Coumarins: versatile secondary metabolites with diverse functions

Abstract

Abstract Coumarins are plant secondary metabolites that have been found to play a role in a variety of plant processes. These functions include improving plant defence, assisting in iron uptake in alkaline soils, and having the ability to reduce radical oxygen species (ROS), reducing the amount of plant oxidative stress. The functions in defence and iron uptake in particular have been well characterised. The ROS mitigation function of coumarins has also been intensively studied, albeit often not in plants. This creates opportunities for plant coumarin research, as parts of that research can be extrapolated to plants. Application of coumarin research could in the future lead to crops that are better adapted to the environment they are in, by employing coumarin-based strategies to increase plant defence, reduce iron deficiency-based stress, and reduce damage from ROS produced by various stress types. In this review, the three main functions of coumarins will be extensively discussed, as well as the interplay that the mechanisms behind these functions may have.