The toxic effect of arachidonic acid and other unsaturated fatty acids on potato tuber cells

Abstract

It is well known that arachidonic acid can elicit the accumulation of terpenoid phytoalexins in potato tubers. Other unsaturated fatty acids, such as linoleic and linolenic acid, do not elicit the accumulation of potato phytoalexins. However, both linoleic acid and arachidonic acid were found to elicit a hypersensitive-like response in protoplasts similar to that elicited by cell wall components from the fungus Phytophthora infestans. We continued our investigations to determine whether unsaturated fatty acids elicit hypersensitive cell death in potato tuber tissue. It was found that unsaturated fatty acids were toxic to tuber cells. Linoleic acid and arachidonic acid were able to elicit significant cell death, whereas the esterified forms of arachidonic acid did not. Salycyl hydroxamic acid, which significantly blocked phytoalexin accumulation, did not block the cell death elicited by arachidonic acid. The data indicate that the toxic effect of arachidonic acid on potato tuber cells is unrelated to its ability to induce phytoalexin accumulation. The findings also indicate that protoplasts may still be useful in this host-pathogen interaction since both potato tuber cells and protoplasts react similarly to elicitor treatments.