Diversity and ecological significance of fungal endophyte natural products

Endophytic fungi are usually defined as nonpathogenic fungal symbionts. The plant-fungus relationship can be classified as mutualistic when both partners acquire a fitness benefit from the other, with a special regard to competitors. In this case, it is supposed that fungal metabolites play an important role, as demonstrated by numerous biological activities affecting the ecosystem community. For example, fungal secondary metabolites may be antimicrobial (against microbe competitors and plant pathogens), toxic against insects or vertebrate herbivores, or even phytotoxic. In this chapter, we review the fungal endophyte natural products with regard of their ecological significance, while showing their important chemical diversity as a result of biosynthetic combinations. Articles lacking the ecological dimension have been excluded. We mainly focus, but not exclusively, on the bibliography of the past 6 years, gathering nearly 140 molecules and more than 260 references.