The Research About Impacts Of EPSPS&GAT Transgenic Herbicide-resistant Soybean On Soil Prokaryotic Microorganism Communities

With the development of plant transgenic technology,more and more genetically modified(GM)crops have been.The cumulative area of global GM crops has reached 2 billion hectares,in which the cultivation area of GM soybean is the largest.Although the transgenic soybean varieties have brought great economic and social benefits to society,its environmental problems including the impact on the diversity of soil microbes have gradually attracted worldwide attention.In the soil and plants interaction system,on one side,the soil rhizosphere microorganisms undoubtedly play a very important and irreplaceable role.on other side,plant species strongly influence the diversity of rhizosphere microorganisms.Therefore,it is necessary to research the impact of the exogenous genes and expression products of GM soybean on rhizosphere microbial community,including soil nitrogen fixationbacteria.Experimental field and tested soybeans:The EPSPS&GAT transgenic herbicide-tolerant soybeans ZH10-6,its acceptor soybeans Zhonghuangl0(or simply ZH10),were planted at the Shungyi experimental base in BeiJing.Research contents:We measured soil physical and chemical properties,nitrogen content,soil carbon and nitrogen cycling-related enzyme activity of surrounding soil,we also measured soil nitrogen-fixing bacteria diversity,nodulation effect of the nitrogen-fixing bacteria group,and nitrogen-fixing bacteria abundance of different soybean rhizosphere soil via quantitave PCR of nifH.Besides,high-throughput sequencing of 16S rDNA(V4)amplicons has been performed for clarifying the impact of the EPSPS&GAT transgenic herbicide-tolerant soybeans ZH10-6 on the rhizosphere bacterial diversity compared to its acceptor soybeans ZH10.Main results:1.Our experimental data showed that there were no significant differences in the C or N content of soil and plants,soil nitrogenase activity,nodule nitrogenase activity,and the diversity of culturable nitrogen fixing bacteria.Additionally,no significant difference in the relative abundance of rhizosphere nitrogen-fixing bacteria,which was characterized by quantitative real-time PCR of nifH gene,between the EPSPS&GAT transgenic herbicide-tolerant soybeans ZH10-6 and its acceptor soybean ZH10at different developmental stages,except that there was a significant difference in the relative abundance of nitrogen-fixing bacteria in the surrounding soil between the transgenic ZH10-6 and its acceptor ZH10 at flowering stage.2.Analysis of 16S rDNA(V4 region)amplicons high-throughput sequencing data showed there were no significant differences in most of indices of alpha diveristy between the surrounding soil,rhizosphere soil and roots endophyte of the transgenic line ZH10-6 treated by water or glyphosate herbicide and those of its acceptor ZH10 treated by water only at seedlings,flowering,and pod-setting stage except the simposon index at pod-setting stage.Furthermore,based on the results of PCA,PCoA,and NMDS,there were also no significant differences in beta diveristy between the surrounding soil,rhizosphere soil and roots endophyte of the transgenic line ZH10-6 treated by water or glyphosate herbicide and those of its acceptor ZH10 treated by water at there developmental stage.Conclusion:Based on the above data analysis,the cultivation of the EPSPS&GAT transgenic herbicide-tolerant soybeans or treated once by glyphosate basically had no significant impact on soil rhizosphere microbial communities during the single growth season.In addition,the above conclusion need to be confirmed by more field experiment at different location due to poor field management in this year.