Effect Of Transgenic Bt Gene Rice On Soil Nematodes

Rice is one of the staple food in the world. Transgenic Bt gene rice is a high yield new varieties of using modern biological technology to breed, it can reduce pests and increase rice yield, which has broad application prospects. But we must evaluate its biological safety before it is widely used in the production. In the process of transgenic Bt gene rice planting, whether it impacts soil organisms and their ecological function, it becomes one of the major probiem about transgenic Bt gene rice’environmental safety. Nematodes are the most abundant metazoan in farmland soil, as the target to evaluate the effect of transgenic Bt gene rice on soil ecosystem and discuss soil ecological security problems of transgenic Bt gene rice. This paper use the model animal Caenorhabditis elegans (c.elegans)and farmland soil nematodes community as the research object, evaluated the toxicity of Bt toxic protein (Cry1Ac) on single species and the influence of transgenic Bt gene rice on soil nematode community, and provided data support about transgenic Bt gene rice environment safety evaluation system and the oretical basis about of transgenic Bt gene rice production and management commercialization. The main results were as follows:The effect about Bt toxic protein on c.elegans:c.elegans exposured in100or250mg·l-1Cry1Ac protein solution for24h and48h, although the mortality rate is significantly higher than the control group, reached less than25%, this result suggested that Bt protein didn’t affect nematodes’lethal obviously; When treated for48h in50mg·l-1concentration of CrylAc protein, the growth rate of c.elegans was significantly lower than the control group, when the restrain is released, c.elegans’ growth can be compensated; When treated for24h in10mg·1-1concentration of CrylAc protein, the number of eggs and offspring of c.elegans were significantly lower than that in control group, which showed the effects of Bt toxic protein to nematodes fecundity is sensitived to the growth indicators. Both growth effect of Bt toxic protein and breeding effect concentrations were lower than the release concentration about transgenic Bt gene rice (hizosphere soil:0.6ng/g; litter:5ug/g), thus, in the field, transgenic Bt gene rice will not influence on the growth and reproduction of soil nematodes.The effects of transgenic Bt gene rice on soil nematode community:In potted experiments and field experiment, there were not significant difference between the two kinds of soil nematodes genus number, density, species diversity (Shannon diversity, Pielou evenness and Simpson dominance index), function index (MI index and structure index and the concentration index, etc.)and community structure of the transgenic gene rice (KF8) and non-transgenic gene rice (MH86), the above results show that in short-term planting transgenic gene rice will not change the soil nematode diversity and community structure of farmland ecological system, also does not change the functional characteristics of soil ecosystem; Potted experiments showed that the bacterivores’ ratio of transgenic gene rice tended to increase, the herbivores’ratio tended to go down, nutrition diversity of transgenic gene rice was slightly higher than the non transgenic gene rice, but the difference was not significant in the field experiment, thus we speculated that transgenic gene rice could have an impact in the nutrition structure and diversity of nematode, but this effect is not significant on the large scale of farmland ecological system.