Title: Unit 10 Reading and Multimedia Assignment
Course: SAT 170 Introductory Biotechnology > Section: SAT 170 Introductory Biotechnology

Unit 10 Reading and Multimedia Assignment

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“Biotechnology in Agriculture," by Boundless, CC BY SA 3.0

https://www.boundless.com/biology/biotechnology/biotechnology-and-everyday-life/biotechnology-in-agriculture/

Reading Assignment: Biotechnology in Agriculture
Transgenics allows scientists to generate plants and animals that possess specific traits by introducing foreign genes into the genome.

Transfer of T-DNA into plant cell by Agrobacterium tumefaciens
A: Agrobacterium cell
B: Agrobacterium DNA
C: Ti Plasmid
D: Plant cell
E: Plant mitochondria
F: Plant chloroplast
G: Plant nucleus

Application: Genes can be transferred from one plant to another using a vector. Genes that cause herbicide resistance, delayed ripening, pest resistance and increased nutritional value are all genes that may be beneficial if added to plant.

Technique:
1. T DNA is the segment of a Ti plasmid that can insert itself into host chromosome. Ti plasmid is isolated from Agrobacterium tumefaciens soil bacteria.
2. The gene of interest is placed into the middle of the T DNA segment of the Ti plasmid.
3. The plasmid is now recombinant. The plasmid can be introduced to the plant cell through electroporation, or the plasmid can be re-inserted into the bacteria. The plant is then infected by placing a liquid suspension of the recombinant bacteria onto the leaves of the plant. After the plasmid enters the plant, the T DNA will be integrated into the plant genome.

Results: Cells that have the transgene can be used to form new adult plants that will express the inserted gene, and have the new, desirable trait.

- For thousands of years, humans have been trying to improve or select certain traits in plants and animals through selective breeding.
- Transgenic animals are created in order to produce desirable traits in the livestock. In some instances, the cloned gene may be transferred to a different breed or species. However, increased diseases and decreased fertility are often seen when gene transfer between species occurs.
- Plants are also manipulated. Genes for traits, such as disease resistance and delayed ripening, have been added. Plants are easier to clone because a whole plant can be created from a fully differentiated adult cell.
- Genes are most often introduced into plants with Ti plasmids, which are from the soil bacterium Agrobacterium tumefaciens. The wild type A. tumefaciens will cause disease, but the A. tumefaciens used as a vector does not cause disease.
- The Ti plasmid works by inserting a piece of its DNA, called T DNA, into the host cell's chromosome.
- Plant breeding programs are being phased out with genetic engineering of plants.

Genetic engineering is actually a very old concept. For thousands of years, humans have been attempting to produce plants and animals that possess specific traits or produce more of a certain product. Selective breeding is the process of breeding plants and animals for particular genetic traits.

Today, technology is allowing scientists to generate these organisms more quickly by using transgenics. A transgenic animal is one that carries a foreign gene that has been deliberately inserted into its genome. The foreign gene is constructed using recombinant DNA methodology. In addition to the gene itself, the DNA usually includes other sequences to enable it to be incorporated into the DNA of the host and to be expressed correctly by the cells of the host. It is a more extreme methodology, but in essence, it is not really different from crossbreeding or genetic selection in its result — the main difference is in the rate of change in the animal.

Transgenic livestock can be created to produce desirable traits that are useful commercially Genes can be inserted into livestock to help them grow faster, improve meat composition, produce more milk, or make better quality wool. Other practical applications of transgenic research in livestock production include improved reproductive performance, increased feed utilization and increased disease resistance. However, some species have shown decreased fertility and an increased susceptibility to disease when genes are transferred between species.

Transgenics is also used on plants, which are often easier to manipulate since an entire plant can be created from a single, differentiated adult cell. Crops containing genes that will enable them to withstand biotic and abiotic stresses may be developed. For example, drought and excessively salty soil are two important limiting factors in crop productivity. Biotechnologists are studying plants that can cope with these extreme conditions in the hope of finding the genes that enable them to do so and eventually transferring these genes to the more desirable crops. One of the latest developments is the identification of a plant gene, At-DBF2, from thale cress, a tiny weed that is often used for plant research because it is very easy to grow and its genetic code is well mapped out. When this gene was inserted into tomato and tobacco cells (see RNA interference), the cells were able to withstand environmental stresses like salt, drought, cold and heat far better than ordinary cells. If these preliminary results prove successful in larger trials, then At-DBF2 genes can be used to engineer crops that can better withstand harsh environments. Researchers have also created transgenic rice plants that are resistant to rice yellow mottle virus (RYMV). In Africa, this virus destroys a majority of the rice crops and makes the surviving plants more susceptible to fungal infections.

Genes are most often introduced into plants using Ti plasmids. Ti plasmid is a circular plasmid that often, but not always, is a part of the genetic equipment that Agrobacterium tumefaciens and Agrobacterium rhizogenes use to transduce its genetic material to plants. They work by inserting a piece of DNA, called T DNA, into the chromosome of the host cell. The Ti plasmid is lost when Agrobacterium is grown above 28°C. Such cured bacteria do not induce crown galls (i.e., they become avirulent), so they can be used as a vector without inducing the disease (Figure 0). The genetic engineering of plants has been so successful that in many areas it is phasing out plant breeding programs. Genetically modified seeds for a variety of crops are now commercially available all over the world.