Applications of transgenic plants_II.pptx

1. Applications of Transgenic
Plants:

2. Two popular strategies to make Insect
Resistant Transgenic Plants
• Utilizing insecticidal property of biological insecticides i.e. Bacillus thuringiensis
• Use natural insecticidal/defence property of some plants or other source.

3. Quick Revision
• Biological Insecticides.
• In 1950s, it was found that during sporulation, several Bt strains
produce crystals proteins (proteinaceous inclusions), called delta-endotoxins
that are insecticidal in nature. The toxin does not persist in the environment.

4. Toxic Potential of Bacillus thuringiensis: An Overview |
IntechOpen

5. • To raise the level of the expressed protein, scientists truncated the gene so that
only the N-terminal portion of the insecticidal protoxin—the part of the
protoxin that contains the toxin was produced and inserted a strong plant
promoter to direct gene expression.
• Further it was partially modified followed by fully modified version that led to
higher expression of the gene in plants.
Quick Revision

6. Bt cotton in India - Google Search

7. Two popular strategies to make Insect
Resistant Transgenic Plants
• Utilizing insecticidal property of biological insecticides i.e. Bacillus thuringiensis
• Use natural insecticidal/defence property of some plants.

8. Protease Inhibitors
• Plants defence proteins against insects/pests.
• For example, some plants produce protease inhibitors that, when ingested,
prevent the feeding insect from hydrolysing plant proteins, thereby effectively
starving the predator insect.
• Consequently, it seemed reasonable to isolate a plant gene for a protease
inhibitor, add a strong promoter, and create transgenic crop plants that produce
sufficiently high levels of the protease inhibitor to reduce damage from insect
predation.
Glick and Pasternak

9. Cowpea trypsin Inhibitors
• The cowpea plants were shown to have natural resistance against wide range of insects.
• Insecticidal protein – trypsin inhibitors.
• The full-length cDNA or Gene encoding for cowpea trypsin inhibitor is isolated and put in the
binary vector. Following A. tumefaciens infection of tobacco leaf disks with this vector, cells that
incorporated the cloned DNA were selected for growth on kanamycin, and transgenic plants
were regenerated.
• The damage caused by Heliothis virescens (tobacco budworm) larvae to transgenic plants that
expressed more than 2 mg of cowpea trypsin inhibitor per mg of protein was significantly less
than the damage inflicted on nontransformed plants.
• Cowpea seeds that contain approximately 2 mg of inhibitor per mg of plant protein are not
toxic to either animals or humans.

11. • Proteinase inhibitor II : Introduction of the potato proteinase inhibitor II gene
provides rice plants with protection against the pink stem borer (Sesamia
inferens), a major insect pest of rice.
• An α-amylase inhibitor from common bean in transgenic pea - specially works
against the cowpea weevil (Callosobruchus maculatus) and the azuki bean
weevil (Callosobruchus chinensis) (seed-feeding beetles that cause considerable
economic loss of these legume crops, especially in developing countries).

12. Fusion of Two strategies to make Insect
Resistant Transgenic Plants
• Utilizing insecticidal property of biological insecticides i.e. Bacillus thuringiensis
• Use natural insecticidal/defence property of some plants.
Effect of Bacillus thuringiensis (Bt) Cry1Ac toxin and protease inhibitor on growth and
development of Helicoverpa armigera (Hübner) - ScienceDirect

13. Genes from Other bacteria with insecticidal
properties
• Cholesterol oxidase of Strepotmyces culture – toxic against boll weevil larvae.
• Isopentenyl transferase gene from Agrobacterium tumefaciens has been
introduced into tobacco and tomato. This gene codes for an important enzyme
in the synthesis of cytokinin. The transgenic plants with this transgene were
found to show less leaf consumption by tobacco hornworm and death of peach
potato aphid.

14. Application of Transgenic plants:
Herbicide Resistant Plants

15. Herbicide
• Weeds are unwanted plants that tends to grow along with main crops.
• To control weeds, the chemical used is known as Herbicides.

16. Herbicides - Limitations
• Generalized effects (kill main crops as well)
Broad-spectrum herbicides
• Specific one - Harmful for nature
(as recalcitrant, contributes to
soil and water pollution.) Health
hazards to human beings/
animals (mild to severe effects)
High cost
chemical Insecticides - Google Search

17. Herbicide Resistant Transgenic Plants
• Confer resistance to herbicides.
• With the advent of genetic engineering approach, it is possible to generate
plants which demonstrate resistance to broad-spectrum herbicide so that only
weeds are killed on exposure to herbicides without any deleterious effects on
the main plants.
• For example : Round Up (Herbicides – Glyphosate) is a common weed killer and
broad spectrum properties. Round-up ready crops can be made using genetic
engineering technology.

18. Why Roundup Ready Crops Have Lost their Allure - Science in the News
(harvard.edu)

19. Approach to make Herbicide Resistant
Transgenic Plants
Genetic manipulation cab be done:
1. Inhibit uptake of herbicide
2. Over-produce herbicide-sensitive target protein so that enough of it remains
available for cellular functions.
3. Introduce a foreign gene that codes for protein that performs the similar
function as herbicide-sensitive target protein but resistant to herbicide.
4. Reduce ability of herbicide-sensitive target protein to bind to herbicide.
5. Endow plants with the capability to metabolically inactivate the herbicide.

20. Glyphosate
• Environment-friendly weed killer “Round-Up” as it rapidly degraded to non-
toxic compound in the soil.
• Effective, safe and cheap
• Generalized.
• It generally acts/inhibits 5 enolpyruvylshikimate-3-phosphate synthetase
(EPSPS) enzyme in shikimate pathways (the pathways – synthesis of aromatic
amino acids in both bacteria and plants).

22. Glyphosate-resistant plants
• One approach is to isolate glyphosate-resistant EPSPS gene from
E.coli/Agrobacterium and used as transgene to develop transgenic plants.
• Crops that have been engineered to be resistant to glyphosate by this approach
are said to be “Roundup ready.”
• For example : soyabean, tomato, corn, potato etc.
• Another approach is to inactivate glycophosate
(a) By its acetylation via gene product/enzyme isolated from Bacillus sp.
(a) By its oxidation by the enzyme glyphosate oxidase from the soil microorganisms Ochrobactrum
anthropi

24. • Widely used, safe and non-toxic to control broadleaf weeds
• When it is applied to dicotyledonous plants, dicamba acts by mimicking the
effects of high levels of the plant hormone indole-3-acetic acid and binding to
indole-3-acetic acid receptors, which are essential for normal growth and
development of the plant.
• The dicamba monooxygenase (enzyme - part of the three-component enzyme
dicamba O-demethylase, from the bacterium Pseudomonas maltophilia) that
converts dicamba to 3,6-dichlorosalicylic acid, a compound without any
appreciable herbicidal activity. A dicamba monooxygenase gene was expressed
in Arabidopsis, tomato, and tobacco.
Dicamba

26. Bromoxynil
• Herbicide that inhibits photosynthesis.
• A bacterial gene (from Klebsiella Ozaenae) encoding nitrilase can inactivate
bromoxynil.

27. Glyfosinate/Phosphinothricin
• Basta Aventis/Buster/Liberty
• Phosphinothricin is an unusual herbicide, being a derivative of a natural
product namely bialaphos. Certain species of Streptomyces produce bialaphos
which is a combination of phosphinothricin bound to two alanine residues,
forming a tripeptide. By the action of a peptidase, bialaphos is converted to
active phosphinothricin
• Herbicide that inhibits key enzyme in nitrogen assimilation pathways. It leads to
ammonia toxicity and loss of photosynthesis.
• A bacterial bar gene (from streptomyces Hygroscopicus) can inactivate
glyfosinate.

31. Dhara Mustard Hybrid 11 (DMH 11)
(Glyfosinate/Phosphinothricin resistant)
Developed by renowned geneticist Deepak Pental (former vice-chancellor of Delhi University) and his team, with
support from the National Dairy Development Board and the department of biotechnology, Dhara Mustard Hybrid will
help our farmers increase mustard productivity.
(30) All About Mustard DMH-11 (Dhara Mustard Hybrid) GM crop. - YouTube

32. Applications of Transgenic Plants
• Resistance to biotic stress
• Resistance to abiotic stress
• Improvement of crop yield and quality
• Improved/enhanced nutritional value
• Bioreactors
• phytoremediation
Applications of Transgenic Plants: 6 Applications (biologydiscussion.com)
Transgenic plants with beneficial traits (brainkart.com)

33. Resistance to Biotic Stress
• Insects
• Fungus (Bengal feminie)
• Viruses (papaya ringspot virus)
• Bacteria

34. Resistance to Abiotic Stress
• Herbicides
• Temperature
• Salinity
• Drought
• Extreme environment

35. Improvement of crop yield and quality
• Longer shelf life
• Good quality
(by modifying polygalactouronase/cellulase/ethylene signalling)

37. Modification of plant products
• Modify protein/oil content of different plants.
• Taste of fruits, vegetables by introduction of Monellin (sweet tasting protein)
• For example : Introduction of Vitamin A in rice (golden rice)

38. • Prof. Ingo Potrykus and Dr. Peter Beyer developed genetically engineered rice (popularly known
as 'Golden Rice’)
• Rich in pro-vitamin A (beta-carotenoids) by introducing three genes involved in the biosynthetic
pathway for carotenoid under the control of endosperm-specific promoter, so that gene
products (enzymes) are synthesized in the rice endosperm.
Modification of plant products

39. Bioreactors
• Proteins
• Monoclonal antibodies
• Growth hormones
• Cytokinins
• Edible vaccines

40. • Transgenic plants can be used as factories to produce biodegradable plastics
PHB polyhydroxybutyrate.
• The genetically engineered Arabidopisis plants with the three genes involved in
PHB synthesis from A. eutrophus produced PHB globules exclusively in their
chloroplasts without effecting plant growth and development.
Phytoremediation

41. • Manipulation of flavonoid biosynthesis pathway.
Generation of unique-coloured flowers
Flower phenotypes in transgenic tobacco plants. Untransformed tobacco was indicated as " wild-type (W38) " , which had pink color in flowers. Fainter color was observed
in a transgenic line CHS11. Deeper colors with different patterns were observed in a transgenic line CHI4, and a line from the cross of CHS11 and CHI4 (indicated as
CHS11xCHI4). Faint red in rim of flower petal was observed in a line from the cross of CHI4 and CHS7 (indicated as CHI4xCHS7). Flowers with complete white color were
observed in a transgenic line CHS10
Flower-phenotypes-in-transgenic-tobacco-plants-Untransformed-tobacco-was-indicated-as.png (850×586) (researchgate.net)

42. Transgenic plants with beneficial traits (brainkart.com)

43. Transgenic plants with beneficial traits (brainkart.com)

44. • Biodiversity
• Effects of insects, spiders
• Out-crossing and Gene flow
• Damage to human health
• Horizontal transfer and antibiotics resistance
Risks and Concerns……