The Coumarins: Secondary Metabolites Playing a Primary Role in Plant Nutrition and Health

Although abundant in soils, iron (Fe) is poorly bioavailable for plants. Improving Fe uptake in crops, enabling them to grow in Fe-depleted soils, has become a major focal interest. The secretion of Fe-mobilizing coumarins by plant roots recently emerged as an important factor allowing nongrass species to cope with low Fe bioavailability. The main molecular actors involved in the biosynthesis and secretion of coumarins have been identified, but the precise regulatory mechanisms that tune their production remain poorly understood. Here, we review the recent progress in coumarin synthesis and transport in plants and future research directions to gain knowledge of these mechanisms, which will offer novel opportunities for improving plant growth and health and for generating Fe-fortified crops.

Automated summary

The secretion of Fe-mobilizing coumarins by plant roots is a key factor enabling plants to grow in Fe-depleted soils. While the main molecular actors involved in the biosynthesis and secretion of coumarins have been identified, the precise regulatory mechanisms that tune their production remain poorly understood.