[Expression and root exudation of Cry1Ab toxin protein in cry1Ab transgenic rice and its residue in rhizosphere soil].

The expression and root exudation of Cry1Ab toxin protein in cry1Ab transgenic rice (KMD) and its residue in rhizosphere soil were investigated. The results showed that content of Cry1Ab toxin protein in the shoot and root of KMD were 3.23-8.22 and 0.68-0.89 microg/g from early tillering to maturing stage, respectively. The content of the Cry1Ab toxin proteins via root exudation were 1.66-48.02 ng/(individual x d) at that phase. The results also demonstrated that the residue of the Cry1Ab toxin protein in rhizosphere soil was less than detectable level (0.5 ng/g air-dried soil). In addition, insecticidal bioassay indicated that rhizosphere soil and its extraction solution had no significant effect on mortality of first- and third-instar larvae of cotton bollworm (Heliochis armigera). It suggested that the KMD straws returned to the field might have the higher potential environmental risk than the root exudation.