| With the increasing concern of genetically modified plants (GMP), more and more researches are focused on the ecological safety of GMP. Soil is the important media where the transformation and exchange of biological substance and energy occur. The health of soil ecological system concerns the normal matter cycling and macro-and micro-bioecology all over the ecolosystem. The GMPs grow in the soil and the target protein can get into the soil system with root exudates or residual release. Hence, the analysis of the potential impacts of GMp on soil ecology is gaining a large attention. This report mainly concerned the effect of transgenic rice with constitutive expression of chitinase (RCH10) and glucanase(Glu) on soil animals in 3 experimental systems with the nontransgenic wild type as control. The soil adopted was typical rice paddy soil in Shanghai region. Soil indication animals included collembolan Folsomia candida, Folsomia fimteria,Sinella curviseta and enchytriedes E.crypticus. The expression level and enzymic activity of transgenic rice were evaluated by Northern blot, Western blot and the enzyme reaction. The 3 experimental systems were: (1) Petri dishes with substrates made of plaster Paris and chacor: the test synchroniced collembolans were fed with fresh transgenic rice seedling (growing for 3 weeks) for 21 days; (2) soil-litter microcosm systems for single species test: the synchroniced collembolans and adult enchytrides were respectively exposed to the mixture of soil and harvested dry residues, and then the systems were incubated for 21 days; (3) soil-litter mesocosm systems for multi-species test: 3 species of collembolans and one species of enchytrides were put in one mesocosm with mixture of soil and harvested dry residues, and then the systems were incubated for 16 weeks. Similar tests with pesticide was as a positive control. The results showed: (1) After 21 day exposure to young plant, the reproduction of F. candida fed with transgenic leaves and roots was significantly reduced by 45.5% (p < 0.05) and 30.51% (p < 0.05), respectively, compared to the control non-transgenic wild rice seedlings, while there was no statistic difference of the reproduction of F. fimetaria between the treatments with transgenic and non-transgenic rice. (2) In soil-litter microcosm system for single species, there was a weak reduction by 19.34% (p < 0.05) of the reproduction of F. candida by transgenic mature dried residues in amounts corresponding to 30 g plant material kg-1 soil, while no significant difference in the reproduction of F. fimetaria or E. crypticus was found between transgenic and non-transgenic treatments. (3) in soil-litter mesocosm systems for multi-species: compared to non-transgenic control, the reproduction of F. candida was significantly reduced by 19.35% by transgenic rice residues corresponding to the concentration of 30g/kg soil after 16 week incubation, while no significant difference of the reproduction was found between transgenic and non-trangenic rice treatments after 8 week incubation; likewise, the reproduction of enchytrade E.crypticus was significantly reduced by 56.60% and by 38.03% after incubation of 8 and 16 weeks, respectively. On the contrary, the reproduction of collembolan S. curviseta was significantly increased by 113.21% and 84.78% after incubation of 8 and 16 weeks, respectively; there was no significant diffrence of F. fimetaria reproduction between the transgenic and non-transgenic rice treatments. In the pesticide positive control experiment, reproduction of F. candida was reduced linearly with concentration of the pesticide.Through this study, the risk assessment on transgenic rice by soil animals test was primarily established in laboratory, which contributed to standardized method establishment and subsequent field studies. This study also provided a new way for risk assessment of transgenic plant in soil ecosystem. Soil is an important ecosystem for matter cycling and energy transformation, the analysis of specialized soil animal founctional g... |
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