摘要:转基因作物可能通过根系分泌物和植株残体组成的改变及外源基因的转移释放令土壤微生物群落产生变化，影响土壤微生物的生态功能。氨氧化细菌和反硝化细菌是驱动土壤硝化和反硝化过程的关键微生物，其群落结构的变化直接关系土壤氮素的转化与利用。本研究利用荧光定量PCR和PCR-DGGE技术分析了转cry1Ac/cpti双价抗虫基因水稻‘Kf8’秸秆还田降解过程中，土壤氨氧化细菌和反硝化细菌群落丰度与组成的变化，探讨转基因水稻是否存在影响稻田土壤氮素转化与N2O排放的可能。结果显示：无论是氨氧化细菌amoA基因还是反硝化细菌nirS基因，其丰度在转基因水稻‘Kf8’与非转基因水稻‘Mh86’的秸秆还田土壤中都没有显著差异；转基因水稻‘Kf8’和非转基因水稻‘Mh86’秸秆还田降解过程中0~10 cm土层中的amoA基因丰度均显著高于10~20 cm及20~30 cm土层（P < 0.05）；各深度土层中的nirS基因丰度均存在随秸秆还田时间延长而增加的趋势。水稻秸秆还田降解过程中，转基因水稻‘Kf8’的土壤氨氧化细菌和反硝化细菌的群落多样性指数及组成，均与非转基因水稻‘Mh86’没有显著差异。相关分析结果表明土壤氨氧化细菌和反硝化细菌群落组成均与水稻秸秆还田时间存在显著相关性（P=0.002），反硝化细菌群落组成还与土层深度显著相关（P=0.024）。本研究表明转cry1Ac/cpti抗虫基因水稻秸秆还田对稻田土壤硝化和反硝化关键微生物群落不会产生明显影响。就土壤微生物群落而言，转cry1Ac/cpti抗虫基因水稻秸秆还田不存在影响土壤氮素转化与N2O排放的可能。
关键词:转基因水稻/
秸秆还田/
氨氧化细菌/
amoA基因/
反硝化细菌/
nirS基因/
群落结构
Abstract:The cultivation of genetically modified plants may have the potential to alter microbial community structure and function in soils through root exudates and plant residues. Ammonia-oxidizing bacteria or denitrifying bacteria are the key microbes for nitrification or denitrification. A change in community structure of ammonia-oxidizing bacteria or denitrifying bacteria can affect the conversion and utilization of nitrogen in soil. The purpose of this study was to explore the possibility of transgenic rice to induce change in nitrogen transformation and N2O emission in paddy soils. In the study, the abundance and composition of ammonia-oxidizing bacteria or denitrifying bacteria in paddy soils under straw return to soil under cry1Ac/cpti transgenic gene rice 'Kf8' or non-transgenic rice 'Mh86' were analyzed by real-time PCR and denaturing gradient gel electrophoresis (DGGE) based on amoA gene or nirS gene. The results showed that there were no differences in the abundance of amoA gene or nirS gene in the soil with returned transgenic rice 'Kf8' straw and non-transgenic rice 'Mh86' straw. The abundance of amoA gene in the 0-10 cm soil layer was significantly (P < 0.05) higher than that in the 10-20 cm and 20-30 cm soil layers under degraded transgenic rice 'Kf8' straw or non-transgenic rice 'Mh86' straw. The abundance of nirS gene in the soil increased with the time of returned straw to soil for either transgenic rice 'Kf8' or no-transgenic rice 'Mh86'. At the same time, the Shannon-Weiner index and composition of ammonia-oxidizing bacteria or denitrifying bacteria in the soil under degraded transgenic rice 'Kf8' straw were similar to those under degraded non-transgenic rice 'Mh86' straw. The composition of ammonia-oxidizing bacteria in the soil was significantly correlated with the time of rice straw return (P=0.002). Also the abundance of denitrifying bacteria was significantly correlated with the time of rice straw return (P=0.002) and depth of soil (P=0.024). The findings demonstrated that there was no significant effect of returned cry1Ac/cpti transgenic rice straw to soil on key microbial com-munities for nitrification or denitrification in soil. In terms of soil microbial community, there was no signiifanct effect of returned cry1Ac/cpti transgenic rice straw to soil on nitrogen transformation and N2O emission in paddy soils.
Key words:Transgenic rice/
Straw return/
Ammonia-oxidizing bacteria/
amoA gene/
Denitrifying bacteria/
nirS gene/
Community structure
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