Biological control of postharvest diseases by microbial antagonists: how many mechanisms of action?

The postharvest phase has been considered an environment for successful application of biological control agents (BCAs). However, the interactions between fungal pathogen, host (fruit), and antagonist are influenced by several parameters such as temperature, oxidative stresses, oxygen composition and water activity that could determine the success of biocontrol. Knowledge of the modes of action of BCAs is essential in order to enhance their viability and increase their potential in disease control. The antagonists display a wide range of modes of action: antibiosis, competition for nutrients and space, parasitism and induction of resistance are considered the main ones. Their efficacy, however, is related to the host and the pathogen; sometimes, these mechanisms could act simultaneously, and it is therefore difficult to establish which is related to a specific antifungal action. The current review presents a brief summary of the research that has led to a better understanding of the mode of action of BCAs with particular emphasis on the most recent literature.