USING FUNCTIONAL AND APPLIED GENOMICS TO IMPROVE STRESS AND DISEASE RESISTANCE IN FRUIT TREES
Location: Appalachian Fruit Research Laboratory: Innovative Fruit Production, Improvement and Protection
Title: Identification and mapping of genes differentially expressed during interaction of resistant and susceptible apple cultivars (Malus x domestica) with Erwinia amylovora
Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: January 4, 2008
Publication Date: June 1, 2008
Citation: Malnoy, M., Baldo, A.M., Borejsza-Wysocka, E., Norelli, J.L., Farrell, Jr., R.E., Bassett, C.L., Aldwinckle, H.S. 2008. Identification and mapping of genes differentially expressed during interaction of resistant and susceptible apple cultivars (Malus x domestica) with Erwinia amylovora. Acta Horticulturae. 793:195-199.
The necrogenic enterobacterium, Erwinia amylovora (Ea) is the causal agent of the fire blight (FB) disease of many Rosaceae species, including apple and pear. During the infection process, the bacteria induce an oxidative stress response with kinetics similar to those induced in an incompatible bacteria-plant interaction. In order to understand the mechanisms that distinguish resistant and susceptible responses in FB resistant and susceptible apple genotypes after inoculation with Ea, differentially expressed genes were identified by cDNA-AFLP analysis. cDNA was isolated from M.26 (susceptible) and Geneva.41 (G.41, resistant) apple tissues collected 2 and 48h after challenge with a virulent Ea strain or mock (buffer) inoculated. To identify differentially expressed transcripts, electrophoretic banding patterns were obtained from cDNAs treated using two cDNA-AFLP kits in order to maximize discovery of EST's associated with response to Ea. In the AFLP experiments, using both kits, M.26 and G.41, showed different patterns of expression, including genes specifically induced, not induced, or repressed by Ea. In total, 190 EST's differentially expressed between M.26 and G41 were identified and cloned using 42 pairs of AFLP primers. Blast analysis of the EST sequences identified three major classes of genes encoding proteins involved in perception, signaling, and defense. cDNA-AFLP analysis was successful in identifying ESTs differentially modulated in a resistant and a susceptible apple genotype in response to Ea. The time course of expression of some of these EST's is in the process of being analyzed, and selected EST's will be silenced in apple. This project is supported by a National Research Initiative Competitive Grant 2005-35300-15462 from the USDA Cooperative State Research, Education, and Extension Service.