Direct access to plant epicuticular wax crystals by a new mechanical isolation method

A new method for the isolation of wax crystals from plant surfaces is prese nted. The wax-covered plant surface, e.g, a piece of a leaf or fruit, is br ought into contact with a preparation liquid, e.g., glycerol or triethylene glycol, and cooled to ca. -100 degrees C. When the plant specimen is remov ed, the epicuticular wax remains embedded in the frozen liquid. After it wa rms up, the wax layer can be captured on appropriate carriers for further s tudies. This isolation method causes very little stress on the wax crystals ; thus the shape and crystal structure are well preserved. In many cases it is possible, by choosing a preparation liquid with appropriate wettability , to isolate either the entire epicuticular wax layer or only discrete wax crystals without the underlying wax film. These crystals are well suited fo r electron diffraction studies by transmission electron microscopy and high resolution imaging by atomic force microscopy. The absence of intracuticul ar components and other impurities and the feasibility of the selective iso lation of wax crystals enable improved chemical analysis and a more detaile d study of their properties.