Management of Plant Viruses through Host RNAi Defense Mechanism

2021 ◽  
pp. 181-196
Author(s):  
Nandlal Choudhary
Keyword(s):  
Defense Mechanism ◽  
Plant Viruses

scholarly journals Role of RNA Silencing Suppression in the Pathogenicity and Host Specificity of the Grapevine Virus A

2010 ◽  
Author(s):  
Munir Mawassi ◽  
Valerian Dolja
Keyword(s):  
Rna Silencing ◽  
Defense Mechanism ◽  
Plant Viruses ◽  
Small Interfering Rnas ◽  
Grapevine Virus ◽  
Virus Transport ◽  
Systematic Analysis ◽  
Grapevine Virus A ◽  
Silencing Suppression ◽  
And Function

RNA silencing is a defense mechanism that functions against virus infection and involves sequence-specific degradation of viral RNA. Diverse RNA and DNA viruses of plants encode RNA silencing suppressors (RSSs), which, in addition to their role in viral counterdefense, were implicated in the efficient accumulation of viral RNAs, virus transport, pathogenesis, and determination of the virus host range. Despite rapidly growing understanding of the mechanisms of RNA silencing suppression, systematic analysis of the roles played by diverse RSSs in virus biology and pathology is yet to be completed. Our research was aimed at conducting such analysis for two grapevine viruses, Grapevine virus A (GVA) and Grapevine leafroll-associated virus-2 (GLRaV- 2). Our major achievements on the previous cycle of BARD funding are as follows. 1. GVA and GLRaV-2 were engineered into efficient gene expression and silencing vectors for grapevine. The efficient techniques for grapevine infection resulting in systemic expression or silencing of the recombinant genes were developed. Therefore, GVA and GLRaV-2 were rendered into powerful tools of grapevine virology and functional genomics. 2. The GVA and GLRaV-2 RSSs, p10 and p24, respectively, were identified, and their roles in viral pathogenesis were determined. In particular, we found that p10 functions in suppression and pathogenesis are genetically separable. 3. We revealed that p10 is a self-interactive protein that is targeted to the nucleus. In contrast, p24 mechanism involves binding small interfering RNAs in the cytoplasm. We have also demonstrated that p10 is relatively weak, whereas p24 is extremely strong enhancer of the viral agroinfection. 4. We found that, in addition to the dedicated RSSs, GVA and GLRaV-2 counterdefenses involve ORF1 product and leader proteases, respectively. 5. We have teamed up with Dr. Koonin and Dr. Falnes groups to study the evolution and function of the AlkB domain presents in GVA and many other plant viruses. It was demonstrated that viral AlkBs are RNA-specific demethylases thus providing critical support for the biological relevance of the novel process of AlkB-mediated RNA repair. 

Autophagy in Plant-Virus Interactions

2020 ◽  
Vol 7 (1) ◽  
pp. 403-419 ◽  
Author(s):  
Meng Yang ◽  
Asigul Ismayil ◽  
Yule Liu
Keyword(s):  
Plant Virus ◽  
Defense Mechanism ◽  
Degradation Pathway ◽  
Plant Viruses ◽  
Antiviral Defense ◽  
Autophagy Pathway ◽  
Virus Interactions ◽  
Plant Pathogen Interactions ◽  
Cellular Components

Autophagy is a conserved vacuole/lysosome-mediated degradation pathway for clearing and recycling cellular components including cytosol, macromolecules, and dysfunctional organelles. In recent years, autophagy has emerged to play important roles in plant-pathogen interactions. It acts as an antiviral defense mechanism in plants. Moreover, increasing evidence shows that plant viruses can manipulate, hijack, or even exploit the autophagy pathway to promote pathogenesis, demonstrating the pivotal role of autophagy in the evolutionary arms race between hosts and viruses. In this review, we discuss recent findings about the antiviral and proviral roles of autophagy in plant-virus interactions.

scholarly journals Olive Mild Mosaic Virus Coat Protein and P6 Are Suppressors of RNA Silencing, and Their Silencing Confers Resistance against OMMV

Viruses ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 416 ◽  
Author(s):  
Carla Varanda ◽  
Patrick Materatski ◽  
Maria Campos ◽  
Maria Clara ◽  
Gustavo Nolasco ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Rna Silencing ◽  
Defense Mechanism ◽  
Plant Viruses ◽  
Open Reading Frames ◽  
Mild Mosaic ◽  
Suppressor Activity ◽  
Mild Mosaic Virus ◽  
Virus Coat ◽  
Viral Suppressors

RNA silencing is an important defense mechanism in plants, yet several plant viruses encode proteins that suppress this mechanism. In this study, the genome of the Olive mild mosaic virus (OMMV) was screened for silencing suppressors. The full OMMV cDNA and 5 OMMV open reading frames (ORFs) were cloned into the Gateway binary vector pK7WG2, transformed into Agrobacterium tumefaciens, and agroinfiltrated into N. benthamiana 16C plants. CP and p6 showed suppressor activity, with CP showing significantly higher activity than p6, yet activity that was lower than the full OMMV, suggesting a complementary action of CP and p6. These viral suppressors were then used to induce OMMV resistance in plants based on RNA silencing. Two hairpin constructs targeting each suppressor were agroinfiltrated in N. benthamiana plants, which were then inoculated with OMMV RNA. When silencing of both suppressors was achieved, a significant reduction in viral accumulation and symptom attenuation was observed as compared to those of the controls, as well as to when each construct was used alone, proving them to be effective against OMMV infection. This is the first time that a silencing suppressor was found in a necrovirus, and that two independent proteins act as silencing suppressors in a virus member of the Tombusviridae family.

scholarly journals Tobacco Rattle Virus 16-Kilodalton Protein Encodes a Suppressor of RNA Silencing That Allows Transient Viral Entry in Meristems

2008 ◽  
Vol 82 (8) ◽  
pp. 4064-4071 ◽  
Author(s):  
Ana M. Martín-Hernández ◽  
David C. Baulcombe
Keyword(s):  
Viral Entry ◽  
Rna Silencing ◽  
Defense Mechanism ◽  
Rna Virus ◽  
Secondary Infection ◽  
Infected Plant ◽  
Tobacco Rattle Virus ◽  
Plant Viruses ◽  
Wild Type Virus ◽  
Positive Strand Rna

ABSTRACT RNA silencing is a host defense mechanism that limits the accumulation and spread of viruses in infected plants. Correspondingly, plant viruses encode suppressors of silencing. In the positive-strand RNA virus Tobacco rattle virus (TRV), the suppressor of silencing is a 16-kDa (16K) protein encoded by RNA1. The suppressor action of the 16K protein is transient and weaker than that of the P19 suppressor, encoded by tomato bushy stunt virus. Mutant TRV that does not produce its suppressor, unlike other suppressor-defective viruses, is competent to accumulate and spread systemically in the infected plant. However, this mutant virus does not exhibit the transient invasion of the meristem that is characteristic of the wild-type virus. Based on this analysis, we propose that the 16K suppressor of silencing allows TRV to transiently invade the meristem. Our data are consistent with a mechanism of long-term meristem virus exclusion that is dependent on a transient invasion of the meristem early in the infection cycle. This novel mechanism of meristem exclusion may be associated with the phenomenon of recovery in virus-infected plants in which upper leaves have little or no virus and are immune to secondary infection by the same virus.

Ectodesmata as Revealed By Freeze-Etch Preparations of Plant Epidermal Cell Walls

1973 ◽  
Vol 31 ◽  
pp. 468-469
Author(s):  
N.C. Lyon ◽  
W. C. Mueller
Keyword(s):  
Electron Microscopy ◽  
Acetic Acid ◽  
Nitric Acid ◽  
Oxalic Acid ◽  
Light Microscopy ◽  
Epidermal Cell ◽  
Cell Walls ◽  
Plant Viruses ◽  
Plant Leaves ◽  
Thin Sections

Schumacher and Halbsguth first demonstrated ectodesmata as pores or channels in the epidermal cell walls in haustoria of Cuscuta odorata L. by light microscopy in tissues fixed in a sublimate fixative (30% ethyl alcohol, 30 ml:glacial acetic acid, 10 ml: 65% nitric acid, 1 ml: 40% formaldehyde, 5 ml: oxalic acid, 2 g: mecuric chloride to saturation 2-3 g). Other workers have published electron micrographs of structures transversing the outer epidermal cell in thin sections of plant leaves that have been interpreted as ectodesmata. Such structures are evident following treatment with Hg++ or Ag+ salts and are only rarely observed by electron microscopy. If ectodesmata exist without such treatment, and are not artefacts, they would afford natural pathways of entry for applied foliar solutions and plant viruses.

Solid-phase immunoelectron microscopy for rapid diagnosis of enteroviruses

1984 ◽  
Vol 42 ◽  
pp. 226-227 ◽  
Author(s):  
K. Pegg-Feige ◽  
F. W. Doane
Keyword(s):  
Electron Microscopy ◽  
Cell Culture ◽  
Immunoelectron Microscopy ◽  
Detection Method ◽  
Solid Phase ◽  
Protein A ◽  
Plant Viruses ◽  
Rapid Diagnosis ◽  
Virus Diagnosis ◽  
Antiviral Antibody

Immunoelectron microscopy (IEM) applied to rapid virus diagnosis offers a more sensitive detection method than direct electron microscopy (DEM), and can also be used to serotype viruses. One of several IEM techniques is that introduced by Derrick in 1972, in which antiviral antibody is attached to the support film of an EM specimen grid. Originally developed for plant viruses, it has recently been applied to several animal viruses, especially rotaviruses. We have investigated the use of this solid phase IEM technique (SPIEM) in detecting and identifying enteroviruses (in the form of crude cell culture isolates), and have compared it with a modified “SPIEM-SPA” method in which grids are coated with protein A from Staphylococcus aureus prior to exposure to antiserum.

A Sensitive On-Grid Immunoelectron Microscopic Procedure for Diagnosis of Rotavirus Infection

1980 ◽  
Vol 38 ◽  
pp. 506-507
Author(s):  
M. F. Miller ◽  
A. R. Rubenstein
Keyword(s):  
Electron Microscopy ◽  
Specific Antibody ◽  
Immune Complexes ◽  
Acute Gastroenteritis ◽  
Plant Viruses ◽  
Aggregation Process ◽  
Microscopic Technique ◽  
Fecal Material ◽  
Present Communication ◽  
Number Of Particles

Studies of rotavirus particles in humans, monkeys and various non-primates with acute gastroenteritis have involved detection of virus in fecal material by electron microscopy. The EM techniques most commonly employed have been the conventional negative staining (Fig. 1) and immune aggregation (Fig. 2) procedures. Both methods are somewhat insensitive and can most reliably be applied to samples containing large quantities of virus either naturaLly or as a result of concentration by ultracentrifugation. The formation of immune complexes by specific antibody in the immune aggregation procedures confirms the rotavirus diagnosis, but the number of particles per given microscope field is effectively reduced by the aggregation process. In the present communication, we describe use of an on-grid immunoelectron microscopic technique in which rotavirus particles are mounted onto microscope grids that were pre-coated with specific antibody. The technique is a modification of a method originalLy introduced by Derrick (1) for studies of plant viruses.

The Use of the Defense Mechanism Test to Aid in Understanding the Personality of Senior Executives and the Implications for Their Careers

2009 ◽  
Vol 30 (1) ◽  
pp. 73-96 ◽  
Author(s):  
Olya Khaleelee
Keyword(s):  
Crisis Intervention ◽  
Defense Mechanisms ◽  
Defense Mechanism ◽  
Senior Executives ◽  
Ideal Types ◽  
The Individual ◽  
Test Profiles ◽  
Real Test

This paper describes the use of the Defense Mechanism Test as an aid in helping to assess senior executives in four areas: for selection, development, career strategy, and crisis intervention. The origins of this test, developed to measure the defense mechanisms used to protect the individual from stress, are described. The paper shows how it was used to predict the capacity of trainee fighter pilots to withstand stress and its later application to other stressful occupations. Finally, some ideal types of the test are shown followed by four real test profiles, two of them with their associated histories.

Iron status in diabetes mellitus

2019 ◽  
pp. 7-12
Keyword(s):  
Diabetes Mellitus ◽  
Beta Cells ◽  
Defense Mechanism ◽  
Acute Stress ◽  
Islet Cells ◽  
Iron Status ◽  
Acute Phase Reactant ◽  
Iron Deposition ◽  
Muscle Tissues ◽  
High Production

Diabetes mellitus can be defined as chronic metabolic disease which results from either relative or complete absence of insulin by the pancreatic beta islet cells. This in-turn may lead to hyperglycemia due to disturbances in the metabolism of glucose. In the human body, iron is con- sidered to be an effective pro-oxidant and participates in the generation of reactive oxygen species (ROS) such as hydroxyl radical. Because of the poor antioxidant defense mechanism of beta cells (low production of antioxidant enzymes such as catalase, glutathione peroxidase and dismutase), so they are highly prone to iron-induced oxidative stress and iron deposition in it and this will lead to apoptosis, and subsequently insulin deficiency. This iron deposition in beta cells will also lead to insulin resistance by reducing insulin extracting ability of the liver and inhibiting glucose uptake in muscle tissues and fats, this in turn will result in high production of hepatic glucose. Ferritin which is an acute phase reactant protein, that responds to acute stress like trauma, infections, tissue necrosis and surgery, it can produce diabetes mellitus either through inflammation or by increasing iron stores.

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