Biosynthesis of phytoalexin in carrot root requires ethylene action

The role of ethylene in phytoalexin production by carrot (Daucus carota L.) roots mas investigated using the ethylene action inhibitor 1-methylcyclopr opene (MCP). Exposure of carrot roofs to ethylene, W-B irradiation, inocula tion with fungal pathogens, treatment with 2,4-D or methyl jasmonate induce d accumulation of the phytoalexin 6-methoxymellin (6-ME). Exposure to MCP f or 4-12 h prior to the treatments completely inhibited 6-ME accumulation, i ndicating that 6-ME synthesis by carrot roots requires ethylene action.