Comparative Analyses of Cuticular Waxes on Various Organs of Potato (Solanum tuberosum L.).

Complex mixtures of cuticular waxes coat plant surfaces to seal them against environmental stresses, with compositions greatly varying between species and possibly organs. This paper reports comprehensive analyses of the waxes on both above- and below-ground organs of potato, where total wax coverages varied between petals (2.6 μg/cm), leaves, stems, and tubers (1.8-1.9 μg/cm), and rhizomes (1.1 μg/cm). The wax mixtures on above-ground organs were dominated by alkanes, occurring in homologous series of isomeric C-C n-alkanes, C-C 2-methylalkanes, and C-C 3-methylalkanes. In contrast, below-ground organs had waxes rich in monoacylglycerols (C-C acyls) and C-C alkyl ferulates, together with fatty acids (rhizomes) or primary alcohols (tubers). The organ-specific wax coverages, compound class distribution, and chain length profiles suggest highly regulated activities of wax biosynthesis enzymes, likely related to organ-specific ecophysiological functions.