Study On The Role Of JA Signaling Pathway In Nilaparvata Lugens-induced Rice Defense Responses

Based on previous research works in a model system consisting of rice, the rice brown planthopper Nilaparvata lugens (Stal) and its egg parasitoid Anagrus nilaparvatae Pang et Wang, the role of jasmonates (JA) signaling pathway in N. lugens-induced rice defense responses was studied. The results are as follows:1) The parasitoid was obviously attracted by the volatiles emitted from plants that were wounded and treated with JA (21.03-126.18 ug plant-1). Using solid phase microextraction (SPME), more than 20 components have been collected from the headspace of plants, and 14 main components were identified by GC-MS, which include 2 terpenoids, 2 ketones, 1 aldehyde, 1 aliphatic unsaturated hydrocarbons and 8 aliphatic saturated hydrocarbons. JA elicitation dramatically increased the release of (E)-2-Hexenal, D-limonene (both of which were not detectable before elicitation), linalool, n-heptadecane and the total amount of the volatiles.2) There was no significant difference in the attractiveness to the parasitoid between the volatiles emitted from JA-treated plants and N. lugens-damaged plants, probably due to similar total amount of (E)-2-hexenal, linalool and n-octadecane, which were active components to attract the parasitoid, between the two treatments. Compared to N. lugens-damaged plants, JA elicitation resulted in (E)-2-hexenal, 2,6,6-trimethyl-l-cyclohexene-l-carboxaldehyde (both of which were not detectable in N. lugens-damaged plants), n-pentadecane and n-heptadecane increase, while other components and the total volatiles amount showed on difference3) JA elicitation showed no effect on the feeding, survival rates and fecundity of N. Lugens, and its influence on the host selection behavior of N. lugens was onlyfound 1h after the release of the insect.4) No significant difference was found in endogenous JA concentrations between the N.lugens-damaged plants and non-manipulated plants during 0-24 h after the start of the herbivore feeding.The results stated as above suggested a little role of the JA signaling pathway in the N. lugens-induced rice defense responses. Possible signaling pathways that were simultaneously elicited by exogenous application of JA and N. lugens damage might explain the differences and similarities in the volatiles profiles between these two treatments.