Isocoumarin, a phytoalexin implicated in development of resistance to carrot storage
pathogens (Mercier et al., 1993), is synthe-sized from acetyl CoA and malonyl CoA
through the polyketide pathway (Kurosaki and Nishi, 1988). Our results show that biosynthe-sis of ioscoumarin requires ethylene action. Treating carrots with MCP prior to exposureto ethylene eliminates accumulation of isocoumarin, although the mechanism of ac-tion is unclear. isocoumarin phytoalexin