engineering plants for nematode resistance
TRANSCRIPT
8/3/2019 Engineering Plants for Nematode Resistance
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ENGINEERING PLANTS
FOR NEMATODE
RESISTANCE
Prepared by
ASWINI RAM
II M.Sc., BIOTECHNOLOGY
SREE NARAYANA GURU COLLEGE- COIMBATORE
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CONTENTS
INTRODUCTION
FEEDING HABITS OF NEMATODES
MORPHOLOGY OF NEMATODES
SYMPTOMS
STRATEGIES FOR ENGINEERING NEMATODE
RESISTANT PLANTS
RESISTANCE MECHANISMS
CONCLUSION
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INTRODUCTION
Nematodes are obligate parasites
Obtain nutrition from plant cytoplasm
Species includes ectoparasites and endoparasites
Sedentary endoparasites of the family Heteroderidae
cause most economic damage
Heteroderidae divided into 2 groups
1) Cyst nematodes 2) Root knot nematodes
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FEEDING HABITS OF NEMATODES
Ectoparasitic nematodes
Live completely outside the plant
Migratory endoparasitic nematodes
Live completely inside the plant but move freelybetween the roots and soil
Sedentary endoparasitic nematodes
Live inside the plant but adult female becomes
sedentarySemi- endoparasitic nematodes
Part of body inside root. By movement when feeding
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NNMMCMKMCDSKMOMMMORPHOLOGY
DIGESTIVE
ORGANS
REPRODUCTIV
E ORGANS
EXCREATORY
STRUCTURES
MUSCLES
NERVES
TOUGH SKIN
OR CUTICLE
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PLANT PARASITIC NEMATODES ALL HAVE
STYLETS (SPEARS) THAT PENETRATE
CELLS AND WITHDRAW THE CONTENTS
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SYMPTOMS
Yield loss
Stunting
Yellowing
Water deficiency and wilting
Nutrient deficiency
Direct damage
( knots on roots in potatoes , peanuts.,etc)
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CYST NEMATODES ON ROOTES
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POTATO ROT NEMATODE
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PEANUT POD GALLING
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MOLECULAR STRATEGIES FOR
ENGINEERING NEMATODE RESISTANCE
IN PLANTS
1. Strategies targeting directly the nematode
2. Strategies aimed at using or reinforcing existing plant
defense mechanisms
3. Strategies aimed at interfering in the nematode- plant
interaction
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1.STRATEGIES TARGETING DIRECTLY
THE NEMATODE
Exploit the structural difference between nematodes and
plants
Eg:- chitin and collagen, both are important components
of the nematode and absent in plants
Transgenic plants expressing chitinase and collagenasewere constructed
Nematode resistant plants have not been reported so far
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Cowpea Trypsin inhibitor [CpTI] isolated from Cowpea
(Vigna unguiculata) and the insecticidal crystal proteins
produced by B.thuringiensis isolates.
CpTI affected the sexual development of sedentary
endoparasitic cyst nematode Globodera palleda
Strategies aimed at targeting internal
nematode structures
Cont..
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2. STRATEGIES AIMED AT USING OR
REINFORCING EXISTING PLANT
DEFENSE MECHANISMS
Isolating resistant genes and expressed in higher plants
Nematode resistant genes are present in several cropspecies
Important component of many breeding programsincluding those for tomato, soyabeans and cereals are
1. HsIPro-I
Against Heterodera schachtii.
2. Mi-I
Against Macrosiphum euphorbiae.
3. Gpa2
Against Globodera pallida.
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LR TM
HsIPro-I
LZ NBS LRRMi-I
LZ NBS LRR Gpa2
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3.STRATEGIES AIMED AT INTERFERING IN
THE NEMATODE- PLANT INTERACTION
Strategies aimed at blocking the nematode- plant
recognition- transgenic plant produce lectins
Strategies aimed at the inhibition or destruction of
specialised feeding structures
1. Destroy plant cells present in syncytium
2. Proteins synthesized by nematodes for the
maintenance of syncytium destroyed by plantibodies
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RESISTANCE MECHANISMS
1. In resistant tomatoes a localized necrosis, suggesting a HR is
visible near the anterior end of the nematode within a few
days of infection.
2. HI (Gpa2) mediated resistance of potato, the feeding site
becomes surrounded by necrotic tissues and collapses.
3. HsIPro-I
Not involved in hypersensitive response. Nematode die in the
last J2 stage. Because of degradation of the feeding
structure(syncytium) in the host.
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RESISTANT / NOT RESISTANT
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CONCLUSION
Incorporation of natural resistance is a major strategy in
nematode management.
Not certain that genes function effectively in heterologous
hosts.
Investigation of cloned R genes allowed development of
designer R genes with faster response, broader target
recognition or increased durability.
Understanding the interactions between host and pathogen
increase options for control strategies.
Use of chemical nematicides decreases.
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