|FARRELL, ROBERT - PENNSYLVANIA STATE UNIVERSITY|
|ALDWINCKLE, HERBERT - CORNELL UNIVERSITY|
|MALNOY, MICKAEL - IASMA RESEARCH CENTER|
Submitted to: BMC Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2009
Publication Date: 1/4/2010
Citation: Baldo, A.M., Norelli, J.L., Farrell, R., Bassett, C.L., Aldwinckle, H., Malnoy, M. 2010. Identification of genes differentially expressed during interaction of resistant and susceptible apple cultivars (Malus x domestica) with Erwinia amylovora. Biomed Central (BMC) Plant Biology.
Interpretive Summary: The bacterium Erwinia amylovora causes fire blight (FB) disease in many Rosaceae crops. During infection the bacteria cause an oxidative stress response similar to those induced in an incompatible bacteria-plant interaction. Although a resistance mechanism to E. amylovora in host plants has not yet been characterized, recent work has identified some cellular events which occur in resistant and/or susceptible host interaction with E. amylovora: In order to understand host responses to FB, differentially expressed genes were identified by cDNA-AFLP analysis in resistant and susceptible apple genotypes after inoculation with E. amylovora. cDNA were isolated from M.26 (susceptible) and G.41 (resistant) apple tissues collected 2h and 48h after challenge with a virulent E. amylovora strain or mock (buffer) inoculation. Differentially expressed transcripts were identified by electrophoretic banding patterns obtained from cDNAs. In AFLP experiments, M.26 and G.41 showed different patterns of expression, including genes induced, not induced, or repressed by E. amylovora. In total, 190 ESTs differentially expressed between M.26 and G.41 were identified using 42 pairs of primers. Analysis of global EST expression in a resistant and a susceptible apple genotype identified different major classes of genes. EST sequencing data showed that genes linked to resistance, encoding proteins involved in perception, signaling, defense and apoptosis, were modulated by /E. amylovora/ in the host. The expression time course of some of ESTs selected via a bioinformatic analysis has been characterized. These results are being used to develop hypotheses of resistance or susceptibility in /Malus /to /E. amylovora/ and an initial categorization of genes involved in recognition events, early signaling responses and the subsequent development of resistance or susceptibility/./ These data also provide potential candidates for improving apple resistance to fire blight either by marker-assisted selection or genetic engineering.
Technical Abstract: The necrogenic enterobacterium, Erwinia amylovora is the causal agent of the fire blight (FB) disease in 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. No resistance mechanism to E. amylovora in host plants has yet been characterized, recent work has identified some molecular events which occur in resistant and/or susceptible host interaction with E. amylovora: In order to understand the mechanisms that characterize responses to FB, differentially expressed genes were identified by cDNA-AFLP analysis in resistant and susceptible apple genotypes after inoculation with E. amylovora.