In the following slides, I have discussed the need for developing insect-resistant transgenic plants, the sources of transgenes, and methods for development

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Insect Resistant
Transgenic
Plants
Course Title-PLANT GENETIC TRANSFORMATION
Course Instructor- Ms Sarita Kumari
Dr. V.K. Sharma

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INTRODUCTION
 Insects are the most diverse species of animals that compete for food, fibre and natural
resources.
 One-fifth of the world's total crop production is destroyed by them.
 Indiscriminate use of chemical pesticides results in
 Environmental pollution
 Development of resistance
 Killing of useful insects
 Adverse effect in human health
 Resistant crop varieties are developed using conventional breeding methods, but this
approach is considered inefficient because the methods depend on germplasm and are
time and resource-consuming.

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 TO OVERCOME THESE PROBLEMS
Transgenic crops were generated by introducing the specific gene
of interest into the host with the help of genetic engineering
technology. Expression of these genes coding for insecticidal
activity enables the development of "INSECT RESISTANT
TRANSGENIC PLANTS."
 The first transgenic insect-resistant plant was produces by
introducing cry gene from Bacillus thuringiensis bacterium. Later
the cry gene containing transgenic maize and cotton was
produced commercially.

4. Pests Commonly
Found in Food
Crops
• Moths
• Butterflies
Lepidoptera
• Crickets
• Grasshoppers
Orthoptera
• AphidsHemiptera
• Moths
• Flies
Diptera
• BeetlesColeopterans

5. Sources of Genes for Insect Resistance
From Microbes
• Cry (B.
thuringiensis)
• Vip
(Bacillus
species)
• ChoM
(Streptomyces)
From Insects
• Chitinase
• Avidin (egg
white)
From Plants
• Lectins
• Proteinase
inhibitors
• α-Amylase
inhibitors

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Mechanism Of
Action

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Mechanism Of
Action
cry gene- These toxins will bind to the specific
receptors in the gut of an insect and are solubilized
and activated by specific proteinases, induce the
formation of pores in the insect’s midgut epithelial
membrane, resulting in cell lysis and death.
vip gene- It is responsible for disruption and
swelling of midgut epithelial cells of insects
by osmotic lysis.
choM- Cholesterol oxidase kills the larvae of
boll weevil by disrupting the midgut epithelial
cells at lower doses, and at higher doses cells
are lysed.

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Chitinase- Makes insect pests more
vulnerable to attack by different
pathogens.
Avidin- binds with high affinity to a
ligand biotin that is required by all life
forms as a coenzyme.
Mechanism Of
Action

9. z Lectins- Carbohydrate binding proteins which
disrupt the function by binding to the
midgut epithelial cells of an insect. Thus
inhibitting absorption of nutrients.
Proteinase inhibitors- proteinase inhibitors
which affects the digestion of protein in the gut of
an insect and leads to the deficiency of essential
amino acids.
α-Amylase inhibitors- have a role in the
defense mechanism of plants against insects
by forming a complex with amylases of certain
insect species
Mechanism Of
Action

10. zSteps Involved in Transgenic Development

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Common Methods For
Gene Delivery
Electroporation
Microinjection
Polyethylene Glycol
Biolistics
Agrobacterium

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Tactics For
Deployment
Transgenic plants need to
be integrated with pest
management strategies
as insects have a capacity
to develop resistance to a
wide array of insecticides
• Single Gene
• Multiple gene(Gene Pyramiding)
• Chimeric gene
Gene Strategies
• Constitutive
• Tissue specific
• Inducible(ex. Wounding)
Gene Promoter
• High Dose
• Low dose
• Mixture
Gene Expression
• Uniform single gene
• Mixture of genes
• Gene rotation
• Mosaic Planting
• Refuges(spatial/temporal)
Field Tactics

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Conclusion And Perspective
 The use of transgenic plants provides a way to increase crop production,
benefiting farmers in developed and developing countries by using the resistant
genes either singly or in combination.
 Continuing research on new sources of resistance is essential for the long term
control of insect pests.
 Studies on the expression and potential of the new insecticidal genes can be
performed in model plants such as tobacco and Arabidopsis thaliana. Then, the
selected gene(s) must be introduced into the target crop.
 The introduction of insect-resistant crops must be accompanied by a resistance
management strategy.

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References
1. Insect-Resistant Plants
D. Easwar Rao, K. Divya, I.V.S.N. Prathyusha, Ch. Rama Krishna, K.V. Chaitanya*
GITAM UNIVERSITY, VISAKHAPATNAM, INDIA
2. Biotechnological Prospects for Engineering
Insect-Resistant Plants1[C]
John A. Gatehouse*
School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE,
United Kingdom
3. Insect-Resistant Plants
D. Easwar Rao, K. Divya, I.V.S.N. Prathyusha, Ch. Rama Krishna,
K.V. Chaitanya*
GITAM UNIVERSITY, VISAKHAPATNAM, INDIA

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z Thankyou