ARS | Publication request: Maize defense response against the european corn borer (Ostrinia nubilaslis): a losing battle?

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 7, 2011
Publication Date: N/A

Technical Abstract: The goal of this research is to understand how maize stems respond to European corn borer (ECB) damage and how these defense tactics affect the invading ECB. We measured the levels of the plant hormones, jasmonic acid (JA) and ethylene, as well as the transcript levels of their key biosynthetic enzymes, allene oxide synthase and 1-aminocyclopropane-1-carboxylate oxidase, respectively. The transcript levels of these enzymes and the quantity of both hormones were rapidly and strongly induced by ECB feeding suggesting an important role in regulating the defense response in maize stems. In addition to early signaling events, we also measured the quantities of downstream defenses such as benzoxazinoids, the kauralexin class of diterpene phytoalexins, and defensive proteins such as WIP1, a Bowman-Birk protease inhibitor. All of these maize defense metabolites are significantly upregulated as early as 24 hours after the initiation of ECB feeding. Even though maize actively mounts a defense response to ECB stem feeding, we did not observe any differences in percent weight gain between ECB fed on non-wounded control tissues as compared to 24 hr ECB damaged tissues. The defense response in maize stems does not appear to negatively impact ECB growth suggesting that ECB have adapted to maize defenses. We are currently in the process of trying to understand how ECB thrive in the presence of these defensive compounds in the context of a relatively nutrient poor diet.