Effect Of Transgenic BT-Maize With Cry1Ie Gene On The Structure And Functional Diversity Of Rhizosphere Microbial Communities

Since the commercialization of genetically modified(GM)crops,the planting area of GM crops has increased dramatically.Although the GM crops has brought great benefits to the global environment and economy,the impact of GM crops on environmental safety has also attracted widely public attention,especially on the soil ecosystems.In addition,the release of transgenic plants under field conditions may affect the soil functional enzymes and soil microbial communities.The release of GM crops may have potential effects on the enzyme activities and microbial community.In soil ecosystems,Soil microorganisms were an important component of ecosystem diversity,offering most biological diversity,and had an important impact on plant diversity and productivity in ecosystems.The transgenic BT maize IE09S034 with crylle gene and its non-transgenic maize counterpart Zong31 were used in this study.The aim was to analyze the effect of the transgenic BT maize IE on the soil physicochemical properties,enzyme activities,functional diversity of microbial community and the structure of the bacterial communities in rhizosphere soil.The study lasted two years.The transgenic BT maize IE and its non-transgenic parental maize IECK were provided by institute of crop of CAAS(Chinese academy of agricultural science).This study was performed at Changchun(43°30'N,124°49'E),Jilin Province.A completely randomized block design was set out in 2014 and 2015.Soil samples were collected in 2014 and 2015(the first and the second year of the experiment)3 times at seeding stage(SS),flowering stage(FS)and maturing stage(MS)of the maize.The main results were as follows:1.Effect on the soil physicochemical properties and enzyme activities.The soil moisture,pH,C and N contents,Urease and Phosphatase activities in rhizosphere soil were measured to detecting the effect on the soil physic-chemical properties and enzyme activity.The results showed that:no significant differences were observed in these properties between IE and IECK.It means that,the release of the transgenic BT maize IE had no significant impact on the soil physicochemical properties and enzyme activities.2.Effect on the functional diversity of the microbial community.The Biolog ECO micro-plates were used in this study to test the functional diversity of the microbial communities in rhizosphere soil.The results indicated that there was no significant difference on the average well color development in Biolog ECO micro-plates,the diversity and the substrate utilization patterns of the microbial communities in rhizospheric soil between IE and IECK.So the transgenic BT maize IE had no effect on the functional diversity of the rhizosphere soil microbial communities.3.Effect on the structure of the bacterial community.A pyrosequencing of the bacterial 16S ribosomal RNA gene was used to detect the effect of transgenic maize on the structure of the bacterial community.The results showed that the taxonomic structure and the diversity of the bacterial community in rhizosphere soil were similar between IE and IECK.This proved that the transgenic BT maize IE had no effect on the structure of the bacterial community.In summary,the transgenic BT maize IE had no apparent impact on the structure and functional diversity of rhizosphere microbial communities.These results enriched our understanding on the biosafety of the GM crops with cry1Ie gene.