Effects Of BADH Transgenic Maize On Soil Physicochemical Properties And Microbial Diversity

With the rapid development and large-scale planting of transgenic crops,more and more people begin to pay attention to the environmental safety of genetically modified food.The betaine aldehyde dehydrogenase(BADH)gene transgenic maize BZ-136 can effectively tolerate the salinealkaline stress of maize,thereby increasing the yield of maize planted in saline-alkaline soil.The metabolites of transgenic crops may directly enter into soil via root exudates or plant residues,causing certain environmental risks.In this study,a pot experiment maize was planted in neutral and alkaline soil by pot experiment,and rhizosphere soil and maize roots were sampled at seedling stage,elongation stage,flowering stage and mature stage.The differences in physicochemical properties,enzyme activities and bacterial community diversity among transgenic maize BZ-136,parental non-transgenic maize Zheng58 and conventional inbred maize U8112 were determined,and the difference in colonization rate of arbuscular mycorrhizal fungi and the arbuscular mycorrhizal fungi diversity in rhizosphere soil between transgenic maize BZ-136 and parental non-transgenic maize Zheng58 were determined.The following results were obtained in this study:(1)Effect of transgenic BADH maize on soil physicochemical propertiesBZ-136 had a transient effect on soil electrical conductivity,organic carbon and total nitrogen in some growth stages,and the difference was aperiodic.For example,for soil total nitrogen content,compared with Zheng58,BZ-136 was significantly lower at the seedling stage and significantly higher at the elongation stage under neutral soil planting conditions,and BZ-136 was significantly lower than Zheng58 at elongation stage in alkaline soil.(2)Effect of transgenic BADH maize on soil enzyme activitiesThe four growth stages of BZ-136 rhizosphere soil urease activity in alkaline soil were significantly higher than non-transgenic maize from elongation stage to mature stage.The four growth stages of BZ-136 rhizosphere soil alkaline phosphatase activity in neutral soil were significantly lower in non-transgenic maize Zheng58 and U8112 at flowering and mature stage.There was almost no significant difference in the activities of saccharase,catalase,acid phosphatase and neutral phosphatase in the rhizosphere soil,or there was a significant difference only in a certain growth stage.(3)Effects of BADH transgenic maize on soil bacterial community diversityBased on 16 S rRNA high-throughput sequencing of rhizosphere soil bacteria,the composition of bacterial community of the three maize lines was similar.NMDS and cluster analysis based on OTU level showed that the bacterial community structure in rhizosphere soil was significantly affected by agrotype and growth stage.Maize lines had no significant effect on soil bacterial community.(4)Influence of BADH transgenic maize on colonization rate of arbuscular mycorrhizal fungi in rootsIn neutral and alkaline soils,BADH transgenic maize BZ-136 only showed significantly lower colonization rate of hypha,vesicle and total AMF than non-transgenic maize at elongation stage(p < 0.05).ANOVA analysis showed that the transgenic maize had no significant effect on the colonization rate of arbuscular mycorrhizal fungi.(5)Effects of BADH transgenic maize on the community diversity of soil arbuscular mycorrhizal fungiAccording to high-throughput sequencing of 18 S rRNA of arbuscular mycorrhizal fungi in rhizosphere soil,BZ-136 and Zheng58 were similar in community composition at genus level,but there were some differences at the species level.NMDS and cluster analysis at the level of OTU showed that BADH transgenic maize had no significant effect on the community structure of rhizosphere arbuscular mycorrhizal fungi.