Stop and smell the fungi: Fungal volatile metabolites are overlooked signals involved in fungal interaction with plants

• Some fungal volatile metabolites function as intra- or inter-organismal signals.
• Fungal volatile metabolites affect plant growth, development and/or health.
• Information about how fungal volatile metabolites affect plants is limited.
• Research on the chemical ecology underpinning plant-fungal interactions is needed.

Diverse fungi are intimately associated with plants, and molecules secreted from both the plant and fungal sides play critical roles in the establishment of their associations and affect plant growth and health. Through evolutionary arms races or strategic alliances with plants, fungi and other microbes have invented a bewildering array of secreted molecules to parasitize or communicate with plants. Research empowered by omics data and tools has greatly advanced understanding of the nature, role and mechanism of action of many secreted fungal proteins that affect plants directly or indirectly. However, available information about fungal volatile metabolites with similar functions is quite limited. Through this review, we aim to stimulate expeditions to this vastly under-explored frontier of fungal chemical ecology.