Abstract:

To further clarify the mechanism of plant resistance to insects induced by methyl jasmonate (MeJA), the inducement of exogenous MeJA on activities of polyphenol oxidase (PPO), peroxidase (POD), lipoxygenase (LOX), and expression of genes encoding hydroperoxide lyase (HPL) and proteinase inhibitor (PI-I and PI-II) in tobacco leaves were studied. And the damaged area of leaves and weight of cotton bollworms were bioassayed. The results showed that after exogenous application of MeJA at a concentration of 100 μmol/L, the activities of PPO, POD and LOX increased significantly. Also, expression of HPL, PI-I and PI-II enhanced evidently. The damaged area of tobacco leaves treated with MeJA decreased apparently compared with that of control. The larvae after 72 h feeding on control plants were larger than that on plants treated with MeJA. Together, our findings indicated that MeJA plays critical roles in induced resistance to cotton bollworms in tobacco.