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1.
BMC Plant Biol ; 21(1): 498, 2021 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-34715790

RESUMO

BACKGROUND: Effects on maize were assessed of dual inoculation with arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) isolated from other plant species. METHODS: Suspensions of DSE isolated from Stipa krylovii were prepared at different densities (2, 4, and 8 × 105 CFU mL- 1) and inoculated separately (AMF or DSE) or together (AMF + DSE), to explore their effects on maize growth. RESULTS: Inoculation with AMF or medium and high densities of DSE and combined inoculation (AMF + DSE) increased plant above-ground growth and altered root morphology. Differences in plant growth were attributable to differences in DSE density, with negative DSE inoculation responsiveness at low density. AMF promoted plant above-ground growth more than DSE and the high density of DSE promoted root development more than AMF. Combined inoculation might lead to synergistic growth effects on maize at low density of DSE and competitive effects at medium and high DSE densities. CONCLUSIONS: AMF and DSE co-colonized maize roots and they had positive effects on the host plants depending on DSE density. These findings indicate the optimum maize growth-promoting combination of AMF and DSE density and provide a foundation for further exploration of potentially synergistic mechanisms between AMF and DSE in physiological and ecological effects on host plants.


Assuntos
Endófitos/crescimento & desenvolvimento , Micorrizas/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Simbiose/fisiologia , Zea mays/crescimento & desenvolvimento , Zea mays/microbiologia , Produtos Agrícolas/crescimento & desenvolvimento , Produtos Agrícolas/microbiologia
2.
Plant Sci ; 312: 111036, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34620440

RESUMO

Like in mammals, the plant immune system has evolved to perceive damage. Damaged-associated molecular patterns (DAMPs) are endogenous signals generated in wounded or infected tissue after pathogen or insect attack. Although extracellular DNA (eDNA) is a DAMP signal that induces immune responses, plant responses after eDNA perception remain largely unknown. Here, we report that signaling defenses but not direct defense responses are induced after eDNA applications enhancing broad-range plant protection. A screening of defense signaling and hormone biosynthesis marker genes revealed that OXI1, CML37 and MPK3 are relevant eDNA-Induced Resistance markers (eDNA-IR). Additionally, we observed that eDNA from several Arabidopsis ecotypes and other phylogenetically distant plants such as citrus, bean and, more surprisingly, a monocotyledonous plant such as maize upregulates eDNA-IR marker genes. Using 3,3'-Diaminobenzidine (DAB) and aniline blue staining methods, we observed that H2O2 but not callose was strongly accumulated following self-eDNA treatments. Finally, eDNA resulted in effective induced resistance in Arabidopsis against the pathogens Hyaloperonospora arabidopsidis, Pseudomonas syringae, and Botrytis cinerea and against aphid infestation, reducing the number of nymphs and moving forms. Hence, the unspecificity of DNA origin and the wide range of insects to which eDNA can protect opens many questions about the mechanisms behind eDNA-IR.


Assuntos
Arabidopsis/genética , DNA/farmacologia , Resistência à Doença/genética , Resistência à Doença/imunologia , Imunidade Vegetal/genética , Transdução de Sinais/genética , Zea mays/genética , Arabidopsis/imunologia , Arabidopsis/microbiologia , Brassica/genética , Brassica/imunologia , Brassica/microbiologia , Citrus/genética , Citrus/imunologia , Citrus/microbiologia , Produtos Agrícolas/genética , Produtos Agrícolas/imunologia , Produtos Agrícolas/microbiologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética , Genótipo , Phaseolus/genética , Phaseolus/imunologia , Phaseolus/microbiologia , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Solanum/genética , Solanum/imunologia , Solanum/microbiologia , Spinacia oleracea/genética , Spinacia oleracea/imunologia , Spinacia oleracea/microbiologia , Zea mays/imunologia , Zea mays/microbiologia
3.
Int J Mol Sci ; 22(17)2021 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-34502209

RESUMO

The contamination of maize by Fusarium species able to produce mycotoxins raises great concern worldwide since they can accumulate these toxic metabolites in field crop products. Furthermore, little information exists today on the ability of Fusarium proliferatum and Fusarium graminearum, two well know mycotoxigenic species, to translocate from the seeds to the plants up to the kernels. Marketing seeds coated with fungicide molecules is a common practice; however, since there is a growing need for reducing chemicals in agriculture, new eco-friendly strategies are increasingly tested. Technologies based on ionized gases, known as plasmas, have been used for decades, with newer material surfaces, products, and approaches developed continuously. In this research, we tested a plasma-generated bilayer coating for encapsulating prothioconazole at the surface of maize seeds, to protect them from F. graminearum and F. proliferatum infection. A minimum amount of chemical was used, in direct contact with the seeds, with no dispersion in the soil. The ability of F. graminearum and F. proliferatum species to translocate from seeds to seedlings of maize has been clearly proven in our in vitro experiments. As for the use of plasma technology, the combined use of the plasma-generated coating with embedded prothioconazole was the most efficient approach, with a higher reduction of the infection of the maize seminal root system and stems. The debated capability of the two Fusarium species to translocate from seeds to seedlings has been demonstrated. The plasma-generated coating with embedded prothioconazole resulted in a promising sustainable approach for the protection of maize seedlings.


Assuntos
Contaminação de Alimentos/análise , Fungicidas Industriais/farmacologia , Fusarium/crescimento & desenvolvimento , Gases em Plasma/farmacologia , Plântula/crescimento & desenvolvimento , Triazóis/farmacologia , Zea mays/crescimento & desenvolvimento , Contaminação de Alimentos/prevenção & controle , Fusarium/efeitos dos fármacos , Plântula/efeitos dos fármacos , Plântula/microbiologia , Zea mays/efeitos dos fármacos , Zea mays/microbiologia
4.
Arch Virol ; 166(11): 3229-3232, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34524536

RESUMO

The complete genome sequence of a double-stranded RNA (dsRNA) virus, Rhizoctonia solani dsRNA virus 11 (RsRV11), isolated from Rhizoctonia solani AG-1 IA strain 9-11 was determined. The RsRV11 genome is 9,555 bp in length and contains three conserved domains: structural maintenance of chromosomes (SMC) superfamily, phosphoribulokinase (PRK), and RNA-dependent RNA polymerase (RdRp). The RsRV11 genome has two non-overlapping open reading frames (ORFs). ORF1 is predicted to encode a 204.12-kDa protein that shares low but significant amino acid sequence similarity with a putative protein encoded by Rhizoctonia solani RNA virus HN008 (RsRV-HN008). ORF2 potentially encodes a 132.41-kDa protein that contains the conserved domain of the RdRp. Phylogenetic analysis indicated that RsRV11 clustered with RsRV-HN008 in a separate clade from other virus families. This implies that RsRV11 and RsRV-HN008 should be included in a new mycovirus taxon close to the family Megabirnaviridae and that RsRV11 is a new mycovirus.


Assuntos
Micovírus/genética , Genoma Viral , Filogenia , Rhizoctonia/virologia , China , Micovírus/isolamento & purificação , Fases de Leitura Aberta , RNA de Cadeia Dupla , Rhizoctonia/isolamento & purificação , Proteínas Virais/genética , Zea mays/microbiologia
5.
Food Microbiol ; 100: 103865, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34416965

RESUMO

The purpose of this study was to evaluate the inhibitory effect of allyl-isothiocyanate (AITC) and benzyl-isothiocyanate (BITC) on fungal growth and Ochratoxin A (OTA) production by Aspergillus ochraceus, A. carbonarius and A. niger. Here, we found that spore germination and fungal growth of the three fungi were significantly inhibited when the concentration of AITC and BITC was higher than 1.25 µg/mL. The inhibitory effect of AITC or BITC on A. carbonaceus and A. ochraceus was significantly stronger than that of A. niger. Scanning electron microscopy showed that the mycelia of all three fungi were changed by AITC and BITC. Compared with A. ochraceus and A. carbonarius, the damage to A. niger was lower. For OTA production, AITC and BITC could significantly down-regulated the expression of all five OTA biosynthesis genes in A. niger and A. carbonarius. In A. ochraceus, although several OTA biosynthesis genes were up-regulated, the key PKS gene was down-regulated by AITC and BITC. Twenty-five µg/mL of AITC or BITC could reduce the infection of the three fungi on grapes with inhibition rates of 28%-36% during 14 days and prolong the shelf life of grapes. In maize, the OTA production of the three fungi was significantly reduced by 25 µg/mL of AITC and BITC with the inhibition rates 68.04%-93.49% and 65.87%-75.45%, respectively. These results suggest that AITC and BITC can be used as natural fungicides to prevent A. niger, A. carbonarius and A. ochraceus from infecting grapes and maize and control OTA contamination.


Assuntos
Fungos/efeitos dos fármacos , Fungicidas Industriais/farmacologia , Isotiocianatos/farmacologia , Ocratoxinas/biossíntese , Vitis/microbiologia , Zea mays/microbiologia , Contaminação de Alimentos/análise , Fungos/crescimento & desenvolvimento , Fungos/metabolismo
6.
Sci Rep ; 11(1): 17196, 2021 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-34433897

RESUMO

Heavy metals contaminate the soil that alters the properties of soil and negatively affect plants growth. Using microorganism and plant can remove these pollutants from soil. The present investigation was designed to evaluate the induced effect of Bacillus pumilus on maize plant in Cadmium (Cd) contaminated soil. Three different concentrations of Cd (i.e. 0.25, 0.50 and 0.75 mg kg-1) were applied in soil under which maize plants were grown. The germination percentage, shoot length, leaf length, number of leaves, root length, fresh weight and nutrient uptake by maize plant were determined. The experiment was conducted by using complete randomized design (CRD) with three replicates. The result indicated that germination percentage, Shoot length, leaf length, root length, number of leaves, and plant fresh weight were reduced by 37, 39, 39, 32 and 59% respectively at 0.75 mg kg-1 of CdSO4 concentration but when maize seeds inoculated with Bacillus pumilus significantly increased the germination percentage, shoot length, leaf length, number of leaves, plant fresh weight at different concentrations of CdSO4. Moreover, the plant protein were significantly increased by 60% in T6 (0.25 mg kg-1 of CdSO4 + inoculated seed) and Peroxidase dismutase (POD) was also significantly higher by 346% in T6 (0.25 mg kg-1 of CdSO4 + inoculated seed), however, the Superoxide dismutase (SOD) was significantly higher in T5 (0.75 mg kg-1 of CdSO4 + uninoculated seed) and was 769% higher as compared to control. The Cd contents in Bacillus pumilus inoculated maize roots and shoots were decreased. The present investigations indicated that the inoculation of maize plant with Bacillus pumilus can help maize plants to withstand Cd stress but higher concentration of Cd can harm the plant. The Bacillus pumilus has good potential to remediate Cd from soil, and also have potential to reduce the phyto availability and toxicity of Cd.


Assuntos
Bacillus pumilus/metabolismo , Cádmio/toxicidade , Poluentes do Solo/toxicidade , Zea mays/efeitos dos fármacos , Bacillus pumilus/patogenicidade , Biodegradação Ambiental , Cádmio/metabolismo , Sementes/efeitos dos fármacos , Sementes/metabolismo , Sementes/microbiologia , Poluentes do Solo/metabolismo , Estresse Fisiológico , Zea mays/metabolismo , Zea mays/microbiologia
7.
Biosensors (Basel) ; 11(6)2021 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-34202953

RESUMO

Aflatoxin B1 (AFB1), a mycotoxin, is hepatotoxic, carcinogenic, and nephrotoxic in humans and animals, and contaminate a wide range of maize. In this study, an immunochromatographic assay (ICA) based on polystyrene microspheres (PMs) was developed for sensitive and quantitative detection of AFB1 in maize. The amounts of PMs, the condition for activating carboxyl groups of PMs, the amount of monoclonal antibody (mAb), and the volume of the immune probe were optimized to enhance the performance PMs-ICA for point-of-care testing of AFB1 in maize. The PMs-ICA showed the cut-off value of 1 ng/mL in phosphate buffer (PB) and 6 µg/kg in maize samples, respectively. The quantitative limit of detection (qLOD) was 0.27 and 1.43 µg/kg in PB and maize samples, respectively. The accuracy and precision of the PMs-ICA were evaluated by analysis of spiked maize samples with recoveries of 96.0% to 107.6% with coefficients of variation below 10%. In addition, the reliability of PMs-ICA was confirmed by the liquid chromatography-tandem mass spectrometry method. The results indicated that the PMs-ICA could be used as a sensitive, simple, rapid point-of-care testing of AFB1 in maize.


Assuntos
Aflatoxina B1/análise , Zea mays/microbiologia , Animais , Anticorpos Monoclonais , Cromatografia de Afinidade , Humanos , Imunoensaio , Limite de Detecção , Microesferas , Micotoxinas , Poliestirenos/química , Reprodutibilidade dos Testes
8.
Elife ; 102021 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-34292157

RESUMO

The ratio of microbial population size relative to the amount of host tissue, or 'microbial load', is a fundamental metric of colonization and infection, but it cannot be directly deduced from microbial amplicon data such as 16S rRNA gene counts. Because existing methods to determine load, such as serial dilution plating, quantitative PCR, and whole metagenome sequencing add substantial cost and/or experimental burden, they are only rarely paired with amplicon sequencing. We introduce host-associated microbe PCR (hamPCR), a robust strategy to both quantify microbial load and describe interkingdom microbial community composition in a single amplicon library. We demonstrate its accuracy across multiple study systems, including nematodes and major crops, and further present a cost-saving technique to reduce host overrepresentation in the library prior to sequencing. Because hamPCR provides an accessible experimental solution to the well-known limitations and statistical challenges of compositional data, it has far-reaching potential in culture-independent microbiology.


Assuntos
Microbiota/genética , Reação em Cadeia da Polimerase/métodos , Arabidopsis/microbiologia , Bactérias/classificação , Bactérias/genética , Biblioteca Gênica , Interações entre Hospedeiro e Microrganismos/genética , Humanos , Oomicetos , RNA Ribossômico 16S/genética , Zea mays/microbiologia
9.
Sci Rep ; 11(1): 12017, 2021 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-34103568

RESUMO

Clavibacter is an agriculturally important bacterial genus comprising nine host-specific species/subspecies including C. nebraskensis (Cn), which causes Goss's wilt and blight of maize. A robust, simple, and field-deployable method is required to specifically detect Cn in infected plants and distinguish it from other Clavibacter species for quarantine purposes and timely disease management. A multiplex Recombinase Polymerase Amplification (RPA) coupled with a Lateral Flow Device (LFD) was developed for sensitive and rapid detection of Clavibacter and Cn directly from infected host. Unique and conserved genomic regions, the ABC transporter ATP-binding protein CDS/ABC-transporter permease and the MFS transporter gene, were used to design primers/probes for specific detection of genus Clavibacter and Cn, respectively. The assay was evaluated using 52 strains, representing all nine species/subspecies of Clavibacter, other closely related bacterial species, and naturally- and artificially-infected plant samples; no false positives or negatives were detected. The RPA reactions were also incubated in a closed hand at body temperature; results were again specific. The assay does not require DNA isolation and can be directly performed using host sap. The detection limit of 10 pg (~ 3000 copies) and 100 fg (~ 30 copies) was determined for Clavibacter- and Cn-specific primers/probes, respectively. The detection limit for Cn-specific primer/probe set was decreased to 1 pg (~ 300 copies) when 1 µL of host sap was added into the RPA reaction containing tenfold serially diluted genomic DNA; though no effect was observed on Clavibacter-specific primer/probe set. The assay is accurate and has applications at point-of-need diagnostics. This is the first multiplex RPA assay for any plant pathogen.


Assuntos
Clavibacter/genética , Genômica , Técnicas de Amplificação de Ácido Nucleico/métodos , Nucleotidiltransferases/genética , Zea mays/microbiologia , Temperatura Corporal , Simulação por Computador , DNA Bacteriano/genética , Limite de Detecção , Microbiologia , Filogenia , Doenças das Plantas/microbiologia , Reação em Cadeia da Polimerase , Recombinases/genética , Sensibilidade e Especificidade
10.
Mycotoxin Res ; 37(3): 229-240, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34128190

RESUMO

Driven by increasing temperatures and the higher incidences of heat waves during summer, an increased incidence of Aspergillus flavus next to Fusarium verticillioides in European maize can be expected. In the current study, we investigated the interaction between both species. Colonies of A. flavus/F. verticillioides were grown in a single culture, in a dual culture, and in a mixed culture. The growth rate of A. flavus and F. verticillioides grown in a dual or mixed culture with the other species was clearly slower compared to the growth rate in a single culture. Mycotoxin production was in most cases negatively affected by dual or mixed inoculation. In planta, a dual inoculation resulted in reduced lesions of A. flavus, whereas the lesion size and toxin production of F. verticillioides were unaffected in the presence of A. flavus. The lesions as a result of a mixed inoculation were 112% bigger than a single A. flavus inoculation and 9% smaller than a single F. verticillioides inoculation. The fumonisin levels were 17% higher compared to a single inoculation. In case A. flavus was present two days before F. verticillioides, the lesion size of F. verticillioides was 55% smaller compared to a single F. verticillioides inoculation, and fumonisin production was almost completely inhibited. The interaction between A. flavus and F. verticillioides is highly dynamic and depends on the experimental conditions, on the variables measured and on the way they colonize the host, in two inoculation points, simultaneously in one inoculation point, or sequentially one species colonizing an existing lesion made by the other.


Assuntos
Aspergillus flavus/metabolismo , Fusarium/metabolismo , Interações Microbianas , Micotoxinas/análise , Zea mays/microbiologia , Aspergillus flavus/crescimento & desenvolvimento , Fusarium/crescimento & desenvolvimento , Micotoxinas/biossíntese
11.
Mycotoxin Res ; 37(3): 249-263, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34173210

RESUMO

A microcosm study was conducted at two different temperatures under laboratory conditions to investigate the regulatory capacity and the interactive performance of two soil fauna species (Aporrectodea caliginosa, earthworms, and Proisotoma minuta, collembolans) on the reduction of Fusarium toxins in contaminated maize stubbles. Single and mixed species treatments were exposed to artificially infected maize stubbles highly contaminated with the mycotoxins deoxynivalenol (DON) (10,462 µg kg-1) and zearalenone (ZEN) (2,780 µg kg-1) at 17 °C and 25 °C for time periods of 3 and 6 weeks. Immediately after the respective end of incubation, the microcosms were heavily watered to determine the leaching potential of DON and ZEN from contaminated maize stubbles. Maize residues, soil, and eluted water (percolate) samples were analysed for mycotoxin content using liquid chromatography coupled to mass spectrometry. The biomass of introduced earthworms and number of collembolans were monitored to get information about their adaptability to the experimental conditions. While the decline of ZEN was temperature-dependent, but not influenced by faunal activities, a reduction of DON due to faunal impact was observed by trend. In the leaching experiment, 67-82% of the DON content in the residual maize stubbles leached from the plant material by irrigation and was detected in the soil (1.9-3.4 µg kg-1) and in the percolate (12-295 µg L-1). In the case of ZEN, 27-50% of the mycotoxin leached from the residual maize stubbles due to watering but was only occasionally detected in traces in the soil and not found in the percolate. The results clearly reveal a leaching potential of both DON and ZEN, respectively, but a mobilisation with water was only observed for DON. Temperature confirmed to be a key factor, affecting the fate of the mycotoxins in the soil by driving the interaction between different soil fauna members as well as functional and trophic levels within the soil food web.


Assuntos
Fusarium/patogenicidade , Micotoxinas/análise , Temperatura , Tricotecenos/análise , Zea mays/química , Zearalenona/análise , Cromatografia Líquida , Contaminação de Alimentos/análise , Espectrometria de Massas , Solo , Zea mays/microbiologia
12.
Arch Microbiol ; 203(7): 4609-4618, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34165624

RESUMO

This work aims to characterize the arbuscular mycorrhizal association between maize genotypes and the effects of soil physical-chemical attributes on the symbiosis. A preliminary greenhouse assay evaluated five maize landraces and five conventional modern genotypes in non-sterile, low-P soil. Sixty days after sowing, we measured plant height, stem diameter, shoot and root dry biomass, root colonization structures, and shoot P concentration and total accumulation. In a second stage, a 2-year on-farm study evaluated how soil physical-chemical attributes in fields with three plant genotype groups affected the arbuscular mycorrhizal fungal symbiosis in a maize diversity microcenter in Southern Brazil. We collected soil and plant material in farms growing landrace, conventional modern genotypes, or genetically modified (GM) maize. There were five collection points at each group, and we measured mycorrhizal colonization, soil physicochemical attributes, and shoot phosphorus concentration. The greenhouse study showed that genotypes have different growth strategies for root production and shoot growth. No differences in mycorrhizal colonization rates occurred among landraces and modern maize genotypes in the low-P soil. The field study showed that soil and climate conditions had a more marked effect on mycorrhizal root colonization than plant genotype groups (landrace, conventional modern genotypes, or GM maize).


Assuntos
Genótipo , Micorrizas , Raízes de Plantas , Zea mays , Agricultura , Brasil , Micorrizas/fisiologia , Raízes de Plantas/microbiologia , Solo/química , Tempo (Meteorologia) , Zea mays/genética , Zea mays/microbiologia
13.
Toxins (Basel) ; 13(6)2021 05 30.
Artigo em Inglês | MEDLINE | ID: mdl-34070838

RESUMO

This study investigated the impact of deoxynivalenol (DON) from naturally contaminated feed on pig growth, immune status, organ health, brain serotonin (5-Hydroxytryptamine, 5-HT) and behavior. Sixteen individually housed pigs (25.57 ± 0.98 kg, age 9 weeks) were randomly allotted to two dietary treatments: without DON (CON) or with 3.8 mg/kg of DON (MT). Pigs were pair-fed to eliminate differences in feed intake (equal tryptophan (Trp) intake). Pigs fed CON received a daily ration based on the ad libitum feed consumption of their MT pair-mate. Performance was determined over 21 days and blood collected for immunological and oxidative stress parameters. Behavior was recorded for 12 h on days 0, 7, 14 and 21. After 21 days, pigs were euthanized to collect tissues for immune parameters, gut morphology and brain serotonin levels. Overall, pigs fed MT had greater weight gain compared with CON. Immunological and oxidative stress parameters were unaffected, but pigs fed MT had reduced villus height, crypt depth and villus-to-crypt ratio in the jejunum. Pigs consuming MT had reduced concentration of 5-HT and increased 5-HT turnover in the hypothalamus. Mycotoxin-fed pigs spent more time lying and sitting, and less time standing and drinking. In conclusion, consumption of DON impacted gastrointestinal tract structure, altered behavior and changed Trp metabolism through increasing 5-HT turnover in hypothalamus.


Assuntos
Comportamento Animal/efeitos dos fármacos , Encéfalo/metabolismo , Contaminação de Alimentos , Trato Gastrointestinal/efeitos dos fármacos , Tricotecenos/toxicidade , Triptofano/metabolismo , Zea mays/microbiologia , Ração Animal , Animais , Encéfalo/efeitos dos fármacos , Trato Gastrointestinal/imunologia , Masculino , Estresse Oxidativo , Condicionamento Físico Animal , Suínos
14.
Toxins (Basel) ; 13(6)2021 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-34071223

RESUMO

Resistance against infection by the fungus Aspergillus flavus Link in commercial maize (Zea mays L.) is the topic of many studies, but few studies have investigated the effects of A. flavus infection on gene expression levels in ear kernels. A crucial component of gene expression profiling by RT-qPCR is having a reliable set of reference genes that show relatively constant expression across the treatments and phenotypes under study. Currently, however, there is no published information on reference genes suitable for measuring changes in kernel gene expression levels after infection with A. flavus. Thus, in this study, six candidate reference genes (ACT1, ß-Tub2, eIF4A2, TATA, EFIα, and GAPDH) were evaluated and ranked according to their expression stability. The genes were amplified from first-strand cDNA samples synthesized from kernels of two susceptible and two resistant maize lines that were either inoculated with A. flavus or water or not inoculated. Three software packages were used to calculate and rank the stability of expression for these genesgeNorm, NormFinder, and BestKeeper. The analysis revealed that the most stable genes to normalize expression levels from maize kernels responding to A. flavus inoculation and wounding were ACT1, EFIα, and eIF4A2.


Assuntos
Aspergillus flavus/fisiologia , Reação em Cadeia da Polimerase em Tempo Real/métodos , Zea mays/genética , Zea mays/microbiologia , Perfilação da Expressão Gênica
15.
Sci Rep ; 11(1): 13215, 2021 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-34168223

RESUMO

In corn/maize, silks emerging from cobs capture pollen, and transmit resident sperm nuclei to eggs. There are > 20 million silks per U.S. maize acre. Fungal pathogens invade developing grain using silk channels, including Fusarium graminearum (Fg, temperate environments) and devastating carcinogen-producers (Africa/tropics). Fg contaminates cereal grains with mycotoxins, in particular Deoxynivalenol (DON), known for adverse health effects on humans and livestock. Fitness selection should promote defensive/healthy silks. Here, we report that maize silks, known as styles in other plants, possess complex and dynamic microbiomes at the critical pollen-fungal transmission interval (henceforth: transmitting style microbiome, TSM). Diverse maize genotypes were field-grown in two trial years. MiSeq 16S rRNA gene sequencing of 328 open-pollinated silk samples (healthy/Fg-infected) revealed that the TSM contains > 5000 taxa spanning the prokaryotic tree of life (47 phyla/1300 genera), including nitrogen-fixers. The TSM of silk tip tissue displayed seasonal responsiveness, but possessed a reproducible core of 7-11 MiSeq-amplicon sequence variants (ASVs) dominated by a single Pantoea MiSeq-taxon (15-26% of sequence-counts). Fg-infection collapsed TSM diversity and disturbed predicted metabolic functionality, but doubled overall microbiome size/counts, primarily by elevating 7-25 MiSeq-ASVs, suggestive of a selective microbiome response against infection. This study establishes the maize silk as a model for fundamental/applied research of plant reproductive microbiomes.


Assuntos
Microbiota/genética , Seda/metabolismo , Zea mays/microbiologia , África , Fusarium/genética , Micotoxinas/genética , Pólen/microbiologia , Polinização/fisiologia , RNA Ribossômico 16S/genética
16.
Sci Rep ; 11(1): 13092, 2021 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-34158574

RESUMO

Microorganisms are often applied as biofertilizer to crops to stimulate plant growth, increase yields and reduce inorganic N application. The survival and proliferation of these allochthonous microorganisms in soil is a necessary requisite for them to promote plant growth. We applied a sterilized or unsterilized not commercialized bacterial consortium mixed with cow manure leachate used by a farmer as biofertilizer to maize (Zea mays L.) in a greenhouse experiment, while maize development and the bacterial community structure was determined just before the biofertilizer was applied a first time (day 44), after three applications (day 89) and after six application at the end of the experiment (day 130). Application of sterilized or unsterilized biofertilizer with pH 4.3 and 864 mg NH4+-N kg-1 had no significant effect on maize growth. The application of the biofertilizer dominated by Lactobacillus (relative abundance 11.90%) or the sterilized biofertilizer changed the relative abundance of a limited number of bacterial groups, i.e. Delftia, Halomonas, Lactobacillus and Stenotrophomonas, without altering significantly the bacterial community structure. Cultivation of maize, however, affected significantly the bacterial community structure, which showed large significant variations over time in the cultivated and uncultivated soil. It was concluded that the bacteria applied as a biofertilizer had only a limited effect on the relative abundance of these groups in uncultivated or soil cultivated with maize.


Assuntos
Fertilizantes/microbiologia , Microbiota/fisiologia , Zea mays/microbiologia , Bactérias , Produtos Agrícolas , Fertilizantes/análise , Esterco , Desenvolvimento Vegetal , Solo/química , Microbiologia do Solo
17.
PLoS One ; 16(6): e0252823, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34129651

RESUMO

The reduction of the use chemical pesticides in agriculture is gaining importance as an objective of decision-makers in both politics and economics. Consequently, the development of technically efficient and economically affordable alternatives as, e.g., biological control agents or practices is highly solicited. Crown gall disease of dicotyledonous plants is caused by ubiquitous soil borne pathogenic bacteria of the Agrobacterium tumefaciens species complex, that comprises the species Agrobacterium fabrum and represents a globally relevant plant protection problem. Within the framework of a screening program for bacterial Agrobacterium antagonists a total of 14 strains were isolated from Tunisian soil samples and assayed for antagonistic activity against pathogenic agrobacteria. One particularly promising isolate, termed strain MBY2, was studied more in depth. Using a Multilocus Sequence Analysis (MLSA) approach, the isolate was assigned to the taxonomic species Bacillus velezensis. Strain MBY2 was shown to display antagonistic effects against the pathogenic A. fabrum strain C58 in vitro and to significantly decrease pathogen populations under sterile and non-sterile soil conditions as well as in the rhizosphere of maize and, to a lower extent, tomato plants. Moreover, the ability of B. velezensis MBY2 to reduce C58-induced gall development has been demonstrated in vivo on stems of tomato and almond plants. The present study describes B. velezensis MBY2 as a newly discovered strain holding potential as a biological agent for crown gall disease management.


Assuntos
Agrobacterium/fisiologia , Antibiose/fisiologia , Bacillus/fisiologia , Lycopersicon esculentum/microbiologia , Tumores de Planta/microbiologia , Zea mays/microbiologia , Bacillus/classificação , Bacillus/genética , Agentes de Controle Biológico/farmacologia , Contenção de Riscos Biológicos/métodos , Viabilidade Microbiana/efeitos dos fármacos , Filogenia , Rizosfera , Microbiologia do Solo
18.
Fungal Genet Biol ; 152: 103565, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33991665

RESUMO

Fungal dimorphism is a phenomenon by which a fungus can grow both as a yeast form and a hyphal form. It is frequently related to pathogenicity as different growth forms are more suitable for different functions during a life cycle. Among dimorphic plant pathogens, the corn smut fungus Ustilago maydis serves as a model organism to understand fungal dimorphism and its effect on pathogenicity. However, there is a lack of data on whether mechanisms elucidated from model species are broadly applicable to other fungi. In this study, two non-model plant-associated species in the smut fungus subphylum (Ustilaginomycotina), Tilletiopsis washingtonensis and Meira miltonrushii, were selected to compare dimorphic mechanisms in these to those in U. maydis. We sequenced transcriptomic profiles during both yeast and hyphal growth in these two species using Tween40, a lipid mimic, as a trigger for hyphal growth. We then compared our data with previously published data from U. maydis and a fourth but unrelated dimorphic phytopathogen, Ophiostoma novo-ulmi. Comparative transcriptomics was performed to identify common genes upregulated during hyphal growth in all four dimorphic species. Intriguingly, T. washingtonensis shares the least similarities of transcriptomic alteration (hyphal growth versus yeast growth) with the others, although it is closely related to M. miltonrushii and U. maydis. This suggests that phylogenetic relatedness is not correlated with transcriptomic similarity under the same biological phenomenon. Among commonly expressed genes in the four species, genes in cell energy production and conversion, amino acid transport and metabolism and cytoskeleton are significantly enriched. Considering dimorphism genes characterized in U. maydis, as well as hyphal tip-associated genes from the literature, we found only genes encoding the cell end marker Tea4/TeaC and the kinesin motor protein Kin3 concordantly expressed in all four species. This suggests a divergence in species-specific mechanisms for dimorphic transition and hyphal growth.


Assuntos
Fungos/genética , Fungos/metabolismo , Hifas/crescimento & desenvolvimento , Hifas/genética , Hifas/metabolismo , Plantas/microbiologia , Transcriptoma , Basidiomycota/genética , Fungos/classificação , Fungos/crescimento & desenvolvimento , Ophiostoma , Filogenia , Ustilaginales , Ustilago/genética , Ustilago/crescimento & desenvolvimento , Ustilago/metabolismo , Leveduras , Zea mays/microbiologia
19.
Nat Commun ; 12(1): 2576, 2021 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-33958593

RESUMO

Nitric oxide (NO) is a diffusible signaling molecule that modulates animal and plant immune responses. In addition, reactive nitrogen species derived from NO can display antimicrobial activities by reacting with microbial cellular components, leading to nitrosative stress (NS) in pathogens. Here, we identify FgAreB as a regulator of the NS response in Fusarium graminearum, a fungal pathogen of cereal crops. FgAreB serves as a pioneer transcription factor for recruitment of the chromatin-remodeling complex SWI/SNF at the promoters of genes involved in the NS response, thus promoting their transcription. FgAreB plays important roles in fungal infection and growth. Furthermore, we show that a transcription repressor (FgIxr1) competes with the SWI/SNF complex for FgAreB binding, and negatively regulates the NS response. NS, in turn, promotes the degradation of FgIxr1, thus enhancing the recruitment of the SWI/SNF complex by FgAreB.


Assuntos
Montagem e Desmontagem da Cromatina/genética , Proteínas Cromossômicas não Histona/metabolismo , Fusarium/metabolismo , Fatores de Transcrição GATA/metabolismo , Regulação Fúngica da Expressão Gênica/genética , Doenças das Plantas/microbiologia , Proteína SMARCB1/metabolismo , Fatores de Transcrição/metabolismo , Imunoprecipitação da Cromatina , Proteínas Cromossômicas não Histona/genética , Fusarium/genética , Fusarium/patogenicidade , Fatores de Transcrição GATA/genética , Proteínas de Grupo de Alta Mobilidade/genética , Proteínas de Grupo de Alta Mobilidade/metabolismo , Óxido Nítrico/metabolismo , Estresse Nitrosativo , Proteína SMARCB1/genética , Fatores de Transcrição/genética , Triticum/microbiologia , Zea mays/microbiologia
20.
Arch Virol ; 166(8): 2315-2319, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34028604

RESUMO

A putative polymycovirus tentatively named "Setosphaeria turcica polymycovirus 1" (StPmV1) was discovered in the phytopathogenic fungus Setosphaeria turcica. StPmV1 has a genome comprising five double-stranded RNAs (dsRNAs). dsRNA1, 2, and 3 each encode a protein sharing significant similarity but lower than 64% sequence identity to the corresponding proteins of other polymycoviruses. dsRNA4 and 5 each encode a protein with a sequence that is not conserved among polymycoviruses. However, the protein encoded by dsRNA4 is rich in proline (P), alanine (A), and serine (S) residues, which is a feature shared by the so-called PAS-rich proteins encoded by all polymycoviruses. Phylogeny reconstruction using the RNA-dependent RNA polymerase (RdRp) sequences of accepted or putative polymycoviruses revealed that StPmV1 is most closely related to Plasmopara viticola lesion associated polymycovirus 1 (PvaPolymyco1), a putative polymycovirus recovered from the phytopathogenic oomycetes Plasmopara viticola. These data suggest that StPmV1 may represent a novel species of the genus Polymycovirus, family Polymycoviridae. To our knowledge, this is the first polymycovirus reported from S. turcica.


Assuntos
Ascomicetos/virologia , Micovírus/classificação , RNA de Cadeia Dupla/genética , Sequenciamento Completo do Genoma/métodos , Composição de Bases , Micovírus/genética , Micovírus/isolamento & purificação , Tamanho do Genoma , Fases de Leitura Aberta , Filogenia , Folhas de Planta/microbiologia , RNA Fúngico/genética , Zea mays/microbiologia
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