转cry1 Ac/cpti基因水稻对土壤氨氧化细菌群落组成和丰度的影响

【背景】氨氧化细菌是驱动硝化作用的关键微生物,其群落多样性变化对土壤氮素转化具有重要意义。转基因作物可能通过根系分泌物和植株残体组成的改变对土壤微生物群落产生影响。【方法】本研究通过田间定位试验,利用特异引物进行PCR-DGGE（聚合酶链反应—变性梯度凝胶电泳）和荧光定量PCR,分析了种植转cry1 Ac/cpti双价抗虫基因水稻第3、4年土壤中氨氧化细菌群落组成和丰度的变化。【结果】水稻各生育期（分蘖期、齐穗期和成熟期）内,转cry1 Ac/cpti基因杂交稻Ⅱ优科丰8号（GM）的土壤氨氧化细菌16S rRNA基因群落组成、多样性指数与其对应的非转基因杂交稻Ⅱ优明恢86（CK）间均没有显著差异;以DGGE条带为基础的氨氧化细菌群落组成的冗余分析（RDA）显示,GM和CK的土壤氨氧化细菌群落组成只与水稻生育期存在显著相关性（P=0.002和0.018）;同时,水稻各生育期内土壤氨氧化细菌16S rRNA基因丰度在GM和CK间也没有显著差异,但均随水稻生长而变化且在齐穗期达到最高（P〈0.05）。【结论与意义】稻田土壤氨氧化细菌的群落组成与丰度在水稻不同生育期存在差异,但在转cry1 Ac/cpti基因水稻和非转基因水稻间没有显著差异,即一定时期内种植转cry1 Ac/cpti抗虫基因水稻不会影响土壤氨氧化细菌的群落组成和丰度。

Effect of cry1 Ac/cpti transgenic rice on community composition and abundance of ammonia-oxidizing bacteria in paddy soil

Background]Ammonia-oxidizing bacteria are the key microbes that catalyse nitrification,and the diversity of ammonia-oxidizing bacterial community has important influence on the transformation of nitrogen in soil.The cultivation of genetically modified plants may have the potential to alter the diversity of microbial community in soil through root exudates and plant residues.Method] In this study,one event of cry1Ac/cpti transgenic rice（GM） and it＇s parental non-transgenic rice（CK） was planted in the same field site for four consecutive years.The community composition and abundance of ammonia-oxidizing bacteria in paddy soil were assessed by denaturing gradient gel electrophoresis（DGGE） and real-time polymerase chain reaction（rtPCR） based on the 16S rRNA gene in the third and forth year after establishment of the experimental field site.Result]The results of redundancy discriminate analysis based on DGGE bands showed that composition of ammonia-oxidizing bacterial community markedly（P=0.002,0.018）changed during rice growth seasons in the third and forth year after establishment of the experimental field site,while no significant differences were observed in community composition of ammonia-oxidizing bacteria between fields with GM and CK,and the Shannon index of ammonia-oxidizing bacterial community in field with GM was similar to that of the non-transgenic control.Compared with non-transgenic plants,the abundance of 16S rRNA gene of ammonia-oxidizing bacteria in paddy soil with cry1Ac/cpti transgenic rice had no changes during rice growth in the third and forth year after establishment of the experimental field site,while it showed large seasonal changes,and was highest（P0.05） in the heading stage of rice.Conclusion and significance]Our field study indicates that the composition and abundance of ammonia-oxidizing bacterial community in paddy soil change with the growth of rice,but the cry1Ac/cpti transgenic rice had no large effect on either the composition or the abundance of ammonia-oxidizing bacterial community in paddy soil during rice growth at least in the short term.