Chapter 6 Plant Biotechnology Plant Structure Plant Structure

Chapter 6 Plant Biotechnology

Plant Structure

Plant Structure CO 2 + H 2 O →C 6 H 12 O 6 + O 2

Agriculture: The Next Revolution v Biggest industry in the world ($1. 3 trillion of products per year) v Plant transgenesis allows innovations that are impossible to achieve with conventional hybridization methods • Resistant to herbicides • Pest resistant • Vaccines

Methods Used in Plant Transgenesis v Unique advantages of plants: • The long history of plant breeding provides plant geneticists with a wealth of strains that can be exploited at the molecular level • Plants produce large numbers of progeny; so rare mutations and recombinations can be found more easily • Plants have been regenerative capabilities, even from one cell • Species boundaries and sexual compatibility are no longer an issue

Methods Used in Plant Transgenesis v Protoplast Fusion to create plant hybrids • Degrade cell wall with cellulase • A cell lacking a cell wall is called a protoplast • The protoplasts from different species of plants can be fused together to create a hybrid • The fused protoplasts grow in nutrient agar for a few weeks • The colonies are then transferred to media to induce root and shoot growth

Methods Used in Plant Transgenesis v Ti plasmid – found in Agrobacter, a type of soil bacteria that infects plants • Integrates into the DNA of the host cell, making it an ideal vehicle for transferring recombinant DNA to plant cells

Methods Used in Plant Transgenesis v Leaf fragment Technique • Small discs of leaf incubated with genetically modified Agrobacter Ti plasmid • Treat with hormones to stimulate shoot and root development • Limitation: cannot infect monocotyledonous plants only dicotyledonous such as tomatoes, potatoes, apples and soybeans Transgenic Plant Animation

Methods Used in Plant Transgenesis v Gene Guns • Use on Agrobacter-resistant crops • Blast tiny metal beads coated with DNA into an embryonic plant cell • Aim at the nucleus or a chloroplast • Shoot in gene of interest and a gene marker (reporter)

Methods Used in Plant Transgenesis v Chloroplast Engineering • More genes can be inserted at one time • Genes are more likely to be expressed • DNA is separate from the nucleus

Methods Used in Plant Transgenesis v Antisense Technology • Flavr Savr. TM tomato introduced in 1994 • Ripe tomatoes normally produce the enzyme, polyglacturonase (PG) which digests pectin • Scientists isolated the PG gene, produced a complementary gene which produces a complementary m. RNA that binds to the normal m. RNA inactivating the normal m. RNA for this enzyme

Methods Used in Plant Transgenesis v RNA Interference (RNAi) • Inhibits gene expression by interfering with transcription or translation of RNA molecules RNAi video and animations

Practical Applications in the Field v Vaccines for Plants • Contain dead or weakened strains of plant viruses to turn on the plant’s immune system • Transgenic plants express viral proteins to confer immunity

Practical Applications in the Field v Genetic Pesticides • Bacillus thuringiensis (Bt) produces a protein that is toxic to plant pests • Transgenic plants contain the gene for the Bt toxin and have a built-in defense against these plant pests

Practical Applications in the Field v Herbicide Resistance –resistant to glyphosate

Practical Applications in the Field v Safe Storage • avidin-blocks the availability of biotin for insects v Stronger fibers v Enhanced Nutrition • Golden rice that is genetically modified to produce large amounts of beta carotene

Practical Applications in the Field v. The Future: From Pharmaceuticals to Fuel • Plant-based petroleum for fuels, alternatives to rubber, nicotine-free tobacco, etc

Practical Applications in the Field v. Metabolic Engineering • Manipulation of plant biochemistry to produce nonprotein products or to alter cellular properties

Health and Environmental Concerns v. Human Health • Allergens v. Environment • Super weeds