|Norelli, John (jay)|
|Farrell, JR., Robert - PENN STATE UNIVERSITY|
|Aldwinckle, Herb - CORNELL UNIVERSITY|
Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: January 4, 2008
Publication Date: June 1, 2008
Citation: Norelli, J.L., Farrell, Jr., R.E., Bassett, C.L., Baldo, A.M., Lalli, D., Aldwinckle, H.S., Wisniewski, M.E. 2008. Rapid transcriptional response of Malus to Erwinia amylovora infection. Acta Horticulturae. 793: 189-194. Technical Abstract: Suppression subtractive cDNA hybridization (SSH) was used to identify genes that are differentially up- and down-regulated in apple (Malus X domestica) in response to challenge with Erwinia amylovora (Ea). cDNA libraries were constructed from Ea- and mock-challenged 'Gale Gala' apple leaf tissue at various time intervals after challenge treatment, ranging from 1 to 72 hours post inoculation (hpi), and utilized in SSH. A total of 432 non-redundant Malus ESTs isolated by SSH in response to Ea challenge were characterized by bioinformatic analysis. Many ESTs identified following Ea-challenge of apple were similar to genes previously reported to respond to bacterial challenge in Arabidopsis thaliana. The results indicate that there was a substantial early (1 and 2 hpi) transcriptional response in apple to fire blight disease involving both the down- and up-regulation of host genes. Additionally, genes identified responding to fire blight challenge early (1 and 2 hpi) differed from those identified later (24, 48, 72 hpi) in the infection process. For example, within the defense/stress functional category, ESTs representing several different PR proteins were first detected 48 hpi (up-regulated), whereas, earlier defense/stress ESTs were primarily associated with oxidative and osmotic stress. Gene silencing is being used to elucidate the role of specific candidate ESTs in resistance and susceptibility. This project is supported by a National Research Initiative Competitive Grant 2005-35300-15462 from the USDA Cooperative State Research, Education, and Extension Service and a grant from NutriCore, N. E.