Basics

Classes            Yields              Technical Control              Legislative Control

Classes                                                                     
Broadly speaking, today there are three different classes of genetically modified organisms (GMO), of which two are already commercialized.


GMO for herbicide tolerance
This class represents the largest trait in genetic engineering (GE). The plant is made resistant against a certain non-selective herbicide, either by adding or switching a certain gene. The plant’s resistance allows for the usage of this herbicide on the field. Two famous examples are RoundupReady® (active ingredient glyphosate) from Monsanto and LibertyLink® (active ingredient glufosinate) from Bayer.

GMO for insect resistance
In this second major class of GMO, genes are transferred to the plants to make them produce toxins against certain insects. These toxins mostly come from soil bacteria (e.g.  Bacillus thuringiensis) and are thus natural products which are already used in nature’s pest management. Today, these traits are especially common in maize and cotton. However, a downside is that the toxins also kill beneficial insects.

GMO for the production of chemicals
Although not commercialized, various companies try to develop plants through GE that can produce chemical substances for industry and medicine.


 

Yields                                                                                                            
When discussing the pros and cons of GMO, one major argument is that they can increase yields. However, it is important to distinguish between intrinsic and operational yields.

Intrinsic yields are the yields that can be achieved under ideal conditions.
Operational yields are obtained under field conditions, when environmental factors (pest, stress etc.) result in yields that are considerably less than ideal.
 “No currently available transgenic varieties enhance the intrinsic yield of any crops. The intrinsic yields of corn and soybeans did rise during the twentieth century, but not as a result of GE traits. Rather, they were due to successes in traditional breeding.” Union of Concerned Scientists (2009).
“Even the USDA admits that genetic engineering has not increased the yield potential of any commercialized GM crop.(Fernandez-Cornejo & Caswell, 2006).  

Technical Control
Although lobbyists claim that their methods only affect specific parts of the genetic code of an organism, they cannot fully control their impacts.
" plants transformed using current methods exhibit unintended genetic changes such as the insertion of superfluous DNA and various changes to the plant genomic DNA including base pair changes, small or large deletions, duplications, insertions, translocations and other DNA rearrangements.(Latham, Steinbrecher, Wilson; 2004).

Potential consequences:
A-Loss of gene function                         
B- Altered protien function.                   
C-Loss of gene expression.
 

Legislative Control     
Currently, most countries still lack an appropriate legislative framework and the experience to consider the long term health effects and environmental effects of increased pesticide usage, as well as the socio-economic effects on small-scale farmers. Criteria for the registration of GMO must be designed in a way that these aspects are also taken into account. A proposal for comprehensive risk assessment was published by Testbiotech in September 2010.