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.
Plants have array of defense response against biotic stresses which could be either structural reinforcement, release of chemicals, and defense gene expression against invading organisms. The physical barriers are trichoms, waxy cuticle, thick cell wall. Once the pathogen overcomes the first line of defense, basal or innate defense response comes into play. Pathogens secrete some conserved molecules known as Pathogen Associated Molecular Pattern (PAMP/MAMP), which are recognized by transmembrane receptors present in the plasma membrane and initiate a series of signal cascade reaction which ultimately leads to activation of various defense related genes. Apart from inducing the expression of defense related genes, it also triggers a hypersensitive reaction (HR) which cause deliberate cell death at the site of infection and limit the pathogen access to water and nutrient by sacrificing a few cells in order to save the rest of the plant. Once HR is triggered, plant tissue may become highly resistant to a broad range of pathogens for an extended period of time. This phenomenon is called Systemic Acquired Resistance (SAR).
Plants respond to herbivory is a similar manner as described above. The biochemical mechanisms of defense against the herbivores are wide-ranging, highly dynamic, and are mediated both by direct and indirect defenses. The defensive compounds are either produced constitutively or in response to plant damage, and affect feeding, growth, and survival of herbivores. In addition, plants also release volatile organic compounds that attract the natural enemies of the herbivores. These strategies either act independently or in conjunction with each other. However, our understanding of these defensive mechanisms is still limited. Induced resistance could be exploited as an important tool for the pest management to minimize the amounts of insecticides used for pest control. Host plant resistance to insects, particularly, induced resistance, can also be manipulated with the use of chemical elicitors of secondary metabolites, which confer resistance to insects. By understanding the mechanisms of induced resistance, we can predict the herbivores that are likely to be affected by inducing responses. The elicitors of induced responses can be sprayed on crop plants to build up the natural defense system against damage caused by herbivores. The induced responses can also be genetically engineered, so that the defensive compounds are constitutively produced in plants challenged by the herbivory. Induced resistance can be exploited for developing crop cultivars, which readily produce the inducible response upon mild infestation, and can act as one of components of integrated pest management for sustainable crop production.
Gene for gene system in plant fungus interactionVinod Upadhyay
MOLECULAR CHARACTERIZATION OF GENE FOR GENE SYSTEMS IN PLANT- FUNGUS INTERACTION AND THE APPLICATIONS OF AVIRULENCE GENES IN CONTROL OF PLANT PATHOGENS
Molecular basis of plant resistance and defense responses to pathogensSenthil Natesan
In response to pathogen attack, plants have evolved sophisticated defense mechanisms to delay or arrest pathogen growth.Unlike animals, plants lack a circulating immune system recognizing microbial pathogens. Plant cells are more autonomous in their defense mechanisms and rely on the innate immune capacity of each cell and systemic signals that disseminate from infection sites (Jones and Dangl, 2006). Plant innate immunity consists of preformed physical and chemical barriers (such as leaf hairs, rigid cell walls, pre-existing antimicrobial compounds) and induced defenses. Should an invading microbe successfully breach the pre-formed barriers, it may be recognized by the plant, resulting in the activation of cellular defense responses that stop or restrict further development of the invader.
Plants have array of defense response against biotic stresses which could be either structural reinforcement, release of chemicals, and defense gene expression against invading organisms. The physical barriers are trichoms, waxy cuticle, thick cell wall. Once the pathogen overcomes the first line of defense, basal or innate defense response comes into play. Pathogens secrete some conserved molecules known as Pathogen Associated Molecular Pattern (PAMP/MAMP), which are recognized by transmembrane receptors present in the plasma membrane and initiate a series of signal cascade reaction which ultimately leads to activation of various defense related genes. Apart from inducing the expression of defense related genes, it also triggers a hypersensitive reaction (HR) which cause deliberate cell death at the site of infection and limit the pathogen access to water and nutrient by sacrificing a few cells in order to save the rest of the plant. Once HR is triggered, plant tissue may become highly resistant to a broad range of pathogens for an extended period of time. This phenomenon is called Systemic Acquired Resistance (SAR).
Plants respond to herbivory is a similar manner as described above. The biochemical mechanisms of defense against the herbivores are wide-ranging, highly dynamic, and are mediated both by direct and indirect defenses. The defensive compounds are either produced constitutively or in response to plant damage, and affect feeding, growth, and survival of herbivores. In addition, plants also release volatile organic compounds that attract the natural enemies of the herbivores. These strategies either act independently or in conjunction with each other. However, our understanding of these defensive mechanisms is still limited. Induced resistance could be exploited as an important tool for the pest management to minimize the amounts of insecticides used for pest control. Host plant resistance to insects, particularly, induced resistance, can also be manipulated with the use of chemical elicitors of secondary metabolites, which confer resistance to insects. By understanding the mechanisms of induced resistance, we can predict the herbivores that are likely to be affected by inducing responses. The elicitors of induced responses can be sprayed on crop plants to build up the natural defense system against damage caused by herbivores. The induced responses can also be genetically engineered, so that the defensive compounds are constitutively produced in plants challenged by the herbivory. Induced resistance can be exploited for developing crop cultivars, which readily produce the inducible response upon mild infestation, and can act as one of components of integrated pest management for sustainable crop production.
Gene for gene system in plant fungus interactionVinod Upadhyay
MOLECULAR CHARACTERIZATION OF GENE FOR GENE SYSTEMS IN PLANT- FUNGUS INTERACTION AND THE APPLICATIONS OF AVIRULENCE GENES IN CONTROL OF PLANT PATHOGENS
Molecular basis of plant resistance and defense responses to pathogensSenthil Natesan
In response to pathogen attack, plants have evolved sophisticated defense mechanisms to delay or arrest pathogen growth.Unlike animals, plants lack a circulating immune system recognizing microbial pathogens. Plant cells are more autonomous in their defense mechanisms and rely on the innate immune capacity of each cell and systemic signals that disseminate from infection sites (Jones and Dangl, 2006). Plant innate immunity consists of preformed physical and chemical barriers (such as leaf hairs, rigid cell walls, pre-existing antimicrobial compounds) and induced defenses. Should an invading microbe successfully breach the pre-formed barriers, it may be recognized by the plant, resulting in the activation of cellular defense responses that stop or restrict further development of the invader.
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.
Host-pathogen Interactions, Molecular Basis and Host Defense: Pathogen Detect...QIAGEN
Host–pathogen interactions are strikingly complex during infection. This slidedeck provides an overview of the molecular basis of these intricate interactions: the impact of microbiota on innate and adaptive immunity, metabolism, and insulin resistance and host defense mechanisms. Various research tools will be introduced to simplify and streamline each step of studying the host response, enabling detection of pathogens, analysis of gene expression and regulation, epigenetic modification, genotyping and signal transduction pathway activation.
The power point presentation includes information regarding various methods and concepts involved in fungi bacteria and virus with some suitable examples
Genetic and Molecular basis of Non-Host ResistanceAkankshaShukla85
Non-host resistance is a broad-spectrum plant defense that provides immunity to all members of a plant species against all isolates of a microorganism that is pathogenic to other plant species.
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.
Host-pathogen Interactions, Molecular Basis and Host Defense: Pathogen Detect...QIAGEN
Host–pathogen interactions are strikingly complex during infection. This slidedeck provides an overview of the molecular basis of these intricate interactions: the impact of microbiota on innate and adaptive immunity, metabolism, and insulin resistance and host defense mechanisms. Various research tools will be introduced to simplify and streamline each step of studying the host response, enabling detection of pathogens, analysis of gene expression and regulation, epigenetic modification, genotyping and signal transduction pathway activation.
The power point presentation includes information regarding various methods and concepts involved in fungi bacteria and virus with some suitable examples
Genetic and Molecular basis of Non-Host ResistanceAkankshaShukla85
Non-host resistance is a broad-spectrum plant defense that provides immunity to all members of a plant species against all isolates of a microorganism that is pathogenic to other plant species.
Plant disease resistance genes: current status and future directions.RonikaThakur
Agriculture plays a key role to ensure the food security. But plant diseases hinder the crop production by reducing yield to much extent. To overcome this problem it is crucial to understand plant disease resistance genes which prevent growth of plant pathogens thereby reducing the yield loss.
According to current human opinion and knowledge living organisms can be divided into seven kingdoms. The similarities and differences between these seven groups also the relationships between them are very interesting. These relationships lead to creation the different kinds of biological terms such as, mutualism, commensalism and parasitism. So plants and animal also microorganisms have to fight sometimes. The mechanisms of pathogenicity and the mechanisms of defense can be either similar or different. Emphasizing aspect of pathogenicity of some microorganisms, such as Salmonella, Fusarium and Tobacco mosaic virus can case to disease in plants and animals.
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
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.”
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
The ASGCT Annual Meeting was packed with exciting progress in the field advan...
Plant immunity towards an integrated view of plant pathogen interaction and its implication in plant breeding
1. “Plant immunity: towards anPlant immunity: towards an
integrated view of plant pathogenintegrated view of plant pathogen
interaction and its implication ininteraction and its implication in
plant breedingplant breeding”
1
Pavan. R
Department of Genetics and Plant Breeding
University of Agricultural Sciences
Bengaluru-65
6. “For each resistance gene in the host there is a
corresponding gene for avirulence in the
pathogen cnferring resistane and viceversa”
Host plant genotypePathogen
genotype R1 r2 r1 R2
Avr1, avr2 I
I
C
Cavr1, Avr2
I - incompatible - no disease
C - compatible - disease
Gene for gene hypothesis
H.H. Flor 6
7. It is a state of defense against infectious
pathogens
Pathogens are like Bacteria, Fungi, Virus,
Nematode, Oomycetes etc.
Mode of entry of pathogen depend on type of
pathogen
Bacteria – stomata, hydathodes and wounds
Nematode – Stylet
Fungi – Haustoria
What is plant immunity?
7
9. Forms of plant resistance
Antipathy- Lack of interest of pests or pathogens in a
plant. Ex- Resistance of Arabidopsis to insects -
Glucosinolate contents
Hindrance- Lack of pathogen’s ability to parasitize the
plant because of certain plants features
Ex-higher levels of calcium - macerating pathogens
through strengthening the cell walls
(Datnoff et al. 2007)
Defence- Based on the plant innate immune system
9
11. PAMP Triggered Immunity (PTI)
PAMP (Pathogen Associated Molecular Pattern)
The molecules of pathogens, conserved across larger
group of pathogens
Highly indispensable to the pathogens, required for
their survivality
These molecules do not exist in host
Ex. Flagellin, EF-Tu, lipid, chitin, protein molecules of
pathogens
11
12. • Plasma membrane-localized receptors that
recognize the presence of PAMP’s in the
extracellular environment.
• Located in plasma membrane
• Ex. FLS2, ERF, CEBiP, etc
PRR (Pattern recognition receptor)
12
13. ETS (Effector Triggered Susceptibility)ETS (Effector Triggered Susceptibility)
Effector are any regulatory molecules secreted
by pathogens
Modifies host protein to establish their growth
Effector perform three main functionsEffector perform three main functions
Structural role: Ex. Fungi, secret extra haustorial
molecule
Nutrient leakage: Ex. P. syringae HopM effector
protein
Pathogenicity: Ex. HopA1 dephosphorylates MAP
kinase results in inhibition of PTI 13
14. The plant defence response elicited by effector
recognition.
The effector molecules are recognized by R
protein
Four major classes of R genes
NB-LRR (nucleotide binding leucine rich repeat)
genes
Ser/Thr kinases
Receptor-like kinases (RLKs)
Receptor-like proteins (RLPs)
Effector triggered immunity (ETI)
14
18. Stomatal closure
Ion fluxes
Oxidative burst
Phyto-Hormone action
Induced systemic resistance
Systemic Acquired Resistance
18
Defence Mechanism of plant toward off
pathogens
19. 1. Stomatal closure1. Stomatal closure
Stomata are natural opening through pathogen can
easly enter into apoplast
Stomatal closure is part of a plant innate immune
response to restrict bacterial invasion.
19
20. Bacteria and PAMPs Trigger Stomatal Closure in Arabidopsis
20
Maeli etal, 2006
(1) Stomata actively
closes as an initial
response to
both plant and human
pathogenic bacteria,
(2) Pst DC3000 has
evolved a mechanism
to reopen stomata 3 hr
after incubation
(3) Inoculum
concentration 1x 107
cfu/ml 1hr-closure &
3hr-Reopen
21. Involvement of the FLS2 Receptor and Salicylic
Acid in PAMP Induced Stomatal Closure 21
flg22:
biologically
active peptide
derived from
flagellin
MES: Buffer
LPS:
Lipopolysaccha
rides
24. Model Depicting Bacterium- and PAMP-Induced Stomatal
Closure in the Arabidopsis Guard Cell
24
Subunit of E3
ubiquitin ligase
involved
JA signalling
25. 25
2. Ion fluxes
Membrane permeability changes rapidly leading to
a loss of cellular electrolytes such as K+
and an
uptake of H+
.
At the same time, there is often an influx of Ca2+,
a key intracellular signal in plants that is involved
in the activation of enzymes and gene expression.
The experimental blocking of Ca2+
transport across
membranes in inoculated bean cells also inhibits
gene activation and subsequent defence responses.
26. 26
3. Oxidative burst
It is a rapid, transient, production of huge
amounts of reactive oxygen species (ROS)
Produced from membrane localized NADPH
oxidase (Nuhse et al, 2007)
JA/SA pathway activated, finally PCD
27. 27
Abbreviations used : AC, adenylate cyclase ; CWP, cell-wall-bound peroxidase ;
E, elicitor; Er: receptor; G, GTP-binding protein(s); PLase A and PLase C,
phopholipases A and C; R, reductant.
Schematic representation of major hypotheses describing
the possible origin of ROS building the oxidative burst
29. • Rapid death of cells in the local region surrounding
an infection.
• Restrict the growth and spread of pathogens to other
parts of the plant.
• Favor growth of pathogens with a necrotrophic
lifestyle
5. Hypersensitive response
29
30. 30
Biotrophic: pathogens propagate in living plant tissue
and generally do not cause necrosis as a result of
infection.
Necrotrophic: pathogens actively induce necrosis in
infected tissues, often through the production of
toxins.
Hemibiotroph: An organism that is parasitic in living
tissue for some time and then continues to live in dead
tissue
31. It is secondary resistance response
Because, once plant defense responses are
activated at the site of infection, a systemic defense
response is triggered in distal plant parts to protect
these undamaged tissues against subsequent
invasion by the pathogen.
Long-lasting and broad-spectrum induced disease
resistance
Act non-specifically through out the plant and
reduce disease severity
6. Systemic Acquired Resistance(SAR)
31
32. 32
SAR signal is a generated with in 4hr of
inoculation
SA could be detected in phloem of leaf 8hr after
inoculation
Increased level of SA in phloem of leaf above
the incubated leaf
Expression of SAR occurs with in 24hr after
inoculation
34. 34
PR proteins (PRP)
Proteins produced in plants when it is attacked by
pathogen, they are antimicrobial/viral/ insecticidal
Its extremely acidic/ basic in nature, therefore it is
highly soluble an highly reactive.
Crosslink the molecules of cell wall and acts as
barricade by accumulation of lignin which helps the
cell wall to protrude as papillae.
Gives alarming signals to neighbouring cells
It present in both resistant and susceptible plant, but
concentration is differs. When there is infection its
concentration increases and viceversa.
35. 35
PR
proteins
Plants in which PRP
detected
Function
PR1 Rice, barley, maize,
tomato, tobacco
Plant cell wall thickening,
resistance to the spread of
the pathogen on the apoplast
PR 2 Rice, barley, maize,
tomato, tobacco,
potato, pepper, bean,
Brassica, sugar beet
β-1-3-glucanase
PR3 Rice, maize, tomato,
pepper, sugar beet,
rape seed
Chitinase
PR 4 Tomato, tobacco,
rubber tree
Chitinase
PR5 Rice, wheat, barley,
oats, tomato, tobacco,
potato
Alternation of fungal
memnrane
PR6 barley, tomato,
tobacco
Proteinase inhibitor
36. 36
PR
proteins
Plants in which PRP
detected
Function
PR8 Cucumber Chitinase
PR9 Tomato, rice, tobacco,
wheat
Peroxidase
PR10 Potato, asperagus,
pea, bean, rice
Ribonucleases
PR11 Tobacco Chitinase
PR12 Arabidopsis, pea, Defensin
PR13 Barley Thionin
PR14 Barley Lipid transfer proteins
PR15 Barley Germin like oxalate oxidase
PR16 Barley and wheat Germin like proteins without
oxalate oxidase
PR17 Wheat, barley, tobacco Peptidase
38. 38
1. Manipulating PAMP/MAMP receptors to induce immunity
PTI activation is based upon the recognition of
microbial surface structures (PAMPs/MAMPs), such
as bacterial flagellin, bacterial elongation factor EF-
Tu or fungal chitin.
For example, Arabidopsis FLS2 and EFR are plasma
membrane receptor kinases that sense flagellin or
EF-Tu through binding to their leucine-rich repeat
(LRR) ectodomains
40. 2. Pyramiding and Introgressing R gene
40
2003, PNAS
Late blight, caused by the oomycete pathogen
Phytophthora infestans, is the most devastating
potato disease in the world
The wild diploid potato species Solanum
bulbocastanumis highly resistant to all known
races of P. infestans
41. 41
Cloning of the major resistance gene RB in S.
bulbocastanum by using a map-based approach in
combination with a long-range (LR)-PCR strategy.
A cluster of four resistance genes of the CC-NBSLRR
(coiled coil–nucleotide binding site–Leu-rich repeat)
class was found within the genetically mapped RB
region.
Transgenic plants containing a LR-PCR product of
one of these four genes displayed broad spectrum
late blight resistance.
43. Genetic and physical maps of the genomic region
43
BAC clones from the RB haplotype (filled boxes) and BAC clones
from the rb haplotype (open boxes). Both 177O13 and CB3A14
contain one truncated and four complete RGAs. The direction of
transcription of each gene(an arrow). The 3.6-kb deletion region
between RGA2 and RGA-tris marked.
44. 44
Late blight screening of transgenic
plants by using isolate US930287
Plants were scored as resistant (R) if the resistance score was >7.0 (< 25%
infection) and plants were scored as susceptible was <6.9 (>25% infection).
† Of the 14 resistant plants, nine plants had a score of 7 and five plants had a
score of 8.
45. Complementation analysis of putative RB genes
45
(A–C) Transgenic Katahdin plants- RGA1-PCR,RGA2-PCR, and RGA4-PCR,
respectively. (D) Control Katahdin plant. (E) Katahdin plant that was not inoculated.
(F–I) Transgenic Katahdin plants containing constructs RGA1-BAC, RGA2-
BAC,RGA3-BAC, andRGA4-BAC, respectively.
47. Disadvantage of R genes …….?
Ectopic expression of R genes can
sometimes activate defence pathways in the
absence of pathogen
Reduced crop yields
Reduced Fitness
47
48. 3. Antifungal fusion proteins to induce immunity
48
Fusarium head blight (FHB) or scab of wheat is a
devastating disease in warm and humid regions at
wheat-flowering periods worldwide.
Expression of pathogen-specific antibodies in plants
has been proposed as a strategy for crop protection.
49. 49
An antibody fusion protein comprising a Fusarium-
specific recombinant antibody derived from chicken
and an antifungal peptide from Aspergillus giganteus
was expressed in wheat as a method for protecting
plants against FHB pathogens.
Plants expressing the antibody fusion displayed a
very significantly enhanced resistance in T2 and T3
generations upon single-floret inoculation with the
macroconidia of Fusarium asiaticum, the
predominant species causing FHB in China, indicating
a type II resistance.
50. Structure of AG-D2 fusion construct
50
An antifungal peptide sequence from Aspergillus giganteus (AG)
and a single-chain Fv (scFv) antibody coding region from
chicken.
Connected by a sequence encoding a 10-amino-acid glycine-
serine linker.
The AG-scFv fusion construct was inserted into the plant
expression vector pAHC25 using EcoRI and SacI sites.
Ubi-Pro, maize ubiquitin promoter; UT: 5′ untranslated region
of the petunia chalcone synthase gene; LP, leader peptide
sequence; c-myc, c-myc epitope tag; His6, histidine 6 tag; Nos-
T-Nos terminator.
51. 51
Integration and expression of AG-scFv fusion
gene in transgenic wheat.
A, T3 transgenic wheat lines 2,
and To detect the presence of
the AG-scFv fusion gene with
primers AGP1 and scFvP2.
B, RNA extracted from leaves of
the plants in A was used in a
RT- PCR assay to analyze
expression of the AG-scFvfusion
gene with the same set of
primers in A.
C, Proteins extracted from
leaves in A were fractionated by
electrophoresis on a 12% SDS-
PAGE and then subjected to
immunoblot analysis with an
antibody against the Histidine 6
tag
54. 54
Comparison of yield parameters between
nontransgenic plants and transgenic plants
expressing the antibody fusion.
A: Single floret inoculation and B: Spray inoculation
55. 55
FHB-susceptible cv.
Bobwhite,
FHB-resistant cv. Sumai3 at
21 days postinoculation with
the conidia of Fusarium
asiaticum.
A, Spikes of a single floret
(indicated by an arrow)
inoculated with the conidia
of F. asiaticum.
B, Spikes by spray
inoculation with the conidia
of F. asiaticum.
C, Grains from a spike of a
single-floret inoculation in A.
Phenotype of representative spikes and grains from T3
transgenic wheat line 2,
56. Phytoalexins are antimicrobial and often antioxidative
substances synthesized de novo by plants that accumulate
rapidly at areas of pathogen infection
They are broad spectrum inhibitors and are chemically
diverse with plant species.
Phytoalexins tend to fall into several classes including
terpenoids, glycosteroids and alkaloids
4. Use of phytoalexins to induce immunity
56
57. 57
1997
Stilbene synthase occurs in several plant species and
synthesizes the stilbene phytoalexin transresveratrol
Transfer of two genes from grapevine (Vitis Šinifera)
coding for stilbene synthase genes (vst1 and vst2 ) to
tomato by means of Agrobacterium tumefaciens
58. 58
The accumulation of the phytoalexin trans-
resveratrol, the product of stilbene synthase, for
resistance tomato to Phytophthora infestans (Late
blight of tomato).
Accumulation of resveratrol occurred after
inoculation with Botrytis cinerea (Gray mould in
tomato) and Alternaria solani (Early blight in
tomato)
59. Southern blot analysis of transgenic
tomato plants of the T 3 progeny
59
Southern blot analysis of transgenic tomato plants of the T3
progeny from regenerant To25 (lane 1±4), To42 (lane 5±8), and
transgenic oilseed rape as a positive control (lane c). Genomic DNA
was isolated from leaves and digested with EcoRI that generates
two fragments of 3.4 kb and 4.9 kb representing the two
transferred stilbene synthase genes.
60. 60
Northern blot analysis showing the transient
accumulation of stilbene synthase mRNA in leaves
Northern blot analysis showing the transient accumulation
of stilbene synthase mRNA in leaves of a transgenic tomato
plant of the T3 progeny from To25 after inoculation with
P.infestans. No specific mRNA was detectable immediately
after inoculation.*Leaves were treated with tap water only.
61. Resveratrol (stilbenoid, a type of natural phenol, and a
phytoalexin) accumulation in leaves of a transgenic
tomato plant from the T2 progeny of regenerant To25
after inoculation with P. infestans and B. cinerea.
61
62. Resveratrol contents of leaves of transgenic tomato plants
from T3 progeny of To25 4 days after inoculation with B.
cinerea, A. solani, and P. infestans
62
63. Disease symptoms on
leaves of a transgenic
tomato plant from the T3
progeny of To25
(right) and non-
transformed tomato plant
(left) 4 days (upper) and 6
days (lower) after
inoculation with P.
infestans.
63
64. Biological testing of transgenic tomato plants from progenies T2,
T3, and T4 of regenerant To25 and To42 for an increased
resistance to A. solani, B. cinerea, and P. infestans 4 days after
inoculation
64
65. Development of P. infestans on transgenic tomato plant
To25 (T 3 progeny) and non-transformed plant 6 days after
inoculation
65
66. Incidence of P. infestans on transgenic tomato
plants and non-transformed plants in
dependence on the leaf insertion
66
67. Probenazole (PBZ) is the active ingredient
of Oryzemate
Protection of rice plants from Magnaporthe
grisea (blast fungus)
PBZ pre-treatment increased accumulation
of SA and PR proteins in the eighth leaves
of adult plants
Takayoshi Iwai., et al 2008
67
5. Use of chemicals to induce immunity
68. Phenotypes of blast fungus-inoculated leaves of young and adult rice
plants. 68
69. Free SA and SAG levels in rice leaves after fungus inoculation and PBZ
treatment. 69
73. 6. RNAi-mediated silencing of pathogen’s
genes
Parasitism genes expressed in esophageal gland
cells mediate infection and parasitism of plants by
root-knot nematodes (RKN).
Parasitism gene 16D10 encodes a conserved RKN
secretory peptide
Used in vitro and in vivo RNA interference to induce
immunity
73
74. In Vitro RNAi of 16D10.
RNAi silencing of 16D10 in preparasitic M. incognita J2.
Fluorescence
microscopy
showing ingestion
of FITC in the
treated J2.
74
75. In Vivo RNAi of 16D10.
Overexpression of 16D10 dsRNA in Arabidopsis. 75