacteriano/genética , Endófitos/classificação , Endófitos/genética , Endófitos/metabolismo , Ácidos Graxos/química , Ácidos Graxos/metabolismo , Peptidoglicano/química , Peptidoglicano/metabolismo , Filogenia , RNA Ribossômico 16S/genética
20.
Carbohydr Polym ; 217: 126-134, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31079668

RESUMO

Longan pulp is an excellent source of polysaccharides and other nutrients that have many health benefits. However, longans is susceptible to pulp breakdown after harvest and loses its nutrition values. To solve this problem, this study aimed to study the effects of a novel chitosan, Kadozan, on pulp breakdown index, contents of pectin, cellulose and hemicelluloses, and activities of enzymes in longan pulp relating to disassembly of polysaccharides (XET, PE, PG, ß-Gal, and cellulase). The data illustrated that, compared to the control longans, chitosan-treated longans contained higher amounts of CWM, CSP, ISP, cellulose and hemicelluloses, but exhibited lower pulp breakdown index, lower activities of cell wall-disassembling enzymes, and contained lower WSP amount. These results suggested that Kadozan with a dilution of 1:500 (VKadozan: VKadozan + Water) could significantly decrease activities of disassembling-enzymes and depolymerization of polysaccharides in cell wall, and subsequently alleviate pulp breakdown and prolong storage-life of postharvest longans.


Assuntos
Parede Celular/efeitos dos fármacos , Quitosana/farmacologia , Inibidores Enzimáticos/farmacologia , Frutas/metabolismo , Polissacarídeos/metabolismo , Sapindaceae/metabolismo , Parede Celular/metabolismo , Celulose/metabolismo , Conservação de Alimentos/métodos , Qualidade dos Alimentos , Glicosídeo Hidrolases/antagonistas & inibidores , Hidrólise/efeitos dos fármacos , Pectinas/metabolismo
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