| Based on the priority of environmental and food safety assessment of genetically modified (GM) crops in our country and the relevant national projects that we have undertaken, the following three important issues are studied and reviewed in this thesis that include:1. Transgene flow to hybrid rice and wild relativesRice is one of the most important staple foods in China and GM rice with insect; disease and herbicide resistance have been extensively developed which are in the pipeline readily for commercial application. Therefore, it is urgently needed to study the transgene flow and its possible environmental impact. We have chosen Guangzhou as an experimental site to represent Southern China rice growing area to study gene flow from transgenic rice. The experiment was conducted in a 2.4 ha isolated field mimic rice production practice with pollen competition. A japonica GM rice L201 containing bar gene with herbicide Basta resistance was used as a pollen donor and six indica hybrid rice varieties and its male sterile (ms) lines and two common wild rice (Oryza rufipogon and O. nivara) that share same AA genome with cultivated rice were used as recipients. Results shown that: (1) In the case of parallel plantation of donor and recipients (0 meter zone), the frequency of gene flow from transgenic rice to ms lines (3.145%-36.115%) was significantly higher than that of the hybrid rice varieties (0.036%-0.045%) with 2-3 magnitude difference. (2) Gene flow frequency was reduced as distance from pollen donor increased and a dramatic reduction occurred at about 2 meters. The maximum distance where gene flow was not detected was 50 m for hybrid rice while it was 70 m for ms lines, with an exception that in one of the four ms lines it was detected a frequency of gene flow 2.8+10-6 at 150 m for Zhong 9A. (3) Under side by side plantation, the frequency of gene flow from cultivated rice to common wild rice was found to be 2.162%-7.598%, indicating there exists a relatively high degree of genetic change between them under natural conditions. Based on data generated, we classify 8 recipients into three categories in terms of possible environmental impact: (1) Low risk of gene flow to common cultivars; (2) Intermediate risk to common wild rice with same AA genome; (3) High risk to ms lines.2. Development of a specific database for toxin and anti-nutrient proteinsBioinformatics is a very useful tool for risk assessment of GM foods. To date there is no specific database for toxin and anti-nutrient proteins. In order to establish such a database, we have collected data from some nucleotide and protein database available at present. Totally, 1033 toxin proteins, including 172 from plants, 251 from animals, 577 from bacteria and 42 from" other organisms, as well as 1013 lectins and 391 proteinase inhibitors are collected. This specific database will provide useful information for analysis of substantial equivalence of GM foods with its traditional counterparts in two aspects: (1) providing information on whether there is any toxinor anti-nutrient proteins existed in traditional crops; (2) providing information on homology comparison of ammo acid sequence coding by target gene(s) with known toxin proteins or anti-nutrient factors to predict whether there is any possible risk for transgenic crops and its products.3. Labeling policies and regulations for GM products in different countries and territories and transgene detection method in GM productsUp to December 2002, more than 40 countries and territories have adopted a variety of labeling regulations for GM products. Different labeling policies are not based on the scientific risk assessment, rather it lies on different political, economic and trade considerations. In this paper, labeling regulations in different countries and territories are reviewed including: the type and scope, the threshold level and exemption, the content of labeling, and the negative labeling for non-GM products. The problems and potential impacts of labeling system on GM products...
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