This document discusses the structural and biochemical defense mechanisms in plants against pathogens. It begins by introducing that plants lack an immune system like animals but have developed defenses to detect and prevent extensive damage from invading organisms. It then describes structural defenses like waxes, thick cuticles and cell walls that act as pre-existing barriers, as well as post-infection responses like cork layer formation. Biochemical defenses include pre-existing inhibitors and phenolic compounds, as well as induced responses like phytoalexins - toxic antimicrobial substances produced after infection. Overall, the document provides an overview of the key physical and chemical defenses plants have evolved to protect against various fungi, bacteria, viruses and other pathogens.
Transmission of plant viruses can occur horizontally by vectors like insects, contaminated tools, or vertically through propagation materials like seeds or cuttings. There are two main types of transmission: non-persistent and persistent/circulative. Non-persistent viruses are acquired quickly but not retained long in vectors, while persistent viruses have longer acquisition times and retention periods in vectors. Aphids are the most important insect vectors, and can transmit viruses in non-persistent, semi-persistent, or persistent/circulative manners depending on how long they retain the virus. Mechanical transmission under laboratory conditions is also discussed.
Plant - Pathogen Interaction and Disease DevelopmentKK CHANDEL
Plant diseases are the result of infection by any living organisms that adversely affect the growth, development, physiological functioning and productivity of a plant, manifesting outwardly as visible symptoms.
bacteria can enters into plants by different mechanisms and the slides which includes different mode of entries into plants, and this information is also important for students who are preparing for NET exams.
The document discusses plant viruses. It begins by outlining learning objectives about plant virus infections, life cycles, transmission, structures, classification, replication, symptoms, identification, and control. It then provides details on the characteristics of plant viruses, including their non-cellular nature and dependence on host cells. The document discusses plant virus transmission methods, proteins, capsids, classifications, replication cycles for different types of viruses, symptoms, and methods of detection, identification, and control.
plant pathogen interaction
different types of pathogens
gene for gene hypothesis
direct receptor model
Elicitor receptor model
suppersor repressor model
gaurd hypothesis
Plant viruses can move from cell to cell through plasmodesmata with the help of viral movement proteins. Most plant viruses move as ribonucleoprotein complexes containing genomic RNA and viral movement proteins. Systemic spread within the plant occurs through the phloem. Plant viruses are transmitted to new hosts through mechanical means like contaminated tools, insect vectors, seed transmission, grafting, and nematodes. The type of transmission determines the epidemiology and spread of the virus.
Mushrooms provide various health benefits and nutrients. They are low in calories, fat, cholesterol, and sodium. Mushrooms are a good source of protein, vitamins such as riboflavin, niacin, and pantothenic acid. They also contain minerals like potassium, copper, and selenium. Mushrooms have anti-cancer, anti-fungal, anti-bacterial, and anti-oxidant properties. Their polysaccharide content supports immune function. Due to their nutrient composition, mushrooms can be consumed by those with diabetes or heart conditions.
- Phytoalexins are antimicrobial compounds produced by plants after exposure to microorganisms or abiotic stress. They are chemically diverse and fall into classes like terpenoids and alkaloids.
- The concept of phytoalexins was formalized in 1941 after observing that bean tissue produced inhibitory compounds when exposed to a fungal pathogen. Phytoalexins restrict pathogen growth at infection sites.
- Induction of phytoalexins involves MAP kinase signaling cascades and transcription factors like WRKY33 regulating genes in biosynthesis pathways. Camalexin production in Arabidopsis in response to pathogens depends on WRKY33 phosphorylation by MPK3/MPK6.
Transmission of plant viruses can occur horizontally by vectors like insects, contaminated tools, or vertically through propagation materials like seeds or cuttings. There are two main types of transmission: non-persistent and persistent/circulative. Non-persistent viruses are acquired quickly but not retained long in vectors, while persistent viruses have longer acquisition times and retention periods in vectors. Aphids are the most important insect vectors, and can transmit viruses in non-persistent, semi-persistent, or persistent/circulative manners depending on how long they retain the virus. Mechanical transmission under laboratory conditions is also discussed.
Plant - Pathogen Interaction and Disease DevelopmentKK CHANDEL
Plant diseases are the result of infection by any living organisms that adversely affect the growth, development, physiological functioning and productivity of a plant, manifesting outwardly as visible symptoms.
bacteria can enters into plants by different mechanisms and the slides which includes different mode of entries into plants, and this information is also important for students who are preparing for NET exams.
The document discusses plant viruses. It begins by outlining learning objectives about plant virus infections, life cycles, transmission, structures, classification, replication, symptoms, identification, and control. It then provides details on the characteristics of plant viruses, including their non-cellular nature and dependence on host cells. The document discusses plant virus transmission methods, proteins, capsids, classifications, replication cycles for different types of viruses, symptoms, and methods of detection, identification, and control.
plant pathogen interaction
different types of pathogens
gene for gene hypothesis
direct receptor model
Elicitor receptor model
suppersor repressor model
gaurd hypothesis
Plant viruses can move from cell to cell through plasmodesmata with the help of viral movement proteins. Most plant viruses move as ribonucleoprotein complexes containing genomic RNA and viral movement proteins. Systemic spread within the plant occurs through the phloem. Plant viruses are transmitted to new hosts through mechanical means like contaminated tools, insect vectors, seed transmission, grafting, and nematodes. The type of transmission determines the epidemiology and spread of the virus.
Mushrooms provide various health benefits and nutrients. They are low in calories, fat, cholesterol, and sodium. Mushrooms are a good source of protein, vitamins such as riboflavin, niacin, and pantothenic acid. They also contain minerals like potassium, copper, and selenium. Mushrooms have anti-cancer, anti-fungal, anti-bacterial, and anti-oxidant properties. Their polysaccharide content supports immune function. Due to their nutrient composition, mushrooms can be consumed by those with diabetes or heart conditions.
- Phytoalexins are antimicrobial compounds produced by plants after exposure to microorganisms or abiotic stress. They are chemically diverse and fall into classes like terpenoids and alkaloids.
- The concept of phytoalexins was formalized in 1941 after observing that bean tissue produced inhibitory compounds when exposed to a fungal pathogen. Phytoalexins restrict pathogen growth at infection sites.
- Induction of phytoalexins involves MAP kinase signaling cascades and transcription factors like WRKY33 regulating genes in biosynthesis pathways. Camalexin production in Arabidopsis in response to pathogens depends on WRKY33 phosphorylation by MPK3/MPK6.
1. The document discusses the defense mechanisms of plants against plant pathogens, including structural and biochemical defenses.
2. Structural defenses include pre-existing structures like wax, thick cuticles, and thick-walled cells, as well as induced structures like cork layers and tyloses formation in response to infection.
3. Biochemical defenses include pre-existing inhibitors and phenolic compounds, as well as induced responses like phytoalexin production, hypersensitive response, and pathogenesis-related protein synthesis post-infection.
4. Both structural and biochemical defenses work together and are influenced by factors like the plant's age, organ infected, and environmental conditions.
This document discusses the six basic principles of plant disease management: avoidance, exclusion, eradication, protection, resistant varieties, and therapy. It provides details on each principle and methods to achieve it, such as choosing disease-free geographical areas and seed/planting material, quarantines, rouging of infected plants, crop rotation, chemical treatments, and using resistant varieties.
In this presentation you will be learning about the SPOTTED WILT VIRUSES which is caused in TOMATO crop. And also its mode of establishment into the crop, deficiency symptoms, life cycle, life span of the virus, yield losses in that particular crop and at last its MANAGEMENT PRACTICES.
Plant viruses are transmitted from plant to plant in a number of ways.
Transmission of viruses by vegetative propagation.
Mechanical transmission of viruses through sap.
Transmission of viruses by seed.
Transmission of viruses by Pollen.
Transmission of viruses by dodder.
Transmission by vectors.
Viral infections in plants can be controlled through several strategies including using certified seed/plants, controlling weeds that harbor viruses, and insecticide use since most viruses are vector-borne. Transgenic virus resistance involves expressing viral genes including coat proteins, replicases, movement proteins, or antisense RNA to interfere with viral replication or movement. The papaya industry was saved through a transgenic papaya resistant to papaya ringspot virus. While virus resistance holds promise, risks like recombination or heterologous encapsidation must be monitored.
1) Plant viruses use various transmission methods like insects, sap, seed, or nematodes to spread between plants since plants cannot move.
2) Plants have two main antiviral resistance mechanisms: R gene-mediated responses and RNA silencing. R genes confer resistance to specific viruses and trigger cell death and systemic resistance. RNA silencing uses small RNAs to degrade or inhibit viral RNA.
3) These mechanisms sometimes overlap when a viral protein can suppress RNA silencing and also be detected by an R gene product as an Avr protein. This indicates communication between the plant's antiviral defense pathways.
This document discusses various methods of plant virus transmission including mechanical, grafting, seed, insect, nematode, and fungal transmission. It provides details on each method such as the viruses transmitted, vectors involved, and procedures. Mechanical transmission involves sap inoculation using leaf rubbing or pinprick methods. Grafting and dodder transmission are also discussed. Seed and pollen transmission of certain viruses is possible. Insect vectors like aphids, whiteflies, and leafhoppers transmit many plant viruses in a circulative or non-persistent manner. Finally, nematodes and fungi can act as vectors for some viruses.
Bhendi yellow vein mosaic virus was first reported by Kulkarni in the year 1924. It was recorded at Bombay and Srilanka simultaneously. This disease is caused by a ss-DNA virus belongs tot the family Geminiviridae and belongs to the genus Begomovirus
Phytoalexins are toxic chemical compounds produced by plants in response to infection by parasites or pathogens. They act as a defense mechanism against invading fungi or bacteria. Hundreds of phytoalexins have been characterized, mostly in the families Fabaceae and Solanaceae. They are produced through the shikimic acid pathway and are often fungistatic rather than fungicidal. Important phytoalexins include pisatin, phaseollin, glyceollin and gossypol. In addition to their role in plant defense, many phytoalexins have potential health benefits for humans such as antioxidant, anti-inflammatory and anticancer properties.
This document discusses plant disease development. It begins by outlining the objectives and topics to be covered, which include the disease triangle, factors for successful disease development, and stages of disease development. The disease triangle requires the presence of a susceptible host, virulent pathogen, and favorable environment. The factors for disease development include the properties of the pathogen, host, and environment. The stages of disease development are inoculation, penetration, infection, growth and reproduction of the pathogen, and dissemination of the pathogen.
This document discusses the Cauliflower Mosaic Virus (CaMV) and its potential use for gene transfer in plants. CaMV is a plant virus that infects brassica plants like cauliflower and turnips. It has a circular double-stranded DNA genome and is spherical in shape. The 35S promoter from CaMV is commonly used in plant transformation due to its strong constitutive expression in dicots. For gene transfer, foreign DNA can be inserted into the non-essential genes II or VII of CaMV. However, CaMV has limitations for gene transfer due to its limited insertion capacity and loss of infectivity if too many nucleotides are added.
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.
Mechanism of disease control by endophytesPooja Bhatt
The document discusses alternative methods for pest management to address problems with chemical pesticides such as development of resistance and environmental contamination. It suggests that biological control using endophytic microorganisms is a promising alternative as endophytes have antagonistic properties against plant pathogens. Endophytes can inhibit pathogens through direct mechanisms such as hyperparasitism, competition, antibiosis, and lytic enzyme production or indirect induction of host plant resistance. Case studies provide examples of endophytes inhibiting fungal plant pathogens through siderophore production, parasitic growth, and antibiotic compounds.
The document summarizes the life cycle of mushrooms. Mushrooms grow in moist, dark places on decaying organic matter. Their life cycle begins as a spore and progresses through five stages, ending when the fruiting body releases new spores. Key stages include the mycelium, basidium, basidiospore, and basidiocarp. Mushrooms are an important source of protein, vitamins, and minerals. Mushroom farming is common in Nepal and produces around 8-10 tons per day, with oyster and white button mushrooms among the edible varieties grown.
This document summarizes the key principles of plant infection:
1) Penetration is the entry of the pathogen into the host, which can occur directly through the plant surface, through wounds, or through natural openings like stomata, hydathodes, or lenticels.
2) Infection is the establishment of the pathogen within the host plant by procuring nutrients from host cells or tissues.
3) Invasion is the spread of the pathogen within the host, which can be intercellular or intracellular depending on the type of pathogen.
4) Dissemination refers to the spread of the pathogen from one plant to another, which can occur autonomously through soil, seeds, or plant parts,
Chemical control of plant diseases involves using chemicals like bactericides, fungicides, and nematicides to inhibit or kill pathogens. Bactericides rely on copper and treat bacterial diseases. Fungicides disrupt fungal cellular processes and are applied as sprays, dusts, or to seeds. Nematicides like aldicarb kill nematodes. Chemicals are applied through soil treatments, seed treatments, or foliar sprays. While effective, chemicals can harm non-target organisms and accumulate up the food chain.
Bacterial soft rot is caused by pectin-degrading bacteria such as Pectobacterium carotovorum, Dickeya dadantii, and certain Pseudomonas species. These bacteria enter plants through wounds and degrade the pectin between plant cells, causing tissues to break down into a soft, watery rot. Soft rot commonly affects potatoes, carrots, tomatoes, and other vegetables. It starts as water-soaked lesions that enlarge and become soft, mushy, and foul-smelling. Good sanitation and avoiding excess moisture can help manage soft rot by limiting bacterial spread and growth.
Virus infection involves several steps: virus entry into the host cell, uncoating of the viral genome, targeting of viral genes to host cell machinery, genome replication, assembly of new viral components, and release of progeny virus. Key proteins like movement proteins and coat proteins facilitate various stages of the infection process by transporting the viral genome and protecting it. The virus life cycle is dependent on hijacking host cell processes and resources for its replication and spread to new cells.
The document summarizes plant defense mechanisms against pathogens. It discusses both structural and biochemical defenses. For structural defenses, it describes preexisting structures like cuticular wax, thick cuticles, and lignified cell walls that physically block pathogens. It also discusses defense structures that develop after infection, like cell wall thickening, callose deposition, and tissue necrosis. For biochemical defenses, it outlines preexisting inhibitors and lack of nutrients for pathogens. It also describes phytoalexins and other compounds produced after infection, such as phenolic compounds and substances that deactivate pathogen enzymes and toxins. The document provides several examples to illustrate different defense strategies in plants.
Plants have developed structural, chemical, and protein-based defenses against pathogens. Structural defenses include waxy coatings, thick cell walls, and pores designed to limit pathogen entry. Chemical defenses include pre-existing compounds like phenolics and induced responses like phytoalexins and hypersensitive response that are activated post-infection. Together, a plant's layered defenses work to detect, stop, and limit damage from invading pathogens.
This document discusses the defense mechanisms of plants against plant pathogens. It describes two main types of defense mechanisms: structural (morphological) defenses and biochemical defenses. Structural defenses include pre-existing barriers like wax layers and thick cell walls, as well as induced defenses created after infection like cork layers and tyloses formation. Biochemical defenses include both pre-existing compounds like phenolics and induced responses like phytoalexin and PR protein production. The document provides examples of specific defense mechanisms employed by plants in response to various pathogens.
1. The document discusses the defense mechanisms of plants against plant pathogens, including structural and biochemical defenses.
2. Structural defenses include pre-existing structures like wax, thick cuticles, and thick-walled cells, as well as induced structures like cork layers and tyloses formation in response to infection.
3. Biochemical defenses include pre-existing inhibitors and phenolic compounds, as well as induced responses like phytoalexin production, hypersensitive response, and pathogenesis-related protein synthesis post-infection.
4. Both structural and biochemical defenses work together and are influenced by factors like the plant's age, organ infected, and environmental conditions.
This document discusses the six basic principles of plant disease management: avoidance, exclusion, eradication, protection, resistant varieties, and therapy. It provides details on each principle and methods to achieve it, such as choosing disease-free geographical areas and seed/planting material, quarantines, rouging of infected plants, crop rotation, chemical treatments, and using resistant varieties.
In this presentation you will be learning about the SPOTTED WILT VIRUSES which is caused in TOMATO crop. And also its mode of establishment into the crop, deficiency symptoms, life cycle, life span of the virus, yield losses in that particular crop and at last its MANAGEMENT PRACTICES.
Plant viruses are transmitted from plant to plant in a number of ways.
Transmission of viruses by vegetative propagation.
Mechanical transmission of viruses through sap.
Transmission of viruses by seed.
Transmission of viruses by Pollen.
Transmission of viruses by dodder.
Transmission by vectors.
Viral infections in plants can be controlled through several strategies including using certified seed/plants, controlling weeds that harbor viruses, and insecticide use since most viruses are vector-borne. Transgenic virus resistance involves expressing viral genes including coat proteins, replicases, movement proteins, or antisense RNA to interfere with viral replication or movement. The papaya industry was saved through a transgenic papaya resistant to papaya ringspot virus. While virus resistance holds promise, risks like recombination or heterologous encapsidation must be monitored.
1) Plant viruses use various transmission methods like insects, sap, seed, or nematodes to spread between plants since plants cannot move.
2) Plants have two main antiviral resistance mechanisms: R gene-mediated responses and RNA silencing. R genes confer resistance to specific viruses and trigger cell death and systemic resistance. RNA silencing uses small RNAs to degrade or inhibit viral RNA.
3) These mechanisms sometimes overlap when a viral protein can suppress RNA silencing and also be detected by an R gene product as an Avr protein. This indicates communication between the plant's antiviral defense pathways.
This document discusses various methods of plant virus transmission including mechanical, grafting, seed, insect, nematode, and fungal transmission. It provides details on each method such as the viruses transmitted, vectors involved, and procedures. Mechanical transmission involves sap inoculation using leaf rubbing or pinprick methods. Grafting and dodder transmission are also discussed. Seed and pollen transmission of certain viruses is possible. Insect vectors like aphids, whiteflies, and leafhoppers transmit many plant viruses in a circulative or non-persistent manner. Finally, nematodes and fungi can act as vectors for some viruses.
Bhendi yellow vein mosaic virus was first reported by Kulkarni in the year 1924. It was recorded at Bombay and Srilanka simultaneously. This disease is caused by a ss-DNA virus belongs tot the family Geminiviridae and belongs to the genus Begomovirus
Phytoalexins are toxic chemical compounds produced by plants in response to infection by parasites or pathogens. They act as a defense mechanism against invading fungi or bacteria. Hundreds of phytoalexins have been characterized, mostly in the families Fabaceae and Solanaceae. They are produced through the shikimic acid pathway and are often fungistatic rather than fungicidal. Important phytoalexins include pisatin, phaseollin, glyceollin and gossypol. In addition to their role in plant defense, many phytoalexins have potential health benefits for humans such as antioxidant, anti-inflammatory and anticancer properties.
This document discusses plant disease development. It begins by outlining the objectives and topics to be covered, which include the disease triangle, factors for successful disease development, and stages of disease development. The disease triangle requires the presence of a susceptible host, virulent pathogen, and favorable environment. The factors for disease development include the properties of the pathogen, host, and environment. The stages of disease development are inoculation, penetration, infection, growth and reproduction of the pathogen, and dissemination of the pathogen.
This document discusses the Cauliflower Mosaic Virus (CaMV) and its potential use for gene transfer in plants. CaMV is a plant virus that infects brassica plants like cauliflower and turnips. It has a circular double-stranded DNA genome and is spherical in shape. The 35S promoter from CaMV is commonly used in plant transformation due to its strong constitutive expression in dicots. For gene transfer, foreign DNA can be inserted into the non-essential genes II or VII of CaMV. However, CaMV has limitations for gene transfer due to its limited insertion capacity and loss of infectivity if too many nucleotides are added.
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.
Mechanism of disease control by endophytesPooja Bhatt
The document discusses alternative methods for pest management to address problems with chemical pesticides such as development of resistance and environmental contamination. It suggests that biological control using endophytic microorganisms is a promising alternative as endophytes have antagonistic properties against plant pathogens. Endophytes can inhibit pathogens through direct mechanisms such as hyperparasitism, competition, antibiosis, and lytic enzyme production or indirect induction of host plant resistance. Case studies provide examples of endophytes inhibiting fungal plant pathogens through siderophore production, parasitic growth, and antibiotic compounds.
The document summarizes the life cycle of mushrooms. Mushrooms grow in moist, dark places on decaying organic matter. Their life cycle begins as a spore and progresses through five stages, ending when the fruiting body releases new spores. Key stages include the mycelium, basidium, basidiospore, and basidiocarp. Mushrooms are an important source of protein, vitamins, and minerals. Mushroom farming is common in Nepal and produces around 8-10 tons per day, with oyster and white button mushrooms among the edible varieties grown.
This document summarizes the key principles of plant infection:
1) Penetration is the entry of the pathogen into the host, which can occur directly through the plant surface, through wounds, or through natural openings like stomata, hydathodes, or lenticels.
2) Infection is the establishment of the pathogen within the host plant by procuring nutrients from host cells or tissues.
3) Invasion is the spread of the pathogen within the host, which can be intercellular or intracellular depending on the type of pathogen.
4) Dissemination refers to the spread of the pathogen from one plant to another, which can occur autonomously through soil, seeds, or plant parts,
Chemical control of plant diseases involves using chemicals like bactericides, fungicides, and nematicides to inhibit or kill pathogens. Bactericides rely on copper and treat bacterial diseases. Fungicides disrupt fungal cellular processes and are applied as sprays, dusts, or to seeds. Nematicides like aldicarb kill nematodes. Chemicals are applied through soil treatments, seed treatments, or foliar sprays. While effective, chemicals can harm non-target organisms and accumulate up the food chain.
Bacterial soft rot is caused by pectin-degrading bacteria such as Pectobacterium carotovorum, Dickeya dadantii, and certain Pseudomonas species. These bacteria enter plants through wounds and degrade the pectin between plant cells, causing tissues to break down into a soft, watery rot. Soft rot commonly affects potatoes, carrots, tomatoes, and other vegetables. It starts as water-soaked lesions that enlarge and become soft, mushy, and foul-smelling. Good sanitation and avoiding excess moisture can help manage soft rot by limiting bacterial spread and growth.
Virus infection involves several steps: virus entry into the host cell, uncoating of the viral genome, targeting of viral genes to host cell machinery, genome replication, assembly of new viral components, and release of progeny virus. Key proteins like movement proteins and coat proteins facilitate various stages of the infection process by transporting the viral genome and protecting it. The virus life cycle is dependent on hijacking host cell processes and resources for its replication and spread to new cells.
The document summarizes plant defense mechanisms against pathogens. It discusses both structural and biochemical defenses. For structural defenses, it describes preexisting structures like cuticular wax, thick cuticles, and lignified cell walls that physically block pathogens. It also discusses defense structures that develop after infection, like cell wall thickening, callose deposition, and tissue necrosis. For biochemical defenses, it outlines preexisting inhibitors and lack of nutrients for pathogens. It also describes phytoalexins and other compounds produced after infection, such as phenolic compounds and substances that deactivate pathogen enzymes and toxins. The document provides several examples to illustrate different defense strategies in plants.
Plants have developed structural, chemical, and protein-based defenses against pathogens. Structural defenses include waxy coatings, thick cell walls, and pores designed to limit pathogen entry. Chemical defenses include pre-existing compounds like phenolics and induced responses like phytoalexins and hypersensitive response that are activated post-infection. Together, a plant's layered defenses work to detect, stop, and limit damage from invading pathogens.
This document discusses the defense mechanisms of plants against plant pathogens. It describes two main types of defense mechanisms: structural (morphological) defenses and biochemical defenses. Structural defenses include pre-existing barriers like wax layers and thick cell walls, as well as induced defenses created after infection like cork layers and tyloses formation. Biochemical defenses include both pre-existing compounds like phenolics and induced responses like phytoalexin and PR protein production. The document provides examples of specific defense mechanisms employed by plants in response to various pathogens.
a detailed description of structural and biochemical mechanisms and importance of phytoalexins in plants and different types of phytoalexins produced the plants and its functions and importance in plant defense mechanism
Detailed description on the mode of actions of various phytoalexins, mechanisms involved phtyoalexin formation, various types of phytoalexins, its functions
Plants have both pre-existing and induced defense mechanisms against pathogens. Pre-existing defenses include structural barriers like the cuticle, cell walls, and natural openings. Biochemical pre-existing defenses include a lack of recognition factors for pathogens and an absence of receptors for pathogen toxins. When a plant is challenged by a pathogen, it induces additional structural defenses like cork layers and gum deposition. Induced biochemical defenses include the hypersensitive response, which causes cell death around the infection site, production of antimicrobial compounds, and detoxification of pathogen toxins. Both pre-existing and induced defenses help plants resist pathogen infection and disease development.
Defense Mechanism & Pollination pattern in plants pptSUNILKUMARSAHOO16
This document provides an overview of defense mechanisms in plants and patterns of pollination. It discusses structural, chemical, and protein-based defenses plants use against pathogens like fungi, bacteria, and viruses. It also outlines different pollination types including abiotic (wind, water), biotic (insects, birds, bats), and artificial pollination used in hybridization. The document contains detailed information on specific defense structures, chemicals, and the characteristics of different pollination methods. It aims to explain the complex interactions between plants and pathogens or pollinators.
Plants have two main ways to defend themselves against pathogens: structural characteristics and biochemical characteristics. Structural defenses include waxy cuticles, thick cell walls, stomata shape and distribution, trichomes, lenticels, hydathodes, cork layers, abscission layers, and tyloses. Biochemical defenses include the hypersensitive response where infected cells are killed to contain the pathogen, and inducible chemical defenses where pathogens are recognized by molecular patterns which triggers immune responses. Together these structural and biochemical defenses help plants survive attacks from hundreds of potential pathogens.
How plants defend themselves against pathogensMohamed Barakat
Plants have two main ways to defend themselves against pathogens: structural characteristics and biochemical characteristics. Structural defenses include waxy cuticles, thick cell walls, stomata shape and distribution, trichomes, lenticels, hydathodes, cork layers, abscission layers, and tyloses. Biochemical defenses include the hypersensitive response where infected cells are killed to contain the pathogen, and inducible chemical defenses where pathogens are recognized by molecular patterns which triggers immune responses. Together these structural and biochemical defenses help plants survive attacks from hundreds of potential pathogens.
Defence mechanism in plants: Preformed substances and structures.DR. AMIR KHAN
This document discusses various types of plant disease resistance. It begins by defining resistance and describing non-host resistance and gene for resistance. It then discusses true resistance, which is genetically controlled, and divides it into horizontal and vertical resistance. Horizontal resistance is polygenic while vertical is monogenic. Apparent resistance is also discussed, relating to disease escape or tolerance. The document then examines preexisting and induced structural and chemical defenses in plants, providing examples for mechanisms like waxes, cell wall thickening, and pathogenesis-related proteins.
Plants have two types of defense mechanisms against pathogens: structural barriers and biochemical reactions. Structural barriers include pre-existing features like thick cell walls and wax coatings, as well as post-infection responses like cork layers, tyloses, and necrotic tissue that isolate the pathogen. Biochemical defenses include pre-existing inhibitors exuded by the plant and induced responses like the hypersensitive response where infected cells undergo rapid cell death to prevent pathogen spread. Together these mechanisms inhibit pathogens from entering plants, limit their growth and movement within plants, and produce toxic compounds to kill pathogens.
Diseases resistance and defence mechanismsRAMALINGAM K
This document summarizes plant resistance to pathogens and the mechanisms involved. It discusses two main types of resistance - horizontal (polygenic) and vertical (monogenic). It also describes various pre-existing and induced structural defenses plants employ, such as waxes, thickened cell walls, and formation of cork layers. Biochemical defenses include inhibitors, phenolics, phytoalexins, pathogenesis-related proteins, and systemic acquired resistance mediated by salicylic acid. Overall, the document provides an overview of genetic and physiological factors that determine a plant's ability to resist pathogens.
Plants have developed various defense mechanisms to protect themselves from pathogens. Structural defenses include pre-existing structures like thick cuticles, waxes and presence of thick-walled cells. Post-infection, plants induce defenses like formation of cork layers and tyloses to restrict pathogen movement. Biochemical defenses include pre-formed inhibitors and phenolic compounds. After infection, plants produce phytoalexins and hydrolytic enzymes that are pathogenic to invading microbes. Overall, plants utilize an array of physical, chemical and protein-based defenses to detect pathogens and limit infection damage.
Morphological Resistance of Plants against plant pathogens.pptxmanohargowdabp
This document discusses morphological resistance mechanisms in plants against pathogens. It describes that plants defend themselves through structural characteristics and biochemical reactions. Structural defenses include pre-existing features like wax, cuticles, thick cell walls, and stomata shape. Post-infection structural defenses are induced, like cork layer formation, abscission layers, tyloses, and gum deposition that contain or isolate the pathogen. Cell wall defenses also morph to trap pathogens through swelling, thickening, or papillae formation. Overall, plants employ a variety of physical and induced structural changes to resist pathogen penetration and growth.
Plants have several defense mechanisms against pathogens. These include morphological barriers like waxes and hairs that prevent infection. Physiological defenses include preformed chemicals like phenols and induced responses like phytoalexins and lignin production. Genetic defenses can involve single genes for resistance but are often polygenic. Together these morphological, physiological and genetic defenses help plants resist or tolerate infection from pathogens.
1. Plants have various structural defence mechanisms to prevent pathogen infection, including waxes, cuticles, thickened cell walls, and natural openings that limit pathogen entry.
2. After infection occurs, plants form additional defensive structures like cork layers, tyloses, gum deposits, and abscission layers that isolate the pathogen from healthy tissue.
3. Structures like tyloses and sheath formations around hyphae can physically block pathogen spread within the plant. Together, pre-existing and infection-induced structures help plants resist pathogens.
The document discusses the defence mechanisms in plants against pathogens. It describes both structural and biochemical defences. Structural defences provide physical barriers like cuticles, cell walls and induced structures. Biochemical defences include pre-existing compounds like phenols, enzymes and toxins. Post-infection, plants produce phytoalexins, hypersensitivity response and new proteins to inhibit pathogens. The defences have evolved through co-evolution with pathogens and help plants survive attacks.
structuralbarriers for defence-191001065252.pdfdawitg2
This document discusses structural defense mechanisms in plants against pathogens. It describes both constitutive and induced defenses, which can be morphological (structural) or biochemical. Structural defenses include pre-existing barriers like waxy coatings, hairs, lignin and cuticles, as well as sub-surface barriers like epidermal cells, stomata and lenticels. Post-infection defenses form after pathogen attack, such as tyloses that block vascular systems, cork layers that limit lesion size, and hypersensitive response that causes rapid cell death around the infection site. These structural defenses help protect plants by physically blocking pathogens or limiting their spread and access to nutrients.
How to Setup Warehouse & Location in Odoo 17 InventoryCeline George
In this slide, we'll explore how to set up warehouses and locations in Odoo 17 Inventory. This will help us manage our stock effectively, track inventory levels, and streamline warehouse operations.
A workshop hosted by the South African Journal of Science aimed at postgraduate students and early career researchers with little or no experience in writing and publishing journal articles.
The simplified electron and muon model, Oscillating Spacetime: The Foundation...RitikBhardwaj56
Discover the Simplified Electron and Muon Model: A New Wave-Based Approach to Understanding Particles delves into a groundbreaking theory that presents electrons and muons as rotating soliton waves within oscillating spacetime. Geared towards students, researchers, and science buffs, this book breaks down complex ideas into simple explanations. It covers topics such as electron waves, temporal dynamics, and the implications of this model on particle physics. With clear illustrations and easy-to-follow explanations, readers will gain a new outlook on the universe's fundamental nature.
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
Exploiting Artificial Intelligence for Empowering Researchers and Faculty, In...Dr. Vinod Kumar Kanvaria
Exploiting Artificial Intelligence for Empowering Researchers and Faculty,
International FDP on Fundamentals of Research in Social Sciences
at Integral University, Lucknow, 06.06.2024
By Dr. Vinod Kumar Kanvaria
Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
This slide is special for master students (MIBS & MIFB) in UUM. Also useful for readers who are interested in the topic of contemporary Islamic banking.
What is Digital Literacy? A guest blog from Andy McLaughlin, University of Ab...
DefenseMechanisminPlants.pptx
1. DEFENSE MECHANISM IN PLANTS AGAINST PATHOGEN
(STRUCTURAL & BIOCHEMICAL)
DEFENSE MECHANISM IN PLANTS AGAINST
PATHOGENs
(STRUCTURAL & BIOCHEMICAL)
2. INTRODUCTION
Plants represent a rich source of nutrients for many organisms including
fungi, bacteria, virus, nematodes, insects, and vertebrates.
Plant lacking an immune system comparable to animals.
Plants have developed a stunning array of structural, chemical, and protein-
based defenses designed to detect invading organisms and stop them before
they are able to cause extensive damage.
3. Each plant species is affected by approximately 100 different kinds of fungi,
bacteria, mollicutes, viruses and nematodes.
4. HOST:- A living organism from which other organism derive its food.
PATHOGEN:- Any agent (living organism or virus) which can cause
disease.
RESISTANCE:-The ability of an organism to exclude or overcome
completely or in some degree, the effect of a pathogens, or other
damaging factor.
6. STRUCTURAL DEFENSE MECHANISM
The surface of the plant or host is first line of defense against the pathogen.
The pathogen must adhere to the surface and penetrate, if it is to cause
infection.
Structural defense mechanism are mainly two type:-
1. Pre-existing structural defense mechanism
2. Post-infectional or induced structural defense mechanism
7. Pre-existing structural defense
Wax
Thick cuticle
Thickness and toughness of the outer wall of epidermal cells
Stomata
Sclerenchyma cells
Lenticel
Induced structural defense
Cellular defense structure
Hyphal sheathing
Histological defense structure
Formation of cork layer
Formation of abscission layer
Formation of tyloses
Deposition of gums
8. 1-PRE-EXISTING STRUCTURAL DEFENSE
It includes:
Amount and quality of wax and cuticle.
Shapes, size and locations of natural openings (stomata and lenticels).
Presence of thick walled cells in the tissues of the plant that hinder the
advance of pathogen.
Wax-
It is the mixture of long chain
of apolar lipid.
It forming a protective coating
on plant leaves and fruit.
Synthesized by epidermis.
Extremely hydrophobic.
9. Cuticle & Epidermal cell:-
Ex: Disease resistance in Barberry species infected with Puccinia graminis
tritici has been attributed to the tough outer epidermal cells with a thick
cuticle.
In linseed, cuticle acts as a barrier against Melampsora lini.
Silicification and lignifications of epidermal cells offers protection against
Pyricularia oryzae and Streptomyces scabies in paddy and potato,
respectively.
10. Sclerenchyma cells:-
It composed of thickened walls of lignin.
Sclerenchyma cells is present in stem and leaf veins.
Brittle cells help in mechanical support of the plant.
Effectively block the spread of some fungal and bacterial pathogens
that cause angular leaf spot.
Structure of natural opening:-
A. Stomata:-
Most of pathogen enter plants through natural opening.
Some pathogen like stem rust of wheat (Puccinia graminis f.sp. tritici)
can enters its host only when the stomata are open.
Structure of stomata provides resistance to penetration by certain plant
pathogenic bacteria.
11. Ex: Citrus variety, szinkum, is resistant to citrus canker.
12. B. Lenticels :-
Lenticels are openings on fruit, stem and tubers that are filled
with loosely connected cells that allow the passage of air.
Shape and internal structure of lenticels can increase or decrease
the incidence of fruit diseases.
Ex. Small and suberised lenticels will offer resistance to potato
scab pathogen, Streptomyces scabies.
Potato
13. 2. POST-INFECTIONAL/INDUCED STRUCTURAL DEFENSE MECHANISM
Most pathogen manage to penetrate their hosts through wounds
and natural opening and to produce various degree of infection.
Pathogen penetration through the host surface induced the
structural defense mechanism in the host cells.
These may be regarded as:-
Histological defense barriers (cork layer, abscission layers and
tyloses formation)
Cellular defense structures (hyphal sheathing).
14. 1 HISTOLOGICAL DEFENSE STRUCTURES
Cork layer :-
Infection by fungi, bacteria, some viruses and nematodes induce plants
to form several layers of cork cells beyond the point of infection.
These cork cells inhibits the further invasion by the pathogen beyond the
initial lesion and also blocks the spread of toxin substances secreted by
the pathogen.
It also stop the flow of nutrients and water from the healthy to the
infected area and deprive the pathogen of nourishment.
15. Ex- Potato tubers infected by Rhizoctonia
Prunus domestica leaves attacked by Coccomyces pruniphorae.
16. ABSCISSION LAYERS
An abscission layer consists of a gap formed between infected and
healthy cells of leaf surrounding the locus of infection.
Due to the disintegration of middle lamella of parenchymatous
tissue.
Gradually, infected area shrivels, dies, and sloughs off, carrying
with it the pathogen.
Abscission layers are formed on young active leaves of stone
fruits infected by fungi, bacteria or viruses.
18. TYLOSES
Tyloses are the overgrowths of the protoplast of adjacent living
parenchymatous cells, which protrude into xylem vessels through pits.
Tyloses have cellulosic walls.
It formed quickly ahead of the pathogen and may clog the xylem vessels
completely blocking the further advance of the pathogen in resistant
varieties.
19. Ex: Tyloses form in xylem vessels of most plants under invasion by most
of the vascular wilt pathogens.
20. GUM DEPOSITION-
Various types of gums are produced by many plants around lesions after
infection by pathogen or injury.
Gums secretion is most common in stone fruit trees but occurs in most
plants.
Generally these gums are exudated by plant under stressed condition.
Gummosis is the process in which gum produced by the plants and trees.
21. 2 CELLULAR DEFENSE STRUCTURE
Hyphal sheathing:-
Hyphal sheathing is observed in flax infected with Fusarium
oxysporum f.sp. lini.
22. BIOCHEMICAL DEFENSE MECHANISM
Pre-existing chemical defense
1. Inhibitors
Released by plant in it’s environment
Present in plant cells before infection
2. Phenolics
Tannins
Glucanases
Dienes
Chitinase
Induced chemical defense
Hypersensitivity response (HR)
Production of Antimicrobial substances
Phytoalexins
Plantibodies
23. PRE-EXISTING CHEMICAL DEFENSE
Although structural characteristics may provide a plant with various degree
of defense against attacking pathogens.
It is clear that the resistance of a plant against pathogen attack depends not
so much on its structural barriers as on the substances produced in its cell
before or after infection.
Before infection or penetration of pathogens, host released some chemicals
to defend themselves.
24. INHIBITORS RELEASED BY THE PLANT IN IT’S
ENVIRONMENT
Plants exude a variety of substances through the surface of their
aboveground parts as well as through the surface of their roots.
Inhibitory substances directly affect micro-organisms or encourage certain
groups to dominate the environment which may act as antagonists to
pathogens.
Ex 1: Root exudates of marigold contain α-terthinyl which is inhibitory
to nematodes.
Ex 2: In Cicer arietinum (chickpea), the Ascochyta blight resistant
varieties have more glandular hairs which have maleic acid which
inhibit spore germination.
25. Ex 3:Red scales of red onion contain the phenolic compounds,
protocatechuic acid and catechol.
Production of toxic compounds by the rhizoplane / phylloplane or
rhizosphere/phyllosphere micro flora.
26. INHIBITORS PRESENT IN PLANT CELLS BEFORE
INFECTION
It is becoming increasingly apparent that some plants are resistant to
disease caused by certain pathogens of an inhibitory compound present in
the cell before infection.
It stored in vacuoles of plant cells.
Phenolics – onion (catechol and protocatechuic acid ).
Tannins, and some fatty acid-like compound such as dienes,which are
present in high concentrations in cells of young fruits, leaves or seeds.
These compounds are potent inhibitors of many hydrolytic enzymes.
Ex: Chlorogenic acid in potato inhibits common scab bacteria,
Streptomyces scabies,and to wilt pathogen, Verticillium alboatrum
27. Saponins:-
It have antifungal membranolytic activity.
Ex: Tomatine in tomato and Avenacin in oats.
Lactins:-
They are protiens.
Bind specifically to certain sugars and occur in large concentrations in
many types of seeds, cause “lysis” and growth inhibition of many fungi.
Hydrolytic enzymes:-
“Glucanases” and “chitinases” enzymes.
It may cause breakdown of pathogen cellwall.
28. INDUCED CHEMICAL DEFENSE
Phytoalexins:- (Phyton = plant; alexin = to ward off)
Muller and Borger (1940) first used the term phytoalexins for fungistatic
compounds produced by plants in response to injury (mechanical or
chemical) or infection.
Phytoalexens are toxic antimicrobial substances.
It produced in appreciable amounts in plants only after stimulation by
phytopathogenic micro-organisms or by chemical or mechanical injury.
Phytoalexins are not produced during compatable reaction.
29. Characteristics of phytoalexins:-
Fungitoxic and bacteriostatic at low concentrations.
Produced in host plants in response to stimulus (elicitors) and metabolic products.
Absent in healthy plants.
Remain close to the site of infection.
Produced in quantities proportionate to the size of inoculum.
Produced in response to the weak or nonpathogens than pathogens.
Produced within 12-14 hours reaching peak around 24 hours after inoculation.
Host specific rather than pathogen specific.
S.No Phytoalexin Host Pathogen
1 Pisatin Pea Monilinia fructicola
2 Phaseolin French bean Sclerotenia fructigena
3 Rishitin Potato Phytopthora infestans
4 Gossipol Cotton Verticillum alboratum
5 Cicerin Bengal gram Ascochyta blight
6 Ipomeamarone Sweet potato Ceratocystis fimbriata
7 Capsidol Pepper Colletotrichum capsici
30. Hypersensitive response (HR):-
The term hypersensitivity was first used by Stakman (1915) in wheat infected by rust
fungus, Puccinia graminis.
The HR is a localized induced cell death in the host plant at the site of infection by a
pathogen, thus limiting the growth of pathogen.
HR occurs only in incompatible host-pathogen combinations.
HR is initiated by the recognition of specific pathogen-produced signal molecules,
known as elicitors.
31. Plantibodies:-
It is generally antibodies.
It is encoded by animal genes, but produced in and by the plants.
So that it is called as plantibodies.
Transgenic plants have been produced which are genetically engineered to
incorporate into their genome, and to express foreign genes.
Mouse genes that produce antibodies against certain plant pathogens.
It shown in transgenic plant.
Ex:-Artichoke mottled crinkle virus
32. CONCLUSION
Both the host and pathogen evolve in nature side by side.
Disease development depends upon successful host-pathogen interaction.
Susceptibility and resistance of a host against various pathogens is
predominantly decided by the gene.
Different types of chemical and structural defense mechanism provide
plant defenses response to the pathogens.
Defense mechanism will not work ,when compatible reaction occurs
between host and pathogen.