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1.
Int J Nanomedicine ; 15: 7143-7153, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33061372

RESUMO

Introduction: Tobacco mosaic virus-based nanoparticles (TMV VNPs) were previously shown to promote osteogenic differentiation in vitro. This study aims to investigate whether and how TMV VNPs impact on osteoclastogenesis in vitro and bone injury healing in vivo. Methods: Raw264.7 cells were cultured in osteoclastogenic medium in culture plates coated with or without TMV and TMV-RGD1 VNPs, followed by TRAP staining, RT-qPCR and WB assessing expression of osteoclastogenic marker genes, and immunofluorescence assessing NF-κB activation. TMV and TMV-RGD1-modified hyaluronic acid hydrogel were used to treat mouse tibial bone injury. Bone injury healing was checked by micro-CT and Masson staining. Results: TMV and TMV-RGD1 VNPs significantly inhibited osteoclast differentiation and downregulated the expression of osteoclastogenic marker genes Ctr, Ctsk, Mmp-9, Rank, and Trap. Moreover, TMV and TMV-RGD1 VNPs inhibited NF-κB p65 phosphorylation and nuclear translocation, as well as activation of mTOR/AKT signaling pathway. TMV and TMV-RGD1-modified HA hydrogel strongly promoted mouse tibial bone injury with increased bone mass compared to plain HA hydrogel. The amount of osteoclasts was significantly reduced in TMV and TMV-RGD1 treated mice. TMV-RGD1 was more effective than TMV in inhibiting osteoclast differentiation and promoting bone injury repair. Discussion: These data demonstrated the great potential of TMV VNPs to be developed into biomaterial for bone injury repair or replacement.


Assuntos
Nanopartículas/química , Osteogênese , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , Vírus do Mosaico do Tabaco/fisiologia , Animais , Osso e Ossos/patologia , Diferenciação Celular/efeitos dos fármacos , Camundongos , NF-kappa B/metabolismo , Nanopartículas/ultraestrutura , Osteoclastos/efeitos dos fármacos , Osteoclastos/patologia , Fosforilação , Proteínas Proto-Oncogênicas c-akt/metabolismo , Células RAW 264.7 , Ratos , Transdução de Sinais/efeitos dos fármacos , Tíbia/patologia , Cicatrização
2.
Proc Natl Acad Sci U S A ; 117(7): 3779-3788, 2020 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-32015104

RESUMO

Plants and fungi are closely associated through parasitic or symbiotic relationships in which bidirectional exchanges of cellular contents occur. Recently, a plant virus was shown to be transmitted from a plant to a fungus, but it is unknown whether fungal viruses can also cross host barriers and spread to plants. In this study, we investigated the infectivity of Cryphonectria hypovirus 1 (CHV1, family Hypoviridae), a capsidless, positive-sense (+), single-stranded RNA (ssRNA) fungal virus in a model plant, Nicotiana tabacum CHV1 replicated in mechanically inoculated leaves but did not spread systemically, but coinoculation with an unrelated plant (+)ssRNA virus, tobacco mosaic virus (TMV, family Virgaviridae), or other plant RNA viruses, enabled CHV1 to systemically infect the plant. Likewise, CHV1 systemically infected transgenic plants expressing the TMV movement protein, and coinfection with TMV further enhanced CHV1 accumulation in these plants. Conversely, CHV1 infection increased TMV accumulation when TMV was introduced into a plant pathogenic fungus, Fusarium graminearum In the in planta F. graminearum inoculation experiment, we demonstrated that TMV infection of either the plant or the fungus enabled the horizontal transfer of CHV1 from the fungus to the plant, whereas CHV1 infection enhanced fungal acquisition of TMV. Our results demonstrate two-way facilitative interactions between the plant and fungal viruses that promote cross-kingdom virus infections and suggest the presence of plant-fungal-mediated routes for dissemination of fungal and plant viruses in nature.


Assuntos
Micovírus/fisiologia , Fusarium/virologia , Doenças das Plantas/virologia , Vírus de Plantas/fisiologia , Vírus do Mosaico do Tabaco/fisiologia , Tabaco/virologia , Fusarium/fisiologia
3.
J Agric Food Chem ; 68(4): 975-981, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31891504

RESUMO

In this study, a series of coumarin derivatives containing dithioacetals were synthesized, characterized, and assessed for their anti-tobacco mosaic virus (TMV) activities. Biological tests showed that most of the title compounds exhibited significant anti-TMV biological activities; in particular, compound b21 showed good inactivating activity anti-TMV, with an EC50 of 54.2 mg/L, superior to that of ribavirin (134.2 mg/L). Transmission electron microscopy analyses showed that compound 21 severely ruptured TMV particles. The interaction of compound b21 with TMV coat protein (TMV CP) was investigated using microscale thermophoresis and molecular docking. Compound b21 exhibited a strong binding ability to TMV CP, with a value of 2.9 µM, superior to ribavirin.


Assuntos
Antivirais/síntese química , Antivirais/farmacologia , Cumarínicos/síntese química , Cumarínicos/farmacologia , Antivirais/química , Proteínas do Capsídeo/química , Proteínas do Capsídeo/metabolismo , Cumarínicos/química , Desenho de Fármacos , Testes de Sensibilidade Microbiana , Simulação de Acoplamento Molecular , Relação Estrutura-Atividade , Vírus do Mosaico do Tabaco/efeitos dos fármacos , Vírus do Mosaico do Tabaco/fisiologia
4.
J Agric Food Chem ; 68(2): 471-484, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31841334

RESUMO

Plant diseases seriously affect crop yield and quality and are difficult to control. Marine natural products (MNPs) have become an important source of drug candidates with new biological mechanisms. Marine natural product essramycin (1) was found to have good anti-tobacco mosaic virus (TMV) and anti-phytopathogenic fungus activities for the first time. A series of essramycin derivatives were designed, synthesized, and evaluated for their bioactivity. Most of these compounds exhibited antiviral effects that are greater than that of the control ribavirin. Compounds 7e and 8f displayed antiviral activities that are greater than that of ningnanmycin (the most widely used antiviral agent at present), thus emerging as novel antiviral lead compounds. As the lead compound, 7e was selected for further antiviral mechanism research. The results indicated that 7e could inhibit virus assembly and promote 20S disk protein aggregation. Fungicidal activity tests against 14 kinds of phytopathogenic fungi revealed that essramycin analogues displayed broad-spectrum fungicidal activities. Compound 5b displayed more than 50% inhibition rate against most of the 14 kinds of phytopathogenic fungi at 50 µg/mL. The current research lays a solid foundation for the application of essramycin alkaloids in crop protection.


Assuntos
Alcaloides/química , Antivirais/química , Fungicidas Industriais/química , Pirimidinonas/química , Vírus do Mosaico do Tabaco/efeitos dos fármacos , Triazóis/química , Alcaloides/farmacologia , Antivirais/farmacologia , Fungos/efeitos dos fármacos , Fungos/fisiologia , Fungicidas Industriais/farmacologia , Estrutura Molecular , Doenças das Plantas/microbiologia , Pirimidinonas/farmacologia , Relação Estrutura-Atividade , Vírus do Mosaico do Tabaco/fisiologia , Triazóis/farmacologia , Montagem de Vírus/efeitos dos fármacos
5.
Phytopathology ; 110(1): 194-205, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31502520

RESUMO

Tobacco mosaic virus (TMV) is an extensively studied RNA virus known to infect tobacco (Nicotiana tabacum) and other solanaceous crops. TMV has been classified as a seedborne virus in tobacco, with infection of developing seedlings thought to occur from contact with the TMV-infected seed coat. The mechanism of TMV transmission through seed was studied in seed of the K 326 cultivar of flue-cured tobacco. Cross pollinations were performed to determine the effect of parental tissue on TMV infection in seed. Dissection of individual tobacco seeds into seed coat, endosperm, and embryo was performed to determine TMV location within a seed, while germination tests and separation of the developing seedling into seed coat, roots, and cotyledons were conducted to estimate the percent transmission of TMV. A reverse-transcriptase quantitative PCR (RT-qPCR) assay was developed and used to determine TMV concentrations in individual seed harvested from pods that formed on plants from TMV-infected and noninfected crosses. The results showed maternal transmission of TMV to tobacco seed and seedlings that developed from infected seed, not paternal transmission. RT-qPCR and endpoint PCR assays were also conducted on the separated seed coat, endosperm, and embryo of individual seed and separated cotyledons, roots, and seed coats of individual seedlings that developed from infected tobacco seed to identify the location of the virus in the seed and the subsequent path the virus takes to infect the developing seedling. RT-qPCR and endpoint PCR assay results showed evidence of TMV infection in the endosperm and embryo, as well as in the developing seedling roots and cotyledons within 10 days of initiating seed germination. To our knowledge, this is the first report of TMV being detected in embryos of tobacco seed, demonstrating that TMV is seedborne and seed-transmitted in flue-cured tobacco.


Assuntos
Reação em Cadeia da Polimerase em Tempo Real , Vírus do Mosaico do Tabaco , Tabaco , Doenças das Plantas/virologia , Plântula/virologia , Sementes/virologia , Tabaco/virologia , Vírus do Mosaico do Tabaco/genética , Vírus do Mosaico do Tabaco/fisiologia
6.
Molecules ; 25(1)2019 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-31878172

RESUMO

The coumarin compound of osthole was extracted from Cnidium monnieri and identified by LC-MS and 1H- and 13C-NMR. Osthole was tested for anti-virus activity against tobacco mosaic virus (TMV) using the half-leaf method. The results showed that stronger antiviral activity on TMV infection appeared in Nicotiana glutinosa than that of eugenol and ningnanmycin, with inhibitory, protective, and curative effects of 72.57%, 70.26%, and 61.97%, respectively. Through observation of the TMV particles, we found that osthole could directly affect the viral particles. Correspondingly, the level of coat protein detected by Western blot was significantly reduced when the concentrations of osthole increased in tested plants compared to that of the control. These results suggest that osthole has anti-TMV activity and may be used as a biological reagent to control the plant virus in the half-leaf method.


Assuntos
Cnidium/química , Cumarínicos/farmacologia , Doenças das Plantas/terapia , Doenças das Plantas/virologia , Vírus do Mosaico do Tabaco/efeitos dos fármacos , Vírus do Mosaico do Tabaco/fisiologia , Tabaco/virologia , Antivirais/farmacologia , Proteínas do Capsídeo/metabolismo , Cumarínicos/química , Cinética , Vírus do Mosaico do Tabaco/ultraestrutura , Vírion/efeitos dos fármacos , Vírion/ultraestrutura
7.
Viruses ; 11(9)2019 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-31484426

RESUMO

Ningnanmycin (NNM) belongs to microbial pesticides that display comprehensive antiviral activity against plant viruses. NNM treatment has been shown to efficiently delay or suppress the disease symptoms caused by tobacco mosaic virus (TMV) infection in local-inoculated or systemic-uninoculated tobacco leaves, respectively. However, the underlying molecular mechanism of NNM-mediated antiviral activity remains to be further elucidated. In this study, 414 differentially expressed genes (DEGs), including 383 which were up-regulated and 31 down-regulated, caused by NNM treatment in TMV-infected BY-2 protoplasts, were discovered by RNA-seq. In addition, KEGG analysis indicated significant enrichment of DEGs in the plant-pathogen interaction and MAPK signaling pathway. The up-regulated expression of crucial DEGs, including defense-responsive genes, such as the receptor-like kinase FLS2, RLK1, and the mitogen-activated protein kinase kinase kinase MAPKKK, calcium signaling genes, such as the calcium-binding protein CML19, as well as phytohormone responsive genes, such as the WRKY transcription factors WRKY40 and WRKY70, were confirmed by RT-qPCR. These findings provided valuable insights into the antiviral mechanisms of NNM, which indicated that the agent induces tobacco systemic resistance against TMV via activating multiple plant defense signaling pathways.


Assuntos
Antivirais/farmacologia , Citidina/análogos & derivados , Doenças das Plantas/imunologia , Vírus do Mosaico do Tabaco/efeitos dos fármacos , Citidina/farmacologia , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Doenças das Plantas/virologia , Reguladores de Crescimento de Planta/metabolismo , Imunidade Vegetal/efeitos dos fármacos , Imunidade Vegetal/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Protoplastos/virologia , Transdução de Sinais/efeitos dos fármacos , Tabaco/virologia , Vírus do Mosaico do Tabaco/fisiologia
8.
EMBO Rep ; 20(11): e48451, 2019 11 05.
Artigo em Inglês | MEDLINE | ID: mdl-31535454

RESUMO

Stable capsid structures of viruses protect viral RNA while they also require controlled disassembly for releasing the viral genome in the host cell. A detailed understanding of viral disassembly processes and the involved structural switches is still lacking. This process has been extensively studied using tobacco mosaic virus (TMV), and carboxylate interactions are assumed to play a critical part in this process. Here, we present two cryo-EM structures of the helical TMV assembly at 2.0 and 1.9 Å resolution in conditions of high Ca2+ concentration at low pH and in water. Based on our atomic models, we identify the conformational details of the disassembly switch mechanism: In high Ca2+ /acidic pH environment, the virion is stabilized between neighboring subunits through carboxyl groups E95 and E97 in close proximity to a Ca2+ binding site that is shared between two subunits. Upon increase in pH and lower Ca2+ levels, mutual repulsion of the E95/E97 pair and Ca2+ removal destabilize the network of interactions between adjacent subunits at lower radius and release the switch for viral disassembly.


Assuntos
Modelos Moleculares , Vírus do Mosaico do Tabaco/fisiologia , Montagem de Vírus , Cálcio/química , Capsídeo/química , Concentração de Íons de Hidrogênio , Fenótipo , Reprodutibilidade dos Testes , Vírion
9.
J Agric Food Chem ; 67(36): 10000-10009, 2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31442045

RESUMO

Improving plant resistance against systemic diseases remains a challenging research topic. In this study, we developed a dual-action pesticide-loaded hydrogel with the capacity to significantly induce plant resistance against tobacco mosaic virus (TMV) infection and promote plant growth. We produced an alginate-lentinan-amino-oligosaccharide hydrogel (ALA-hydrogel) by coating the surface of an alginate-lentinan drug-loaded hydrogel (AL-hydrogel) with amino-oligosaccharide using electrostatic action. We determined the formation of the amino-oligosaccharide film using various approaches, including Fourier transform infrared spectrometry, the ζ potential test, scanning electron microscopy, and elemental analysis. It was found that the ALA-hydrogel exhibited stable sustained-release activity, and the release time was significantly longer than that of the AL-hydrogel. In addition, we demonstrated that the ALA-hydrogel was able to continuously and strongly induce plant resistance against TMV and increase the release of calcium ions to promote Nicotiana benthamiana growth. Meanwhile, the ALA-hydrogel maintained an extremely high safety to organisms. Our findings provide an alternative to the traditional approach of applying pesticide for controlling plant viral diseases. In the future, this hydrogel with the simple synthesis method, green synthetic materials, and its efficiency in the induction of plant resistance will attract increasing attention and have good potential to be employed in plant protection and agricultural production.


Assuntos
Antivirais/química , Preparações de Ação Retardada/farmacologia , Portadores de Fármacos/química , Lentinano/química , Lentinano/farmacologia , Doenças das Plantas/virologia , Vírus do Mosaico do Tabaco/fisiologia , Tabaco/virologia , Alginatos/química , Antivirais/farmacologia , Preparações de Ação Retardada/química , Resistência à Doença , Hidrogéis/química , Doenças das Plantas/imunologia , Tabaco/imunologia
10.
Genes (Basel) ; 10(7)2019 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-31336929

RESUMO

RNAi (RNA interference) is an important defense response against virus infection in plants. The core machinery of the RNAi pathway in plants include DCL (Dicer Like), AGO (Argonaute) and RdRp (RNA dependent RNA polymerase). Although involvement of these RNAi components in virus infection responses was demonstrated in Arabidopsis thaliana, their contribution to antiviral immunity in Nicotiana benthamiana, a model plant for plant-pathogen interaction studies, is not well understood. In this study, we investigated the role of N. benthamiana NbAGO2 gene against TMV (Tomato mosaic virus) infection. Silencing of NbAGO2 by transient expression of an hpRNA construct recovered GFP (Green fluorescent protein) expression in GFP-silenced plant, demonstrating that NbAGO2 participated in RNAi process in N. benthamiana. Expression of NbAGO2 was transcriptionally induced by both MeSA (Methylsalicylate acid) treatment and TMV infection. Down-regulation of NbAGO2 gene by amiR-NbAGO2 transient expression compromised plant resistance against TMV infection. Inhibition of endogenous miR403a, a predicted regulatory microRNA of NbAGO2, reduced TMV infection. Our study provides evidence for the antiviral role of NbAGO2 against a Tobamovirus family virus TMV in N. benthamiana, and SA (Salicylic acid) mediates this by induction of NbAGO2 expression upon TMV infection. Our data also highlighted that miR403a was involved in TMV defense by regulation of target NbAGO2 gene in N. Benthamiana.


Assuntos
Proteínas Argonauta/genética , Genes de Plantas , Doenças das Plantas/virologia , Ácido Salicílico/farmacocinética , Vírus do Mosaico do Tabaco , Tabaco/virologia , Proteínas Argonauta/imunologia , Regulação para Baixo , Regulação da Expressão Gênica de Plantas , Inativação Gênica , MicroRNAs , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Interferência de RNA , RNA de Plantas , Tabaco/genética , Tabaco/imunologia , Vírus do Mosaico do Tabaco/fisiologia
11.
J Agric Food Chem ; 67(27): 7738-7747, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31199650

RESUMO

Cytosinpeptidemycin (CytPM) is a microbial pesticide that displayed broad-spectrum antiviral activity against various plant viruses. However, the molecular mechanism underlying antiviral activity of CytPM is poorly understood. In this study, the results demonstrated that CytPM could effectively delay the systemic infection of tobacco mosaic virus (TMV) in Nicotiana benthamiana and significantly inhibit the viral accumulation in tobacco BY-2 protoplasts. Results of RNA-seq indicated that 210 and 120 differential expressed genes (DEGs) were significantly up- and down-regulated after CytPM treatment in BY-2 protoplasts, respectively. In addition, KEGG analysis indicated that various DEGs were involved in endoplasmic reticulum (ER) protein processing, suggesting a possible correlation between ER homeostasis and virus resistance. RT-qPCR was performed to validate the gene expression of crucial DEGs related with defense, stress responses, signaling transduction, and phytohormone, which were consistent with results of RNA-seq. Our works provided valuable insights into the antiviral mechanism of CytPM that induced host resistance to viral infection.


Assuntos
Antivirais , Citosina/análogos & derivados , Resistência à Doença/genética , Doenças das Plantas/prevenção & controle , Vírus do Mosaico do Tabaco/fisiologia , Tabaco/virologia , Citosina/farmacologia , Resistência à Doença/efeitos dos fármacos , Expressão Gênica , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Interações Hospedeiro-Patógeno/efeitos dos fármacos , Interações Hospedeiro-Patógeno/genética , Doenças das Plantas/virologia , Reguladores de Crescimento de Planta/genética , Protoplastos/efeitos dos fármacos , Protoplastos/virologia , Transdução de Sinais/efeitos dos fármacos , Estresse Fisiológico/efeitos dos fármacos , Estresse Fisiológico/genética , Tabaco/genética , Vírus do Mosaico do Tabaco/efeitos dos fármacos , Vírus do Mosaico do Tabaco/patogenicidade
12.
Plant J ; 100(1): 20-37, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31124249

RESUMO

Enzyme promiscuity, a common property of many uridine diphosphate sugar-dependent glycosyltransferases (UGTs) that convert small molecules, significantly hinders the identification of natural substrates and therefore the characterization of the physiological role of enzymes. In this paper we present a simple but effective strategy to identify endogenous substrates of plant UGTs using LC-MS-guided targeted glycoside analysis of transgenic plants. We successfully identified natural substrates of two promiscuous Nicotiana benthamiana UGTs (NbUGT73A24 and NbUGT73A25), orthologues of pathogen-induced tobacco UGT (TOGT) from Nicotiana tabacum, which is involved in the hypersensitive reaction. While in N. tabacum, TOGT glucosylated scopoletin after treatment with salicylate, fungal elicitors and the tobacco mosaic virus, NbUGT73A24 and NbUGT73A25 produced glucosides of phytoalexin N-feruloyl tyramine, which may strengthen cell walls to prevent the intrusion of pathogens, and flavonols after agroinfiltration of the corresponding genes in N. benthamiana. Enzymatic glucosylation of fractions of a physiological aglycone library confirmed the biological substrates of UGTs. In addition, overexpression of both genes in N. benthamiana produced clear lesions on the leaves and led to a significantly reduced content of pathogen-induced plant metabolites such as phenylalanine and tryptophan. Our results revealed some additional biological functions of TOGT enzymes and indicated a multifunctional role of UGTs in plant resistance.


Assuntos
Ácidos Cumáricos/metabolismo , Glucose/metabolismo , Glicosiltransferases/genética , Doenças das Plantas/genética , Proteínas de Plantas/genética , Sesquiterpenos/metabolismo , Tabaco/genética , Tiramina/análogos & derivados , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica de Plantas , Glicosídeos/metabolismo , Glicosilação , Glicosiltransferases/metabolismo , Doenças das Plantas/virologia , Folhas de Planta/genética , Folhas de Planta/metabolismo , Folhas de Planta/virologia , Proteínas de Plantas/metabolismo , Especificidade por Substrato , Tabaco/metabolismo , Tabaco/virologia , Vírus do Mosaico do Tabaco/fisiologia , Tiramina/metabolismo
13.
Planta ; 249(6): 1811-1822, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30840177

RESUMO

MAIN CONCLUSION: This study shows that NgRBP suppresses both local and systemic RNA silencing induced by sense- or double-stranded RNA, and the RNA binding activity is essential for its function. To counteract host defence, many plant viruses encode viral suppressors of RNA silencing targeting various stages of RNA silencing. There is increasing evidence that the plants also encode endogenous suppressors of RNA silencing (ESR) to regulate this pathway. In this study, using Agrobacterium infiltration assays, we characterized NgRBP, a glycine-rich RNA-binding protein from Nicotiana glutinosa, as an ESR. Our results indicated that NgRBP suppressed both local and systemic RNA silencing induced by sense- or double-stranded RNA. We also demonstrated that NgRBP could promote Potato Virus X (PVX) infection in N. benthamiana. NgRBP knockdown by virus-induced gene silencing enhanced PVX and Cucumber mosaic virus resistance in N. glutinosa. RNA immunoprecipitation and electrophoretic mobility shift assays showed that NgRBP bound to GFP mRNA, dsRNA rather than siRNA. These findings provide the evidence that NgRBP acts as an ESR and the RNA affinity of NgRBP plays the key role in its ESR activity. NgRBP responds to multiple signals such as ABA, MeJA, SA, and Tobacco mosaic virus infection. Therefore, it could participate in the regulation of gene expression under specific conditions.


Assuntos
Doenças das Plantas/virologia , Interferência de RNA , RNA Interferente Pequeno/genética , Proteínas de Ligação a RNA/metabolismo , Tabaco/genética , Agrobacterium , Sequência de Aminoácidos , Arginina , Cucumovirus/fisiologia , Genes Reporter , Filogenia , Folhas de Planta/genética , Folhas de Planta/virologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteínas de Ligação a RNA/genética , Alinhamento de Sequência , Tabaco/virologia , Vírus do Mosaico do Tabaco/fisiologia
14.
Sci Rep ; 9(1): 2657, 2019 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-30804453

RESUMO

RNA interference (RNAi) is a sequence identity-dependent RNA degradation mechanism conserved in eukaryotic organisms. One of the roles of RNAi is as a defense system against viral infections, which has been demonstrated in filamentous fungi but not in oomycetes. We investigated the virus-RNAi interplay in the oomycete Phytophthora infestans using a crucifer-infecting strain of the plant virus tobacco mosaic virus (TMVcr) and its derivative TMVcr-Δ122 that is mutated in the sequence of the p122 replicase subunit and thus inhibited in RNA suppression activity. In this study we provide evidence that replication of TMVcr-Δ122 but not of TMVcr was impaired in P. infestans as well as in tobacco plants used as positive control. The interference was associated with induction of high transcription of dicer-like genes Pidcl2 and NtDCL2 and of RNA-dependent-RNA-polymerase Pirdr1 and NtRDR1 in P. infestans and tobacco, respectively. These high transcription levels suggest an RNAi-based response that TMVcr-Δ122 mutant was not able to suppress. Taken altogether, results of this study demonstrated that an antiviral silencing activity operates also in P. infestans and that a plant virus could be a simple and feasible tool for functional studies also in oomycetes.


Assuntos
Interações Hospedeiro-Patógeno , Phytophthora infestans/genética , Phytophthora infestans/virologia , Interferência de RNA , Vírus do Mosaico do Tabaco/fisiologia , Regulação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Inativação Gênica , Genes Reporter , Interações Hospedeiro-Patógeno/genética , Fenótipo , Doenças das Plantas/genética , Doenças das Plantas/virologia , Tabaco/genética , Tabaco/virologia
15.
Sci Rep ; 9(1): 990, 2019 01 30.
Artigo em Inglês | MEDLINE | ID: mdl-30700772

RESUMO

Harpin proteins are produced by plant-pathogenic Gram-negative bacteria and regulate bacterial pathogenicity by inducing plant growth and defence responses in non-hosts. HpaG-Xcm, a novel harpin protein, was identified from Xanthomonas citri pv. mangiferaeindicae, which causes bacterial black spot of mango. Here, we describe the predicted structure and functions of HpaG-Xcm and investigate the mechanism of heat resistance. The HpaG-Xcm amino acid sequence contains seven motifs and two α-helices, in the N- and C-terminals, respectively. The N-terminal α-helical region contains two heptads, which form the coiled-coil (CC) structure. The CC region, which is on the surface of HpaG-Xcm, forms oligomeric aggregates by forming hydrophobic interactions between hydrophobic amino acids. Like other harpins, HpaG-Xcm was heat stable, promoted root growth and induced a hypersensitive response (HR) and systemic acquired resistance in non-host plants. Subjecting HpaG-Xcm to high temperatures altered the gene expression induced by HpaG-Xcm in tobacco leaves, probably due to changes in the spatial structure of HpaG-Xcm. Phenotypic tests revealed that the high-temperature treatments reduced the HR and disease resistance induced by HpaG-Xcm but had little effect on growth promotion. These findings indicate that the stability of interactions between CC and plants may be associated with thermal stability of HpaG-Xcm.


Assuntos
Proteínas de Bactérias/metabolismo , Resistência à Doença/genética , Regulação da Expressão Gênica de Plantas , Temperatura Alta , Xanthomonas/genética , Sequência de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Bactérias/isolamento & purificação , Filogenia , Doenças das Plantas/virologia , Folhas de Planta/genética , Folhas de Planta/virologia , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Tabaco/genética , Tabaco/imunologia , Tabaco/virologia , Vírus do Mosaico do Tabaco/fisiologia
16.
J Agric Food Chem ; 67(8): 2148-2156, 2019 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-30730738

RESUMO

Plant viral diseases seriously affect crop yield and quality. The natural product gramine (1) and its simple structural analogues 2-35 were synthesized from indoles, amines, and aldehydes in one step. The antiviral effects of these alkaloids were evaluated systematically. Most of these compounds were found to have higher antiviral effects than commercial ribavirin for the first time. Especially compounds 22, 30, and 31 exhibited significantly higher effects than ningnanmycin, thereby emerging as novel antiviral leads for further optimization. The preliminary implementation indicated that these compounds likely inhibit the assembly of tobacco mosaic virus (TMV) by cross-linking TMV capsid protein. Gramine analogues were also found to have broad-spectrum fungicidal effects. Although gramine has been reported to have influence on germination and development of Erysiphe graminis, these compounds displayed no fungicidal effects against Blumeria graminis f. sp. tritici on wheat in our test. Some of these compounds also exhibited certain insecticidal activities.


Assuntos
Antivirais/farmacologia , Produtos Biológicos/farmacologia , Alcaloides Indólicos/farmacologia , Antivirais/química , Produtos Biológicos/química , Descoberta de Drogas , Alcaloides Indólicos/química , Vírus de Plantas/efeitos dos fármacos , Vírus de Plantas/fisiologia , Relação Estrutura-Atividade , Vírus do Mosaico do Tabaco/efeitos dos fármacos , Vírus do Mosaico do Tabaco/fisiologia
18.
mBio ; 9(4)2018 07 10.
Artigo em Inglês | MEDLINE | ID: mdl-29991585

RESUMO

Plant viruses cross the barrier of the plant cell wall by moving through intercellular channels, termed plasmodesmata, to invade their hosts. They accomplish this by encoding movement proteins (MPs), which act to alter plasmodesmal gating. How MPs target to plasmodesmata is not well understood. Our recent characterization of the first plasmodesmal localization signal (PLS) identified in a viral MP, namely, the MP encoded by the Tobamovirus Tobacco mosaic virus (TMV), now provides the opportunity to identify host proteins that recognize this PLS and may be important for its plasmodesmal targeting. One such candidate protein is Arabidopsis synaptotagmin A (SYTA), which is required to form endoplasmic reticulum (ER)-plasma membrane contact sites and regulates the MP-mediated trafficking of begomoviruses, tobamoviruses, and potyviruses. In particular, SYTA interacts with, and regulates the cell-to-cell transport of, both TMV MP and the MP encoded by the Tobamovirus Turnip vein clearing virus (TVCV). Using in planta bimolecular fluorescence complementation (BiFC) and yeast two-hybrid assays, we show here that the TMV PLS interacted with SYTA. This PLS sequence was both necessary and sufficient for interaction with SYTA, and the plasmodesmal targeting activity of the TMV PLS was substantially reduced in an Arabidopsis syta knockdown line. Our findings show that SYTA is one host factor that can recognize the TMV PLS and suggest that this interaction may stabilize the association of TMV MP with plasmodesmata.IMPORTANCE Plant viruses use their movement proteins (MPs) to move through host intercellular connections, plasmodesmata. Perhaps one of the most intriguing, yet least studied, aspects of this transport is the MP signal sequences and their host recognition factors. Recently, we have described the plasmodesmal localization signal (PLS) of the Tobacco mosaic virus (TMV) MP. Here, we identified the Arabidopsis synaptotagmin A (SYTA) as a host factor that recognizes TMV MP PLS and promotes its association with the plasmodesmal membrane. The significance of these findings is two-fold: (i) we identified the TMV MP association with the cell membrane at plasmodesmata as an important PLS-dependent step in plasmodesmal targeting, and (ii) we identified the plant SYTA protein that specifically recognizes PLS as a host factor involved in this step.


Assuntos
Proteínas de Arabidopsis/metabolismo , Interações Hospedeiro-Patógeno , Proteínas do Movimento Viral em Plantas/metabolismo , Plasmodesmos/metabolismo , Plasmodesmos/virologia , Sinaptotagminas/metabolismo , Vírus do Mosaico do Tabaco/fisiologia , Arabidopsis , Ligação Proteica , Transporte Proteico
19.
Hist Philos Life Sci ; 40(3): 41, 2018 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-30003445

RESUMO

This paper considers the foundational role of the contagium vivum fluidum-first proposed by the Dutch microbiologist Martinus Beijerinck in 1898-in the history of virology, particularly in shaping the modern virus concept, defined in the 1950s. Investigating the cause of mosaic disease of tobacco, previously shown to be an invisible and filterable entity, Beijerinck concluded that it was neither particulate like the bacteria implicated in certain infectious diseases, nor soluble like the toxins and enzymes responsible for symptoms in others. He offered a completely new explanation, proposing that the agent was a "living infectious fluid" whose reproduction was intimately linked to that of its host cell. Difficult to test at the time, the contagium vivum fluidum languished in obscurity for more than three decades. Subsequent advances in technologies prompted virus researchers of the 1930s and 1940s-the first to separate themselves from bacteriologists-to revive the idea. They found in it both the seeds for their emerging virus concept and a way to bring hitherto opposing thought styles about the nature of viruses and life together in consensus. Thus, they resurrected Beijerinck as the founding father, and contagium vivum fluidum as the core concept of their discipline.


Assuntos
Doenças das Plantas/história , Vírus do Mosaico do Tabaco/fisiologia , Vírus do Mosaico do Tabaco/patogenicidade , Tabaco/virologia , Virologia/história , História do Século XIX , História do Século XX , Doenças das Plantas/virologia
20.
Arch Virol ; 163(10): 2835-2840, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29948382

RESUMO

Low-temperature atmospheric-pressure air plasma is a source of charged and neutral gas species. In this study, N-carrying tobacco plants were inoculated with plasma irradiated and non-irradiated tobacco mosaic virus (TMV) solution, resulting in necrotic local lesions on non-irradiated, but not on irradiated, TMV-inoculated leaves. Virus particles were disrupted by plasma irradiation in an exposure-dependent manner, but the viral coat protein subunit was not. TMV RNA was also fragmented in a time-dependent manner. These results indicate that plasma irradiation of TMV can collapse viral particles to the subunit level, degrading TMV RNA and thereby leading to a loss of infectivity.


Assuntos
Doenças das Plantas/virologia , Gases em Plasma/química , Gases em Plasma/farmacologia , Vírus do Mosaico do Tabaco/efeitos dos fármacos , Vírus do Mosaico do Tabaco/fisiologia , Tabaco/virologia , Replicação Viral/efeitos dos fármacos
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