Elicitation of phytoalexins by arachidonic and eicosapentaenoic acids: a host survey

Accumulation of the sesquiterpenoid phytoalexins rishitin and lubimin in potato tubers is elicited by the polyunsaturated fatty acids all-cis-5,8,11,14-eicosatetraenoic acid (arachidonic) and all-cis-5,8,11,14,17-eicosapentaenoic acid, which are present in the fungus Phytophthora infestans. The ability of these acids to elicit the accumulation of phytoalexins in members of the Convolvulaceae (sweet potato), Leguminosae (broadbean, French bean, pea, soybean), Solanaceae (pepper, potato, tobacco, tomato) and Umbelliferae (carrot, parsnip) was investigated. The acids elicited accumulation of rishitin and lubumin in potato, as previously reported, and the sesquiterpene capsidiol in pepper fruit. The acids did not elicit phytoalexin accumulation in the other hosts tested.