Effect of culture conditions on the lipid composition of Phytophthora infestans

Authors


Author for correspondence: John L. Harwood Tel: +44 (0)29 20874108 Fax: +44 (0)29 20874116 Email: harwood@cardiff.ac.uk

Summary

  • • Phytophthora infestans is one of the most important of all plant pathogens and there is a demand for its more effective control. One target area for pesticides is lipid metabolism. To provide background information for studies with pesticides, we examined the lipids of P. infestans and how their composition is altered by culture conditions.
  • • Phytophthora infestans was grown in a pea-broth and three different minimal media. Acyl lipids were extracted, separated by thin-layer chromatography, identified and quantified. Total fatty acid patterns and those in individual lipid classes were measured by gas–liquid chromatography.
  • • Major polar lipids were the phosphoglycerides, phosphatidylcholine > phosphatidylethanolamine > phosphatidylinositol. The proportion of total polar lipids was reduced in minimal media. The similar fatty acid patterns of phosphatidylcholine and phosphatidylethanolamine were consistent with their metabolic relationship. Phytophthora infestans contained significant amounts of 22C unsaturated fatty acids, in addition to common fungal or oomycete fatty acids. Growth on minimal media caused changes in fatty acid patterns with increases in palmitate and linoleate and decreases in oleate being most obvious. Particular changes were also associated with the specific fatty acid patterns of individual lipids.
  • • The changes found in total fatty acids and in the acyl profiles of individual lipids suggest that desaturase activities are altered by growth conditions. These results and the greater proportions of storage triacylglycerol in minimal media agree with data for some other lower plants or fungi.

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