1. The document summarizes a seminar on how necrotrophic fungal pathogens hijack plant genes. Necrotrophs produce effector proteins called necrotrophic effectors (NEs) that interact with dominant host sensitivity genes and induce cell death.
2. Case studies of several plant-pathogen systems were described to illustrate the inverse gene-for-gene model. These include the interactions between the Tsn1 gene and T-toxin in maize, the LOV1 gene and victorin in Arabidopsis, and the Pc gene and PC-toxin in sorghum.
3. A detailed case study of the wheat gene Tsn1 that confers sensitivity to
This document describes a study that used virus-induced gene silencing (VIGS) to investigate the role of the hexose transporter gene LeHT1 in tomato resistance to Tomato yellow leaf curl virus (TYLCV). The gene was silenced in resistant and susceptible tomato lines. Silencing LeHT1 compromised resistance in resistant plants, allowing higher virus accumulation. Silenced resistant plants also developed necrosis and oxidative burst symptoms in response to TYLCV and other viruses. The results suggest LeHT1 plays a role in resistance by limiting virus entry/movement in cells and that silencing uncovered a secondary resistance mechanism involving programmed cell death.
This document discusses various mechanisms of viral resistance in plants, including coat protein-mediated resistance, non-structural protein resistance, antisense RNAs, ribozymes, movement proteins, and satellite sequences. It provides details on experiments demonstrating coat protein-mediated cross protection using tobacco mosaic virus sequences. Non-structural or replicase proteins from viruses like tobacco mosaic virus have also been used to generate resistant plants but the mechanisms are not clear. Antisense RNAs work by hybridizing with and blocking mRNA from the target gene. Ribozymes and satellite sequences have also been explored as resistance mechanisms but were not very effective. Gene silencing is another potential mechanism of viral resistance in transgenic plants.
S. prasanth kumar young scientist awarded presentationPrasanthperceptron
The document summarizes research on the coat protein of the Tomato yellow leaf curl viral (TYLCV) disease, which causes significant damage to tomato crops in India. Key findings include:
1) Sequence analysis found mutations in the coat protein that provide insights into the evolutionary divergence of Indian virus isolates and their ability to systematically infect plants.
2) Structural modeling predicted the coat protein binds double-stranded DNA through interactions facilitated by surface loops and neutral patches on the protein.
3) Docking simulations showed the coat protein binds plant DNA through electrostatic and van der Waals interactions, helping the virus infect tomato and other plants.
This document summarizes a study on silencing the Elongation factor 1-alpha (EF1α) gene in Tomato yellow leaf curl virus (TYLCV)-resistant tomato plants. The objectives were to silence EF1α and observe if resistance collapsed. Results showed that after silencing EF1α in resistant plants and inoculating with TYLCV, the resistance collapsed, as seen in increased virus infection and symptoms matching susceptible plants. It was concluded that EF1α is important for TYLCV resistance. Further study of EF1α's role in the resistance gene network was recommended.
This document summarizes the complete genomic sequence of a novel betanucleorhabdovirus identified from a Cnidium officinale plant and tentatively named Cnidium virus 1 (CnV1). The genome of CnV1 was sequenced and found to be 13,994 nucleotides in length. BLAST searches showed CnV1 is most closely related to betanucleorhabdoviruses. Several viruses have previously been reported to infect C. officinale including two secoviruses and an alphaflexivirus. This represents the first report of a betanucleorhabdovirus infecting C. officinale.
This document discusses different types of vectors that can be used for genetic engineering, including animal viruses, plant viruses, retroviruses, shuttle vectors, and binary vectors. It provides details on the structure and use of tobacco mosaic virus (TMV) as a plant viral vector, describing how foreign genes can be stably replicated and spread systemically in plants using this system. It also summarizes key features of yeast episomal plasmids (YEps), retroviral vectors based on murine leukemia virus, and the binary vector system used for plant transformation via Agrobacterium tumefaciens.
Genetic Engineering of Papaya for Ring Spot VirusAmandeep Kaur
This document summarizes the development of genetically engineered papaya in Hawaii that are resistant to Papaya Ring Spot Virus (PRSV). Researchers introduced the coat protein gene of PRSV into papaya plants, which provided resistance. Transgenic papaya plants were tested and shown to be protected from PRSV infection, while unmodified plants developed symptoms. Two new virus-resistant varieties, SunUp and Rainbow, were developed and approved for commercial production in Hawaii in 1998 to rescue the papaya industry from devastating PRSV outbreaks.
This document describes a study that used virus-induced gene silencing (VIGS) to investigate the role of the hexose transporter gene LeHT1 in tomato resistance to Tomato yellow leaf curl virus (TYLCV). The gene was silenced in resistant and susceptible tomato lines. Silencing LeHT1 compromised resistance in resistant plants, allowing higher virus accumulation. Silenced resistant plants also developed necrosis and oxidative burst symptoms in response to TYLCV and other viruses. The results suggest LeHT1 plays a role in resistance by limiting virus entry/movement in cells and that silencing uncovered a secondary resistance mechanism involving programmed cell death.
This document discusses various mechanisms of viral resistance in plants, including coat protein-mediated resistance, non-structural protein resistance, antisense RNAs, ribozymes, movement proteins, and satellite sequences. It provides details on experiments demonstrating coat protein-mediated cross protection using tobacco mosaic virus sequences. Non-structural or replicase proteins from viruses like tobacco mosaic virus have also been used to generate resistant plants but the mechanisms are not clear. Antisense RNAs work by hybridizing with and blocking mRNA from the target gene. Ribozymes and satellite sequences have also been explored as resistance mechanisms but were not very effective. Gene silencing is another potential mechanism of viral resistance in transgenic plants.
S. prasanth kumar young scientist awarded presentationPrasanthperceptron
The document summarizes research on the coat protein of the Tomato yellow leaf curl viral (TYLCV) disease, which causes significant damage to tomato crops in India. Key findings include:
1) Sequence analysis found mutations in the coat protein that provide insights into the evolutionary divergence of Indian virus isolates and their ability to systematically infect plants.
2) Structural modeling predicted the coat protein binds double-stranded DNA through interactions facilitated by surface loops and neutral patches on the protein.
3) Docking simulations showed the coat protein binds plant DNA through electrostatic and van der Waals interactions, helping the virus infect tomato and other plants.
This document summarizes a study on silencing the Elongation factor 1-alpha (EF1α) gene in Tomato yellow leaf curl virus (TYLCV)-resistant tomato plants. The objectives were to silence EF1α and observe if resistance collapsed. Results showed that after silencing EF1α in resistant plants and inoculating with TYLCV, the resistance collapsed, as seen in increased virus infection and symptoms matching susceptible plants. It was concluded that EF1α is important for TYLCV resistance. Further study of EF1α's role in the resistance gene network was recommended.
This document summarizes the complete genomic sequence of a novel betanucleorhabdovirus identified from a Cnidium officinale plant and tentatively named Cnidium virus 1 (CnV1). The genome of CnV1 was sequenced and found to be 13,994 nucleotides in length. BLAST searches showed CnV1 is most closely related to betanucleorhabdoviruses. Several viruses have previously been reported to infect C. officinale including two secoviruses and an alphaflexivirus. This represents the first report of a betanucleorhabdovirus infecting C. officinale.
This document discusses different types of vectors that can be used for genetic engineering, including animal viruses, plant viruses, retroviruses, shuttle vectors, and binary vectors. It provides details on the structure and use of tobacco mosaic virus (TMV) as a plant viral vector, describing how foreign genes can be stably replicated and spread systemically in plants using this system. It also summarizes key features of yeast episomal plasmids (YEps), retroviral vectors based on murine leukemia virus, and the binary vector system used for plant transformation via Agrobacterium tumefaciens.
Genetic Engineering of Papaya for Ring Spot VirusAmandeep Kaur
This document summarizes the development of genetically engineered papaya in Hawaii that are resistant to Papaya Ring Spot Virus (PRSV). Researchers introduced the coat protein gene of PRSV into papaya plants, which provided resistance. Transgenic papaya plants were tested and shown to be protected from PRSV infection, while unmodified plants developed symptoms. Two new virus-resistant varieties, SunUp and Rainbow, were developed and approved for commercial production in Hawaii in 1998 to rescue the papaya industry from devastating PRSV outbreaks.
1. Bovine papillomavirus (BPV) vectors utilize the circular, double-stranded DNA genome of BPV. The BPV genome contains early and late regions and can transform cells without integrating.
2. There are three main types of BPV vectors. All contain the transforming 69% fragment of BPV and bacterial sequences. One type inserts a gene of interest, another adds a stimulating gene, and the third uses the full BPV genome.
3. Transformation efficiency is highest with the full BPV genome due to an enhancer in the non-transforming region. Stimulating genes can replace this enhancer's function when parts of the genome are removed. BPV vectors provide amplified
This document discusses plant virus induced genes. It explains that after a plant virus enters a host, it can induce genes that lead to either susceptibility or resistance. Susceptible genes provide conditions that allow for a successful viral infection, while resistance genes create antiviral conditions that prevent infection. Virus induced genes can also impact host metabolism and physiology. The document provides examples of susceptible genes involved in viral replication, movement, and suppression of gene silencing defenses.
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
This document summarizes a study that used virus-induced gene silencing (VIGS) to identify host genes involved in Tomato yellow leaf curl virus (TYLCV) infection of Nicotiana benthamiana plants. Researchers screened 54 candidate host genes and found that silencing 18 of them altered TYLCV infection based on effects on GFP expression patterns. Silencing of 7 genes had an antiviral effect by reducing viral DNA accumulation, while silencing of 11 other genes promoted infection by increasing viral DNA levels. Most notably, silencing of the deltaCOP subunit completely abolished TYLCV accumulation.
The researchers designed a genetic switch to conditionally control and track gene expression in bacteria. The switch uses the tetracycline repressor system, where the presence of the inducer anhydrotetracycline (aTc) allows expression of a gene of interest. They constructed a plasmid with constitutive red fluorescent protein expression and aTc-inducible green fluorescent protein. Initial versions showed poor repression, but optimizing the ribosome binding site of the tetracycline repressor gene yielded a functional switch with visible induction of green fluorescence with aTc. This switch will allow studying effects of gene expression on bacterial behaviors in future experiments.
ROLE OF Agrobacterium in plant pathology pradeep m
- Agrobacterium tumefaciens is a soil bacterium that causes crown gall disease in plants by transferring tumor-inducing (Ti) plasmid DNA to host cells.
- The Ti plasmid contains genes (vir genes) required for T-DNA processing and transfer to plant cells. A key vir gene is virE2, which encodes a single-stranded DNA binding protein.
- A study introduced the virE2 gene into Nicotiana benthamiana plants to test if it provides tolerance against Sri Lankan cassava mosaic virus (SLCMV), a geminivirus.
- Results showed that virE2 reduced SLCMV infection symptoms and spread in transgenic N. bent
Physiological effects of virus infected plants78686
This document summarizes the physiological effects of virus-infected plants. It discusses how viruses use host cell machinery to replicate their genomes and produce viral proteins, which can disturb host cell balance. This leads to various symptoms, like chlorosis and necrosis. On a cellular level, it impacts nucleic acids, proteins, lipids, carbohydrates, cell walls, respiration, photosynthesis, transpiration, and specific enzyme activities. During active viral replication, it may divert carbon fixation away from sugars towards amino acids and organic acids to produce building blocks for viral components. Overall, viral infection generally reduces photosynthetic activity through various biochemical and physical changes to the host cell.
This document discusses post-transcriptional gene silencing (PTGS) in plants. It describes key discoveries such as Jorgensen discovering PTGS in 1990 by observing unexpected white color sectors in transgenic plants aimed at increasing pigment production. It also discusses mechanisms of RNA interference (RNAi) such as the two major pathways of microRNA and small interfering RNA (siRNA). Additionally, it examines gene silencing induced by geminiviruses and transgenes in plants. Various constructs and viral proteins that affect RNA silencing suppression are also reviewed.
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.
Cloning and sequence analysis of banana streak virus dna. harper 1998Paloma Susan
Banana streak virus (BSV) causes severe problems for banana cultivation. The researchers cloned and sequenced the genome of a Nigerian isolate of BSV. The genome was found to be 7,389 base pairs and organized similarly to other badnaviruses, with three open reading frames. Comparison showed BSV is distinct from but closely related to sugarcane bacilliform virus. PCR primers designed from the sequence data detected BSV sequences in banana plants, indicating portions of the BSV genome may integrate into the banana genome. The BSV sequence provides a basis for more sensitive PCR-based detection methods.
This document summarizes research on the IFNγ receptor and signaling pathway. It describes how the receptor was initially characterized through ligand binding studies in the 1980s. Genetic experiments in the late 1980s showed the receptor requires two subunits for signaling. The α subunit binds IFNγ specifically, while the β subunit is required for response induction. The JAK-STAT signaling pathway was also discovered in the 1980s-1990s, linking receptor activation to gene transcription. In 1994, it was shown that IFNγ induces tyrosine phosphorylation of the α subunit, creating a docking site for STAT1 and linking the receptor to the JAK-STAT pathway. This provided a comprehensive model of IFNγ receptor signaling.
Plant transformation vectors and their typesZahra Naz
This document summarizes a presentation on plant transformation vectors and their types. It discusses various types of vectors used for plant transformation including plasmids, viruses, bacteriophages, and cosmids. Plasmids are the most commonly used vector for plant transformation. Agrobacterium-mediated transformation using tumor-inducing (Ti) plasmids is an effective method for genetically transforming plants. Viral vectors like cauliflower mosaic virus (CaMV) are also used but have certain limitations.
Introduction
Ti plasmid
Agrobacterium tumefaciens
Ti plasmid structure
Overview of infection process
Ti plasmid derived vector systems
Cointegrate vectors
Binary vectors
Agrobacterium mediated transformation of explants
Conclusions
References
Viruses infect plants through wounds or insect vectors and use host cell machinery to replicate their genomes and produce proteins. They move between cells via plasmodesmata or transport streams. Pathogenesis involves implantation, local replication, spread to target organs, and shedding from the plant. Strategies to control plant viruses include eliminating sources and infected plants, controlling vectors, breeding resistance, and using cross-protection methods like satellite RNAs or transgenic expression of antiviral genes. RNA interference is now a primary tool for inducing virus resistance by degrading viral genomes.
A brief outline of the antiviral strategies using RNA silencing pathways with special emphasis on artificial miRNA for broad spectrum virus resistance in plants
The document classifies and describes different types of viruses based on their host. It discusses plant viruses, animal viruses, and bacteria viruses (bacteriophages). Plant viruses can infect plant cells and are classified based on their structure. They are transmitted through sap, insects, nematodes, seeds and pollen. Animal viruses are divided into vertebrate viruses like pox, herpes and adenovirus, and invertebrate viruses that infect arthropods and baculovirus. Bacteriophages, or bacteria viruses, can undergo lytic or lysogenic cycles when infecting bacteria. The document also discusses applications of plant viruses, bacteriophages, and their potential medical use.
The document summarizes key details about Tobacco Mosaic Virus (TMV), including its history, structure, and replication process. It notes that TMV was the first virus to be purified and shown to consist of protein and nucleic acid. Studies in the 1930s-1940s revealed that TMV has a rod-shaped structure consisting of a protein coat containing a single strand of RNA. The RNA acts as a template for the virus to replicate by synthesizing more copies of itself within the host plant cell. TMV remains an important model system for understanding viral structure and replication.
The Potyviridae is the largest family of plant viruses, containing over 190 species divided among 10 genera. Members have filamentous particles and positive-sense single stranded RNA genomes. The largest and most agriculturally important genus is Potyvirus, which infects a wide range of plants and is transmitted by aphids. Other genera include Rymovirus and Tritimovirus which are transmitted by mites, and Bymovirus and Ipomovirus which have segmented genomes and are transmitted by fungi or whiteflies respectively. The family contains many viruses of agricultural importance.
It is a part of Ti Plasmid which takes part intransfer and integration of T-DNA into plant chromosome.
The vir sequence consist of 8 operons which take part in different functions associated with virulence of Ti Plasmid. These are vir H, vir A, vir B, vir G, vir C, vir D, vir E, & vir F. ( vir H & vir F present occasionally).
This document discusses non-host resistance in plants. It begins with an introduction and outline. It then discusses the components of non-host resistance, including preformed defenses, inducible defenses, defense signaling, and broad-spectrum resistance genes. It provides examples of different types of non-host resistance and applications in agriculture. The document also summarizes several studies examining the role of specific genes and signaling molecules in non-host resistance through experiments in model plants like Arabidopsis.
Tobacco ring e3 ligase nt rfp1 mediates romanceRomanceManna
This journal club presentation summarizes a research article that investigated the interaction between the Tobacco RING E3 Ligase NtRFP1 and the betasatellite-encoded βC1 protein of the Geminivirus Tomato yellow leaf curl China virus. The presentation identifies that NtRFP1 interacts with βC1 and functions as an E3 ubiquitin ligase that mediates the ubiquitination and proteasomal degradation of βC1. This degradation of the βC1 pathogenicity determinant by NtRFP1 affects βC1-induced symptoms. In conclusion, the study finds that the βC1 protein is targeted for degradation by the host plant's ubiquitin-proteasome system through
1. Bovine papillomavirus (BPV) vectors utilize the circular, double-stranded DNA genome of BPV. The BPV genome contains early and late regions and can transform cells without integrating.
2. There are three main types of BPV vectors. All contain the transforming 69% fragment of BPV and bacterial sequences. One type inserts a gene of interest, another adds a stimulating gene, and the third uses the full BPV genome.
3. Transformation efficiency is highest with the full BPV genome due to an enhancer in the non-transforming region. Stimulating genes can replace this enhancer's function when parts of the genome are removed. BPV vectors provide amplified
This document discusses plant virus induced genes. It explains that after a plant virus enters a host, it can induce genes that lead to either susceptibility or resistance. Susceptible genes provide conditions that allow for a successful viral infection, while resistance genes create antiviral conditions that prevent infection. Virus induced genes can also impact host metabolism and physiology. The document provides examples of susceptible genes involved in viral replication, movement, and suppression of gene silencing defenses.
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
This document summarizes a study that used virus-induced gene silencing (VIGS) to identify host genes involved in Tomato yellow leaf curl virus (TYLCV) infection of Nicotiana benthamiana plants. Researchers screened 54 candidate host genes and found that silencing 18 of them altered TYLCV infection based on effects on GFP expression patterns. Silencing of 7 genes had an antiviral effect by reducing viral DNA accumulation, while silencing of 11 other genes promoted infection by increasing viral DNA levels. Most notably, silencing of the deltaCOP subunit completely abolished TYLCV accumulation.
The researchers designed a genetic switch to conditionally control and track gene expression in bacteria. The switch uses the tetracycline repressor system, where the presence of the inducer anhydrotetracycline (aTc) allows expression of a gene of interest. They constructed a plasmid with constitutive red fluorescent protein expression and aTc-inducible green fluorescent protein. Initial versions showed poor repression, but optimizing the ribosome binding site of the tetracycline repressor gene yielded a functional switch with visible induction of green fluorescence with aTc. This switch will allow studying effects of gene expression on bacterial behaviors in future experiments.
ROLE OF Agrobacterium in plant pathology pradeep m
- Agrobacterium tumefaciens is a soil bacterium that causes crown gall disease in plants by transferring tumor-inducing (Ti) plasmid DNA to host cells.
- The Ti plasmid contains genes (vir genes) required for T-DNA processing and transfer to plant cells. A key vir gene is virE2, which encodes a single-stranded DNA binding protein.
- A study introduced the virE2 gene into Nicotiana benthamiana plants to test if it provides tolerance against Sri Lankan cassava mosaic virus (SLCMV), a geminivirus.
- Results showed that virE2 reduced SLCMV infection symptoms and spread in transgenic N. bent
Physiological effects of virus infected plants78686
This document summarizes the physiological effects of virus-infected plants. It discusses how viruses use host cell machinery to replicate their genomes and produce viral proteins, which can disturb host cell balance. This leads to various symptoms, like chlorosis and necrosis. On a cellular level, it impacts nucleic acids, proteins, lipids, carbohydrates, cell walls, respiration, photosynthesis, transpiration, and specific enzyme activities. During active viral replication, it may divert carbon fixation away from sugars towards amino acids and organic acids to produce building blocks for viral components. Overall, viral infection generally reduces photosynthetic activity through various biochemical and physical changes to the host cell.
This document discusses post-transcriptional gene silencing (PTGS) in plants. It describes key discoveries such as Jorgensen discovering PTGS in 1990 by observing unexpected white color sectors in transgenic plants aimed at increasing pigment production. It also discusses mechanisms of RNA interference (RNAi) such as the two major pathways of microRNA and small interfering RNA (siRNA). Additionally, it examines gene silencing induced by geminiviruses and transgenes in plants. Various constructs and viral proteins that affect RNA silencing suppression are also reviewed.
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.
Cloning and sequence analysis of banana streak virus dna. harper 1998Paloma Susan
Banana streak virus (BSV) causes severe problems for banana cultivation. The researchers cloned and sequenced the genome of a Nigerian isolate of BSV. The genome was found to be 7,389 base pairs and organized similarly to other badnaviruses, with three open reading frames. Comparison showed BSV is distinct from but closely related to sugarcane bacilliform virus. PCR primers designed from the sequence data detected BSV sequences in banana plants, indicating portions of the BSV genome may integrate into the banana genome. The BSV sequence provides a basis for more sensitive PCR-based detection methods.
This document summarizes research on the IFNγ receptor and signaling pathway. It describes how the receptor was initially characterized through ligand binding studies in the 1980s. Genetic experiments in the late 1980s showed the receptor requires two subunits for signaling. The α subunit binds IFNγ specifically, while the β subunit is required for response induction. The JAK-STAT signaling pathway was also discovered in the 1980s-1990s, linking receptor activation to gene transcription. In 1994, it was shown that IFNγ induces tyrosine phosphorylation of the α subunit, creating a docking site for STAT1 and linking the receptor to the JAK-STAT pathway. This provided a comprehensive model of IFNγ receptor signaling.
Plant transformation vectors and their typesZahra Naz
This document summarizes a presentation on plant transformation vectors and their types. It discusses various types of vectors used for plant transformation including plasmids, viruses, bacteriophages, and cosmids. Plasmids are the most commonly used vector for plant transformation. Agrobacterium-mediated transformation using tumor-inducing (Ti) plasmids is an effective method for genetically transforming plants. Viral vectors like cauliflower mosaic virus (CaMV) are also used but have certain limitations.
Introduction
Ti plasmid
Agrobacterium tumefaciens
Ti plasmid structure
Overview of infection process
Ti plasmid derived vector systems
Cointegrate vectors
Binary vectors
Agrobacterium mediated transformation of explants
Conclusions
References
Viruses infect plants through wounds or insect vectors and use host cell machinery to replicate their genomes and produce proteins. They move between cells via plasmodesmata or transport streams. Pathogenesis involves implantation, local replication, spread to target organs, and shedding from the plant. Strategies to control plant viruses include eliminating sources and infected plants, controlling vectors, breeding resistance, and using cross-protection methods like satellite RNAs or transgenic expression of antiviral genes. RNA interference is now a primary tool for inducing virus resistance by degrading viral genomes.
A brief outline of the antiviral strategies using RNA silencing pathways with special emphasis on artificial miRNA for broad spectrum virus resistance in plants
The document classifies and describes different types of viruses based on their host. It discusses plant viruses, animal viruses, and bacteria viruses (bacteriophages). Plant viruses can infect plant cells and are classified based on their structure. They are transmitted through sap, insects, nematodes, seeds and pollen. Animal viruses are divided into vertebrate viruses like pox, herpes and adenovirus, and invertebrate viruses that infect arthropods and baculovirus. Bacteriophages, or bacteria viruses, can undergo lytic or lysogenic cycles when infecting bacteria. The document also discusses applications of plant viruses, bacteriophages, and their potential medical use.
The document summarizes key details about Tobacco Mosaic Virus (TMV), including its history, structure, and replication process. It notes that TMV was the first virus to be purified and shown to consist of protein and nucleic acid. Studies in the 1930s-1940s revealed that TMV has a rod-shaped structure consisting of a protein coat containing a single strand of RNA. The RNA acts as a template for the virus to replicate by synthesizing more copies of itself within the host plant cell. TMV remains an important model system for understanding viral structure and replication.
The Potyviridae is the largest family of plant viruses, containing over 190 species divided among 10 genera. Members have filamentous particles and positive-sense single stranded RNA genomes. The largest and most agriculturally important genus is Potyvirus, which infects a wide range of plants and is transmitted by aphids. Other genera include Rymovirus and Tritimovirus which are transmitted by mites, and Bymovirus and Ipomovirus which have segmented genomes and are transmitted by fungi or whiteflies respectively. The family contains many viruses of agricultural importance.
It is a part of Ti Plasmid which takes part intransfer and integration of T-DNA into plant chromosome.
The vir sequence consist of 8 operons which take part in different functions associated with virulence of Ti Plasmid. These are vir H, vir A, vir B, vir G, vir C, vir D, vir E, & vir F. ( vir H & vir F present occasionally).
This document discusses non-host resistance in plants. It begins with an introduction and outline. It then discusses the components of non-host resistance, including preformed defenses, inducible defenses, defense signaling, and broad-spectrum resistance genes. It provides examples of different types of non-host resistance and applications in agriculture. The document also summarizes several studies examining the role of specific genes and signaling molecules in non-host resistance through experiments in model plants like Arabidopsis.
Tobacco ring e3 ligase nt rfp1 mediates romanceRomanceManna
This journal club presentation summarizes a research article that investigated the interaction between the Tobacco RING E3 Ligase NtRFP1 and the betasatellite-encoded βC1 protein of the Geminivirus Tomato yellow leaf curl China virus. The presentation identifies that NtRFP1 interacts with βC1 and functions as an E3 ubiquitin ligase that mediates the ubiquitination and proteasomal degradation of βC1. This degradation of the βC1 pathogenicity determinant by NtRFP1 affects βC1-induced symptoms. In conclusion, the study finds that the βC1 protein is targeted for degradation by the host plant's ubiquitin-proteasome system through
The document discusses plant disease resistance genes (R-genes) and their importance in crop breeding for disease resistance. It contains the following key points:
1. R-genes encode receptors that recognize pathogen effector proteins and trigger plant immune responses. Most R-genes contain nucleotide binding and leucine-rich repeat domains.
2. Dozens of R-genes have been cloned from various plants using map-based cloning, transposon tagging, or a new method called MutRenSeq that enriches for R-gene sequences.
3. Introducing R-genes from wild crop relatives into domestic crops can provide natural and sustainable resistance to diseases while avoiding pesticide use and potential environmental damage.
This document summarizes a seminar on plant immunity and its implications for plant breeding. It discusses the gene-for-gene hypothesis where plants have resistance genes corresponding to pathogen avirulence genes. It describes the three phases of plant immunity: PAMP-triggered immunity, effector-triggered susceptibility, and effector-triggered immunity. Defense responses include stomatal closure, ion fluxes, oxidative bursts, phytohormone action, hypersensitive response, and systemic acquired resistance. The document outlines breeding and biotechnological strategies to induce plant immunity, such as manipulating PAMP receptors, pyramiding R genes, and expressing antifungal fusion proteins.
The number of sequenced genes having unknown function continues to climb with the continuing decrease in the cost of genome sequencing. In Reverse Genetics (RG), functions of known genes are investigated with targeted modulation of gene activity, and hypothesis regarding gene function directly tested in vivo. Several RG approaches like insertional mutagenesis, fast neutron mutagenesis, TILLING and RNA interference have led to the identification of mutations in candidate genes and subsequent phenotypic analysis of these mutants.
Okabe et al. (2011) employed TILLING technique to screen six ethylene receptor genes in tomato (SlETR1–SlETR6) and two allelic mutants of SlETR1 (Sletr1-1 and Sletr1-2) with reduced ethylene response were identified. Using fast neutron mutagenesis, Li et al. (2001) obtained arabidopsis deletion mutants for bZIP transcription factor viz. AHBP 1b and OBF 5, a key regulator for systemic acquired resistance but their role were compensated by other regulatory factors in mutants. Terada et al. (2007) successfully blocked the expression of the Adh 2 gene through homologous recombination followed by transgenesis in rice however phenotype could not be determined since no differences were observed between wild and transgenic plants. RNA interference (RNAi) works as sequence-specific gene regulation and has been used in determination of function of many genes. Saurabh et al. (2014) reviewed the impact of RNAi in crop improvement and found its application in improvement of nutritional aspects, biotic and abiotic stresses, morphol¬ogy, crafting male sterility, enhanced secondary metabolite synthesis.
In addition, new advances in technology and reduction in sequencing cost may soon make it practical to use whole genome sequencing or gene targeting like ZFN technology and TAL effectors technology on a routine basis to identify or generate mutations in specific genes. Scholze and Boch (2011) mentioned that TAL effectors technology is more specific and predictable than ZFN. RG techniques have their own advantages and disadvantages depending on the species being targeted and the questions being addressed. Finally, with the continuous development of new technologies, the most efficient RG technique in the future may involve high throughput direct sequencing of part or complete genomes of individual plants followed by efficient novel tools to determine the function for utilization in crop improvement.
This research article describes how plant pathogens have evolved to counteract central nodes of plant immune receptor networks. The researchers screened 165 pathogen effectors and identified 5 that suppressed cell death triggered by NLR immune receptors called NRCs. Further analysis showed that a cyst nematode effector and an oomycete effector specifically inhibited the function of two NRC proteins, NRC2 and NRC3, but not NRC4. The nematode effector bound directly to NRC2 and NRC3, while the oomycete effector acted through a host membrane trafficking protein to suppress NRC responses. This suggests that different pathogens have independently evolved effectors that target central nodes of the plant NLR network to promote infection. Coevolution with such
History
Host pathogen interaction
R gene
Molecular techniques for detection of plant pathogens
Role of molecular techniques in resistance breeding Deployment of R genes and linked markers
Transgenic approaches in plant protection
Conclusion
Transcript profiling is used to study gene expression during plant-pathogen interactions. Methods like northern blotting, microarrays, and SAGE analysis are used to analyze changes in host and pathogen transcription during infection. Basal defense responses in the host like accumulation of salicylic acid help resist pathogens. Successful pathogens suppress host defenses through effectors and modulate expression of host genes involved in senescence and cell death. The interaction outcome depends on the interplay between pathogen effectors and host resistance genes.
Plant immunity towards an integrated view of plant pathogen interaction and i...Pavan R
This document discusses plant immunity and pathogen interactions. It provides an overview of the different forms of plant resistance including antipathy, hindrance, and defense. It describes the phases of plant immunity including PAMP-triggered immunity, effector-triggered susceptibility, and effector-triggered immunity. It also discusses various defense responses in plants against pathogens such as stomatal closure, ion fluxes, oxidative burst, role of phytohormones, hypersensitive response, and systemic acquired resistance. Finally, it summarizes some breeding and biotechnological strategies used to induce resistance in plants like manipulating PAMP receptors, gene pyramiding, use of resistance genes and antifungal fusion proteins, and utilization of phytoalexins.
importance of pathogenomics in plant pathologyvinay ju
The document provides an outline for a seminar on pathogenomics for diagnosis and management of plant diseases. It includes sections on pathogenomics in plant pathology, diagnostic tools using next-generation sequencing technologies, host-microbe interaction and genes involved in virulence and resistance. The outline also lists various bioinformatics databases and molecular techniques used for pathogen detection, including PCR-based methods and microarrays. It discusses several examples of pathogenicity genes and host proteins involved in plant-virus interactions.
The IOSR Journal of Pharmacy (IOSRPHR) is an open access online & offline peer reviewed international journal, which publishes innovative research papers, reviews, mini-reviews, short communications and notes dealing with Pharmaceutical Sciences( Pharmaceutical Technology, Pharmaceutics, Biopharmaceutics, Pharmacokinetics, Pharmaceutical/Medicinal Chemistry, Computational Chemistry and Molecular Drug Design, Pharmacognosy & Phytochemistry, Pharmacology, Pharmaceutical Analysis, Pharmacy Practice, Clinical and Hospital Pharmacy, Cell Biology, Genomics and Proteomics, Pharmacogenomics, Bioinformatics and Biotechnology of Pharmaceutical Interest........more details on Aim & Scope).
All manuscripts are subject to rapid peer review. Those of high quality (not previously published and not under consideration for publication in another journal) will be published without delay.
Plant pathogens interact with host plants through complex immune systems. There are three main phases of plant immunity: PAMP-triggered immunity (PTI), effector-triggered susceptibility (ETS), and effector-triggered immunity (ETI). PTI involves pattern recognition receptors that detect pathogen-associated molecular patterns. ETS occurs when pathogen effectors suppress PTI and cause disease. ETI is a stronger response triggered when host resistance proteins detect pathogen effectors. Breeding strategies to improve plant immunity include pyramiding resistance genes from wild relatives and manipulating PTI receptors.
Photorhabdus bacteria have a mutualistic relationship with nematodes, where they help the nematodes infect and kill insects. These bacteria produce bioluminescence, toxins, and other compounds that help overcome the insects' immune systems. While usually symbiotic with nematodes in insects, some Photorhabdus strains can also infect humans. The bacteria have evolved complex interactions with their hosts and produce many secondary metabolites worth studying for new drug development.
This document discusses the interplay between Mycobacterium tuberculosis (Mtb) and the host immune environment, particularly in the context of HIV/TB co-infection. It presents several key findings:
1. Mtb can detect and respond to environmental cues within the macrophage such as oxidative stress, nutrient limitation, and changes in pH and chloride concentration. This allows Mtb to sense its intracellular location and immune status.
2. Reporter strains of Mtb show an accelerated transcriptional response to stresses like nitric oxide in vaccinated mice, indicating the immune response is developing faster.
3. Drugs like isoniazid have greater activity against intracellular Mtb in naive mice, suggesting the bacteria replicate more in this
1. Genetic engineering has been used to develop transgenic plants with resistance to nematodes by expressing antifeedant and nematicidal proteins. This includes expressing cysteine protease inhibitors like oryzacystatin that interfere with nematode digestion and reproduction.
2. RNA interference techniques have also been used to disrupt essential nematode genes through plant expression of double stranded RNA, reducing nematode infectivity and reproduction.
3. Some nematode resistance genes from crops and their wild relatives have been identified and cloned, including the Hs1pro-1 gene from sugar beet and the Mi-1 gene from tomato, which confers resistance through hypersensitive response.
This document discusses human genetics research into infectious diseases. It summarizes that:
1) Genetic factors contribute to variability in individual responses to infection exposure and clinical outcomes. Rare single gene mutations can cause highly selective predispositions to specific pathogens like Herpes simplex virus-1 or mycobacteria.
2) Research has identified genetic causes of severe infectious diseases like Herpes simplex encephalitis and Mendelian susceptibility to mycobacterial disease. Defects in the TLR3 and IL-12/IFN-γ pathways increase risk.
3) Genome-wide studies of common infections like tuberculosis have found limited roles for common variants but suggest searching for rare variants using deep sequencing. Gen
Intracellular highways in the plants: the role of the cytoskeleton in camv i...CIAT
The document discusses research on the intracellular movement of Cauliflower Mosaic Virus (CaMV) particles. It finds that the CaMV P6 protein forms motile inclusion bodies that traffic along the plant cell's actin microfilaments and stabilize microtubules. The P6 inclusion bodies are hypothesized to function as "virion factories" where CaMV particles assemble before being transported to plasmodesmata for movement between cells. A yeast two-hybrid screen identified the host protein CHUP1, which mediates chloroplast movement along microfilaments, as interacting with P6. Silencing CHUP1 reduced the rate of CaMV lesion development, supporting its role in P6 inclusion body movement.
"Introns: Structure and Functions" during November, 2011 (Friday Seminar activity, Department of Biotechnology, University of Agricultural Sciences, Dharwad, Karnataka) by Yogesh S Bhagat (Ph D Scholar)
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Sérgio Sacani
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
Anti-Universe And Emergent Gravity and the Dark UniverseSérgio Sacani
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional ‘dark’ gravitational force describing the ‘elastic’ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton’s constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional ‘dark gravity force’ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
Microbial interaction
Microorganisms interacts with each other and can be physically associated with another organisms in a variety of ways.
One organism can be located on the surface of another organism as an ectobiont or located within another organism as endobiont.
Microbial interaction may be positive such as mutualism, proto-cooperation, commensalism or may be negative such as parasitism, predation or competition
Types of microbial interaction
Positive interaction: mutualism, proto-cooperation, commensalism
Negative interaction: Ammensalism (antagonism), parasitism, predation, competition
I. Mutualism:
It is defined as the relationship in which each organism in interaction gets benefits from association. It is an obligatory relationship in which mutualist and host are metabolically dependent on each other.
Mutualistic relationship is very specific where one member of association cannot be replaced by another species.
Mutualism require close physical contact between interacting organisms.
Relationship of mutualism allows organisms to exist in habitat that could not occupied by either species alone.
Mutualistic relationship between organisms allows them to act as a single organism.
Examples of mutualism:
i. Lichens:
Lichens are excellent example of mutualism.
They are the association of specific fungi and certain genus of algae. In lichen, fungal partner is called mycobiont and algal partner is called
II. Syntrophism:
It is an association in which the growth of one organism either depends on or improved by the substrate provided by another organism.
In syntrophism both organism in association gets benefits.
Compound A
Utilized by population 1
Compound B
Utilized by population 2
Compound C
utilized by both Population 1+2
Products
In this theoretical example of syntrophism, population 1 is able to utilize and metabolize compound A, forming compound B but cannot metabolize beyond compound B without co-operation of population 2. Population 2is unable to utilize compound A but it can metabolize compound B forming compound C. Then both population 1 and 2 are able to carry out metabolic reaction which leads to formation of end product that neither population could produce alone.
Examples of syntrophism:
i. Methanogenic ecosystem in sludge digester
Methane produced by methanogenic bacteria depends upon interspecies hydrogen transfer by other fermentative bacteria.
Anaerobic fermentative bacteria generate CO2 and H2 utilizing carbohydrates which is then utilized by methanogenic bacteria (Methanobacter) to produce methane.
ii. Lactobacillus arobinosus and Enterococcus faecalis:
In the minimal media, Lactobacillus arobinosus and Enterococcus faecalis are able to grow together but not alone.
The synergistic relationship between E. faecalis and L. arobinosus occurs in which E. faecalis require folic acid
Travis Hills of MN is Making Clean Water Accessible to All Through High Flux ...Travis Hills MN
By harnessing the power of High Flux Vacuum Membrane Distillation, Travis Hills from MN envisions a future where clean and safe drinking water is accessible to all, regardless of geographical location or economic status.
Authoring a personal GPT for your research and practice: How we created the Q...Leonel Morgado
Thematic analysis in qualitative research is a time-consuming and systematic task, typically done using teams. Team members must ground their activities on common understandings of the major concepts underlying the thematic analysis, and define criteria for its development. However, conceptual misunderstandings, equivocations, and lack of adherence to criteria are challenges to the quality and speed of this process. Given the distributed and uncertain nature of this process, we wondered if the tasks in thematic analysis could be supported by readily available artificial intelligence chatbots. Our early efforts point to potential benefits: not just saving time in the coding process but better adherence to criteria and grounding, by increasing triangulation between humans and artificial intelligence. This tutorial will provide a description and demonstration of the process we followed, as two academic researchers, to develop a custom ChatGPT to assist with qualitative coding in the thematic data analysis process of immersive learning accounts in a survey of the academic literature: QUAL-E Immersive Learning Thematic Analysis Helper. In the hands-on time, participants will try out QUAL-E and develop their ideas for their own qualitative coding ChatGPT. Participants that have the paid ChatGPT Plus subscription can create a draft of their assistants. The organizers will provide course materials and slide deck that participants will be able to utilize to continue development of their custom GPT. The paid subscription to ChatGPT Plus is not required to participate in this workshop, just for trying out personal GPTs during it.
Immersive Learning That Works: Research Grounding and Paths ForwardLeonel Morgado
We will metaverse into the essence of immersive learning, into its three dimensions and conceptual models. This approach encompasses elements from teaching methodologies to social involvement, through organizational concerns and technologies. Challenging the perception of learning as knowledge transfer, we introduce a 'Uses, Practices & Strategies' model operationalized by the 'Immersive Learning Brain' and ‘Immersion Cube’ frameworks. This approach offers a comprehensive guide through the intricacies of immersive educational experiences and spotlighting research frontiers, along the immersion dimensions of system, narrative, and agency. Our discourse extends to stakeholders beyond the academic sphere, addressing the interests of technologists, instructional designers, and policymakers. We span various contexts, from formal education to organizational transformation to the new horizon of an AI-pervasive society. This keynote aims to unite the iLRN community in a collaborative journey towards a future where immersive learning research and practice coalesce, paving the way for innovative educational research and practice landscapes.
Sexuality - Issues, Attitude and Behaviour - Applied Social Psychology - Psyc...PsychoTech Services
A proprietary approach developed by bringing together the best of learning theories from Psychology, design principles from the world of visualization, and pedagogical methods from over a decade of training experience, that enables you to: Learn better, faster!
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...Sérgio Sacani
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
�
(
�
−
�
)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
�
Ca-rich population. Although such an object is too red for any low-
�
cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
�
) with
Λ
CDM. Therefore unlike low-
�
Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
�
truly diverge from their low-
�
counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...
Gpb minor seminor
1. ICAR-INDIAN AGRICULTURAL
RESEARCH INSTITUTE
DIVISION OF PLANT PATHOLOGY
“Plant genes hijackedby necrotrophic fungal pathogens”
Credit seminar in Division of Genetics
GP691-2018
Seminar leader: Dr. Shailendra Jha
Chairperson: Dr. T. Prameela Devi
Speaker: Chaithra, M.
11580
PhD 1st year
2. FLOW OF SEMINAR…….
Introduction
Brief review of PTS, PTI,ETI and ETS
Mode for signaling events of plant-pathogenic interaction
Necrotrophic effectors
Classic gene for gene model v/s inverse gene for gene model
Different NEs gene-necrotrophic sensitivity gene interactions
Case studies
Conclusion
3. 3Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
INTRODUCTION
Types of plant pathogenic fungi (based on life cycle of pathogens)
Biotrophic Fungi Necrotrophic Fungi Hemibiotrophic Fungi
Ex: Erysiphe, Ustilago,
DM fungi, Rust fungi,
Cladosporium etc.,
Ex : Rhizoctonia, Pythium,
Alternaria, Botrytis,
Sclerotium etc.,
Ex: Phytophthora,
Pyricularia, Colletotrichum,
Bipolaris etc.,
4. 4Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
Pathogen Infection and Host Defence: Continuous battlePAMP Triggered Immunity (PTI)
Effector Triggered Susceptibility (ETS)
Effector Triggered Immunity (ETI)
Pathogen
PAMP
Effector
(Avr)
PTI ETS ETI
Avr-R
Effector
(Avr)
Avr-R
ETS ETI
AmplitudeofDefence
High
Low
Threshold for HR
Threshold for
Effective
resistancePAMP-PRR
5. 5Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
Bent and Mackey, 2007
Model for the signaling events in plant-biotroph interactionsModel for the signaling events in plant-necrotroph interactions
6. Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
• NE: Host specific toxin (HST)
• NE: cell-wall degrading enzymes, proteins, or secondary metabolites
• Almost all NE produced from Dothideomycetes class of fungi
• Production of NE recognized by specific dominant host genes known as
NE sensitivity gene. Which leading to plant-induced cell death along with
other hallmarks of a ‘resistance’ response (upregulation of defense
response genes, an oxidative burst, and MAP-kinase signaling etc.,)
Necrotrophic effectors (NE)
Plant Pathogen
Species Gene class location species NE/toxi
n
structure Comparitive
ineraction
Zea mays
(Maize)
T-urf13 unique Mitochondrial
plasmamembrane
Cochilobolus
heterostrophus
T-toxin Linear
polyketide
Distruption of mt
activity
Arabidopsis
thaliana
LOV1 NLB cytoplasma Cochilobololus victorae Victorin Cyclic
pentapptid
e
Induction of host
program cell death and
defense response
Sorghum bicolor
(Sorghum)
Pc NLB cytoplasma Periconia circinata PC-toxin Peptidyl
chlorinated
polyketide
Induction of host
program cell death and
defense response
Triticum
aestivum
(wheat)
Tsn1 PK-
NLR
cytoplasma Parastagonospora
nodorum, Pyrenophora
tritici repents, Bipolaris
sorokiniana
SnToxA,
PtrTox,
BsToxA,
13.2 kDa
protein
Induction of host
program cell death and
defense response
Triticum
aestivum
(wheat)
Snn1 WAK Plasmamembrane Parastagonospora
nodorum
SnTox1 10.3 kDa
protein
Induction of host
program cell death and
defense response
Table: 1. Plant genes and the pathogen molecules they interact with to confer susceptibility to necrotrophic pathogens
Faris and Friesen, 2020
6
7. 7Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
Classical gene for gene model v/s Inverse gene for gene model
Classical gene for gene Model
• Biotrophic plant–pathogen
interactions.
• The direct and indirect interaction
between the host (R) and pathogen
(Avr) components leads to disease
resistance. (effector-triggered
immunity).
• Incompatible interaction between Avr
and R= Resistance reaction.
Inverse gene for gene model
• Necrotrophic plant-pathogen
interaction
• The direct and indirect interaction
between the host (S) and pathogen
(NE) components leads to disease
susceptibility. (effector-triggered
susceptibility).
• Compatible interaction between S and
NE= susceptable reaction.
Friesen and Faris, 2010
8. 8Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
T-Toxin : by Race T isolates of Cochliobolus heterostrophus (southern corn leaf
blight (SCLB) in maize).
T-toxin binds to the URF13 product of the T-urf13 gene which were assembled in the
cms-T mitochondrial plasma membrane of maize plant.
Pore formation and permeabilization of the inner mitochondrial membrane, which then
lead to effectively inhibiting malate dehydrogenase activity of infected host plant.
1. T-urf13-T-Toxin
Faris and Friesen, 2020
9. 9Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
2. LOV1-victorin
Victorin: produced by Cochliobolus victoriae (Victoria blight of oats).
Sensitivity to victorin is conferred by a single dominant gene in oat called Vb.
The Vb locus is thought to be the same locus as Pc-2, which confers resistance to oat
crown rust caused by Puccinia coronata f. sp. avenae.
In Arabidopsis by cloning Vb gene identified the victorin sensitivity gene: Locus
Orchestrating Victorin effects 1 (LOV1),
LOV1 is a member of the RPP8 family of proteins ( R gene): induction of the
pathogenicity gene PR-1 and the production of camalexin (disease resistance).
LOV1 : which encodes a coiled-coil, nucleotide binding, leucine-rich repeat (NLR)
protein.
LOV1 does not bind victorin directly but instead acts as a guard of the thioredoxin
TRX-h5 which is targeted for direct binding by victorin. LOV1 “guards” the defense
thioredoxin, TRX-h5 (guardee). Sweat and Wolpert, 2007
10. 10Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
PC-toxin (peritoxins): Produced by Periconia circinata cause milo disease in
sorghum.
PC-toxin sensitivity is conferred by Pc.
Compatible Pc–PC-toxin interactions lead to hallmarks of programmed cell death and
defense including inhibition of mitosis, condensed chromatin, electrolyte leakage,
potassium ion flux, and other disruption in cell development and function reminiscent
of a defense response.
3. Pc–PC-toxin
Faris and Friesen, 2020
11. 11Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
ToxA: First proteinaceous HST to be discovered in any pathosystem and was first
identified and purified from the tan spot fungus, Pyrenophora tritici-repentis: Ptr
ToxA.
ToxA gene transferred from Parastagonospora nodorum (SnToxA) (septoria nodorum
blotch (SNB) in wheat) to P. tritici-repentis by Lateral gene transfer mechanism.
ToxA gene was also identified in isolates of Bipolaris sorokiniana (spot blotch in
wheat).
NE behaviour of ToxA is conferred by Tsn1.
Tsn1: encodes a protein with serine/threonine protein kinase (PK) and NLR domains
all in the same open reading frame.
4. Tsn1–ToxA
Faris and Friesen, 2020
12. 12Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
ToxA does not interact directly with the Tsn1 protein.
ToxA interact chloroplast-localized protein called ToxABP1, plastocyanin and
pathogenesis-related protein 1 (PR-1).
The expression of Tsn1 is regulated by light.
In P. nodorum pathogen produced more number of HST genes viz., SnToxA, SnTox1,
SnTox2, SnTox3 and SnTox4.
Toxin Host gene Markers Maximum disease
significance
Host gene
chromosome
arm location
Reference
SnToxA Tsn1 Xfcp1, Xfcp2, Xfcp394,
Xfcp620
95% 5BL Friesen et al. (2006)
Liu et al. (2006)
Friesen et al. (2009)
Zhang et al. (2009)
Faris and Friesen (2009)
SnTox1 Snn1 Xfcp618, Xpsp3000 58% 1BS Liu et al. (2004a),
Liu et al. (2004b),
Reddy et al. (2008)
SnTox2 Snn2 XTC253803, Xcfd51 47% 2DS Friesen et al. (2007),
Friesen et al. (2009),
Zhang et al. (2009)
SnTox3 Snn3 Xcfd20 18% 5BS Friesen et al. (2007),
Liu et al. (2009)
SnTox4 Snn4 XBG26267, XBG262975,
Xcfd58
41% 1AS Abeysekara et al. (2009)
Friesen and Faris, 2010
Table 2: Stagonospora nodorum produced different HST and their respective host (wheat) gene.
13. Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
• First HST–host interaction to be described in the wheat–SNB system.
• Sensitivity to SnTox1 is conferred by the wheat gene Snn1.
• Snn1: member of the wall-associated kinase (WAK) class of receptor kinase genes.
• Snn1 domains: membrane-spanning proteins with intra-cellular protein kinase domains
and extracellular galac-turonan binding (GUB_WAK) and epidermal growth factor-
calcium binding (EGF_CA) domains.
• SnToxA–Tsn1, SnTox1–Snn1, SnTox2–Snn2 and SnTox4–Snn4 : all four interactions
were light dependent.
5. Snn1–SnTox1
Faris and Friesen, 2020
13
14. 14Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
McDonald and Solomon, 2018Faris and Friesen, 2020
15. 15Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
Map-based cloning of the Tsn1 gene.
Chromosome Walking and Identification of Tsn1 Candidate Genes.
Validation and Structural Characterization of Tsn1.
Comparative Analysis of Tsn1 candidate genes.
Transcriptional regulation of Tsn1 gene.
Type of ToxA-Tsn1 Protein Interaction.
Faris et al., 2010
Case study-1
16. 16Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
Map-based cloning of the Tsn1 gene
Fig. 1: A) Genomic region of Tsn1 gene(red); B)Genetic linkage map of the Tsn1 region on 5B-L chromosome of
wheat; C) BAC-based physical maps of the Tsn1 region anchored to the genetic map; D) Predicted candidate genes
(oval shape) and markers (names beginning with an “X”); E) Exons (purple) and UTRs (gray) of Tsn1 gene.
17. 17Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
Amplification of full length c-DNA Tsn1 by using primers located at the 5′ end of the
translation start site and the 3′ end of the stop codon of LDN (Langdon): to verify that the
S/TPK and NBS-LRR domains are encoded by a single transcript.
Validation and Structural Characterization of Tsn1
10,581 bp
4,473 bp
161bp 391 bp
: Exons : UTR
Fig. 3: Southern hybridization (Restriction enzyme: Xbal and Probed: FCG34 (NBS
region of Tsn1) and PCR analysis (primers for marker Xfcp623(Tsn1) (intron five of
Tsn1) of 24 selected wheat lines.
Fig. 2: Structural characterization of Tsn1 region of LDN
Table. 3: Description of induced and natural mutations identified with the Tsn1 gene
Fig. 3: Leaves of Kulm (Tsn1) (A and C) and Kems103 (Tsn1 mutant) (B and D)
inoculated with S. nodorum (A and B) and infiltrated with ToxA (C and D).
18. 18Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
Fig. 4: A) Colinearity of genes within the Tsn1 region; B) Comparisons of the Tsn1 domains
• At the amino acid level,
the S/TPK and NBS-LRR
portions of Tsn1 are most
similar to rice homologs
• The separate S/TPK and
NBS domain of Tsn1 is
closely related to R gene
of barley stem rust: Rpg1
and maize rust: Rp3.
19. 19Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
Transcriptional Regulation of Tsn1
Fig. 5: Tsn1 expression
survey by RT-PCR with
GAPDH as an endogenous
control
Fig. 7: RQ-PCR evaluation of Tsn1 expression in ToxA-challenged plants
Interaction of Tsn1 Protein with ToxA
Yeast two-hybrid analysis
Negative results observed between the full-length Tsn1 gene and individual S/TPK,
NBS, and LRR domains with ToxA.
Tsn1 protein does not interact directly with ToxA
Fig. 6: Quantitative evaluation of Tsn1 gene expression by using RQ-PCR
20. 20Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
SnToxA: Parastagonospora nodorum
+
Necrotrophic sensitivity gene: Snn1
Shi et al., 2016
Case study- 2
Septoria nodal blotch
21. 21Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
Fig. 8: A) The genomic region of Snn1 gene on the short arm of 1B chromosome (red); B) Genetic linkage map of the
Snn1 region; C) BAC based physical map of the Snn1 region anchored to the genetic linkage map; D) Genetic linkage
mapping of the seven candidate genes identified in the four BACs from the candidate gene region in (C).
Fig. 9: Gene structure of the TaWAK (Snn1) gene
: Exon; : Introns
Map-based cloning of the Snn1 gene.
22. 22Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
Validation of Snn1 by mutagenesis and transgenesis
Ethylmethane sulfonate (EMS) treatment : Seeds of the SnTox1-sensitive wheat landrace Chinese spring
(CS)
Fig. 10: Infiltration and inoculation reactions on leaves of wild-
type CS and the EMS mutant CSems6125
Fig. 11: C) Reactions to SnTox1 infiltrations of CS (Snn1+), untransformed
Bobwhite (BW; Snn1−), and sensitive and insensitive T1 transgenic plants both
derived from the same event (BW5240). D) Transgenic plants that were sensitive
to SnTox1 were also susceptible to disease caused by spores of an SnTox1-
producing fungal isolate
Fig. 12: E)All SnTox1-sensitive T1 plants derived from event BW5240 had
the TaWAK transgene, and all insensitive plants lacked the transgene.
F) Similarly, all SnTox1-sensitive BW5240 T1 plants expressed TaWAK,
whereas the insensitive plants did not
23. 23Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
Transcriptional regulation of Snn1
Fig. 13: Snn1 expression survey in CS by RT-PCR with GAPDH as an endogenous control
Fig. 14: Quantitative expression of Snn1 by RQPCR B) 2-week-old plants exposure to 12-hour light/dark cycle; C) SnTox1-challenged plants
24. 24Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
Yeast two-hybrid analysis of Snn1-SnTox1 interactions
Fig. 15: Overview of the Snn1-SnTox1 and Tsn1-SnToxA interactions
26. Few Reports of plant resistance gene hijacked by necrotrophic pathogens
27. 27Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
Difference in the life cycle behavior of Necrotrophic fungi: induce ETS by hijacking
the host resistance gene.
Abolish NE recognition.
Elimination of NE sensitivity genes is a full of potential risks. Eg: Vb/Pc-2 genes in
oat, it is possible that a gene conferring susceptibility to a necrotroph could potentially
confer resistance to a biotroph.
Selection pressure on the pathogen to identify and subvert new host targets.
28. 28Plant genes hijacked by necrotrophic fungal pathogens , 11580; 2019-2020, IARI, New Delhi
Future aspects…….
Necrotrophic specialists harbor the ability to exploit diverse host targets to
hijack the host defense mechanisms and cause disease.
Identities of the NE sensitivity genes in other systems and understand the
extent at which to subvert additional genes/pathways to cause disease.
Editor's Notes
(co-immunoprecipitation. )
Therefore, SnTox1 does not enter the plant cell but interacts directly with the extracellular domain of the Snn1 protein.
durum wheat cultivar Langdon (LDN). Markers used for association mapping of the 386 Triticum accessions are indicated in blue. The blue and red
lines indicate the candidate gene regions as defined by recombination in the mapping population and association mapping of the 386 Triticum accessions,
respectively.
chromosome
walking was conducted to assemble a physical map spanning the
Tsn1 locus. hypothetical
protein, a potassium transporter, a U2 small nuclear (sn)
ribonucleoprotein (RNP) auxiliary factor, and, potentially, a single
gene encoding S/TPK-NBS-LRR domains
not appear to contain a coiled-coil domain. In addition,the gene does not contain any apparent transmembranedomains, and is therefore likely located in the cytoplasm
The results of this work, along with a growing amount of evidence
indicating that common signaling pathways are associated
with both biotroph resistance and necrotroph susceptibility (19,
27), suggest that host response mechanisms associated with ETS
to necrotrophs and ETI to other pathogens are very similar. The
differences in the outcomes may be attributed to the biology of
the pathogen (i.e., necrotrophs are equipped to thrive in environments
that would be detrimental to pathogens with biotrophic
lifestyles).
The results of this work, along with a growing amount of evidence
indicating that common signaling pathways are associated
with both biotroph resistance and necrotroph susceptibility (19,
27), suggest that host response mechanisms associated with ETS
to necrotrophs and ETI to other pathogens are very similar. The
differences in the outcomes may be attributed to the biology of
the pathogen (i.e., necrotrophs are equipped to thrive in environments
that would be detrimental to pathogens with biotrophic
lifestyles).
The green oval represents TaWAK, which cosegregated with Snn1. linkage map showed that only one of them cosegregated with
Snn1, and the other six candidates were separated from Snn1 by recombination
Events. 2A). The deduced amino acid sequence indicated that
the protein contains conserved wall-associated receptor kinase galacturonan
binding (GUB_WAK), epidermal growth factor–calcium
binding (EGF_CA), transmembrane, and serine/threonine protein kinase
(S/TPK) domains (Fig. 2A), with the S/TPK domain predicted to
be intracellular and the GUB_
To further validate the TaWAK gene as Snn1, we transformed the
SnTox1-insensitive wheat genotype BW with the full-length TaWAK
cDNA driven by the maize ubiquitin promoter TaWAK-possessing transgenic plants were
also susceptible to SNB The mutagenesis and transgenesis experiments together demonstrated
that the TaWAK gene was both sufficient and necessary to
confer sensitivity to SnTox1 and susceptibility to SnTox1-producing
isolates of P. nodorum. Therefore, this provided conclusive evidence
that TaWAK was indeed the Snn1 gene
Evaluation of Snn1 transcriptional expression in different plant tissues
of CS. nn1 expression in SnTox1-infiltrated
plants increased to about 62% of the level of the control plants at 24 hours
after infiltration and to less than half the level of control plants at 48 hours.
This indicated that Snn1 is not induced or up-regulated by SnTox1 but is,
instead, down-regulated over time.
The Snn1 and SnTox1 proteins interacted directly in yeast. Snn1 and SnTox1 were expressed in yeast as the prey and the bait proteins, respectively. The results indicated that the SnTox1 protein likely interacts directly with Snn1 within a region of 140–amino acid residues between the extracellular GUB_WAK and EGF_CA domains.