Summary - Transformation

  • Transformation is when a new gene (transgene) is delivered into the nucleus of a plant cell and inserts into a chromosome where it is passed on to progeny.  
  • Transformation is typically done on callus cells (tissue culture) but is occasionally done to other plant parts, such as germline cells or pollen.  
  • The four main methods of transformation are:
    1. Gene gun - shoots gene-coated gold particles at cells
    2. Agrobacterium - a natural genetic engineer that inserts a portion of the Ti plasmid containing a transgene
    3. Whiskers - gene-coated needles that stab the cell
    4. Electroporation - Pulses of electricity open pores in the cell wall allowing genes to pass into the nucleus
  • The goals of the transformation process are:
    1. Deliver many copies of the gene(s) into the nucleus without killing the cell
    2. At least one transgene copy must insert into a chromosome (can't be controlled by the geneticist)
    3. Transgenic cells must replicate their chromosomes and divide, passing the transgene on to progeny
    4. There must be a way to easily identify and select the transgenic cells from non-transgenic cells (use of a selectable marker gene)