Genetic Modification

Genetic Modification



Genetic Modification

A1. Relation of Issue to System

Genetic modification allows plants to be produced with specific qualities more accurately and efficiently than through traditional methods such as cross-breeding to produce hybrid plants1. Through cross-breeding, large amounts of genetic material are passed between plant varieties. This makes it more difficult to develop specific characteristics without incorporating other unwanted ones, such as susceptibility to disease2. GM technology is being developed to create crops with characteristics such as added nutritional value, herbicide tolerance, and pest resistance.

Plants have a great practical advantage over animals in terms of their suitability for genetic modification. Their cells are totipotent, i.e. they have the potential to become any other cell in the plant, and you are able to regenerate an entire plant from a single cell.

A2. Scientific Perspective

There are many methods used to insert genes into plants, the two main ones being soil bacteria and the gene gun. The 'gene gun' or 'biolistics' method can be used with all plant species, but is used mainly with cereals. Tiny gold or tungsten particles, coated with DNA, are fired into plant tissue5. The most common method of transferring genes to plant cells is to use Agrobacterium tumefaciens. In nature this soil bacterium infects plants and causes tumors called crown galls. The tumors are induced by a plasmid in the bacterium called the Ti plasmid, which has the ability to invade plant tissue and insert part of the plasmid (called T-DNA) into the plant genome. Scientists have been able to delete the gene necessary for gall formation while retaining the genes needed to infect host cells (Shewry 1999).

The modified plasmid is then transferred into the bacterium and the bacterium allowed to infect the target plant cells. The T-DNA region of the plasmid (containing the new gene and the antibiotic resistance gene) enters the plant cell nucleus and is incorporated into the plant genome. The plant cells are then grown in culture in the presence of the antibiotic for which the modified T-DNA carries a resistance gene. Only those cells into which the T-DNA has been successfully inserted will survive in the antibiotic. This provides a good method for selecting successfully transformed cells, which can then be cultured into whole plants. Agrobacterium transformation has proven highly successful and has been used in producing transgenic plants from a range of species including tobacco, tomato, cotton and apple (Nakase 1996).

B. Explanation of Two Viewpoints

In current ethical discussions about genetic modification the notion that animals and plants have intrinsic value has become an important concept. It maintains that they are significant in themselves before any use to which humans may put them. This goes beyond the 'cost versus benefit' approach to weighing animal suffering against human benefit. It argues that some things should not be done using animals, not because of what they feel but because of what they are. How far should this way of thinking influence the more functional views typically held by researchers? Should it also apply to plants ...