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

oth s howed f itness cost [ 25], but t here a re many ALS m utations e ndowing h erbicide-
resistance s o t hat ge neralizations c ould not be made. In our e xperiment, t he r esistant B C1
(BC1NR) ha d hi gher frequency of B. napus morphology a nd l arger f lower s ize t han
susceptible B C1 (BC1NS). P lants w ith B. napu s morphology a re m ore r obust, which c ould
help BC1NR plants to establish in a mixed stand. Similarly, larger flowers like oilseed rape
flowers c ould attract mo re f oraging in sects, w hich is a gain a w ay to b etter d isperse th e B.
napus characteristics – and t he h erbicide-resistance – in r uderal a nd r oadside pl ant
communities. As for the higher performances of BC1NS* compared to BC1NS, we suppose
that the largest plants producing the highest number of flowers were more frequently visited
by t he h ouseflies c arrying f oreign pol len, w hich c ould r esult i n t he pr oduction of r esistant
seeds, i n c ontrast t o t he s mallest pl ants. T his ph enomenon c ould m ake t he di spersal of t he
resistance gene more rapid again.
Finally, the presence of herbicide-resistant plants in the progeny of susceptible F2, BC1N
and conventional B. napus indicated that the first generation progeny of the hybrid is capable
of tr ansmitting th e h erbicide-resistance gene t o B. napus volunteers and f eral popul ations,
which provides an unexpected way to the transfer of transgenes via pollen dispersal from GM
crops to non-GM crops [26]. It is also a source for further gene flow and introgression [8].
Our results show that the B. napus-like BC1 plants produced with B. napus pollen are v ery
likely to establish and persist in the fields and along roadsides as false feral crop population.
They look l ike B. napus volunteers but di splay additional ge netic va riability t hat a llow f or
further adaptation of the plants and propagate the herbicide-resistance gene. In particular, they
could have inherited from the wild B. juncea long-term seed viability in the soil, which can
make them even weedier [2]. This phenomenon should be considered in biosafety assessment
of genetically modified oilseed rape with herbicide-resistance traits.
Acknowledgements
The authors thank Alain FLEURY and Zhixi TANG for their assistance in the experiments.
This work was supported by a PhD joint fellowship between France (CNOUS, No. 20072315)
and China (Natural Science Foundation, grant No. 30970432).
73