Water and Solute Permeability of Plant Cuticles: Measurement and ...

1.3 Soluble Cuticular Lipids 9
Fig. 1.3 Scanning electron micrographs of the leaf surface of (a) Quercus robur (oak) and
(b) Vinca major (periwinkle). A delicate pattern of epicuticular wax crystallites is visible on the
oak surface, whereas the periwinkle surface is characterised by a pronounced pattern of cuticular
folding
epi- and intracuticular waxes. Dipping or rinsing leaves with chloroform at room
temperature often results in partial extraction of waxes (Riederer and Schneider
1989) especially when cuticles are thick. By varying solvents and duration of extraction
it has been attempted to selectively extract epicuticular waxes (Silva Fernandes
et al. 1964; Holloway 1974; Baker et al. 1975; Baker and Procopiou 1975). Jetter
et al. (2006) have argued that selective extraction of surface waxes with solvents is
not possible, and they favour various stripping techniques (Ensikat et al. 2000; Jetter
et al. 2000; Riederer and Markstädter 1996). Following stripping, cuticle surfaces
appeared smooth and clean, showing that stripping removes wax bloom completely.
However, there is no direct evidence that smooth continuous wax films covering the
cutin are also removed. These uncertainties affect the validity of conclusions concerning
amounts of surface waxes and effects of surface waxes on permeability of
cuticles. We shall return to this problem in later chapters.