Effects Of Bt Corn And Straw Returning On The Composition Of Arbuscular Mycorrhizal Community

Bt corn is one of the large-scale commercialized transgenic crops around the world,and its effect on the non-target organisms in soil is the key issues in the ecological risk assessment.AMF is a kind of obligate living beneficial microbes widely distributed in soil ecosystem,established mutually beneficial symbiosis with corn and closely related to corn nutrition as well as yield.In the present study,we stud ied the effect and mechanism of Bt corn cultivar 5422Bt1,5422 CBC L and non transgenic isogenic line 5422 planting and returning straw on the AMF community structure and function by tested the colonisation of AMF,the diversity of community structure composition as well as the expression of functional genesin greenhouse planting and pot experiment.1.After continuously five time planting Bt corn 5422Bt1,5422 CBC L and conventional corn 5422 of returning straw,the AMFcolonisation of corn root was measured by usingtrypan blue stain methodand sequenced by Illuminaplatform Miseqtechnologies,the results are as follows: the AMFcolonisation of Bt corn 5422Bt1 and 5422 CBC L significantly high than that of conventional corn 5422 during the fifth mature period in root;the AMFcolonisation of conventional corn has no significant difference during seedling stage in root after three corn cultivars subsequent.The diversity and richness of AMF community of three corn cultivars have no significant difference during the fifth mature period andsubsequent seedling stage in root and rhizosphere soil,the species composition of AMF has no significant difference,the main species were Glomus,Paraglomus and Glomeromycetes unclassified,Glomus is the dominant population.The percentage of the same OTU and different OTU which in the three corn cultivarsroots is 5.26% and 94.74% during the fifth mature period;while the percentage of the same OTU and different OTU which in the three corn cultivars rhizosphere soil is 15% and 85%.The percentage of the same OTU and different O TU which in the three cultivars roots of subsequent corns is 4.3% and 95.74% during the subsequent seedling stage;while the percentage of the same OTU and different OTU which in the three corn cultivars rhizosphere soil is13.33% and 86.67%.The AMF community structure of three corn cultivars have no significant difference during the fifth mature period andsubsequent seedling stage in root and rhizosphere soil.The Bt protein content,soil p H and organic carbon content significantly affected the AMF community structure in soil and root during the fifth mature period.The Bt protein content and total nitrogen content significant ly affectedthe AMF community struture in soil and root during subsequent seedling stage too.There has high similarity in AMF evolution in root and rhizosphere soil of Bt corn and conventional corn as well as conventional cornsubsequent.2.In pot experimen,we studied the difference of AMFcolonisation among the three corn cultivars by inoculating F.mosseae after 50 d and 80 d,and checked the expression of Phosphorus transport genes and function genes of corn root in 50 d by qPC R.The results are as follows: the AMFcolonisation of Bt corn 5422Bt1 and 5422 CBC L were significantly high than that of conventional corn 5422 in root at two sample time;the expression of Phosphorus transport genes and function genes of three corn cultivars have no significant difference in root betweet the treatment of inoculating F.mosseae(+G)and non-inoculating F.mosseae(-G)at 50 d.In conclusion,the Bt protein content significantly affected the AMF community structure in soil and rhizosphere root during the fifth mature period and subsequent seedling stage,while the Bt gene insertionhave no significantly affectedthe expression of Phosphorus transport genes and function genesof corn.