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Introduction One potential risk that is associated with commercial release of transgenic crops, most notably canola a nd c otton, i s t ransgene f low b etween c rops a nd t heir w ild r elatives ( Pilson & Prendeville 2004) . E llstrand et a l. (1999) reviewed t hat 12 out of t he w orld’s 13 m ost important c rops could h ybridize w ith wild r elatives, s uggesting t ransgene c ould escape vi a spontaneous hybridization with and introgression to wild relatives, even though this full list has n ot b een realized (Stewart et al. 2003). The escape o f transgenes into wild populations could e nhance t he w eediness or t he i nvasion of ne w h abitats, s ince t he t ransgenes pr ovide adaptive t raits s uch as resistance t o p ests, h erbicides, d iseases an d v arious en vironmental stresses ( Darmency 1 994). V olunteers a nd h ybrids w ere obs erved a groecosystems t ogether with sown crops and in their neighborhoods (Knispel et al. 2008; Warwick et al. 2008), and one of the causes was the occurrence of gene flow via pollen dispersal (Hall et al. 2000). Generally, gene flow can occur mainly via pollen and seed. Although more attention has been pa id t o t he pot ential of pol len di spersal, t he i ntentional m ovement of s eed dur ing harvesting, transportation and commerce may be of greater importance for the long-distance dispersal of t ransgenes. Seed l oss c an oc cur b ecause of t he pods s hattering be fore- and/or post-harvest op eration. The s maller t he s eed, t he greater t he r isk of gene flow i s t hrough dispersal m echanism b y w ind, a nimals or hum an a ctions. A ctually, m ost h ybrids b etween oilseed rape (OSR, Brassica napus) and wild relatives produce a plethora of small seeds (Eber et a l. 1994; C hadoeuf et a l. 1998; W ei & D armency 2008 ). S ome s tudies s howed t hat interspecific hybrids are present only among seeds with a diameter less than 1.6 mm (Eber et al. 1994; Baranger et al. 1995; Chèvre et al. 2000). For example, most crosses between OSR and wild relatives such as B. juncea (Bing et al. 1996), B. rapa (Jørgensen & Andersen 1994), Hirschfeldia i ncana and Raphanus r aphanistrum (Eber et a l. 1994; C hadoeuf et a l. 1998) only produced small seeds. Wei and Darmency (2008) found all hybrid seeds formed between a ma le s terile OSR c ultivar a nd f our w ild s pecies w ere s mall. It w as s uggested th at s mall seeds would result in a fitness disadvantage since seed mass would affect the emergence and initial seedling size (Aparicio et al. 2002; Westoby et al. 2002). Subsequent decrease of plant fitness of small-seeded plants might be exacerbated unde r stressful conditions such as hi gh density, shade, drought or herbivory (Gardner & Vanderlip 1989; Verdu & Traveset 2005). Thus, the hypothesis was proposed that gene flow might be hampered by small seed size of hybrids between transgenic crops and wild relatives (Wei & Darmency 2008). In that paper 37
plant growth was evaluated without taking into consideration the competition among plants of different s eed s izes. T he ef fect o f s eed s ize w as o nly o bserved i n t he f ield at e arly establishment under direct-sowing of seeds. Transgenic OSR and wild B. juncea and their hybrids were employed in this study to test d ifferent p erformance b etween s mall-seeded h ybrids an d l arger-seeded on es unde r competition with ea ch o ther. OSR i s an an nual crop s pecies, p referentially s elf-compatible, but outcrossing ranges from 12 to 47% (Becker et al. 1992). Both insect and wind-pollination occurs and pl ants have t he potential to establish outside cultivation (Timmons et al. 1995). Besides t he di spersal of a bundant pol len ( Lavigne et a l. 1998), pods s hattering be fore, or spilling during, ha rvest encourage s eeds t o e nter i nto t he s eed ba nk. S econdary dor mancy results i n t he pot ential s urvival i n s eed ba nks f or years (Gulden et a l. 2003). T hese s eeds potentially give rise to volunteers in the subsequent years that are either a source or a recipient of transgene introgression events, facilitating transgene escape (Pivard et al. 2008). B. juncea, an allotetraploid wild relative species, is frequently found as a weed and a ruderal component of r oadsides a nd w aste pl aces i n C hina. H ybrids a nd s ubsequent ba ckcross g enerations between B. napus and wild B. juncea were successfully obtained by open pollination (Frello et a l. 1995; B ing et a l. 1996; S ong et a l. 2007; L iu et a l. 2010). T he r elatively high compatibility between B. napus and wild B. juncea raises the biosafety concern of transgene introgression. In this study, we focus on components of plant fitness of different seed size categories in t he a gro-ecosystem and t heir i nteraction w ith t ransgene i ntrogression. T he w ork w as conducted in condition of plant competition at different plant densities. Materials and methods Plants Wild brown mustard (Brassica juncea var. gracilis, 2n = 36, AABB), transgenic oilseed rape (B. napus cv. W estar, 2 n = 38, AACC) a nd t he non-transgenic O SR pa rent ( Westar) w ere grown. S eeds of w ild br own m ustard or iginated f rom a l ocal f ield c ollection, pr ovided b y Nanjing Agricultural University, China. Brassica napus cv. ‘Westar’, a spring type OSR, was transformed w ith t he pS AM 12 pl asmid c ontaining genetically l inked G FP a nd B t C ry1Ac cassettes r egulated b y i ndependent C aMV 35S promoters ( Halfhill et a l. 2001). T he t hird generation of the progenies of transgenic event 1 (GT) was used in this study (Di et al. 2009). 38
Page 1 and 2: UNIVERSITE DE BOURGOGNE THÈSE Pour
Page 3 and 4: REMERCIEMENTS My heartfelt thanks g
Page 5 and 6: forming many of the ideas I present
Page 7 and 8: Abstract In the framework of commer
Page 9 and 10: 2.3 A rticle 2: Les r étrocroiseme
Page 11 and 12: Table 3.2. Parameters of linear reg
Page 13 and 14: experiment. BC1NS is separated into
Page 15 and 16: Fig. 4.7. Mean and standard error (
Page 17 and 18: INTRODUCTION GENERALE Dans le cadre
Page 19 and 20: chapitre 1 dressant l’état des c
Page 21 and 22: CHAPTER 1 LITERATURE REVIEW ON THE
Page 23 and 24: oilseed rape and B. oleracea is ver
Page 25 and 26: populations is reduced as the dista
Page 27 and 28: into hybrids would affect the morph
Page 29 and 30: Snow e t a l. ( 1999) f ound no f i
Page 31 and 32: 1.5 Consequences of introgression I
Page 33 and 34: more flowers and larger plant size
Page 35 and 36: Moreover, beside the introgression
Page 37 and 38: their parental plants. Moon et al.
Page 39 and 40: 2.1 Introduction CHAPTER 2 CONDITIO
Page 41: ARTICLE 1 The effect of seed size o
Page 45 and 46: These two experiments were kept wee
Page 47 and 48: interactions were found among the t
Page 49 and 50: 2006) or m ore f it t han their pa
Page 51 and 52: they b ear b eneficial t ransgenes
Page 53 and 54: Diggle PK, Abrahamson NJ, Baker RL
Page 55 and 56: Ramachandran S , B untin G D, A ll
Page 57 and 58: Table 2.2. F -values f rom a f ive-
Page 59 and 60: Days to flowering Biomass Per. of s
Page 61 and 62: 2.3 Article 2: Les rétrocroisement
Page 63 and 64: Photo.2.3. S praying chlorsulfuron
Page 65 and 66: Introduction In t he f ramework o f
Page 67 and 68: eceived p ollens f rom wild B. j un
Page 69 and 70: Statistical analysis Mean values ar
Page 71 and 72: Characteristics of the backcrosses
Page 73 and 74: Table 2.7. Mean (±95% CL) of plant
Page 75 and 76: plants w ith B. napus morphology t
Page 77 and 78: Productivity of the resistant proge
Page 79 and 80: References [1] A .A. Snow, D .A. A
Page 81 and 82: insight into adaptive life-history
Page 83 and 84: CHAPTER 3 EFFETS DE LA RESISTANCE A
Page 85 and 86: 3.2 A rticle 3 : S imulation d e l
Page 87 and 88: compétition et le devenir des popu
Page 89 and 90: difficult to predict. Similarly, it
Page 91 and 92: Table 3.1: ANOVA results of the eff
Page 93 and 94:
Table 3.2: Parameters of linear reg
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herbivores than when exposed to Bt
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esistant hybrid populations might i
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Letourneau D .K., H agen J .A., 200
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Germination rate 0.6 0.5 0.4 0.3 0.
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3.3 Article 4: Compétition entre p
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Introduction The invasion of transg
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Whether a popul ation w ill e volve
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while ensuring that the same ratio
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silique number, seed number, seed w
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Our ga rden e xperiments s howed t
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experiment, harsh growth conditions
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References Agrawal AA. 2004. R esis
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density- dependent c osts of vi ral
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Table 3.5. F values of the analysis
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Table 3.7. Results of Helmert contr
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Fig. 3.4. Examples of experimental
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Flowering date Seed weight Biomass
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No. viable seeds Biomass 50000 4000
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Photo 3.3. Cotton bollworm (Helicov
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Introduction Spontaneous introgress
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screening as transgenic BC2 (trBC2)
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2002), but certain studies showed n
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Acknowledgements We t hank Z hixi T
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92, 368-374. Rieseberg, LH, and Bur
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Table 3.10. F-values of three-way A
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Seed number Biomass 140 120 100 80
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CHAPTER 4 RECHERCHE DES CONSEQUENCE
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Photo 4.1. Wild radish in a herbici
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Introduction Plant divergence is ge
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or t he popul ation of wild r adish
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estimated. All the seeds of every h
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Field experiment Number of siliques
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aphanistrum from hybrids and R. sat
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competition diminished the differen
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Conner, J. K., Rice A. M., Stewart
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Rattenbury J A. 1962. C yclic h ybr
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Fig. 4.1. Four r egions where w ild
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Fig. 4.3. Flower phot os showing pe
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Fig. 4.5. Plot of the first two axe
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Plant weight No. of seeds per plant
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Emergence rate Plant weight No.of a
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CONCLUSION 172
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véritable s uccès ad aptatif d an
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Dans l e cas d es p remières gén
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REFERENCES Abbott RJ, Comes HP.2007
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Bing D J, D owney R K and R akow G
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carinata and Brassica rapa. Plant B
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Hybridisation within Brassica and a
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etween weedy Brassica rapa and oils
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Hybridization between oilseed rape
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Nosil P. 2008. Speciation with gene
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32:305-32 Schadler, M., R. Brandl,
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Thalmann C, Guadagnuolo R, Felber F
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Zheng XM and Ge S. 2010. Ecological
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Therefore, after a review of the st
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more easily sieved out by harvester
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Transgenic F1 produced higher bioma
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