Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 10/4/2015
Publication Date: 10/11/2015
Citation: Zhu, Y., Mazzola, M., Fazio, G. 2015. Differential transcriptional regulation of defense-associated genes among apple rootstock genotypes in response to Pythium ultimum. American Phytopathological Society Annual Meeting. N/A.
Technical Abstract: Apple replant disease (ARD) poses a substantial threat to orchard establishment on replant sites. Deployment of resistant apple rootstocks is an ecologically desired, cost effective and durable disease control strategy particular for perennial production system. Candidate genes which function in pathogen recognition, hormone mediated defense activation and generation of antimicrobial metabolites were identified based on RNA-Seq based transcriptome profiling in response to Pythium ultimum infection. Regulation patterns of selected genes were examined among ARD tolerant (G41, G935) and susceptible (B9, M26) rootstocks. Expressed as a ratio of the quantified expression values in mock inoculated and P. ultimum infected roots, significant differences in expression patterns were observed between tolerant and susceptible varieties. Genes functioning in the biosynthesis of and signaling pathways regulated by the defense hormones ethylene and jasmonate (ACS, AOS, LOX1 and ERF) demonstrated either long-lasting activation, 3 days post-inoculation in G41, or the presence of a secondary peak at 14 dpi in G935, while the activation of these genes was transient in susceptible M26 and B9 rootstocks. Genes with annotated functions for production of antimicrobial secondary metabolites, such as those encoding beta-chitinase, chalcone synthase and biphenyl synthase, exhibited stronger and prolonged activation in tolerant G41 and G935, compared with susceptible M26 and B9 rootstocks.