Effect of Bt gene insertion on growth, physiology and gene expression of phosphorus transporter gene of corn after arbuscular mycorrhizal fungi colonization

Bt (Bacillus thuringiensis)-corn root can exudate insecticide active Bt protein and persistent toxin in soils which can affect symbiotic relationship between corn and arbuscular mycorrhizal fungi (AMF). In this paper, two Bt-corn varieties '5422Bt1' (Bt11) and '5422CBCL' (Mon810), and one conventional corn variety '5422' were used to explore the difference between Bt and non-Bt varieties with Funneliformis mosseae inoculation and non-inoculation treatments. The colonization of AMF, phosphorus transporter gene expression, growth and nutrients contents were measured after 50 d and 80 d of inoculation. The results showed that AMF colonization of Bt-corn varieties '5422Bt1' and '5422CBCL' were significantly higher than that of the conventional variety '5422' at 50 d and 80 d after treatment, which increased by 13.54% and 11.24% at 50 d and then by 9.83% and 6.70% at 80 d, respectively. There was no significant difference in phosphorus transporter gene expression between inoculation and non-inoculation for Bt-corn varieties at 50 d. The height of '5422' under inoculation treatment was significantly higher than that of '5422Bt1' and '5422CBCL' at 50 d. Dry weight of '5422Bt1' under inoculation treatment was significantly higher than that of '5422CBCL' at 50 d. The root length, root surface and root volume of '5422Bt1' were significantly higher than those of '5422' and '5422CBCL' under non-inoculation treatments at 80 d. Bt gene insertion affected nitrogen concentration of the two Bt-corn varieties ('5422Bt1'and '5422CBCL') at the two sampling times. As compared with conventional corn variety, the two Bt-corn varieties needed more nitrogen and phosphorus to synthetize Bt protein. There were significant differences among the responses of three corn varieties to AMF inoculation. F. mosseae inoculation significantly increased nitrogen absorption of'5422Bt1' and '5422CBCL' at the two sampling times (50 d and 80 d). In conclusion, the effect of Bt-gene insertion and AMF inoculation on growth and nutrient utilization of Bt-corn was mainly dependent on its transformation event.