The bacterium having the vector with the desired gene is put in the media having the sterilized and freshly cut plant explant which may be colyledon, leaf, hypocotyl, or stem meristem. The bacteria is able to transfect the explant cells after which the medium is treated with antibiotics to phase out bacterial cells.

Transformed Cell Selection

Transformed plant cells are selected based on several strategies such as identification based on selection of marker genes inserted into the transformation vectors.

Growth and Regeneration of Plantlets

Media composition and culturing conditions are altered to encourage growth of only transformed cells. Such cells are then manipulated to undergo organogenesis for plantlet regeneration. Shooty or rooty cultures are formed depending on whether the gene insertion has replaced the auxin or cytokinin loci on the phytohormone gene.

Lab to Field Passage

Plantlets so formed are carefully transferred from media to very small lots of sterilized soil samples under appropriate lighting and other conditions within the laboratory in an area earmarked for such nursing protocols. After a certain period of acclimitization based on the plant species, the tended saplings are shifted to green house conditions with close supervision. After observation under such controlled conditions, further grown plantlets are finally transferred to the field.

Though initially applicable only to dicots, today the technique may be used even with monocots by adding phenolic compounds, such as acetosyringine, that act as inducers of vir-genes, to the cultivation medium having both the bacteria and plant cells. These compounds elicit wound response in the explant thus enabling infection of the monocot cells by the bacterium and so even transformation.

Plant viruses capable of introducing their genome into plant cells can be used for generating transgenic plants of vegetatively propagated plants. Today several chemicals are known to induce DNA uptake by plant cell protoplasts. Also many mechanical methods of DNA transfer into plant cells such as electroporation, microinjection, and particle bombardment, are added to the arsenal of gene transfer methods.