Rapid transcriptional response of apple to fire blight disease revealed by cDNA suppression subtractive hybridization analysis

Abstract

Fire blight, caused by the bacterium Erwinia amylovora, is a destructive disease of many tree and shrub species of the Rosaceae. 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 E. amylovora. cDNA libraries were constructed from E. amylovora-and mock-challenged apple leaf tissue at various time intervals after challenge treatment, ranging from 0.25 to 72 h postinoculation (hpi), and utilized in SSH. Gel electrophoresis of PCR-amplified SSH cDNAs indicated a greater quantity and size diversity in the down-regulated EST population at early times after challenge (1 and 2 hpi) compared to early up-regulated sequences and to sequences down-regulated at later (24 and 48 hpi) times after challenge. A total of 468 non-redundant Malus ESTs isolated by SSH in response to E. amylovora challenge were characterized by bioinformatic analysis. Many of ESTs identified following E. amylovora 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 (25, 48, and 72 hpi) in the infection process.

FIBRILLIN4Is Required for Plastoglobule Development and Stress Resistance in Apple and Arabidopsis

“…Quantitative real-time PCR analyses were performed at the Pennsylvania State University Genomics Core Facility as described previously (Jensen et al, 2010; for primers and probes, see Supplemental Table S2). For PR gene expression analyses, apple inoculations with Erwinia amylovora and tissue collection were done as described by Norelli et al (2009) using gene-specific primers for each PR gene (for primers, see Supplemental Table S2). Genomic DNA was isolated from young leaves using standard methods (Kasajima et al, 2004).…”

Identification of SNPs linked to eight apple disease resistance loci

“…NZsnEH034548 (Norelli et al 2009;Gardiner et al 2012; Table 2, Supplementary Table 2). Marker rp16k15, developed on one BAC 16k15 insert-end, and NZsnEH034548 were mapped by Fahrentrapp et al (2013) at 0.17 cM resp.…”

Fire Blight: Applied Genomic Insights of the Pathogen and Host

“…We know that E. amylovora induces lipid peroxidation, electrolyte leakage, and modulation in antioxidant status in its susceptible host, an effect that is more characteristic of the oxidative burst generally associated with the hypersensitive reaction in nonhosts than susceptible in a host (121). Adjacent host cells surrounding the infection site are associated with localized acquired resistance that involves cell wall reinforcement (i.e., callose deposition), accumulation of phytoalexins, and activation of three pathogenesis-related (PR) protein genes of apple, PR2, PR5, and PR8 (3, 7, 76,122). PR proteins can also be synthesized throughout the plant and lead to systemic acquired resistance (SAR), which represents the third line of defense mediated by SA (122).…”

“…Gardiner et al (33) identified several candidate resistance genes, including a class III peroxidase, a leucine-rich repeat protein, and a heat shock protein (HSP90) associated with the major fire blight QTL on linkage group 3. The HSP90 genes are interesting candidates because they were found to be differentially expressed in three separate studies of genes differentially regulated following inoculation of apple with E. amylovora (3,41,76) and were found associated with two of the three major fire blight QTLs. A complex of HSP90, SGT1, and RAR1 is known to be important in the regulation of NBS-LRR resistance proteins in planta and is essential for disease resistance triggered by a number of NBS-LRR resistance proteins, such as RPM1 (37).…”