In this way both parts of the project can move forward simultaneously. The gene transfer process will actually be carried out by a bacterium called Agrobacterium tumefaciens , a natural genetic engineer. Wild-type Agrobacterium lives in the soil and invades small wounds near the root collar of many plant species, including chestnut. The DNA travels to the nucleus and is incorporated into the chromosomes of the plant. The bacteria then live and multiply happily inside the gall.
Bacteria are much easier to manipulate than plant cells.
The final step is to regenerate whole plants from the transformed cells. At the tip of every growing shoot is a region of a few cells called the apical meristem. These cells are unique in that they grow and divide very rapidly and are capable of producing all the above-ground portions of a plant. We are now attempting to cut thin slices through the tips of tiny chestnut shoots and transform them with Agrobacterium . We know that we can regenerate new shoots from these shoot tip slices, but we do not know yet if the Agrobacterium can successfully transform them.