Biosynthesis of phytoalexin in carrot root requires ethylene action

The role of ethylene in phytoalexin production by carrot ( Daucus carota L.) roots was investigated using the ethylene action inhibitor 1-methylcyclopropene (MCP). Exposure of carrot roots to ethylene, UV-B irradiation, inoculation with fungal pathogens, treatment with 2,4-D or methyl jasmonate induced accumulation of the phytoalexin 6-methoxymellin (6-ME). Exposure to MCP for 4–12 h prior to the treatments completely inhibited 6-ME accumulation, indicating that 6-ME synthesis by carrot roots requires ethylene action.