Effects of Jasmonic Acid application to belowground part on the content of defence chemicals and activity of defence enzymes in Bt corn (Zea mays L.) seedlings

Bt (Bacillus thuringiensis) corn is one of the most rapidly commercialized anti-insect transgenic crops around the world. In the present study, we tested the Bt protein content, defense chemicals contents and defense enzymes activities in both leaves and roots of Bt corn varieties 5422Bt1 and 5422CBCL, as well as their conventional corn 5422 seedlings with two fully expanded leaves, which had been treated with 1.0 µM jasmonic acid (JA) to the belowground part for 24 h. The result showed that JA treatment to the belowground part could significantly increase the peroxidase activity in the roots of conventional corn 5422, the polyphenol oxidase and peroxidase activities in the roots of Bt corn 5422Bt1 and the Bt protein content and peroxidase activity in the roots of Bt corn 5422CBCL. Meanwhile, the DIMBOA content, polyphenol oxidase, peroxidase and catalase activities in the leaves of conventional corn 5422, the Bt protein content, polyphenol oxidase, peroxidase and catalase activities in the leaves of Bt corn 5422Bt1 and the polyphenol oxidase and peroxidase activities in the leaves of Bt corn 5422CBCL were systematically increased after JA was applied to the belowground part. These findings suggest that Bt gene introduction affects the induced defense effects of JA treatment to the belowground part of corn, leading to a stronger defense response in the root of Bt corns than the conventional corn. Systematic defense response is weak in the leaf of Bt corn 5422CBCL as compared to the conventional corn, while the systematic defense response in the leaf of Bt corn 5422Bt1 is similar to conventional corn 5422