Genetically modified (GM) crops are faced with the potential problem of ‘passing’ DNA to unwanted species such as weeds which could lead to the formation of ‘super weeds’. Fortunately the risk of this happening is low. Nevertheless, new genetic techniques such as transgenic mitigation are now being used to make GM crops safer than ever before so that our beautiful planet remains the way it is.
GM crops are created by inserting DNA from one organism into a crop, in order to give it a useful advantage, known as the transgene. Nearly 90% of corn in the USA has been GM with a transgene that gives resistance to a herbicide called glyphosate. This allows the herbicide to be used without affecting the crop, so you get more food.
Although GM crops are widely used and have numerous advantages, there is growing fear that they may ‘give’ their DNA to wild relatives due to pollination. Many also worry that GM crop’s transgenes may be passed to weeds, making them resistant to herbicides forming ‘super weeds’. Still, there is no need to be alarmed since the risk of this happening is low. However the fact that there is a probability that this can happen has led to the implementation of new strategies to reduce the risk even further.
Transgenic mitigation is an innovative genetic technique that is useful at controlling transgenes that escape into unwanted plants, especially weeds. This helps prevent the formation of ‘super weeds’. Genetic engineering is used to link the transgene to another gene known as the mitigator gene in the GM crop. The mitigator gene is like an automatic security switch that will react differently depending on which crop it is found. If we use GM corn as an example, the mitigator gene may be beneficial or neutral to the growth or reproduction of the corn. However in the unlikely case the transgene passes into a weedy population, the mitigator gene will have an unfavorable effect on the weed, making it is less likely to compete with the normal weeds. The deleterious effects include: reduced seed dormancy, dwarfing and loss of shattering.
Transgenic mitigation can therefore be very useful, not only in preventing the formation of ‘super weeds’ but also to prevent the transmission of pest and pathogen resistances that are used in some GM crops. People that oppose GM crops on the basis that their DNA can ‘pollute’ other plants may be more open on the matter.
Figure 1. 1) NTM (non transgenic mitigated) corn that is GM may pass its genes to wild weed forming ‘super weeds’ that are herbicide resistant. 2) TM (transgenic mitigated) corn may pass its genes to wild weed but the produced weeds will be much weaker than the ‘normal’ weed. http://www.fenceinstallationnorthlondon.co.uk/blog/102-difference-between-weeds-and-plants-greenfellas http://www.parksbrothers.com/is-our-sweet-corn-gmo/
Although transgenic mitigation prevents transgenes settling in weed populations for long periods of times, it may fail in extreme cases. Nature is nature and nothing is impossible e.g. an spontaneous mutation may occur. This is a random change in the DNA inside the cell which can result in the switching off of the mitigation gene. If this were to happen the mitigation gene wouldn’t cause a detrimental effect on the weed so it would be able to survive and out-compete the normal weed.