plant pathogen interaction
different types of pathogens
gene for gene hypothesis
direct receptor model
Elicitor receptor model
suppersor repressor model
gaurd hypothesis
Plant - Pathogen Interaction and Disease DevelopmentKK CHANDEL
Plant diseases are the result of infection by any living organisms that adversely affect the growth, development, physiological functioning and productivity of a plant, manifesting outwardly as visible symptoms.
Plant - Pathogen Interaction and Disease DevelopmentKK CHANDEL
Plant diseases are the result of infection by any living organisms that adversely affect the growth, development, physiological functioning and productivity of a plant, manifesting outwardly as visible symptoms.
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.
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.”
Plant viruses are transmitted from plant to plant in a number of ways.
Transmission of viruses by vegetative propagation.
Mechanical transmission of viruses through sap.
Transmission of viruses by seed.
Transmission of viruses by Pollen.
Transmission of viruses by dodder.
Transmission by vectors.
Effect of environment and nutrition on plant disease developmentparnavi kadam
BRIEF AND PRECISE POINTS ON PLANT DISEASE DEVELOPMENT. IT MOSTLY FOCUSES ON HOW THE FACTORS AFFECT THE MICROBES AND THEN THEIR MICROBIAL EFFECT ON DISEASE DEVELOPMENT.
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.
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.”
Plant viruses are transmitted from plant to plant in a number of ways.
Transmission of viruses by vegetative propagation.
Mechanical transmission of viruses through sap.
Transmission of viruses by seed.
Transmission of viruses by Pollen.
Transmission of viruses by dodder.
Transmission by vectors.
Effect of environment and nutrition on plant disease developmentparnavi kadam
BRIEF AND PRECISE POINTS ON PLANT DISEASE DEVELOPMENT. IT MOSTLY FOCUSES ON HOW THE FACTORS AFFECT THE MICROBES AND THEN THEIR MICROBIAL EFFECT ON DISEASE DEVELOPMENT.
Plant Pathogen Interaction -
Plants and pathogens continually compete for supremacy as they coevolve. In nature, many plants are resistant to most pathogens, but some pathogenic microbes are capable of causing severe diseases. The primary barrier of plants against pathogenic invasion is the preformed defense layer, including the plant cell wall and pre-produced metabolites. To successfully respond to and defend against pathogenic microbes, plants developed multi-layered protective and surveillance networks. The first layer of the plant immune system is PAMP-triggered immunity (PTI), which is activated by pathogen-associated molecular patterns (PAMPs), the conserved molecular structures of pathogens. When the first layer of the immune response—is no longer effective as a result the pathogenic effectors, effector-triggered immunity (ETI) often provides resistance. In ETI, host plants directly or indirectly perceive pathogen effectors via resistance proteins and launch a more robust and rapid defense response. Resistance proteins are typically found in the form of nucleotide binding and leucine-rich-repeat-containing receptors (NLRs).
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.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
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2. HOST-PATHOGEN INTERACTION
Disease is a disfunction of normal
physiological processes in plants
caused by microorganisms or an
abiotic factor.
• A pathogen that causes
diseases is termed virulent
• A pathogen that does not
cause diseases is termed
avirulent
Types of pathogen based on
effects:
• necrotrophy: plant cells are
killed
• biotrophy: plant cells remain
alive
• hemibiotrophy:plant cells
initially alive and killed later
3. Types of pathogen based on effects:
• Necrotrophy: plant cells are killed
• Biotrophy: plant cells remain alive
• Hemibiotrophy:plant cells initially alive and
killed later
4.
5. Types of Pathogens
• Bacteria: Enter through wounds or stomata, live
between plant cells.
• Fungi: filamentous growth with specialized
structures for penetration, feeding in cells. Can
penetrate directly into plant and move
intercellularly or through cells.
• Viruses: Nucleic acid (+ RNA mostly) encapsulated
in a protein coat-Spread by plasmodesmata.
6. Classes of plant immune
responses
• Basal response: transcription of genes in
response to PAMP recognition.
• Hypersensitive response (HR); apoptosis of cells
at the site of infection
• Systemic acquired immunity: The entire plant
becomes resistant to infection
• Jasmonic acid/ethylene pathway: The entire
plant and neighboring plants develop resistance
to herbivores.
• Non-host immunity
7. INDUCED DEFENCE
Induced defence
Programmed cell death
(PCD)
Induced structural barriers
phytoalexins
Pathogenesis related
proteins (PR-proteins)
Post transcriptional gene
silencing (PTGS)
Heil, M., and R.M. Bostock. 2002
8. STEPS IN PLANT-PATHOGEN
INTERACTION
RECOGNITION-depends on generation of
elicitors by the pathogen (Diseases/Non Diseses)
TRANSDUCTION: Signal transduction at the
cellular level refers to the movement of signals.
1. PERCEPTION : is a surface level phenomena in
which elicitor from the pathogen are recognized by
host receptor.
2. SIGNALLING
3. RESPONSE
9.
10. PERCEPTION
• Perception means how pathogen and host recoginize
each other. It may take place directly or indirectly.
• After evaluation of numerous physiological,
biochemical and genetic experiments, different
models have gained importance as the basis for all
models is the gene-for-gene relationship between
host and pathogen for triggering race-specific
resistance.
• –Direct interaction models
• –Indirect interaction models
11. GENE FOR GENE HYPOTHESIS
• Flor (1946,47) showed correlation between
inheritance of pathogenicity and resistance
to linseed rust caused by Melampsora lini
which is now commonly known as gene -for
-gene hypothesis.
• that “for each gene conditioning rust
reaction in the host there is a specific gene
conditioning pathogenicity in the parasite.
• Gene for gene hypothesis does not address
the actual nature of the process, structure
and substances participating in the signal
transduction.
12. DIRECT INTERACTION MODELS
• four models have been proposed to demonstrate the
nature of recognition reaction and the expression of
the defense reaction:
• –The Elicitor- Receptor model
• –The Dimer Model
• –The Ion Channel defense model
• –The Suppressor- receptor model.
13. Elicitor-Receptor Model
(Albersheim et al., 1981)
• This hypothesis involve the two gene group system of
plant genes,
• where one gene act as a sensor within the signal-sensor
reaction that help in pathogen recognition
• Second group of several genes that express the plant
defense reactions
• However, this model does not explain how the
recognition by the plant turns on expression of the plant
dense genes.
14. • Drawbacks: the elicitor receptor model specifies
neither the structure of the corresponding
receptor nor does it define the nature and
mechanism of action of the effectors.
15. SUPRESSOR RECEPTOR MODEL
• Model was extended by Bushnell and Rowell (1981) and Heath
(1982).
• •It is based on the fact that all plants are susceptible to attack of any
pathogen and hence plant exhibit basic compatibility. However,
basic compatibility is conteracted by a general elicitor produced by
all pathogen which releases unspecific basic resistance.
• •In order to colonize a particular plant the homologous pathogen
has to produce specific suppressor to block the action of general
elicitor i.e. pathogen blocks secondarily its own elicitor of basic
resistance.
• •It assumes that active basic resistance is triggered unspecifically by
general acting elicitors produced by all pathogens is like wise
recognized by receptors present in all plants.
16.
17. • However, part pathogen become compatible with certain
plant species because of mutation, the pathogen produces
a species specific suppressor that prevents its general
elicitor from acting on plant receptor or block elicitor
receptor interaction in other way, disturbing subsequent
signal transduction, or hindering formation or action of
effector.
• •In short, basic resistance would be prevented by specific
suppressor produced by pathogens thus allowing basic
compatibility
• –thus Bailey described this as elicitor/specific
suppression, to counteract to the release of active basic
resistance by a specifically acting elicitor.
18. INDIRECT MODELS OF INTERACTIONS
• Lack of evidence for a direct interaction indicated the
involvement of some other type of interaction
between the R gene and Avr gene products and this
lead to the concept of indirect interaction models
leading to resistance.
• lack of evidence for a direct interaction indicated the
involvement of some other type of interaction
between the R gene and Avr gene products and led to
the formation of the guard hypothesis.
19. GUARD HYPOTHESIS Vander
Biezen and Jones, 1998
• This model proposes that the R proteins interact, or
guard, a protein known as the guardee, which is the
target of the Avr protein. When it detects interference
with the guardee protein, it activates resistance.
• No direct interaction is found between Avr factor and
R proteins except shown in Avr pto-pto and Avr pita-
pita
20.
21. • Arabidopsis RPM1 is a peripheral plasma membrane
NB-LRR protein. It is activated by either the AvrRpm1 or
the AvrB effector proteins. AvrRpm1 enhances the
virulence of some P. syringae strains on Arabidopsis as
does AvrB on soybeans. AvrRpm1 and AvrB are
modified by eukaryote-specific acylation once delivered
into the cell by the type III secretion system (red syringe)
and are thus targeted to the plasma membrane. The
biochemical functions of AvrRpm1 and AvrB are
unknown, although they target RIN4, which becomes
phosphorylated (1P), and activate RPM1. In the absence
of RPM1, AvrRpm1 and AvrB presumably act on RIN4
and other targets to contribute to virulence.
22. CONCLUSION
The interaction between plant and pathogen are
specific, complex and dynamic.
Signals for activation of various defenses initiate in
response to recognition.
The outcome of interaction dependent on initial
sensing of the other organism via exchange of
molecular signal through signaling cascade and
modified gene expression.
Recognition is the first step by which response is
generated which is involved in defense signal
transduction.