INSECT-RESISTANT TRANSGENIC CROPSPresented by: Ahmed MadniRegistration No.: SP14-BTY-011

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CONTENTS Transgenic crop How to develop insect-resistant plant line? Plasmid construction expressing cry1AC Benefit and risk of Bt crops Role of Bt toxins in nature Impact on non-target organisms

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INTRODUCTION Transgenic crop

Crop contains foreign gene that helps add new trait that is not possessed by wild type

That trait may be a: Resistance characterInsecticidal/Herbicidal character

Processes involved are: recDNA - recombinant DNA technologyCloning techniquesTransformation

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CONTINUED… The inserted gene sequence (known as the

transgene) may come from another unrelated plant, or from a completely different species: transgenic Bt corn, for example, which produces its own insecticide, contains a gene from a bacterium.

Bt crops include: Bt corn* Bt cotton* Bt potato Bt rice (to be introduced soon)

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TRANSGENIC PLANT DEVELOPMENT

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METHODS INVOLVED IN THE DEVELOPMENT OF TRANSGENIC CROPS Protoplast electroporation

Bombardment of plant cells with particle

Transformation - Agrobacterium tumefaciens

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PROTOPLAST ELECTROPORATION

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ELECTRIC POTENTIAL IS APPLIED

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BOMBARDMENT OF PLANT CELL WITH PARTICLES05/02/2023

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TRANSFORMATION05/02/2023

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CONSTRUCTION OF PLASMID05/02/2023

Ori-322/rop region for replication and amplification in E. coli

OriV for replication in A. tumefaciens

nptII confers kanamycin resistance.

It confers resistance to the antibiotics spectinomycin and streptomycin.

Constitutes the cry1Ac gene expression cassette

The initiation point for the transfer of T-DNA from A. tumefaciens to the plant genome

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BENEFITS AND RISKS OF BT CROPS

Benefits Reduced pesticide use over 80% Increased yields by several percent Crop loss is reduced due to pest damage No environmental effects as compared to pesticides

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CONTINUED…Risks o The reliability of substantial equivalence Same sequence of encoded protein to its natural one

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CONTINUED… Transfer of transgenes from transgenic plant to wild

relatives or bacteriaTransfer of resistant gene to organisms and make it resistant. Transformed wild plant have negative environmental impact by killing beneficial insects and soil.

Solution - Selectable marker can be used instead of antibiotic resistant gene.

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ROLE OF BT TOXINS IN NATURE It contributes to the reproductive fitness of the

bacteria Its specificity to particular nematodes Realistic levels of Bt toxins leads to certain changes

in soil biota

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IMPACT ON NONTARGET ORGANISMS Depending upon receptor- specificity is there A report lists 376 lepidopteran species as feeding

on Zea mays (corn) Of these, fewer than 15 are believed to have been

tested for susceptibility to the Bt toxins expressed in GM corn

Nontarget species that depend on Zea mays as a host plant or that consume corn pollen may be important as plant pollinators for other plants.

Negative impacts on the populations of such insect species may not be readily noticed.

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Thank you

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