Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 6, 2005
Publication Date: January 1, 2006
Citation: Harfouche, A.L., Shivaji, R., Stocker, R., Williams, W.P., Luthe, D.S. 2006. Ethylene signaling mediates a maize defense response to insect herbivory. Molecular Plant-Microbe Interactions. 19:189-199. Interpretive Summary: Fall armyworm and southwestern corn borer are major insect pests of corn in the southern United States. Feeding by these insects on leaves of young corn plants reduces yield and quality of grain. The development and release of corn germplasm lines with genetic resistance to these pests provided an environmentally sound and cost effective way to reduce losses to these insects. Fall armyworm or southwestern corn borer larvae that feed on leaves of resistant plants are smaller than those that feed on susceptible plants. A unique protein, a cysteine protease, that accumulates at the sites where larvae feed on leaves within the plant whorls has been identified. In a series of experiments, the effects of blocking ethylene synthesis in a resistant, Mp708, and a susceptible, Tx601, inbred line of corn were investigated. When fall armyworm larvae were fed on leaves of resistant plants after ethylene synthesis was blocked, the larvae grew larger than when ethylene synthesis was not blocked. Blocking ethylene synthesis in the susceptible corn inbred did not affect larval growth. Blocking ethylene synthesis reduced, but did not completely inhibit, the synthesis of the unique cysteine protease in the resistant line. Ethylene is a component of a pathway leading to resistance of the inbred line, Mp708. These results give additional evidence that the cysteine protein found in Mp708 is important to resistance and that transferring the gene responsible for its production into susceptible corn genotypes lacking the gene should increase resistance to fall armyworm and reduce losses to the insect.