ABSTRACT
Pathogens that penetrate into unripe fruits are exposed to the hostile environment found within the host. During ripening, fruits undergo physiological changes, such as activation of ethylene biosynthesis, cuticular changes, cell-wall loosening, and a decline of antifungal compounds, which release the fungus from its quiescent state and promote a necrotrophic and pathogenic life style. The plant perception of fungal molecules early in the plant–pathogen encounter may activate a differential complex network of processes in mature and unripe fruit that leads to the activation of postharvest pathogens in ripening fruits. These processes activated by postharvest pathogens have the ability to affect the host environment by enhancing fruit ripening and/or modulating ambient pH levels to control the transition from quiescent to active infection. The necrotrophic stage becomes active as the fruit ripens and the fungal pathogen switches to active secretion of effectors and pathogenicity factors. Understanding regulation of quiescent, necrotrophic, and pathogenic stages should lead to new approaches for disease control.
