[Effect of methyl jasmonate on aphid resistance of chrysanthemum.]

We examined the effects of methyl jasmonate on aphid resistance of Chrysanthemum 'Hangbai'. Leaves of chrysanthemum cuttings were sprayed by methyl jasmonic with different concentrations (0.01, 0.05, 0.1, 0.5 and 1 mmol·L^-1) and then inoculated with the aphids Macrosiphoniella sanborni. The following parameters are measured, including protective enzymes activities, defense enzyme activities, osmotic substances, secondary metabolites, and key genes of the jasmonic signaling pathway. The relationship between aphid resistance and the jasmonic signaling pathway in chrysanthemum was probed. The results showed that, under the treatments of all the five concentrations of methyl jasmonic, the activities of leaf protective enzymes and defense enzymes as well as the contents of secondary metabolite were increased in Chrysanthemum, whereas the contents of malondialdehyde and soluble sugar were reduced. Moreover, exogenous methyl jasmonate treatment induced the expression of CmAOS and CmCOI1, enhanced the content of endogenous jasmonic acid and the aphid resistance of chrysanthemum.