Inhibition of steroid glycoalkaloid accumulation by arachidonic and eicosapentaenoic acids in potato.

Eicosapentaenoic and arachidonic acids extracted from the fungus Phytophthora infestans elicit the accumulation of fungitoxic sesquiterpenoid stress metabolites and inhibit the accumulation of steroid glycoalkaloids in potato tubers. This dual activity, which did not occur with other saturated and unsaturated fatty acids tested, corresponds to the activity of incompatible races of Phytophthora infestans and crude elicitor preparations from Phytophthora infestans that contain bound forms eicosapentaenoic and arachidonic acids. Arachidonic acid applied to potato slices, which had been aged for various time intervals, elicited the accumulation of sesquiterpenoid stress metabolites and concomitantly inhibited the accumulation of steroid glycoalkaloids.