Analysis of fatty acids in lipids of Verticillium dahliae and induction of lubimin accumulation in eggplant

The unsaturated fatty acid pattern and content of the main lipid fractions of three isolates of Verticillium dahliae were investigated, Oleic (C_18:1), linoleic (C_18:2) and linolenic (C_18:3) acids were the unsaturated fatty acids detected in the polar lipids and in the free fatty acids extracted from myceha of three isolates of the fungus. The concentration of the three fatty acids in polar lipids was about double that in free fatty acids, Linoleic acid was the predominant fatty acid in both lipid fractions. The capacity of linoleic and linolenic acids to induce lubimin accumulation in eggplant fruit discs was evaluated in comparison with that of the polyunsaturated fatty acid arachidonic acid, which is a known elicitor of phytoalexin synthesis in potato tuber. The accumulation of moderate levels of the phytoalexin was induced by arachidonic and linolenic acids, A higher induction was observed when browning of the tissue was inhibited by phenylthiourea. Under these conditions, linoleic acid induced only a slight accumulation of lubimin. The possible role of linolenic acid in triggering defence reactions in eggplant is discussed.