How to make genetically engineered plants

Summary

This video explores the strategies used to create genetically engineered plants, focusing on two primary methods: the use of agrobacterium and particle bombardment (gene gun). Agrobacterium, a soil bacterium, naturally transfers DNA into plant cells, which can be modified for genetic engineering. The gene gun method uses gold or tungsten particles coated with DNA to deliver genetic material into plant cells. Both methods rely on plant tissue culture techniques to regenerate full plants with new genetic traits. The video also touches on genetic modification labeling, highlighting USDA organic versus non-GMO labels.

Takeaways

• 😀 Agrobacterium is a naturally occurring bacterium found in soil that can transfer DNA into plants, causing crown gall formation.
• 😀 Agrobacterium's plasmid contains genes that help it infect plants, including regions for replication, virulence, and opine synthesis.
• 😀 The T-DNA region of agrobacterium’s plasmid can be modified to introduce new genes into the plant’s genome.
• 😀 Particle bombardment (or gene gun) involves shooting DNA-coated beads into plant cells to introduce new genetic material.
• 😀 After DNA introduction, plant tissue must be regenerated into full plants using hormones like auxin and cytokinin.
• 😀 Callus tissue, which is undifferentiated plant tissue, is crucial for regenerating plants from transformed cells.
• 😀 A selectable marker, like an antibiotic or herbicide resistance gene, ensures that only transformed cells are selected during regeneration.
• 😀 Protoplasts, plant cells with their cell walls removed, can be used for transformation through electroporation, allowing DNA entry into the cell.
• 😀 The gene of interest is introduced into protoplasts using an electric current, which causes the cell membrane to open and allow DNA integration.
• 😀 USDA Organic certification ensures that products have been grown without synthetic chemicals or GMOs, while the Non-GMO Project Butterfly label is a paid verification without significant regulatory or growing practice implications.

Q & A

What is Agrobacterium and how is it involved in genetic engineering of plants?

Agrobacterium is a naturally occurring soil bacterium that transfers DNA into plant genomes. This process is used in genetic engineering to introduce specific genes into plants, making them transgenic. The bacterium naturally causes crown galls in plants, which can be exploited to insert desired genes into the plant's DNA.

How does Agrobacterium transfer DNA to a plant?

Agrobacterium transfers DNA through a plasmid that contains a transfer region (T-region). The T-region DNA is introduced into the plant's genome, where it integrates and can cause the plant to produce food and hormones that benefit the bacterium.

What is the significance of the T-region in Agrobacterium’s DNA?

The T-region is the part of the Agrobacterium plasmid that is transferred into the plant’s genome. It contains genes for opine production (which the bacterium uses as food) and genes that affect plant hormone production, leading to tumor-like growths known as crown galls.

What is particle bombardment, and how is it used in genetic engineering?

Particle bombardment, also known as biolistics or the gene gun, is a method used to introduce foreign DNA into plant cells by firing small gold or tungsten particles coated with DNA into the plant cells. The DNA can then integrate into the plant's genome, resulting in a genetically engineered plant.

How does the gene gun work in genetic transformation?

The gene gun uses a high-pressure blast to shoot DNA-coated metal particles into plant tissues. The goal is to have these particles, carrying the foreign DNA, penetrate the plant cell walls and membranes, ideally reaching the nucleus where the DNA can integrate into the plant's genome.

What is a callus in plant tissue culture, and why is it important for genetic engineering?

A callus is a mass of undifferentiated plant cells that can be regenerated into various plant tissues. In genetic engineering, callus tissue is important because it provides a pool of cells that can be manipulated to regenerate plants that carry the desired genetic modification.

What role do plant hormones like auxin and cytokinin play in plant tissue culture?

Auxin and cytokinin are plant hormones used in tissue culture to guide the differentiation of callus cells into different plant tissues. By adjusting the ratio of these hormones, scientists can induce the growth of roots, shoots, or leaves from undifferentiated callus tissue.

How is a selectable marker used in plant genetic engineering?

A selectable marker is a gene introduced into the plant’s genome alongside the gene of interest. It helps identify cells that successfully integrated the new DNA. Common markers include antibiotic or herbicide resistance, allowing only the transformed cells to survive and grow.

What is electroporation, and how does it contribute to plant transformation?

Electroporation is a technique where an electric current is used to temporarily open the pores of plant cells or protoplasts (cells without cell walls). This allows foreign DNA to enter the cells, where it may integrate into the plant’s genome, enabling genetic modification.

What is the difference between USDA Organic and Non-GMO Project Verified labels?

The USDA Organic label certifies that the product has been grown without synthetic pesticides or genetically modified organisms (GMOs), among other requirements. The Non-GMO Project Verified label, however, only indicates that the product does not contain genetically modified organisms, without guaranteeing organic or chemical-free growing practices.