ARS | Publication request: Identification of genes expressed in apple (Malus x domestica) in response to Erwinia amylovora infection

Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: November 15, 2006
Publication Date: January 13, 2007
Citation: Farrell, Jr., R.E., Bassett, C.L., Norelli, J.L., Baldo, A.M., Aldwinckle, H., Wisniewski, M.E. 2007. Identification of genes expressed in apple (Malus x domestica) in response to Erwinia amylovora infection [abstract]. Plant and Animal Genome Conference. p. 218.

Technical Abstract: Host-pathogen interactions are critical in determining successful infection by the pathogen or the ability to resist infection by the host. Understanding the steps that define this interaction will aid the development of strategies to increase host disease resistance. To identify host genes that respond to pathogen infection, we have chosen to analyze the response of young apple leaves to Erwinia amylovora during the development of fire blight, a disease causing significant losses in apple orchard production. Suppression subtractive hybridization is a powerful method for the systematic global analysis of both up- and down-regulated genes, and was applied to study the temporal progression of fire blight using a susceptible cultivar, 'Gala'. In this study, sampling occurred at defined intervals from the start of infection. In the early hours, post-infection (1h, 2h, and 24h) host genes associated with photosynthesis and signaling, as well as a few host defense-related genes, were down-regulated. Some pathogen responsive (PR) genes were up-regulated late (48h and 72h) post-infection, including chitinase and Mal d1. A second study analyzed differences in response to E. amylovora between a resistant (Geneva 41) and susceptible (M.26) host cultivar. Although there were few differences detected between the two cultivars, several genes were observed to be uniquely up- or down-regulated. For example, a Cytochrome b6 was differentially regulated in the susceptible and resistant cultivar.