Volatile organic compounds: from figurants to leading actors in fungal symbiosis.

Symbiosis involving two (or more) prokaryotic and/or eukaryotic partners is extremely widespread in nature, and it has performed, and is still performing, a key role in the evolution of several biological systems. The interaction between symbiotic partners is based on the emission and perception of a plethora of molecules, including volatile organic compounds (VOCs), synthesized by both prokaryotic and eukaryotic (micro)organisms. VOCs acquire increasing importance since they spread above and below ground and act as infochemicals regulating a very complex network. In this work we review what is known about the VOCs synthesized by fungi prior to and during the interaction(s) with their partners (either prokaryotic or eukaryotic) and their possible role(s) in establishing and maintaining the symbiosis. Lastly, we also describe the potential applications of fungal VOCs from different biotechnological perspectives, including medicinal, pharmaceutical and agronomical.