LIPID METABOLISM IN LEAVES OF TUSSILAGO FARFARA DURING INFECTION BY PUCCINIA POARUM

Abstract

SUMMARYFollowing infection by Puccinia poarum, there is an accumulation of lipid in leaf tissue of Tussilago farfara. Most of this increase is in the fungus, which accounts for nearly half of the dry weight of mature aecial pustules. While the lipid content of infected tissue rises to more than three times that of healthy leaves, that of the uninfected parts of diseased leaves is reduced by one‐third. Aerial pustules accumulate a high proportion of neutral lipid, particularly triglycerides and fatty acids. As infection progresses, a loss of chloroplast glycolipids and phosphatidyl glycerol is accompanied by increases in phosphatidyl ethanolamine and phosphatidyl choline and the formation of phosphatidyl serine, which is not readily detectable in healthy leaf tissue. The lipid changes following rust infection have been compared with those of senescing Tussilago leaves.Both neutral lipids and phospholipids incorporated more photosynthetically assimilated C in rust‐infected tissue than in healthy leaves. Greatest differences were in free fatty acids, triglycerides, phosphatidyl ethanolamine and phosphatidyl choline with significant increases also in sterols, phosphatidyl inositol and phosphatidyl serine. Whereas three‐quarters of the activity incorporated from 14CO2 into lipid appears in the neutral lipids of diseased tissue, in healthy tissue these contain only one‐quarter.