| Since the birth of genetically modified crops,their global commercial cultivation has developed rapidly,people had began to concern about ecological risk safety.Therefore,the assessment researches on ecological risks of genetically modified crops has gradually become a research focus.The soil microorganism reflects the change of soil quality,which can be used as an index of soil health.The pot experiments were conducted to evaluate effects of the transgenic soybean on soil microorganisms for two years basing on microbial plate culture method,soil enzymatic and high-throughput sequencing method.Herbicide resistant transgenic soybean TN1 and 94Y20 and non-transgenic soybean Yun101 were used and analyzed soil microbial community structure and diversity,soil enzyme activity for environment risk evaluation of genetically modified crops.The main results are as follows:1.Compared with non-transgenic soybean Yun101,the two transgenic varieties had no effects on soil bacteria at seedling stage and flowering stage,the number of bacteria in the transgenic soybean was significantly lower than that in the ordinary soybean at the drum grain stage,Yun101 was significant different between with 94Y20,but not with TN1 at mature.There were no obvious difference for soil fungal numbers between transgenic soybean varieties and non-transgenic Yun101 at seedling stage,grain drum stage and mature stage,but the transgenic variety 94Y20 significantly decreased compared with Yun101 and TN1.Transgenic soybean TN1 and 94Y20 revealed no obvious differences on soil actinomycetes with Yun101 at different growing stages.The two transgenic varieties had significantly affected soil nitrogen-fixing bacteria and soil ammoniating bacteria at the seedling stage,but had no significant difference at other growing stages.These indicated that herbicide-tolerant transgenic soybean had a little effects on soil microbial population.2.The two-year experiment results showed that the soil urease and alkaline phosphatase activity of transgenic soybean were not significantlyaffected at different growing stages.In the first year,the two transgenic soybeans had no significant effect on the activity of sucrase;in the second year,the effect of transgenic soybean on soil sucrase activity was not significant in the seedling and flowering stage,but the soil sucrase activity was significantly increased in the drum grain and mature stages.In the first year,soil catalase activity in transgenic soybeans were not significant at all stages,but soil catalase activity in the second year were obviously affected.These indicated that transgenic soybeans had some effects on soil at the growing stages.3.There were 1442 bacterial OTUs dectected in the three soils,and84.81% the OTUs were shared in all soil samples.All soil samples were detected 29 phyla and 371 genera.Proteobacteria was the most abundant phylum in all soils.Higher relative abundant phylum were Cyanobacteria in transgenic soybean 94Y20 and TN1,Proteobacteria,Acidobacteria,Chloroflexus and Planctomycetes,in non-transgenic soybean Yun101 soil.Unique community was found in each soil,Sacchairibacteria in the transgenic soybean 94Y20 and TN1,Microgenomates in non-transgenic soybean Yun101,but their abundance was minor.The results revealed that transgenic soybean changed the soil bacterial community structure and diversity.There were 118 fungal OTUs dectected in the three soils,and 61.86%the OTUs were shared in all soil samples.All soil samples were detected 25 phyla and 63 genera.Ascomycota was the most abundant phylum in all soils.Higher relative abundant phylum were Ascomycota in non-transgenic soybean Yun101 soil Ciliophora,norank_k__Amoebozoa,Choanoflagellida,unclassified-d-Eukkaryota and no rank_d__Eukaryota in.Transgenic soybean94Y20 and TN1 soils Unique community was found in each soil,Tubulinea and LKM15 in the transgenic soybean 94Y20,Entomophthoromycota in non-transgenic soybean Yun101,but the abundance was minor.The results revealed that transgenic soybeans changed the soil fungal community structure and diversity. |
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