转基因苏云金杆菌在环境中的残留和扩散测定

本试验在新疆吉木萨尔县三台镇黄蒿湾村未施过苏云金杆菌(Bacillus thuringiensis)制剂的马铃薯地中,喷施两种转基因苏云金芽孢杆菌粉剂UV1和G0。经过田间土样抽样调查,结果表明,工程菌可在田间存活一年以上,但总体呈现下降趋势,并且土壤中工程菌的数量随田间温度和湿度的变化呈现不断的波动。通过在距试验区不同距离的地点进行取样分析检测,发现工程菌可扩散到距离试验点20 m以内的隔离区。在隔离区外(20 m以外),无论在植物叶片还是在土壤中都未检测到工程菌的存在。

Screening on Synergist of Bacillus thuringiensis Wettable Powder

[Objective] This study aimed to screen the best synergistic material for Bt wettable powder and evaluate their synergistic effect. [Method] The synergism of six different kinds of additives for Bacillus thuringiensis wettable powder （Bt WP） on the 2^nd instar larvae of Plutella xylostella was tested by method of leaf dipping in labora- tory. [Result] The mixtures of Bt with 0.1% ZnCl2, 0.5% ZnCl2, 1.0% ZnCl2, 1.0% MgCI2, 0.5% boric acid, 1.0% boric acid, 0.5% citric acid or 1.0% citric acid all ex- hibited synergistic effect, in which the synergistic effect of mixture containing 0.5% boric acid was the highest, with 17.2 synergistic ratio; followed by the mixture containing 1.0% ZnCl2, with 15.6 synergistic ratio. Moreover, addition of 0.5% boric acid could shorten the median lethal time of Bt wettable powder by about 10 h. After the mixtures of Bt with 0.5% boracic acid or 1.0% ZnCl2 was stored for 15 d at room temperature, toxicities of the two mixtures did not change significantly. [Conclusion] Boracic acid as the synergist of Bt wettable powder could not only increase insecti- cidal effect of Bt, but also accelerate its insecticidal rate. So, boracic acid could improve the disadvantages of Bt wettable powder such as poor insecticidal effect and slow insecticidal speed in a certain degree.

Ecological Consequences of Elevated CO2 and Bt Cotton on Soil Collembola

Transgenic cotton was modified to express a gene derived from the bacterium Bacillus thuringiensis （Bt） to combat agriculturally important Lepidopteran pests. Elevated CO2 is expected to further alter the chemical composition of the plant, and this change may affect the role soil fauna plays in decomposition of Bt plants. A 3 months litterbag field study, consisting of four treatments using leaves from Bt cotton and near-isolines of non-Bt cotton grown under ambient and elevated CO2 levels, was conducted to investigate the abundance and community structure of soil Collembola that developed on the decaying leaf material. A total of 4,884 collembolans, including 13 genera of five families, were extracted in the present study. These results suggest that collembolan distribution was relatively uniform among the Bt cotton, elevated concentration of CO2 and control treatments, except for a significant difference in the densities of Onychiurus and Folsomides. No significant effects were detected in the decomposition rate between the two cotton varieties and two CO2 treatments. These findings indicated that transgenic Bt cotton plants and elevated CO2 do not have any adverse effect on the soil collembolans through the decomposition way in soil ecosystem.

Risk Assessment and Biosafety Studies of Transgenic Bt Rice （Oryza sativa L.）

Transgenic crops having alien genes from different sources are getting popularity. A Rice （Oryza sativa L.） containing gene from Bacillus thuringiensis, a soil bacterium, was assessed to study the potential risks of transgenic plants on environment. The crop was found resistant to target insect pests. Rice variety Basmati-370 transformed with two insecticidal genes, crylAc and cry2A, was grown under field conditions for several years. Data were collected at different stages of the plant growth. Fate of Cry protein in soil, effect of Bt protein on non-target insects, risks of vertical and horizontal gene flow were evaluated. No potential hazard was found at all levels. Bt protein was unstable and degraded significantly in soil within 30 days after harvesting the crop. No harmful effects were found on non-target insects （insects other than order lepidoptera）. Maximum gene flow of 0.02% was observed at close spacing and no evidence of horizontal gene transfer to Rhizobium spp. was found. In conclusion, the transgenic rice plants transformed with Bt genes have no harmful effects on the environment.

Molecular characterization and efficacy evaluation of a transgenic corn event for insect resistance and glyphosate tolerance

A transgenic maize event ZD12-6 expressing a Bacillus thuringiensis （Bt） fusion protein CrylAb/Cry2Aj and a modified 5-enolpyruvylshikimate-3-phosphate synthase （EPSPS） protein G10 was characterized and evaluated. Southern blot analysis indicated that ZD12-6 is a single copy integration event. The insert site was determined to be at chromosome 1 by border sequence analysis. Expression analyses of Bt fusion protein CrylAb/Cry2Aj and the EPSPS protein G10 suggested that they are both expressed stably in different generations. Insect bioassays demonstrated that the transgenic plants are highly resistant to Asian corn borer （Ostnnia furnacalis）, cotton boll worm （Helicoverpa armigera）, and armyworm （Mythimna separata）. This study suggested that ZD12-6 has the potential to be developed into a commercial transgenic line.