Locating Genes for Plant Traits

In the transgenic process, the most limiting step is identifying and locating genes for certain desired traits. Traits of interest include helping to enhance yield potential (amount of product), improve stress tolerance and to modify chemical properties of the harvested product. Not only must scientists identify certain genes, but they must also know how it interacts with other genes that are active in the same biochemical pathway. A few changes to the isolated gene must be made for it to be successfully inserted into the plant.

First off, a promoter sequence must be added to the gene. This sequence acts as an on/off switch that control where the gene is expressed. these genes must also sometimes be modified. For example, the Bt gene for insect resistance has a greater amount of A-T nucleotide pairs than plants, which tend to have more C-T pairs. The A-T nucleotides can be substituted for with C-T pairs in a way that doesn't quite change the amino acid sequence. This leads to a greater protection of the inserted gene in plant cells. A terminal sequence must also be added to signal when the end of the gene sequence has been reached. Lastly, a selective marker gene is inserted in order to identify plant cells which have successfully integrated the transgene.

Fig. 2