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Selection

Selection of succesfully transformed plants

Selection is a general principle of evolution, wherby the most fit organisms survive and pass on their genes.

In relation to transgenic plants: Following transformation, regenerated plants are identified in which transformation has been successful. In other words, plants are selected that have integrated the foreign genes in their plant genome.

However, since in most cases, the foreign gene does not cause a visual change in the transgenic plant, a selection marker is used. This enables the successfully transformed plants (only a very small percentage) to be selected.

The main selection markers currently used to select transformed cells are antibiotic-resistance and herbicide-resistance genes. They are introduced into the plant alongside the actual target gene.

If an antibiotic resistance marker gene is used, for example, the antibiotic will be added to the medium that is used to regenerate plants after the genetic transformation procedure. The antibiotic will kill the cells that did not successfully take up the marker gene and the gene of interest. In contrast, the transformed, resistant cells will grow without a problem into entire transgenic plants. One alternative method enables selection by using physiological markers that affect the transformed cells’ metabolism.