The document discusses plant disease resistance genes (R-genes) and their importance in crop breeding for disease resistance. It contains the following key points:
1. R-genes encode receptors that recognize pathogen effector proteins and trigger plant immune responses. Most R-genes contain nucleotide binding and leucine-rich repeat domains.
2. Dozens of R-genes have been cloned from various plants using map-based cloning, transposon tagging, or a new method called MutRenSeq that enriches for R-gene sequences.
3. Introducing R-genes from wild crop relatives into domestic crops can provide natural and sustainable resistance to diseases while avoiding pesticide use and potential environmental damage.
An entomopathogenic fungus seminar was presented covering the role of these fungi in insect control. The key points are:
Entomopathogenic fungi such as Beauveria, Metarhizium, Lecanicillium, and Nomurae act as parasites to insects, killing or disabling them. They are effective against many agricultural and forest pests like beetles, caterpillars, whiteflies, and grasshoppers. These fungi penetrate the insect cuticle, grow internally, and produce toxins that ultimately kill the host. They have potential for use in reducing chemical pesticide use in agriculture.
The document discusses systemic acquired resistance (SAR), which confers long-lasting protection against a broad spectrum of pathogens. SAR is induced by initial infection and involves the signaling molecule salicylic acid, leading to accumulation of pathogenesis-related proteins throughout the plant. Key regulators of SAR include NPR1, which is required for SAR, and salicylic acid, which is involved in transmitting the defense signal systemically.
This document discusses genes in plants that provide disease resistance. It begins by outlining the plant immune system and the zig-zag model involving PAMP-triggered immunity and effector-triggered immunity. It then describes different classes of plant resistance genes based on their structural features and domains. The document also discusses the functions of resistance genes in signaling plant defenses, and provides examples of resistance genes that have been cloned and provide resistance against various pathogens like fungi, viruses, nematodes, and more.
This document summarizes induced plant resistance against pathogens. It discusses the historical background of induced resistance being first observed over 100 years ago. It describes different types of induced resistance including systemic acquired resistance (SAR) and induced systemic resistance (ISR). SAR is mediated by salicylic acid and involves pathogenesis-related proteins, while ISR is mediated by jasmonic acid and ethylene. Biological agents like PGPR bacteria and plant extracts can also induce resistance. Signal transduction pathways underlying these responses are triggered upon pathogen recognition. While induced resistance offers opportunities for crop protection, practical applications are currently limited to some plants.
This document discusses types of plant disease epidemics. It defines an epidemic as a disease occurring year after year at a moderate to severe level or an increase in disease within a population. Epidemiology is the study of disease in populations. The main types of epidemics discussed are monocyclic, polycyclic, and polyetic. Monocyclic diseases have one infection cycle per season, while polycyclic diseases can have multiple cycles from secondary infections. Polyetic diseases take multiple years to produce inoculum and may not cause new infections every year. Examples of each type are provided.
This document discusses entomopathogenic viruses and their potential use for controlling insect pests. It provides background on virus structure and describes several types of viruses that infect insects, including baculoviruses. The document then discusses how genetic engineering can be used to modify viruses to optimize their speed of kill or increase virulence. Specific examples are given of genes inserted or deleted from baculoviruses to improve pest control. The conclusion emphasizes how genetic engineering combined with virus production technology may enable more effective and economical viral pesticides.
Gene for-gene hypothesis & its validty in the present scenarioDr. Nimit Kumar
This document summarizes a seminar on disease development and resistance. It discusses the disease triangle, types of resistance, components of disease resistance including R and Avr genes, and Flor's gene-for-gene hypothesis. Molecular models of direct and indirect R-Avr gene interaction are presented. Examples of characterized R genes in crops like maize, rice, and tobacco are provided. Past work on disease resistance in flax at the university is summarized, as is current molecular characterization work in the department.
The document discusses plant disease resistance genes (R-genes) and their importance in crop breeding for disease resistance. It contains the following key points:
1. R-genes encode receptors that recognize pathogen effector proteins and trigger plant immune responses. Most R-genes contain nucleotide binding and leucine-rich repeat domains.
2. Dozens of R-genes have been cloned from various plants using map-based cloning, transposon tagging, or a new method called MutRenSeq that enriches for R-gene sequences.
3. Introducing R-genes from wild crop relatives into domestic crops can provide natural and sustainable resistance to diseases while avoiding pesticide use and potential environmental damage.
An entomopathogenic fungus seminar was presented covering the role of these fungi in insect control. The key points are:
Entomopathogenic fungi such as Beauveria, Metarhizium, Lecanicillium, and Nomurae act as parasites to insects, killing or disabling them. They are effective against many agricultural and forest pests like beetles, caterpillars, whiteflies, and grasshoppers. These fungi penetrate the insect cuticle, grow internally, and produce toxins that ultimately kill the host. They have potential for use in reducing chemical pesticide use in agriculture.
The document discusses systemic acquired resistance (SAR), which confers long-lasting protection against a broad spectrum of pathogens. SAR is induced by initial infection and involves the signaling molecule salicylic acid, leading to accumulation of pathogenesis-related proteins throughout the plant. Key regulators of SAR include NPR1, which is required for SAR, and salicylic acid, which is involved in transmitting the defense signal systemically.
This document discusses genes in plants that provide disease resistance. It begins by outlining the plant immune system and the zig-zag model involving PAMP-triggered immunity and effector-triggered immunity. It then describes different classes of plant resistance genes based on their structural features and domains. The document also discusses the functions of resistance genes in signaling plant defenses, and provides examples of resistance genes that have been cloned and provide resistance against various pathogens like fungi, viruses, nematodes, and more.
This document summarizes induced plant resistance against pathogens. It discusses the historical background of induced resistance being first observed over 100 years ago. It describes different types of induced resistance including systemic acquired resistance (SAR) and induced systemic resistance (ISR). SAR is mediated by salicylic acid and involves pathogenesis-related proteins, while ISR is mediated by jasmonic acid and ethylene. Biological agents like PGPR bacteria and plant extracts can also induce resistance. Signal transduction pathways underlying these responses are triggered upon pathogen recognition. While induced resistance offers opportunities for crop protection, practical applications are currently limited to some plants.
This document discusses types of plant disease epidemics. It defines an epidemic as a disease occurring year after year at a moderate to severe level or an increase in disease within a population. Epidemiology is the study of disease in populations. The main types of epidemics discussed are monocyclic, polycyclic, and polyetic. Monocyclic diseases have one infection cycle per season, while polycyclic diseases can have multiple cycles from secondary infections. Polyetic diseases take multiple years to produce inoculum and may not cause new infections every year. Examples of each type are provided.
This document discusses entomopathogenic viruses and their potential use for controlling insect pests. It provides background on virus structure and describes several types of viruses that infect insects, including baculoviruses. The document then discusses how genetic engineering can be used to modify viruses to optimize their speed of kill or increase virulence. Specific examples are given of genes inserted or deleted from baculoviruses to improve pest control. The conclusion emphasizes how genetic engineering combined with virus production technology may enable more effective and economical viral pesticides.
Gene for-gene hypothesis & its validty in the present scenarioDr. Nimit Kumar
This document summarizes a seminar on disease development and resistance. It discusses the disease triangle, types of resistance, components of disease resistance including R and Avr genes, and Flor's gene-for-gene hypothesis. Molecular models of direct and indirect R-Avr gene interaction are presented. Examples of characterized R genes in crops like maize, rice, and tobacco are provided. Past work on disease resistance in flax at the university is summarized, as is current molecular characterization work in the department.
This document summarizes research on symbiont-mediated protection in insect hosts. It discusses how endosymbionts can protect insects from microbial diseases, parasites, predators, antiherbivorous plant compounds, and insecticides through direct and host-mediated mechanisms. Examples are provided of endosymbionts protecting aphids, whiteflies, mosquitoes, flies, honeybees, termites, weevils and other insects. Some endosymbionts produce toxins or degrade compounds like fungicides, plant alkaloids and insecticides. Future applications include using symbionts to develop new biopesticides or combine antibiotics with pesticides to overcome resistance.
Chemical composition and physical properties of plant virusesN.H. Shankar Reddy
This document discusses the chemical composition and physical properties of plant viruses. It notes that plant viruses contain nucleic acids (RNA or DNA) and protein coats. The nucleic acid content ranges from 5-40% and determines infectivity, while the protein coat protects the nucleic acid and facilitates entry into host cells. It also discusses various physical properties of viruses like their thermal inactivation temperature, dilution endpoint, longevity in crude sap extractions, and use of local lesion assays to quantify infectivity.
Activation of natural host defence by elicitors for management of post harves...Vinod Upadhyay
India suffers post-harvest losses of over $2 billion annually due to spoilage of 30% of fruits and vegetables after harvesting. Elicitors are compounds that can activate natural host defense responses in plants. Some examples of elicitors that have been shown to reduce post-harvest diseases include salicylic acid, methyl jasmonate, harpin, and oligandrin. Elicitors work by priming the plant's defenses through mechanisms like reactive oxygen species production, phytoalexin production, and hypersensitive response. The effectiveness of elicitors can depend on factors like cultivar genotype, environmental conditions, and whether they are combined with other treatments like fungicides or biocontrol agents.
Systemic acquired resistance (SAR) is a whole-plant immune response that is activated upon localized infection by a pathogen. It provides long-lasting, broad-spectrum resistance against secondary infections. SAR involves the production of mobile signaling molecules like methyl salicylate, azelaic acid, and glycerol-3-phosphate in infected tissues that activate defenses in distant, uninfected tissues. This results in increased expression of pathogenesis-related proteins and other defenses. The NPR1 protein is a master regulator of the SAR response.
Resistance mechanism In Plants - R GENE SunandaArya
This document summarizes plant disease resistance mechanisms. It discusses R-genes, which confer resistance to pathogens by encoding proteins that recognize pathogen avirulence genes. The main classes of R-genes contain nucleotide binding and leucine rich repeat domains. Resistance occurs through gene-for-gene interactions between plant R-genes and pathogen avirulence genes. Additional resistance mechanisms discussed include the guard hypothesis where R-proteins interact with host proteins guarded from pathogen effectors, and pathogen associated molecular pattern recognition. The document outlines the structure, classes, and mechanisms of action of R-genes in plant pathogen interactions.
This document provides information on several entomopathogenic fungi used for microbial control of insect pests. It discusses the fungi Beauveria bassiana, Metarhizium anisopliae, Verticillium lecanii, Paecilomyces fumosoroseus, and Hirsutella thomsoni. For each fungus, it describes the target pests, mass production methods, and field application procedures. The document emphasizes that these entomopathogenic fungi are effective alternatives to chemical pesticides for controlling agricultural insect pests while causing less damage to the environment.
- Insects have evolved symbiotic relationships with bacteria and other microorganisms over 250 million years. These endosymbionts can be found inside insects' cells, between cells, and in their guts.
- Endosymbionts play important roles in insect nutrition, defense, reproduction, and environmental adaptation. For example, Buchnera provides essential amino acids to aphids.
- Wolbachia is one of the most common endosymbionts and can manipulate insect reproduction through mechanisms like cytoplasmic incompatibility, parthenogenesis, feminization, and male-killing. Studying endosymbionts enhances understanding of evolution, disease control, and biocontrol applications
This document provides information about microbial biopesticides, specifically entomopathogenic bacteria, viruses, and fungi. It begins with an introduction to microbial control and defines entomopathogens. It then discusses the history, classification, mode of action, symptoms, and target pests of entomopathogenic bacteria including Bacillus thuringiensis. Next, it covers entomopathogenic viruses including classification, examples, and mode of action. Finally, it summarizes entomopathogenic fungi including some of the most common types, their history of use, mode of action, and toxins produced.
SEROLOGICAL METHODS FOR DETECTION OF PLANT PATHOGENSHARISH J
This document discusses serological methods for detecting plant pathogens. It explains that serodiagnosis involves inducing an immune response in an animal to produce antibodies against a pathogen's antigens. These antibodies can then be used to detect the presence of the pathogen. The document describes several serological testing methods including ring interface tests, microprecipitin tests, double diffusion tests, ELISA, immunosorbent electron microscopy, and immunofluorescent staining. It concludes that serodiagnosis is a sensitive tool for identifying pathogens, detecting infections, and quantifying crop diseases.
Gene for gene system in plant fungus interactionVinod Upadhyay
1. Plant-fungus interactions can be characterized by gene-for-gene systems where a plant resistance gene corresponds to a fungal avirulence gene. Vertical or race-specific resistance follows this pattern and is not durable due to high selection pressure.
2. R proteins in plants recognize specific pathogen effectors or avirulence proteins through direct or indirect models. Direct models involve recognition of effectors by R protein receptors. Indirect models involve the effector targeting or modifying a host protein that is then recognized by the R protein.
3. Understanding gene-for-gene systems and how plants recognize pathogens at the molecular level can enable new strategies for disease control through deployment of resistance genes and exploitation of avirulence
Plant immunity towards an integrated view of plant pathogen interaction and i...Pavan R
This document discusses plant immunity and pathogen interactions. It provides an overview of the different forms of plant resistance including antipathy, hindrance, and defense. It describes the phases of plant immunity including PAMP-triggered immunity, effector-triggered susceptibility, and effector-triggered immunity. It also discusses various defense responses in plants against pathogens such as stomatal closure, ion fluxes, oxidative burst, role of phytohormones, hypersensitive response, and systemic acquired resistance. Finally, it summarizes some breeding and biotechnological strategies used to induce resistance in plants like manipulating PAMP receptors, gene pyramiding, use of resistance genes and antifungal fusion proteins, and utilization of phytoalexins.
1. The document discusses the morphology, replication, assembly and architecture of plant virus genomes. It describes the different shapes that plant virus particles can take including rod-shaped, isometric and geminivirus particles.
2. The tobacco mosaic virus (TMV) genome is discussed in detail. The TMV particle is a rigid helical rod consisting of RNA and coat proteins. The coat proteins assemble around the RNA to form the distinctive shape.
3. Assembly of the TMV virus involves initial interactions between coat proteins and RNA near the origin of assembly site, followed by rapid extension in the 5' direction and slower extension in the 3' direction through addition of protein subunits and disks.
Role of microbial toxins in plant pathogenesisansarishahid786
This document discusses the role of microbial toxins in plant pathogenesis. It defines toxins as metabolites excreted or released by pathogens that damage host cells. Toxins are classified based on their source and specificity. Host-specific toxins only affect a pathogen's host, while non-host specific toxins can damage unrelated plants. Toxins disrupt cell permeability, metabolic processes, and growth regulation, injuring and killing host cells. They play an important role in disease development and symptom expression.
This document discusses terminology related to virus transmission by vectors and different types of virus-vector relationships.
1. It defines terms like acquisition access period, acquisition feeding period, inoculation access period, inoculation feeding period, and transmission threshold that describe the process of a vector acquiring and transmitting a virus.
2. It describes three main types of virus-vector relationships: non-persistent, semi-persistent, and persistent. Non-persistent viruses are stylet-borne and lost quickly. Semi-persistent viruses persist for 10-100 hours in the foregut. Persistent viruses circulate and may multiply in the vector.
3. Within persistent viruses, it further distinguishes circulative non-propagative
The document provides an overview of different types of entomopathogenic microbes (viruses, bacteria, fungi, nematodes, protozoa) used for insect management. It discusses the history, mode of action, symptoms caused, and examples of specific microbes used to control various insect pests for different crops. These include Bacillus thuringiensis for lepidopteran larvae, Beauveria bassiana for sucking pests, Metarhizium anisopliae for beet armyworm and rhinoceros beetle, Steinernema carpocapsea for soil-dwelling insects, and Nosema locustae for grasshoppers. The advantages of using entomopathogenic
This document summarizes systemic acquired resistance (SAR) in plants. It discusses that SAR is a defense response activated by pathogens that results in long-lasting, broad-spectrum resistance in distant parts of the plant. The key points are:
- SAR involves accumulation of salicylic acid and pathogenesis-related proteins in distant, uninfected tissues which provides resistance against a wide range of pathogens.
- It is activated after an initial infection causes cell death and necrosis, and involves mobile signaling molecules like methyl salicylate that transmit the defense signal systemically.
- SAR protects against future infections by viruses, fungi, bacteria and activates genes that encode antimicrobial pathogenesis-related proteins.
Pathogenesis-related (PR) proteins are a diverse group of plant proteins that are produced in greater amounts when plants are infected by pathogens or exposed to stress. There are at least 14 families of PR proteins that differ in their functions, properties, and modes of action. Some key PR proteins include PR1, PR2, and PR3. PR1 proteins have antifungal properties and may disrupt fungal membranes. PR2 are β-1,3-glucanases that degrade fungal cell walls. PR3 are chitinases that break down chitin in fungal cell walls, weakening the walls and killing fungi.
Plant microbe interaction by dr. ashwin chekeAshwin Cheke
PLANT MICROBE – INTERACTIONS AND THEIR MUTUAL BENEFITS IN ENHANCING SOIL HEALTH AND AGRICULTURAL PRODUCTION ,
IT ALSO INCREASE CROP PRODUCTIVITY AND IMPROVE SOIL HEALTH
This document discusses induced systemic resistance (ISR) in plants. It provides historical context on studies of induced resistance dating back to the late 1800s. ISR is defined as a phenomenon where treatment with certain chemicals or pathogens activates a plant's defenses throughout the plant. Key findings include:
- ISR is activated by rhizobacteria and involves jasmonic acid and ethylene signaling rather than salicylic acid signaling as in systemic acquired resistance.
- Several bacteria, fungi, chemicals, and elicitors are reported to induce ISR through different signaling pathways and defense responses.
- Further research is needed to fully understand ISR signaling and apply it effectively in fields to control plant diseases.
Rohit Jadhav presented on microbe-plant interactions. Key points include:
- Cyanobacteria and rhizobia have symbiotic relationships with plants, fixing nitrogen.
- Microbes in the rhizosphere and rhizoplane interact with plant roots, satisfying nutritional needs for both.
- Rhizosphere microbes can positively impact plants by nutrient solubilization or negatively through immobilization.
- Legumes form root nodules with rhizobia like Rhizobium spp. and Bradyrhizobium spp. to fix atmospheric nitrogen.
- Some non-legumes interact with nitrogen-fixing cyanobacteria and Frankia bacteria inside root nodules.
-
This document discusses techniques for engineering bacteriophages (phages) to enhance their potential as antimicrobial agents. It describes various methods for genetically modifying phage genomes, including homologous recombination, recombineering, and rebuilding genomes in vitro or in yeast. Synthetic phages have been engineered with broader host ranges or the ability to deliver genes conferring antibiotic sensitivity. Phage lysins have also been developed as antimicrobials targeting pathogens like MRSA. Overall, the document outlines how phage engineering is an area of active research with applications for treating antibiotic-resistant bacteria.
Bacterial pathogens of plants have specialized properties that allow them to infect plants. They parasitize plant cells and cause cell death. Important virulence factors include toxins, extracellular polysaccharides, and degradative enzymes. Bacterial pathogens use type III secretion systems and effector proteins to manipulate plant cells and cause disease symptoms. The interaction between bacterial effectors and plant resistance proteins determines if the interaction is compatible and leads to disease, or incompatible and triggers a hypersensitive response.
This document summarizes research on symbiont-mediated protection in insect hosts. It discusses how endosymbionts can protect insects from microbial diseases, parasites, predators, antiherbivorous plant compounds, and insecticides through direct and host-mediated mechanisms. Examples are provided of endosymbionts protecting aphids, whiteflies, mosquitoes, flies, honeybees, termites, weevils and other insects. Some endosymbionts produce toxins or degrade compounds like fungicides, plant alkaloids and insecticides. Future applications include using symbionts to develop new biopesticides or combine antibiotics with pesticides to overcome resistance.
Chemical composition and physical properties of plant virusesN.H. Shankar Reddy
This document discusses the chemical composition and physical properties of plant viruses. It notes that plant viruses contain nucleic acids (RNA or DNA) and protein coats. The nucleic acid content ranges from 5-40% and determines infectivity, while the protein coat protects the nucleic acid and facilitates entry into host cells. It also discusses various physical properties of viruses like their thermal inactivation temperature, dilution endpoint, longevity in crude sap extractions, and use of local lesion assays to quantify infectivity.
Activation of natural host defence by elicitors for management of post harves...Vinod Upadhyay
India suffers post-harvest losses of over $2 billion annually due to spoilage of 30% of fruits and vegetables after harvesting. Elicitors are compounds that can activate natural host defense responses in plants. Some examples of elicitors that have been shown to reduce post-harvest diseases include salicylic acid, methyl jasmonate, harpin, and oligandrin. Elicitors work by priming the plant's defenses through mechanisms like reactive oxygen species production, phytoalexin production, and hypersensitive response. The effectiveness of elicitors can depend on factors like cultivar genotype, environmental conditions, and whether they are combined with other treatments like fungicides or biocontrol agents.
Systemic acquired resistance (SAR) is a whole-plant immune response that is activated upon localized infection by a pathogen. It provides long-lasting, broad-spectrum resistance against secondary infections. SAR involves the production of mobile signaling molecules like methyl salicylate, azelaic acid, and glycerol-3-phosphate in infected tissues that activate defenses in distant, uninfected tissues. This results in increased expression of pathogenesis-related proteins and other defenses. The NPR1 protein is a master regulator of the SAR response.
Resistance mechanism In Plants - R GENE SunandaArya
This document summarizes plant disease resistance mechanisms. It discusses R-genes, which confer resistance to pathogens by encoding proteins that recognize pathogen avirulence genes. The main classes of R-genes contain nucleotide binding and leucine rich repeat domains. Resistance occurs through gene-for-gene interactions between plant R-genes and pathogen avirulence genes. Additional resistance mechanisms discussed include the guard hypothesis where R-proteins interact with host proteins guarded from pathogen effectors, and pathogen associated molecular pattern recognition. The document outlines the structure, classes, and mechanisms of action of R-genes in plant pathogen interactions.
This document provides information on several entomopathogenic fungi used for microbial control of insect pests. It discusses the fungi Beauveria bassiana, Metarhizium anisopliae, Verticillium lecanii, Paecilomyces fumosoroseus, and Hirsutella thomsoni. For each fungus, it describes the target pests, mass production methods, and field application procedures. The document emphasizes that these entomopathogenic fungi are effective alternatives to chemical pesticides for controlling agricultural insect pests while causing less damage to the environment.
- Insects have evolved symbiotic relationships with bacteria and other microorganisms over 250 million years. These endosymbionts can be found inside insects' cells, between cells, and in their guts.
- Endosymbionts play important roles in insect nutrition, defense, reproduction, and environmental adaptation. For example, Buchnera provides essential amino acids to aphids.
- Wolbachia is one of the most common endosymbionts and can manipulate insect reproduction through mechanisms like cytoplasmic incompatibility, parthenogenesis, feminization, and male-killing. Studying endosymbionts enhances understanding of evolution, disease control, and biocontrol applications
This document provides information about microbial biopesticides, specifically entomopathogenic bacteria, viruses, and fungi. It begins with an introduction to microbial control and defines entomopathogens. It then discusses the history, classification, mode of action, symptoms, and target pests of entomopathogenic bacteria including Bacillus thuringiensis. Next, it covers entomopathogenic viruses including classification, examples, and mode of action. Finally, it summarizes entomopathogenic fungi including some of the most common types, their history of use, mode of action, and toxins produced.
SEROLOGICAL METHODS FOR DETECTION OF PLANT PATHOGENSHARISH J
This document discusses serological methods for detecting plant pathogens. It explains that serodiagnosis involves inducing an immune response in an animal to produce antibodies against a pathogen's antigens. These antibodies can then be used to detect the presence of the pathogen. The document describes several serological testing methods including ring interface tests, microprecipitin tests, double diffusion tests, ELISA, immunosorbent electron microscopy, and immunofluorescent staining. It concludes that serodiagnosis is a sensitive tool for identifying pathogens, detecting infections, and quantifying crop diseases.
Gene for gene system in plant fungus interactionVinod Upadhyay
1. Plant-fungus interactions can be characterized by gene-for-gene systems where a plant resistance gene corresponds to a fungal avirulence gene. Vertical or race-specific resistance follows this pattern and is not durable due to high selection pressure.
2. R proteins in plants recognize specific pathogen effectors or avirulence proteins through direct or indirect models. Direct models involve recognition of effectors by R protein receptors. Indirect models involve the effector targeting or modifying a host protein that is then recognized by the R protein.
3. Understanding gene-for-gene systems and how plants recognize pathogens at the molecular level can enable new strategies for disease control through deployment of resistance genes and exploitation of avirulence
Plant immunity towards an integrated view of plant pathogen interaction and i...Pavan R
This document discusses plant immunity and pathogen interactions. It provides an overview of the different forms of plant resistance including antipathy, hindrance, and defense. It describes the phases of plant immunity including PAMP-triggered immunity, effector-triggered susceptibility, and effector-triggered immunity. It also discusses various defense responses in plants against pathogens such as stomatal closure, ion fluxes, oxidative burst, role of phytohormones, hypersensitive response, and systemic acquired resistance. Finally, it summarizes some breeding and biotechnological strategies used to induce resistance in plants like manipulating PAMP receptors, gene pyramiding, use of resistance genes and antifungal fusion proteins, and utilization of phytoalexins.
1. The document discusses the morphology, replication, assembly and architecture of plant virus genomes. It describes the different shapes that plant virus particles can take including rod-shaped, isometric and geminivirus particles.
2. The tobacco mosaic virus (TMV) genome is discussed in detail. The TMV particle is a rigid helical rod consisting of RNA and coat proteins. The coat proteins assemble around the RNA to form the distinctive shape.
3. Assembly of the TMV virus involves initial interactions between coat proteins and RNA near the origin of assembly site, followed by rapid extension in the 5' direction and slower extension in the 3' direction through addition of protein subunits and disks.
Role of microbial toxins in plant pathogenesisansarishahid786
This document discusses the role of microbial toxins in plant pathogenesis. It defines toxins as metabolites excreted or released by pathogens that damage host cells. Toxins are classified based on their source and specificity. Host-specific toxins only affect a pathogen's host, while non-host specific toxins can damage unrelated plants. Toxins disrupt cell permeability, metabolic processes, and growth regulation, injuring and killing host cells. They play an important role in disease development and symptom expression.
This document discusses terminology related to virus transmission by vectors and different types of virus-vector relationships.
1. It defines terms like acquisition access period, acquisition feeding period, inoculation access period, inoculation feeding period, and transmission threshold that describe the process of a vector acquiring and transmitting a virus.
2. It describes three main types of virus-vector relationships: non-persistent, semi-persistent, and persistent. Non-persistent viruses are stylet-borne and lost quickly. Semi-persistent viruses persist for 10-100 hours in the foregut. Persistent viruses circulate and may multiply in the vector.
3. Within persistent viruses, it further distinguishes circulative non-propagative
The document provides an overview of different types of entomopathogenic microbes (viruses, bacteria, fungi, nematodes, protozoa) used for insect management. It discusses the history, mode of action, symptoms caused, and examples of specific microbes used to control various insect pests for different crops. These include Bacillus thuringiensis for lepidopteran larvae, Beauveria bassiana for sucking pests, Metarhizium anisopliae for beet armyworm and rhinoceros beetle, Steinernema carpocapsea for soil-dwelling insects, and Nosema locustae for grasshoppers. The advantages of using entomopathogenic
This document summarizes systemic acquired resistance (SAR) in plants. It discusses that SAR is a defense response activated by pathogens that results in long-lasting, broad-spectrum resistance in distant parts of the plant. The key points are:
- SAR involves accumulation of salicylic acid and pathogenesis-related proteins in distant, uninfected tissues which provides resistance against a wide range of pathogens.
- It is activated after an initial infection causes cell death and necrosis, and involves mobile signaling molecules like methyl salicylate that transmit the defense signal systemically.
- SAR protects against future infections by viruses, fungi, bacteria and activates genes that encode antimicrobial pathogenesis-related proteins.
Pathogenesis-related (PR) proteins are a diverse group of plant proteins that are produced in greater amounts when plants are infected by pathogens or exposed to stress. There are at least 14 families of PR proteins that differ in their functions, properties, and modes of action. Some key PR proteins include PR1, PR2, and PR3. PR1 proteins have antifungal properties and may disrupt fungal membranes. PR2 are β-1,3-glucanases that degrade fungal cell walls. PR3 are chitinases that break down chitin in fungal cell walls, weakening the walls and killing fungi.
Plant microbe interaction by dr. ashwin chekeAshwin Cheke
PLANT MICROBE – INTERACTIONS AND THEIR MUTUAL BENEFITS IN ENHANCING SOIL HEALTH AND AGRICULTURAL PRODUCTION ,
IT ALSO INCREASE CROP PRODUCTIVITY AND IMPROVE SOIL HEALTH
This document discusses induced systemic resistance (ISR) in plants. It provides historical context on studies of induced resistance dating back to the late 1800s. ISR is defined as a phenomenon where treatment with certain chemicals or pathogens activates a plant's defenses throughout the plant. Key findings include:
- ISR is activated by rhizobacteria and involves jasmonic acid and ethylene signaling rather than salicylic acid signaling as in systemic acquired resistance.
- Several bacteria, fungi, chemicals, and elicitors are reported to induce ISR through different signaling pathways and defense responses.
- Further research is needed to fully understand ISR signaling and apply it effectively in fields to control plant diseases.
Rohit Jadhav presented on microbe-plant interactions. Key points include:
- Cyanobacteria and rhizobia have symbiotic relationships with plants, fixing nitrogen.
- Microbes in the rhizosphere and rhizoplane interact with plant roots, satisfying nutritional needs for both.
- Rhizosphere microbes can positively impact plants by nutrient solubilization or negatively through immobilization.
- Legumes form root nodules with rhizobia like Rhizobium spp. and Bradyrhizobium spp. to fix atmospheric nitrogen.
- Some non-legumes interact with nitrogen-fixing cyanobacteria and Frankia bacteria inside root nodules.
-
This document discusses techniques for engineering bacteriophages (phages) to enhance their potential as antimicrobial agents. It describes various methods for genetically modifying phage genomes, including homologous recombination, recombineering, and rebuilding genomes in vitro or in yeast. Synthetic phages have been engineered with broader host ranges or the ability to deliver genes conferring antibiotic sensitivity. Phage lysins have also been developed as antimicrobials targeting pathogens like MRSA. Overall, the document outlines how phage engineering is an area of active research with applications for treating antibiotic-resistant bacteria.
Bacterial pathogens of plants have specialized properties that allow them to infect plants. They parasitize plant cells and cause cell death. Important virulence factors include toxins, extracellular polysaccharides, and degradative enzymes. Bacterial pathogens use type III secretion systems and effector proteins to manipulate plant cells and cause disease symptoms. The interaction between bacterial effectors and plant resistance proteins determines if the interaction is compatible and leads to disease, or incompatible and triggers a hypersensitive response.
Bacteriophage therapy for antimicrobial resistant and biofilm forming [Autosa...kamal shrestha
This document discusses bacteriophage therapy as a potential treatment for antibiotic-resistant and biofilm-forming bacteria. It provides background on antibiotic resistance and biofilms, how they form and confer resistance. Bacteriophages are introduced as viruses that infect and replicate within bacteria. The history of bacteriophage therapy is covered, along with its advantages over antibiotics in being non-toxic and specifically targeting bacteria. Recent advances aim to improve efficacy, such as using cocktails of phages with broader host ranges or genetically modifying phages. Overall, the document argues that bacteriophage therapy shows promise as an alternative to antibiotics for resistant bacterial infections.
Bacteria use quorum sensing to coordinate group behaviors by producing and detecting signaling molecules called autoinducers. When the concentration of autoinducers surpasses a threshold level, it triggers gene expression in the entire population. This process allows bacteria to act as a group at high cell densities. Quorum sensing regulates behaviors like virulence, biofilm formation, and bioluminescence. It is mediated by acyl-homoserine lactones in gram-negative bacteria and modified peptides in gram-positive bacteria. Inhibiting quorum sensing is a potential approach to attenuating bacterial virulence without killing the bacteria.
Introduction, Potato virus A, Viral Infection, Replication, movem.docxnormanibarber20063
Introduction, Potato virus A, Viral Infection, Replication, movement within cells and cell-to-cell transport, Phloem transport, Transport regulations, Potyviral movement proteins, 16 Virus evolution, Plant defense against viruses, RNA silencing, Primary VIGS, 18 Secondary VIGS and systemic silencing, Recovery and dark green islands, Viral suppression of RNA silencing, miRNA and silencing suppressors, Vectors for virus induced gene silencing,
After the above topics write abput GTP binding proteins in pva infection, or ras like proteins in plants and its defence mechanism against poty virus A.
Im attaching materials and methods also. Write them ( description of menthods and leave space for materials) also as it is in the plant virology report. Need another 5 pages.
Total 20-25 pages writing needed latest on Sunday 26.03.2017
Thanks
If any doubts email me at [email protected]
Find me in facebook at shiva manne or [email protected]
These are the topics u can write. You can use the attached thesis file kappa file to write.
I need it exactly like that but with different references and ofcourse u can use some of them.
Need plagiarism free writing
Need all articles and reference pages u used for writing.
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Study on the role of GTP Binding Protein of the Infected Plants in PVA Infection by Virus Induced Gene Silencing
Ras-related protein Rab1a
OBJECTIVES
To examine the role of GTP binding protein which was only found in PVA infected nuclei, in PVA infection by virus induced gene silencing by comparing infected and un-infected plants in Nicotiana benthamiana
To check the RNA levels in the inoculated leaves using quantitative real time PCR.
No silencing found in the controlled and infected plants.
Gene silencing (Rab1a) doesnt or have negligible effect on the poty viral infection.
GTP binding ras protein may help in the viral infection which will be proved by the gene silencing and qPCR.
HYPOTHESIS
GTP binding proteins are a set of family proteins which are very important in various metabolic processes.
They are also associated with nuclear-cytoplasmic trafficking
A recent study showed that a small specific GTP binding protein is found in the nucleus of PVA infected potato plant, whereas there is no proteins in the control plant.
When this protein sequence is searched for the similarity, it is found that there is a similar protein in Nicotiana benthamiana.
In this study, we examine the role of this small protein in PVA infection.
METHODS
RNA EXTRACTION & cDNAsynthesis
PCR AMPLIFICATION
RESTRICTION DIGESTION , LIGATION AND TRANSFORMATION
COLONY PCR
PLASMID ISOLATION AND DNA SEQUENCING
AGRO TRANSFORMATION (GV3101 + psoup)
PRESENT WORK
Growing plants
Constructs preparation:
i) GV3101+PDS
ii) GV3101+empty
iii) GV3101+ insert
iv) GV3101+PVA-gfp
Infiltration
THANK YOU
1
Interactions of Potato virus A with Host
Plants: Recombination, Gene Silencing
and Non-Hypersensitive Resistance
El.
This document discusses insect-resistant crops, including how genes from microorganisms, plants, and animals can confer insect resistance when introduced into crop plants. It covers various types of insect-resistant crops like Bt corn, rice, and cotton that have been commercialized. While insect-resistant crops can reduce pesticide usage, some have concerns about their safety and impact. The technology continues to advance as new genes are discovered and combined to target more pests and prevent insect resistance.
Mycoplasmas are the smallest and simplest self-replicating bacteria .These microorganisms lack a rigid cell wall and are bound by a single membrane, the plasma membrane. The lack of a cell wall is used to distinguish these microorganisms from ordinary bacteria and to include them in a separate class named Mollicutes. Most human and animal mollicutes are Mycoplasma and Ureaplasma species of the family Mycoplasmataceae. Because mycoplasmas have an extremely small genome, these organisms have limited metabolic options for replication and survival. The smallest genome of a self-replicating organism known at present is the genome of Mycoplasma genitalium (0.58 Mb). Owing to their limited biosynthetic capabilities, most mycoplasmas are parasites exhibiting strict host and tissue specificities. The mycoplasmas enter an appropriate host in which they multiply and survive for long periods of time. These microorganisms have evolved molecular mechanisms needed to deal with the host immune response and the transfer and colonization in a new host. These mechanisms include mimicry of host antigens, survival within phagocytic and nonphagocytic cells, and generation of phenotypic plasticity. The major question is whether mycoplasmas cause damage to the host cells and to what extent the damage is clinically apparent. Mycoplasmas have long resisted detailed analyses because of complex nutritional requirements, poor growth yields, and a paucity of useful genetic tools. Although questions still far outnumber answers, significant progress has been made in identifying the mechanisms by which mycoplasmas interact and damage eukaryotic host cells. Many animal mycoplasmas depend on adhesion to host tissues for colonization and infection. In these mycoplasmas adherence is the major virulence factor, and adherence-deficient mutants are avirulent. Primary interactions between the host and mycoplasma cells occur through cell surface adhesins produced by the mycoplasma. The adhesins have been characterized in only a limited number of mycoplasmas, and while there are homologs of the characterized adhesins in some other mycoplasmas, it is clear that different molecules and structures may be involved in adhesion in different species.
Agrobacterium tumefaciens is a soil bacterium that causes crown gall disease in plants by transferring a segment of DNA (T-DNA) from its tumor-inducing plasmid into the plant genome. The T-DNA encodes genes that result in tumor formation. Virulence genes on the plasmid and bacterial chromosome are required for T-DNA processing, transfer to the plant cell, and integration into the plant nuclear genome, with key roles played by VirD2 and VirE2 proteins. Understanding this natural form of horizontal gene transfer between domains has provided insights into intracellular transport mechanisms.
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2) The C-terminal domain of HrpZ1 is necessary and sufficient for binding to plant membranes and stimulating immunity responses, but not for pore formation.
3) Insertional mutations in the C-terminal domain disrupt HrpZ1's ability to activate immunity, suggesting this domain contains motifs recognized by plant
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Cereal rust fungi are pathogens of major importance to agriculture, threatening cereal production worldwide. Targeted breeding for resistance, based on information from fungal surveys and population structure analyses of virulence, has been effective. Nevertheless, breakdown of resistance occurs frequently and continued efforts are needed to understand how these fungi overcome resistance and to determine the range of available resistance genes. The development of genomic resources for these fungi and their comparison has released a torrent of new ideas and approaches to use this information to assist pathologists and agriculture in general. The sequencing of gene transcripts and the analysis of proteins from haustoria has yielded candidate virulence factors among which could be defence-triggering avirulence genes. Genome-wide computational analyses, including genetic mapping and transcript analyses by RNA sequencing of many fungal isolates, will predict many more candidates (Bakkeren et al., 2012)
Dissecting the mechanisms of host-pathogen systems like wheat-rust, including pathogen counter-defenses will ensure a step ahead towards understanding current outcomes of interactions from a co-evolutionary point of view, and eventually move a step forward in building more durable strategies for management of diseases caused by fungi (Hadrami et al.,2012)
Exploitation of endophytic fungi for plant disease management
Introduction
Plant- Endophytic fungi interaction
Diversity of endophytic fungi in plants
Colonization
Endophytic fungi : Mechanism
Case studies
Conclusion
Future aspects
Endophytic fungi in disease resistance (Latz et al., 2018)
Antibiotics produced by fungal endophytes
Plant immune defense system
Lytic enzyme secretion
Endophytic fungi in stress tolerance
For centuries, humans have searched for crop plants that can survive and produce in spite of insect pests.
Knowingly or unknowingly, ancient farmers selected for pest resistance genes in their crops, sometimes by actions as simple as collecting seed from only the highest-yielding plants in their fields.
With the advent of genetic engineering, genes for insect resistance now can be moved into plants more quickly and deliberately.
Bt technology is only one example of ways genetic engineering may be used to develop insect-resistant crops now and in the future.
This document discusses using paratransgenesis to combat malaria. It describes engineering the symbiotic bacteria Pantoea agglomerans from mosquito midguts to secrete proteins that kill Plasmodium parasites. Experiments show the engineered bacteria proliferate in mosquitoes, efficiently secrete anti-Plasmodium proteins, and reduce parasite levels in mosquitoes by 68-84% without impacting mosquito lifespan. The document concludes that using P. agglomerans to deliver multiple antimalarial proteins is an effective and resistance-proof strategy to block malaria transmission.
Bacteriophages come in different sizes and shapes but most of them.docxrock73
Bacteriophages come in different sizes and shapes but most of them have the same basic features: a head or capsid and a tail. A bacteriophage’s head structure, regardless of its size or shape, is made up of one or more proteins which protectively coats the nucleic acid. Though there are some phages that don’t have a tail, most of them do have one attached to its head structure.
How Bacteriophages Work
n oder to infect a host cell, the bacteriophage attaches itself to the bacteria’s cell wall, specifically on a receptor found on the bacteria’s surface. Once it becomes tightly bound to the cell, the bacterial virus injects its genetic material (its nucleic acid) into the host cell. Depending on the type of phage, one of two cycles will occur – the lytic or the lysogenic cycle. During a lytic cycle, the phage will make use of the host cell’s chemical energy as well as its biosynthetic machinery in order to produce phage nucleic acids (phage DNA and phage mRNA) and phage proteins. Once the production phase is finished, the phage nucleic acids and structural proteins are then assembled. After a while, certain proteins produced within the cell will cause the cell wall to lyse, allowing the assembled phages within to be released and to infect other bacterial cells.
Viral reproduction can also occur through the lysogenic cycle. The main difference between the two types of cycles is that during lysogeny, the host cell is not destroyed or does not undergo lysis. Once the host cell is infected, the phage DNA integrates or combines with the bacterial chromosome, creating the prophage. When the bacterium reproduces, the prophage is replicated along with the host chromosomes. Thus, the daughter cells also contain the prophage which carries the potential of producing phages. The lysogenic cycle can continue indefinitely (daughter cells with prophage present within continuing to replicate) unless exposed to adverse conditions which can trigger the termination of the lysogenic state and cause the expression of the phage DNA and the start of the lytic cycle. These adverse conditions include exposure to UV or mutagenic chemicals and desiccation.
http://phages.org/bacteriophage/
Patients in hospitals, especially those on breathing machines, those with devices such as catheters, and patients with wounds from surgery or from burns are potentially at risk for serious, life-threatening infections.
n hospitals, where the most serious infections occur, Pseudomonas can be spread on the hands of healthcare workers or by equipment that gets contaminated and is not properly cleaned.
https://www.cdc.gov/hai/organisms/pseudomonas.html
P. aeruginosa can develop resistance to antibacterials either through the acquisition of resistance genes on mobile genetic elements (i.e., plasmids) or through mutational processes that alter the expression and/or function of chromosomally encoded mechanisms. Both strategies for developing drug resistance can severely limit the therapeutic ...
I reviewed several manuscripts, books, grants and project proposals. This is one of the paper I reviewed recently published in Plant Biotechnology Journal
Genetic engineering & new technologies their progress in Integrated Pest Man...Thims957
Genetic engineering and new technologies have made progress in integrated pest management (IPM) programs but also face limitations. Technologies like inserting insect-resistant genes from Bacillus thuringiensis into plants or using genetic engineering to optimize the speed at which pathogens kill pests have shown promise. However, producing recombinant pathogens faster-killing hosts results in fewer pathogen bodies produced. Additionally, viruses must be ingested to work and can be deactivated by sunlight or rain. Fungal pathogens are intolerant of low humidity or high heat. While biotechnology has improved crops through herbicide and insect resistance, developing transgenic methods that are economical at a large scale remains a challenge.
Higher plants contain nutrients that bacteria can access through openings like stomata. Gram-negative bacteria like Pseudomonads and Enterobacteria specialize in colonizing plant tissues. These apoplastic colonizers are often pathogens that cause diseases. Plants have evolved two lines of defense: pattern-triggered immunity in response to microbe-associated molecular patterns, and effector-triggered immunity in response to bacterial effectors through resistance proteins. Bacteria deliver effectors into plant cells through type III secretion systems like Hrp, and plants recognize specific effectors through corresponding resistance genes in a gene-for-gene interaction.
Similar to Bacterial symbionts in vector and its role in plant virus transmission (20)
The document summarizes the key national forest policies of India from 1855 to 1988 in 3 sentences:
The earliest national forest policy of 1855 focused on restricting exploitation of forests and establishing the Forest Department, while later policies in 1894 and 1952 aimed to balance land use and fulfill revenue needs through sustainable forest management. The 1988 policy emphasized maintaining ecological balance, meeting energy demands, involving local communities, and protecting forests from diversion and industries.
The document discusses the objectives, importance, and types of forests in India according to silviculture. The key objectives of silviculture include raising more economically valuable species, increasing production volume and quality, reducing rotation periods, and afforestation. Silviculture is important as it produces raw materials, increases forest cover for wildlife, regulates water cycles, prevents soil erosion and floods, and creates jobs. India's forests are classified into 16 types based on factors such as climate and vegetation. The major forest types include tropical wet evergreen, moist deciduous, dry deciduous, thorn, and coniferous pine forests.
Agroforestry is defined as a land use system that integrates trees, crops, and animals in a scientifically, ecologically, and socially sustainable way. It aims to increase overall land productivity through the combined production of various components. Some key attributes of agroforestry systems are that they seek to maintain or increase total outputs, sustainably conserve resources, and be adoptable by local farmers. There are many types of agroforestry systems defined by their structural composition, functions, socioeconomic level, and suitable ecology. Examples include agrisilviculture, alley cropping, and silvipasture.
This document defines key terms related to forestry such as forest, forestry, forest cover classifications including very dense forest, moderately dense forest, open forest and scrub. It provides data on India's forest cover and classifications. It also outlines important forest laws and research institutes in India. Significant scientists involved in forest conservation are profiled like Dietrich Brandis, Hugo Woods, Salim Ali and Wangari Maathai. Important days related to forestry are also listed.
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The document discusses suitable tree species for different zones in Tamil Nadu, India. It identifies tree species that require light or shade and can be used for pollarding. Examples of commonly used exotic tree species introduced from other regions include eucalyptus, acacia auriculiformis, and cryptomeria japonica. The document then lists suitable agroforestry practices for seven different zones in Tamil Nadu, including tree species like delonix elata, pongamia pinnata, bamboo, hardwickia binata, and rubber trees.
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This document discusses suitable agroforestry practices for the different agroclimatic zones of Tamil Nadu, India. It describes the dominant tree species, major crops, soil types, rainfall, and common agroforestry practices for each zone. The seven zones covered are: 1) Northeastern, 2) Northwestern, 3) Cauvery Delta, 4) Western, 5) Southern, 6) High Rainfall, and 7) Hilly. Common agroforestry practices include bund planting, intercropping, woodlots, boundary planting, and home gardens. The document emphasizes that agroforestry systems meet requirements for food, fodder, timber and income.
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Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
Current Ms word generated power point presentation covers major details about the micronuclei test. It's significance and assays to conduct it. It is used to detect the micronuclei formation inside the cells of nearly every multicellular organism. It's formation takes place during chromosomal sepration at metaphase.
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
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high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
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hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
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Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
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Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...
Bacterial symbionts in vector and its role in plant virus transmission
1. Bacterial symbionts in vector and its role
in plant virus transmission
1
B. Sangeetha, (Ph. D Scholar)
Dr. P. Renukadevi, Assistant Professor (Plant Pathology)
Dr. V. G. Malathi, Adjunct Professor (Plant Virology)
Department of Plant Pathology,
Tamil Nadu Agricultural University, Coimbatore, India.
2. Content
Genesis of symbionts
Symbionts in Aphid
Symbionts in whitefly
Symbionts in mealybug , leafhopper , thrips
2
3. Symbiosis:
Symbiosis origin - Greek means together
Permanent association between two or more
distinct individuals , atleast during a part of their life cycle.
Symbionts:
An organism in a symbiotic relationship.
Examples: Fungi , Baceriophage , Lichens , mycorrhiza
Harpreet Singh Raina et al ., 2015
3
4. Nearly 100 years ago
Paul Buchner from
Germany documented
array of both
endosymbiotic fungi and
bacterial associates of
arthropods
The title of the book
“Endosymbiosis of
animals with plant
microorganisms”.
Genesis of bacterial symbionts
4
5. 1967- Lynn Margulis 'endosymbiont theory'.
1994- Jonnes F.J -First report of endosymbiotic
bateria associated with PLRV by Myzus persicae
1998 -A. E. Douglas -Nutritional Interactions in
Insect-Microbial Symbioses: Aphids and Their
Symbiotic Bacteria Buchnera
5
Jonnes F.J et al ., 1994
10. Insect feeds on phloem sap which, although is rich in carbohydrates,
but lacks essential amino acids.
Lacking nutrients are expected to be compensated by the bacterial
community harboured by the insect.
Secondary endosymbionts -confer them :
Temperature tolerance
Increased resistance to parasitic wasps
Increased resistance to insecticides
Sex determination
Providing fitness benefits
Causing host plant specialization
Harpreet Singh Raina et al ., 2015
10
Role and functions
11. • A bacteriocyte (Greek - bacteria cell) also called a
mycetocyte - insect groups such as aphids, german
cockroaches and weevils.
• Endosymbiotic bacteria such as Buchnera species,
which provide essential aminoacids and other
chemicals to their host.
• Bactriome
Baumann et al, 2000
TEM of aphid bacteriocyte
Larger - Buchnera
Smaller-Hamiltonella defensa
11
12. Aphids and its hosts
Aphids Hosts plants
Aphis fabae Bean
A. craccivora Cowpea
Acyrthosiphon pisum Pea
Rhopalosiphum padi Maize
Metopolophium dirhodum
Sitobion avenae
Oats
12Johannes F. J. M. van den Heuvel et al ., 1994
15. Aphid species having endosymbionts
Vector Virus Endosymbionts
Myzus persicae PLRV
BWYV
Buchnera aphidicola
Acyrthosiphon pisum PEMV
BLRV
BYDV
Buchnera aphidicola
Hamiltonella , Regiella ,
Serratia , Rickettsia ,
Spiroplasma
Pentalonia nigronervosa BBTV Buchnera aphidicola
Wolbachia
15
Johannes F. J. et al ., 1994
16. Charactization of Endosymbiont
Total DNA extraction
PCR by using 16S ribosomal DNA sequences
Clones and Sequencing
Confirmation
16Caroline De Clerck et al ., 2015
18. GroEL
GroEL belongs to class of proteins called Chaperonin.
They are ring shaped protein complexes essential in the
cell mediating ATP dependent polypeptide folding.
Costa Gourgopolas (1970) isolated a mutant of E.coli
that were unable to support the Lamda phage.
E.coli gene responsible for this phenotype was given the
name GroEL- assembly aiding function.
18
Adi Kliot and Murad Ghanim 2013
19. Contd….
Van den Henvel 1994 Myzus persicae protein extracts
Out of five proteins one bind the CP antibody.
The protein was present in high concentration.
This protein was homologous to E.coli well described
protein called GroEL.
Which was previously called symbionin- production
by endosymbionts of pea aphid Acyrthosiphon pisum
now referred to as (MpBsym) Myzus persicae -
Buchnera GroEL
19
20. Role of bacterial chaperones in virus
transmission
20
Virion assembly
stage within the
host
Ability to bind –
proteins of
different
structure
Adi Kliot and Murad Ghanim 2013
21. Role of symbionin of Buchnera spp in
aphid
The aphid endosymbiont, Buchnera spp., is known to
produce copious amounts of the protein symbionin (a
homolog of Escherichia coli GroEL) which binds to
luteoviruses and other viruses that are transmitted in a
circulative, nonpropagative manner .
Symbionin binds to virus in the hemolymph it protects
the virus from the aphid immune system.
Alberto Fereres and Benjamin Raccah.,2015
21
22. Potato leafroll virus (PLRV) is a single-stranded RNA
virus that belongs to the luteovirus group.
PLRV particles also bind to native symbionin ,these
virus particles when acquired into the haemocoel of
an aphid interact with symbionin.
22
23. Assays for the study
Monoclonal antibody raised for PLRV
Anti-idiotypic antibodies (AiAbs) were raised to
PLRV-specific MAbs (monoclonal antibodies) virus
(BNYVV)
23
24. Two-dimensional SDS PAGE
24
(a) Two-dimensional profile of whole-body proteins of M.
persicae stained with CBB. (b,e) Immunoblots of two-
dimensional Uv separated whole-body proteins of
M.persicae incubated with purified PLRV particles and
AiAb (c)
25. Bacterial symbionts in Myzus persicae
25
A B
Immunogold-labelling of the
primary endosymbiont (e) in the
mycetocyte (m) of M. persicae
using AiAb.
Cross-section through a 1-day-old
nymph
Endosymbiont in mycetocyte
26. ELISA to determine binding in vitro of vector-
borne plant viruses to native p63 of M. persicae
26
All viruses were applied at 10 µg/ml PBS-Tween.
1-PLRV
2-BWYV
3-BICMV
4-TSWV
5- CPMV
6-BNYVV
27. Effect of Tetracycline treatment
27
Western blots of haemolymph proteins probed with anti-p63 antibodies, and of
whole-body homogenates of aphids probed with anti-PLRV antibodies. Tc,
tetracycline-treatednymphs; Co, control nymphs, not treated with the antibiotic.
28. Luteovirus particles are composed of two types of
capsomeres.
The predominant one is CP .
Another minor one, believed to be on the surface of
the virion, is the read-through (RT) protein.
Gray et al., 2014
Beet western yellows virus - Interaction
with Buchnera
28
29. Beet western yellows virus
BWYV engineered to be encapsidated with CP alone (with no
RT protein subunits) did not bind to Buchnera GroEL.
in vivo studies showed that BWYV virions lacking the RT
protein were significantly less persistent in the haemolymph
than were virions with the RT protein.
This led to the hypothesis is that the interaction between
Buchnera GroEL and the RT protein protects the virus from
rapid degradation in the haemolymph.
Comparison of the RT domain from different luteoviruses and
PEMV revealed several conserved amino acid residues that
may be important for the interaction with Buchnera GroEL
29
31. Diverse population of secondary symbionts in
insects -(FISH)
A–B: FISH of Arsenophonus (yellow)
and Portiera (red) in T. vaporariorum under
bright field (A) and dark field (B).
C–D: Fritschea (blue) and Portiera (red) in
NW2
E–F: Hamiltonella (green) and Portiera(red) in
MEAM1 .
G–H: Rickettsia (blue) and Portiera (red) in
MEAM1
I–J: Cardinium (blue) and Portiera (red) in T.
acaciae .
K–L: Wolbachia (blue) in B. tuberculata .
31
32. Presence of secondary endosymbionts in
B. tabaci
P-pleomorphic endosymbionts
C-coccoid endo symbionts
immunogold labelling with
antibody to Buchnera GroEL
protein antibody.
In whiteflies fed on antibody to
protein TYLCV titre declined.
Morin et al ., 1999
32
35. B. tabaci cryptic species China 1 ( B. tabaci biotype ZHJ3) additional
bacterium which belongs to the Alphaproteobacteria subdivision of the
Proteobacteria and has a close relationship with human pathogens of the
genus Orientia was identified . Orientia like organism (OLO)
New endosymbiont identified in China-1 population
35
36. Different Bemisia tabaci biotypes harbour different
secondary symbionts.
Morin et al ., identified GroEl analogue of Buchnera in B
biotype of B. tabaci
Whiteflies fed with antibodies to Buchnera protein . No
TYLCV DNA was detected .
Physical interaction between GroEL and TYLCV –CP was
demonstrated by TEM studies showed (immunogold)
binding with Buchnera not with Portiera.
Yeast hybrid test ,I –PCR ,
Q and B biotype Spain
36
38. Secondary symbiont Rickettsia in China 1
biotype of whitefly
Infection with Rickettsia spp., a facultative endosymbiont of
whiteflies, altered TYLCV-B. tabaci interactions.
B. tabaci strain infected with Rickettsia acquired more
TYLCV from infected plants, retained the virus longer, and
exhibited nearly double the transmission efficiency compared to
an uninfected B. tabaci strain with the same genetic background.
Adi Kliot et al., 2014
38
39. Representative double FISH of TYLCV (red) and Rickettsia
(green) in B. tabaci midguts dissected from Rick+ female
whiteflies collected from TYLCV-infected tomatoes.
Adi Kliot et al., 2014
FISH of TYLCV (red) and Rickettsia(green) in B. tabaci midguts
dissected from Rick+ female whiteflies collected from TYLCV-infected
tomatoes.
39
40. B biotype - Middle East-Minor Asia 1 (MEAM1)
Q biotype -Mediterranean (MED)
40
41. Different Q types
Israeli Q lacks Hamiltonella - cannot effectively transmit
–TYLCV
Chinese Q contains Hamiltonella- can efficiently
transmit TYLCV to tomato plants.
41
42. 42
Percentage of H1 vs. H2 Q whiteflies (Bemisia tabaci) that acquired TYLCV
after 13 acquisition access periods (AAPs) as determined by conventional PCR.
43. 43
Relative amount of TYLCV (normalized to the host nuclear bactingene) in H1 (black
dots) and H2 (red dots) Q whiteflies (B. tabaci) after 10 acquisition access periods
(AAPs) as determined by q-PCR.
44. Polymerase chain reaction (PCR) and Flourescence in situ
Hybridisation (FISH) commonly used for identification and
localization of bacterial endosymbionts in B. tabaci
44
DNA isolation
16S rRNA sequences
Clone and sequence
Confirmation
Harpreet Singh Raina et al ., 2015
45. 45
Agarose gel electrophoresis of 16S rDNA PCR product of different bacterial
endosymbionts, amplified from total DNA of Bemisia tabaci samples of Delhi
population. (A) Represents PCR results for primary endosymbiont Portiera (1kb). (B)
Wolbachia (650bp). (C) Rickettsia (800bp). (D) Arsenophonus (630bp). (E) Cardinium
(440bp)
Harpreet Singh Raina et al ., 2015
46. 46
FISH staining of different bacterial endosymbionts in whole
mount of B. tabaci using bacteria specific LNA probes.
Localization of (A)Wolbachia
and Portiera.
(B) Localization of Rickettsia
and Portiera.
(C) Localization of
Arsenophonus and Portiera.
(D) Localization of Cardinium
and Portiera
(a) Merged image showing
overlap of Portiera and
respective secondary
endosymbiont.
(b) Presence of Portiera in
bacteriocytes.
(c) Presence of respective
secondary endosymbiont in
bacteriocytes
(d) Phase contrast.
Harpreet Singh Raina et al ., 2015
47. 47
Comparative frequency distribution of different bacterial endosymbionts by
diagnostic PCR and FISH in samples of B. tabaci from different locations.
48. 48
Western flower thrips, Frankliniella occidentalis
(Thysanoptera:Thripidae)
Erwinia - facultative symbiont De Vries et al., 2001
Bacterial symbionts of thrips
49. Cont..,
First instar larvae -take up bacteria from the leaves or
from the faeces or saliva deposited by other thrips.
Most very young first instar thrips larvae are not
infected with gut bacteria (prevalence of 20%)
Second larval stage, are 100% infected.
Bacteria are not directly transmitted from mother to
offspring, but larvae acquire bacteria from the leaves
right after they hatch.
49
De Vries et al., 2001
51. Western flower thrips preference for thrips damaged leaves
over fresh leaves enables uptake of symbiotic gut bacteria
51
52. (%)Percentage of adult western flower thrips that transmitted Tomato spotted
wilt virus.
Symbiotic thrips (Sym).
Bacteria-free thrips aposymbiotic (Apo). (Tetracycline)
The percentage of adults that transmitted the virus determined by recording the
incidence of local lesions that developed on a Petunia leaf disk fed on by an adult
for two days. Transmission – percentage of thrips that successfully transmitted
virus.
52
53. No effects of symbiotic gut bacteria of thrips on
tospovirus transmission efficiency
53
54. Bacterial symbionts in mealybugs
Tremblaya princeps
Plant sap-sucking insects with an obligate association with
prokaryotic endosymbionts .
Particular endosymbionts are acquired through vertical, maternal
transmission - stored within the mealybug’s body cavity in
aggregates of specialized cells called bacteriocytes.
Phylogenetic analyses are consistent with an infection of a mealybug
ancestor – precursor endosymbiont followed by the vertical
transmission of the endosymbiont to progeny.
Charles JG et al ., 2006
54
55. Diversity of Bacterial Endosymbionts Associated with
Leafhoppers (Macrosteles )
Endosymbiotic microbiota of the Macrosteles leafhoppers Macrosteles striifrons
and Macrostele sexnotatus
PCR, cloning, sequencing, and phylogenetic analyses of bacterial 16S rRNA
genes identified
Two obligate endosymbionts:
“Candidatus Sulcia muelleri”
“Candidatus Nasuia deltocephalinicola”
Five facultative endosymbionts:
Wolbachia
Rickettsia
Burkholderia
Diplorickettsia
A novel bacterium belonging to the Rickettsiaceae
55Charles JG et al ., 2006
56. 56
(A) Epifluorescence image of the whole abdomen.
(B) Confocal image of the bacteriome. Red, green, and blue signals
indicate “Ca. Sulcia muelleri,” “Ca. Nasuia deltocephalinicola,” and host nuclear
DNA, respectively
Fluorescence in situ hybridization of the endosymbionts “Ca. Sulcia
muelleri” and “Ca. Nasuia deltocephalinicola” within the bacteriomes of the
leafhopper Macrostele striifrons.
Charles JG et al ., 2006
57. Conclusion
We can say that convincing evidence establishing
the role of endosymbionts in the transmission of
plant viruses have been obtained.
So far only in two cases however, the exact
mechanism of how the symbionin helps a virus in
crossing the midgut and salivary gland barrier
leads to be understood.
57
58. Conclusion
The convincing evidence establishing the role of
endosymbionts in the transmission of plant
viruses have been obtained so far only in two
cases .
However the exact mechanism of how the
symbionin helps the virus in crossing the midgut
and salivary gland barrier needs to be
understood.
58
Editor's Notes
Representative double FISH of TYLCV (red) and Rickettsia (green) in B. tabaci midguts dissected from Rick+ female whiteflies collected from TYLCV-infected tomatoes. (A) Two midguts, midgut 1 and midgut 2, are shown with only the green channel for Rickettsia. (B) Same two midguts as in panel A but shown with the red channed for TYLCV. (C) Overlay of panels A and B showing the two channels for Rickettsia and TYLCV. Abbreviations: amg, ascending midgut; dmg, descending midgut; fc, filter chamber; ca, ceca. At least 20 midguts were analyzed using this double FISH analysis method.