A comparison between crop domestication, classical plant breeding, and genetic engineering

Several claims have been made about genetic engineering (GE) in comparison with crop domestication and classical plant breeding, including the similarity of genetic changes between those taking place during domestication and by GE, the increased speed and accuracy of GE over classical plant breeding, and the higher level of knowledge about the actual genes being transferred by GE compared with classical breeding. In reviewing evidence pertaining to these claims, I suggest that (i) it is unlikely that changes introduced by GE will make crops weedier, although exceptions have been noted, (ii) changes brought about by GE currently often involve gain-of-function mutations, whereas changes selected during domestication generally involve loss-of-function mutations, (iii) adoption of GE cultivars has been much faster than any previous introduction and spread of agriculture that occurred earlier but has occurred at about the same rate as the spread of cultivars obtained by plant breeding, (iv) introduction of agriculture reduced the health of agriculturists compared with that of hunter-gatherers, suggesting that introduction of innovations do not automatically improve well being, (v) although GE is not a substitute for plant breeding, it can significantly contribute to plant breeding by generating additional genetic diversity, (vi) uncertainties associated with the site of insertion of transgenes in the genome and the expression of transgenes following insertion, makes GE less rapid and precise than originally claimed, and (vii) a potential advantage of GE over classical breeding is the knowledge of the actual gene(s) being inserted, although few cases of unwanted gene introductions through classical plant breeding have been documented. Further advances in GE will increase the precision of the technique, its relevance to consumers, and its environmental friendliness. What is most needed are evenhanded, case-by-case assessments of the benefits and potential pitfalls of GE in comparison with other crop improvement techniques. Classical plant breeding may, in the end, also be regulated in the same way as GE.