Analysis of leaf surface sesquiterpenes in potato varieties.

A comparative study of potato leaf sesquiterpenes was carried out. GC, GC-MS, and NMR analyses were used to identify and quantify the sesquiterpenes in the leaf surfaces of 10 potato (Solanum tuberosum) varieties. Two sesquiterpene alcohols and 17 sesquiterpene hydrocarbons were identified and quantitatively determined. The distribution of the sesquiterpenes was found to be variety-specific. The sesquiterpene contents of the different potato varieties were subjected to cluster and principal component analyses. The eight potato varieties of the main chemotype cluster were dominated by beta-caryophyllene (9-148 ng/cm2), germacrene D (2-46 ng/cm2), germacrene D-4-ol (0.4-31 ng/cm2), beta-sesquiphellandrene (1-34 ng/cm2), and an unknown sesquiterpene alcohol III (0.2-37 ng/cm2). Chemometric classification distinguished two varieties, Mila and Vistula, from a major cluster. The Vistula variety was distinguished from the others by its high contents of beta-caryophyllene, alpha-humulene, germacrene D, and germacrene D-4-ol and the Mila variety by beta-elemene, trans-alpha-bergamotene, (Z)-beta-farnesene, (E)-beta-farnesene, trans-beta-bergamotene, beta-sesquiphellandrene, and unknown sesquiterpene alcohols I, II, III.