Abstract: 【Objective】 Genetically modified (GM) plants have been widely used in both agriculture and food industry. A scientifically sound environmental risk assessment, including weediness risk, is required for crops derived from genetically modified prior to unrestricted release into the environment. The objective of this study was to assess the potential ecological risk for weediness of transgenic drought-tolerant wheat MGX-L, and to provide scientific data for the formulation of evaluation standard of environmental safety assessment of transgenic wheat in China. 【Method】 In the cultivated lands and abandoned lands, the surviving competition ability of transgenic drought-tolerant wheat MGX-L, recipient variety and conventional wheat varieties were comparatively evaluated by investigating their agricultural traits. The propagation coefficient of wheat planted in abandoned lands was compared and the survival ability in abandoned lands was evaluated. Volunteer possibility, seed shattering and persisting possibility of transgenic drought-tolerant wheat MGX-L were analyzed and compared with the wild type for evaluating the ability of life continuous. The reproducing ability was evaluated by comparing the pollen viability, pollen diameter and sterility of MGX-L with the wild type. The weediness potential of MGX-L was evaluated based on the above results.【Result】There were no significant differences between transgenic wheat MGX-L and the wild type in plant height, spike number per hectare and per spike grain. The 1000-grain weight and yield of the transgenic wheat MGX-L were higher than that of the recipient variety Jimai 22. However, the 1000-grain weight and yield of the transgenic wheat MGX-L were lower than that of conventional wheat varieties or no significant difference. There were no significant differences between transgenic wheat MGX-L and the wild type in survival ability in the cultivated lands. Some wheat seeds could geminate and obtain seeds of next generation in abandoned lands. However, its propagation coefficient was less than 1 and the population size of transgenic wheat declined after the first year as a result of increased competition from native perennial plants. The transgenic wheat population couldn’t persist in abandoned lands like its conventional counterpart. There were no significant differences in seed shattering ability and volunteer plants rate between the transgenic wheat and the wild type. When buried under soil 20 cm, the seeds of transgenic wheat and the wild type were all rotted. When buried under soil 3 cm, the seeds of transgenic wheat and the wild type were rotted or sprouted. There were no intact seeds buried under soil. So there was no significant difference between the transgenic wheat and the wild type in seed persisting ability. 【Conclusion】 It was concluded that the transgenic drought-tolerant wheat MGX-L had the lowest potential weediness like the non-transgenic wheat varieties, based on the assessment of survival ability, seed shattering ability, volunteer plants rate and seed persisting ability.

Key words: transgenic drought-tolerant wheat, weediness, safety assessment