Are differentially expressed genes associated with contents of some chemical compounds in apple fruit challenged with Penicillium expansum?

Fruit decay occurring during cold storage of apple fruit, e.g., blue mold caused by Penicillium expansum, is a major problem in apple production, especially in organic cultivation and other production systems that do not allow post-harvest anti-fungal treatments. Fruits of susceptible and resistant apple cultivars were challenged with Penicillium expansum spores, and samples of inoculated and control fruits were taken in time series. Differentially expressed genes were identified using an AryANE chip containing 60K apple transcripts. Differentially expressed genes were then analysed for blast similarity, gene ontology and pathway analysis. In another study we quantified some selected chemicals in both inoculated and control fruits, e.g, total polyphenols, individual polyphenolic compounds, total organic acids as well as individual acids to study the possible association of these chemical compounds with the level of fungal resistance. The results of the gene expression study together with the results of the chemical evaluation will enable us to find candidate genes that can be used in breeding programs for development of apple cultivars with improved resistance to storage diseases.