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

Annex 1
GENERAL INTRODUCTION (English version)
The new traits would affect the growth and reproduction of interspecific hybride
progenies (Ellstrand et al. 1999; Snow et al. 2003; Halfhill et al. 2005; Campbell et al. 2006).
When resistant plants invade susceptible wild populations, or when the transgene conferring
resistance is transmitted to wild populations, the competition existing between resistant and
susceptible plants would impact both the two plant types, resistant and susceptible plants.
Because of the resistance advantage of the resistant plants, they might suppress the growth
of the susceptible plants for competing resources. At the same time, the competitive
interaction between resistant and susceptible plants is expected to vary as the relative
proportion of both plant types vary in the population because of the change of neighbors. In
addition, it is likely that this competitive interaction depends on the surrounding growth
conditions, such as resource availability, herbivory, herbicide and virus diseases pressures
(Ramachandran et al. 2000; Vacher et al. 2004; Campbell and Snow 2007).
Over the long term, the persistence of transgenes or transgenic plants in a wild
population should result in shift in the population dynamics, and affect the direction and
consequences of population variation. While transgenic plants dominate the wild population,
the susceptible wild plants may either coexist with resistant plants or face an endanger
situation, which could depend on the competition for resources and harsh conditions like
high herbivory (Stewart et al. 1997; Ramachandran et al. 2000; Letourneau and Hagen 2009).
Another important outcome could be the evolution of plant morphological (such as flower
color or size, fruit shape or seed size) and life-history traits (such as flowering time, growth
and reproduction, seed germination), because the transgene could be either directly related
with these traits or affect them indirectly via the long-term evolution process. However, the
study of long-term evolution processes is very difficult because of the lack of appropriate
(wild) transgenic materials and the limitation of time. An alternate method is using models
to carry out simulations, but models also need precise data to run. The discovery of a wild
population introgressed by conventional crops could be invaluable as an alternative for
detecting the possible long-term effects of gene flow and introgression between transgenic
crops and wild relatives.
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