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1.
Plant Mol Biol ; 102(4-5): 431-445, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31907707

RESUMO

KEY MESSAGE: Iron deficiency conditions as well as iron supplied as a Fe(III)-mimosine complex induced a number of strategy I and strategy II genes for iron uptake in leucaena. Leucaena leucocephala (leucaena) is a tree-legume that can grow in alkaline soils, where metal-cofactors like Fe(III) are sparingly available. Mimosine, a known chelator of Fe(III), may facilitate Fe(III) uptake in leucaena by serving as a phytosiderophore. To test if mimosine can serve as a phytosiderophore, three sets of experiments were carried out. First, the binding properties and solubility of metal-mimosine complexes were assessed through spectrophotometry. Second, to study mimosine uptake in plants, pole bean, common bean, and tomato plants were supplied with mimosine alone and metal-mimosine complexes. Third, the expression of strategy I (S1) and strategy II (S2) genes for iron uptake from the soil was studied in leucaena plants exposed to different Fe(III) complexes. The results of this study show that (i) mimosine has high binding affinity for metallic cations at alkaline pH, Fe(III)-mimosine complexes are water soluble at alkaline pH, and that mimosine can bind soil iron under alkaline pH; (ii) pole bean, common bean, and tomato plants can uptake mimosine and transport it throughout the plant; and (iii) a number of S1 and S2 genes were upregulated in leucaena under iron-deficiency condition or when Fe(III) was supplied as a Fe(III)-mimosine complex. These findings suggest that leucaena may utilize both S1 and S2 strategies for iron uptake; and mimosine may play an important role in both strategies.


Assuntos
Fabaceae/efeitos dos fármacos , Fabaceae/metabolismo , Mimosina/farmacocinética , Transporte Biológico , Tampões (Química) , Cátions , Compostos Férricos/metabolismo , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Ferro/metabolismo , Metais/metabolismo , Nitrogênio , Phaseolus/efeitos dos fármacos , Phaseolus/metabolismo , Folhas de Planta/metabolismo , Caules de Planta/metabolismo , Ligação Proteica , Sideróforos/metabolismo , Solo , Solanum/efeitos dos fármacos , Solanum/metabolismo , Solubilidade
2.
World J Microbiol Biotechnol ; 36(2): 26, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31997078

RESUMO

Salinity stress is one of the key constraints for sustainable crop production. It has gained immense importance in the backdrop of climate change induced imbalanced terrestrial water budgets. The traditional agronomic approaches and breeding salt-tolerant genotypes have often proved insufficient to alleviate salinity stress. Newer approaches like the use of bacterial endophytes associated with agricultural crops have occupied center place recently, owing to their advantageous role in improving crop growth, health and yield. Research evidences have revealed that bacterial endophytes can promote plant growth by accelerating availability of mineral nutrients, helping in production of phytohormones, siderophores, and enzymes, and also by activating systemic resistance against insect pest and pathogens in plants. These research developments have opened an innovative boulevard in agriculture for capitalizing bacterial endophytes, single species or consortium, to enhance plant salt tolerance capabilities, and ultimately lead to translational refinement of crop-production business under salty environments. This article reviews the latest research progress on the identification and functional characterization of salt tolerant endophytic bacteria and illustrates various mechanisms triggered by them for plant growth promotion under saline environment.


Assuntos
Bactérias/metabolismo , Endófitos/fisiologia , Desenvolvimento Vegetal/fisiologia , Tolerância ao Sal/fisiologia , Plantas Tolerantes a Sal/microbiologia , Produtos Agrícolas/metabolismo , Produtos Agrícolas/microbiologia , Microbiota , Reguladores de Crescimento de Planta/metabolismo , Raízes de Plantas/microbiologia , Salinidade , Sideróforos/metabolismo , Microbiologia do Solo
3.
J Appl Microbiol ; 128(1): 265-279, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31574191

RESUMO

AIMS: Many physiological and microbial characteristics influence the biocontrol performance of the biological control agents (BCAs) in agricultural fields. To implement effective biocontrol, the contribution of specific genes, mechanisms and traits to the biocontrol performance of BCAs need to be characterized and explored in greater detail. METHODS AND RESULTS: In this study, a transposon (Tn) mutant library using the BCA Pseudomonas fluorescens NBC275 (Pf275) was generated to explore genes and bacterial characteristics involved in antifungal activity and biocontrol performance. Among the Tn mutants, 205 strains showing variations in antifungal activity compared to wild-type (WT) were selected and further analysed for biocontrol efficacy against gray mold in pepper fruits. The genes involved in pyoverdine biosynthesis (pvdI and pvdD) and chitin-binding protein (gbpA) played essential roles in the antifungal activity and biocontrol capacity of Pf275. In addition, a mutation in phlD completely abolished the antifungal activity and significantly suppressed the biocontrol ability of the strain. Genes affecting antifungal activity of Pf275 significantly influenced swimming motility, which was identified as an important trait for the biocontrol ability of the bacterial strain. CONCLUSIONS: Overall, our results suggest that antifungal compound production, siderophore biosynthesis and swimming motility synergistically contribute to Pf275 biocontrol performance. The utility of this library was demonstrated by identifying genes for antagonism and biocontrol ability in this BCA strain. The functional roles of many genes identified as contributing to antagonism and in vivo biocontrol activity require further study. SIGNIFICANCE AND IMPACT OF THIS STUDY: Genes contributing to antifungal activity and biocontrol performance of P. fluorescens were identified and highlighted by Tn mutagenesis, which will give insight to improve the biocontrol performance of this BCA.


Assuntos
Antibiose/genética , Agentes de Controle Biológico , Genes Bacterianos , Pseudomonas fluorescens/genética , Antifúngicos/metabolismo , Agentes de Controle Biológico/metabolismo , Fungos/metabolismo , Locomoção/genética , Mutação , Doenças das Plantas/microbiologia , Sideróforos/genética , Sideróforos/metabolismo
4.
Microbiol Res ; 232: 126394, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31865222

RESUMO

Extreme ecosystems are a possible source of new interesting microorganisms, in this study the isolation of psychrophilic and psychrotolerant plant growth promoting microorganisms was pursued in a cold habitat, with the aim of finding novel microbes that can protect crops from cold. Eight yeast and four bacterial strains were isolated from rhizospheric soil collected from the Xinantécatl volcano in Mexico, and characterized for plant growth promoting properties. Most of the yeasts produced indole acetic acid and hydrolytic enzymes (cellulases, xilanases and chitinases), but none of them produced siderophores, in contrast to their bacterial counterparts. Inorganic phosphate solubilization was detected for all the bacterial strains and for two yeast strains. Yeast and bacterial strains may inhibit growth of various pathogenic fungi, propounding a role in biological control. Microorganisms were identified up to genera level, by applying ribotyping techniques and phylogenetic analysis. Bacterial strains belonged to the genus Pseudomonas, whereas yeast strains consisted of Rhodotorula sp. (4), Mrakia sp. (3) and Naganishia sp. (1). New species belonging to the aforementioned genera seem to have been isolated from both bacteria and yeasts. Germination promoting activity on Solanum lycopersicum seeds was detected for all strains compared to a control, whereas tomato plantlets, grown at 15 °C in the presence of some of the strains, performed better than the non-inoculated plantlets. This study offers the possibility of using these strains as an additive to improve culture conditions of S. lycopersicum in a more environmentally compatible way. This is the first study to propose psychrophilic/psychrotolerant yeasts, as plant growth promoting microbes.


Assuntos
Bactérias/classificação , Bactérias/isolamento & purificação , Fenômenos Fisiológicos Bacterianos , Filogenia , Desenvolvimento Vegetal , Leveduras/classificação , Leveduras/isolamento & purificação , Altitude , Temperatura Baixa , DNA/isolamento & purificação , Ecossistema , Fungos/patogenicidade , Germinação , Ácidos Indolacéticos/metabolismo , Lycopersicon esculentum/crescimento & desenvolvimento , México , Doenças das Plantas , Rizosfera , Sementes/crescimento & desenvolvimento , Sideróforos/metabolismo , Microbiologia do Solo , Estresse Fisiológico , Erupções Vulcânicas , Leveduras/fisiologia
5.
Sheng Wu Gong Cheng Xue Bao ; 35(11): 2189-2200, 2019 Nov 25.
Artigo em Chinês | MEDLINE | ID: mdl-31814364

RESUMO

Siderophore is a chelating iron substance secreted by microorganisms at low intracellular iron concentration. Siderophore can be divided into three categories: catechol salts, hydroxamic salts and carboxylates. The transport of siderophore is regulated by Fur, σ factor and quorum sensing signal. In recent years, siderophore has been used in fields such as oil pollution remediation, heavy metal pollution remediation and pulp biological bleaching, and has received extensive attention. This paper reviews the classification of siderophores and their transport regulation mechanism, and the application of siderophore in environmental pollution control and remediation. Furthermore, we address the application of siderophore in the future.


Assuntos
Recuperação e Remediação Ambiental , Sideróforos , Transporte Biológico , Sideróforos/classificação , Sideróforos/metabolismo
6.
Res Microbiol ; 170(8): 345-357, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31678562

RESUMO

Iron acquisition is an essential aspect of cell physiology for most bacteria. Although much is known about how bacteria initially recognize the various iron sources they can encounter, whether siderophore, heme, host iron/heme binding proteins, much less is known about how the iron containing compounds (Fe2+, Fe3+, Fe3+-siderophore complex or heme) are transported across the cytoplasmic membrane. This last transport step is powered by specific ABC (ATP-Binding-Cassette) transporters, made up of a substrate binding protein (SBP) that delivers its cargo to the TMD (TransMembrane Domain) of the ABC transporter triggering the entry of the substrate inside the cytoplasm upon catalytic activity of the ABC module. This review focuses on structural aspects of the functioning of such ABC transporters with the most part devoted to the substrate binding proteins.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Bactérias/metabolismo , Compostos de Ferro/metabolismo , Transporte Biológico/fisiologia , Membrana Celular/metabolismo , Heme/metabolismo , Modelos Moleculares , Sideróforos/metabolismo
7.
Infect Immun ; 87(12)2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31570563

RESUMO

Bacteria use siderophores to scavenge iron from environmental or host sources. The iron acquisition systems of Chromobacterium violaceum, a ubiquitous environmental bacterium that can cause infections in humans, are still unknown. In this work, we demonstrated that C. violaceum produces putative distinct endogenous siderophores, here named chromobactin and viobactin, and showed that they are each required for iron uptake and virulence. An in silico analysis in the genome of C. violaceum revealed that genes related to synthesis and uptake of chromobactin (cba) and viobactin (vba) are located within two secondary-metabolite biosynthetic gene clusters. Using a combination of gene deletions and siderophore detection assays, we revealed that chromobactin and viobactin are catecholate siderophores synthesized from the common precursor 2,3-dihydroxybenzoate (2,3-DHB) on two nonribosomal peptide synthetase (NRPS) enzymes (CbaF and VbaF) and taken up by two TonB-dependent receptors (CbuA and VbuA). Infection assays in mice revealed that both the synthesis and the uptake of chromobactin or viobactin are required for the virulence of C. violaceum, since only the mutant strains that do not produce any siderophores or are unable to take up both of them were attenuated for virulence. In addition, the mutant strain unable to take up both siderophores showed a pronounced attenuation of virulence in vivo and reduced neutrophil extracellular trap (NET) formation in in vitro assays, suggesting that extracellularly accumulated siderophores modulate the host immune response. Overall, our results revealed that C. violaceum uses distinct endogenous siderophores for iron uptake and its establishment in the host.


Assuntos
Chromobacterium/genética , Chromobacterium/metabolismo , Ferro/metabolismo , Sideróforos/genética , Sideróforos/metabolismo , Animais , Transporte Biológico/fisiologia , Chromobacterium/patogenicidade , Armadilhas Extracelulares/metabolismo , Feminino , Hidroxibenzoatos/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Família Multigênica/genética , Neutrófilos/metabolismo , Peptídeo Sintases/metabolismo
8.
Nat Commun ; 10(1): 4853, 2019 10 24.
Artigo em Inglês | MEDLINE | ID: mdl-31649262

RESUMO

Few secreted proteins involved in plant infection common to necrotrophic bacteria, fungi and oomycetes have been identified except for plant cell wall-degrading enzymes. Here we study a family of iron-binding proteins that is present in Gram-negative and Gram-positive bacteria, fungi, oomycetes and some animals. Homolog proteins in the phytopathogenic bacterium Dickeya dadantii (IbpS) and the fungal necrotroph Botrytis cinerea (BcIbp) are involved in plant infection. IbpS is secreted, can bind iron and copper, and protects the bacteria against H2O2-induced death. Its 1.7 Å crystal structure reveals a classical Venus Fly trap fold that forms dimers in solution and in the crystal. We propose that secreted Ibp proteins binds exogenous metals and thus limit intracellular metal accumulation and ROS formation in the microorganisms.


Assuntos
Arabidopsis/metabolismo , Cobre/metabolismo , Proteínas de Ligação ao Ferro/metabolismo , Ferro/metabolismo , Doenças das Plantas/microbiologia , Espécies Reativas de Oxigênio/metabolismo , Anti-Infecciosos Locais/farmacologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Botrytis/genética , Botrytis/metabolismo , Proteínas de Transporte/metabolismo , Defensinas/genética , Dimerização , Gammaproteobacteria/efeitos dos fármacos , Gammaproteobacteria/genética , Gammaproteobacteria/metabolismo , Peróxido de Hidrogênio/farmacologia , Proteínas de Ligação ao Ferro/genética , Doenças das Plantas/genética , Sideróforos/genética , Sideróforos/metabolismo
9.
Microbes Environ ; 34(4): 347-355, 2019 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-31527341

RESUMO

To develop biofertilizers for rice in Afghanistan, 98 plant growth-promoting rhizobacteria were isolated from rice plants and their morphological and physiological characteristics, such as indole-3-acetic acid production, acetylene reduction, phosphate and potassium solubilization, and siderophore production, were evaluated. The genetic diversity of these bacteria was also analyzed based on 16S rRNA gene sequences. Of 98 bacteria, 89.7% produced IAA, 54.0% exhibited nitrogenase activity, and 40% showed phosphate solubilization and siderophore production. Some isolates assigned to Pseudomonas (brassicacearum, chengduensis, plecoglossicida, resinovorans, and straminea) formed a relationship with rice, and P. resinovorans and P. straminea showed nitrogen fixation. Rhizobium borbori and R. rosettiformans showed a relationship with rice plants and nitrogen fixation. Among the isolates examined, AF134 and AF137 belonging to Enterobacter ludwigii and P. putida produced large amounts of IAA (92.3 µg mL-1) and exhibited high nitrogenase activity (647.4 nmol C2H4 h-1), respectively. In the plant growth test, more than 70% of the inoculated isolates showed significantly increased root and shoot dry weights. Highly diverse bacterial isolates showing promising rice growth-promoting traits were obtained from Afghanistan alkaline soils.


Assuntos
Bactérias/isolamento & purificação , Oryza/microbiologia , Afeganistão , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Ácidos Indolacéticos/metabolismo , Fixação de Nitrogênio , Nitrogenase/metabolismo , Oryza/classificação , Oryza/crescimento & desenvolvimento , Fosfatos/metabolismo , Filogenia , Raízes de Plantas/classificação , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Potássio/metabolismo , RNA Ribossômico 16S/genética , Sideróforos/metabolismo , Microbiologia do Solo
10.
PLoS Pathog ; 15(9): e1007791, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31545842

RESUMO

Iron homeostasis is important for growth, reproduction and other metabolic processes in all eukaryotes. However, the functions of ATP-binding cassette (ABC) transporters in iron homeostasis are largely unknown. Here, we found that one ABC transporter (named FgAtm1) is involved in regulating iron homeostasis, by screening sensitivity to iron stress for 60 ABC transporter mutants of Fusarium graminearum, a devastating fungal pathogen of small grain cereal crops worldwide. The lack of FgAtm1 reduces the activity of cytosolic Fe-S proteins nitrite reductase and xanthine dehydrogenase, which causes high expression of FgHapX via activating transcription factor FgAreA. FgHapX represses transcription of genes for iron-consuming proteins directly but activates genes for iron acquisition proteins by suppressing another iron regulator FgSreA. In addition, the transcriptional activity of FgHapX is regulated by the monothiol glutaredoxin FgGrx4. Furthermore, the phosphorylation of FgHapX, mediated by the Ser/Thr kinase FgYak1, is required for its functions in iron homeostasis. Taken together, this study uncovers a novel regulatory mechanism of iron homeostasis mediated by an ABC transporter in an important pathogenic fungus.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Proteínas Fúngicas/metabolismo , Fusarium/metabolismo , Fusarium/patogenicidade , Ferro/metabolismo , Transportadores de Cassetes de Ligação de ATP/genética , Sequência de Bases , DNA Fúngico/genética , Grão Comestível/microbiologia , Proteínas Fúngicas/genética , Fusarium/genética , Deleção de Genes , Genes Fúngicos , Homeostase , Proteínas com Ferro-Enxofre/genética , Proteínas com Ferro-Enxofre/metabolismo , Modelos Biológicos , Mutação , Doenças das Plantas/microbiologia , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Sideróforos/genética , Sideróforos/metabolismo , Estresse Fisiológico
11.
Cell Mol Biol (Noisy-le-grand) ; 65(6): 22-27, 2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31472044

RESUMO

Salinity is one of the main obstacles to the production of crops in dry regions of the world. This study focuses on the effects of different strains of plant growth promoting rhizobacteria (PGPR) isolated from native soils on the physiological responses of wheat and barley plants under normal and salt stress conditions. Soil samples were collected from a field in Ilam province, in Iran and bacterial isolates were isolated and screened for salt tolerance, included siderophore and ACC-deaminase production and phosphate solubilizing. Thereafter a two-years greenhouse experiment was conducted as a completely randomized block design with four replications. The applied treatments included bacterial inoculation at five levels (B0: non-inoculation, B1: Siderophore producing + salt-tolerant bacteria, B2: phosphate solubilizing + salt-tolerant bacteria, B3: ACC-deaminase producing + salt-tolerant bacteria, B4: Barvar-2 biological fertilizer, B5: Biofarm-2 biological fertilizer) and salt stress at three levels (S1: 0 dS/m, S2: 4 dS/m, S3: 8 dS/m). Results showed that phosphate solubilizing+ salt-tolerant bacteria resulted in the highest barley grain yield at 4 dS/m salinity level and had no significant difference with ACC-deaminase producing + salt-tolerant bacteria and Barvar-2 biological fertilizer and Biofarm-2 biological fertilizer. The highest proline content in wheat and barley observed in Siderophore producing+ salt-tolerant bacteria at 8 dS/m by 17.48 and 23.42, respectively, followed by phosphate solubilizing+ salt-tolerant bacteria by 16.53 and 19.78. Therefore, the application of isolated growth promoting bacteria can be recommended as an effective biofertilizer in Ilam province.


Assuntos
Produção Agrícola/métodos , Fertilizantes , Hordeum/crescimento & desenvolvimento , Rhizobiaceae/metabolismo , Estresse Salino , Triticum/crescimento & desenvolvimento , Análise de Variância , Carbono-Carbono Liases/metabolismo , Hordeum/química , Irã (Geográfico) , Fosfatos/metabolismo , Raízes de Plantas/microbiologia , Prolina/análise , Salinidade , Tolerância ao Sal , Sideróforos/metabolismo , Microbiologia do Solo , Triticum/química
12.
Nat Commun ; 10(1): 3673, 2019 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-31413254

RESUMO

Bacteria use small molecules called siderophores to scavenge iron. Siderophore-Fe3+ complexes are recognised by outer-membrane transporters and imported into the periplasm in a process dependent on the inner-membrane protein TonB. The siderophore enterobactin is secreted by members of the family Enterobacteriaceae, but many other bacteria including Pseudomonas species can use it. Here, we show that the Pseudomonas transporter PfeA recognises enterobactin using extracellular loops distant from the pore. The relevance of this site is supported by in vivo and in vitro analyses. We suggest there is a second binding site deeper inside the structure and propose that correlated changes in hydrogen bonds link binding-induced structural re-arrangements to the structural adjustment of the periplasmic TonB-binding motif.


Assuntos
Proteínas da Membrana Bacteriana Externa/metabolismo , Proteínas de Transporte/metabolismo , Enterobactina/metabolismo , Ferro/metabolismo , Pseudomonas aeruginosa/metabolismo , Receptores de Superfície Celular/metabolismo , Proteínas da Membrana Bacteriana Externa/química , Proteínas de Bactérias , Sítios de Ligação , Proteínas de Transporte/química , Cristalização , Cristalografia por Raios X , Enterobactina/química , Escherichia coli , Técnicas In Vitro , Radioisótopos de Ferro , Proteínas de Membrana , Receptores de Superfície Celular/química , Sideróforos/química , Sideróforos/metabolismo
13.
Cell Host Microbe ; 26(3): 426-434.e6, 2019 09 11.
Artigo em Inglês | MEDLINE | ID: mdl-31447308

RESUMO

Salmonella enterica serovar Typhi causes typhoid fever only in humans. Murine infection with S. Typhimurium is used as a typhoid model, but its relevance to human typhoid is limited. Non-obese diabetic-scid IL2rγnull mice engrafted with human hematopoietic stem cells (hu-SRC-SCID) are susceptible to lethal S. Typhi infection. In this study, we use a high-density S. Typhi transposon library in hu-SRC-SCID mice to identify virulence loci using transposon-directed insertion site sequencing (TraDIS). Vi capsule, lipopolysaccharide (LPS), and aromatic amino acid biosynthesis were essential for virulence, along with the siderophore salmochelin. However, in contrast to the murine S. Typhimurium model, neither the PhoPQ two-component system nor the SPI-2 pathogenicity island was required for lethal S. Typhi infection, nor was the CdtB typhoid toxin. These observations highlight major differences in the pathogenesis of typhoid and non-typhoidal Salmonella infections and demonstrate the utility of humanized mice for understanding the pathogenesis of a human-specific pathogen.


Assuntos
Estudo de Associação Genômica Ampla/métodos , Infecções por Salmonella/metabolismo , Infecções por Salmonella/microbiologia , Salmonella typhi/genética , Salmonella typhi/patogenicidade , Aminoácidos Aromáticos/biossíntese , Animais , Proteínas de Bactérias/genética , Toxinas Bacterianas/genética , Proteína Quinase Ativada por DNA/genética , Proteínas de Ligação a DNA/genética , Modelos Animais de Doenças , Ilhas Genômicas/genética , Humanos , Subunidade gama Comum de Receptores de Interleucina/genética , Ferro/metabolismo , Lipopolissacarídeos/metabolismo , Proteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos NOD , Camundongos Obesos , Camundongos SCID , Salmonella typhi/crescimento & desenvolvimento , Sideróforos/metabolismo , Células THP-1/microbiologia , Febre Tifoide , Virulência/genética
14.
Arch Microbiol ; 201(10): 1333-1349, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31309236

RESUMO

The present study aims to characterize nodule endophytic bacteria of spontaneous lupine plants regarding their diversity and their plant growth promoting (PGP) traits. The potential of PGPR inoculation was investigated to improve white lupine growth across controlled, semi-natural and field conditions. Lupinus luteus and Lupinus angustifolius nodules were shown inhabited by a large diversity of endophytes. Several endophytes harbor numerous plant growth promotion traits such as phosphates solubilization, siderophores production and 1-aminocyclopropane-1-carboxylate deaminase activity. In vivo analysis confirmed the plant growth promotion ability of two strains (Paenibacillus glycanilyticus LJ121 and Pseudomonas brenneri LJ215) in both sterilized and semi-natural conditions. Under field conditions, the co-inoculation of lupine by these strains increased shoot N content and grain yield by 25% and 36%, respectively. These two strains Paenibacillus glycanilyticus LJ121 and Pseudomonas brenneri LJ215 are effective plant growth-promoting bacteria and they may be used to develop an eco-friendly biofertilizer to boost white lupine productivity.


Assuntos
Endófitos/fisiologia , Lupinus/microbiologia , Paenibacillus/fisiologia , Raízes de Plantas/microbiologia , Pseudomonas/fisiologia , Microbiologia do Solo , Endófitos/genética , Endófitos/isolamento & purificação , Lupinus/crescimento & desenvolvimento , Desenvolvimento Vegetal , Caules de Planta/química , Caules de Planta/microbiologia , Sideróforos/metabolismo , Tunísia
15.
Planta ; 250(4): 1339-1354, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31278466

RESUMO

MAIN CONCLUSION: The ratio of nicotianamine to deoxymugenic acid controls tissue-specific metal homeostasis in rice and regulates metal delivery to the endosperm. The metal-chelating phytosiderophores nicotianamine (NA) and 2'deoxymugenic acid (DMA) are significant factors for the control of metal homeostasis in graminaceous plants. These compounds are thought to influence metal homeostasis, but their individual roles and the effect of altering the NA:DMA ratio are unknown. We purposely generated rice lines with high and low NA:DMA ratios (HND and LND lines, respectively). The HND lines accumulated more iron (Fe), zinc (Zn), manganese (Mn) and copper (Cu) in the endosperm through the mobilization of Fe, Zn and Mn from the seed husk to the endosperm. In contrast, Fe, Zn and Mn were mobilized to the husk in the LND lines, whereas Cu accumulated in the endosperm. Different groups of metals are, therefore, taken up, transported and sequestered in vegetative tissues in the HND and LND lines to achieve this metal distribution pattern in the seeds. We found that different sets of endogenous metal homeostasis genes were modulated in the HND and LND lines to achieve differences in metal homeostasis. Our findings demonstrate that the NA:DMA ratio is a key factor regulating metal homeostasis in graminaceous plants. These findings can help formulate refined strategies to improve nutrient composition and nutrient use efficiency in crop plants.


Assuntos
Ácido Azetidinocarboxílico/análogos & derivados , Metais/metabolismo , Oryza/fisiologia , Sideróforos/metabolismo , Ácido Azetidinocarboxílico/metabolismo , Transporte Biológico , Endosperma/genética , Endosperma/fisiologia , Homeostase , Ferro/metabolismo , Manganês/metabolismo , Oryza/genética , Transcriptoma , Zinco/metabolismo
16.
Chemosphere ; 236: 124347, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31310975

RESUMO

Pyoverdine (Pvd) is a bacterial siderophore produced by some Pseudomonads species that can bind copper in addition to iron in soil. Pvd is expected to alter the dynamics and the ecotoxicity of Cu in vineyard soils. This study investigated the extent to which the mobility and the phytoavailability of Cu varied among vineyard soils with different pH and how they were affected by a supply of Pvd. Pvd was supplied (or not) to ten vineyard topsoils with pH ranging from 5.9 to 8.6 before metal was extracted with 0.005 M CaCl2. Cu mobility was assessed through its total concentration and Cu phytoavailability through its free ionic concentration measured in the CaCl2 extract. Cu mobility varied by a factor of six and Cu phytoavailability by a factor of 5000 among the soil samples. In the CaCl2 extract, the concentration of Cu2+ was not correlated with the concentration of total Cu but was correlated with pH. This revealed that Cu phytoavailability depends to a great extent on Cu complexation in soil pore water, the latter being highly sensitive to pH. Adding Pvd enhanced the mobility of Cu in the soils including in carbonate soils. The Pvd-mobilization factor for Cu varied from 1.4 to 8 among soils, linked to the availability of Fe and Al in the solid phase and to Pvd partitioning between the solid and the liquid phase. Adding Pvd reduced the concentration of Cu2+ in CaCl2 extract, which challenges the idea of using Pvd-producing bacteria to promote Cu phytoextraction.


Assuntos
Biodegradação Ambiental , Cobre/análise , Oligopeptídeos/metabolismo , Sideróforos/metabolismo , Poluentes do Solo/análise , Fazendas , Ferro/análise , Solo/química
17.
Plant Physiol Biochem ; 142: 15-21, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31252370

RESUMO

Drought represents a major constraint for agricultural productivity and food security worldwide. Plant growth promoting actinobacteria have attracted the attention as a promising approach to enhance plant growth and yield under stressful conditions. In this regard, bioprospecting in arid and semi-arid environments could reveal uncommon bacteria with improved biological activities. In the present study, the ability of actinobacteria isolated from a semi-arid environment (Saudi Arabia) to mitigate the negative impact of drought on growth and physiology of maize, a drought-sensitive crop, has been investigated. Among the different actinobacterial isolates screened for secondary metabolites production and biological activities, isolate Ac5 showed high ability of flavonoid, phytohormones and siderophores production. Moreover, Ac5 improved the growth and photosynthesis and induced a global metabolic change in the bacterized plants under water-deficit conditions. Interestingly, Ac5 treatment significantly mitigated the detrimental effects of drought stress on maize. Reduced H2O2 accumulation and lipid peroxidation accompanied with higher levels of molecular antioxidants (total ascorbate, glutathione, tocopherols, phenolic acids and flavonoids) were observed in the bacterized plants. From the osmoregulation point of view, drought-stressed bacterized maize accumulated higher levels of compatible solutes, such as sucrose, total soluble sugars, proline, arginine and glycine betaine, as compared with the non-bacterized plants. Therefore, this study highlights the comprehensive impact of actinobacteria on the global plant metabolism and suggests the potential utilization of actinobacteria isolated from semi-arid environments to mitigate the negative impact of drought on crop plants.


Assuntos
Streptomyces/química , Streptomyces/fisiologia , Zea mays/fisiologia , Antioxidantes/metabolismo , Clima Desértico , Secas , Flavonoides/análise , Peróxido de Hidrogênio/metabolismo , Malondialdeído/metabolismo , Metaboloma , Osmorregulação , Oxirredução , Fenóis/análise , Fotossíntese , Rizosfera , Metabolismo Secundário , Sideróforos/metabolismo , Microbiologia do Solo , Streptomyces/isolamento & purificação , Zea mays/microbiologia
18.
World J Microbiol Biotechnol ; 35(6): 93, 2019 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-31187335

RESUMO

Siderophores are extra-cellular inducible compounds produced by aerobic microorganisms and plants to overcome iron insolubility via its chelation and then uptake inside the cell. This work aims to study the characteristics of siderophore that is produced by a rhizosphere-inhabiting fungus. This fungus has been morphologically and molecularly identified as Aspergillus niger with the ability to produce 87% siderophore units. The obtained siderophore in PDB medium gave a positive result with tetrazolium test and a characteristic spectrum with a maximum absorbance at 450 nm in FeCl3 test that did not shift in response to different pH degrees (5-9). This indicates that the obtained siderophore is a trihydroxymate in nature. After purification, the FTIR and NMR analyses showed that the obtained siderophore is considered to be ferrichrome. The purified siderophore has been further evaluated as a tool to extract uranium, thorium and rare earth elements (REEs) from Egyptian phosphorites obtained from Abu Tartur Mine area. The inductively coupled plasma atomic emission spectroscopy analysis showed that the highest removal efficiency percentage was for uranium (69.5%), followed by samarium (66.7%), thorium (55%), lanthanum (51%), and cerium (50.1%). This result confirmed the ability of hydroxymate siderophores to chelate the aforementioned precious elements, a result that paves the way for bioleaching to replace abiotic techniques in order to save the cost of such elements in an environmentally friendly way.


Assuntos
Aspergillus niger/isolamento & purificação , Aspergillus niger/metabolismo , Sideróforos/isolamento & purificação , Sideróforos/metabolismo , Microbiologia do Solo , Aspergillus niger/classificação , Aspergillus niger/genética , Egito , Ácidos Graxos/análise , Ferricromo , Concentração de Íons de Hidrogênio , Ferro , Minerais , Fosfatos , Rizosfera
19.
Ecotoxicol Environ Saf ; 181: 265-273, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31201958

RESUMO

The application of palygorskite (PAL) for potentially toxic trace elements (Cd2+, Ni2+, etc.) remediation in polluted soil can substantially reduce the bioavailability and toxicity of these hazard materials. However, the secretion of organic acids and siderophores by microorganisms might result in the re-mobilization of cadmium (Cd) in PAL-bound forms (PAL-Cd). In this study, the interactive effects between Cd stabilized by PAL and mobilized by siderophores from Pseudomonas fluorescens were performed with four flask-shaking experimental treatments, namely, strain with or without an ability of siderophores production respectively associated with or without PAL-Cd. The GC-MS and UHPLC-MS test methods were used to analyze the concentrations of metabolites. Results showed that the Cd mobilized by strain with siderophores production was 22.1% higher than that of strain without the ability of siderophores production (p < 0.05). The mobilization of Cd in PAL in turn significantly reduced the siderophores production of Pseudomonas fluorescens by 25.1% (p < 0.05). The numbers of metabolites significantly up-regulated and down-regulated were 9 and 22 in strain groups with PAL-Cd addition compared with the groups without PAL-Cd, respectively. Metabolomics analysis revealed that the mobilized Cd affects the signal transduction pathway and primary metabolic processes, reduces the metabolic capacity of pentose phosphate pathway, glycolysis and tricarboxylic acid cycle pathway. These changes inhibit the ability of strain to biosynthesize amino acids during the mobilization processes, further reducing the capacity of Pseudomonas fluorescens to produce siderophores. This study provides a useful information on how to select soil Cd-stabilizing materials in a targeted manner and how to avoid Cd re-mobilization by siderophores.


Assuntos
Cádmio/análise , Compostos de Magnésio , Pseudomonas fluorescens/metabolismo , Sideróforos/metabolismo , Compostos de Silício , Poluentes do Solo/análise
20.
J Appl Microbiol ; 127(3): 825-844, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31216598

RESUMO

AIM: Tea (Camellia sinensis (L.) O. Kuntze) is an economically important caffeine-containing beverage crop with massive plantation in the Northeast corner of the agroclimatic belt of India. The main aim of the work was to isolate, identify and characterize the native plant growth promoting endophytes associated with tea for future microbe based bioformulation. METHODS AND RESULTS: A total of 129 endophytic bacteria were isolated and characterized for plant growth promoting traits such as indole-3-acetic acid (IAA), phosphate solubilization, ammonia production, biocontrol traits like siderophore and extracellular enzyme production. BOX-PCR fingerprinting was used to differentiate the various bacterial isolates obtained from six different tea species. 16S rRNA sequencing and blast analysis showed that these isolates belonged to different genera, that is, Bacillus, Brevibacterium, Paenibacillus and Lysinibacillus. Lysinibacillus sp. S24 showed the highest phosphate solubilization and IAA acid production efficiency of 268·4 ± 14·3 and 13·5 ± 0·5 µg ml-1 , respectively. Brevibacterium sp. S91 showed the highest ammonia production of 6·2 ± 0·5 µmol ml-1 . Chitinase, cellulase, protease and pectinase activities were shown by 4·6, 34·1, 27·13 and 13·14% of the total isolates, respectively. Similarly, 41% of the total isolates were positive for 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity. Further, the potent PGP isolates, S24 and S91 were able to enhance the vegetative parameters such as dry/fresh weight of root and shoot of tea plants in nursery conditions. CONCLUSION: Our findings corroborate that tea endophytic bacteria possess the potential to demonstrate multiple PGP traits both, in vivo and in vitro and have the potential for further large-scale trials. SIGNIFICANCE AND IMPACT OF THE STUDY: The exploration of tea endophytic bacterial community is suitable for the development of bioformulations for an integrated nutrient management and thus sustainable crop production and decreasing the hazardous effects of chemical fertilizers on the environment and human health.


Assuntos
Camellia sinensis/microbiologia , Endófitos/fisiologia , Desenvolvimento Vegetal , Aminoácidos Cíclicos , Bacillus/genética , Bacillus/isolamento & purificação , Bacillus/metabolismo , Brevibacterium/genética , Brevibacterium/isolamento & purificação , Brevibacterium/metabolismo , Camellia sinensis/crescimento & desenvolvimento , Endófitos/isolamento & purificação , Índia , Ácidos Indolacéticos/metabolismo , Paenibacillus/genética , Paenibacillus/isolamento & purificação , Paenibacillus/fisiologia , Filogenia , Raízes de Plantas/microbiologia , RNA Ribossômico 16S/genética , Sideróforos/metabolismo
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