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1.
World J Microbiol Biotechnol ; 36(3): 47, 2020 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-32144505

RESUMO

Beauveria bassiana (Bals.) Vuillemin (B. bassiana) is an entomopathogenic fungus that establishes endophytic symbiosis with plants. In the present study, the effects of B. bassiana strains colonization in growing Zea mays L. (Z. mays), crop production, and drought tolerance were evaluated. Z. mays seeds were inoculated with B. bassiana strains (GHA, PTG4, and PTG6), using 1 × 106 blastospores/mL and methyl cellulose (MC) or cornstarch (CS) as adherents. Colonization was determined by B. bassiana recovery from plant tissues plated on PDA medium. Plant height, fresh and dry weight, and flowering time were analyzed to assess plant performance. Drought tolerance was evaluated by stopping watering for 10 days, watering again, and determining vigor recovery after 24 h. Results showed 100% endophytic roots colonization, regardless of adherent type or strain tested. Colonization was variable in shoots and leaves, but GHA strain achieved the highest inoculation rates, including 88% in stems and 50% in leaves, which did not depend on adherent type used; for PTG4 strain, adherent type had an important effect (MC = 100% stems and leaves; CS = 63% stems and 25% leaves). For PTG6 strain, the best adherent type was CS (71% stems and 75% leaves), whereas MC showed variable inoculation percentage (25% stems and 75% leaves). Interestingly, only MCPTG4 treatment showed consistent positive effects on germination percentage (day 5 = 46 ± 2%; day 14 = 87 ± 7%) compared with controls (CC = 63 ± 4%, CMC = 50 ± 3%, CCS = 47 ± 0%). In addition, the other treatments showed low germination percentages at day 5 (7 ± 7% to 46 ± 2%), which recovered at day 14 (53 ± 0% to 73 ± 8%), except for MCPTG6 treatment with 23 ± 10% germination. About plant performance, not significant effects on plant height and fresh/dry weight in all the treatments were observed. However, B. bassiana-treated plants, using either GHA, PTG4 or PTG6 strains, and MC as adherent, showed tolerance to drought and flowered one to two weeks earlier, providing evidence supporting further applications of these seed treatments in agricultural systems, for abiotic stress sustainable management practices.


Assuntos
Beauveria/fisiologia , Secas , Endófitos/fisiologia , Flores/crescimento & desenvolvimento , Estresse Fisiológico , Zea mays/crescimento & desenvolvimento , Germinação , Desenvolvimento Vegetal , Folhas de Planta/microbiologia , Sementes/crescimento & desenvolvimento , Sementes/microbiologia , Simbiose , Zea mays/microbiologia
2.
J Agric Food Chem ; 68(6): 1634-1644, 2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-31961687

RESUMO

A novel microbial consortium (NZDC-6) was screened and characterized to detoxify the estrogenic mycotoxin zearalenone (ZEA), which commonly contaminates maize and is a major threat to food and health security. We found NZDC-6 to be thermophilic and highly effective, with a 90.3% ZEA degradation ratio at an optimum temperature of 60 °C. NZDC-6 was also effective at degrading the more estrogenic ZEA cognates, α-zearalenol (α-ZAL) and ß-zearalenol (ß-ZAL), with >90% degradation ratios. To evaluate a practical application, ZEA-contaminated corncobs were treated with NZDC-6 via semisolid fermentation. Measurements of physicochemical parameters and 16S microbial diversity and redundancy analysis (RDA) indicated that ZEA removal was most efficient at a low corncob solid content (< 5%), as a high solid content overwhelmed the microbial metabolic load, leading to increased dissolved oxygen and lowered pH. Our results demonstrate that the control of environmental variables is crucial for effective ZEA microbial removal in practical applications.


Assuntos
Bactérias/metabolismo , Consórcios Microbianos , Zea mays/microbiologia , Zearalenona/metabolismo , Bactérias/genética , Bactérias/crescimento & desenvolvimento , Bactérias/isolamento & purificação , Biodegradação Ambiental , Fermentação , Contaminação de Alimentos/análise
3.
Phytopathology ; 110(2): 494-504, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31464158

RESUMO

Cochliobolus heterostrophus is the causal agent of southern corn leaf blight, a destructive disease on maize worldwide. However, how it regulates virulence on maize is still largely unknown. Here, we report that two copper transporter genes, ChCTR1 and ChCTR4, are required for its virulence. chctr1 and chctr4 mutants showed attenuated virulence on maize compared with the wild-type strain TM17 but development phenotypes of those mutants on media with or without infection-related stress agents were the same as the wild-type strain. Moreover, ChCTR1 and ChCTR4 play critical roles in appressorium formation and mutation of ChCTR1 or ChCTR4 suppresses the appressorium formation. Furthermore, copper-chelating agent ammonium tetrathiomolybdate suppressed the appressorium formation and virulence of C. heterostrophus on maize, whereas copper ions enhanced the appressorium formation and virulence on maize. The results indicate that copper ions are required for appressorium formation and virulence of C. heterostrophus on maize and are acquired from the environment by two copper transporters: ChCTR1 and ChCTR4.


Assuntos
Ascomicetos , Virulência , Zea mays , Ascomicetos/patogenicidade , Ascomicetos/fisiologia , Cobre/química , Íons/química , Doenças das Plantas/microbiologia , Zea mays/microbiologia
4.
Int J Food Microbiol ; 313: 108376, 2020 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-31731141

RESUMO

Maize is an important staple crop for the majority of the population in Uganda. However, in tropical and subtropical climates, maize is frequently contaminated with aflatoxins, a group of cancer-causing and immuno-suppressive mycotoxins produced by Aspergillus section Flavi fungi. In Uganda, there is limited knowledge about the causal agents of aflatoxin contamination. The current study determined both the aflatoxin levels in pre-harvest maize across Uganda and the structures of communities of aflatoxin-producing fungi associated with the maize. A total of 256 pre-harvest maize samples were collected from 23 major maize-growing districts in eight agro-ecological zones (AEZ). Maize aflatoxin content ranged from 0 to 3760 ng/g although only around 5% for Ugandan thresholds. For EU it is about 16% of the samples contained aflatoxin concentrations above tolerance thresholds. A total of 3105 Aspergillus section Flavi isolates were recovered and these were dominated by the A. flavus L morphotype (89.4%). Densities of aflatoxin-producing fungi were negatively correlated with elevation. Farming systems and climatic conditions of the AEZ are thought to have influenced communities' structure composition. Fungi from different AEZ varied significantly in aflatoxin-producing abilities and several atoxigenic genotypes were identified. The extremely high aflatoxin concentrations detected in some of the studied regions indicate that management strategies should be urgently designed for use at the pre-harvest stage. Atoxigenic genotypes detected across Uganda could serve as aflatoxin biocontrol agents to reduce crop contamination from fields conditions and throughout the maize value chain.


Assuntos
Aflatoxinas/análise , Aspergillus/metabolismo , Contaminação de Alimentos/análise , Zea mays/microbiologia , Agricultura , Aspergillus/genética , Aspergillus/isolamento & purificação , Ecologia , Uganda , Zea mays/química , Zea mays/crescimento & desenvolvimento
5.
J Dairy Sci ; 103(1): 379-395, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31629529

RESUMO

Dairy farmers are often challenged with the need to feed high-moisture corn (HMC) after less than 30 d of fermentation. The objective this study was to assess the effects of microbial inoculation and particle size on fermentation profile, aerobic stability, and ruminal in situ starch degradation of HMC ensiled for a short period. High-moisture corn was harvested, coarsely ground (3,798 ± 40 µm, on average) or finely ground (984 ± 42 µm, on average), then ensiled in quadruplicate vacuum pouches untreated (CON) or with the following treatments: Lactobacillus plantarum CH6072 at 5 × 104 cfu/g and Enterococcus faecium CH212 at 5 × 104 cfu/g of fresh forage (LPEF); or Lactobacillus buchneri LB1819 at 7.5 × 104 cfu/g and Lactococcus lactis O224 at 7.5 × 104 cfu/g (LBLL). Silos were allowed to ferment for 14 or 28 d. Ruminal in situ starch degradation increased when HMC was finely ground. In addition, in situ starch degradation was greater and aerobic stability increased approximately 5-fold with LBLL compared with CON and LPEF. An interaction between microbial inoculation and storage length occurred for lactic acid. At 14 d, concentrations of lactic acid were greatest in LPEF and lowest in LBLL. Lactic acid concentrations increased from 14 to 28 d with CON and LPEF, but decreased with LBLL. At 28 d, concentrations of lactic acid were lower in LBLL compared with CON and LPEF. An interaction between particle size, microbial inoculation, and storage length occurred for acetic acid and ammonia-N. At 14 and 28 d, acetic acid concentrations were greatest in finely ground LBLL followed by coarsely ground LBLL. Ammonia-N concentrations increased across all treatments from 0 to 28 d. At 14 and 28 d, concentrations of ammonia-N were greatest in finely ground LBLL and lowest in coarsely ground CON and coarsely ground LPEF. Results from this study suggest that L. buchneri LB1819 can produce acetic acid in as little as 14 d, and that by 28 d, it has the potential to improve the aerobic stability of HMC. Additionally, results indicate that L. buchneri LB1819 has the potential to improve ruminal degradation of starch by 28 d of storage. Finally, results confirm enhanced fermentation and improved ruminal starch degradation with finely ground HMC by 28 d of storage.


Assuntos
Enterococcus faecium/fisiologia , Lactobacillus/fisiologia , Silagem/análise , Amido/metabolismo , Zea mays , Ácido Acético/metabolismo , Aerobiose , Inoculantes Agrícolas , Animais , Fermentação , Lactobacillus/classificação , Tamanho da Partícula , Silagem/microbiologia , Amido/química , Zea mays/metabolismo , Zea mays/microbiologia
6.
J Appl Microbiol ; 128(1): 242-254, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31559664

RESUMO

AIMS: To study the antimicrobial agents of the Bacillus velezensis strain HC6 and assess the application potential of B. velezensis HC6 in maize. METHODS AND RESULTS: We applied a dual culture technique to test the antimicrobial activity of B. velezensis HC6 against bacteria and fungi of common contaminated crops. Bacillus velezensis HC6 showed antagonistic action on pathogenic fungi, including Aspergillus and Fusarium, as well as pathogenic bacteria (especially Listeria monocytogenes). When applied in maize, B. velezensis HC6 could also inhibit the growth of multiple pathogenic fungi and reduce their production of aflatoxin and ochratoxin. Three kinds of antimicrobial lipopeptides, including iturin, fengycin and surfactin were identified in B. velezensis HC6 culture supernatant by high-performance liquid chromatography and MALDI-TOF mass spectrometry. Iturin and fengycin showed obvious antimicrobial activity to the tested fungal strains. CONCLUSIONS: Bacillus velezensis HC6 produces three kinds of lipopeptides which showed antimicrobial activity against several common pathogenic fungi and bacteria. Bacillus velezensis HC6 is potential to be biocontrol bacteria in maize. SIGNIFICANCE AND IMPACT OF THE STUDY: Bacillus velezensis HC6 shows obvious antimicrobial activity to important crops pathogenic fungi which usually produce mycotoxins that are harmful to animal and human health. We demonstrate that three different types of lipopeptides produced by B. velezensis contributed to the antimicrobial activity. Bacillus velezensis HC6 has the potential to be effective biocontrol agent in crops.


Assuntos
Anti-Infecciosos , Bacillus/fisiologia , Agentes de Controle Biológico , Lipopeptídeos/metabolismo , Zea mays/microbiologia , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Bacillus/química , Bactérias/efeitos dos fármacos , Fungos/efeitos dos fármacos , Fungos/crescimento & desenvolvimento , Fungos/metabolismo , Lipopeptídeos/química , Lipopeptídeos/farmacologia , Micotoxinas/metabolismo , Doenças das Plantas/microbiologia
7.
Pak J Pharm Sci ; 32(4): 1679-1686, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31608890

RESUMO

Four fungal isolates were identified in this study of which three were Aspergillus species with Aspergillus flavus having the highest frequency followed by A. parasiticus. The result of high frequency of Aspergillus flavus and Aspergillus parasiticus in the Zea mays sample revealed production of aflatoxins. Maize sample in Awka was found to contain aflatoxin B1 (9.60ppb) and B2 (13.3ppb). Inhibition of A. flavus and A. parasiticus with Azadirachta indica and Garcinia kola seed extracts showed that the test plant extracts were effective for reducing mycelial growth on the test organism. Methanolic extract of G. kola showed antifungal inhibitory activity on the test organisms and the highest at 10% concentration. With ethanol extracts of G. kola, the antifungal activity was effective i.e. for inhibition of A. flavus and A. parasiticus, with A. parasiticus having the higher percentage inhibition at 10%. Inhibiting growth of Aspergillus flavus and Aspergillus parasiticus using methanolic and ethanolic extracts of neem seeds was effective in the inhibition of the test organism at 10%. The methanolic and ethanolic extracts of combined Garcinia kola and neem seeds revealed effective inhibition of A. flavus and A. parasiticus with ethanolic extracts of the combined test plants exerting the highest inhibition against A. flavus (80.43±3.62). The extracts from this plant show the ability to suppress growth of toxigenic A. flavus and A. parasiticus. Phytochemical analysis showed that the methanolic and ethanolic extracts of G. kola and neem seeds showed the presence of secondary metabolites and this may be a reason for the inhibitory activity on A. flavus and A. parasiticus. Results from this study will be important in planning a management strategy against aflatoxin-producing fungi and other fungi associated with spoilage of stored food products.


Assuntos
Aflatoxinas/metabolismo , Antifúngicos/farmacologia , Aspergillus/metabolismo , Azadirachta/química , Garcinia kola/química , Zea mays/microbiologia , Aflatoxinas/análise , Antifúngicos/química , Aspergillus/efeitos dos fármacos , Aspergillus/isolamento & purificação , Aspergillus/patogenicidade , Etanol/química , Microbiologia de Alimentos , Armazenamento de Alimentos , Metanol/química , Testes de Sensibilidade Microbiana , Nigéria , Compostos Fitoquímicos/análise , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Sementes/microbiologia
8.
Int J Mol Sci ; 20(20)2019 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-31614702

RESUMO

Bacillus velezensis FZB42 is able to activate induced systemic resistance (ISR) to enhance plant defense response against pathogen infections. Though the roles of microRNAs (miRNAs) in Bacillus-triggered ISR have been reported in Arabidopsis, the maize miRNAs responsible for the Bacillus-activated ISR process have not been discovered. To explore the maize miRNAs involved in ISR, maize miRNAs in response to FZB42 (ISR activating), FZB42△sfp△alss (deficient in triggering ISR), and a control for 12 h were sequenced. A total of 146 known miRNAs belonging to 30 miRNA families and 217 novel miRNAs were identified. Four miRNAs specifically repressed in FZB42-treatment were selected as candidate ISR-associated miRNAs. All of them contained at least one defense response-related cis-element, suggesting their potential roles in activating the ISR process. Interestingly, three of the four candidate ISR-associated miRNAs belong to the conserved miR169 family, which has previously been confirmed to play roles in abiotic stress response. Moreover, 52 mRNAs were predicted as potential targets of these candidate ISR-associated miRNAs through TargetFinder software and degradome sequencing. Gene Ontology (GO) and network analyses of target genes showed that these differentially expressed miRNA might participate in the ISR process by regulating nuclear factor Y transcription factor. This study is helpful in better understanding the regulatory roles of maize miRNAs in the Bacillus-activated ISR process.


Assuntos
Resistência à Doença , MicroRNAs/genética , Zea mays/genética , Bacillus/patogenicidade , MicroRNAs/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Zea mays/imunologia , Zea mays/microbiologia
9.
Nat Genet ; 51(10): 1540-1548, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31570888

RESUMO

Rhizoctonia solani is a widely distributed phytopathogen that causes banded leaf and sheath blight in maize and sheath blight in rice. Here, we identified an F-box protein (ZmFBL41) that confers resistance to banded leaf and sheath blight through a genome-wide association study in maize. Rice overexpressing ZmFBL41 showed elevated susceptibility to R. solani. Two amino acid substitutions in this allele prevent its interaction with ZmCAD, which encodes the final enzyme in the monolignol biosynthetic pathway, resulting in the inhibition of ZmCAD degradation and, consequently, the accumulation of lignin and restriction of lesion expansion. Knocking out the ZmCAD-homologous gene OsCAD8B in rice enhanced susceptibility to R. solani. The results reveal a susceptibility mechanism in which R. solani targets the host proteasome to modify the secondary metabolism of the plant cell wall for its invasion. More importantly, it provides an opportunity to generate R. solani-resistant varieties of different plant species.


Assuntos
Resistência à Doença/imunologia , Variação Genética , Doenças das Plantas/imunologia , Folhas de Planta/imunologia , Proteínas de Plantas/genética , Rhizoctonia/fisiologia , Zea mays/imunologia , Resistência à Doença/genética , Regulação da Expressão Gênica de Plantas , Marcadores Genéticos , Estudo de Associação Genômica Ampla , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Folhas de Planta/genética , Folhas de Planta/microbiologia , Zea mays/genética , Zea mays/microbiologia
10.
Microb Cell Fact ; 18(1): 185, 2019 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-31665025

RESUMO

BACKGROUND: The consequence of simultaneous and sequential inoculation of T. asperellum and B. amyloliquefaciens cultures with respect to growth rate, differential expression of vital genes and metabolites were examined. RESULTS: The competition was observed between T. asperellum and B. amyloliquefaciens under co-cultivation. The proliferation of Trichoderma was reduced in the simultaneous inoculation (TB1) method, possibly due to the fastest growth of Bacillus. Both T. asperellum and B. amyloliquefaciens were proliferated in sequential inoculation method (TB2). The sequential inoculation method (TB2) upregulated the expression of metabolites and vital genes (sporulation, secondary metabolites, mycoparasitism enzymes and antioxidants) in Trichoderma and downregulated in Bacillus and vice versa in co-inoculation method (TB1). The metabolic changes in the co-culture promoted the maize plant growth and defense potential under normal and biotic stress conditions. CONCLUSION: The metabolites produced by the co-culture of T. asperellum and B. amyloliquefaciens improved the maize plant growth and defense potential under normal and biotic stress conditions.


Assuntos
Bacillus amyloliquefaciens , Agentes de Controle Biológico/metabolismo , Trichoderma , Zea mays , Bacillus amyloliquefaciens/genética , Bacillus amyloliquefaciens/crescimento & desenvolvimento , Bacillus amyloliquefaciens/metabolismo , Técnicas de Cocultura/métodos , Fermentação , Regulação da Expressão Gênica , Trichoderma/genética , Trichoderma/crescimento & desenvolvimento , Trichoderma/metabolismo , Zea mays/crescimento & desenvolvimento , Zea mays/microbiologia
11.
Ecotoxicol Environ Saf ; 186: 109744, 2019 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-31627093

RESUMO

Biological strategy of utilization of plants-microbe's interactions to remediate cadmium (Cd) contaminated soils is effective and practical. However, limited evidence at transcriptome level is available about how microbes work with host plants to alleviate Cd stress. In the present study, comparative transcriptomic analysis was performed between maize seedlings inoculated with arbuscular mycorrhizal (AM) fungi and non-AM fungi inoculation under distinct concentrations of CdCl2 (0, 25, and 50 mg per kg soil). Significantly higher levels of Cd were found in root tissues of maize colonized by AM fungi, whereas, Cd content was reduced as much as 50% in leaf tissues when compared to non-AM seedlings, indicating that symbiosis between AM fungi and maize seedlings can significantly block translocation of Cd from roots to leaf tissues. Moreover, a total of 5827 differentially expressed genes (DEG) were determined and approximately 68.54% DEGs were downregulated when roots were exposed to high Cd stress. In contrast, 67.16% (595) DEGs were significantly up-regulated when seedlings were colonized by AM fungi under 0 mg CdCl2. Based on hierarchical clustering analysis, global expression profiles were split into eight distinct clusters. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that hundreds of genes functioning in plant hormone signal transduction, mitogen-activated protein kinase (MAPK) signaling pathway and glutathione metabolism were enriched. Furthermore, MapMan pathway analysis indicated a more comprehensive overview response, including hormone metabolism, especially in JA, glutathione metabolism, transcription factors and secondary metabolites, to Cd stress in mycorrhizal maize seedlings. These results provide an overview, at the transcriptome level, of how inoculation of maize seedlings by AM fungi could facilitate the relief of Cd stress.


Assuntos
Cádmio/efeitos adversos , Glomeromycota/fisiologia , Micorrizas/fisiologia , Poluentes do Solo/efeitos adversos , Simbiose , Transcriptoma , Zea mays/efeitos dos fármacos , Cádmio/metabolismo , Regulação para Baixo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Plântula/metabolismo , Solo/química , Poluentes do Solo/metabolismo , Estresse Fisiológico , Zea mays/genética , Zea mays/metabolismo , Zea mays/microbiologia
12.
Mol Plant Microbe Interact ; 32(12): 1581-1597, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31657672

RESUMO

Vascular wilt bacteria such as Pantoea stewartii, the causal agent of Stewart's bacterial wilt of maize (SW), are destructive pathogens that are difficult to control. These bacteria colonize the xylem, where they form biofilms that block sap flow leading to characteristic wilting symptoms. Heritable forms of SW resistance exist and are used in maize breeding programs but the underlying genes and mechanisms are mostly unknown. Here, we show that seedlings of maize inbred lines with pan1 mutations are highly resistant to SW. However, current evidence suggests that other genes introgressed along with pan1 are responsible for resistance. Genomic analyses of pan1 lines were used to identify candidate resistance genes. In-depth comparison of P. stewartii interaction with susceptible and resistant maize lines revealed an enhanced vascular defense response in pan1 lines characterized by accumulation of electron-dense materials in xylem conduits visible by electron microscopy. We propose that this vascular defense response restricts P. stewartii spread through the vasculature, reducing both systemic bacterial colonization of the xylem network and consequent wilting. Though apparently unrelated to the resistance phenotype of pan1 lines, we also demonstrate that the effector WtsE is essential for P. stewartii xylem dissemination, show evidence for a nutritional immunity response to P. stewartii that alters xylem sap composition, and present the first analysis of maize transcriptional responses to P. stewartii infection.


Assuntos
Resistência à Doença , Pantoea , Zea mays , Resistência à Doença/genética , Genoma de Planta/genética , Pantoea/fisiologia , Plântula/microbiologia , Xilema/microbiologia , Zea mays/genética , Zea mays/microbiologia
13.
PLoS Pathog ; 15(9): e1008035, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31557268

RESUMO

Phytoplasmas are insect-transmitted bacterial pathogens that colonize a wide range of plant species, including vegetable and cereal crops, and herbaceous and woody ornamentals. Phytoplasma-infected plants often show dramatic symptoms, including proliferation of shoots (witch's brooms), changes in leaf shapes and production of green sterile flowers (phyllody). Aster Yellows phytoplasma Witches' Broom (AY-WB) infects dicots and its effector, secreted AYWB protein 11 (SAP11), was shown to be responsible for the induction of shoot proliferation and leaf shape changes of plants. SAP11 acts by destabilizing TEOSINTE BRANCHED 1-CYCLOIDEA-PROLIFERATING CELL FACTOR (TCP) transcription factors, particularly the class II TCPs of the CYCLOIDEA/TEOSINTE BRANCHED 1 (CYC/TB1) and CINCINNATA (CIN)-TCP clades. SAP11 homologs are also present in phytoplasmas that cause economic yield losses in monocot crops, such as maize, wheat and coconut. Here we show that a SAP11 homolog of Maize Bushy Stunt Phytoplasma (MBSP), which has a range primarily restricted to maize, destabilizes specifically TB1/CYC TCPs. SAP11MBSP and SAP11AYWB both induce axillary branching and SAP11AYWB also alters leaf development of Arabidopsis thaliana and maize. However, only in maize, SAP11MBSP prevents female inflorescence development, phenocopying maize tb1 lines, whereas SAP11AYWB prevents male inflorescence development and induces feminization of tassels. SAP11AYWB promotes fecundity of the AY-WB leafhopper vector on A. thaliana and modulates the expression of A. thaliana leaf defence response genes that are induced by this leafhopper, in contrast to SAP11MBSP. Neither of the SAP11 effectors promote fecundity of AY-WB and MBSP leafhopper vectors on maize. These data provide evidence that class II TCPs have overlapping but also distinct roles in regulating development and defence in a dicot and a monocot plant species that is likely to shape SAP11 effector evolution depending on the phytoplasma host range.


Assuntos
Arabidopsis/microbiologia , Proteínas de Bactérias/metabolismo , Phytoplasma/patogenicidade , Zea mays/microbiologia , Sequência de Aminoácidos , Animais , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Interações entre Hospedeiro e Microrganismos/genética , Interações entre Hospedeiro e Microrganismos/fisiologia , Especificidade de Hospedeiro , Insetos Vetores/microbiologia , Phytoplasma/genética , Phytoplasma/fisiologia , Doenças das Plantas/microbiologia , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Domínios e Motivos de Interação entre Proteínas , Estabilidade Proteica , Homologia de Sequência de Aminoácidos , Fatores de Transcrição/química , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Zea mays/crescimento & desenvolvimento , Zea mays/metabolismo
14.
Ecotoxicol Environ Saf ; 185: 109706, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31561073

RESUMO

Chromium (Cr) is becoming a potential pollutant with the passage of time. Higher intake of Cr does not only affect the productivity of crops, but also the quality of food produced in Cr polluted soils. In the past, foliar application of Fe is widely studied regarding their potential to alleviate Cr toxicity. However, limited information is documented regarding the combined use of PGPR and foliar Fe. Therefore, the current study was conducted to screen Cr tolerant PGPR and examine effect of foliar Fe with and without Cr tolerant PGPR under Cr toxicity (50 and 100 mg kg-1) in maize (Zea mays) production. Out of 15, two Cr tolerant PGPR were screened, identified (Agrobacterium fabrum and Leclercia adecarboxylata) and inoculated with 500 µM Fe. Results confirmed that Agrobacterium fabrum + 500 µM Fe performed significantly best in improving dry weight of roots and shoot, plant height, roots and shoot length and plant leaves in maize under Cr toxicity. A significant increase in chlorophyll a (51.5%), b (55.1%) and total (32.5%) validated the effectiveness of A. fabrum + 500 µM Fe to alleviate Cr toxicity. Improvement in intake of N (64.7%), P (70.0 and 183.3%), K (53.8% and 3.40-fold) in leaves and N (25.6 and 122.2%), P (25.6 and 122.2%), K (33.3% and 97.3%) in roots of maize at Cr50 and Cr100 confirmed that combined application of A. fabrum with 500 µM Fe is a more efficacious approach for alleviation of Cr toxicity and fortification of Fe comparative to sole foliar application of 500 µM Fe.


Assuntos
Agrobacterium/enzimologia , Carbono-Carbono Liases/metabolismo , Cromo/toxicidade , Enterobacteriaceae/enzimologia , Ferro/farmacologia , Poluentes do Solo/toxicidade , Zea mays/efeitos dos fármacos , Agrobacterium/efeitos dos fármacos , Clorofila A/metabolismo , Enterobacteriaceae/efeitos dos fármacos , Ferro/metabolismo , Paquistão , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/microbiologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Rizosfera , Zea mays/crescimento & desenvolvimento , Zea mays/microbiologia
15.
Environ Sci Pollut Res Int ; 26(31): 31822-31833, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31487012

RESUMO

Remediation of heavy metal-contaminated soils is essential for safe agricultural or urban land use, and phytoremediation is among the most effective methods. The success of phytoremediation relies on the size of the plant biomass and bioavailability of the metal for plant uptake. This research was carried out to determine the effect of Ethylenediaminetetraacetic acid (EDTA) ligand and Cu-resistant plant growth-promoting rhizobacteria (PGPR) on phytoremediation efficiency of selected plants as well as fractionation and bioavailability of copper (Cu) in a contaminated soil. The test conditions included three plant species (maize: Zea mays L., sunflower: Helianthus annuus L., and pumpkin: Cucurbita pepo L.) and six treatments, comprising two PGPR strains (Pseudomonas cedrina K4 and Stenotrophomonas sp. A22), two PGPR strains with EDTA, EDTA, and control (without PGPR and EDTA). The combination of EDTA and PGPR enhanced the Cu concentration in both shoot and root tissues and increased the plant biomass. The Cu specific uptake was at a maximum level in the shoots of pumpkin plants when treated with the PGPR strain K4 + EDTA (202 µg pot-1), and the minimum amount of Cu was recorded for sunflower with no PGPR or EDTA addition (29.6 µg pot-1). The result of the PGPR-EDTA treatments showed that the combined application of EDTA and PGPR increased the shoot Cu-specific uptake approximately fourfold in pumpkin. Pumpkin with the highest shoot Cu specific uptake and maize with the highest root Cu specific uptake were the most effective plants in phytoextraction and phytostabilization, respectively. The effectiveness of different PGPR-EDTA treatments in increasing Cu specific uptake by crop plants was assessed by measuring the amount of Cu extracted from the rhizosphere soil adhering to the roots of crop species, by the use of the single extractants Diethylenetriamine pentaacetic acid (DTPA), H2O, NH4NO3, and NH4OAc. PGPR-EDTA treatments increased the amount of water-extractable Cu from rhizosphere soils more than ten times that of the control. The combined application of the EDTA and PGPR reduced the carbonated Fe and Mn oxide-bound Cu in the contaminated soil, and increased the soluble and exchangeable concentration of Cu. Pumpkin, with high shoot biomass and the highest shoot Cu specific uptake was found to be the most effective field crop in phytoextraction of Cu from the contaminated soil. The results of this pot study demonstrated that the EDTA+PGPR treatment could play an important role in increasing the Cu bioavailability and specific uptake by plants, and thus increasing the phytoremediation efficiency of plants in Cu-contaminated areas.


Assuntos
Biodegradação Ambiental/efeitos dos fármacos , Cobre/toxicidade , Ácido Edético/farmacologia , Pseudomonas/efeitos dos fármacos , Poluentes do Solo/toxicidade , Inoculantes Agrícolas , Disponibilidade Biológica , Biomassa , Cobre/análise , Cobre/farmacocinética , Cucurbita/efeitos dos fármacos , Cucurbita/microbiologia , Helianthus/efeitos dos fármacos , Helianthus/microbiologia , Brotos de Planta/efeitos dos fármacos , Pseudomonas/fisiologia , Rizosfera , Poluentes do Solo/farmacocinética , Zea mays/efeitos dos fármacos , Zea mays/microbiologia
16.
Int J Food Microbiol ; 310: 108307, 2019 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-31476582

RESUMO

Aspergillus section Flavi is widely known as a potential threat to contaminate agricultural products and food commodities. In this study, a polyphasic approach consisting of micro- and macro-morphological, chemical and molecular features, was applied to survey the Aspergillus section Flavi population in corn collected from Guangxi, China. Based on multigene phylogenies as well as morphological observations, Aspergillus flavus (192/195), A. arachidicola (1/195), A. pseudonomius (1/195) and A. novoparasiticus (1/195) were found to be the predominant section Flavi population. Among them, 31 representative isolates were selected for mycotoxin determination. The results showed that Aspergillus flavus chemotype I was most common, chemotype IV was also detected with low incidence and low CPA amounts, while chemotypes II and III were absent. Other tested species including A. arachidicola, A. pseudonomius, and A. novoparasiticus produced all types of aflatoxins, but none of them produced CPA. The polyphasic approach applied in this study permitted reliable understanding of the prevailing Aspergillus section Flavi population and their mycotoxin profiles. Knowledge of the prevailing section Flavi population will aid in developing a sustainable strategy to mitigate the effects of aflatoxin contamination. This study suggests that CPA contamination of food should be considered while conducting mycotoxigenic surveys of food commodities, and the same should be considered while planning a bio-control strategy to control aflatoxin contamination.


Assuntos
Contaminação de Alimentos/prevenção & controle , Microbiologia de Alimentos , Zea mays/microbiologia , Aflatoxinas/análise , Aspergillus/genética , Aspergillus/isolamento & purificação , Sequência de Bases , China , Micotoxinas/análise , Filogenia
17.
Ecotoxicol Environ Saf ; 184: 109591, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31514081

RESUMO

Restoring polluted sites by petroleum hydrocarbons is a challenge because of their complexity and persistence in the environment. The main objective of the present study was to investigate the performance of plant-actinobacteria system for the remediation of crude petroleum and pure-polycyclic aromatic hydrocarbons (PAHs) contaminated soils. The endophytic strain Streptomyces sp. Hlh1 was tested for its ability to degrade model PAHs (phenanthrene, pyrene and anthracene) in liquid minimal medium. Streptomyces sp. Hlh1 demonstrated the ability to grow on PAHs as sole carbon and energy source, reaching hydrocarbons removal of 63%, 93% and 83% for phenanthrene, pyrene and anthracene, respectively. Maize plant was chosen to study the impact of Streptomyces sp. Hlh1 inoculation on the dissipation of contaminants and plant growth. Thus, maize seedlings grown in soils contaminated with crude petroleum and pure-PAHs were inoculated with Streptomyces sp. Hlh1. Results showed that the endophyte inoculation increased contaminants removal. Maximum hydrocarbons removal (70%) was achieved in inoculated and planted soil contaminated with crude oil, while 61%, 59%, and 46% of hydrocarbons dissipation were registered for phenanthrene, pyrene and anthracene, respectively. These degradations rates were significantly higher compared to non-inoculated systems in all the treatments evaluated. Further, it was revealed that hydrocarbons (C8-C30) were efficiently degraded in plant-Streptomyces Hlh1 system. Moreover, the inoculation with the actinobacteria resulted significant plant development and enhanced photosynthetic pigments compared to plants grown in the other experimental conditions. The present study provide evidence that the inoculation of maize plants with Streptomyces sp. Hlh1 play a remarkable role in the removal of petroleum hydrocarbons, enhancing plant development in contaminated soils.


Assuntos
Biodegradação Ambiental , Poluição por Petróleo , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Poluentes do Solo/metabolismo , Streptomyces/metabolismo , Zea mays/microbiologia , Endófitos/metabolismo , Desenvolvimento Vegetal , Hidrocarbonetos Policíclicos Aromáticos/análise , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Plântula/microbiologia , Solo/química , Poluentes do Solo/análise , Zea mays/crescimento & desenvolvimento , Zea mays/metabolismo
18.
Int J Mol Sci ; 20(18)2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31514333

RESUMO

Recently, long noncoding RNAs (lncRNAs) have emerged as vital regulators of many biological processes in animals and plants. However, to our knowledge no investigations on plant lncRNAs which respond to arbuscular mycorrhizal (AM) fungi have been reported thus far. In this study, maize roots colonized with AM fungus were analyzed by strand-specific RNA-Seq to identify AM fungi-responsive lncRNAs and construct an associated regulatory network. A total of 1837 differentially expressed protein coding genes (DEGs) were identified from maize roots with Rhizophagus irregularis inoculation. Many AM fungi-responsive genes were homologs to MtPt4, STR, STR2, MtFatM, and enriched pathways such as fatty acid biosynthesis, response to phosphate starvation, and nitrogen metabolism are consistent with previous studies. In total, 5941 lncRNAs were identified, of which more than 3000 were new. Of those, 63 lncRNAs were differentially expressed. The putative target genes of differentially expressed lncRNAs (DELs) were mainly related to phosphate ion transmembrane transport, cellular response to potassium ion starvation, and lipid catabolic processes. Regulatory network analysis showed that DELs might be involved in the regulation of bidirectional nutrient exchange between plant and AM fungi as mimicry of microRNA targets. The results of this study can broaden our knowledge on the interaction between plant and AM fungi.


Assuntos
Redes Reguladoras de Genes , Micorrizas/crescimento & desenvolvimento , Micorrizas/genética , RNA Longo não Codificante/genética , Zea mays/microbiologia , Regulação para Baixo/genética , Regulação Fúngica da Expressão Gênica , Ontologia Genética , Genoma Fúngico , Fenótipo , RNA Longo não Codificante/metabolismo , Plântula/microbiologia , Regulação para Cima/genética
19.
J Appl Microbiol ; 127(6): 1814-1823, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31517423

RESUMO

AIM: The aims of this study were to identify races and mating types of Setosphaeria turcica causing northern corn leaf blight in Heilongjiang province of China and analyse the genetic diversity of S. turcica isolates using SSR markers. METHODS AND RESULTS: Based on gene-for-gene interactions, 13 races of S. turcica (races 0, 1, 2, 3, 12, 13, 23, 123, N, 1N, 12N, 3N and 23N) were isolated from infected corn plants in Heilongjiang province. Races 0 and 1 were the predominant races, and race 23N was identified for the first time in the region. Using two pairs of specific primers, three mating types, 'a', 'Aa' and 'A', were identified, with 'a' being the predominant mating type. SSR markers were used to analyse genetic diversity of 60 S. turcica isolates. Five SSR primers were polymorphic, which resulted in 45 reproducible bands with 2-15 bands for each primer. Cluster analysis separated the isolates into five groups at a similarity coefficient of 0·84. Analysis of molecular variance showed that there was significant correlation between SSR groups and mating type of the isolates. No significant correlation was found between SSR groups and physiological races or geographical location of the isolates. CONCLUSIONS: The work reported that races 0 and 1 were the predominant races, and race 23N was identified for the first time in Heilongjiang province with 'a' being the predominant mating type. There was significant correlation between SSR groups and mating type of S. turcica isolates. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results provide information on population structure and genetic diversity of S. turcica causing Northern corn leaf blight, which will facilitate the development of effective disease management programs.


Assuntos
Ascomicetos/genética , Variação Genética , Doenças das Plantas/microbiologia , Zea mays/microbiologia , Ascomicetos/classificação , China , Análise por Conglomerados , Genes Fúngicos/genética , Genes Fúngicos Tipo Acasalamento/genética , Repetições de Microssatélites/genética
20.
Microbiology ; 165(10): 1075-1085, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31390325

RESUMO

Fusarium verticillioides is one of the key fungal pathogens responsible for maize stalk rot. While stalk rot pathogens are prevalent worldwide, our understanding of the stalk rot virulence mechanism in pathogenic fungi is still very limited. We previously identified the F. verticillioides FvSYN1 gene, which was demonstrated to play an important role in maize stalk rot virulence. FvSyn1 belongs to a family of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins that play critical roles in a variety of developmental processes. In this study, we further characterized the cellular features of the FvSyn1 protein, namely how different motifs contribute to development and virulence in F. verticillioides by generating motif-specific deletion mutants. Microscopic observation showed that the ∆Fvsyn1 mutant exhibits rough and hyper-branched hyphae when compared to the wild-type progenitor. Moreover, the ∆Fvsyn1 mutant was sensitive to cell wall stress agents, resulting in vegetative growth reduction. We showed that the FvSyn1::GFP protein is associated with the endomembrane, but this did not clarify why the deletion of FvSyn1 led to stress sensitivity and aberrant hyphal development. Characterization of the FvSyn1 domains indicated that both the syntaxin N-terminus (SynN) domain and the SNARE C-terminus domain play distinct roles in fungal development, but also function collectively in the context of virulence. We also determined that two domains in FvSyn1 are not required for fumonisin production. Interestingly, these two domains were involved in carbon nutrient utilization, including pectin, starch and sorbitol. This study further characterized the role of FvSyn1 domains in hyphal growth, cell wall stress response and virulence in F. verticillioides.


Assuntos
Proteínas Fúngicas/química , Fusarium/crescimento & desenvolvimento , Fusarium/patogenicidade , Proteínas SNARE/química , Carbono/metabolismo , Parede Celular/fisiologia , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Fusarium/genética , Fusarium/metabolismo , Hifas/crescimento & desenvolvimento , Doenças das Plantas/microbiologia , Domínios Proteicos , Proteínas SNARE/genética , Proteínas SNARE/metabolismo , Deleção de Sequência , Esporos Fúngicos/crescimento & desenvolvimento , Estresse Fisiológico , Virulência , Zea mays/microbiologia
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