These are then fired from a special gun into the layer of cells taken from the receiving plant. Some of these pellets may pass through the nucleus of a cell and put down their package of genes, which from there it may integrate with the cell's own DNA. .
Since the methods used to transfer genes have an exceedingly low success rate, scientists need to find which cells have taken up the novel DNA. Thus, before the gene is transferred a marker gene is attached, which codes for resistance to an antibiotic. Plant cells, which have been engineered, are then grown in a place containing this antibiotic, and only the ones that survive are those that have taken up the new genes with the marker attached. These are then cultured and grown into fully developed plants. Furthermore, a promoter is also inserted along with the new gene in order to switch it on in its host. A promoter that often force genes to express their traits at very high levels, also have the potential to influence neighboring genes. The promoter, for example, accelerates a plant to produce higher levels of substance, which is harmless at low levels of a substance, however it becomes toxic when present in higher concentrations. .
Some new traits being made in genetic engineering have been to make plants such as soybeans to be herbicide resistant. Herbicides are used to kill weeds and other plants growing in the same area, but not the crop itself. Crops are inserted with a gene to make them resistant so they can withstand the chemicals in the herbicide, but the weeds cannot. This means that they can spray herbicides on the crops, but it will not kill them except for the weeds. Since, herbicide resistant traits are then transferred from crops to other plants by cross-pollination, and then weeds or other plants can get the genes and become resistant too. The UK Ministry of Agriculture, Fisheries and Food acknowledges that this has already happened.
