Claims that GM is quicker and more efficient than conventional breeding are as false as they are common.

It's often claimed that GM is much quicker than conventional breeding. But this isn't true, at least with plants that are bred through crossing (sexually propagated). Dr Doug Gurian-Sherman of the Union of Concerned Scientists explains below that the average time to develop a sexually propagated GM plant is 10-15 years - about the same as a comparable non-GM plant.

This is because laborious crossing and backcrossing breeding processes have to be carried out with the GM plant to try to eliminate some of the undesirable side-effects of the genetic engineering process and maximise the agronomic performance of the crop.

GMWatch speculates that this timeline might be reduced in the case of plants that are vegetatively propagated, like apples and potatoes, since the crossing and backcrossing carried out with sexually propagated plants does not happen.

Instead the genetic engineers insert the transgene and do some field testing to see that the transgenes function as hoped.

However, this shorter process may also carry greater risks.

Because there is no backcrossing or breeding of any kind, the GM apples or potatoes will always carry any and all changes that occurred during the engineering process, namely insertion-site mutations and effects and tissue culture-induced mutations and epigenetic changes. The GM varieties are put out into the field still carrying any GM-induced unintended changes.   

Other than checking that the apple trees and the potatoes look normal and grow OK during a couple of years of field testing under highly managed conditions, the developer company doesn't look for any other kinds of changes.

Here's Dr Doug Gurian-Sherman's comment about the time needed to develop GM versions of sexually propagated crops:

"The assertion that GM is quicker than breeding is common, but false. The average time required to develop a non-vegetatively engineered crop is about the same as developing one produced through breeding. This has been discussed in detail, for example, in 2000 and 2002 by Major Goodman, a highly respect corn breeder, geneticist, and member of the National Academy of Sciences in the US.

(Goodman M (2002) New sources of germplasm: Lines, transgenes, and breeders. In JM Martinez et al (eds.) (2002) Memoria Congresso Nacional de Fitogenetica, Univ. Autonimo Agr. Antonio Narro, Saltillo, Coah, Mexico: 28-41.

Goodman M & Carson M (2000) Reality vs. myth: Corn breeding, exotics, and genetic engineering. Proc. of the 55th Annual Corn & Sorghum Research Conference, Chicago, IL. 55:149–72.)

"The falsity stems from the notion that once a gene is found, it is simply a matter of sticking it into a plant and running a few tests to see if it works properly. In fact, years of field testing are needed to determine how well the trait responds in various and variable environments regardless of whether the trait is developed through GM or breeding.  

"Years of backcrossing are needed to get rid of possible harmful mutations and epigenetic changes introduced through the tissue culture process used with GM. And backcrossing is also needed to transfer the trait into multiple elite crop varieties of many crops (e.g. grains). Sometimes the original genetic construct turns out to cause problems (this happened for example with GE flood tolerant rice, that showed breeding to be faster and more effective than GM). New regulatory sequences are found to be needed, or there are position effects that cause problems from the particular site of insertion in the plant genome.

"When we look at actual examples, it has taken 10 to 15 years to develop a GM trait. And it is important to note that this is not an issue of delay due to regulatory requirements, as GM proponents are fond of asserting, but inherent in the limitations of the process."