Below are listed some  examples  of  GM crop problems that in all likelihood are caused by an underlying disruption of host gene function due to the GM transformation process (the act of inserting foreign genes into plants). It is important to note that these problems reflect disturbances in many (perhaps tens or even hundreds) of gene functions. These studies and real farming experiences highlight very clearly how the GM transformation process involving a single GM gene insertion event can have general, major negative physiological consequences in terms of crop performance.  

GM Crop Performance Problems:

Cotton ball and tap root developmental abnormalities.

(Allen R. Myerson, ‘Seeds of Discontent: Cotton Growers Say Strain Cuts Yields’, in New York Times November 19, 1997)

An increase (50-fold) in carotene (Vit A) in rapeseed oil was achieved by introducing and overexpressing the bacterial phytoene synthase (crtB) gene in a seed-specific manner in GM oilseed rape. However, in addition there was (i) a significant decrease in tocopherol (Vit E), (ii) fatty acid composition was significantly altered and (iii) chlorophyll levels were reduced in developing seed.

(C.K. Shewmaker and others, ‘Seed-specific overexpression of phytoene synthase: increase in carotenoids and other metabolic effects’, in Plant Journal 20 (1999),  pp. 401-412.) 

Side-by-side field trials over a 2-year period at 4 different locations of compared GM and equivalent non-GM varieties of glyphosate-resistant (GR) soybean cultivars. The authors’ of this study conclude: “Yields were suppressed  with GR soybean cultivars .... The work reported here demonstrates that a 5% yield suppression was related to the gene or its insertion process and another 5% suppression was due to cultivar genetic differential.”

(R.W. Elmore and others, ‘Glyphosate-Resistant Soybean Cultivar Yields Compared with Sister Lines’, in Agronomy Journal 93 (2001), pp. 408-412.)

GM cotton (variety Paymaster 1560 BG) engineered to contain the Bt toxin aimed at conferring resistance to the budworm pest, unexpectedly showed a dramatic increase in root-knot nematode susceptibility compared with its non-GM parent. (The root-knot nematode is a widespread and serious pest of cotton.)

(P.D. Colyer, T.L. Kirkpatrick, W. D. Caldwell and P.R. Vernon, ‘Root-Knot Nematode Reproduction and Root Galling Severity on Related Conventional and Transgenic Cotton Cultivars’, in The Journal of Cotton Science 4 (2000), pp. 232-236.)

High lignin content in GM Soya resulting in stem splitting under high ambient temperatures.

Poor expression of the EPSPS transgene in a certain variety of GM Soya resulting in low tolerance to glyphosate and resultant crop losses.

(See ‘Yellowing of soybean leaves may be result of several factors’, in Forrest Rose 22^nd August 2001; can be found on
 http://agebb.missouri.edu/news/queries/showcur.idc?story_num=1298&iln=390 ).)

GM food:  Potential health problems

Disruption of host gene function may produce an increase in known toxins or the generation of new toxins.

Rats fed on GM potatoes containing a snowdrop insecticide (GNA) producing gene suffered a weakened immune system, impairment to the development of the internal organs and gut lesions.

(S.W.B. Ewen og A. Pusztai,  ‘Effects of diets containing genetically modified potatoes expressing Galanthus nivalis lectin on rat small intestine’, in The Lancet 354 (1999), pp. 1353-1354.)

Mice fed GM potatoes containing the bacterial Bt toxin gene developed intestinal lesions.

(N.H. Fares og A.K. El-Sayed, ‘Fine structural changes in the ileum of mice fed on endotoxin-treated potatoes and transgenic potatoes’, in Natural Toxins 6 (1998), pp. 219-233.)

A combination of novel toxin production and inadequate purification in the manufacture of the natural amino acid dietary supplement L-tryptophan from GM bacteria and taken as a sleeping aid and antidepressant, seems to be the cause of a novel disease-eosinophilia-myalgia syndrome - EMS (USA, July - December 1989). [ The total epidemic cases have been estimated at 5,000 - 10,000. ~1500 permanent disabilities; 38 deaths to date].

(See: A.N. Mayeno, F. Lin, C.S. Foote, D.A. Loegering, M.M. Ames, C.W. Hedberg og G.J. Gleich,  ‘Characterization of “peak E” a novel amino acid associated with eosinophilia-myalgia syndrome’, in Science 250 (1990), pp. 1707-1708. See also: T.J. Simat, K.K. Kleeberg, B. Muller og A. Sierts, ‘Synthesis, formation, and occurrence of contaminants in biotechnologically manufactured L-tryptophan’, in Advanced Experimental Medical Biology 467 (1999), pp. 469-480.)