MANOJ B.S

15MSABC005M,Sc. AGRI BIOCHEMISTRY.JSBB. SHIATS,ALLAHABAD.

SAM HIGGINBOTTOM INSTITUTE OF AGRICULTURE, TECHNOLOGY AND SCIENCES

CONTENT

INTRODUCTION ABOUT Bt.

Bt. COTTON

WORKING MECHANISM OF Bt.

ADVANTAGES AND DISADVANTAGES OF Bt. COTTON

Bt. BRINJAL AND ITS PRODUCTION TECHNIQUES

ADVANTAGES AND DISADVANTAGES OF Bt. BRINJAL

Bt. CORN AND ITS BENEFITS.

Shigetane Ishiwatari (1901), first isolated Bacillusthuringiensis.

Bt is commonly abbreviated as Bacillus thuringiensis,is a gram-positive, facultative aerobic, rod-like,motile and sporulating bacterium.

Bt is a naturally-occurring soil borne bacterium thatis found worldwide

Ubiquitous in nature.

Produces crystals of endotoxin (Cry protien or deltatoxin) - toxic to insect mainly in their larval stage,thus they act as insecticides.

Bacillus thuringiensis

These crystal proteins (Cry proteins) are insectstomach poisons

Insects stop feeding within two hours of a firstbite and, if enough toxin is eaten, die within twoor three days

Important biological insect control agent.

Bt crystals, sometimes referred as insecticidal crystalproteins (ICP), are protein crystals formed duringsporulation in some Bt strains coded by cry genes.

What is Bt cotton ?

• Genetically modified variety of cotton

that produces an insecticide.

• Marketed by Monsanto, USA.

HOW Bt WORKS ?

1. Ingestion

2. Solublization & proteolytic activation

3. Binding to target site

4. Formation of toxic lesions

Mode of action of Cry toxin

Epithelium

Dissolving of crystals and activation of toxins

Pro-toxin

Activated ∂- endotoxin

Receptors

Toxins bind to receptors

Perforation of gut membrane

Crystals

Hilbeck and Schmidt (2006)

Fig 10: Mode of Action of Bt Toxin in Insect Gut

TECHNOLOGY OF PRODUCTION

• Main steps for developing transgenic crops :

1. Identification of effective gene(s).

2. Gene transfer

3. Regeneration from protoplast/callus/tissue

4. Gene expression to the desired level

5. Back cross to produce varieties

6. Field test

7. Approval for commercialization

METHODS OF GENE TRANSFER

• Agrobacterium mediated gene

transfer

• Bombardment of cells with

particle coated with gene of

interest

Transformation with Agrobacterium

• Agrobacterium contains a circle

of DNA (Ti plasmid) that carries

the desired genes

• Co-cultivation of the

Agrobacterium with plant pieces

transfers the DNAPetri dish with leaf pieces & Agrobacterium

Bt cotton in India

• India is the largest cotton producer and consumer country

after China.

• In 2002 Bt cotton was introduced in India.

• India has the largest hectarage of cotton and accounts for

approximately one third of the total cotton are planted in the world.

• Cotton yield increased from 308kg/ha in 2001-02 to

550kg/ha in 2014-15.

Advantages of Bt-cotton

• Yield superiority

• More profit

• Lesser need of pesticide

• Better quality

• Suitability for early sowing

DISADVANTAGES

• Higher cost of seeds

• Higher fertilizer and irrigation cost

Trade name Bt protein crop Company Insect pests

Bollgard Cry1Ac Cotton Monsanto Tobacco budworm,

cotton bollworm,

pink bollworm

Bollgard II Cry1Ac+Cry2Ab Cotton Monsanto Tobacco budworm,

cotton bollworm,

pink bollworm

Widestrike Cry1Ac+Cry1Fa cotton Dow Tobacco budworm,

cotton bollworm,

pink bollworm

List of transgenic cotton (Bt cotton)

Commercial release of different Bt cotton events in India, 2002 to 2009

No. Event Developer Status Date of approval

1 MON-531 Mahyco/Monsanto commercialized 2002

2 MON-15985 Mahyco/Monsanto commercialized 2006

3 Event-1 JK Agri-Genetics commercialized 2006

4 GFM Event Nath Seeds commercialized 2006

5 BNLA-601 CICR (ICAR) & UAS,Dharwad

commercialized 2008

6 MLS-9124 Metahelix Life Sciences commercialized 2009

Future prospects of Bt cotton in India

• 5 new hybrid cottons are under biosafety assessment which will

be considered for commercial approval between 2013-15.

• . Other traits include drought and salinity tolerance, disease

resistance, sucking insect resistance, leaf curl virus resistance

and other traits related to cotton fiber quality.

Bt. BRINJALBrinjal is botanically known as Solanum melongena L. (2n =24) included under the genus Solanumwhich is one of the largest genera having more than 1,500 described plant species.

The cultivated types are fit for human consumption and are divided into three main varieties basedon fruit shape.

S. melongena var. esculentum(Round or egg-shape)

S. melongena var. serpentinum(Long and slender)

S. melongena var. depressum(dwarf brinjal plants)

MAJOR PROBLEMS

• Major problem in brinjal cultivation is brinjal shoot and fruit borer (Leucinodes orbonalis).

• It is monophagous and attacks all aerial parts of plant specially shoot and fruit.

• Damage the fruit and affect fruit quality badly.

• It causes yield losses about 60-70% even after multiple insecticide spray.

EGGS

LARVAE

PUPAE

ADULT

25-43 days

Fig 6: Life Cycle of The Fruit and Shoot Borer

SHOOT DAMAGE FRUIT DAMAGE

Symptoms of Damage

Bt Brinjal is a transgenic brinjal created out of inserting a gene [cry IAc] from thesoil bacterium Bacillus thuringiensis in to brinjal.

The insertion of the gene into the Brinjal cell in young cotyledons has been donethrough an Agrobacterium mediated vector, along with promoters, markers etc.

This is said to give the Brinjal plant resistance against lepidopteran insects like theBrinjal Fruit and Shoot Borer (Leucinodes orbonalis) and Fruit Borer (Helicoverpaarmigera).

It is reported that upon ingestion of the Bt toxin by the insect, there would bedisruption of digestive processes, ultimately resulting in the death of the insect.

1 INOCULATION

2 CO-CULTIVATION

3

4

5

6SELECTION & REGENERATION

RE-GROWTH

MOLECULAR VERIFICATION OF GENEPRESENCE & EXPRESSION

EVALUATION OF TRANSFORMED BRINJAL PLANT FOR INSECT PROTECTION

• 60% of plant protection cost for controlling fruit and shoot borer isreduced.

• In spite of the extensive use of chemical pesticides, larvae lead aconcealed life, it is difficult to control through insecticide sprays.

Arguments in Favour of Bt Brinjal

WHAT ARE THE BENEFITS OF Bt BRINJAL.?

1) non-infested, undamaged and good quality brinjal fruits.

2) Bt brinjal will significantly reduced level of pesticide residues,

Farmers are expected to benefit at multiple levels. Some of these include:

3) Saving on cost of insecticides and lower labor cost as a result of reduced

spraying.

4) Increase in yield per unit area by saving fruits from damage caused by FSB.

Non-Bt. Non-Bt.

Benefits to Farmers

Bt.

Bt. CORN

Why does corn need protection from corn

borers?

Each year, 40 million tons of corn never reach the

market due to damage.

If corn borers are not controlled, the larvae will

eventually turn into moths and the cycle continues.

Bt corn produces a protein that gives Bt corn built-

in resistance to the corn borer – offering protection

throughout the plant where the insect attacks.

HOW DOES Bt. CORN WORK?

Bt maize has built-in protection against corn borers, achieved through

modern biotechnology, where the Cry1Ab gene has been added.

The Cry1Ab gene produces a Bt protein (Cry1Ab) which protects the plant

from insect damage (Bacillus thuringiensis )

Stalk tunnel after infectionTunneling of borer

What are the benefits of Bt corn?

It represents an environmentally sustainable way to control devastating insect pests and, therefore, to ensure yield.

Also, grain from Bt corn is often of better quality than grain from conventional corn hybrids, since insect damage reduces grain quality.

Studies show that there is a significant economic return from growing Bt corn, with yields protected in years when there is a heavy outbreak of corn borer.

There is also evidence that Bt corn provides a form of protection to non-Bt corn by reducing the overall population of corn borers

Expected benefits are based on the following assumptions

• Bt corn (MON810, BT11) provides 96% average control of European corn borer larvae,

• Bt corn (event 176) provides 96% control of first generation corn borers and 75% control of second generation corn borers.

• Insecticides provide 80% and 67% control of first and second generation borers, respectively.

Does Bt corn affect beneficial insects and natural enemies?

Many studies have shown that Bt Cry proteins are highly selective in killing larvae of moths.

Bt corn, however, does not affect beneficial insects including honey bees, lady beetles, green lacewing larvae, spiders, pirate bugs or parasitic wasps .

Indirect effects on natural enemies of European corn borer, however, could occur.

Predators, parasites and pathogens of the corn borer might decline as corn borer populations decline.

Bt has no toxic impact in higher animals (HUMAN) because of…..

• Acidic stomach

• Very low pH (∽1.5 in humans)

• Absence of required receptors

Bt is safe to non-target organisms-

HUMAN

1Hilbeck and Schmidt (2006).

2. Anonymous, 2009

3. Choudhary & Gaur, 2009

4. Bravo A., Gill S. S., & Soberon M. (2007). Mode of action

of Bacillus thuringiensis Cry and Cyt toxins and their potential

for insect control. Toxicon, 49(4), 423-435

5. Aronson, A. (2002). Sporulation and δ-endotoxin synthesis

by Bacillus thuringiensis. Cellular and Molecular Life

Sciences CMLS, 59(3), 417-425.