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

CHAPTER 1
LITERATURE REVIEW ON THE CONSEQUENCES OF
GENE FLOW FROM OILSEED RAPE TO ITS RELATIVES
Gene flow and introgression between transgenic crops and wild relatives is considered one of
undesirable co nsequences o f co mmercial r elease o f genetically mo dified ( GM) / t ransgenic
crops c onferring h erbicide, i nsect or vi rus-resistance genes. C ommercialized G M cr ops
involving m any i mportant r esources s pecies, s uch a s s oybean, m aize, c otton, oi lseed r ape,
squash, papaya, alfalfa and sugarbeet, are cultivated worldwide (James 2009). Most of these
transgenic species could hybridize with their wild relatives (Ellstrand et al. 1999; Armstrong
et al. 2005).
Hybridization is a p rerequisite f or gene flow, and ge ne f low i s a p rerequisite f or
introgression. B ut, not all h ybridization c ould i nduce gene flow. Hybrids can form w hen
certain conditions are achieved, including sympatry with a compatible relative (weedy, wild
or crop), overlapping flowering phenology, pollen and seed dispersal, successful fertilization
and viable offspring. Successful gene flow does not necessarily result in gene introgression.
The introgression of transgenes into the receiving species or population depends mainly on
the barriers to hybridization and introgression, the evolution and fate of inter-specific hybrids,
their fitness, and the potential costs and benefits of transgenes in the offspring under variable
habitat conditions.
Inter-specific gene f low v ia h ybridization a nd s ubsequent i ntrogression pl ays a
biologically imp ortant r ole in th e a cquisition o f g enetic a daptations th rough n atural p lant
populations. It has been recognized that introgression can occur frequently and may produce
viable, e ven hi ghly-adapted, pr ogeny ( e.g., A rnold 1997, 2006; R ieseberg e t a l. 1999) ,
although e volutionary s cientists e arly f ocused on t he i mportant r ole of r are e vents of
introgression f or t he evolution of m any pl ant groups (e.g., Lotsy 191 6; A nderson 1949;
Stebbins 1959; Grant 1981).
We present here a literature survey on the processes and consequences of gene flow
and introgression between oilseed rape and its wild relatives. Such a topic has been ignored
before the release of GM varieties, but many studies have documented this issue to date.
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