Overview of GMO

A plant, such as corn or soybean, is considered genetically modified when genetic material from outside of that organism is inserted into its DNA sequence. Plants grown from seed harvested from genetically modified plants will also contain the genetic modification. To date, the most common genetic modifications in crops confer an herbicide or an insect resistance to the plant. This resistance is achieved through production of a novel protein encoded by the inserted DNA sequence.

In plants that are genetically modified for commercial agricultural purposes, the recombinant sections of DNA that are artificially inserted into the natural plant genome have some common genetic elements. Each inserted DNA sequence consists of at least a promoter, a protein-coding site (the structural gene) and a terminator. The promoter is a sequence of DNA that acts like an "on switch" for the transcription of DNA into mRNA, the first step in the activation of the cell's protein producing tools. The terminator marks the end point for this transcription procedure. The structural gene determines the particular protein that is to be made.

The 35S promoter in the genetic modification present in Roundup Ready soy is derived from the cauliflower mosaic virus. The novel protein that confers resistance to Roundup is EPSPS taken from the soil bacterium Agrobacterium tumefaciens. The Nos-terminator used in the Roundup Ready soybean's GM construct originates from A. tumefaciens as well.

Genetically modified (GM) crops are increasingly being introduced into the world's food supply. Concerns raised by consumers and regulatory agencies in various countries have highlighted the need for reliable and accurate testing for the presence and the amount of genetically modified components.

Techniques Applicable to GMO Testing

The challenge facing a testing laboratory is to recognize an artificially inserted sequence of DNA, determine the amount of that material present and identify the specific modification present. Currently, there are two different general approaches used to detect genetically modified materials.

ELISA (enzyme linked immunosorbent assay) is designed to detect the presence of the novel protein encoded by the inserted DNA sequence.

» Read more about ELISA

PCR (polymerase chain reaction), a powerful and common molecular biology technique that can detect the actual DNA sequences that have been inserted.

» Read more about PCR

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