Lipids of rust fungi. I. Lipid metabolism of germinating flax rust uredospores.

Abstract

Flax rust uredospores were germinated on demineralized water for 8 hours and the changes in total lipid and lipid content were determined at 2-hour intervals. The lipid extracts were fractionated by means of solvent extractions. The amounts of total lipid, non-saponifiable lipid, and lipid phosphorus were determined. Fatty acid compositions of the total lipids and free fatty acid fractions were determined by means of gas chromatography.The total lipid content did not decrease appreciably until after the fourth hour of germination; after 4 hours the rate of decline was more rapid. The non-saponifiable lipids and the lipid phosphorus increased gradually during the 8-hour germination period.During the first 2 hours of germination, about half of the cis-9,10-epoxyoctadecanoate in the glyceride form was hydrolyzed and converted to threo-9,10-dihydroxyoctadecanoic acid, which was found only in the free acid form. Analysis of long chain fatty acids at various stages of germination failed to disclose possible precursors of cis-9,10-epoxyoctadecanoic acid or possible metabolic products from the breakdown of threo-9,10-dihydroxyoctadecanoic acid.