The Research About Impacts Of EPSPS Transgenic Herbicide-resistant Maize On Soil Prokaryotic Microorganism Communities

Since 1996,genetically modified(GM)crops have been commercially applied in the world,and have brought great economic benefits.Maize is the largest food crop in China and accounts for one-third of Chinese crop production,but it still is faced with a shortage of supply.The composition,structure and diversity of soil microbial community are important indicators to measure soil ecosystem,because soil microbes,especially rhizosphere microbes,play the crucial roles on affecting plant health and growth;in turn,plant species also strongly influence the diversity of rhizosphere microbes via root exudates.Therefore,it is the important evaluation of the environmental safety to study the impact of GM crops including GM maize on the soil rhizosphere microbes.Experimental field and tested maize:The EPSPS transgenic herbicide-tolerant maize CC-2 and its acceptor maize Zhengdan 958(or simply ZD958)were planted in Jinan,and samples were collected at flowering stage;the EPSPS transgenic maize CC-2 and its acceptor maize ZD958 were also planted in Zhengzhou,and samples were collected at Tasseling stage.Research contents:Soil physicochemical properties of surrounding soil of different maize and bulk soil were measured;carbon and nitrogen content,soil carbon and nitrogen cycling-related enzyme activity of surrounding soil and bulk soil were also detected.We also measured the quantity of culturable rhizophere soil nitrogen-fixing bacteria.Furthermore,metagenomic DNA were isolated from rhizosphere soil,surrounding soil and bulk soil of transgenic maize CC-2 and its acceptor ZD958 at flowering or tasseling stage,then high-throughput sequencing of 16S rDNA(V3-V4 region)amplicons was performed by Illumina Miseq platform.Main Results:1.The experimental data of Jinan planting point showed that there was no significant difference in soil C?N content,physical and chemical properties,soil enzyme activity between the surrounding soil of the EPSPS transgenic maize CC-2 and those of the acceptor maize ZD958 at flowering stage.There was also no significant differences between the rhizophere soil of the transgenic maize CC-2 and that of the acceptor ZD958 at flowering stage.2.The experimental data of Zhengzhou planting point indicated that there was no significant difference in soil C?N content,physical and chemical properties,and the enzyme activity of soil urease,nitric acid reductase,nitrite reductase and nitrogenase between the surrounding soil of the EPSPS transgenic maize CC-2 and that of the acceptor maize ZD958.But there was a significant difference in the quantity of culturable nitrogen-fixing bacteria between the rhizosphere soil of transgenic maize and that of the acceptor.3.Based on the analysis of the high-throughput sequencing data of 16S rDNA(V3-V4 region)amplicons,we found that there were no differences all indices of alpha diversity between the surrounding soil and rhizosphere soil of the EPSPS transgenic maize CC-2 and those of its acceptor ZD958.Additionally,based on the results of PCA and PCoA,we found that there were also no significant differences in beta diveristy between the surrounding soil and rhizosphere soil of the EPSPS transgenic maize CC-2 and those of its acceptor ZD958.Finally,there were also no significant differences in the relative abundances of different taxonomic composition between the rhizosphere soil of the EPSPS transgenic maize CC-2 and that of its acceptor ZD95 at tasseling or flowering stages,based on the contrast analysis of the surrounding soil of the EPSPS transgenic maize CC-2 and those of its acceptor ZD958.Main Conclusion:Based on the above results,at flowering or tasseling stage,the cultivation of the EPSPS transgenic maize CC-2 basically had no significant effect on soil rhizosphere bacterial communities during the single growth season.