A Study On Ecological Adaptability For The Potential Invasiveness Of Bt-transgenic Brassica Napus L

With the global cultivation area of genetically modified crops increased, the ecological risk assessment of genetically modified crops received concerns, especially the potential invasiveness of transgenic crops. Most of transgenic crops are often cross-pollination crops, so that the occurrence of gene flow from crops to their wild relatives is common. This makes transgenes escape to wild relatives, which could lead to the risk of invasion of transgenic crops into wild populations if the heritance of transgenes are stable in progenies and transgenic plants have competitive advantages.Here, we employed Bt-transgenic oilseed rape(Brassica napus L.), a model species to study gene flow of transgenic crops, and its wild relative species, brown mustard (B juncea). First, the hybridization and backcross was detected between B. napus and B.juncea; Second, we tested the heritance and expression of Bt gene in the offspring; Third, in greenhouse, we designed different plant densities to evaluate the fitness performance and competition correlation between oilseed rape and mustard under different competition conditions. Finally, we simulated an invasion process of transgenic oilseed rape into wild mustard populations and detected their performance and the variation of population production. Results showed that:1. Bt-ransgenic B. napus successfully hybridized with B. juncea, and obtained fertile hybrid and backcross progeny.2. Bt gene can be inherited in hybrids and backcrosses, and Mendelian ratio of the Bt gene was found.3. There no fitness cost of Bt gene was found in the absence of insects. Competition had significant effects on plant vegetative growth and reproductive growth.4.Bt-transgenic B. napus were not superior competitors compared to B. juncea in the absence of insects or in the presence of insects. In the presence of insects, since Bt-transgenic B. napus decreased the abundance of insects in the ecosystems, it could protect B. juncea against insects. With the increase of Bt-transgenic B. napus, seed weight of B. juncea increased linearly.In conclusion, although the successful hybridization between.Bt-transgenic B. napus and B. juncea, the stable inheritance of Bt gene in offspring and the absence of fitness cost were detected, transgenic oilseed rape had no competitive advantage. Moreover, Bt-transgenic B. napus could protect B. juncea from insects. Therefore, it is not easy for Bt-transgenic B. napus to invade into the wild B. juncea populations.