Pathogenesis-related proteins (initially named “b” proteins) were discovered in tobacco leaves
hypersensitively reacting to TMV by two independently working groups (Van Loon and Van Kammen,
1970; Gianinazzi et al., 1970)
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.
This document discusses pathogenesis-related (PR) proteins in plants. It describes 17 families of PR proteins that are toxic to invading pathogens. While present at low levels in healthy plants, PR proteins are produced in much higher amounts when the plant is under pathogen attack or stress. The document outlines the different activities, targets, and functions of several PR protein families, including their roles in inhibiting pathogens through enzymatic activities, strengthening cell walls, or permeabilizing pathogen cell membranes. It concludes that PR proteins play an important role in plant disease resistance and stress response.
Plant disease resistance occurs through both pre-formed structures and infection-induced immune responses. There are two tiers of the plant immune system - pattern-triggered immunity (PTI) triggered by pathogen-associated molecular patterns (PAMPs), and effector-triggered immunity (ETI) triggered by recognition of pathogen effectors through resistance (R) proteins. Quantitative resistance involving multiple genes provides more durable resistance than major gene resistance. Genetic engineering and breeding can enhance crop disease resistance through introduction of R genes or resistance mechanisms.
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.
This document discusses pathogenesis-related (PR) proteins found in plants. It begins with definitions, noting that PR proteins are produced when plants are infected by pathogens and act to decrease susceptibility. It then describes 17 types of PR proteins classified into families based on their properties, with examples like chitinase and glucanase. Mechanisms of action are discussed, such as degrading fungal cell walls. The document concludes by outlining applications for transferring PR protein genes to transgenic plants to engineer resistance against pathogens like fungi and bacteria.
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.
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.
The concept of gene for gene hypothesis was first developed by Flor in 1956 based on his studies of host pathogen interaction in flax, for rust caused by Melampsora lini. The gene for gene hypothesis states that for each gene controlling resistance in the host, there is corresponding gene controlling pathogenicity in the pathogen. The resistance of host is governed by dominant genes and virulence of pathogen by recessive genes. The genotype of host and pathogen determine the disease reaction. When genes in host and pathogen match for all loci, then only the host will show susceptible reaction. If some gene loci remain unmatched, the host will show resistant reaction. Now gene – for –gene relationship has been reported in several other crops like potato, sorghum, wheat, etc. The gene for gene hypothesis is also known as “Flor Hypothesis.”
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.
This document discusses pathogenesis-related (PR) proteins in plants. It describes 17 families of PR proteins that are toxic to invading pathogens. While present at low levels in healthy plants, PR proteins are produced in much higher amounts when the plant is under pathogen attack or stress. The document outlines the different activities, targets, and functions of several PR protein families, including their roles in inhibiting pathogens through enzymatic activities, strengthening cell walls, or permeabilizing pathogen cell membranes. It concludes that PR proteins play an important role in plant disease resistance and stress response.
Plant disease resistance occurs through both pre-formed structures and infection-induced immune responses. There are two tiers of the plant immune system - pattern-triggered immunity (PTI) triggered by pathogen-associated molecular patterns (PAMPs), and effector-triggered immunity (ETI) triggered by recognition of pathogen effectors through resistance (R) proteins. Quantitative resistance involving multiple genes provides more durable resistance than major gene resistance. Genetic engineering and breeding can enhance crop disease resistance through introduction of R genes or resistance mechanisms.
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.
This document discusses pathogenesis-related (PR) proteins found in plants. It begins with definitions, noting that PR proteins are produced when plants are infected by pathogens and act to decrease susceptibility. It then describes 17 types of PR proteins classified into families based on their properties, with examples like chitinase and glucanase. Mechanisms of action are discussed, such as degrading fungal cell walls. The document concludes by outlining applications for transferring PR protein genes to transgenic plants to engineer resistance against pathogens like fungi and bacteria.
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.
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.
The concept of gene for gene hypothesis was first developed by Flor in 1956 based on his studies of host pathogen interaction in flax, for rust caused by Melampsora lini. The gene for gene hypothesis states that for each gene controlling resistance in the host, there is corresponding gene controlling pathogenicity in the pathogen. The resistance of host is governed by dominant genes and virulence of pathogen by recessive genes. The genotype of host and pathogen determine the disease reaction. When genes in host and pathogen match for all loci, then only the host will show susceptible reaction. If some gene loci remain unmatched, the host will show resistant reaction. Now gene – for –gene relationship has been reported in several other crops like potato, sorghum, wheat, etc. The gene for gene hypothesis is also known as “Flor Hypothesis.”
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 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.
plant pathogen interaction
different types of pathogens
gene for gene hypothesis
direct receptor model
Elicitor receptor model
suppersor repressor model
gaurd hypothesis
Hypersensitivity and its Mechanism summarizes the hypersensitive response (HR) in plants. The HR is a localized cell death response at the site of infection that limits pathogen growth and provides resistance. It involves the recognition of pathogen elicitors by plant receptors, which activates a biochemical reaction cascade and the production of reactive oxygen species and defense compounds. This leads to cell death in infected areas and the acquisition of systemic resistance in other plant tissues through signaling molecules like salicylic acid, jasmonic acid, and ethylene. The HR occurs through specific host-pathogen combinations and results in the depolarization of membranes and disintegration of cellular components at the infection site.
Gentic engineering for disease resistance in cropsChainika Gupta
Genetic engineering can be used to develop transgenic disease resistance in crops. First generation strategies introduced single antimicrobial genes, but second generation strategies manipulate entire signaling pathways for more durable resistance. Targets for second generation strategies include modifying defense signaling pathways using hormones, defense modulators like NPR1, transcription factors like WRKY, and R-genes. Other strategies express virulence factor detoxifiers, antimicrobial peptides/metabolites, phytoalexins, viral coat proteins or replicases, and antisense RNA to inhibit various plant pathogens. While promising, developing transgenic resistance also faces challenges like durability and effects on other pathogens.
- Hypersensitivity is a plant defense mechanism characterized by rapid programmed cell death at the site of infection to prevent pathogen spread. It is initiated by the recognition of pathogen elicitors by plant resistance proteins.
- This triggers biochemical responses like reactive oxygen species production and phytoalexin accumulation that cause cell death around the infection site. This localized cell death limits the pathogen to a small area and prevents disease development.
- The hypersensitive response is an example of incompatible interactions between plants with specific resistance genes and pathogens with corresponding avirulence genes. It represents a successful defense strategy employed by plants.
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.
Biotechnological approches in disease managementrahul manjunath
This document discusses various biotechnological approaches for plant disease management, including tissue culture, recombinant DNA technology, and transgenic approaches. Tissue culture techniques like meristem culture can produce disease-free planting materials. Recombinant DNA technology allows generation of resistant plants by expressing genes conferring resistance to bacterial, fungal or viral diseases. Transgenic approaches discussed include pathogen-derived resistance utilizing viral coat protein or movement genes, as well as expressing plant disease resistance genes, ribosome-inactivating proteins, and genes involved in systemic acquired resistance.
The document discusses the role of enzymes, toxins, and growth regulators in plant pathology and disease development. It defines plant pathology and describes how diseases develop through a complex process influenced by environmental factors and stress. The summary is:
1) Plant pathology studies plant diseases and their causes and controls. Disease develops through interactions between pathogens, hosts, and the environment.
2) Key stages of disease development include inoculation, penetration, infection, pathogen growth and reproduction, and dissemination. Disease occurs when conditions are suitable for the pathogen but not the host.
3) Factors like temperature, moisture, light, soil properties, and wind influence disease development by affecting the pathogen, host, or their interaction. Understanding
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
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.
Systemic Acquired Resistance (SAR) and it’s Significance in Plant Disease Ma...Ankit Chaudhari
Systemic Acquired Resistance (SAR) is a mechanism of induced defense that confers long-lasting protection against a broad spectrum of microorganisms and pests. Presently disease control is largely based on the use of hazardous chemicals viz., fungicides, bactericides and insecticides for either direct or indirect disease management. The hazardous natures of the products on the environment, human and animal health strongly necessitates the search for new safer means of disease control. SAR have high potential to diminish the use of toxic chemicals in the agriculture and has emerged as an alternative, non-conventional, non-biocidal and eco-friendly approach for plant protection and hence for sustainable agriculture. SAR requires the signal molecule salicylic acid (SA) and is associated with accumulation of pathogenesis-related proteins, which are thought to contribute to resistance.
This document discusses toxins produced by plant pathogens. It begins by classifying toxins into three categories: pathotoxins, phytotoxins, and vivotoxins. It then discusses specific toxins in more detail, distinguishing between host-specific toxins and non-host specific toxins. Examples of both types of toxins are provided, along with descriptions of their modes of action and effects on host tissues. Overall, the document reviews the role of toxins in plant disease development and pathogenesis.
EFFECT OF PATHOGEN ON HOST PLANT PHYSIOLOGYfarheen khan
Plant pathogens can interfere with key plant physiological functions such as photosynthesis, respiration, transpiration, nutrient transport, and cellular processes. This document discusses how pathogens disrupt these functions through tissue damage, toxin production, and cellular changes. Specifically, it notes that pathogens reduce photosynthesis by destroying chlorophyll or inhibiting related enzymes. They also increase plant respiration and interfere with nutrient transport through the xylem and phloem.
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.
This document discusses different types of plant resistance to pathogens. It describes true resistance, which includes partial/quantitative/polygenic resistance controlled by multiple genes (horizontal resistance) and R-gene/monogenic resistance controlled by single genes (vertical resistance). It also discusses the genetics of virulence in pathogens and resistance in host plants using the gene-for-gene concept. Specifically, it explains how avirulence genes in pathogens interact with resistance genes in plants to determine compatibility.
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
Transgenic strategies for improving rice disease resistanceKiranKumarN24
This document discusses strategies for developing transgenic rice with resistance to diseases. It begins by noting the importance of rice as a staple food and the many diseases that affect rice production. Transgenic approaches are proposed as a way to develop durable disease resistance through genetic engineering. Different strategies for engineering resistance to viruses, bacteria, and fungi are described, including expressing coat proteins, replication enzymes, RNA interference, and defense-related genes. Transformation techniques like Agrobacterium-mediated transfer are also outlined. The document concludes by acknowledging both the promise and limitations of transgenic disease resistance in rice.
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 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.
plant pathogen interaction
different types of pathogens
gene for gene hypothesis
direct receptor model
Elicitor receptor model
suppersor repressor model
gaurd hypothesis
Hypersensitivity and its Mechanism summarizes the hypersensitive response (HR) in plants. The HR is a localized cell death response at the site of infection that limits pathogen growth and provides resistance. It involves the recognition of pathogen elicitors by plant receptors, which activates a biochemical reaction cascade and the production of reactive oxygen species and defense compounds. This leads to cell death in infected areas and the acquisition of systemic resistance in other plant tissues through signaling molecules like salicylic acid, jasmonic acid, and ethylene. The HR occurs through specific host-pathogen combinations and results in the depolarization of membranes and disintegration of cellular components at the infection site.
Gentic engineering for disease resistance in cropsChainika Gupta
Genetic engineering can be used to develop transgenic disease resistance in crops. First generation strategies introduced single antimicrobial genes, but second generation strategies manipulate entire signaling pathways for more durable resistance. Targets for second generation strategies include modifying defense signaling pathways using hormones, defense modulators like NPR1, transcription factors like WRKY, and R-genes. Other strategies express virulence factor detoxifiers, antimicrobial peptides/metabolites, phytoalexins, viral coat proteins or replicases, and antisense RNA to inhibit various plant pathogens. While promising, developing transgenic resistance also faces challenges like durability and effects on other pathogens.
- Hypersensitivity is a plant defense mechanism characterized by rapid programmed cell death at the site of infection to prevent pathogen spread. It is initiated by the recognition of pathogen elicitors by plant resistance proteins.
- This triggers biochemical responses like reactive oxygen species production and phytoalexin accumulation that cause cell death around the infection site. This localized cell death limits the pathogen to a small area and prevents disease development.
- The hypersensitive response is an example of incompatible interactions between plants with specific resistance genes and pathogens with corresponding avirulence genes. It represents a successful defense strategy employed by plants.
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.
Biotechnological approches in disease managementrahul manjunath
This document discusses various biotechnological approaches for plant disease management, including tissue culture, recombinant DNA technology, and transgenic approaches. Tissue culture techniques like meristem culture can produce disease-free planting materials. Recombinant DNA technology allows generation of resistant plants by expressing genes conferring resistance to bacterial, fungal or viral diseases. Transgenic approaches discussed include pathogen-derived resistance utilizing viral coat protein or movement genes, as well as expressing plant disease resistance genes, ribosome-inactivating proteins, and genes involved in systemic acquired resistance.
The document discusses the role of enzymes, toxins, and growth regulators in plant pathology and disease development. It defines plant pathology and describes how diseases develop through a complex process influenced by environmental factors and stress. The summary is:
1) Plant pathology studies plant diseases and their causes and controls. Disease develops through interactions between pathogens, hosts, and the environment.
2) Key stages of disease development include inoculation, penetration, infection, pathogen growth and reproduction, and dissemination. Disease occurs when conditions are suitable for the pathogen but not the host.
3) Factors like temperature, moisture, light, soil properties, and wind influence disease development by affecting the pathogen, host, or their interaction. Understanding
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
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.
Systemic Acquired Resistance (SAR) and it’s Significance in Plant Disease Ma...Ankit Chaudhari
Systemic Acquired Resistance (SAR) is a mechanism of induced defense that confers long-lasting protection against a broad spectrum of microorganisms and pests. Presently disease control is largely based on the use of hazardous chemicals viz., fungicides, bactericides and insecticides for either direct or indirect disease management. The hazardous natures of the products on the environment, human and animal health strongly necessitates the search for new safer means of disease control. SAR have high potential to diminish the use of toxic chemicals in the agriculture and has emerged as an alternative, non-conventional, non-biocidal and eco-friendly approach for plant protection and hence for sustainable agriculture. SAR requires the signal molecule salicylic acid (SA) and is associated with accumulation of pathogenesis-related proteins, which are thought to contribute to resistance.
This document discusses toxins produced by plant pathogens. It begins by classifying toxins into three categories: pathotoxins, phytotoxins, and vivotoxins. It then discusses specific toxins in more detail, distinguishing between host-specific toxins and non-host specific toxins. Examples of both types of toxins are provided, along with descriptions of their modes of action and effects on host tissues. Overall, the document reviews the role of toxins in plant disease development and pathogenesis.
EFFECT OF PATHOGEN ON HOST PLANT PHYSIOLOGYfarheen khan
Plant pathogens can interfere with key plant physiological functions such as photosynthesis, respiration, transpiration, nutrient transport, and cellular processes. This document discusses how pathogens disrupt these functions through tissue damage, toxin production, and cellular changes. Specifically, it notes that pathogens reduce photosynthesis by destroying chlorophyll or inhibiting related enzymes. They also increase plant respiration and interfere with nutrient transport through the xylem and phloem.
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.
This document discusses different types of plant resistance to pathogens. It describes true resistance, which includes partial/quantitative/polygenic resistance controlled by multiple genes (horizontal resistance) and R-gene/monogenic resistance controlled by single genes (vertical resistance). It also discusses the genetics of virulence in pathogens and resistance in host plants using the gene-for-gene concept. Specifically, it explains how avirulence genes in pathogens interact with resistance genes in plants to determine compatibility.
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
Transgenic strategies for improving rice disease resistanceKiranKumarN24
This document discusses strategies for developing transgenic rice with resistance to diseases. It begins by noting the importance of rice as a staple food and the many diseases that affect rice production. Transgenic approaches are proposed as a way to develop durable disease resistance through genetic engineering. Different strategies for engineering resistance to viruses, bacteria, and fungi are described, including expressing coat proteins, replication enzymes, RNA interference, and defense-related genes. Transformation techniques like Agrobacterium-mediated transfer are also outlined. The document concludes by acknowledging both the promise and limitations of transgenic disease resistance in rice.
PR proteins in plant disease resistance.pptxReddykumarAv
Pathogenesis-related (PR) proteins are proteins produced in plants in the event of a pathogen attack.[1] They are induced as part of systemic acquired resistance. Infections activate genes that produce PR proteins. Some of these proteins are antimicrobial, attacking molecules in the cell wall of a bacterium or fungus. Others may function as signals that spread “news” of the infection to nearby cells. Infections also stimulate the cross-linking of molecules in the cell wall and the deposition of lignin, responses that set up a local barricade that slows spread of the pathogen to other parts of the plant
application of plant transformation for productivity and performanceAshika Raveendran
This document discusses pathogenesis-related (PR) proteins in plants. It notes that plants produce PR proteins when under pathogen attack, like from fungi. There are over 14 families of PR proteins with different functions, such as having antifungal, glucanase, or chitinase activity. The document outlines several specific PR proteins (PR-1 through PR-5), describing their molecular weights, presence in various plant species, and antifungal mechanisms. It also mentions several other types of antifungal proteins found in plants.
- Systemic Acquired Resistance (SAR) is a plant defense mechanism that confers long-lasting protection against a broad spectrum of pathogens. It involves the accumulation of pathogenesis-related (PR) proteins in response to salicylic acid (SA) signaling.
- SAR is triggered by initial infection at a local site and protects the entire plant. It provides an alternative to toxic chemicals for controlling plant diseases in a sustainable way.
- Key events in SAR include the production of SA at the infection site, transmission of the SAR signal systemically, and accumulation of PR proteins that contribute to broad-spectrum resistance against future infections.
Defence Mechanism In Plants Against Fungal PathogenPrashant Gigaulia
This document summarizes the defense mechanisms plants use against fungal pathogens. It discusses how plants detect pathogens via pattern recognition receptors that recognize pathogen-associated molecular patterns. This triggers signal transduction pathways that activate defense responses like producing antimicrobial compounds, cell wall modifications, and programmed cell death around infection sites. It also describes the phases of plant immunity: PAMP-triggered immunity, effector-triggered susceptibility when pathogens suppress PTI, and effector-triggered immunity when plants recognize effector proteins via resistance genes. The document provides details on several defense responses like hypersensitive response, systemic acquired resistance, and phytoalexin production.
This document summarizes research on cloning and expression analysis of rice genes involved in infection with the rice nematode Hirschmaniella oryzae. Key points include:
- Six rice genes were selected based on previous expression data under H. oryzae infection. These genes were cloned from rice roots.
- An infection experiment was conducted where rice seedlings were infected with nematodes at different time points. Gene expression was analyzed using qPCR.
- Preliminary results found three genes - Cupin, Membrane, and B-box - had expression patterns consistent with previous data under H. oryzae infection. Further research is suggested to understand the roles of these genes in rice-
This document summarizes the history and applications of RNA interference (RNAi) and microRNAs (miRNAs) in plants. It discusses how small RNAs guide regulatory processes, how dicer and argonauts are involved, and some of the early discoveries in RNAi from the 1990s onward. It then lists several applications of RNAi/miRNAs in plants, such as improving traits like biomass, yield, stress resistance, and nutrition. Specific examples are given of overexpressing miRNAs like miR156 to increase biomass and yield in maize and rice. In conclusion, RNAi/miRNAs can be powerful tools for improving important agricultural traits in plants.
Defensins: Antimicrobial peptide for the host plant resistancesnehaljikamade
Since the beginning of the 90s lots of cationic plant, cysteine-rich antimicrobial peptides (AMP) have been studied. However, Broekaert et al. (1995) only coined the term “plant defensin,” after comparison of a new class of plant antifungal peptides with known insect defensins. From there, many plant defensins have been reported and studies on this class of peptides encompass its activity toward microorganisms and molecular features of the mechanism of action against bacteria and fungi. Plant defensins also have been tested as biotechnological tools to improve crop production through fungi resistance generation in organisms genetically modified (OGM). Its low effective concentration towards fungi, ranging from 0.1 to 10 μM and its safety to mammals and birds makes them a better choice, in place of chemicals, to control fungi infection on crop fields. Herein, is a review of the history of plant defensins since their discovery at the beginning of 90s, following the advances on its structure conformation and mechanism of action towards microorganisms is reported. This review also points out some important topics, including: (i) the most studied plant defensins and their fungal targets; (ii) the molecular features of plant defensins and their relation with antifungal activity; (iii) the possibility of using plant defensin(s) genes to generate fungi resistant GM crops and biofungicides; and (iv) a brief discussion about the absence of products in the market containing plant antifungal defensins.
This research article describes a genome-wide analysis of histone modifications (H3K9me2 and H4K12ac) and gene expression in common bean (Phaseolus vulgaris L.) leaves inoculated with the fungal pathogen Uromyces appendiculatus, which causes bean rust disease. ChIP-Seq was used to identify differentially methylated and acetylated regions between inoculated and mock-inoculated leaves at 0, 12 and 84 hours after inoculation. RNA-Seq was used to identify differentially expressed genes. Key defense genes and transcription factors involved in the bean-rust interaction were identified. The study provides insights into epigenomic regulation of gene expression during biotic stress in common
Biochemical basis for resistance to plant pathogensMamoonRasheed7
The document summarizes different types of plant defense mechanisms against pathogens, including passive defenses like waxy cuticles and cell wall appositions, as well as active defenses like phytoalexins, PR proteins, protein synthesis inhibitors, and tannins and melanins. It describes several examples of these defenses such as phytoalexins including isoflavonoids and stilbenes, and the roles of PR proteins like β-1,3-glucanases and chitinases in weakening fungal cell walls. The document concludes that understanding these defense mechanisms provides insights into plant adaptation and development, while further study of their gene regulation could aid crop improvement.
Deployment of broad spectrum resistance against rice blast which includes gene pyramiding, deployment, transgenic approaches, marker assisted back cross breeding, pedigree by using major R genes and QTLs and phytoalexin genes.
Biotechnology and disease management with special reference toSarda Konjengbam
Plant biotechnology can be defined as the use of tissue culture and genetic engineering techniques to produce genetically modified plants that exhibit new or improved desirable characteristics.
PLANT BIOTECHNOLOGY HELPS PLANT PATHOLOGY IN MANY WAYS.
This document summarizes the potential of RNA interference (RNAi) technology for crop improvement. It discusses how RNAi was discovered through early experiments in plants in the 1990s. The mechanism of RNAi involves long double-stranded RNA being cleaved by an enzyme called Dicer into small interfering RNAs (siRNAs) that are incorporated into a protein complex called RISC that targets and degrades complementary mRNAs, preventing gene expression. The document outlines several successful applications of RNAi technology for increasing biotic stress tolerance in crops against viruses, bacteria, fungi and insects by silencing key pathogen genes. It also discusses using RNAi to modify other crop traits like nutritional quality and abiotic stress resistance.
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.
This document reviews the current status of natural virus resistance genes and prospects for deploying these genes against virus infections. It discusses dominant resistance genes that confer monogenic resistance through recognition of viral avirulence factors. To date, 12 examples have been characterized that fall into the nucleotide binding site-leucine rich repeat class. Recessive resistance genes that cause impaired susceptibility by disrupting host factors required for virus infection are also described. These include mutations in translation initiation factors that cause resistance to various potyviruses and other viruses. Advances in genomics and molecular techniques are improving prospects for identifying and utilizing natural virus resistance genes in crop breeding programs.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
Remote Sensing and Computational, Evolutionary, Supercomputing, and Intellige...University of Maribor
Slides from talk:
Aleš Zamuda: Remote Sensing and Computational, Evolutionary, Supercomputing, and Intelligent Systems.
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Inter-Society Networking Panel GRSS/MTT-S/CIS Panel Session: Promoting Connection and Cooperation
https://www.etran.rs/2024/en/home-english/
BREEDING METHODS FOR DISEASE RESISTANCE.pptxRASHMI M G
Plant breeding for disease resistance is a strategy to reduce crop losses caused by disease. Plants have an innate immune system that allows them to recognize pathogens and provide resistance. However, breeding for long-lasting resistance often involves combining multiple resistance genes
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
ANAMOLOUS SECONDARY GROWTH IN DICOT ROOTS.pptxRASHMI M G
Abnormal or anomalous secondary growth in plants. It defines secondary growth as an increase in plant girth due to vascular cambium or cork cambium. Anomalous secondary growth does not follow the normal pattern of a single vascular cambium producing xylem internally and phloem externally.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
Nucleophilic Addition of carbonyl compounds.pptxSSR02
Nucleophilic addition is the most important reaction of carbonyls. Not just aldehydes and ketones, but also carboxylic acid derivatives in general.
Carbonyls undergo addition reactions with a large range of nucleophiles.
Comparing the relative basicity of the nucleophile and the product is extremely helpful in determining how reversible the addition reaction is. Reactions with Grignards and hydrides are irreversible. Reactions with weak bases like halides and carboxylates generally don’t happen.
Electronic effects (inductive effects, electron donation) have a large impact on reactivity.
Large groups adjacent to the carbonyl will slow the rate of reaction.
Neutral nucleophiles can also add to carbonyls, although their additions are generally slower and more reversible. Acid catalysis is sometimes employed to increase the rate of addition.
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
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
The use of Nauplii and metanauplii artemia in aquaculture (brine shrimp).pptxMAGOTI ERNEST
Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
3D Hybrid PIC simulation of the plasma expansion (ISSS-14)
PR Pathogenesis related proteins
1. Department of Mycology and Plant Pathology
Institute of Agricultural Sciences
Banaras Hindu University
Presented by:
Mamoon Rasheed
M.Sc. (Ag.) Prev
2. • Pathogenesis-related proteins (initially named “b” proteins) were discovered in tobacco leaves
hypersensitively reacting to TMV by two independently working groups (Van Loon and Van Kammen,
1970; Gianinazzi et al., 1970)
• Assumption : These proteins are commonly induced in resistant plants, expressing a hypersensitive
necrotic response (HR) to pathogens of viral, fungal and bacterial origin.
• Later, however, it turned out that b-proteins are induced not only in resistant, but also in susceptible
plant – pathogen interactions, as well as in plants, subjected to abiotic stress factors (Van Loon, 1985)
• 1980 Antoniw et al. coined the term “pathogenesis-related proteins” (PRs), which have been defined
as “proteins encoded by the host plant but induced only in pathological or related situations”, the
latter implying situations of non-pathogenic origin.
Where it all started
Source : Edreva, A. (2005). Pathogenesis-related proteins: research progress in the last 15 years. Gen Appl Plant
Physiol, 31(1-2), 105-24.
3. • Originally, five main groups of PRs (PR-1 to PR-5) - numbered in order of decreasing
electrophoretic mobility. Each group consists of several members with similar properties
(Bol et al., 1990)
• Criteria used for the inclusion of new families into PRs are that
(a)The protein must be induced by a pathogen in tissues that do not normally express it
(b)Induced expression must occur in at least two different plant-pathogen
combinations, or expression in a single plant-pathogen combination must be confirmed
independently in different laboratories (Van Loon and Van Strien, 1999)
Classification
Citation : Edreva, A. (2005). Pathogenesis-related proteins: research progress in the last 15 years. Gen Appl Plant
Physiol, 31(1-2), 105-24.
4. Text
Head
Citation : Van Loon, L. C., & Van Strien, E. A. (1999). The families of pathogenesis-related proteins, their activities, and comparative
analysis of PR-1 type proteins. Physiological and molecular plant pathology, 55(2), 85-97.
5. Head
Citation : van Loon, L. C., Rep, M., & Pieterse, C. M. (2006). Significance of inducible defense-related proteins in infected plants. Annu. Rev.
Phytopathol., 44, 135-162.
6. • They are low-molecular proteins (6-43 kDa), extractable and stable at low pH (< 3),
thermostable, and highly resistant to proteases (Van Loon, 1999).
• Apart from being present in the primary and secondary cell walls of infected plants,
PRs are also found in cell wall appositions (papillae) deposited at the inner side of
cell wall in response to fungal attack (Benhamou et al., 1991; Jeun, 2000).
• PRs are established in all plant organs – leaves, stems, roots, flowers (Van Loon,
1999), being particularly abundant in the leaves, where they can amount to 5-10% of
total leaf proteins.
Biochemical and structural character
7. • The four α-helices I to IV are shown red and yellow, the
four β-strands A to D cyan arranged antiparallel
between helices, other polypeptide segments gray, and
the polypeptide chain ends are indicated with N and C.
• The tight packing of the α-helices on both sides of the
central β-sheet (α−β−α sandwich structure) results in a
compact, bipartite molecular core, which is stabilized
by hydrophobic interactions and multiple hydrogen
bonds
Biochemical and structural character
Citation : Fernández, C., Szyperski, T., Bruyere, T., Ramage, P., Mösinger, E., & Wüthrich, K. (1997). NMR solution
structure of the pathogenesis-related protein P14a. Journal of molecular biology, 266(3), 576-593.
The structure of a PR-1 family member (tomato PR1-b) was
solved by nuclear magnetic resonance
8. • Shows β-1,3-glucanase activity
• M.W. of β -1,3-Gs 33 to 44 kDa
• In Nicotiana species:
• Class I: PR2e subgroup, these are basic protein localized in cell vacuole
• Class II: PR2a ,PR2b and PR2c subgroup, these are acidic protein
• Class III: include - PR2d subgroup it is also acidic protein but differs in sequence by at
least 43% from class I and class II
PR2
9. PR2 Mode of action
β-1,3-glucanases are involves in hydrolytic cleavage of the 1,3-β-D-glucosidic linkages in β- 1,3-
glucans, a major componant of fungi cell wall. So that cell lysis and cell death occur as a result
of hydrolysis of glucans present in the cell wall of fungi.
10. • Shows Chitinase activity
• Chitinases are endo β-1,4-glucosaminidases which hydrolyze the β-glycosidic
bond at the reducing end of lucosaminidinides found in chitin, chitosan or
peptidoglycan (Neuhaus,1999)
• Most of Chitinase having molecular mass in the range of 15 kDa and 43 kDa
• Chitinase can be isolated from Chickpea, Cucumber, barley
PR3
11. • Cleaves the cell wall chitin polymers , resulting in a weakened cell wall and
rendering fungal cells osmotically sensitive
• These Chitinases have Significant antifungal activities against plant
pathogenic fungi like
• Alternaria sp.
• Bipolaris oryzae for brown spot of rice
PR3 Mode of action
Citation : Nejad, M. S., Bonjar, G. H. S., & Dehkaei, F. P. (2014). Control of Bipolaris oryzae the causal agent of rice
brown spot disease via soil Streptomyces sp. isolate G. International Journal of Advanced Biological and Biomedical
Research, New Delhi, 2, 310-317.
12. • The possible role of protease inhibitors (PIs) in plant protection was
investigated as early as 1947 by, Mickel and Standish.
• Highly stable defensive proteins that are developmentally regulated and
induced only in response to insect and pathogen attack
• The proteinase inhibitors are classified into
• Serine proteinase inhibitors
• Cysteine proteinase inhibitors
• Aspartate/metallo proteinase inhibitor
PR6
13. • Exhibit a very broad spectrum of activity including suppression of pathogenic
nematodes like Globodera tabaccum, G. pallida, and Meloidogyne incognita
(Williamson and Hussey, 1996)
• Based on the active amino acid in their “reaction center” (Koiwa et al. 1997),
are classified as serine, cysteine, aspartic and metallo-proteases
PR6 Mode of action
14. • “Plant defensin” was coined in 1995 by Terras
• Plant defensins are small (M.W. 5kDa), basic, cysteine-rich
antifungal peptides ranging from 45 to 54 amino acids,
and are positively charged
• Isolated from wheat and barley and were initially
classified as a subgroup of the thionin family called the γ-
thionins
PR12
15. • In bacteria, permeabilization coincided with the inhibition of RNA, DNA and
protein synthesis and decreased bacterial viability
• Antifungal defensins reduce hyphal elongation and induce hyperbranching
PR12 Mode of action
16. PR12 Mode of action
https://www.macmillanhighered.com/BrainHoney/Resource/6716/digital_first_content/trunk/test/hillis2e/hillis2e_ch28_2.html
17. • Recent report shows that SA-dependent expression of PR-1, PR-2, and PR-5 is required for
increased protection against the biotrophic fungus Peronospora parasitica in Arabidopsis,
whereas SA-independent but JA-dependent induction of PR-3 and PR-4 is associated with
the induced resistance against the necrotrophic fungi A. brassicicola (Penninckx et al.
1996)
• SA induces acidic PR genes that are normally activated during SAR, whereas ethylene and
jasmonates are known to induce proteinase inhibitors, defensin, thionin, and basic PR
proteins (Epple et al. 1995; Donnell, et al. 1996; Penninckx et al. 1996)
Role of PR in SAR ISR
Citation : Jain D., Khurana J.P. (2018) Role of Pathogenesis-Related (PR) Proteins in Plant Defense Mechanism. In:
Singh A., Singh I. (eds) Molecular Aspects of Plant-Pathogen Interaction. Springer, Singapore
18. PR pattern in R vs S
Citation : CV, Tonón & Guevara, María & Oliva, Claudia & GR, Daleo. (2002). Isolation of a Potato Acidic 39 kDa
β‐1,3‐glucanase with Antifungal Activity against Phytophthora infestans and Analysis of its Expression in Potato
Cultivars Differing in their Degrees of Field Resistance. Journal of Phytopathology. 150. 189 - 195.
10.1046/j.1439-0434.2002.00729.x.
• beta-1,3-glucanase extracted (GLU-39), The enzyme produces a direct inhibitory effect on the germination
of sporangia of P. infestans.
• In the resistant cultivar (cv Pampeana INTA) GLU-39 induction (four-fold with respect to healthy tubers)
occurred 14 h after inoculation and remained over basal levels at 38 h after inoculation.
• By contrast, in the susceptible cultivar (cv Bintje), GLU-39 was induced at lower levels than those observed
in cv Pampeana INTA, and no differences were detected between wounding and infection.
• Stronger accumulation of PRs in inoculated resistant as compared to susceptible plants
• In some pathosystems mRNAs for certain PRs members accumulate to similar levels in compatible and
incompatible interactions, but the maximum level of expression is reached much faster in the latter (Van
Kan et al., 1992)
19. Relevance of PRs to disease resistance
• Important constitutive expression of PRs in plants with high level of natural disease resistance. This
correlation was observed in several pathosystems, such as apple – Venturia inaequalis (Gau et al.,
2004)
• Significant constitutive expression of PRs in transgenic plants overexpressing PR genes accompanied
by increased resistance to pathogens. Thus, increased tolerance to Peronospora tabacina and
Phytophthora parasitica var. nicotianae was demonstrated in tobacco overexpressing PR1a gene
(Alexander et al., 1993).
• silencing of PR-1b gene in barley facilitates the penetration of the fungal pathogen Blumeria graminis f.
sp. hordei in the leaves (Schultheiss et al., 2003).
• Accumulation of PRs in plants in which resistance is locally or systemically induced
20. Commercial and engineering
• Increased resistance to crown rust disease in transgenic Italian ryegrass expressing the rice chitinase
gene was demonstrated (Takahashi et al., 2005)
• Brassica napus transgenic plants, constitutively expressing a chimeric chitinase gene, display field
tolerance to fungal pathogens (Grison et al., 1996)
• The constitutive overexpression of tobacco class I PR-2 and PR-3 transgenes in potato plants
enhanced their resistance to Phytophthora infestans, the causal agent of late blight (Bachmann et
al., 1998)
• overexpression of the cloned rice thaumatin-like (PR-5) gene in transgenic rice plants enhanced the
environmental friendly resistance to Rhizoctonia solani causing sheath blight disease (Datta et al.,
2001)
21. Conclusion
• PR proteins play important role in disease resistance, seed germination and also help the
plant to adapt to the environmental stress.
• The increasing knowledge about the PR proteins gives better idea regarding the
development and defense system of plants.
• Primary aspects of the gene regulation of the PR proteins are understood but the study of
exact mechanism of gene regulation and receptor cascade will open new ways for the
plant genetic engineering technology for crop improvement.