Introduction - Gene Constructs
The previous lesson about gene regions discussed the 3 regions of a gene (gene construct). Genetic engineers modify the construct of a gene by replacing one or more regions. Combining different promoters and coding regions gives genetic engineers many possibilities for designing a gene that will express in a desired way once inserted into a plant.
In the previous lesson, three different coding regions for the Bt trait were also discussed. Genetic engineers have used both the 35S and PEP carboxylase promoters with the different coding regions to obtain different trait expression. The 35S promoter has been used in conjunction with the Cry 1A(b) coding regions resulting in the production of the Cry 1A(b) Bt protein in all cells all of the time. The 35S promoter has also been used with the Cry 9C coding region to produce a different Bt protein (also lethal to the ECB) in all cells all of the time.
Combining different gene regions is not limited to the Bt trait. Genetic engineers have used this technique to develop Roundup resistant and Liberty resistant crops. Later in this lesson the gene construct and expression of those traits will be explained.