Phenolic constituents of glandular trichomes onSolanum berthaultii andS. polyadenium

Phenolic compounds in Type A glandular trichomes of two insectresistant potato species were separated and identified using a combination of high pressure liquid chromatography (HPLC), UV-visible spectrometry, and¹H proton nuclear magnetic resonance (NMR) procedures. Type A trichomes ofSolanum berthaultii andS. polyadenium contained a phenolic compound tentatively identified as the glucose ester of p-hydroxyphenylpropionic acid. Its presence in trichomes of both species suggests that this compound may play a major role in formation of the brownish, insect entrapping exudate characteristic of trichome-mediated insect resistance in these species. Chlorogenic acid, a major phenolic constituent of Type A trichomes ofSolanum polyadenium was not detected in trichomes of 5.berthaultii. The exclusive presence of chlorogenic acid in trichome exudates ofS. polyadenium may be responsible, at least in part, for the greater levels of insect entrapment by this species, compared with that ofS. berthaultii.