Competitiveness of transgenic oilseed rape

Abstract

The competitiveness of two transgenic oilseed rape (Brassica napus ssp. napus) lines and their fertile transgenic hybrid was tested in field trials in Belgium and Denmark. The lines contained genes for male sterility, restoration of fertility and herbicide resistance. The competitiveness of the three transgenic lines was related to three non-transformed commercially-grown oilseed rape varieties: Drakkar, Topas and Line. As a reference of a more aggressive crucifer, white mustard (Sinapis alba) was also included in the experiment. The experimental design was a complete block design with two locations, monocultures and mixtures with barley (Hordeum vulgate), three plant densities, four harvest times and four blocks. The yield density relationship of the transgenic oilseed rape lines was not different from that of the non-transgenic varieties in either location. The first harvest times showed a vigorous biomass production of white mustard, which in turn produced a significant difference in the competitive ability between oilseed rape and white mustard. Later, this difference decreased, and in Belgium there was no difference at the last harvest time. Variations within populations may blur actual differences between lines and varieties, and it is argued that unless the experimental design covers a range of competitiveness for which it is possible to detect significant differences, test results reporting a lack of difference between transgenic and non-transgenic plants are of little value.

Management of herbicide-tolerant oilseed rape in Europe: a case study on minimizing vertical gene flow

“…Moreover, several field studies report that the presence of a HT trait in oilseed rape does not confer a competitive advantage, unless the herbicide is applied. In the absence of the relevant herbicide, HT plants are not more invasive or persistent than untransformed control plants (Beckie et al, 2001;Crawley et al, 1993Crawley et al, , 2001Downey, 1999;Fredshavn et al, 1995;Norris and Sweet, 2002;Norris et al, 1999;Simpson et al, 1999;Warwick et al, 1999Warwick et al, , 2004Wilkinson et al, 1995). The numbers of HT volunteers in the years following the cultivation of transgenic HT oilseed rape appear to be comparable to, or less than the amount of volunteers in conventional oilseed rape Crawley et al, 1993;Gulden, 2003;Hails et al, 1997;Norris and Sweet, 2002;Norris et al, 1999;Roller et al, 2003;Simard et al, 2002;Sweet et al, 1997;Wilkinson et al, 1995).…”

Scientific Opinion on application (EFSA‐GMO‐NL‐2010‐87) for the placing on the market of genetically modified herbicide tolerant oilseed rape GT73 for food containing or consisting of, and food produced from or containing ingredients produced from, oilseed rape GT73 (with the exception of refined oil and food additives) under Regulation (EC) No 1829/2003 from Monsanto

“…These experiments demonstrated that the genetic modification per se does not enhance ecological fitness. Ecophysiological experiments on comparative fitness between the GM plant and its non-GM counterpart and modelling did not indicate that genes conferring herbicide tolerance significantly alter the competitive ability of GM plants (Fredshavn et al, 1995;Warwick et al, 1999Warwick et al, , 2009Norris and Sweet, 2002;Claessen et al, 2005a,b;Simard et al, 2005;Londo et al, 2010). Beckie et al (2004) showed that GMHT oilseed rape with single or multiple herbicide tolerance traits is not more persistent (weedier) than non-GMHT plants.…”

Herbicide‐tolerant crops in agriculture: oilseed rape as a case study

“…However, this did not translate into increased competitiveness or`weediness' of OSR under the conditions of their study (Stewart et al 1997). Other studies have shown that transgenic sugar beet and OSR did not dier in their competitiveness compared with non-transgenic controls (Fredshavn et al 1995, Fredshavn andPoulsen 1996). Work by Norris et al (1999) indicated that weediness and invasiveness of herbicide-tolerant and high laurate OSR was not enhanced by the presence of the transgenes, con®rming previous reports (Booth et al 1996, Sweet et al 1997, Crawley et al 1993).…”