Agricultural Biotechnology Support Project II

Supporting agricultural development through biotechnology

Product Research

The first steps in developing a bio-engineered product involve isolating and characterizing the genes that are needed to produce the desired traits in the organism. This may be as simple as identifying the correct Bt toxin to control an insect pest or the much more complex process of modifying the nutritional content of a staple. The genes need to be placed into appropriate constructs – linked to promoters which control when the gene is expressed and often to a selectable marker to aid the transformation process.

The transformation process involves getting the genetic construct stably integrated into the host cell genome and then regenerating an intact organism from the transformed cells. Depending on the species and often strain of the organism selected this process may involve a vector organism – such as the soil bacterium Agrobacterium tiumefaciens – or direct introduction of the gene construct using physical means such as a “gene-gun”.

The transformation process is usually only very slightly successful in that very few of the treated cells actually contain the integrated genes. Thus there is a need to select only the transformed cells and to regenerate intact organism from these cells only. This entails the use of selectable marker genes which give the transformed cells the ability to grow while untransformed cells do not. Commonly, this is by the use of resistance to an antibiotic or a herbicide, but genes which allow the utilization of an uncommon substrate are also used to give the transformed cells a selective advantage.

Regenerating an intact organism from the transformed cells involves tissue culture techniques and – again depending on the species and strain transformed – can take a significant amount of time and expertise. At this stage, molecular characterization of the regenerated individuals is necessary and a number of separate transgenic “events” are selected based on the desired expression of the transgene. Further development of these elite events is then required to develop products.