Transgenics - GMO's: Genetically Modified Organisms: Molecular diagnosis (PCR).

The genetic modifications of plants intended to make a profit improving production or changing its characteristics. However, concerned about the impact that may have ultimately introducing other genetic material in some species, so there are regulations governing its use.

The selection of crops has been done since the beginning of agriculture selecionando plant seeds with specific characteristics. Subsequently, hybrids were obtained, and today with advances in recombinant DNA technology, genes which give the recipient plant certain features are introduced. Vegetables receiving new genes are generically called "genetically modified" (GMO: Genetically Modified Organisms), or transgenic.

The benefits sought are aimed at purposes like:

a) Increase quantity production, with consequent benefits for global food, improve crop quality, increasing their ability to synthesize vitamins, incorporate mineral or nutritional content elements such as beta-carotene, a precursor of vitamin a (p. eg. golden rice), or improve the quality making color change (p. eg. blue roses with genes obtained from petunias delfininas)

b) resistance to pesticides and herbicides as with glyphosate - resistant soybean, making production plants essential amino acids, blocking the synthesis of this product, or as with bromoxynil resistant cotton.

c) Resistance to pests caused by insects, introducing the Bt toxin gene, usually produced by the bacterium Bacillus thuringiensis (Bt). This bacterium has been used to biologically control certain pests, affecting the insects harmful to crops but does not affect beneficial as bees. This toxin does not affect vertebrates to be degraded by gastric acidity and not considered toxic to humans or animals.

d) resistance to some plant pathogens such as viruses in plants snuff, potatoes, tomatoes, peppers, zucchini, soybean, papaya, alfalfa, apricot, etc.

e) slow maturation of some fruits (p. eg. tomatoes) to facilitate preservation, and improve its texture, by introducing a gene which inhibits the formation of pectinase, an enzyme that activates aging the fruit and degrades the cell wall vegetables.

f) Resistance to environmental extremes, such as drought or cold, eliminating bacteria such as Erwinia herbicola and Pseudomonas syringae, which proteins act as nuclei of crystallization.

g) Incorporate the synthesis of specific proteins that can be used for human oral vaccination (edible vaccines).

However, it is noted that some of these elements could be hazardous to expose allergens and toxins, altering the environment, extending resistance to antibiotics, extend inserted to other plants by crossing or pollination genes, so there are detractors of this use, which is currently regulated, and for which consumers demand information about their use and food distribution.
Genes are introduced into plant cells in in vitro culture using biological vectors (plasmid Ti of Agrobacterium tumefaciens), physical methods such as electroporation or gun driving gene incorporated into microspheres colloidal gold (biolistic transformation), or chemical methods facilitators penetration of genes dealing with polyethylene glycol and calcium chloride. Of these, the most used is the biological vector, using the Ti plasmid of A. tumefaciens, containing the genes required for gene transfer and also the necessary elements for the inserted gene is expressed: promoter sequence, the gene inserted and the terminal sequence (terminator) to form what is called a "cassette" gene. The most commonly used promoter sequence is called cytopathogenic virus CaMV35S derived from "cauliflower mosaic virus" and the NOS terminator of the Ti plasmid of A. tumefaciens. For this reason, the CaMV35S promoter (abbreviated p35S), and the NOS terminator are usually investigated sequences when it is desired to know the presence of a transgene. It is also possible to investigate the presence of the inserted specific genes. Plants in which the use of transgenic has spread are maize and soybean, which turn their derivatives are incorporated in many foods. However, there are many other transgenic plants.
To detect plant organisms genetically or transgenic modified, can be investigated by a PCR test (Polymerase Chain Reaction) the presence of promoter, terminator, and / or inserted genes (transgenes) or detect the protein produced by the gene inserted by a method of enzyme immunoassay (ELISA). The primary advantage of molecular method (PCR) is that the result is not affected by the treatment that may have undergone food, but can not be performed in all laboratories. The advantage of ELISA is that method is more affordable to any laboratory, but the results may be affected by treatment has undergone food.