The gene is needed because it drives the production of gene messages from the genes inserted to provide herbicide tolerance, insect resistance, antibiotic resistance or a range of functions deemed to improve the commercial quality of the crop. In the absence of the promoter gene the inserted genes remain inactive, while in its presence the gene activity is maintained at a high level in all of the plant tissues, with little interference from changing environmental conditions that effect the activity of promoters native to the crop plant. The latter exchanges produce translocations and deletions in the chromosomes.
Recombination can produce unpredictable and potentially devastating gene arrangements.
For example, a growing body of evidence shows that plant DNA viruses may recombine to produce virus that attack animals or plant virus may be acquired from bacteria. It not yet clearly established as to the extent and frequency of such exchanges in contemporary time, however, it is clear that the specific virus diseases have only recently been described. J. Gen. Virol. Presently it is yet unclear when the virus jumped from plant to pig or whether or not the plant virus may continue to generate recombinants infecting animals. However, such 'authorities' fail to note that plant and animal pararetrovirus have a common origin and little effort has been made to find plant pararetrovirus DNA sequences of contemporary origin in animal pararetrovirus or in endogenous retrotransposon sequences.