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The isolation distance required for field trials of genetically modified (GM) rapeseed varies widely worldwide, with a 50–400 m distance in most nations contrasting with a minimum 1000-m isolation distance in China. The goal of this study was to evaluate the relevance of current regulations in China regarding the isolation distance needed for GM rapeseed trials. A pollen flow experiment was conducted based on the design of concentric circles, with the GM plants in a 20-m diameter circle at the centre, surrounded by non-GM plants to a distance 60 m from the perimeter of the circle containing GM plants. The rate of pollen flow was the highest at the isolation distance of 0.5 m, where it ranged from 2.3091% to 2.6711%. The general pattern of the pollen flow rate (y) with distance (x) was well described by the equation y = 1.3936x-0.9136 (R 2 = 0.9950). The long-distance pollen flow tested at the isolation distance of 800 m was 0.0018%, which agrees with the theoretical prediction. The results suggested that 300 m, rather than 1000 m, is a reasonable distance to ensure a tolerable threshold of pollen flow (less than 0.01%) under conditions of winter rapeseed production in China.

Evaluating exogenous protein expressed in transgenic crops is one of the most effective methods of assessing the safety of transgenic plants. The objective of this study was to assess the food safety of genetically modified (GM) rice containing a lysine-rich fusion protein gene (transgenic GL gene rice) by in vitro digestion and acute toxicity testing of exogenous protein, according to the national standard of the People’s Republic of China. The exogenous protein was rapidly degraded in the simulated gastric and intestinal fluids. In the acute experiment, the exogenous protein was injected into Institute of Cancer Research (ICR) mice via the tail vein at a dose of 438 mg kg−1 body weight. No adverse effects on animal behavior or mortality were observed during the following 15-day period and there were no significant biological changes in body weight, serum biochemistry parameters, relative organ weights or histopathological examinations, compared with the control group. Therefore, exogenous protein in transgenic GL gene rice has a low potential allergenicity or toxicity risk.