转BT+CPTI基因抗虫棉的种植对土壤根际反硝化菌丰度和多样性影响

Effects of planting transgenic Bt + CpTI cotton on rhizosphere denitrifier abundance and diversity

【目的】为评价转基因棉花的种植对根际土壤反硝化细菌丰度和多样性的影响,【方法】以转Bt+CpTI基因抗虫棉(SGK321)及非转基因亲本棉花石远321(SY321)根际土壤反硝化细菌为研究对象,分别在种植前和棉花的不同生长时期(蕾期、花期、铃期和絮期)取样。采用实时荧光定量PCR方法和末端标记限制性片段多态性(T-RFLP)技术对土壤中反硝化细菌的功能基因nosZ基因进行定量和多样性分析。【结果】结果发现随棉花不同生长时期两种棉花根际土壤中的反硝化细菌丰度均发生显著变化,但变化趋势不同。转基因棉花根际土壤反硝化细菌从种植前的3.12×106copies/g dry soil一直增加到铃期的2.81×107copies/g dry soil,增加了8倍。非转基因棉花根际土壤反硝化细菌丰度变化受生长周期影响更为显著,表现为蕾期增加,花期降低,铃期又增加的趋势。典范相关及部分典范相关分析反硝化细菌多样性结果表明其多样性受环境因素pH、硝酸根浓度以及棉花生长时期(蕾期和花期)影响最为显著,但此外棉花品种也起到了非常重要的作用,【结论】反硝化细菌的丰度和多样性既受棉花生长时期的影响,同时也受棉花品种的影响,转基因棉花通过调节根际土壤中的pH和硝酸根浓度,来影响其多样性和丰度。转Bt+CpTI基因抗虫棉的种植增加了土壤pH,从而导致根际土壤反硝化细菌的多样性和丰度增加。

[ Objective ] To evaluate the effect of planting genetically modified cotton on soil denitrifer. [ Methods ] The impact of transgenic Bt ＋ CpTI cotton （SGK321） and its receptor cotton （SY321） on rhizosphere denitrifier abundance and diversity were investigated by using quantitative PCR （qPCR） and terminal restriction fragment length polymorphism （T-RFLP）. We collected rhizosphere soil before cotton planting （Pre） and along with the cotton growth stage （budding, flowering, belling and boll opening）. [ Results] The abundance of denitrifier in both cottons changed significantly across the growth stage, but the variation tendency was different. In the rhizosphere of transgenic cotton, the denitrifier abundance increased from 3.12 × 10^6eopies/g dry soil （Pre） to 2.81 × 10^7copies/g dry soil （belling）. The denitrifier abundance in non-transgenic cotton was signifcantly affected by the growth stage： increased at budding, decreased at flowering, and then increased at belling. Canonical correspondence analysis and partial canonical correspondence analysis show that the denitrifier diversity was more correlated with pH, concentration of NO3- and budding and flowering. Additionally, cotton genotype was an important factor of influencing the diversity of denitrifier. [ Conclusions] This indicates the abundance and diversity were influenced by both the cotton growth stage and the cotton genotype by adjusting the soil pH and concentration of NO3 -. Planting of transgenic Bt ＋ CpTI cotton leads an increase in the soil pH, which results in an increase in abundance and diversity of denitrifier.