Dynamic changes in common metabolites and antioxidants during Penicillium expansum-apple fruit interactions

Penicillium expansum-infected apple fruit resulted in a disrupted balance of primary metabolites and impacted the ascorbate-glutathione cycle. The initial decline in fructose, malic acid, shikimic acid and total ascorbate content (6 hpi) was followed by a significant increase in malic acid (24 hpi) and total glutathione (3 dpi). Significant increase in sucrose was accompanied by a decline in glucose and ascorbate content (5 dpi). Total glutathione and shikimic acid gradually deteriorated with symptom development. A negative correlation was found between sucrose and ascorbate-glutathione pool. Other correlations were strong amongst other metabolites and lesion size indicating that they may be involved or important for apple fruit decay.