Present address: SemBiosys Genetics Inc., 2985 23rd Ave NE, Calgory, Alberta, Canada T1Y 7L3
Mitigation of establishment of Brassica napus transgenes in volunteers using a tandem construct containing a selectively unfit gene
Article first published online: 16 AUG 2005
Plant Biotechnology Journal
Volume 4, Issue 1, pages 7–21, January 2006
How to Cite
Al-Ahmad, H., Dwyer, J., Moloney, M. and Gressel, J. (2006), Mitigation of establishment of Brassica napus transgenes in volunteers using a tandem construct containing a selectively unfit gene. Plant Biotechnology Journal, 4: 7–21. doi: 10.1111/j.1467-7652.2005.00152.x
- Issue published online: 16 AUG 2005
- Article first published online: 16 AUG 2005
- Received 30 March 2005; revised 9 June 2005; accepted 18 June 2005.
- Brassica napus;
- ecological competition;
- transgenic mitigation;
Transgenic oilseed rape (Brassica napus) plants may remain as ‘volunteer’ weeds in following crops, complicating cultivation and contaminating crop yield. Volunteers can become feral as well as act as a genetic bridge for the transfer of transgenes to weedy relatives. Transgenic mitigation using genes that are positive or neutral to the crop, but deleterious to weeds, should prevent volunteer establishment, as previously intimated using a tobacco (Nicotiana tabacum) model. A transgenically mitigated (TM), dwarf, herbicide-resistant construct using a gibberellic acid-insensitive (Δgai) gene in the B. napus crop was effective in offsetting the risks of transgene establishment in volunteer populations of B. napus. This may be useful in the absence of herbicide, e.g. when wheat is rotated with oilseed rape. The TM dwarf B. napus plants grown alone had a much higher yield than the non-transgenics, but were exceedingly unfit in competition with non-transgenic tall cohorts. The reproductive fitness of TM B. napus was 0% at 2.5-cm and 4% at 5-cm spacing between glasshouse-grown plants relative to non-transgenic B. napus. Under screen-house conditions, the reproductive fitness of TM B. napus relative to non-transgenic B. napus was less than 12%, and the harvest index of the TM plants was less than 40% of that of the non-transgenic competitors. The data clearly indicate that the Δgai gene greatly enhances the yield in a weed-free transgenic crop, but the dwarf plants can be eliminated when competing with non-transgenic cohorts (and presumably other species) when the selective herbicide is not used.