Previously, we described a priming effect of α-linolenic acid (LnA) on anti-herbivore defense response in maize seedlings. 1 We showed that exogenous application of LnA stimulated higher jasmonic acid (JA) accumulation and herbivore-induced plant volatile (HIPV) emission after treatment with insect elicitor (IE). To further investigate the specificity of LnA's priming effect, we incubated maize seedlings in palmitoleic acid (PeicA), γ-linolenic acid (γ LnA) and stearic acid (StA) solutions, and analyzed HIPV emission in response to IE. Seedlings incubated in PeicA and γ LnA had 3 and 1.8 times higher HIPV release when compared to controls. In contrast, treatment with StA did not up-regulate HIPV release. We propose that the elevated level and/or the presence of unsaturated fatty acids sensitize the defense signaling system, which in turn augments the defense response of maize when under insect herbivore attack.
Keywords: Free fatty acid; green leaf volatiles; herbivore-induced plant volatiles; insect herbivory; priming.