UNIVERSITE DE BOURGOGNE THÈSE Yongbo LIU - Université de ...

Snow e t a l. ( 1999) f ound no f itness c ost a ssociated w ith t he e xpression of a
glyphosinate-resistance t ransgene a fter i ntrogressing t he t ransgene from oilseed r ape t o B.
rapa. M oreover, Ammitzboll e t a l. ( 2005) f ound no di fference i n g lyphosate transgene
expression at mRNA level in hybrids compared to their transgenic oilseed rape parents, which
indicates this particular transgene expression was not impacted by genotypic background. Of
course, t his m ight not be t he c ase f or ot her t ransgenes. A fter h ybridization of he rbicideresistant
Brassica napus (oilseed rape) and Raphanus raphanistrum (wild radish), 18% of the
progeny obtained from resistant hybrids were resistant in each advanced generation (G8-G11)
in t he pr esence of he rbicide s election pr essure ( Al M ouemar a nd D armency 2004) , w hich
suggests t he i ntrogression of t ransgene i n w ild radish popul ations i s un stable. F ord e t a l.
(2006) have identified one triploid F1 hybrid, nine diploid and two near triploid introgressants
with flow cytometry and crop-specific microsatellite markers in B. oleracea wild populations
where B. napus and B. oleracea grew together, which suggests newly discovered capacity for
spontaneous introgression into B. oleracea.
These results suggest that these transgenes could be introgressed in wild populations.
For example, i n C anada, one i ntrogressed i ndividual of Brassica ra pa was d etected as
displaying r esistance to glyphosate six years after the last GM oilseed rape (B. napus) was
grown on the field even in absence of the glyphosate selection pressure (Warwick et al. 2008).
In United States, Whitton et al. (1997) and Linder et al. (1998) found that introgression o f
cultivar l oci w as w idespread i n w ild s unflower ( Helianthus annuus ) popul ations, a nd t he
sympatric wild populations have been replaced by advanced generation hybrids. Snow et al.
(2010) found that crop-specific alleles persisted 10 years in four weedy populations of hybrids
between wild radish (Raphanus raphanistrum) and R. sativus, suggesting that neutral or even
detrimental genes can persist rather frequently in the wild (Table 1.4).
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