Allelopathy Journal

We determined the changes in content of direct defence chemicals and expression of defence-related genes in non-treated parts (second leaf and root) after the first leaf of corn seedlings was damaged by Asian corn borer (Ostrinia furnacalis) to examine whether gene introduction would alter the systematic induced effects of pest damage on corn. The Bt protein content in the second leaf and root of Bt corn 5422Bt1 could not be increased by pest damage, whereas the content of Bt protein in the root of Bt corn 5422CBCL could be systematically increased by pest damage compared to healthy plants. Gene expression of PAL, MPI, PR-2a and TPS in the second leaf of two Bt corns could be systematically induced by pest damage, whereas, only gene expression of MPI and PR-2a in the second leaf of conventional corn 5422 could be systematically induced by pest damage. Besides, the pest damage induced the gene expression of Bx6, Bx9, PAL, MPI, PR-2a, FPS and TPS in the root of conventional corn 5422, gene expression of Bx6, Bx9, PAL, PR-2a and TPS in the root of Bt corn 5422CBCL and gene expression of Bx9, PAL and TPS in the root of Bt corn 5422Bt1. These findings suggest that Bt gene introduction alters the systematic induced effects of pest damage on the corn, leading to a stronger chemical defence response in the second leaf for Bt corns than in conventional corn. However, systematic induced chemical defence response was weak in the roots for Bt corns than their conventional corn, which implies a synergetic relationship between the Bt gene introduction and chemical defence response in leaf, while, there was a antagonistic relationship in the root.