Transformation is the genetic alteration of a cell resulting from the direct uptake, incorporation and expression of exogenous genetic material (exogenous DNA) from its surroundings and taken up through the cell membrane(s).Transformation can be used to describe the insertion of new genetic material into nonbacterial cells, including animal and plant cells. AGROBACTERIUM MEDIATED TRANSFORMATION Agrobacterium mediated transformation is the easiest and most simple plant transformation. Plant tissue (often leaves) are cut into small pieces, e.g. 10x10mm, and soaked for 10 minutes in a fluid containing suspended Agrobacterium. Some cells along the cut will be transformed by the bacterium, that inserts its DNA into the cell. Placed on selectable rooting and shooting media, the plants will regrow. PARTICLE GUN METHOD Particles of gold or tungsten are coated with DNA and then shot into young plant cells or plant embryos. Some genetic material will stay in the cells and transform them. This method also allows transformation of plant plastids.