| Now, phytase transgenic corn and transgenic Bt rice had provided an efficient way for improving the efficiency of feed utilization, reducing environmental pollution caused by animal manure and reducing rice losses caused by insect pest, respectively. However, the artificial insertion of exogenous genes, may change the plant genome sequences, affect the plant physio-biochemical characteristics and physicochemical structure, which are dangerous to soil ecosystem. A healthy soil ecosystem is essential for nutrient cycling and energy conversion. The long term planting of phytase transgenic corn and transgenic Bt tice, could change the physical and chemical properties of soil and soil fertility, besides it could cause the Bt toxin accumulation in soil, so that it may influence on soil organisms to varying degrees.In recent years, global environmental change, especially the rise of CO2 concentration, has been an item of great concern for the scientific community. Elevated CO2 concentrations can improve crop photosynthesis and prolificacy, increase the C/N, influence the secondary metabolism defense of plant and will further influence the structure and complexity of soil food web. It has proved that the Bt toxin of transgenic Bt rice grown in elevated CO2 will be reduced. It is obvious that studying the effects of transgenic crops on soil ecosystem will contribute to clarify the environmental safety of transgenic crops and have a sustainable development in the future.In this paper, phytase transgenic corn (BVLA430101) and conventional corn,2 dual-transgenes:restorer (HH1 vs MH63) and hybrid (Bt-SY63 vs SY63) and 1 pure transgenes (KMD vs XSD) were studied under the condition of field and open-top chamber (OTC), in order to clarify the soil environmental safety of transgenic crops through studying the effects of transgenic crops on soil mites and nematodes.The main results are as follows:1.The effects of phytase transgenic corn on soil mites and nematodes under the fieldFrom the conclusion of the field, we know that the abundance of soil mites changed obviously with sampling time, but there was no remarkable difference between phytase transgenic corn and non-transgenic corn. There was no obviously negative impact on soil nematodes, and the abundances of bacterivores and omnivores-predators and total soil nematodes in transgenic corn field during milk-ripe stage were significant higher than those in control corn field by student-T test, which might be related to the observed increase in the nitrogen content of field soil under transgenic corn.2. The effects of transgenic Bt rice on soil mites under the fieldThe results of different lines (restoter HH1 vs MH63 and hybrid Bt-SY63 vs SY63): different lines had different effects on soil mites but the difference were not obvious, the influences of transgenic rice and non-transgenic rice during the same line were also different. In hybride lines, there was significant difference in total abundance, community diversity, eveness and genus richness between transgenic and non-transgenic rice. Compared with the hybrid line, restorer line showed a certain superiority in every indicators, and compared with the non-transgenic rice, transgenic rice of restorer line also showed a certain superiority in every indicators. Therefore, restorer line was more suitable for production than hybrid line.The results of different genes (pure genes KMD vs XSD and dual genes HH1 vs MH63):showed that genes had little effects on mites total abundance and community composition, but it can produce a significant interaction on total abundance with transgenic genes, and this kind of interaction was mainly caused by the pure genes, besides the planting of transgenic rice of pure genes can also generate significant influence on genus richness. There was no negative effect of transgenic Bt rice on soil mites. Compared with transgenic rice of pure genes, the transgenic rice of dual genes showed a certain advantage in every indexes, and had little influences on soil.3. The effects of transgenic Bt rice on soil nematodes under elevated CO2 and temperatureThe results:(1) Bacterivores were the dominant population of the two kinds of rice, the elevated CO2 and temperature can affect soil nematodes genera; (2) All indexes changed obviously with sampling time, the number of soil nematodes between HH and MH had a downtrend with years’ increasing under other treatments except elevated CO2 and low temperature (E-T); (3) Compared with MH, planting transgenic Bt rice had no obvious effect on soil nematode abundance、trophic group and ecological indices, but it can generate significant interactions on herbivores、bacterivores、nematode channel ratio (NCR) and Shannon index with years, and that on bacterivores with years and CO2 concentration. In conclusion, a two-year experiment in simulated global change did not find adverse effects of transgenic Bt rice on soil ecosystem. |
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