Backcrosses to Brassica napus of hybrids between B. juncea and B. napus as a source of herbicide-resistant volunteer-like feral populations
2010
Liu, Y.B. | Wei, W. | Ma, K.P. | Darmency, H.
Introgression between genetically modified (GM) crops and wild relatives is considered to potentially modify the genetic background of the wild species. The emergence of volunteer-like feral populations through backcross of hybrids to the crop is also a concern. The progeny of spontaneous hybrids between mutant herbicide-resistant oilseed rape (Brassica napus) and wild B. juncea was obtained. Parents, F₂ and BC₁ to B. napus were planted together in the field so as to study their performance. The chromosome number of BC₁ followed a Normal distribution. Mendelian ratio of the herbicide-resistance gene was found. The F₂ produced less seeds than B. napus, and BC₁ had intermediate production. Herbicide-resistant BC₁ were not different of their susceptible counterparts for plant weight, seed weight and seed number, but most of them exhibited B. napus morphology and larger flowers than the susceptible BC₁. They displayed an important genetic variability allowing further adaptation and propagation of the herbicide-resistance gene. Pollen flow to susceptible plants within the mixed stand was observed. As a consequence, the resistant BC₁ produced with B. napus pollen could frequently occur and easily establish as a false feral crop population within fields and along roadsides.
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