This document discusses the role of biotechnology in developing biotic stress tolerance in crops. It focuses on using genetic engineering to develop herbicide and insect resistance. For herbicide resistance, it describes how glyphosate resistance was developed by introducing genes for the CP4 EPSPS enzyme. For insect resistance, it details how the Bt gene from Bacillus thuringiensis was introduced to produce Bt toxins that target specific insect pests like the bollworm when ingested. The mode of action of Bt toxins in disrupting the insect gut is also summarized.
For centuries, humans have searched for crop plants that can survive and produce in spite of insect pests.
Knowingly or unknowingly, ancient farmers selected for pest resistance genes in their crops, sometimes by actions as simple as collecting seed from only the highest-yielding plants in their fields.
With the advent of genetic engineering, genes for insect resistance now can be moved into plants more quickly and deliberately.
Bt technology is only one example of ways genetic engineering may be used to develop insect-resistant crops now and in the future.
Highly descriptive and illustrative presentation based on Biotechnology chapter 12 of NCERT class XII.
This is an important topic especially from biological research point of view.
This is to help students thoroughly understand the topic for exams as well as for future practical applications.
Introduction
Definition of an Insect Resistant Plant
What is the Bt gene?
History
The crystal ( cry)Proteins
Definition of cry protein
How does Bt work?
Mechanism of Bt toxicity
Mode of Action of Insecticidal Crystal Protein
Bt Technology
The Insect Resistance Problem
Advantages
Limitations
Conclusion
References
For centuries, humans have searched for crop plants that can survive and produce in spite of insect pests.
Knowingly or unknowingly, ancient farmers selected for pest resistance genes in their crops, sometimes by actions as simple as collecting seed from only the highest-yielding plants in their fields.
With the advent of genetic engineering, genes for insect resistance now can be moved into plants more quickly and deliberately.
Bt technology is only one example of ways genetic engineering may be used to develop insect-resistant crops now and in the future.
Highly descriptive and illustrative presentation based on Biotechnology chapter 12 of NCERT class XII.
This is an important topic especially from biological research point of view.
This is to help students thoroughly understand the topic for exams as well as for future practical applications.
Introduction
Definition of an Insect Resistant Plant
What is the Bt gene?
History
The crystal ( cry)Proteins
Definition of cry protein
How does Bt work?
Mechanism of Bt toxicity
Mode of Action of Insecticidal Crystal Protein
Bt Technology
The Insect Resistance Problem
Advantages
Limitations
Conclusion
References
Introduction: Biotechnology is an emerging field of research as it has the potential to solve many biological problems which could not be solved till now with conventional techniques.
The use of biology to develop technologies and products for the welfare of human beings is known as Biotechnology. It has various applications in different fields such as Therapeutics, Diagnostics, Processed Food, Waste Management, Energy Production, Genetically Modified Crops etc.
Biotechnology means 'applications of scientific and engineering principles to biological processes to provide goods and services'. Full understanding of biological processes is possible with detailed analysis of gene structure and function i.e. the Genetic Engineering means the introduction of manipulated genetic material (DNA) into a cell in such a way as to replicate and be passed on to progeny cells'. The outcome is attractive and promising.
The biotic stresses are caused by insects, pathogens (viruses, fungi, bacteria), and wounds. The abiotic stresses are due to herbicides, water deficiency (caused by drought, temperature, and salinity), ozone and intense light.
Insect-resistant transgenic crops were first commercialized in the mid-1990s with the introduction of GM corn (maize), potato and cotton plants expressing genes encoding the entomocidal δ-endotoxin from Bacillus thuringiensis (Bt; also known as Cry proteins). In 2010, 148 million ha of biotech crops were grown in 29 countries, representing 10% of all 1.5 billion hectares of cropland in the world. The global value of this seed alone was valued at US $11.2 billion in 2010, with commercial biotech maize, soybean grain and cotton valued at approximately US $150 billion per year. In recent years, it has become evident that Bt-expressing crops have made a significant beneficial impact on global agriculture, not least in terms of pest reduction and improved quality. However, because of the potential for pest populations to evolve resistance, and owing to lack of effective control of homopteran pests, alternative strategies are being developed. Some of these are based on Bacillus spp., e.g. vegetative insecticidal proteins (VIPs) or other insect pathogens.
Bt-corn is a type of genetically modified organism, termed GMO. A GM.pdfanurag1231
Bt-corn is a type of genetically modified organism, termed GMO. A GMO is a plant or animal
that has been genetically modified through the addition of a small amount of genetic material
from other organisms through molecular techniques. Currently, the GMOs on the market today
have been given genetic traits to provide protection from pests, tolerance to pesticides, or
improve its quality. Examples of GMO field crops include Bt-potatoes, Bt-corn, Bt-sweet corn,
Roundup Ready soybeans, Roundup Ready Corn, and Liberty Link corn.
Genetically modified foods are foods derived from GMO crops. For example, corn produced
through biotechnology is being used in many familiar foods, including corn meal and tortilla
chips. In addition, corn is used to make high fructose corn syrup, which is used as a sweetener in
many foods such as soft drinks and baked goods. While the FDA (U.S. Food and Drug
Administration) regulates genetically modified foods, it considers Bt-corn to be nutritionally
equivalent to traditional corn.
To transform a plant into a GMO plant, the gene that produces a genetic trait of interest is
identified and separated from the rest of the genetic material from a donor organism. Most
organisms have thousands of genes, a single gene represents only a tiny fraction of the total
genetic makeup of an organism.
A donor organism may be a bacterium, fungus or even another plant. In the case of Bt corn, the
donor organism is a naturally occurring soil bacterium, Bacillus thuringiensis, and the gene of
interest produces a protein that kills Lepidoptera larvae, in particular, European corn borer. This
protein is called the Bt delta endotoxin. Growers use Bt corn as an alternative to spraying
insecticides for control of European and southwestern corn borer.
Bt Delta Endotoxin
The Bt delta endotoxin was selected because it is highly effective at controlling Lepidoptera
larvae, caterpillars. It is during the larval stage when most of the damage by European corn borer
occurs. The protein is very selective, generally not harming insects in other orders (such as
beetles, flies, bees and wasps). For this reason, GMOs that have the Bt gene are compatible with
biological control programs because they harm insect predators and parasitoids much less than
broad-spectrum insecticides. The Bt endotoxin is considered safe for humans, other mammals,
fish, birds, and the environment because of its selectivity. Bt has been available as a commercial
microbial insecticide since the 1960s and is sold under many trade names. These products have
an excellent safety record and can be used on many crops until the day of harvest.
To kill a susceptible insect, a part of the plant that contains the Bt protein (not all parts of the
plant necessarily contain the protein in equal concentrations) must be ingested. Within minutes,
the protein binds to the gut wall and the insect stops feeding. Within hours, the gut wall breaks
down and normal gut bacteria invade the body cavity. The i.
To decrease our world hunger and to make the plant more nutritious the transgenic technique was developed. This the basis of the transgenic plant and its technique
Application Of Genetic Engineering In Industrial Microbiology And BiotechnologyZohaib HUSSAIN
The property of DNA to replicate and reproduce and to have a sequence also called as coding sequence for mRNA and ultimately for protein. The most important feature of DNA is if DNA coding for protein is from one organism is copy and paste in another it will express there to. This feature is manipulated for benefit of humans using technique called recombinant DNA Technology using which lots of improvements are done in agriculture, health care sector and industrial sector.
Introduction: Biotechnology is an emerging field of research as it has the potential to solve many biological problems which could not be solved till now with conventional techniques.
The use of biology to develop technologies and products for the welfare of human beings is known as Biotechnology. It has various applications in different fields such as Therapeutics, Diagnostics, Processed Food, Waste Management, Energy Production, Genetically Modified Crops etc.
Biotechnology means 'applications of scientific and engineering principles to biological processes to provide goods and services'. Full understanding of biological processes is possible with detailed analysis of gene structure and function i.e. the Genetic Engineering means the introduction of manipulated genetic material (DNA) into a cell in such a way as to replicate and be passed on to progeny cells'. The outcome is attractive and promising.
The biotic stresses are caused by insects, pathogens (viruses, fungi, bacteria), and wounds. The abiotic stresses are due to herbicides, water deficiency (caused by drought, temperature, and salinity), ozone and intense light.
Insect-resistant transgenic crops were first commercialized in the mid-1990s with the introduction of GM corn (maize), potato and cotton plants expressing genes encoding the entomocidal δ-endotoxin from Bacillus thuringiensis (Bt; also known as Cry proteins). In 2010, 148 million ha of biotech crops were grown in 29 countries, representing 10% of all 1.5 billion hectares of cropland in the world. The global value of this seed alone was valued at US $11.2 billion in 2010, with commercial biotech maize, soybean grain and cotton valued at approximately US $150 billion per year. In recent years, it has become evident that Bt-expressing crops have made a significant beneficial impact on global agriculture, not least in terms of pest reduction and improved quality. However, because of the potential for pest populations to evolve resistance, and owing to lack of effective control of homopteran pests, alternative strategies are being developed. Some of these are based on Bacillus spp., e.g. vegetative insecticidal proteins (VIPs) or other insect pathogens.
Bt-corn is a type of genetically modified organism, termed GMO. A GM.pdfanurag1231
Bt-corn is a type of genetically modified organism, termed GMO. A GMO is a plant or animal
that has been genetically modified through the addition of a small amount of genetic material
from other organisms through molecular techniques. Currently, the GMOs on the market today
have been given genetic traits to provide protection from pests, tolerance to pesticides, or
improve its quality. Examples of GMO field crops include Bt-potatoes, Bt-corn, Bt-sweet corn,
Roundup Ready soybeans, Roundup Ready Corn, and Liberty Link corn.
Genetically modified foods are foods derived from GMO crops. For example, corn produced
through biotechnology is being used in many familiar foods, including corn meal and tortilla
chips. In addition, corn is used to make high fructose corn syrup, which is used as a sweetener in
many foods such as soft drinks and baked goods. While the FDA (U.S. Food and Drug
Administration) regulates genetically modified foods, it considers Bt-corn to be nutritionally
equivalent to traditional corn.
To transform a plant into a GMO plant, the gene that produces a genetic trait of interest is
identified and separated from the rest of the genetic material from a donor organism. Most
organisms have thousands of genes, a single gene represents only a tiny fraction of the total
genetic makeup of an organism.
A donor organism may be a bacterium, fungus or even another plant. In the case of Bt corn, the
donor organism is a naturally occurring soil bacterium, Bacillus thuringiensis, and the gene of
interest produces a protein that kills Lepidoptera larvae, in particular, European corn borer. This
protein is called the Bt delta endotoxin. Growers use Bt corn as an alternative to spraying
insecticides for control of European and southwestern corn borer.
Bt Delta Endotoxin
The Bt delta endotoxin was selected because it is highly effective at controlling Lepidoptera
larvae, caterpillars. It is during the larval stage when most of the damage by European corn borer
occurs. The protein is very selective, generally not harming insects in other orders (such as
beetles, flies, bees and wasps). For this reason, GMOs that have the Bt gene are compatible with
biological control programs because they harm insect predators and parasitoids much less than
broad-spectrum insecticides. The Bt endotoxin is considered safe for humans, other mammals,
fish, birds, and the environment because of its selectivity. Bt has been available as a commercial
microbial insecticide since the 1960s and is sold under many trade names. These products have
an excellent safety record and can be used on many crops until the day of harvest.
To kill a susceptible insect, a part of the plant that contains the Bt protein (not all parts of the
plant necessarily contain the protein in equal concentrations) must be ingested. Within minutes,
the protein binds to the gut wall and the insect stops feeding. Within hours, the gut wall breaks
down and normal gut bacteria invade the body cavity. The i.
To decrease our world hunger and to make the plant more nutritious the transgenic technique was developed. This the basis of the transgenic plant and its technique
Application Of Genetic Engineering In Industrial Microbiology And BiotechnologyZohaib HUSSAIN
The property of DNA to replicate and reproduce and to have a sequence also called as coding sequence for mRNA and ultimately for protein. The most important feature of DNA is if DNA coding for protein is from one organism is copy and paste in another it will express there to. This feature is manipulated for benefit of humans using technique called recombinant DNA Technology using which lots of improvements are done in agriculture, health care sector and industrial sector.
Various virus vector related to Plant and Animal for gene cloning and transfo...PrabhatSingh628463
Various virus vector related to Plant and Animal for gene cloning and transformation and Expression vector and it’s mode of expression in plant and animal cells
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
Andreas Schleicher presents at the OECD webinar ‘Digital devices in schools: detrimental distraction or secret to success?’ on 27 May 2024. The presentation was based on findings from PISA 2022 results and the webinar helped launch the PISA in Focus ‘Managing screen time: How to protect and equip students against distraction’ https://www.oecd-ilibrary.org/education/managing-screen-time_7c225af4-en and the OECD Education Policy Perspective ‘Students, digital devices and success’ can be found here - https://oe.cd/il/5yV
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.
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.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Cambridge International AS A Level Biology Coursebook - EBook (MaryFosbery J...
Role of biotechnology in development biotic stress tolerance in crops.pptx
1. ASSIGNMENT on BT622
Topic – Role of Biotechnology in development
of biotic stress tolerance in crops
Presented by
Prabhat Kumar Singh
Ph.D. I year
Ag-Biotechnology
ACHARYA NARENDRA DEVA UNIVERSITY OF
AGRICULTURE AND TECHNOLOGY AYODHYA
Presented to –Dr. Shambhoo Prasad
Designation -Associate prof.
(Dept of PMB and GE)
3. Genetic engineering for Herbicide resistance
First Major achievement from genetic
engineering in plants.
Glyphosate ,Glufosinate, Sulfonylureas etc.
have been successfully ,Commercially
cultivated in USA and other countries.
Glyphosate
4.
5. Details
Glyphosate, a weed killer, was introduced in the market by Monsanto Company
during 1970s.
It is a leading broad spectrum, non-selective, systemic herbicide for the control of
annual and perennial weeds before the emergence of any agronomic crops.
It is also used in non-crop and plantation crops. It is marketed under the trade
name Roundup.
Glyphosate is used against the annual broadleaf weeds and grasses that compete
with the crops.
When applied, it is absorbed through foliage and minimally through roots which
means it is only effective on active growing plants and cannot prevent seeds from
germinating. Recommended dose of application rates of glyphosate do not exceed
5.8 kg a.i. ha-1.(Active ingredients).
6. Mode of Action.
Glyphosate has often been termed as a “once-in-a-century herbicide”
because of its tremendous impact on weed management and the crop
production industry.
Glyphosate blocks the synthesis of essential amino acids through binding
and subsequent inactivation of an enzyme (EPSPS) that is critical in the
shikimate pathway .
By disrupting the synthesis of such defense compounds in plants, glyphosate
predisposes the crops to attack by soil-borne pathogens. Hence, it could be
argued that continuous crop exposure to glyphosate may increase plant
susceptibility to diseases .
7. CP4 EPSPS: The gene conferring resistance to the herbicide
Roundup
The gene was found in Agrobacterium tumefaciens and
transferred to various plants
Coincidentally, this organism is also used for creating
transgenic plants
TGGAAAAGGAAGGTGGCTCCTACAAATGCCATCATTGCGATAAAGGAAAGGCCATCGTTGAAGATGCCTCTGCCGACAGTGGTCCCAAAG
ATGGACCCCCACCCACGAGGAGCATCGTGGAAAAAGAAGACGTTCCAACCACGTCTTCAAAGCAAGTGGATTGATGTGATATCTCCACTGA
CGTAAGGGATGACGCACAATCCCACTATCCTTCGCAAGACCCTTCCTCTATATAAGGAAGTTCATTTCATTTGGAGAGGACACGCTGACAAG
CTGACTCTAGCAGATCTTTCAAGAATGGCACAAATTAACAACATGGCACAAGGGATACAAACCCTTAATCCCAATTCCAATTTCCATAAACC
CCAAGTTCCTAAATCTTCAAGTTTTCTTGTTTTTGGATCTAAAAAACTGAAAAATTCAGCAAATTCTATGTTGGTTTTGAAAAAAGATTCAATT
TTTATGCAAAAGTTTTGTTCCTTTAGGATTTCAGCATCAGTGGCTACAGCCTGCATGCTTCACGGTGCAAGCAGCCGGCCCGCAACCGCCCG
CAAATCCTCTGGCCTTTCCGGAACCGTCCGCATTCCCGGCGACAAGTCGATCTCCCACCGGTCCTTCATGTTCGGCGGTCTCGCGAGCGGTG
AAACGCGCATCACCGGCCTTCTGGAAGGCGAGGACGTCATCAATACGGGCAAGGCCATGCAGGCCATGGGCGCCAGGATCCGTAAGGAA
GGCGACACCTGGATCATCGATGGCGTCGGCAATGGCGGCCTCCTGGCGCCTGAGGCGCCGCTCGATTTCGGCAATGCCGCCACGGGCTGC
CGCCTGACCATGGGCCTCGTCGGGGTCTACGATTTCGACAGCACCTTCATCGGCGACGCCTCGCTCACAAAGCGCCCGATGGGCCGCGTGT
TGAACCCGCTGCGCGAAATGGGCGTGCAGGTGAAATCGGAAGACGGTGACCGTCTTCCCGTTACCTTGCGCGGGCCGAAGACGCCGACGC
CGATCACCTACCGCGTGCCGATGGCCTCCGCACAGGTGAAGTCCGCCGTGCTGCTCGCCGGCCTCAACACGCCCGGCATCACGACGGTCAT
CGAGCCGATCATGACGTGCGATCATACGGAAAAGATGCTGCAGGGCTTTGGCGCCAACCTTACCGTCGAGACGGATGCGGACGGCGTGC
GCACCATCCGCCTGGAAGGCCGCGGCAAGCTCACCGGCCAAGTCATCGACGTGCCGGGCGACCCGTCCTCGACGGCCTTCCCGCTGGTTG
CGGCCCTGCTTGTTCCGGGCTCCGACGTCACCATCCTCAACGTGCTGATGAACCCCACCCGCACCGGCCTCATCCTGACGCTGCAGGAAATG
GGCGCCGACATCGAAGTCATCAACCTGCGCCTTGCCGGCGGCGAAGACGTGGCGGACCTGCGCGTTCGCTCCTCCACGCTGAAGGGCGTC
ACGGTGCCGGAAGACCGCGCGCCTCCGATGATCGACGAATATCCGATTCTCGCTGTCGCCGCCGCCTTCGCGGAAGGGGCGACCGTGATG
AACGGTCTGGAAGAACTCCGCGTCAAGGAAAGCGACCGCCTCTCGGCCGTCGCCAATGGCCTCAAGCTCAATGGCGTGGATTGCGATGAG
GGCGAGACGTCGCTCGTCGTGCGTGGCCGCCCTGACGGCAAGGGGCTCGGCAACGCCTCGGGCGCCGCCGTCGCCACCCATCTCGATCAC
CGCATCGCCATGAGCTTCCTCGTCATGGGCCTCGTGTCGGAAAACCCTGTCACGGTGGACGATGCCACGATGATCGCCACGAGCTTCCCGG
AGTTCATGGACCTGATGGCCGGGCTGGGCGCGAAGATCGAACTCTCCGATACGAAGGCTGCCTGATGAGCTCGAATTCGAGCTCGGTACC
GGATCCAATTCCCGATCGTTCAAACATTTGGCAATAAAGTTTCTTAAGATTGAATCCTGTTGCCGGTCTTGCGATGATTATCATATAATTTCT
GTTGAATTACGTTAAGCATGTAATAATTAACATGTAATGCATGACGTTATTTATGAGATGGGTTTTTATGATTAGAGTCCCGCAATTATACAT
TTAATACGCGATAGAAAACAAAATATAGCGCGCAAACTAGGATAAATTATCGCGCGCGGTGTCATCTATGTTACTAGATCGGGGATCGATC
CCCCACCGGTCCTTCATGTTCGGCGGTCTCGCGAGCGGTGAAACGCGCATCACCGGCCTTCTGGAAGGCGAGGACGTCATCAATACGGGC
AAGGCCATGCAGGCCATGGGCGCCAGGATCCGTAAGGAAGGCGACACCTGGATCATCGATGGCGTCGGCAATGGCGGCCTCCTGGCGCC
TGAGGCGCCGCTCGATTTCGGCAATGCCGCCACGGGCTGCCGCCTGACCATGGGCCTCGTCGGGGTCTACGATTTCAAGCGCATCATGCTG
GGAA
10. Strategies for Glyphosate resistance crops
Overproduction of EPSPS enzyme
Encode an EPSPS enzyme that is tolerant to glyphosate
Produce an enzyme that inactivates glyphosate
Use a combination of 2 and 3
11. Advantages
When applied appropriately, it can promote useful effects. In sugarcane,
for example, glyphosate application increases sucrose concentration
before harvest.
Use of glyphosate based herbicides reduces the need for conventional
tilling thereby reducing carbon dioxide emissions.
Pure glyphosate is low in toxicity to fish and other wildlife, and it binds
tightly to soil so is unlikely to contaminate groundwater.
Use of glyphosate based herbicides reduces the need for labor-intensive
weed control, reduce pest pressure and improve crop quality and yield.
12. Glyphosate based herbicides have a shorter active life span and safer chemistry
than many other herbicides, when used as per product label.
Disadvantages
Transgenic food product may allergy to human
Affect the soil flora
Developing super weeds
Affect natural Germplasm
15. Bacillus thuringinesis
Bacillus thuringiensis (or Bt) is a gram-positive, soil-dwelling bacterium, the
most commonly used biological pesticide worldwide.
B. thuringiensis also occurs naturally in the gut of caterpillars of various types
of moths and butterflies, as well on leaf surfaces, aquatic environments, animal
feces, insect-rich environments, and flour mills and grain-storage facilities.
During sporulation many Bt strains produce crystal proteins
(proteinaceous inclusions), called delta endotoxins that
have insecticidal action.
This has led to their use as insecticides, and more recently
to genetically modified crops using Bt genes, such as Bt corn. Many
crystal-producing Bt strains though, do not have insecticidal properties.
16. The crystal
The crystal, referred to as Cry toxin (cry from crystal), insecticidal crystal protein,
parasporal body, crystalline inclusion, or delta endotoxin, is a protein formed
during sporulation in Bt strains and aggregate to form crystals.
Such Cry toxins are toxic to specific species of insects belonging to
Lepidoptera, Coleoptera, Hymenoptera, Diptera, and Nematoda.
They are harmless to human, vertebrates, and natural enemies of insects
In addition to the Cry toxins, some strains of Bt, like Bt israelensis, produce
another toxic crystal, named cytolytic protein or Cyt toxin.
17. The cry protein has three
domains: an alpha helical N
terminal domain, domain I;
a Greek key beta sheet
domain II;
and a "jelly roll" antiparallel
b-sandwich domain III.
The core of the protein is
the most highly conserved,
with Helix 5 of Domain I and
the areas of contact between
the domains being the most
highly conserved.
Structure of Cry Protein
18. Bt cotton is one of the first crop
protection products from
biotechnology.
Bt cotton is a genetically
modified organism (GMO) or
genetically modified pest resistant
plant, which produces an
insecticide to combat bollworm.
Bt cotton is a insect resistant
transgenic crop designed to fight
the bollworm.
Bt cotton is one of the first crop
protection products from
biotechnology.
Bt cotton is a genetically modified
organism (GMO) or genetically
modified pest resistant plant, which
produces an insecticide to combat
bollworm.
Bt cotton is a insect resistant
transgenic crop designed to fight the
bollworm.
Bt-Cotton
19. Monsanto scientists inserted a toxin gene from the bacterium
Bacillus thuringiensis into cotton plants to create a caterpillar-
resistant variety.
In 2002, A joint venture between Monsanto and Mahyco introduced
Bt cotton in India.
Who invented Bt COTTON
Bt—What is It?
Bollworm larva feeding in boll
20. Mode of Action
Bt spores have to be ingested by the susceptible insect to cause mortality. The
Cry toxin becomes active by proteoletic enzymes in the alkaline gut juice (pH 7.5-
8.5).
Most cry toxins are actually pro-toxins of about 130 to 140 kDa, and after
activation, they become 60–70 kDa.
The activated toxin passes through the peritrophic membrane and binds to
specific receptors on apical microvillar brush border membrane of the epithelial
cells of the midgut making pores through which the toxin penetrates to such cells
that become swollen.
The swelling continues until the cells lyse and separate from the basement
membrane of the midgut epithelium.
21. The alkaline gut juices then leak into the hemocoel causing the hemolymph pH
rises that leads to paralysis and death of the insect.
However, it is mentioned that the naturally occurring bacteria in the
gut (E.coli and Enterobacter) penetrate to the hemocoel through the disrupted
epithelium caused by Bt toxins and multiply causing sepsis of the hemolymph
and death of the insect.
In the Bt-moderately sensitive insects, such as Spodoptera spp., the
endospore has a considerable role in killing the insect by producing toxins during
its vegetative growth in the hemolymph.
The insect or any living organism that does not have the receptors in gut
epithelial cells is not killed by Bt .
25. Major Benefits of Bt Crops
Able to withstand pest attacks.
Minimal insecticide and fertilizer required, lowering production
costs.
Increased productivity in smaller land patches.
Profitable for marginal farmers (Less than 1 ha land).
Drawbacks of Bt Crops
Seeds more expensive than conventional/common variants.
Pests may grow immune to the GM seeds.
Natural gene flow between crops is fatally sidelined.
Ethical issues.
26. Some other Bt crops examples
Bt Brinjal
Bt brinjal is also produced by genetic transformation of a
crystal protein gene cry 1 Ac from the bacterium Bacillus
thuringiensis.
Bt brinjal was developed to provide resistance against
lepidopteron insects.
The proteins produced by Bt genes bind to the receptors
present on the insect’s membrane, resulting in the formation of
pores on the membranes.
This disrupts the digestive process and leads to the death of
the insect.
29. Interfere with the digestive enzymes of the insect
Results in the nutrient deprivation causing death of the insects
According to their specificity, proteinase inhibitors (PIs) can be divided in four
classes
Serine Protease inhibitor
Cysteine protease inhibitors
Aspartic and metallo-protease inhibitors.
Bifunctional alpha-Amylase inhibitors.
Serine and cysteine-proteinase inhibitors inhibits mainly lepidopteran and
coleopteran.
Protease inhibitor
30. Most active inhibitor identified is cowpea trypsin inhibitor (Cp TI)
Transferred into at least ten other plant species.
Protein is an effective antimetabolite against a range of field and storage
pest.
CpTI-transformed tobacco, field-tested and cause significant larval mortality
of cotton bollworm.
Serine proteinase inhibitors resulted in up to 100% mortality of first-instar
cotton leaf worms when expressed in tobacco.
Protease inhibitors, therefore, form complexes with these protease enzymes
and then inhibit their proteolytic activity, in addition to protecting certain cellular
constituents, tissues and fluids
31. These recombinant inhibitors mostly act by either tightly binding
to the active site of the protease enzyme as pseudo-substrates
or would use trapping, which is a rapid conformational change
that traps the cognate protease in a covalent complex fashion
32. CASE STUDY 1
Cowpea trypsin inhibitor. The first stage in the development of cowpea
trypsin inhibitor (CpTI) as an anti-insect, pest-Control|ed mechanism came from the
identification of strains of cowpea growing in Africa that were resistant to attack
from a range of insect pests.
The isolated insecticidal protein was found against Lepidoptera, Orthoptera, and
Coleoptera.
Further tests showed that this protease isolated and inserted into transformation
vector pROK2 (a pBIN19 derivative) (Figure )
There are different ways of quantifying the extent of resistance of a plant to insect damage, either in
terms of measuring the amount of damage (loss of weight or leaf area), or assaying the effect of
eating the transgenic plant on the insect.
Both types of bioassay were used to show that lepidopteran pests tobacco budworm, cotton
bollworm, and cotton leaf worm) fed on the CpTI transgenic tobacco plants did less damage and grew
less well than those on control plants (Figure )
33. Bioassay data for feeding trials of lepidopteran pests on CpTI transgenic tobacco plants.
The activity of three different lepidopteran pest larvae (Heliothis virescens, Helicoverpa
zea and Spodoptera littoralis) on transgenic tobacco plants carrying the CpTi gene was
assayed in the laboratory in two different ways:
(a) The extent of damage to the tobacco leaves was determined by measuring the leaf
area eaten;
(b) The growth of the larvae on the tobacco was determined by measuring insect
biomass. In both assays, there was a significant protective effect from the CpTi
transgene compared with control plants. (Redrawn with permission from Gatehouse et
al. (1992)
34. Alpha-Amylase inhibitors
Insect larvae secrete a gut enzyme alpha- amylase to digest starch.
Blocking the activity of this enzyme by a-amylase inhibitor, the larvae can be
starved and killed.
a-Amylase inhibitor gene isolated from bean has been successfully transferred
and expressed in tobacco
Provides resistance against Coleoptera.
Seven types of natural proteinaceous α-amylase inhibitors have been
identified, six of which are extracted from plants, namely the knottin-like
type, the γ-thionin-like type, the cereal type, the Kunitz type, the thaumatin-like
type, and the lectin-like type.
The knottin-like type, the Kunitz type and the thaumatin-like type are able to
affect only the amylase in insects.
35. Lectins
Lectins are carbohydrate-binding proteins found in many plant tissues
Abundant in the seeds and storage tissues of some plant species
Involves specific binding of lectin to glycoconjugates located in the midgut of
the insect
Tobacco plants expressing a pea lectin were shown to be toxic to the
Lepidoptera Heliothis virescens.
Plant lectins are particularly effective against the sap sucking Hemiptera (Powell
et al., 1995). Therefore, enhancing their presence in some plant tissues may have
an insect tolerant effect.
Transgenic rice with Galanthus nivalis (snow drop) agglutinin (GNA) has shown
resistance to brown plant hopper (BPH) (Nilaparvata lugens).
37. Coat Protein Gene
Transgenic plants having virus coat protein gene linked to strong
promoter.
Tobacco, tomato, alfalfa, sugarbeet, potato etc.
First plant: 1986: tobacco, coat protein from TMV strain U1
Expression of virus coat protein gene: confers resistance to
concerned virus and gives a measure of resistance to other related
virus.
Effectiveness of coat protein: affected by amount of coat protein
produced in transgenic plants and by concentration of virus inoculum.
38. Resistance is due to blocking of process of uncoating of virus particles, which
is necessary for viral genome replication as well as expression.
GM released for commercial cultivation using CPMR
• Tomato resistant to TMV
• Tomato mosaic virus (ToMV) and cucumber mosaic virus (CMV)
• Cucumber resistant to CMV ,Squash resistant to zucchini yellow mosaic virus
(ZYMV) & watermelon mosaic virus (WMV2).
39. Produced by inverting
cDNA copy of mRNA
with respect to
promoter in an
expression vector
Antisense RNA approach
• Yields full-length
complementary copy of m
RNA sequence
• Interact with mRNA
molecules by base-pairing
to form double stranded
RNA
• Tobacco: CMV
.Potato Quality
improvement
Antisense Approach
40. Ribozyme Mediated Approach
RNA molecules that exhibit enzyme activities.
Hybrid RNA consisting of tobacco ring spot virus (TobRV) satellite RNA
endoribonuclease catalytic sequences linked to antisense RNA specific of
specific genes against they are targeted.
Strategy consists of:
Producing ribozyme specific to part of target virus genome
To produce cDNA of this ribozyme
To integrate it into host plant genome
41. Construction of expression vectors for potato transformation containing ribozyme
genes under the control of 35S promotor. R(−)D, mR(−)D, and R(+)D, tandem R(−),
mR(−), and R(+) ribozymes, respectively; nos-p, nos promotor; nos-t, nos
terminator; NPTII, neomycin phosphotransferase II; RB, right border; LB, left border.
42. References
Xicai Yang, Yin Yie, Feng Zhu, Yule Liu, Liangyi Kang, Xiaofeng Wang,
and Po Tien (1997); Ribozyme-mediated high resistance against potato
spindle tuber viroid in transgenic potatoes, jour. Proc Natl Acad Sci U S
A. 94(10): 4861–4865.doi: 10.1073/pnas.94.10.4861.
Andrian Slator, Nigel W. Scott and Mark R Fowler (2019); Plant
biotechnology the genetic manipulation of plants . Jr.Oxford, 2nd edition
pp123-285.