Insights into Fruit Defense Mechanisms Against the Main Postharvest Pathogens of Apples and Oranges

Penicillium digitatum and P. expansum are the most devastating pathogens of citrus and pome fruits respectively, causing significant economic losses during postharvest handling worldwide. To obtain new rational and environmentally friendly control alternatives, a better understanding of the fruit-pathogen interaction may be considered as a novel perspective for the control of postharvest diseases. The main objective of our studies was to gain insights into the fruit-pathogen interactions, specifically in oranges and apples defence responses against compatible and non-host pathogens. For such purposes, firstly a deep study of infection capacities of both pathogens in oranges and apples at different conditions was performed. Later, we characterized the effect of wound response in oranges and apples harvested at different maturity stages and temperatures, as well as we identified the possible compounds involved in the wound healing process. In addition, a visualization of lignin, suberin and callose in apple and oranges tissue was conducted using histochemical tests. Finally, in apples, a transcriptomic study in response to compatible and non-host pathogen was conducted; and the expression of several genes involved in the phenylpropanoid pathway were quantified in citrus fruit.