Fusicoccins are organic compounds produced by a fungus.

Fusicoccins are diterpenoid glycosides produced by the fungus Fusicoccum amygdali,[1] which is a parasite of mainly almond and peach trees.

Fusicoccin was and is extensively used in research regarding the plant hormone auxin and its mechanisms.

Fusicoccin is a member of a diterpenoid class which shares a 5-8-5 ring structure and is called fusicoccane.

[2] In fungi, fusicoccin is biosynthesized via Phomopsis amygdali fusicoccadiene synthase (PaFS) from universal C5 isoprene units dimethylallyl diphosphate (DMAPP) and isopentenyl diphosphate (IPP).