Resistance to Neonectria ditissima in apple: insights from metabolomics and lipidomics analyses

European canker, caused by the necrotrophic fungus Neonectria ditissima, is the most serious disease in apple production in Sweden. The disease is favored by a relatively cool and rainy climate. The canker damages have a significant economic impact due to reduced bearing surface and increased orchard management costs. The possibilities for chemical and biological control are very limited. Therefore, directed breeding for new resistant cultivars is urgently needed. Knowledge of inheritance of canker resistance and understanding of molecular mechanisms involved in resistant and susceptible responses to fungal attacks would facilitate breeding. In this study, we evaluated the tempo-spatial differences in plant-pathogen interactions in a set of partially resistant and susceptible cultivars by conducting metabolomic and lipidomic analyses. The major trends in metabolomics and lipidomic profiles were common among cultivars, irrespective of the degree of susceptibility. Several metabolites and lipids varied with time point and cultivar under N. ditissima infection. Putative key metabolites such as suberic acid and jasmonic acid were upregulated in all cultivars upon infection. Additionally, several lipids exhibited changes 30 to 45 days post-inoculation. Thus, the approach used seems to have resulted in a rich data set to be further analyzed in light of ongoing QTL-mapping efforts.