Effects Of Transgenic Corn On Soil Microbe

Genetically transgenic crops were first commercialized in 1996 and their use has rapidly expanded in the global.The ecological environmental safty risk increasingly become the attention focus.The experiments were conducted to assess effects of transgenic corn on soil microbial diversity,structure and communities in pot cultivation condition in Yunccheng city,Shanxi province,basing on plate culture method,soil enzymes and high throughput sequencing methods.Transgenic Bt corn hybred P1498 and near-isogenic Non-Bt P1498 line,and transgenic herbicide tolerant corn C31 were used in 2014 and 2015.The results are as follows:1.The results indicated there were no significant differences in soil bacteria,ammonifying bacteria and aerobic azotobacte.Fugal population in P1498 and C31 had significantly decreased by 14.3%and 25.8%in seedling stage in 2014,compared with near-isogenic Non-Bt P1498,respectively.Actinomycetes in C31 had district difference with P1498 and Non-Bt 1498 in tasseling stage in 2014.There were no district differences between treatments at other growth stages These indicated transgenic corn did not affected soil microbal population.2.Two years results showed transgenic corn had no significant effects on soil urease activity.In 2014,transgenic corn varieties had no significant effects on soil catalase,invertase and alkaline phosphatase activities,compared with Non-Bt P1498.But there were district differences in the enzymes at some growth stages in 2015.For example,alkaline phosphatase in P1498 and C31 soils significantly decreased by 7.81%and 5.37%at seedling stage,compared with Non-Bt P1498,respectively.P1498 and C31 Significantly increased soil invertase activity at seeding,heading,maturity stages in 2015.Catalase activity in P1498 significantly increased by 14%at filling stage compared with Non-Bt P 1498.There were no district differences between treatments at other growth stages.3.High throughput sequencing analysis showed 2258,1704 and 1866 OTUs were detected in soil bacterial communities in seedling,heading and harvest stages,OTUs shared 55.22%,43.02%and 25.72%,respectively.Twenty and seven phylum,57classes,441genus and unclassified bacteria were detected in soils.Dominant phylum were Proteobacteria,Planctomycetes,Chloroflexi,Actinobacteria,Acidobacteria,Gemmatimonadetes,Gemmatimonadetes,Bacteroidetes,Firmicutes,Cyanobacteria,Armatimonadetes in all soils.Soil bacteria Chaol in transgenic corn P1498 was higher than Non-Bt P1498 and C31 at seedling and harvest stages,but soil bacteria Chao1 followed in order:Non-Bt P1498>P1498>C31 at tasseling stage.Different transgenic varieties had unique populations,but their relative abundance was very low.The Shannon index showed soil bacteria diversity in transgenic corn P1498 and C31 were higher than Non-Bt P1498 at seedling,and tasseling stages,but bacteria diversity followed in order at harvest stage:P1498>Non-Bt P1498>C31.These results showed transgenic corn had significantly affeced soil bacteria community structure and diversity.