Lecture 9 &10

InsectInsect resistant plantsresistant plants

Genetic engineering of plants Genetic engineering of plants and applicationsand applications

Agriculture Transgenics On the Market

Source: USDA

Insect resistant cotton – Bt toxin kills the cotton boll worm• transgene = Bt protein

Insect resistant corn – Bt toxin kills the European corn borer• transgene = Bt protein

Normal Transgenic

Plasmid carrying the potato Plasmid carrying the potato proteinase inhibitor II geneproteinase inhibitor II gene

α- amylase inhibitor α- amylase inhibitor genegene

• amylase inhibitor - seed proteins of the common beanamylase inhibitor - seed proteins of the common bean• the gene for the α -amylase inhibitor isolatedthe gene for the α -amylase inhibitor isolated• under the transcriptional control of the strong seed-under the transcriptional control of the strong seed-

specific promoter for the bean phytohemagglutinin specific promoter for the bean phytohemagglutinin gene gene

• transform pea plants (Pisum sativum)transform pea plants (Pisum sativum)• Peas susceptible to cowpea weevils and azuki bean Peas susceptible to cowpea weevils and azuki bean

weevilsweevils• transgenic pea plants that expressed the α -amylase transgenic pea plants that expressed the α -amylase

inhibitor resistant to both of these insects inhibitor resistant to both of these insects

Bacterial cholesterol Bacterial cholesterol oxidase geneoxidase gene

• Cholesterol oxidase, present in different bacterial generaCholesterol oxidase, present in different bacterial genera

• catalyzes the oxidation of 3-hydroxysteroids to ketosteroids catalyzes the oxidation of 3-hydroxysteroids to ketosteroids and hydrogen peroxide and hydrogen peroxide

• high level of insecticidal activity against larvae of the boll high level of insecticidal activity against larvae of the boll weevil (weevil (Anthonomus grandis grandisAnthonomus grandis grandis))

• acts by disrupting the insect’s midgut epithelial membraneacts by disrupting the insect’s midgut epithelial membrane• cloned into a vector under the control of a plant virus (figwort cloned into a vector under the control of a plant virus (figwort

mosaic virus) promoter mosaic virus) promoter

• targeted to the tobacco protoplasts, the transformed cells targeted to the tobacco protoplasts, the transformed cells actively expressed the cholesterol oxidase gene proving to be actively expressed the cholesterol oxidase gene proving to be insect resistant transgenic plantinsect resistant transgenic plant