Figure 1. Transformation and regeneration of plants. Many plant organs, tissues or cell types can be used for transformation, the choice of which is determined by the plant species and/or the transformation method. After transformation, plant cells that integrated the transgene are selected, propagated and transgenic plants are regenerated.

Figure 2. Scheme of Agrobacterium tumefaciens-mediated gene transfer. (1) Wounded plant cells release their content; (2) agrobacterium senses phenolic compounds leading to the activation of virulence genes; (3) the action of some virulence proteins directly on the T-DNA results in the formation of a complex consisting of a single stranded T-DNA attached to the VirD2 protein (represented by a black circle) and possibly coated by VirE2 proteins (represented by a grey oval); (4) the T-complex is exported to plant cells and (5) enters the nucleus; (6) T-DNA is integrated randomly in the plant nuclear genome.

Figure 3. Schematic representation of the principle of a particle bombardment device.

Figure 4. Importance of transgenic crops in agriculture. (a) Major traits for which plants have been genetically modified (data from 2000). (b) Cultivation of genetically modified plants in the USA, Argentina and Canada between 1996 and 2000.