Study On The Effect Of Transgenic Maize With Cry1le Gene On Rhizosphere Microbial Community Structure And Fertility

In recent years, it is worthwhile to study the effect of transgenic maize on the environment especially on non-target organisms in the soil due to the popularization and application of these species. In this study, the transgenic maize IE09S034 which producing Cry1 Ie toxins, and its parental non-transgenic maize were planted in field conditions for two years in 2012 and 2013. Soil microbial community structure were analyzed by PCR-DGGE and PLFA at pre-seeding stage, jointing stage, silking stage and mature stage. In addition, soil enzyme activity and soil chemical properties were also analyzed. The main results are as follows:1. The results of DGGE test showed that bacterial community structure is relatively stable in rhizosphere soil. There was no significant difference between the effect of transgenic cry1 Ie maize IE09S034 and that of non-Bt maize on bacterial community structure in rhizosphere soil during the same growth period. The similarity of bacterial community structure in rhizosphere reached a high level in four growth stages of maize in 2012 and 2013; PLFA analysis showed that there is no significant difference between the bacterial microorganism biomass of transgenic cry1 Ie maize IE09S034 and that of non-Bt maize in growth stages of maize in soil except the jointing stage in 2012. In addition no significant difference of soil bacterial microorganism biomass and G+/Gbacterial biomass was found in four growth stages of maize. The ratio of G+/G- bacteria biomass in four growth stages were all more than 1. In 2013 there was no significant difference between microorganism biomass, bacterial amount and ratio of G+/Gbacteria of transgenic cry1 Ie maize IE09S034 and those of non-Bt maize in whole growth stages. And these results were accordance with those of DGGE.2. Results of soil chemical properties analysis showed that, the p H value, soil moisture, organic content, available potassium content and the available phosphorus content in soil between two kinds of maize were not significantly different in the whole maize growth periods except that of alkali-nitrogen in the jointing stage and the mature stage in 2012. In the year of 2013, the soil moisture and soil organic content between two kinds of maize were significantly different in the silking stage.However the p H value, the content of available potassium and available phosphorus were not significantly different in the whole growth periods between the two treatments. And the alkali-nitrogen content did not show significant difference in silking stage in 2013. According to the two-years-test the difference will appear in some periods, but did not maintain in the same period. In summary, the cry1 Ie gene transgenic maize IE09S034 was not impact on soil chemical properties.3. According to the selected index of soil enzymes, the effects of transgenic maize and its parental non transgenic maize on soil enzymes were investgated during different growth periods. Within the two consecutive years, 2012 and 2013, the transgenic maize had no significant influence on the activities of soil invertase, acid phosphatase and alkaline phosphatase. The activities of soil urease did not appear significant difference between transgenic maize and non transgenic maize in the whole growth periods in 2012. However in the silking stage of 2013, the soil urease activity of transgenic maize was significantly different from that of non transgenic maize.