Plants mechanism against fungal pathogens through various biochemicals and .metabolic reactions.

1. Credit Seminar
MBB 591 (0+1)
On
Defence Mechanism In Plants Against Fungal Pathogen
Submitted to
Dr. Sushma Nema
Assistant Professor & Seminar
In-charge
Advisor
Dr. Keerti Tantwai
Assistant Professor
Biotechnology Centre
Submitted By
Prashant Gigaulia
ID No: 170117007
M.Sc.(Ag) Molecular Biology and Biotechnology
Biotechnology Centre
Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur

2.  As like other organism defence system, plant also have
defence mechanism against pathogens.
 Plants have a complex defense system against diverse
pathogens.
 Once pathogens overcome mechanical barriers to
infection, plant receptors initiate signaling pathways
driving the expression of defense response genes.
 Plant immune systems rely on their ability to recognize
enemy molecules, carry out signal transduction, and
respond defensively through pathways involving many
genes and their products.
INTRODUCTION

3.  The plant immunity community adopted the
nomenclature from animal innate immunity that was
proposed by Medzhitov and Janeway in the nineties of
the last century.
 The genetic basis of plant resistance was first elucidated
by Flor in the early 1940s (Flor, 1955).
 The theory of gene-for-gene complementarity between
host and pathogen (Keen, 1990).
Historical Aspects

4. A plant disease is usually defined as abnormal growth and/or
dysfunction of a plant. Diseases are the result of some
disturbance in the normal life process of the plant.
 Spores are the main dispersal mechanism
of fungi and can remain dormant until
germination conditions are appropriate.
 When a spore comes into contact with a
susceptible plant, it will germinate and
enter the host if the proper environmental
conditions are present.
 Hyphae develop from the germinated
spore and begin to extract nutrients from
host plant cells.
 The hyphae secrete enzymes to aid in the
breakdown of organic materials that are
ultimately absorbed through their cell
walls.
FUNGAL DISEASES
https://www.researchgate.net/publication/325922837_Chitinases-
Potential_Candidates_for_Enhanced_Plant_Resistance_towards_Fungal_Pathogens

5.  Fungi are spread by wind, water, soil, animals, equipment,
and in plant material.
 They enter plants through natural openings such as stomata
and lenticels and through wounds from pruning, hail, and
other mechanical damage.

6. HOST- a living organism from which other organism derives
their food and complete their life cycle.
PATHOGEN- any agent(living organism or virus) that
generate or cause disease in other living organism.
Types of Pathogen: -
 Necrotrophic
 Biotrophic
 Hemibiotrophic
HOST PATHOGEN-INTERACTION
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7. Plant immune system components participate in
 Pathogen Detection.
 Signal Transduction.
 Defense Response.
MECHANISM OF DISEASE RESISTANCE

8. • Pathogen can recognize by is molecules they produce.
• Plant may recognize pathogen directly or indirectly.
• Some pathogen molecules bind directly to plant receptors in
plasma membrane, and some produce enzymes which
breakdown the plant cell wall, and these breakdown
molecules bind to plant receptors.
Molecules involves in pathogen detection
PRR-PATTERN RECOGNITION RECEPTOR
PRR present in plant cell wall.
PAMP/MAMP
PRR
PATHOGEN
PATHOGEN DETECTION

9. • Molecules present inside the cell and helps in cascade
the signals from cell surface to the nucleus of the cell.
• These molecules induce only when pathogen attacks to
the plant.
• They are as:-
MAPK-Mitogen Activated Protein Kinase
NB-LRR- nucleotide binding leucine rich repeat
Effector Molecules
R Protein
SIGNAL TRANSDUCTION

10. • After recognition of pathogen, resistance genes are
activated and in response against pathogen produce
molecules and mechanism which kill the pathogen
aswellas protect the plant form pathogen.
• Molecules and mechanism of defence response :-
 Ion Fluxes
 Oxidative Burst(ROS)
 Phyto-Hormone action
 Phytoalexins
 Systemic Acquired Resistance
 Hypersensitive Response
DEFENSE RESPONSE

11. MECHANISM OF DISEASE RESISTANCE

12.  PAMPs Triggered Immunity (PTI)
 Effector triggered susceptibility (ETS)
 Effector Triggered immunity (ETI)
PHASES OF PLANT IMMUNITY
Friends or foes? Emerging insights from fungal interactions with plants

13.  These molecules referred to as small
molecules conserved within a class of
microbes.
 They are recognized by toll-like receptors
(TLRs) and other pattern recognition
receptors (PRRs) in both plants and
animals.
 different types of molecules can serve as
PAMPs, including glycans and
glycoconjugates.
 PAMPs activate innate immune responses,
protecting the host from infection, by
identifying some conserved nonself
molecules.
PAMP Triggered Immunity (PTI)

14. PAMPs IN PLANTS

15. TRIGGERS PTI SYSTEM
MOLECULAR MECHANISM OF PTI
PATHOGEN PAMP/MAMP
PRR
CELL WALL
PATHOGEN

16. MAPK cascade
EXPRESSION OF DEFENCE GENES
GENE
PRODUCTS
PR -PROTEIN
ION FLUX
PHYTOALEXIN
CHITINASE
SAR
HR

17. EFFECTOR TRIGGERED SUSCEPTIBILITY(ETS)
 Effector are any regulatory
molecules secreted by
pathogens.
 It Modifies host protein to
establish their growth.
 Effector 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.
Host-Microbe Interactions: Shaping the
Evolution of the Plant Immune Response

18.  Effector-triggered immunity (ETI) is
a property of the innate immune
system. ETI was first identified in
plants
 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
• Receptor-like kinases (RLKs)
EFFECTOR TRIGGERED IMMUNITY (ETI)
Host-Microbe Interactions: Shaping the
Evolution of the Plant Immune Response

19. MOLECULAR MECHANISM OF ETI
PATHOGEN EFFECTOR
MOLECULES
NB-LRR
CELL WALL
NUCLEUS
GENE
PRODUCTS
PR -PROTEIN
ION FLUX
PHYTOALEXIN
CHITINASE
SAR
HR

20. ION FLUX
EFFLUX OH
AND K+ IONS
INFLUX Ca+
& H+ IONS
HR
ROS
• Cell death
• Triggered the
deposition of lignin
and callose
SAR
• ADVANCE IMMUNE
SYSTEM IN PLANTS
HORMONAL
SIGNALLING
• JASMONIC ACID
• SALIYCLIC ACID
HYPERSENSITIVE
REAPONSE

21.  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
Hypersensitive response
Ritchie, D.F. 2000. Bacterial spot of pepper and tomato. The Plant Health Instructor.

22. Systemic Acquired Resistance(SAR)
 It is secondary and most advance resistance response.
 A systemic defense response is triggered in distal plant parts
to protect these undamaged tissues against subsequent
invasion by the pathogen.
 Broad-spectrum induced disease resistance
 Act non-specifically through out the plant and reduce
disease severity
 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
plantdefensebio152spring13.wordpress.com

23. PR proteins (PRP)
 Proteins produced in plants when it is attacked by
pathogen, they are antimicrobial/viral/ insecticidal
 it is highly soluble and 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 vice versa.

24. PR Plants in which PRP detected Function Column1
proteins
PR1 Rice, barley, maize, Plant cell wall thickening,
tomato, tobacco resistance to the spread of
the pathogen on the apoplast
PR 2 Rice, barley, maize, tomato, β-1-3-glucanase
tobacco, bean, potato,
PR3 Rice, maize, tomato, pepper, Chitinase
sugar beet, rape seed
PR 4 Tomato, tobacco, rubber tree Chitinase
PR5 Rice, wheat, barley, oats, Alternation of fungal
tomato, tobacco, potato memnrane
PR6 barley, tomato, tobacco Proteinase inhibitor
PR7 Tomato Endoproteinase
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
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25.  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
PHYTOALEXINS

26. CONCLUSION
• Resistance depends on many biochemical components.
• Disease resistance is a response of plant tissues, not
only of single cells, one such function is cell-to-cell
communication.
• Plant resistance potential is depend on its resistance
gene.

27. Thank You