Search results for "flux de gene"
showing 10 items of 24 documents
Fitness of backcross six of hybrids between transgenic oilseed rape (Brassica napus) and wild radish (Raphanus raphanistrum
2002
The process of introgression between a transgenic crop modified for better agronomic characters and a wild relative could lead potentially to increased weediness and adaptation to the environment of the wild species. However, the formation of hybrid and hybrid progeny could be associated with functional imbalance and low fitness, which reduces the risk of gene escape and establishment of the wild species in the field. Our work compares the fitness components of parents and different types of backcross in the sixth generation of hybrids between transgenic oilseed rape (Brassica napus, AACC, 2n = 38) resistant to the herbicide glufosinate and wild radish (Raphanus raphanistrum, RrRr, 2n = 18)…
Introduction of genotypic effects into Genesys-Rape : the example of height and male sterility
2005
Abstract The aim of this study was to introduce effects of rape genotypes on gene flow between rape populations into the existing GeneSys - Rape model and to simulate the influence of existing rapeseed cultivars on gene flow between rapeseed populations in time and in space. The GeneSys - Rape input variables are the regional field pattern, crop successions, cultivation techniques and genotype of cropped cultivars. The main output variables are, for each year and plot, the number of individuals per square meter and the genotype proportions in the harvest. Results comprised: (1) sensitivity analyses of the model to cultivar characteristics, which showed the importance of pollen emission on g…
Using the GENESYS model quantifying the effect of cropping systems on gene escape from GM rape varieties to evaluate and design cropping systems.
2004
Gene flow in rapeseed is a process taking place both in space and over the years and cannot be studied exclusively by field trials. Consequently, the GENESYS model was developed to quantify the effects of cropping systems on transgene escape from rapeseed crops to rapeseed volunteers in neighbour plots and in the subsequent crops. In the present work, this model was used to evaluate the risk of rape harvest contamination by extraneous genes in various farming systems in case of co-existing GM, conventional and organic crops. When 50 % of the rape varieties in the region were transgenic, the rate of GM seeds in non-GM crop harvests on farms with large fields was lower than the 0.9 % purity t…
GenExP, un logiciel simulateur de paysages agricoles pour l'étude de la diffusion de transgènes
2007
; The software GENEXP allows to simulate 2-dimensional agricultural landscapes by using a traditional algorithmic geometry. Based on real or realistic field-patterns, GENEXP provides multiannual maps of agricultural landscapes, which are used by softwares simulating the dispersal of GM pollen grains and seeds at various scales.; GENEXP est un simulateur de paysages agricoles qui engendre des découpages parcellaires en utilisant une géométrie algorithmique classique. GENEXP fournit, sur la base de parcellaires réels ou réalistes, des cartes pluriannuelles de paysages agricoles utilisables par des logiciels qui simulent la dispersion des pollens et des graines d'OGM à différentes échelles.
Polymorphism for interspecific hybridisation within a population of wild radish (Raphanus raphanistrum) pollinated by oilseed rape (Brassica napus)
2001
The within-population polymorphism of wild radish (Raphanus raphanistrum) for interspecific hybridisation with two cultivars of oilseed rape (Brassica napus) was investigated by hand crossing experiments and fluorescence microscopy. Wide variability among plants was observed in the ability of oilseed rape pollen to germinate on the wild radish stigma; the frequency of pistils showing pollen tubes ranged from 0 to 1, depending on the female plant. The ratio of fertilised ovules to the total number of ovules in ovaries where pollen tubes arrived ranged from 0.02 to 0.51. Overall, the results provide evidence for the presence of different phenotypes. In 40% of the plants, pistils had no or ver…
Effect of a gap on gene flow between otherwise adjacent transgenic Brassica napus crops.
2003
Gene flow resulting from cross pollination becomes an issue when transgenic crops are involved and the genetic modification carries a trait of ecological importance. As crop fields are often separated by a barren gap, such as an intervening roadway or unplanted area, I measured cross contamination between two herbicide-resistant transgenic fields (canola, Brassica napus) across a gap of up to 12 m. I focused on pollen exchange from the field border up to 7 m inside each field over two seasons. In the absence of a gap, I found that gene dispersal diminished rapidly with distance, with more than 40% of transgenic progeny found within the first meter from the edge of the adjacent crop. Cross c…
Neutral modelling of agricultural landscapes by tessellation methods: the GenExP-LandSiTes software - Application to the simulation of gene flow
2010
International audience; We present a three steps approach that aimed at simulating neutral agricultural landscape models: (1) we characterized the geometry of three real field patterns; (2) we generated simulated field patterns with two tessellation methods attempting to control the value of some of the observed characteristics and, (3) we evaluated the simulated field patterns. The first two steps were integrated to the GenExP-LandSiTes software that thus simulates two-dimensional agricultural landscapes. It is written in Java, and it is freely accessible through a Gnu Public Licence. For the third step, we considered that good simulated field patterns should capture characteristics of rea…
Last results concerning gene flow from transgenic oilseed rape to wild radish
1999
International audience
Using the GeneSys model quantifying the effect of cropping systems on gene flow from GM rape varieties to rape volunteers for evaluating and designin…
2004
International audience
Using the GeneSys model quantifying the effect of cropping systems on gene flow from GM rape varieties to rape volunteers to evaluate and design crop…
2004
National audience