Endophytic fungi as potential inhibitory agents of downy mildews: A review and future prospects

Biotic stresses are responsible for important crop losses each year. Downy mildews (DMS), elicited by obligate pathogens of the oomycete Peronosporaceae family, are recognized as an increasing threat for crop production worldwide. These diseases are responsible for major food losses and also damage valuable natural ecosystems. Fungicides have been widely employed for managing DMS, but they can be harmful to non-target organisms, human health and soil functioning. For this reason, biological control is attractive as an alternative and ecofriendly approach to deal with plant diseases. Potential biocontrol agents include endophytic fungi (EF). Endophytes produce metabolites that can protect host plants against fungi and other pests including DMS. Endophytes work as biocontrol agents by inducing the lignification of cell walls and producing fungicides and other antimicrobial compounds. Research on EF in the leaves of the host plants is crucial to the search for biocontrol methods for managing DMS. Several factors limit the development of DMS as biocontrol agents. This review summarizes the published research on the use of fungal endophytes as biological agents to control DMS with a particular emphasis on their identification, modes of action, and efficacy.